Automatic Filters for the Detection of Coherent Structure in Spatiotemporal Systems

Most current methods for identifying coherent structures in spatially-extended systems rely on prior information about the form which those structures take. Here we present two new approaches to automatically filter the changing configurations of spatial dynamical systems and extract coherent structures. One, local sensitivity filtering, is a modification of the local Lyapunov exponent approach suitable to cellular automata and other discrete spatial systems. The other, local statistical complexity filtering, calculates the amount of information needed for optimal prediction of the system's behavior in the vicinity of a given point. By examining the changing spatiotemporal distributions of these quantities, we can find the coherent structures in a variety of pattern-forming cellular automata, without needing to guess or postulate the form of that structure. We apply both filters to elementary and cyclical cellular automata (ECA and CCA) and find that they readily identify particles, domains and other more complicated structures. We compare the results from ECA with earlier ones based upon the theory of formal languages, and the results from CCA with a more traditional approach based on an order parameter and free energy. While sensitivity and statistical complexity are equally adept at uncovering structure, they are based on different system properties (dynamical and probabilistic, respectively), and provide complementary information.Comment: 16 pages, 21 figures. Figures considerably compressed to fit arxiv requirements; write first author for higher-resolution version

Surveillance of climate-sensitive zoonotic diseases: Leptospirosis at livestock slaughterhouses in three regions of Uganda

Leptospirosis is an important bacterial zoonosis worldwide and is disproportionately associated with low-income settings and with extreme weather events due to climate change. Transmission to humans often occurs when infected rodents and domestic animals contaminate the environment via urine as the bacteria preferentially colonise kidneys. Surveillance of leptospirosis at slaughterhouses can therefore be useful in providing information on vast areas of a country and screening for diseases that are not considered during animal inspections. We determined the prevalence of Leptospira bacteria in the kidneys of 2,030 livestock kidney samples (820 cattle, 761 pigs, 335 goats, 114 sheep), and 117 small mammals by realtime PCR in a cross-sectional survey of slaughter facilities in three regions in Uganda. We extracted DNA and performed real-time polymerase chain reaction (PCR) tests targeting the lipL32 gene for pathogenic leptospires. Positive samples with cycle threshold values below 38 were further characterised using single locus sequence typing (SLST) to determine likely genomospecies. PCR products were sequenced by Eurofins Genomics (Ebersberg, Germany) and identification of genomospecies was done using the basic local alignment search tool (BLAST). Multi-locus sequencing typing (MLST) was performed on selected SLST-positive samples to determine sequence types (ST) and likely serogroups. The allelic profiles were analysed using Bionumerics software and the sequence types were determined using the PubMLST database. An overall prevalence of pathogenic leptospires of 2.58 % (95 % confidence intervals [CI]: 1.89–3.42) was observed, with sheep having the highest prevalence (6.12 % CI: 2.69–12.89), followed by cattle (4.25 %, 95 % CI: 2.91–5.98), goats (2.08 %, 95 % CI=0.91–4.38), and pigs (0.46 %, 95 % CI = 0.12–1.31) in decreasing order. The genomospecies L. borgpetersenii (11 in cattle and one in goat), L. kirschneri (five in cattle and four in sheep) and L. interrogans (one in a pig) were determined. Preliminary MLST results on one sample reveal L. kirschneri ST62 which is related to serogroup Grippotyphosa. Surveillance of important zoonoses using slaughterhouses as sentinels has the potential to offer essential information on the epidemiology of important zoonotic diseases in Uganda

A gentle push towards improved hygiene and food safety through ‘nudge’ interventions

Most of the perishable food in low- and middle-income countries is sold in informal markets where food handlers are not usually trained in good hygienic practices. There are different approaches to improve food safety in those markets, some of which include capacity building. However, one-off trainings are not usually sustainable as behaviours are deeply rooted and often lead to unconscious practices that can increase risk of food contamination. Close follow-up is intense in terms of human and financial resources. Nudges have been described to influence behaviour with varying results, partly depending on whether they have been imposed on or co-created with the end-users. In this study we describe the human-centred-design process from identifying critical control points between slaughter and retail to co-creating nudges that could potentially lead to better compliance of meat handlers in Uganda with good hygienic practices. Three of the WHO “Five Keys To Safer Food” were selected as the target behaviours to improve. The qualitative research was implemented in the greater Kampala area between October 2020 to December 2021 and involved 119 meat handlers, pork joint customers, food safety and veterinary technical experts and over 20 project stakeholders. Findings from the initial ‘explore’ phase generated a number of insights on meat handlers’ perceptions and attitudes that were later used to generate ideas and solutions in cocreating nudges during the ‘experiment’ phase: 1) Meat handlers eat the pork they handle at work and have low risk perception; 2) Meat handlers feel their practices are acceptable; 3) Meat handlers see ‘broken windows’ which set the norm for unhygienic behaviour; 4) Meat handlers follow the path of least resistance; 5) Meat handlers keep up appearances for customers; and 6) Owners want to see returns on hygienic investments. Fourty-two early prototypes were co-created with potential end users and after several iterations, two nudge kits emerged, e.g. the “Keep Clean Loop” and the “Tricolour Kitchen”. In a subsequent pilot test we assessed if the nudges help reducing the burden of foodborne pathogens and if behaviour of meat handlers changes sustainably

Old World megadroughts and pluvials during the Common Era

Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability

Autoregulation of von Willebrand factor function by a disulfide bond switch

Force-dependent binding of platelet glycoprotein Ib (GPIb) receptors to plasma von Willebrand factor (VWF) plays a key role in hemostasis and thrombosis. Previous studies have suggested that VWF activation requires force-induced exposure of the GPIb binding site in the A1 domain that is autoinhibited by the neighboring A2 domain. However, the biochemical basis of this “mechanopresentation” remains elusive. From a combination of protein chemical, biophysical, and functional studies, we find that the autoinhibition is controlled by the redox state of an unusual disulfide bond near the carboxyl terminus of the A2 domain that links adjacent cysteine residues to form an eight-membered ring. Only when the bond is cleaved does the A2 domain bind to the A1 domain and block platelet GPIb binding. Molecular dynamics simulations indicate that cleavage of the disulfide bond modifies the structure and molecular stresses of the A2 domain in a long-range allosteric manner, which provides a structural explanation for redox control of the autoinhibition. Significantly, the A2 disulfide bond is cleaved in ~75% of VWF subunits in healthy human donor plasma but in just ~25% of plasma VWF subunits from heart failure patients who have received extracorporeal membrane oxygenation support. This suggests that the majority of plasma VWF binding sites for platelet GPIb are autoinhibited in healthy donors but are mostly available in heart failure patients. These findings demonstrate that a disulfide bond switch regulates mechanopresentation of VWF.: This study was supported by grants from the National Health and Medical Research Council of Australia (P.J.H.), Royal College of Pathologists Foundation Kanematsu/Novo Nordisk Research Award (F.P. and L.J.), Diabetes Australia Research Trust grant G179720 and Sydney Medical School Early-Career Researcher Kickstart Grant (L.J.), National Heart Foundation of Australia Postdoctoral Fellowship (101285) (L.J.) and British Heart Foundation Intermediate Basic Science Research Fellowship (FS/11/51/28920) (B.M.L.), Deutsche Forschungsgemeinschaft (research unit FOR 1543 to C.A.-S., C.B., and F.G.), the Center for Modelling and Simulation in the Biosciences postdoctoral program of the Heidelberg University (A.B.), and the Klaus Tschira Foundation (F.G.). B.L. was supported by the Dutch Thrombosis Foundation through grant number 2016-03.