26 research outputs found
Finite size effects and metastability in zero-range condensation
We study zero-range processes which are known to exhibit a condensation transition, where above a critical density a non-zero fraction of all particles accumulates on a single lattice site. This phenomenon has been a subject of recent research interest and is well understood in the thermodynamic limit. The system shows large finite size effects, and we observe a switching between metastable fluid and condensed phases close to the critical point, in contrast to the continuous limiting behaviour of relevant observables. We describe the leading order finite size effects and establish a discontinuity near criticality in a rigorous scaling limit. We also characterise the metastable phases using a current matching argument and an extension of the fluid phase to supercritical densities. This constitutes an interesting example where the thermodynamic limit fails to capture essential parts of the dynamics, which are particularly relevant in applications with moderate system sizes such as traffic flow or granular clustering
Modified-release hydrocortisone is associated with lower plasma renin activity in patients with salt-wasting congenital adrenal hyperplasia.
OBJECTIVE: Poorly controlled salt-wasting (SW) congenital adrenal hyperplasia (CAH) patients often require high 9α-fluorocortisol doses as they show high levels of 17-hydroxyprogesterone (17OHP), which is a mineralocorticoid (MC)-receptor antagonist. DESIGN: We investigated the renin-angiotensin-aldosterone system in patients with SW-CAH receiving twice daily modified-release hydrocortisone (MR-HC, Efmody) compared with standard glucocorticoid (GC) therapy. METHODS: Data were analyzed from the 6-month, phase 3 study of MR-HC (n = 42) versus standard GC therapy (n = 41). MC replacement therapy remained unchanged throughout the study. Blood pressure, serum potassium, serum sodium, plasma renin activity (PRA), and serum 17OHP and androstenedione concentrations were analyzed at baseline, 4, 12, and 24 weeks. RESULTS: The median serum 17OHP in the morning was significantly lower on MR-HC compared with standard GC at 24 weeks (2.5â
nmolâ
L-1 (IQR 8.3) versus 10.5â
nmolâ
L-1 (IQR 55.2), P = .001). PRA decreased significantly from baseline to 24 weeks in patients on MR-HC (0.83â
ngâ
L-1â
s-1 (IQR 1.0) to 0.48â
ngâ
L-1â
s-1 (IQR 0.61), P = .012) but not in patients on standard GC (0.53â
ngâ
L-1â
s-1 (IQR 0.66) to 0.52â
ngâ
L-1â
s-1 (IQR 0.78), P = .613). Serum sodium concentrations increased from baseline to 24 weeks in patients on MR-HC (138.8 ± 1.9â
mmolâ
L-1 to 139.3 ± 1.8â
mmolâ
L-1, P = .047), but remained unchanged on standard GC (139.8 ± 1.6â
mmolâ
L-1 to 139.3 ± 1.9â
mmolâ
L-1, P = .135). No significant changes were seen in systolic and diastolic blood pressure and serum potassium levels. CONCLUSION: 6 months of MR-HC therapy decreased PRA and increased sodium levels indicating a greater agonist action of the 9α-fluorocortisol dose, which may be due to the decreased levels of the MC-receptor antagonist 17OHP
Tolerance of triazineâresistant and susceptible biotypes of three weeds to heat stress: a fluorescence study
The photosynthetic performance of Solarium nigrum L. Poa annua L. and Chenopodium album L. resistant to triazines was investigated in order to determine whether the alteration of the 32âkD protein of photosystem (PS) II changed the ability to oxidize the PSII primary quinone acceptor QA. The effect of heat stress on the photochemistry of the resistant biotypes and the susceptible biotypes was also compared. The weeds were screened with the inâvivo modulated chlorophyll fluorescence device to measure the photochemical component of fluorescence quenching (qQ), which provided semiâquantitative information on the redox state of QA. At 25°C, an increase in the amplitude of the parameter 1âqQ, which reflected the reduced state of QA, was observed in all resistant biotypes, compared to the susceptible wild biotypes. This was attributable to a shift in the equilibrium between QAâ and QB (the PSII secondary quinone acceptor) in favour of QA. A heat stress of 35°C did not increase the level of reduced QA, except in the resistant biotypes of Poa annua. The photochemical activity of the two types of leaves exposed to increasingly high temperatures (25â65°C) indicated that quinone oxidation was more affected by heat stress in mutant resistant biotypes than in the susceptible biotypes. The quinone reoxidation was nullified at 60, 56 and 60°C, respectively, for susceptible biotypes of Solatium nigrum, Poa annua and Chenopodium album, and at 56, 48 and 54°C, respectively, for the three resistant biotypes. Heat also induced changes in the dark fluorescence F0, an indicator of the heat sensitivity of the lightâharvesting chlorophyll protein complex of PSII (LHCPII). The temperature dependence (25â70°C) of this fluorescence parameter confirmed the higher susceptibility of heatâtreated resistant leaves. Indeed, the temperatures of the peak of F0 (Tp) were 60, 55 and 62°C for susceptible Solanum nigrum, Poa annua and Chenopodium album, respectively. The Tp values for the three resistant biotypes were 55, 48 and 57°C, respectively. It is concluded that heat tolerance is related to differences in the organization of the chlorophyll antennae (LHCPII) between the two biotypes. Tolerance de biotypes sensibles et resistants aux triazines de 3 adventices au stress de la chaleur: une Ă©tude de fluorescence Les rendements photosynthĂ©tiques de Solanum nigrum L. Poa annua L. et Chenopodium album L. resistant aux triazines ont Ă©tĂ©Ă©tudiĂ©s en vue de dĂ©terminer dans quelle mesure l'altĂ©ration de la protĂ©ĂŻne 32 kD du photosystĂšme (PS) II, affecte la capacitĂ© d'oxyder l'accepteur quinonique primaire de PS II. QA L'influence d'un stress de chaleur sur la photochimie de biotypes rĂ©sistants et de biotypes sensibles a Ă©tĂ© comparĂ©e. Les mauvaises herbes ont Ă©tĂ© triĂ©es au moyen de la fluorescence de la chlorophylle in vivo, pour mesurer la composante photochimique de rĂ©duction de la fluorescence (qQ) qui donne une information semi quantitative de l'Ă©tat redox de QA. A 25 °C, une augmentation dans l'amplitude du paramĂštre 1âqQ, qui reflĂšte l'Ă©tat rĂ©duit de QA a Ă©tĂ© observĂ©e chez les biotypes resistants encomparaison des biotypes sauvages sensibles. Ceci a Ă©tĂ© attribuĂ©Ă une modification dans l'Ă©quilibre entre QâA et QB (l'accepteur quinonique secondaire PS II), en faveur de QA. Un stress thermique de 35°C n'a pas augmentĂ© le niveau de QA rĂ©duit, sauf chez le biotype rĂ©sistant de Poa annua. L'activitĂ© photochimique des feuilles des 2 types exposĂ©es Ă des hautes tempĂ©ratures croissantes (25 Ă 65°C) a montrĂ© que l'oxydation de la quinone Ă©tait plus affectĂ©e par le stress thermique chez les biotypes mutants rĂ©sistants que chez les biotypes sensibles. La rĂ©oxydation de la quinone Ă©tait annulĂ©e Ă 60, 56 et 60°C respectivement pour les biotypes sensibles de Solatium nigrum, Poa annua et Chenopodium album et Ă 56, 48 et 54°C respectivement pour les 3 biotypes rĂ©sistants. La chaleur a Ă©galement entrainĂ© des changements dans la fluorescence F0, un indicateur de la sensibilitĂ©Ă la chaleur du complexe collecteur de lumiĂšre du PS II (LHCP II). La dĂ©pendance avec la tempĂ©rature (25â70°C) de ce paramĂštre de fluorescence a confirmĂ© la plus grande sensibilitĂ© des feuilles rĂ©sistantes soumises Ă la chaleur. En effet, les tempĂ©ratures du pic de Fo (Tp) Ă©taient de 60, 55 et 62°C respectivement, pour les biotypes sensibles de Solanum nigrum, Poa annua et Chenopodium album. Les valeurs Tp pour les 3 biotypes rĂ©sistants Ă©taient respectivement de 55, 48 et 57°C. Il est conclu que la tolĂ©rance Ă la chaleur est liĂ©e aux diffĂ©rences dans l'organisation des antennes chlorophylliennes (LHC P II) entre les 2 biotypes. Hitzetoleranz Triazinâresistenter und âempfindlicher Biotypen von drei Unkrautarten Die photosynthetische Leistung Triazinâresistenter Biotypen von Solanum nigrum L. Poa annua L. und Chenopodium album L. wurde dahingehend untersucht, ob eine VerĂ€nderung des 32âkDâEiweisses des Pigmentsystems II (PII) die FĂ€higkeit Ă€nderte, den primĂ€ren QuinonâAkzeptor QA des PII zu oxidieren. Auch die Wirkung einer Hitzebehandlung auf die photochemischen Reaktionen resistenter und empfindlicher Biotypen wurde verglichen. Die UnkrĂ€uter wurden in vivo mit einem ChlorophyllâFluorimeter gescreent, um die photochemische Komponente der FluoreszenzâAuslösung (qQ) zu messen, die eine semiquantitative Information ĂŒber den RedoxâZustand des QA lieferte. Die Amplitude des Parameters lâqQ, der den reduzierten Zustand des QA widerspiegelte, nahm bei 25°C bei allen resistenten Biotypen im Vergleich zu den empfindlichen zu. Dies konnte einer Verschiebung des Gleichgewichts zwischen QâA und QB (dem sekundĂ€ren QuinonâAkzeptor QA des PII) zugunsten des QA zugeordnet werden. Eine Hitzebehandlung mit 35°C erhöhte den reduzierten QA nicht, auĂer bei resistenten Biotypen von Poa annua. Die photochemische AktivitĂ€t von BlĂ€ttern der beiden Typen, die steigenden Temperaturen von 25 bis 65°C unterworden wurden, zeigte, daĂ die QuinonâOxidation bei den resitenten Biotypen durch den HitzestreĂ stĂ€rker beeinfluĂt wurde als bei den empfindlichen. Die QuinonâReoxidation wurde bei den empfindlichen Biotypen von Solanum nigrum, Poa annua und Chenopodium album bei 60, 56 bzw. 60°C aufgehoben, bei den resistenten bei 56, 48 bzw. 54°C. Hitze fĂŒhrte auch zu Ănderungen der DunkelâFluoreszenz Fo, einem Indikator der Hitzeempfindlichkeit des lichtabsorbierenden ChlorophyllâEiweiĂkomplexes des PII (LHCPII). Die TemperaturabhĂ€ngigkeit dieses FluoreszenzâParameters bei 25 bis 70°C bestĂ€tigte die höhere Empfindlichkeit hitzebehandelter BlĂ€tter resistenter Pflanzen. So waren FoâPeaks bei empfindlichen Solanum nigrum, Poa annua und Chenopodium album bei 60, 55 bzw. 62°C, bei resistenten bei 55, 48 bzw. 57°C festzustellen. Daraus wurde geschlossen, daĂ die Hitzetoleranz auf Unterschieden im Aufbau des lichtabsorbierenden Pigmentsystems LHCPII der beiden Biotypen beruht. Copyright © 1992, Wiley Blackwell. All rights reservedSCOPUS: ar.jinfo:eu-repo/semantics/publishe