Fixation and escape times in stochastic game learning

Evolutionary dynamics in finite populations is known to fixate eventually in the absence of mutation. We here show that a similar phenomenon can be found in stochastic game dynamical batch learning, and investigate fixation in learning processes in a simple 2x2 game, for two-player games with cyclic interaction, and in the context of the best-shot network game. The analogues of finite populations in evolution are here finite batches of observations between strategy updates. We study when and how such fixation can occur, and present results on the average time-to-fixation from numerical simulations. Simple cases are also amenable to analytical approaches and we provide estimates of the behaviour of so-called escape times as a function of the batch size. The differences and similarities with escape and fixation in evolutionary dynamics are discussed.Comment: 19 pages, 9 figure

NH4+ secretion in inner medullary collecting duct in potassium deprivation: Role of colonic H+-K+-ATPase

NH4+ secretion in inner medullary collecting duct in potassium deprivation: Role of colonic H+-K+-ATPase.BackgroundIn K+ deprivation (KD), gastric (g) H+-K+-ATPase (HKA) is suppressed, whereas colonic (c) HKA is induced in the terminal inner medullary collecting duct (IMCD). We hypothesized that in KD, cHKA is induced and can mediate the secretion of NH4+.MethodsRats were sacrificed after 2, 3, 6, or 14 days on regular (NML) or K+-free (KD) diet. mRNA expression of HKA isoforms in terminal inner medulla was examined and correlated with NH4+ secretion in perfused IMCD in vitro.ResultsUrinary NH4+ excretion increased after K+-free diet for six days. In terminal inner medulla, cHKA expression was strongly induced, whereas gHKA expression was decreased. NH4+ secretion increased by 62% in KD (JtNH4+ 0.57 vs. 0.92 pmol/min/mm tubule length, P < 0.001). Ouabain (1 mM) in perfusate inhibited NH4+ secretion in KD by 45% (P < 0.002) but not in NML. At luminal pH 7.7, which inhibits NH3 diffusion, NH4+ secretion in IMCD was 140% higher in KD (0.36 vs. 0.15, P < 0.03) and was sensitive to ouabain. ROMK-1 mRNA expression was induced in parallel with cHKA in inner medulla.ConclusionsThese data suggest that in KD, cHKA replaces gHKA and mediates enhanced secretion of NH4+ (and H+) into the lumen facilitated by K+ recycling through ROMK-1

Role of the loop segment in the urinary concentrating defect of hypercalcemia

Role of the loop segment in the urinary concentrating defect of hypercalcemia. Hypercalcemia is associated with impaired urinary concentrating ability. To explore the mechanism(s) by which hypercalcemia impairs chloride transport in the loop of Henle, we carried out in vivo microperfusion of the loop segment in Sprague–Dawley rats rendered acutely hypercalcemie (12.1 ± 0.1 mg/dliter) by calcium gluconate infusion. Control rats were infused with sodium gluconate and had normal plasma calcium (8.0 ± 0.2 mg/dliter). Compared to control, fractional chloride reabsorption was decreased (61 ± 4 to 50 ± 3%; P < 0.05) and early distal chloride increased 74 ± 6 to 98 ± 3 mEq/liter (P < 0.001) in hypercalcemia. During hypercalcemia, infusion of verapamil failed to increase fractional chloride reabsorption (49 ± 4%; P < 0.05) or decrease early distal chloride (95 ± 2; P < 0.05) toward control values. Similarly, indomethacin did not improve fractional chloride reabsorption (48 ± 4%; P < 0.05) or distal chloride concentration (93 ± 7; P < 0.05). In control rats infused with Ringers HCO3, the addition of calcium 8.0 mEq/liter to the perfusate increased early distal calcium (0.22 to 3.11 mEq/liter) but was associated with no change in fractional chloride reabsorption (-6 ± 6%) and a slight decrease in early distal chloride (-9 ± 3 mEq/liter; P < 0.05). These data are consistent with the hypothesis that an elevated plasma, not luminal calcium, concentration impairs chloride reabsorption in the loop segment, primarily the ADH–stimulated component. This may have an important role in the urinary concentrating defect of hypercalcemia

Team Robockey: Final Design Report

This report describes the design of the Trinity Robockey infrastructure and the team of two autonomous robots. The methodology for testing the effectiveness of the project\u27s final design is detailed. These tests are designed to provide evidence of whether or not the Robockey met the objectives outlined in the project charter. The results, final conclusions, and recommendations are provided

Effect of urinary pH and diatrizoate on Bence Jones protein nephrotoxicity in the rat

Effect of urinary pH and diatrizoate on Bence Jones protein nephrotoxicity in the rat. Both low urinary pH and radiocontrast agents may intensify myeloma nephrotoxicity. To study the effects of these factors, we determined inulin clearances (CIn) before and after infusions of human Bence Jones protein (BJP) in male Sprague-Dawley rats in a dose previously shown to be nephrotoxic. Rats that drank 0.15 M NaHCO3 for 48 hr before study had no change in CIn (+ 3 ± 20%) after BJP unlike those that drank 0.15 M NH4Cl (- 33 ± 14%, P < 0.05); urinary pH differed (7.6 ± 0.1 vs. 6.2 ± 0.1, P < 0.05), but urinary flow rates did not. The acidifying regimen was used in all subsequent groups. Infusion of diatrizoate (DTZ) after BJP produced a further decrease in CIn (- 85 ± 8%, P < 0.05). In contrast, infusion of albumin, which raised plasma protein concentration to that seen in BJP-infused rats, did not change CIn (+ 39 ± 17%). Infusion of beta-lactoglobulin also led to a greater decrease in CIn after DTZ (- 35 ± 9 vs. - 67 ± 8%, P < 0.05), but myoglobin did not (- 58 ± 7 vs. - 54 ± 12%). Urinary pH and flow rate did not differ between any DTZ-infused group and its appropriate control. These data suggest that aciduria independent of urinary flow rate increases the nephrotoxicity of BJP. In this setting, DTZ further intensifies the nephrotoxicity of BJP as well as some but not all filterable proteins.Effet du pH urinaire et du diatrizoate sur la néphrotoxicité de la protéine de Bence Jones chez le rat. Un pH urinaire bas et les produits de contraste peuvent accroître la néphrotoxité du myélome. Pour étudier les effets de ces facteurs, nous avons déterminé les clearances de l'inuline (CIn) avant et après perfusion de protéine de Bence Jones humaine (BJP) chez des rats mâles Sprague-Dawley à dose préalablement montrée néphrotoxique. Les rats qui buvaient 0,15 M NaHCO3 pendant 48 hr avant l'étude n'avaient pas de modification de CIn (+ 3 ± 20%) après BJP à la différence de ceux qui buvaient 0,15 M NH4Cl (- 33 ± 14%, P < 0,05); les pH urinaires différaient (7,6 ± 0,1 contre 6,2 ± 0,1, P < 0,05), mais non les débits urinaires. Le régime acidifiant a été utilisé chez tous les groupes ultérieurs. La perfusion de diatrizoate (DTZ) après BJP a entraîné une diminution supplémentaire de CIn (- 85 ± 8%, P < 0,05). A l'opposé une perfusion d'albumine, qui augmentait la protidémie à la valeur observée chez les rats perfusés avec BJP ne modifiait pas CIn (+ 39 ± 17%). Une perfusion de béta-lactoglobuline a également entraîné une plus forte baisse de CIn après DTZ (- 35 ± 9 contre - 67 ± 8%, P < 0,05), mais non de la myoglobine (- 58 ± 7 contre - 54 ± 12%). Le pH et le débit urinaires ne différaient pas entre aucun des groupes perfusés par le DTZ et leur contrôle approprié. Ces données suggèrent que l'acidurie, indépendamment du débit urinaire, augmente la néphrotoxicité de la BJP. Dans ce schéma, DTZ accentue encore la néphrotoxicité de la BJP, de même que certaines, mais non toutes les protéines filtrables

Meta-Analysis Reveals Challenges and Gaps for Genome-to-Phenome Research Underpinning Plant Drought Response

Severe drought conditions and extreme weather events are increasing worldwide with climate change, threatening the persistence of native plant communities and ecosystems. Many studies have investigated the genomic basis of plant responses to drought. However, the extent of this research throughout the plant kingdom is unclear, particularly among species critical for the sustainability of natural ecosystems. This study aimed to broaden our understanding of genome-to-phenome (G2P) connections in drought-stressed plants and identify focal taxa for future research. Bioinformatics pipelines were developed to mine and link information from databases and abstracts from 7730 publications. This approach identified 1634 genes involved in drought responses among 497 plant taxa. Most (83.30%) of these species have been classified for human use, and most G2P interactions have been described within model organisms or crop species. Our analysis identifies several gaps in G2P research literature and database connectivity, with 21% of abstracts being linked to gene and taxonomy data in NCBI. Abstract text mining was more successful at identifying potential G2P pathways, with 34% of abstracts containing gene, taxa, and phenotype information. Expanding G2P studies to include non-model plants, especially those that are adapted to drought stress, will help advance our understanding of drought responsive G2P pathways

Adaptive optics tracking and pushing system for space debris manoeuvre

As space debris in lower Earth orbits are accumulating, techniques to lower the risk of space debris collisions must be developed. Within the context of the Space Environment Research Centre (SERC), the Australian National University (ANU) is developing an adaptive optics system for tracking and pushing space debris. The strategy is to pre-condition a laser launched from a 1.8 m telescope operated by Electro Optics Systems (EOS) on Mount Stromlo, Canberra and direct it at an object to perturb its orbit. Current progress towards implementing this experiment, which will ensure automated operation between the telescope and the adaptive optics system, will be presented.The authors would like to acknowledge the support of the Cooperative Research Centre for Space Environment Management (SERC Limited) through the Australian Government’s Cooperative Research Centre Programm

Elementary modelling and behavioural analysis for emergency evacuations using social media

YesSocial media usage in evacuations and emergency management represents a rapidly expanding field of study. Our paper thus provides quantitative insight into a serious practical problem. Within this context a behavioural approach is key. We discuss when facilitators should consider model-based interventions amid further implications for disaster communication and emergency management. We model the behaviour of individual people by deriving optimal contrarian strategies. We formulate a Bayesian algorithm which enables the optimal evacuation to be conducted sequentially under worsening conditions.Supported by EPSRC (IDEAS Factory - Game theory and adaptive networks for smart evacuations, EP/I005765/1

Measurement of the tau lepton lifetime

The mean lifetime of the tau lepton is measured in a sample of 25700 tau pairs collected in 1992 with the ALEPH detector at LEP. A new analysis of the 1-1 topology events is introduced. In this analysis, the dependence of the impact parameter sum distribution on the daughter track momenta is taken into account, yielding improved precision compared to other impact parameter sum methods. Three other analyses of the one- and three-prong tau decays are updated with increased statistics. The measured lifetime is 293.5+/-3.1+/-1.7 fs. Including previous (1989-1991) ALEPH measurements, the combined tau lifetime is 293.7+/-2.7+/-1.6 fs