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2. KineCluE: a Kinetic Cluster Expansion code to compute transport coefficients beyond the dilute limit

Author

Schuler, T., Messina, L., and Nastar, M

Subjects
Condensed Matter - Statistical Mechanics, Condensed Matter - Materials Science
Abstract

This paper introduces the KineCluE code that implements the self-consistent mean-field theory for clusters of finite size. Transport coefficients are obtained as a sum over cluster contributions (in a cluster expansion formalism), each being individually computed with KineCluE. This method allows for the calculation of these coefficients beyond the infinitely dilute limit, and is an important step in bridging the gap between dilute and concentrated approaches. Inside a finite volume of space containing the components of a given cluster, all kinetic trajectories are accounted for in an exact manner. The code, written in Python, adapts to a wide variety of systems, with various crystallographic structures (possibly under strain), defects and solute amount and types, and various jump mechanisms, including collective ones. The code also features a set of useful tools, such as the sensitivity study routine that allows for the identification of the most important jump frequencies to get accurate transport coefficients with minimum computational cost., Comment: Code is available upon request

Published
2018
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3. Fuel-cell catalyst-layer resistance via hydrogen limiting-current measurements

Author

Schuler, T, Chowdhury, A, Freiberg, AT, Sneed, B, Spingler, FB, Tucker, MC, More, KL, Radke, CJ, and Weber, AZ

Subjects
Energy, Macromolecular and Materials Chemistry, Physical Chemistry (incl. Structural), Materials Engineering
Abstract

Significant mass-transport resistances in polymer-electrolyte-fuel-cell catalyst layers (CLs) impose a lower limit on Pt-loading levels, hindering wide-spread fuel-cell commercialization. The origin of this resistance remains unclear. Minimization of CL mass-transport resistance is imperative to achieve better CL design and performance. In this paper, an operando method based on H2 limiting current is used to characterize and quantify CL resistance in traditional porous Pt/carbon-based electrodes. CL sub-resistances are isolated using continuum multiscale modeling and experiments, investigating the effects of reactant molecular weight, pressure, and ionomer to carbon weight ratio. The results expose CL resistance including both interfacial and transport components, although the majority of the CL resistance is ascribed to a local resistance close to the Pt reaction sites, which includes interfacial resistance and local transport resistance. Variations in temperature, humidity, and primary particle loading (Pt:C ratio) highlight the impact of operating conditions and CL design parameters on CL sub-resistances. The observed trends guide optimization of CL design to achieve novel low-loaded fuel-cell electrodes.

Published
2019

4. Investigating fuel-cell transport limitations using hydrogen limiting current

Author

Spingler, FB, Phillips, A, Schuler, T, Tucker, MC, and Weber, AZ

Subjects
Limiting current, Resistance, Catalyst layer, Effective diffusivity, Gas-diffusion layer, Low loading, Energy, Engineering, Chemical Sciences
Abstract

Reducing mass-transport losses in polymer-electrolyte fuel cells (PEFCs) is essential to increase their power density and reduce overall stack cost. At the same time, cost also motivates the reduction in expensive precious-metal catalysts, which results in higher local transport losses in the catalyst layers. In this paper, we use a hydrogen-pump limiting-current setup to explore the gas-phase transport losses through PEFC catalyst layers and various gas-diffusion and microporous layers. It is shown that the effective diffusivity in the gas-diffusion layers is a strong function of liquid saturation. In addition, it is shown how the catalyst layer unexpectedly contributes significantly to the overall measured transport resistance. This is especially true for low catalyst loadings. It is also shown how the various losses can be separated into different mechanisms including diffusional processes and mass-dependent and independent ones, where the data suggests that a large part of the transport resistance in catalyst layers cannot be attributed to a gas-phase diffusional process. The technique is promising for deconvoluting transport losses in PEFCs.

Published
2017

5. Towards the modeling of the interplay between radiation induced segregation and sink microstructure.

Author

Schuler, T., Nastar, M., and Soisson, F.

Subjects
*AB-initio calculations, *CRYSTAL grain boundaries, *MICROSTRUCTURE, *RADIATION
Abstract

Excess point defects created by irradiation in metallic alloys diffuse and annihilate at sinks available in the microstructure, such as grain boundaries, dislocations, or point defect clusters. Fluxes of defects create fluxes of alloying elements, leading to local changes of composition near the sinks and to a modification of the properties of the materials. The direction and the amplitude of this radiation-induced segregation, its tendency to produce an enrichment or a depletion of solute, depend on a set of transport coefficients that are very difficult to measure experimentally. The understanding of radiation-induced segregation phenomena has, however, made significant progress in recent years, thanks to the modeling at different scales of diffusion and segregation mechanisms. We review here these different advances and try to identify the key scientific issues that limit the development of predictive models, applicable to real alloys. The review addresses three main issues: the calculation of the transport coefficients from ab initio calculations, the modeling of segregation kinetics at static point defects sinks—mainly by kinetic Monte Carlo or diffusion-reaction models—and the more challenging task of modeling the dynamic interplay between radiation-induced segregation and sink microstructure evolution, especially when this evolution results from annihilation of point defects. From this overview of the current state-of-the-art in this field, we discuss still-open questions and guidelines for what constitutes, in our opinion, the desirable future works on this topic. [ABSTRACT FROM AUTHOR]

Published
2022
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9. Interfacial engineering via laser ablation for high-performing PEM water electrolysis

Author

Lee, JK, Lee, JK, Schuler, T, Bender, G, Sabharwal, M, Peng, X, Weber, AZ, Danilovic, N, Lee, JK, Lee, JK, Schuler, T, Bender, G, Sabharwal, M, Peng, X, Weber, AZ, and Danilovic, N

Abstract

A rationalized interfacial design strategy was applied to tailor the porous transport layer (PTL)-catalyst layer (CL) contact and the PTL bulk-phase architecture. Particularly, at the PTL-CL interface, our results reveal that laser ablated sintered titanium power-based PTLs improve electrolyzer performance at both the H2NEW Consortium baseline catalyst loading of 0.4 mgIr·cm−2 as well as at the ultra-low catalyst loading of 0.055 mgIr·cm−2. Under ultra-low catalyst loadings, the laser ablated PTL demonstrates maximum reduction of 230 mV compared to the commercial PTL at 4 A·cm−2, and reduces by 68 mV at 3.2 A·cm−2 under H2NEW baseline loading. Laser ablation alters the titanium phase at the interface, so it forms more uniform structure like a microporous layer or a backing layer, leading to an increase in the surface area in contact with the catalyst layer while preventing the membrane from deforming into the PTL. Moreover, we reveal that bulk-phase architecture modification of the PTL by ablating patterned pores at the flow field-PTL interface improves mass transport without sacrificing contact at the CL-PTL interface. Overall, laser ablation of the PTL is an effective method to customize interfacial design to enhance proton exchange membrane electrolyzer performance.

Published
2023

10. Wearable-Triggered Ecological Momentary Assessments Are Feasible in People With Advanced Cancer and Their Family Caregivers: Feasibility Study from an Outpatient Palliative Care Clinic at a Cancer Center.

Author

Schuler, T, King, C, Matsveru, T, Back, M, Clark, K, Chin, D, Lilian, R, Gallego, B, Coiera, E, Currow, DC, Schuler, T, King, C, Matsveru, T, Back, M, Clark, K, Chin, D, Lilian, R, Gallego, B, Coiera, E, and Currow, DC

Abstract

Background: Emerging digital health approaches could play a role in better personalized palliative care. Aim: We conducted a feasibility study testing wearable sensor (WS)-triggered ecological momentary assessments (EMAs) and electronic patient-reported outcomes in community palliative care with patient-caregiver dyads. Design: All wore consumer-grade WS for five weeks. Sensor-detected "stress" (heart rate variability algorithm) that passed individualized thresholds triggered a short smartphone survey. Daily sleep surveys, weekly symptom surveys (Integrated Palliative care Outcome Scale), and a poststudy experience survey were conducted. Setting/Participants: Fifteen dyads (n = 30) were recruited from an outpatient palliative care clinic for people with cancer. Results: Daytime sensor wear-time had 73% adherence. Participants perceived value in this support. Quantity and severity of "stress" events were higher in patients. Sleep disturbance was similar but for different reasons: patients (physical symptoms) and caregivers (worrying about the patient). Conclusions: EMAs are feasible and valued in community palliative care.

Published
2023

12. Glacier observational data assimilation for mass balance modelling in Svalbard

Author

Cao, W., Schmidt, L., Aalstad, K., Westermann, S., and Schuler, T.

Abstract

Accurate estimation of glacier mass balance is vital in several fields, including climate change impact assessment and water resource management. However, classical modelling approaches on a regional scale are usually hampered by uncertainties in forcing data, model structure, and parameter values. Data assimilation is a method to incorporate observations into modellings and to effectively reduce the uncertainty of results. So far, it has been rarely used in glacier mass balance modelling. Here, we test different assimilation methods, including ensemble Kalman filters and smoothers, to incorporate albedo derived from MODIS data and stake readings from in-situ mass-balance measurements into an energy balance model applied to Svalbard glaciers. The overall objective is to improve the accuracy of glacier mass balance reconstruction and forecasting in Svalbard by combining observations and models. In a range of experiments, we analyze the performance of different assimilation methods and different observation products. One of the research challenges is to identify the information content of different observations and determine at which level they influence the model behaviour. We compare the prior and posterior states to help disentangle which process or forcing has the most impact on the uncertainty of the model’s results. &nbsp, The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023
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15. Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

Author

Cossarizza, A, Chang, H, Radbruch, A, Abrignani, S, Addo, R, Akdis, M, Andra, I, Andreata, F, Annunziato, F, Arranz, E, Bacher, P, Bari, S, Barnaba, V, Barros-Martins, J, Baumjohann, D, Beccaria, C, Bernardo, D, Boardman, D, Borger, J, Bottcher, C, Brockmann, L, Burns, M, Busch, D, Cameron, G, Cammarata, I, Cassotta, A, Chang, Y, Chirdo, F, Christakou, E, Cicin-Sain, L, Cook, L, Corbett, A, Cornelis, R, Cosmi, L, Davey, M, De Biasi, S, De Simone, G, del Zotto, G, Delacher, M, Di Rosa, F, Santo, J, Diefenbach, A, Dong, J, Dorner, T, Dress, R, Dutertre, C, Eckle, S, Eede, P, Evrard, M, Falk, C, Feuerer, M, Fillatreau, S, Fiz-Lopez, A, Follo, M, Foulds, G, Frobel, J, Gagliani, N, Galletti, G, Gangaev, A, Garbi, N, Garrote, J, Geginat, J, Gherardin, N, Gibellini, L, Ginhoux, F, Godfrey, D, Gruarin, P, Haftmann, C, Hansmann, L, Harpur, C, Hayday, A, Heine, G, Hernandez, D, Herrmann, M, Hoelsken, O, Huang, Q, Huber, S, Huber, J, Huehn, J, Hundemer, M, Hwang, W, Iannacone, M, Ivison, S, Jack, H, Jani, P, Keller, B, Kessler, N, Ketelaars, S, Knop, L, Knopf, J, Koay, H, Kobow, K, Kriegsmann, K, Kristyanto, H, Krueger, A, Kuehne, J, Kunze-Schumacher, H, Kvistborg, P, Kwok, I, Latorre, D, Lenz, D, Levings, M, Lino, A, Liotta, F, Long, H, Lugli, E, Macdonald, K, Maggi, L, Maini, M, Mair, F, Manta, C, Manz, R, Mashreghi, M, Mazzoni, A, Mccluskey, J, Mei, H, Melchers, F, Melzer, S, Mielenz, D, Monin, L, Moretta, L, Multhoff, G, Munoz, L, Munoz-Ruiz, M, Muscate, F, Natalini, A, Neumann, K, Ng, L, Niedobitek, A, Niemz, J, Almeida, L, Notarbartolo, S, Ostendorf, L, Pallett, L, Patel, A, Percin, G, Peruzzi, G, Pinti, M, Pockley, A, Pracht, K, Prinz, I, Pujol-Autonell, I, Pulvirenti, N, Quatrini, L, Quinn, K, Radbruch, H, Rhys, H, Rodrigo, M, Romagnani, C, Saggau, C, Sakaguchi, S, Sallusto, F, Sanderink, L, Sandrock, I, Schauer, C, Scheffold, A, Scherer, H, Schiemann, M, Schildberg, F, Schober, K, Schoen, J, Schuh, W, Schuler, T, Schulz, A, Schulz, S, Schulze, J, Simonetti, S, Singh, J, Sitnik, K, Stark, R, Starossom, S, Stehle, C, Szelinski, F, Tan, L, Tarnok, A, Tornack, J, Tree, T, van Beek, J, van de Veen, W, van Gisbergen, K, Vasco, C, Verheyden, N, von Borstel, A, Ward-Hartstonge, K, Warnatz, K, Waskow, C, Wiedemann, A, Wilharm, A, Wing, J, Wirz, O, Wittner, J, Yang, J, Cossarizza A., Chang H. -D., Radbruch A., Abrignani S., Addo R., Akdis M., Andra I., Andreata F., Annunziato F., Arranz E., Bacher P., Bari S., Barnaba V., Barros-Martins J., Baumjohann D., Beccaria C. G., Bernardo D., Boardman D. A., Borger J., Bottcher C., Brockmann L., Burns M., Busch D. H., Cameron G., Cammarata I., Cassotta A., Chang Y., Chirdo F. G., Christakou E., Cicin-Sain L., Cook L., Corbett A. J., Cornelis R., Cosmi L., Davey M. S., De Biasi S., De Simone G., del Zotto G., Delacher M., Di Rosa F., Santo J. D., Diefenbach A., Dong J., Dorner T., Dress R. J., Dutertre C. -A., Eckle S. B. G., Eede P., Evrard M., Falk C. S., Feuerer M., Fillatreau S., Fiz-Lopez A., Follo M., Foulds G. A., Frobel J., Gagliani N., Galletti G., Gangaev A., Garbi N., Garrote J. A., Geginat J., Gherardin N. A., Gibellini L., Ginhoux F., Godfrey D. I., Gruarin P., Haftmann C., Hansmann L., Harpur C. M., Hayday A. C., Heine G., Hernandez D. C., Herrmann M., Hoelsken O., Huang Q., Huber S., Huber J. E., Huehn J., Hundemer M., Hwang W. Y. K., Iannacone M., Ivison S. M., Jack H. -M., Jani P. K., Keller B., Kessler N., Ketelaars S., Knop L., Knopf J., Koay H. -F., Kobow K., Kriegsmann K., Kristyanto H., Krueger A., Kuehne J. F., Kunze-Schumacher H., Kvistborg P., Kwok I., Latorre D., Lenz D., Levings M. K., Lino A. C., Liotta F., Long H. M., Lugli E., MacDonald K. N., Maggi L., Maini M. K., Mair F., Manta C., Manz R. A., Mashreghi M. -F., Mazzoni A., McCluskey J., Mei H. E., Melchers F., Melzer S., Mielenz D., Monin L., Moretta L., Multhoff G., Munoz L. E., Munoz-Ruiz M., Muscate F., Natalini A., Neumann K., Ng L. G., Niedobitek A., Niemz J., Almeida L. N., Notarbartolo S., Ostendorf L., Pallett L. J., Patel A. A., Percin G. I., Peruzzi G., Pinti M., Pockley A. G., Pracht K., Prinz I., Pujol-Autonell I., Pulvirenti N., Quatrini L., Quinn K. M., Radbruch H., Rhys H., Rodrigo M. B., Romagnani C., Saggau C., Sakaguchi S., Sallusto F., Sanderink L., Sandrock I., Schauer C., Scheffold A., Scherer H. U., Schiemann M., Schildberg F. A., Schober K., Schoen J., Schuh W., Schuler T., Schulz A. R., Schulz S., Schulze J., Simonetti S., Singh J., Sitnik K. M., Stark R., Starossom S., Stehle C., Szelinski F., Tan L., Tarnok A., Tornack J., Tree T. I. M., van Beek J. J. P., van de Veen W., van Gisbergen K., Vasco C., Verheyden N. A., von Borstel A., Ward-Hartstonge K. A., Warnatz K., Waskow C., Wiedemann A., Wilharm A., Wing J., Wirz O., Wittner J., Yang J. H. M., Yang J., Cossarizza, A, Chang, H, Radbruch, A, Abrignani, S, Addo, R, Akdis, M, Andra, I, Andreata, F, Annunziato, F, Arranz, E, Bacher, P, Bari, S, Barnaba, V, Barros-Martins, J, Baumjohann, D, Beccaria, C, Bernardo, D, Boardman, D, Borger, J, Bottcher, C, Brockmann, L, Burns, M, Busch, D, Cameron, G, Cammarata, I, Cassotta, A, Chang, Y, Chirdo, F, Christakou, E, Cicin-Sain, L, Cook, L, Corbett, A, Cornelis, R, Cosmi, L, Davey, M, De Biasi, S, De Simone, G, del Zotto, G, Delacher, M, Di Rosa, F, Santo, J, Diefenbach, A, Dong, J, Dorner, T, Dress, R, Dutertre, C, Eckle, S, Eede, P, Evrard, M, Falk, C, Feuerer, M, Fillatreau, S, Fiz-Lopez, A, Follo, M, Foulds, G, Frobel, J, Gagliani, N, Galletti, G, Gangaev, A, Garbi, N, Garrote, J, Geginat, J, Gherardin, N, Gibellini, L, Ginhoux, F, Godfrey, D, Gruarin, P, Haftmann, C, Hansmann, L, Harpur, C, Hayday, A, Heine, G, Hernandez, D, Herrmann, M, Hoelsken, O, Huang, Q, Huber, S, Huber, J, Huehn, J, Hundemer, M, Hwang, W, Iannacone, M, Ivison, S, Jack, H, Jani, P, Keller, B, Kessler, N, Ketelaars, S, Knop, L, Knopf, J, Koay, H, Kobow, K, Kriegsmann, K, Kristyanto, H, Krueger, A, Kuehne, J, Kunze-Schumacher, H, Kvistborg, P, Kwok, I, Latorre, D, Lenz, D, Levings, M, Lino, A, Liotta, F, Long, H, Lugli, E, Macdonald, K, Maggi, L, Maini, M, Mair, F, Manta, C, Manz, R, Mashreghi, M, Mazzoni, A, Mccluskey, J, Mei, H, Melchers, F, Melzer, S, Mielenz, D, Monin, L, Moretta, L, Multhoff, G, Munoz, L, Munoz-Ruiz, M, Muscate, F, Natalini, A, Neumann, K, Ng, L, Niedobitek, A, Niemz, J, Almeida, L, Notarbartolo, S, Ostendorf, L, Pallett, L, Patel, A, Percin, G, Peruzzi, G, Pinti, M, Pockley, A, Pracht, K, Prinz, I, Pujol-Autonell, I, Pulvirenti, N, Quatrini, L, Quinn, K, Radbruch, H, Rhys, H, Rodrigo, M, Romagnani, C, Saggau, C, Sakaguchi, S, Sallusto, F, Sanderink, L, Sandrock, I, Schauer, C, Scheffold, A, Scherer, H, Schiemann, M, Schildberg, F, Schober, K, Schoen, J, Schuh, W, Schuler, T, Schulz, A, Schulz, S, Schulze, J, Simonetti, S, Singh, J, Sitnik, K, Stark, R, Starossom, S, Stehle, C, Szelinski, F, Tan, L, Tarnok, A, Tornack, J, Tree, T, van Beek, J, van de Veen, W, van Gisbergen, K, Vasco, C, Verheyden, N, von Borstel, A, Ward-Hartstonge, K, Warnatz, K, Waskow, C, Wiedemann, A, Wilharm, A, Wing, J, Wirz, O, Wittner, J, Yang, J, Cossarizza A., Chang H. -D., Radbruch A., Abrignani S., Addo R., Akdis M., Andra I., Andreata F., Annunziato F., Arranz E., Bacher P., Bari S., Barnaba V., Barros-Martins J., Baumjohann D., Beccaria C. G., Bernardo D., Boardman D. A., Borger J., Bottcher C., Brockmann L., Burns M., Busch D. H., Cameron G., Cammarata I., Cassotta A., Chang Y., Chirdo F. G., Christakou E., Cicin-Sain L., Cook L., Corbett A. J., Cornelis R., Cosmi L., Davey M. S., De Biasi S., De Simone G., del Zotto G., Delacher M., Di Rosa F., Santo J. D., Diefenbach A., Dong J., Dorner T., Dress R. J., Dutertre C. -A., Eckle S. B. G., Eede P., Evrard M., Falk C. S., Feuerer M., Fillatreau S., Fiz-Lopez A., Follo M., Foulds G. A., Frobel J., Gagliani N., Galletti G., Gangaev A., Garbi N., Garrote J. A., Geginat J., Gherardin N. A., Gibellini L., Ginhoux F., Godfrey D. I., Gruarin P., Haftmann C., Hansmann L., Harpur C. M., Hayday A. C., Heine G., Hernandez D. C., Herrmann M., Hoelsken O., Huang Q., Huber S., Huber J. E., Huehn J., Hundemer M., Hwang W. Y. K., Iannacone M., Ivison S. M., Jack H. -M., Jani P. K., Keller B., Kessler N., Ketelaars S., Knop L., Knopf J., Koay H. -F., Kobow K., Kriegsmann K., Kristyanto H., Krueger A., Kuehne J. F., Kunze-Schumacher H., Kvistborg P., Kwok I., Latorre D., Lenz D., Levings M. K., Lino A. C., Liotta F., Long H. M., Lugli E., MacDonald K. N., Maggi L., Maini M. K., Mair F., Manta C., Manz R. A., Mashreghi M. -F., Mazzoni A., McCluskey J., Mei H. E., Melchers F., Melzer S., Mielenz D., Monin L., Moretta L., Multhoff G., Munoz L. E., Munoz-Ruiz M., Muscate F., Natalini A., Neumann K., Ng L. G., Niedobitek A., Niemz J., Almeida L. N., Notarbartolo S., Ostendorf L., Pallett L. J., Patel A. A., Percin G. I., Peruzzi G., Pinti M., Pockley A. G., Pracht K., Prinz I., Pujol-Autonell I., Pulvirenti N., Quatrini L., Quinn K. M., Radbruch H., Rhys H., Rodrigo M. B., Romagnani C., Saggau C., Sakaguchi S., Sallusto F., Sanderink L., Sandrock I., Schauer C., Scheffold A., Scherer H. U., Schiemann M., Schildberg F. A., Schober K., Schoen J., Schuh W., Schuler T., Schulz A. R., Schulz S., Schulze J., Simonetti S., Singh J., Sitnik K. M., Stark R., Starossom S., Stehle C., Szelinski F., Tan L., Tarnok A., Tornack J., Tree T. I. M., van Beek J. J. P., van de Veen W., van Gisbergen K., Vasco C., Verheyden N. A., von Borstel A., Ward-Hartstonge K. A., Warnatz K., Waskow C., Wiedemann A., Wilharm A., Wing J., Wirz O., Wittner J., Yang J. H. M., and Yang J.

Abstract

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

Published
2021

22. Simulating snow redistribution and its effect on ground surface temperature at a high‐Arctic site on Svalbard

Author

Zweigel, R. B., Westermann, S., Nitzbon, J., Langer, Moritz, Boike, J., Etzelmüller, B., Schuler, T. V., Zweigel, R. B., Westermann, S., Nitzbon, J., Langer, Moritz, Boike, J., Etzelmüller, B., and Schuler, T. V.

Abstract

In high‐latitude and mountain regions, local processes such as redistribution by wind, snow metamorphism and percolation of water, produce a complex spatial distribution of snow depths and snow densities. With its strong control on the ground thermal regime, this snow distribution has pronounced effects on ground temperatures at small spatial scales which are typically not resolved by land surface models (LSMs). This limits our ability to simulate the local impacts of climate change on for example vegetation and permafrost. Here, we present a tiling approach combining the CryoGrid permafrost model with snow microphysics parametrizations from the CROCUS snow scheme to account for sub‐grid lateral exchange of snow and water in a process‐based way. We demonstrate that a simple setup with three coupled tiles, each representing a different snow accumulation class with a specific topographic setting, can reproduce the observed spread of winter‐time ground surface temperatures (GST) and end‐of‐season snow distribution for a high‐Arctic site on Svalbard. For the three‐year study period, the three‐tile simulations showed substantial improvement compared to traditional single‐tile simulations which naturally cannot account for sub‐grid variability. Amongst others, the representation of the warmest and coldest 5% of the observed GST distribution was improved by 1‐2°C, while still capturing the average of the distribution. The simulations also reveal positive mean annual GSTs at the locations receiving the greatest snow cover. This could be an indication for the onset of localized permafrost degradation which would be obscured in single‐tile simulations.

Published
2021

24. The Substructure of the Solar Corona Observed in the Hi-C Telescope

Author

Winebarger, A, Cirtain, J, Golub, L, DeLuca, E, Savage, S, Alexander, C, and Schuler, T

Subjects
Astronomy
Abstract

In the summer of 2012, the High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore calculate how the intensity scales from a low-resolution (AIA) pixels to high-resolution (Hi-C) pixels for both the dynamic events and "background" emission (meaning, the steady emission over the 5 minutes of data acquisition time). We find there is no evidence of substructure in the background corona; the intensity scales smoothly from low-resolution to high-resolution Hi-C pixels. In transient events, however, the intensity observed with Hi-C is, on average, 2.6 times larger than observed with AIA. This increase in intensity suggests that AIA is not resolving these events. This result suggests a finely structured dynamic corona embedded in a smoothly varying background.

Published
2014

25. Discovery of Finely Structured Dynamic Solar Corona Observed in the Hi-C Telescope

Author

Winebarger, A, Cirtain, J, Golub, L, DeLuca, E, Savage, S, Alexander, C, and Schuler, T

Subjects
Solar Physics
Abstract

In the summer of 2012, the High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore examine how the intensity scales from AIA resolution to Hi-C resolution. For each low-resolution pixel, we calculate the standard deviation in the contributing high-resolution pixel intensities and compare that to the expected standard deviation calculated from the noise. If these numbers are approximately equal, the corona can be assumed to be smoothly varying, i.e. have no evidence of substructure in the Hi-C image to within Hi-C's ability to measure it given its throughput and readout noise. A standard deviation much larger than the noise value indicates the presence of substructure. We calculate these values for each low-resolution pixel for each frame of the Hi-C data. On average, 70 percent of the pixels in each Hi-C image show no evidence of substructure. The locations where substructure is prevalent is in the moss regions and in regions of sheared magnetic field. We also find that the level of substructure varies significantly over the roughly 160 s of the Hi-C data analyzed here. This result indicates that the finely structured corona is concentrated in regions of heating and is highly time dependent.

Published
2014

26. A LTS-SQUID system for archaeological prospection and its practical test in Peru

Author

Linzen, S., Chwala, A., Schultze, V., Schulz, M., Schuler, T., Stolz, R., Bondarenko, N., and Meyer, H.-G.

Subjects
Geomagnetism -- Measurement, Geographic information systems -- Usage, Soil research -- Technology application, Geographic information system, Technology application, Business, Electronics, Electronics and electrical industries
Abstract

A new geomagnetic field measurement system for the detection of archaeological signatures in soils which provides a unique fast mapping of large area with high magnetic field gradient resolution as well as lateral precision is presented.

Published
2007

27. Mesoscopic analyses of the impact of morphology and operating conditions on the transport resistances in a proton-exchange-membrane fuel-cell catalyst layer

Author

Mu, YT, Mu, YT, Weber, AZ, Gu, ZL, Schuler, T, Tao, WQ, Mu, YT, Mu, YT, Weber, AZ, Gu, ZL, Schuler, T, and Tao, WQ

Abstract

Exploring the origins of local transport resistance and characterizing the oxygen transport resistances in the catalyst layer (RCL) are critical for cost reduction. In this paper, a comprehensive mesoscopic model for simulating coupled transport processes of oxygen and water vapor for different structural parameters under different operating conditions in reconstructed microstructures is proposed. The local transport resistance is calculated after achieving the limiting current density and the effective diffusivity of oxygen. The results demonstrate that RCL increases greatly with decreasing platinum loading (LPt) and the transport resistances in other components of the cell dominate for high-loadings. Both the reduced oxygen permeation coefficient in the ionomer thin-film and the adsorption resistance account for the origins of local transport resistance. The local transport resistance increases with the bare carbon ratio for a constant LPt and Pt/C ratio due to the decreased effective ionomer surface, and increases with the I/C ratio due to the increased ionomer thickness and decreased Knudsen diffusivity. Due to the presence of liquid water, a slight decrease followed by an increase of the local transport resistance versus relative humidity is obtained. The contribution of ionomer thin-films to RCL is more sensitive to liquid saturation compared with that of pores. This journal is

Published
2020

29. Archaeometric prospection with high-T[subscript c] gradiometers

Author

Chwala, A., IJsselsteijn, R., May, T., Oukhanski, N., Schuler, T., Schultze, V., Stolz, R., and Meyer, H.G.

Subjects
Magnetometer -- Research, Superconductive devices -- Research, Magnetic fields -- Research, Geomagnetism -- Research, Archaeology -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Use of SQUIDs for archaeological prospection is discussed.

Published
2003

32. HTS dc SQUID systems for geophysical prospection

Author

Zakosarenko, V., Chwala, A., Ramos, J., Stolz, R., Schultze, V., Lutjen, H., Blume, J., Schuler, T., and Meyer, H.G.

Subjects
Geophysical instruments -- Design and construction, Superconducting quantum interference devices -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

A high Tc flip-chip dc SQUID magnetometer was used in systems for geophysical prospection methods, such as the Transient Electro Magnetics method.

Published
2001

36. Biodiversity and non-target impacts: a case study of Bt maize in Kenya.

Author

Birch, A. N. E., primary, Wheatley, R., additional, Anyango, B., additional, Arpaia, S., additional, Capalbo, D., additional, Getu Degaga, E., additional, Fontes, E., additional, Kalama, P., additional, Lelmen, E., additional, Løvei, G., additional, Melo, I. S., additional, Muyekho, F., additional, Ngi-Song, A., additional, Ochieno, D., additional, Ogwang, J., additional, Pitelli, R., additional, Schuler, T., additional, Sétamou, M., additional, Sithanantham, S., additional, Smith, J., additional, Son, N. van, additional, Songa, J., additional, Sujii, E., additional, Tan, T. Q., additional, Wan, F. H., additional, and Hilbeck, A., additional

Published
2004
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38. Planetary Exploration Using CubeSat Deployed Sailplanes

Author

Bouskela, A., Kling, A., Chandra, A., Schuler, T., Shkarayev, S., and Jekan Thangavelautham

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), FOS: Physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Earth and Planetary Astrophysics
Abstract

Exploration of terrestrial planets such as Mars are conducted using orbiters, landers and rovers. Cameras and instruments onboard orbiters have enabled global mapping of Mars at low spatial resolution. Landers and rovers such as the Mars Science Laboratory (MSL) carry state-of-the-art instruments to characterize small localized areas. This leaves a critical gap in exploration capabilities: mapping regions in the hundreds of kilometers range. In this paper, we extend our work on CubeSat-sized sailplanes with detailed design studies of different aircraft configurations and payloads, identifying generalized design principles for autonomous sailplane-based surface reconnaissance and science applications. We further analyze potential wing deployment technologies, including conventional inflatables with hardened membranes, use of composite inflatables, and quick-setting foam. We perform detailed modeling of the Martian atmosphere and possible flight patterns at Jerezo crater using the Mars Regional Atmospheric Modeling System (MRAMS) to provide realistic atmospheric conditions at the landing site for NASA's 2020 rover. We revisit the feasibility of the Mars Sailplane concept, comparing it to previously proposed solutions, and identifying pathways to build laboratory prototypes for high-altitude Earth based testing. Finally, our work will analyze the implications of this technology for exploring other planetary bodies with atmospheres, including Venus and Titan., Comment: 14 pages, 18 figures, International Astronautical Congress 2019

Published
2019
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42. Sexual Transmission and Propagation of SIV and HIV in Resting and Activated CD4+ T Cells

Author

Zhang, Z.-Q., Schuler, T., Zupancic, M., Wietgrefe, S., Staskus, K. A., Reimann, K. A., Reinhart, T. A., Rogan, M., Cavert, W., Miller, C. J., Veazey, R. S., Notermans, D., Little, S., Danner, S. A., Richman, D. D., Havlir, D., Wong, J., Jordan, H. L., Schacker, T. W., Racz, P., Tenner-Racz, K., Letvin, N. L., Wolinsky, S., and Haase, A. T.

Published
1999

45. Erratum: “Image-plate sensitivity to x rays at 2 to 60 keV” [Rev. Sci. Instrum. 90, 013506 (2019)]

Author

Rosenberg, M. J., primary, Thorn, D. B., additional, Izumi, N., additional, Williams, D., additional, Rowland, M., additional, Torres, G., additional, Haugh, M., additional, Hillyard, P., additional, Adelman, N., additional, Schuler, T., additional, Barrios, M. A., additional, Holder, J. P., additional, Schneider, M. B., additional, Fournier, K. B., additional, Bradley, D. K., additional, and Regan, S. P., additional

Published
2019
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46. Image-plate sensitivity to x rays at 2 to 60 keV

Author

Rosenberg, M. J., primary, Thorn, D. B., additional, Izumi, N., additional, Williams, D., additional, Rowland, M., additional, Torres, G., additional, Haugh, M., additional, Hillyard, P., additional, Adelman, N., additional, Schuler, T., additional, Barrios, M. A., additional, Holder, J. P., additional, Schneider, M. B., additional, Fournier, K. B., additional, Bradley, D. K., additional, and Regan, S. P., additional

Published
2019
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47. ifo Konjunkturprognose 2017/2018: Deutsche Wirtschaft stark und stabil

Author

Wollmershäuser, T., Nierhaus, W., Hristov, N., Boumans, D., Göttert, M., Grimme, C., Lauterbacher, S., Lehmann, R., Meister, W., Peichl, A., R., Magnus, Schröter, F., Schuler, T., Stöckli, M., Wohlrabe, K., Wolf, A., and Zeiner, C.

Subjects
O10, Konjunktur, Internationale Konjunktur, Welt, ddc:330, F01, Internationale Wirtschaft, Eurozone, Deutschland, Wirtschaftsprognose
Abstract

Der Aufschwung, in dem sich die deutsche Wirtschaft seit nunmehr 2013 befindet, gewinnt an Stärke und Breite. Das ifo Institut rechnet mit einem Zuwachs des realen Bruttoinlandsprodukts von 1,8% im laufenden und 2,0% im kommenden Jahr. Wie schon in den vergangenen Jahren wird die konjunkturelle Entwicklung von der weiter lebhaften Konsumnachfrage der privaten Haushalte und der regen Bautätigkeit bestimmt. Einen zunehmenden Beitrag zum Aufschwung werden die Exporte leisten.

Published
2017

50. Model study of soft x-ray spectroscopy techniques for observing magnetic circular dichroism in buried SmCo magnetic films.

Author

Itza-Ortiz, S., Ederer, D. L., Schuler, T. M., Ruzycki, N., Jiang, J. Samuel, and Bader, S. D.

Subjects
DICHROISM, X-ray spectroscopy, MAGNETIC films
Abstract

X-ray emission and absorption spectroscopy (XES and XAS, respectively) are important and powerful techniques for determining the electronic properties of materials. Both are used to study magnetic circular dichroism (MCD) which is especially useful for analyzing the magnetic properties of materials. We present XAS and XES measurements and a MCD model study of two thin film layered samples containing SmCo layers in order to report on the applicability of soft x-ray spectroscopic techniques to determine the composition, layer thickness, and electronic structure of such materials. Using a transmission by fluorescence attenuation (TFA) technique we determined the composition and thickness of the SmCo layer to be consistent with the intended composition and thickness. We also confirmed the thickness of the other layers by comparing the XES from the thin film with that of a bulk sample. We showed by a model study that TFA could be used to obtain MCD, and thus the anisotropy of the sample, for film thicknesses between about 400 and 800 Å. [ABSTRACT FROM AUTHOR]

Published
2003
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