Adatom diffusion in high electric fields

Strong electric fields are known to create biased adatom migration on metallic surfaces. We present a Kinetic Monte Carlo model that can simulate adatom migration on a tungsten (W) surface in electric fields. We validate our model by using it to calculate the drift velocity of the adatom at different fields and temperature and comparing the results with experimental data from the literature. We obtain excellent agreement

Discretization and Representation of a Complex Environment for On-Policy Reinforcement Learning for Obstacle Avoidance for Simulated Autonomous Mobile Agents

In recent years, the demand for digitalization, automation, and smart systems in the airline industry has accelerated. Furthermore, due to the ongoing global pandemic as of 2022, airlines are faced with the challenge of offering flexibility in both cargo and passenger capacity. Studies show that the use of smart products and autonomous agents are expected to play a key part in the digital transformation of the logistics industry. This paper aims to examine the current state-of-the-art in multi-agent systems and reinforcement learning with special interest in intelligent baggage handling systems. How to simplify, implement, and simulate a system of autonomous baggage carts as a software model in order to examine congestion situations will be the main topics of this paper. Furthermore, how the findings from the software model may be applied to real-world scenarios related to Industry 4.0, and baggage handling will also be discussed

Primary stability of cementless threaded acetabular cups at first implantation and in the case of revision regarding micromotions as indicators

The primary stability of cementless total hip endoprosthesis is of vital importance for proximate, long-term osteointegration. The extent of micromotions between implant and acetabulum is an indicator of primary stability. Based on this hypothesis, different cementless hip joint endoprosthesis were studied with regard to their micromotions. The primary stability of nine different cementless threaded acetabular cups was studied in an experimental setup with blocks of rigid foam. The micromotions between implant and implant bearing were therefore evaluated under cyclic, sinusoidal exposure. The blocks of polymer foam were prepared according to the Paprosky defect classifications. The micromotions increased with the increasing degree of the defect with all acetabuli tested. Occasionally coefficients of over 200 mu m were measured. From a defect degree of 3b according to Paprosky, the implants could no longer be appropriately placed. The exterior form of the spherical implants tended to exhibit better coefficients than the conical/parabolic implants

Sports Activity After Short-Stem Hip Arthroplasty

Background: No data are available about the sports activity of patients with bone-conserving short-stem hip implants. Hypothesis: Patients can return to a good level of sports activity after implantation of a short-stem hip implant. Study Design: Case series; Level of evidence, 4. Methods: The sports activity level of 68 patients (76 hips) after short-stem hip arthroplasty was assessed for a minimum of 2 years after implantation. In addition to the clinical examination, a detailed evaluation of the patients’ sports pattern was obtained. Furthermore, the results were analyzed with regard to gender (female and male) and age (55 years). Results: After a mean of 2.7 years, patients showed a Harris Hip Score (HHS) of 93.6, a Western Ontario and McMaster Universities Arthritis Index (WOMAC) score of 9.5, and a University of California, Los Angeles (UCLA) activity score of 7.6, with each individual participating on average in 3.5 different disciplines after surgery compared with 3.9 before surgery. High-impact activities decreased significantly postoperatively, whereas low-impact activities increased significantly. The duration of the sports activities remained stable, while the frequency actually increased. In contrast, men participated preoperatively in more sports than women (4.3 men vs 3.3 women). However, because of a pronounced decrease in high-impact activities by men, both genders participated in an equal number of sports postoperatively (3.5 men vs 3.5 women). Finally, 45% (n = 31) reported at least one activity that they missed. Most of them were disciplines with an intermediate- or high-impact level. Conclusion: Patients with a short-stem hip implant can return to a good level of activity postoperatively. Participation in sports almost reached similar levels as preoperatively but with a shift from high- to low-impact activities. This seems desirable from a surgeon’s point of view but should also be communicated to the patient before hip replacemen

Privata markägares attityder och inställningar till föryngringsfrågor

Even though Sweden is a small country which has a low rate of inhabitants is it one of the worlds leading nations of exporting products from the forest industries. The Importance of a sustainable use of the Swedish forests has been known for many years. In 1903 the first law of forestry were establish. Today the National Board of Forestry carry out inventories of regeneration result. The result of the latest inventory showed that especially the non-industrial private forest owners did not full fill the regeneration work after a clear cut. Five years after the clear cut almost every fifth private forest owners in the region Mälardalen had not done any regeneration activity, even if the law declares that it should be performed after three years. The purpose of this study was to make a qualitative analysis of attitudes of non-industrial private forest owners in the region of Mälardalen with regards to regeneration of forest. The intention is to, from the interviewees point of view and knowledge illuminate why they manage their forests the way they do To catch different attitudes and fullfill the purpose and my personal goal, the study is based upon interviews. The respondent group was 17 forest owners in Mälardalen, which had totally failed or greatly approved, in the National Board of Forestry's inventory of regeneration of harvested areas. The interviews were intended to the different shades of meaning in the answers, in trying to get a complete description of forest owners attitudes concerning regeneration of forests. My opinion is that private forest owners decisions and actions in regeneration activities were very individual and various. Factors which especially seem to impact on their decisions were: Knowledge, interest, lack of time, concern for the next generation, economy, forestry counselors and their level of ambition. Even if some of the interviewed persons had some objections to the form of the information were most of the forest owners satisfied with the amount and availability. My personal reflections are that the information should have such a high appeal that it makes the receiver prioritize the regeneration information.Trots att Sverige till yta och folkmängd är ett litet land tillhör vi de stora aktörerna på världsmarknaden när det gäller export av skogsindustriprodukter. (Skogsindustrin En faktasamling, 2002). Medvetandet om vikten av att uthålligt nyttja de Svenska skogarna har länge funnits. År 1903 antog riksdagen Sveriges första allmänna skogsvårdslag. 1903 års skogsvårdslag hade främst två mål, ett var att återväxtarbetet skulle förbättras och öka i omfattning och det andra berörde skogsvårdstyrelsernas organisation och arbete för hushållning av skogs- resurserna (Eklund och Hamilton, Skogspolitisk historia. Skogsstyrelsens rapport 8A, 2001). Skogsvårsorganisationen genomför ett flertal kontrollåtgärder, en av dem är Polytaxinventeringarna som syftar till att följa upp återväxtresultaten samt hur skogsbruket lever upp till ambitionerna i 1993 års skogspolitik (www.svo.se/projekt/ inventeringar/polytax). Resultatet av den senast utförda undersökningen visade att framförallt de privata markägarna är dåliga på att återbeskoga efter avverkningar Fem år efter avverkning har nästan var femte skogsägare i Mälardalen inte gjort någon aktiv åtgärd alls trots att skogsvårdslagen säger att det ska vara klart tre år efter avverkning. (Skogen 3/01) Syftet med det här projektet är att beskriva skälen till enskilda markägare i Mälardalens handlande med avseende på föryngringsfrågor. Med ledning av detta är sedan avsikten att utifrån markägarens värderingar och kunskaper belysa varför skogen sköts som den gör i dessa frågor. Frågeställningar: • Vilka attityder och inställningar ligger till grund för privata markägare i Mälardalens handlande när det gäller föryngringsfrågor? • I vilken utsträckning finns det tillräcklig och rätt utformat beslutsunderlag/-stöd tillgängligt för markägaren? Eftersom jag personligen har ett brinnande intresse för skog, människor, det sociala mötet samt att jag personligen inte är medveten om någon liknande undersökning i ämnet, var det mer en självklarhet att jag valde att använda mig av en kvalitativ forskningsintervju än någon annan metod. Syftet med den kvalitativa forskningsintervjun är att man genom samtal ska få ökad förståelse för den intervjuades livssituation ur dennes egen synvinkel. Det rör sig om ett samspel och utbyte av synpunkter och attityder mellan två personer som samtalar om ett ämne av gemensamt intresse. (Kvale,S 1997). För att få så stor spridning som möjligt inom min respondent grupp och öka chanserna att de medverkande markägarna i så hög grad som möjligt skulle representera varandras motsatser när det gällde attityder och inställningar till föryngringsåtgärder utgick jag ifrån Skogsvårdsorganisationens polytaxundersökning. Den ena gruppen som jag valde att intervjua var fullständigt godkända på det kontrollerade hygget med ett plantantal, oavsett åtgärd som var högt över lagens gräns för godkänt. Den andra gruppen bestod av markägare som hade ett hygge som var helt underkänt och där ingen föryngringsåtgärd var utförd. Skogsvårdsorganisationens region Mälardalen bestod innan omorganisationen av 8st distrikt vilket utgjorde den geografiska fördelningen inom regionen för intervjuerna. Storleken på de 2 medverkande fastigheterna varierade mellan 40-700 ha. De flesta var dock mellan 50-120ha. Åldern på de medverkande rymdes alla uppskattningsvis inom intervallet 30-75 år. Viktigt att belysa är syftet, vilket är att utifrån mina erfarenheter och kunskaper göra en subjektiv beskrivning av markägare i Mälardalens handlande i föryngringsfrågor som en grupp. Syftet med de två markägarkategorierna är inte att undersöka dem var för sig utan endast för att eftersträva största möjliga spridning i gruppen som helhet, vilket är viktigt i kvalitativa undersökningar. Det eftersträvade klimatet mellan parterna gör också att intervjun mer ter sig som ett samtal med mer korta frågor kring temana med långa och beskrivande svar från markägaren, än många frågor och korta svar. Innan jag genomförde de 17 intervjuerna utförde jag även en mer inofficiell test intervju. Intervjuerna kretsade kring 11 teman: 1. Ägarförhållanden 2. Skogsvård 3. Ekonomi 4. Skogsvårdslagen 5. Påverkande faktorer 6. Föryngring 7. Skogliga aktörer 8. Information/Utbildning 9. Kunskap 10. Framtiden 11. Övrigt Alla intervjuer utfördes av mig personligen på skogsägarens fastighet, detta för att få en så avslappnad miljö som möjligt. Intervjuerna tog i alla utom ett fall minst en timme. Samtalen spelades in på band och skrevs sedan ned ordagrant. Vid utskriften av bandupptagningarna utelämnade jag även viss information för att skydda de intervjuades integritet. Under de 17 intervjuerna som behandlats i resultatdelen var det några ämnen som var mer centrala än andra. Dessa ämnen utgjorde grunden under samtalen och återkom vid upprepade tillfällen under intervjuerna. De ämnesområden som jag, utifrån detta, har valt att koncentrera diskussionen kring är: • Påverkande faktorer för beslutsfattande i föryngringsfrågor • Föryngring • Skogliga aktörer och Skogsvårdslagen • Kunskap och information Påverkande faktorer Jag uppfattade det som att det främst var tid, ekonomi, skogliga aktörer, omtanke för nästa generation, kunskap och information samt engagemang och ambitionsnivå som var de viktigaste påverkande faktorern

Baseline scenario(s) for muon collider proton driver

This paper gives an overview of the various muon collider scenarios and the requirements they put on the Proton Driver. The required proton power is about 4-6MW in all the scenarios, but the bunch repetition rate varies between 12 and 65Hz. Since none of the muon collider scenarios have been simulated end-to-end, it would be advisable to plan for an upgrade path to around 10MW. Although the proton driver energy is flexible, cost arguments seems to favor a relatively low energy. In particular, at Fermilab 8GeV seems most attractive, partly due to the possibility of reusing the three existing fixed energy storage rings for bunch manipulations

Atomistic behavior of metal surfaces under high electric fields

Combining classical electrodynamics and density functional theory (DFT) calculations, we develop a general and rigorous theoretical framework that describes the energetics of metal surfaces under high electric fields. We show that the behavior of a surface atom in the presence of an electric field can be described by the polarization characteristics of the permanent and field-induced charges in its vicinity. We use DFT calculations for the case of a W adatom on a W{110} surface to confirm the predictions of our theory and quantify its system-specific parameters. Our quantitative predictions for the diffusion of W-on-W{110} under field are in good agreement with experimental measurements. This work is a crucial step towards developing atomistic computational models of such systems for long-term simulations.Peer reviewe

An individual-based network model to evaluate interventions for controlling pneumococcal transmission

<p>Abstract</p> <p>Background</p> <p><it>Streptococcus pneumoniae </it>is a major cause of morbidity and mortality worldwide, but also a common colonizer of the upper respiratory tract. The emergence and spread of antibiotic resistant pneumococcal strains has threatened effective therapy. The long-term effects of measures aiming to limit pneumococcal spread are poorly understood. Computational modeling makes it possible to conduct virtual experiments that are impractical to perform in real life and thereby allows a more full understanding of pneumococcal epidemiology and control efforts.</p> <p>Methods</p> <p>We have developed a contact network model to evaluate the efficacy of interventions aiming to control pneumococcal transmission. Demographic data from Sweden during the mid-2000s were employed. Analyses of the model's parameters were conducted to elucidate key determinants of pneumococcal spread. Also, scenario simulations were performed to assess candidate control measures.</p> <p>Results</p> <p>The model made good predictions of previous findings where a correlation has been found between age and pneumococcal carriage. Of the parameters tested, group size in day-care centers was shown to be one of the most important factors for pneumococcal transmission. Consistent results were generated from the scenario simulations.</p> <p>Conclusion</p> <p>We recommend, based on the model predictions, that strategies to control pneumococcal disease and organism transmission should include reducing the group size in day-care centers.</p

Protease gene families in Populus and Arabidopsis

BACKGROUND: Proteases play key roles in plants, maintaining strict protein quality control and degrading specific sets of proteins in response to diverse environmental and developmental stimuli. Similarities and differences between the proteases expressed in different species may give valuable insights into their physiological roles and evolution. RESULTS: We have performed a comparative analysis of protease genes in the two sequenced dicot genomes, Arabidopsis thaliana and Populus trichocarpa by using genes coding for proteases in the MEROPS database [1] for Arabidopsis to identify homologous sequences in Populus. A multigene-based phylogenetic analysis was performed. Most protease families were found to be larger in Populus than in Arabidopsis, reflecting recent genome duplication. Detailed studies on e.g. the DegP, Clp, FtsH, Lon, rhomboid and papain-Like protease families showed the pattern of gene family expansion and gene loss was complex. We finally show that different Populus tissues express unique suites of protease genes and that the mRNA levels of different classes of proteases change along a developmental gradient. CONCLUSION: Recent gene family expansion and contractions have made the Arabidopsis and Populus complements of proteases different and this, together with expression patterns, gives indications about the roles of the individual gene products or groups of proteases