Infinite-randomness critical point in the two-dimensional disordered contact process

We study the nonequilibrium phase transition in the two-dimensional contact process on a randomly diluted lattice by means of large-scale Monte-Carlo simulations for times up to $10^{10}$ and system sizes up to $8000 \times 8000$ sites. Our data provide strong evidence for the transition being controlled by an exotic infinite-randomness critical point with activated (exponential) dynamical scaling. We calculate the critical exponents of the transition and find them to be universal, i.e., independent of disorder strength. The Griffiths region between the clean and the dirty critical points exhibits power-law dynamical scaling with continuously varying exponents. We discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder. Our results are of importance beyond absorbing state transitions because according to a strong-disorder renormalization group analysis, our transition belongs to the universality class of the two-dimensional random transverse-field Ising model.Comment: 13 pages, 12 eps figures, final version as publishe

Trajectory and stability of Lagrangian point L2L_2 in the Sun-Earth system

This paper describes design of the trajectory and analysis of the stability of collinear point $L_2$ in the Sun-Earth system. The modified restricted three body problem with additional gravitational potential from the belt is used as the model for the Sun-Earth system. The effect of radiation pressure of the Sun and oblate shape of the Earth are considered. The point $L_2$ is asymptotically stable upto a specific value of time $t$ correspond to each set of values of parameters and initial conditions. The results obtained from this study would be applicable to locate a satellite, a telescope or a space station around the point $L_2$.Comment: Accepted for publication in Astrophysics & Space Scienc

Rare sulfur and triple oxygen isotope geochemistry of volcanogenic sulfate aerosols

We present analyses of stable isotopic ratios ^(17)O/^(16)O, ^(18)O/^(16)O, ^(34)S/^(32)S, and ^(33)S/^(32)S, ^(36)S/^(32)S in sulfate leached from volcanic ash of a series of well known, large and small volcanic eruptions. We consider eruptions of Mt. St. Helens (Washington, 1980, ∼1 km^3), Mt. Spurr (Alaska, 1953, <1 km3), Gjalp (Iceland, 1996, 1998, <1 km^3), Pinatubo (Phillipines, 1991, 10 km^3), Bishop tuff (Long Valley, California, 0.76 Ma, 750 km^3), Lower Bandelier tuff (Toledo Caldera, New Mexico, 1.61 Ma, 600 km^3), and Lava Creek and Huckleberry Ridge tuffs (Yellowstone, Wyoming, 0.64 Ma, 1000 km^3 and 2.04 Ma 2500 km^3, respectively). This list covers much of the diversity of sizes and the character of silicic volcanic eruptions. Particular emphasis is paid to the Lava Creek tuff for which we present wide geographic sample coverage. This global dataset spans a significant range in δ^(34)S, δ^(18)O, and Δ^(17)O of sulfate (29‰, 30‰, and 3.3‰, respectively) with oxygen isotopes recording mass-independent (Δ^(17)O > 0.2‰) and sulfur isotopes exhibiting mass-dependent behavior. Products of large eruptions account for most of‘ these isotopic ranges. Sulfate with Δ^(17)O > 0.2‰ is present as 1–10 μm gypsum crystals on distal ash particles and records the isotopic signature of stratospheric photochemical reactions. Sediments that embed ash layers do not contain sulfate or contain little sulfate with Δ^(17)O near 0‰, suggesting that the observed sulfate in ash is of volcanic origin. Mass-dependent fractionation of sulfur isotopic ratios suggests that sulfate-forming reactions did not involve photolysis of SO2, like that inferred for pre-2.3 Ga sulfates from Archean sediments or Antarctic ice-core sulfate associated with few dated eruptions. Even though the sulfate sulfur isotopic compositions reflect mass-dependent processes, the products of caldera-forming eruptions display a large δ^(34)S range and exhibit fractionation relationships that do not follow the expected equilibrium slopes of 0.515 and 1.90 for ^(33)S/^(32)S vs. ^(34)S/^(32)S and ^(36)S/^(32)S vs. ^(34)S/^(32)S, respectively. The data presented here are consistent with modification of a chemical mass-dependent fractionation of sulfur isotopes in the volcanic plume by either a kinetic gas phase reaction of volcanic SO_2 with OH and/or a Rayleigh processes involving a residual Rayleigh reactant—volcanic SO_2 gas, rather than a Rayleigh product. These results may also imply at least two removal pathways for SO_2 in volcanic plumes. Above-zero Δ^(17)O values and their positive correlation with δ^(18)O in sulfate can be explained by oxidation by high-δ^(18)O and high-Δ^(17)O compounds such as ozone and radicals such as OH that result from ozone break down. Large caldera-forming eruptions have the highest Δ^(17)O values, and the largest range of δ^(18)O, which can be explained by stratospheric reaction with ozone-derived OH radicals. These results suggest that massive eruptions are capable of causing a temporary depletion of the ozone layer. Such depletion may be many times that of the measured 3–8% depletion following 1991 Pinatubo eruption, if the amount of sulfur dioxide released scales with the amount of ozone depletion

Legumes are different:Leaf nitrogen, photosynthesis, and water use efficiency

Using robust, pairwise comparisons and a global dataset, we show that nitrogen concentration per unit leaf mass for nitrogen-fixing plants (N(2)FP; mainly legumes plus some actinorhizal species) in nonagricultural ecosystems is universally greater (43–100%) than that for other plants (OP). This difference is maintained across Koppen climate zones and growth forms and strongest in the wet tropics and within deciduous angiosperms. N(2)FP mostly show a similar advantage over OP in nitrogen per leaf area (N(area)), even in arid climates, despite diazotrophy being sensitive to drought. We also show that, for most N(2)FP, carbon fixation by photosynthesis (A(sat)) and stomatal conductance (g(s)) are not related to N(area)—in distinct challenge to current theories that place the leaf nitrogen–A(sat) relationship at the center of explanations of plant fitness and competitive ability. Among N(2)FP, only forbs displayed an N(area)–g(s) relationship similar to that for OP, whereas intrinsic water use efficiency (WUE(i); A(sat)/g(s)) was positively related to N(area) for woody N(2)FP. Enhanced foliar nitrogen (relative to OP) contributes strongly to other evolutionarily advantageous attributes of legumes, such as seed nitrogen and herbivore defense. These alternate explanations of clear differences in leaf N between N(2)FP and OP have significant implications (e.g., for global models of carbon fluxes based on relationships between leaf N and A(sat)). Combined, greater WUE and leaf nitrogen—in a variety of forms—enhance fitness and survival of genomes of N(2)FP, particularly in arid and semiarid climates

Effectiveness of social egg freezing: Protocol for systematic review and meta-analyses

© 2019 Author(s). Introduction Social egg freezing is storing egg for the purpose of preserving fertility and delayed childbearing. Currently, little is known about the utilisation and effectiveness of this approach. This review aims to determine (1) the proportion of women who used their stored eggs, and (2) the egg survival rate through vitrification, and the clinical pregnancy rate and live birth rate per 100 women partaking in the procedure, and among women who stored their eggs for medical reasons. Methods and analyses This systematic review will be done according to the items listed in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. PubMed, Embase, Scopus, The Cumulative Index to Nursing and Allied Health Literature (CINAHL) and the Cochrane Library and Health Technology Assessment databases will be searched to identify eligible studies published since 2012. Two reviewers will independently appraise the eligibility and quality of the studies based on preset checklists and extract the data using a data extraction template. Outcomes of interest are proportion of women who used their stored eggs, egg survival rate, pregnancy rate and live birth rates. We will determine the presence heterogeneity among studies using the Cochrane's Q test. The percentage of total variation across studies, which is due to statistical heterogeneity, will be calculated using the I 2 statistics. Outcomes of interest will be pooled together using metaprop programme STATA V.14. Ethics and dissemination For this review, ethical committee approval is not required. We will use publically available data from previously published studies. The final report of the review will be disseminated through publication on national or international journal, and it will be presented on different scientific conferences

Foundation of Statistical Mechanics under experimentally realistic conditions

We demonstrate the equilibration of isolated macroscopic quantum systems, prepared in non-equilibrium mixed states with significant population of many energy levels, and observed by instruments with a reasonably bound working range compared to the resolution limit. Both properties are fulfilled under many, if not all, experimentally realistic conditions. At equilibrium, the predictions and limitations of Statistical Mechanics are recovered.Comment: Accepted in Phys. Rev. Let

Mercury Orbiter: Report of the Science Working Team

The results are presented of the Mercury Orbiter Science Working Team which held three workshops in 1988 to 1989 under the auspices of the Space Physics and Planetary Exploration Divisions of NASA Headquarters. Spacecraft engineering and mission design studies at the Jet Propulsion Lab were conducted in parallel with this effort and are detailed elsewhere. The findings of the engineering study, summarized herein, indicate that spin stabilized spacecraft carrying comprehensive particles and fields experiments and key planetology instruments in high elliptical orbits can survive and function in Mercury orbit without costly sun shields and active cooling systems

Large sulfur isotope fractionations in Martian sediments at Gale crater

Variability in the sulfur isotopic composition in sediments can reflect atmospheric, geologic and biological processes. Evidence for ancient fluvio-lacustrine environments at Gale crater on Mars and a lack of efficient crustal recycling mechanisms on the planet suggests a surface environment that was once warm enough to allow the presence of liquid water, at least for discrete periods of time, and implies a greenhouse effect that may have been influenced by sulfur-bearing volcanic gases. Here we report in situ analyses of the sulfur isotopic compositions of SO2 volatilized from ten sediment samples acquired by NASA’s Curiosity rover along a 13 km traverse of Gale crater. We find large variations in sulfur isotopic composition that exceed those measured for Martian meteorites and show both depletion and enrichment in 34S. Measured values of δ34S range from −47 ± 14‰ to 28 ± 7‰, similar to the range typical of terrestrial environments. Although limited geochronological constraints on the stratigraphy traversed by Curiosity are available, we propose that the observed sulfur isotopic signatures at Gale crater can be explained by equilibrium fractionation between sulfate and sulfide in an impact-driven hydrothermal system and atmospheric processing of sulfur-bearing gases during transient warm periods

Canonical thermalization

For quantum systems that are weakly coupled to a much 'bigger' environment, thermalization of possibly far from equilibrium initial ensembles is demonstrated: for sufficiently large times, the ensemble is for all practical purposes indistinguishable from a canonical density operator under conditions that are satisfied under many, if not all, experimentally realistic conditions