54 research outputs found

    Ratchet-induced variations in bulk states of an active ideal gas

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    We study the distribution of active, noninteracting particles over two bulk states separated by a ratchet potential. By solving the steady-state Smoluchowski equations in a flux-free setting, we show that the ratchet potential affects the distribution of particles over the bulks, and thus exerts an influence of infinitely long range. As we show, crucial for having such a long-range influence is an external potential that is nonlinear. We characterize how the difference in bulk densities depends on activity and on the ratchet potential, and we identify power law dependencies on system parameters in several limiting cases. While weakly active systems are often understood in terms of an effective temperature, we present an analytical solution that explicitly shows that this is not possible in the current setting. Instead, we rationalize our results by a simple transition state model, that presumes particles to cross the potential barrier by Arrhenius rates modified for activity. While this model does not quantitatively describe the difference in bulk densities for feasible parameter values, it does reproduce - in its regime of applicability - the complete power law behavior correctly.Comment: 11 pages, 6 figure

    In search of a precursor for crystal nucleation of hard and charged colloids

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    The interplay between crystal nucleation and the structure of the metastable fluid has been a topic of significant debate over recent years. In particular, it has been suggested that even in simple model systems such as hard or charged colloids, crystal nucleation might be foreshadowed by significant fluctuations in local structure around the location where the first nucleus arises. We investigate this using computer simulations of spontaneous nucleation events in both hard and charged colloidal particles. To detect local structural variations, we use both standard and unsupervised machine learning methods capable of finding hidden structures in the metastable fluid phase. We track numerous nucleation events for the face-centered cubic and body-centered cubic crystal on a local level, and demonstrate that all signs of crystallinity emerge simultaneously from the very start of the nucleation process. We thus conclude that there is no precursor for the nucleation of charged colloids

    Point Defects in Crystals of Charged Colloids

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    Charged colloidal particles - both on the nano and micron scales - have been instrumental in enhancing our understanding of both atomic and colloidal crystals. These systems can be straightforwardly realized in the lab, and tuned to self-assemble into body-centered cubic (BCC) and face-centered cubic (FCC) crystals. While these crystals will always exhibit a finite number of point defects, including vacancies and interstitials - which can dramatically impact their material properties - their existence is usually ignored in scientific studies. Here, we use computer simulations and free-energy calculations to characterize vacancies and interstitials in both FCC and BCC crystals of point-Yukawa particles. We show that, in the BCC phase, defects are surprisingly more common than in the FCC phase, and the interstitials manifest as so-called crowdions: an exotic one-dimensional defect proposed to exist in atomic BCC crystals. Our results open the door to directly observing these elusive defects in the lab.Comment: 8 pages, 4 figure

    The ERA Registry Annual Report 2019 : summary and age comparisons

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    Background Data on renal replacement therapy (RRT) for end-stage renal disease were collected by the European Renal Association (ERA) Registry via national and regional renal registries in Europe and countries bordering the Mediterranean Sea. This article provides a summary of the 2019 ERA Registry Annual Report, including data from 34 countries and additional age comparisons. Methods Individual patient data for 2019 were provided by 35 registries and aggregated data by 17 registries. Using these data, the incidence and prevalence of RRT, the kidney transplantation activity and the survival probabilities were calculated. Results In 2019, a general population of 680.8 million people was covered by the ERA Registry. Overall, the incidence of RRT was 132 per million population (p.m.p.). Of these patients, 62% were men, 54% were >= 65 years of age and 21% had diabetes mellitus as primary renal disease (PRD), and 84% had haemodialysis (HD), 11% had peritoneal dialysis (PD) and 5% had pre-emptive kidney transplantation as an initial treatment modality. The overall prevalence of RRT on 31 December 2019 was 893 p.m.p., with 58% of patients on HD, 5% on PD and 37% living with a kidney transplant. The overall kidney transplant rate was 35 p.m.p. and 29% of the kidney grafts were from a living donor. The unadjusted 5-year survival probability was 42.3% for patients commencing dialysis, 86.6% for recipients of deceased donor grafts and 94.4% for recipients of living donor grafts in the period 2010-14. When comparing age categories, there were substantial differences in the distribution of PRD, treatment modality and kidney donor type, and in the survival probabilities.Peer reviewe

    The European Renal Association - European Dialysis and Transplant Association (ERA-EDTA) Registry Annual Report 2016 : a summary

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    Background. This article summarizes the ERA-EDTA Registry's 2016 Annual Report, by describing the epidemiology of renal replacement therapy (RRT) for end-stage renal disease (ESRD) in 2016 within 36 countries. Methods. In 2017 and 2018, the ERA-EDTA Registry received data on patients undergoing RRT for ESRD in 2016 from 52 national or regional renal registries. In all, 32 registries provided individual patient data and 20 provided aggregated data. The incidence and prevalence of RRT and the survival probabilities of these patients were determined. Results. In 2016, the incidence of RRT for ESRD was 121 per million population (pmp), ranging from 29 pmp in Ukraine to 251 pmp in Greece. Almost two-thirds of patients were men, over half were aged >= 65 years and almost a quarter had diabetes mellitus as their primary renal diagnosis. Treatment modality at the start of RRT was haemodialysis for 84% of patients. On 31 December 2016, the prevalence of RRT was 823 pmp, ranging from 188 pmp in Ukraine to 1906 pmp in Portugal. In 2016, the transplant rate was 32 pmp, varying from 3 pmp in Ukraine to 94 pmp in the Spanish region of Catalonia. For patients commencing RRT during 2007-11, the 5-year unadjusted patient survival probability on all RRT modalities combined was 50.5%. For 2016, the incidence and prevalence of RRT were higher among men (187 and 1381 pmp) than women (101 and 827 pmp), and men had a higher rate of kidney transplantation (59 pmp) compared with women (33 pmp). For patients starting dialysis and for patients receiving a kidney transplant during 2007-11, the adjusted patient survival probabilities appeared to be higher for women than for men.Peer reviewe

    The ERA-EDTA Registry Annual Report 2017 : a summary

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    Background. This article presents a summary of the 2017 Annual Report of the European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) Registry and describes the epidemiology of renal replacement therapy (RRT) for end-stage renal disease (ESRD) in 37 countries. Methods. The ERA-EDTA Registry received individual patient data on patients undergoing RRT for ESRD in 2017 from 32 national or regional renal registries and aggregated data from 21 registries. The incidence and prevalence of RRT, kidney transplantation activity and survival probabilities of these patients were calculated. Results. In 2017, the ERA-EDTA Registry covered a general population of 694 million people. The incidence of RRT for ESRD was 127 per million population (pmp), ranging from 37 pmp in Ukraine to 252 pmp in Greece. A total of 62% of patients were men, 52% were >= 65 years of age and 23% had diabetes mellitus as the primary renal disease. The treatment modality at the onset of RRT was haemodialysis for 85% of patients. On 31 December 2017, the prevalence of RRT was 854 pmp, ranging from 210 pmp in Ukraine to 1965 pmp in Portugal. The transplant rate in 2017 was 33 pmp, ranging from 3 pmp in Ukraine to 103 pmp in the Spanish region of Catalonia. For patients commencing RRT during 2008-12, the unadjusted 5-year patient survival probability for all RRT modalities combined was 50.8%.Peer reviewe

    Renal replacement therapy in Europe : A summary of the 2011 ERA-EDTA Registry Annual Report

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    BackgroundThis article provides a summary of the 2011 ERA-EDTA Registry Annual Report (available at www.era-edta-reg.org).MethodsData on renal replacement therapy (RRT) for end-stage renal disease (ESRD) from national and regional renal registries in 30 countries in Europe and bordering the Mediterranean Sea were used. From 27 registries, individual patient data were received, whereas 17 registries contributed data in aggregated form. We present the incidence and prevalence of RRT, and renal transplant rates in 2011. In addition, survival probabilities and expected remaining lifetimes were calculated for those registries providing individual patient data.ResultsThe overall unadjusted incidence rate of RRT in 2011 among all registries reporting to the ERA-EDTA Registry was 117 per million population (pmp) (n = 71.631). Incidence rates varied from 24 pmp in Ukraine to 238 pmp in Turkey. The overall unadjusted prevalence of RRT for ESRD on 31 December 2011 was 692 pmp (n = 425 824). The highest prevalence was reported by Portugal (1662 pmp) and the lowest by Ukraine (131 pmp). Among all registries, a total of 22 814 renal transplantations were performed (37 pmp). The highest overall transplant rate was reported from Spain, Cantabria (81 pmp), whereas the highest rate of living donor transplants was reported from Turkey (39 pmp). For patients who started RRT between 2002 and 2006, the unadjusted 5-year patient survival on RRT was 46.8% [95% confidence interval (CI) 46.6-47.0], and on dialysis 39.3% (95% CI 39.2-39.4). The unadjusted 5-year patient survival after the first renal transplantation performed between 2002 and 2006 was 86.7% (95% CI 86.2-87.2) for kidneys from deceased donors and 94.3% (95% CI 93.6-95.0) for kidneys from living donors.publishersversionPeer reviewe

    The ERA Registry Annual Report 2021:a summary

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    BackgroundThe European Renal Association (ERA) Registry collects data on kidney replacement therapy (KRT) in patients with end-stage kidney disease (ESKD). This paper is a summary of the ERA Registry Annual Report 2021, including a comparison across treatment modalities.MethodsData was collected from 54 national and regional registries from 36 countries, of which 35 registries from 18 countries contributed individual patient data and 19 registries from 19 countries contributed aggregated data. Using this data, incidence and prevalence of KRT, kidney transplantation rates, survival probabilities and expected remaining lifetimes were calculated.ResultsIn 2021, 533.2 million people in the general population were covered by the ERA Registry. The incidence of KRT was 145 per million population (pmp). In incident patients, 55% were 65 years or older, 64% were male, and the most common primary renal disease (PRD) was diabetes (22%). The prevalence of KRT was 1040 pmp. In prevalent patients, 47% were 65 years or older, 62% were male, and the most common PRDs were diabetes and glomerulonephritis/sclerosis (both 16%). On 31 December 2021, 56% of patients received haemodialysis, 5% received peritoneal dialysis, and 39% were living with a functioning graft. The kidney transplantation rate in 2021 was 37 pmp, a majority coming from deceased donors (66%). For patients initiating KRT between 2012–2016, 5-year survival probability was 52%. Compared to the general population, life expectancy was 65% and 68% shorter for males and females receiving dialysis, and 40% and 43% shorter for males and females living with a functioning graft

    The European Renal Association - European Dialysis and Transplant Association Registry Annual Report 2014 : a summary

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    Background: This article summarizes the European Renal Association - European Dialysis and Transplant Association Registry's 2014 annual report. It describes the epidemiology of renal replacement therapy (RRT) for end-stage renal disease (ESRD) in 2014 within 35 countries. Methods: In 2016, the ERA-EDTA Registry received data on patients who in 2014 where undergoing RRT for ESRD, from 51 national or regional renal registries. Thirty-two registries provided individual patient level data and 19 provided aggregated patient level data. The incidence, prevalence and survival probabilities of these patients were determined. Results: In 2014, 70 953 individuals commenced RRT for ESRD, equating to an overall unadjusted incidence rate of 133 per million population (pmp). The incidence ranged by 10-fold; from 23 pmp in the Ukraine to 237 pmp in Portugal. Of the patients commencing RRT, almost two-thirds were men, over half were aged >= 65 years and a quarter had diabetes mellitus as their primary renal diagnosis. By day 91 of commencing RRT, 81% of patients were receiving haemodialysis. On 31 December 2014, 490 743 individuals were receiving RRT for ESRD, equating to an unadjusted prevalence of 924 pmp. This ranged throughout Europe by more than 10-fold, from 157 pmp in the Ukraine to 1794 pmp in Portugal. In 2014, 19 406 kidney transplantations were performed, equating to an overall unadjusted transplant rate of 36 pmp. Again this varied considerably throughout Europe. For patients commencing RRT during 2005-09, the 5-year-adjusted patient survival probabilities on all RRT modalities was 63.3% (95% confidence interval 63.0-63.6). The expected remaining lifetime of a 20-to 24-year-old patient with ESRD receiving dialysis or living with a kidney transplant was 21.9 and 44.0 years, respectively. This was substantially lower than the 61.8 years of expected remaining lifetime of a 20-year-old patient without ESRD.Peer reviewe
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