Improving temporal resolution of ultrafast electron diffraction by eliminating arrival time jitter induced by radiofrequency bunch compression cavities

The temporal resolution of sub-relativistic ultrafast electron diffraction (UED) is generally limited by radio frequency (RF) phase and amplitude jitter of the RF lenses that are used to compress the electron pulses. We theoretically show how to circumvent this limitation by using a combination of several RF compression cavities. We show that if powered by the same RF source and with a proper choice of RF field strengths, RF phases and distances between the cavities, the combined arrival time jitter due to RF phase jitter of the cavities is cancelled at the compression point. We also show that the effect of RF amplitude jitter on the temporal resolution is negligible when passing through the cavity at a RF phase optimal for (de)compression. This will allow improvement of the temporal resolution in UED experiments to well below 100 fs

Energy spread of ultracold electron bunches extracted from a laser cooled gas

Ultrashort and ultracold electron bunches created by near-threshold femtosecond photoionization of a laser-cooled gas hold great promise for single-shot ultrafast diffraction experiments. In previous publications the transverse beam quality and the bunch length have been determined. Here the longitudinal energy spread of the generated bunches is measured for the first time, using a specially developed Wien filter. The Wien filter has been calibrated by determining the average deflection of the electron bunch as a function of magnetic field. The measured relative energy spread $\frac{\sigma_{U}}{U} = 0.64 \pm 0.09\%$ agrees well with the theoretical model which states that it is governed by the width of the ionization laser and the acceleration length

Theory and particle tracking simulations of a resonant radiofrequency deflection cavity in TM110_{110} mode for ultrafast electron microscopy

We present a theoretical description of resonant radiofrequency (RF) deflecting cavities in TM$_{110}$ mode as dynamic optical elements for ultrafast electron microscopy. We first derive the optical transfer matrix of an ideal pillbox cavity and use a Courant-Snyder formalism to calculate the 6D phase space propagation of a Gaussian electron distribution through the cavity. We derive closed, analytic expressions for the increase in transverse emittance and energy spread of the electron distribution. We demonstrate that for the special case of a beam focused in the center of the cavity, the low emittance and low energy spread of a high quality beam can be maintained, which allows high-repetition rate, ultrafast electron microscopy with 100 fs temporal resolution combined with the atomic resolution of a high-end TEM. This is confirmed by charged particle tracking simulations using a realistic cavity geometry, including fringe fields at the cavity entrance and exit apertures

Assessment of Hydropower Generation and Green Hydrogen Production Potential in Jebba Dam, Nigeria, West Africa

Hydropower can play a significant role in advancing the production of green hydrogen. However, hydro-climatic variability impacts hydropower production and thus the hydrogen potential. In this study, we developed novel analytics to understand how hydropower inter-annual variability translates to hydrogen production. We address this by; (i) analyzing Jebba dam hydro-climatic variables and associated hydropower generation (ii) translating the annual and quarterly hydropower production into hydrogen using five assumed scenarios; (iii) estimating the reelectrification potential and (iv) determining the quantity of petrol (or gasoline) that would be replaced and the amount of CO2 and CO that would be avoided. We find that hydropower energy generation has increased significantly at the station. The estimated annual and quarterly green hydrogen potentials indicated that the highest potentials were 59,111 tons and 18,744 tons and have a re-electrification potential of 1,182 GWh and 374 GWh, which can replace 0.224 million liters and 0.071 million liters of petrol (or gasoline) in the year 2021 and the fourth quarter of 2021–04, respectively. This would prevent 0.52 million kg of CO2, 0.92 thousand kg of CO in the year 2021, and 0.163 million kg of CO2, 0.293 thousand kg of CO emissions in the fourth quarter of 2021–04. The study concludes that the impact of hydro-climatic variation on hydropower generation affects green hydrogen production potential. Nevertheless, using a percentage of hydropower energy can present a unique opportunity to move the nation toward the production of green hydrogen energy as a long-storage solution for rural areas' re-electrification and to meet electricity demand when the hydropower dam’s water storage is low. Furthermore, the adoption of a green hydrogen energy solution can contribute to the nation's and global climate change mitigation efforts

Involving adolescents and young adults (AYA) with an uncertain or poor cancer prognosis as research partners

BackgroundThe interest in patient involvement is increasing in health research, however, is not yet well described in adolescents and young adults (AYA) with palliative cancer, such as AYAs with an uncertain and/or poor cancer prognosis (UPCP). This study aimed to document the process of involving AYAs with a UPCP as partners in research including their experiences, the impact, and our lessons learned.Materials and MethodsAYAs with a UPCP were recruited via healthcare professionals and patients to involve as research partners in the qualitative interview study. To define their role and tasks in each research phase we used the participation matrix.ResultsIn total six AYAs with a UPCP were involved as research partners and five as co-thinkers. They were involved in initiating topics, developing study design, interviewing, analyzing data, and dissemination of information. Together with the researcher, they co-produced the information letters and interview guides and implemented aftercare and extra support. The research partners ensured that the data was relevant, correctly interpreted and that results were translated to peers and clinical practice. AYAs themselves felt useful, found people who understand their challenges, and were able to create a legacy.ConclusionThe benefits of involving AYAs with a UPCP as research partners cannot be stressed enough, both for the study as well as for the AYAs themselves, but there are challenges. Researchers should anticipate and address those challenges during the planning phase of the study. This article provides practical tips on how to do so

All-cause admissions following a first-ever exacerbation-related hospitalization in COPD

Background Hospital admissions are important contributors to the overall burden of chronic obstructive pulmonary disease (COPD). Understanding the patterns and causes of hospital admissions will help to identify targets for preventive interventions. This study aimed to determine the 5-year all-cause hospital admission trajectories of patients with COPD following their first ever exacerbation-related hospitalisation. Methods Patients with COPD were identified from the Danish national registries. Patients experiencing their first ever exacerbation-related hospitalisation, defined as the index event, between 2000 and 2014 were included. All-cause hospital admissions were examined during a subsequent 5-year follow-up period, and categorised using the International Classification of Diseases, 10th revision. Results In total, 82 964 patients with COPD were included. The mean±sd age was 72±10 years and 48% were male. Comorbidities were present in 58%, and 65% of the patients collected inhalation medication ≤6 months prior to the index event. In total, 337 066 all-cause hospital admissions were identified, resulting in a 5-year admission rate of 82%. Most admissions were due to nonrespiratory causes (59%), amongst which cardiac events were most common (19%). Conclusion Hospital admissions following a first exacerbation-related hospitalisation are common; nonrespiratory events constitute the majority of admissions. Besides the respiratory causes, treatment targeting the nonrespiratory causes of hospital admission should be considered to effectively decrease the burden of hospitalisation in COPD

Root developmental programs shape the Medicago truncatula nodule meristem

Nodules on the roots of legume plants host nitrogen-fixing Rhizobium bacteria. Several lines of evidence indicate that nodules are evolutionarily related to roots. We determined whether developmental control of the Medicago truncatula nodule meristem bears resemblance to that in root meristems through analyses of root meristem-expressed PLETHORA genes. In nodules, MtPLETHORA 1 and 2 are preferentially expressed in cells positioned at the periphery of the meristem abutting nodule vascular bundles. Their expression overlaps with an auxin response maximum and MtWOX5, which is a marker for the root quiescent center. Strikingly, the cells in the central part of the nodule meristem have a high level of cytokinin and display MtPLETHORA 3 and 4 gene expression. Nodule-specific knockdown of MtPLETHORA genes results in a reduced number of nodules and/or in nodules in which meristem activity has ceased. Our nodule gene expression map indicates that the nodule meristem is composed of two distinct domains in which different MtPLETHORA gene subsets are expressed. Our mutant studies show that MtPLETHORA genes function redundantly in nodule meristem maintenance. This indicates that Rhizobium has recruited root developmental programs for nodule formation

Der Einfluss der Kapazitätsgröße und -auslastung auf den Kostenverlauf ausgewählter Hilfskostenstellen von Molkereien - Abteilung Dampfversorgung

Die Kostenanalyse zur Bestimmung des Einflusses der Kapazitätsgröße und -auslastung auf den Kostenverlauf von Hilfskostenstellen (Hilfsabteilungen) erfolgt mit Hilfe von Modellkalkulationen. Eine spezielle Form der Teilkostenrechnung ermöglicht die Zurechnung der Kosten nach Kostenkategorien (jahresfix, tagesfix, ggf. chargenfix und mengenproportional) auf die entsprechenden Kostenträger (z. B. Kälte, Dampf) der jeweiligen Hilfskostenstelle. Durch computergestützte Simulationen können die Auswirkungen der verschiedenen Kosteneinflußfaktoren im einzelnen quantifiziert werden