The Conical Point in the Ferroelectric Six-Vertex Model

We examine the last unexplored regime of the asymmetric six-vertex model: the low-temperature phase of the so-called ferroelectric model. The original publication of the exact solution, by Sutherland, Yang, and Yang, and various derivations and reviews published afterwards, do not contain many details about this regime. We study the exact solution for this model, by numerical and analytical methods. In particular, we examine the behavior of the model in the vicinity of an unusual coexistence point that we call the ``conical'' point. This point corresponds to additional singularities in the free energy that were not discussed in the original solution. We show analytically that in this point many polarizations coexist, and that unusual scaling properties hold in its vicinity.Comment: 28 pages (LaTeX); 8 postscript figures available on request ([email protected]). Submitted to Journal of Statistical Physics. SFU-DJBJDS-94-0

Effect of large magnetotactic bacteria with polyphosphate inclusions on the phosphate profile of the suboxic zone in the Black Sea

The Black Sea is the world’s largest anoxic basin and a model system for studying processes across redox gradients. In between the oxic surface and the deeper sulfidic waters there is an unusually broad layer of 10–40 m, where neither oxygen nor sulfide are detectable. In this suboxic zone, dissolved phosphate profiles display a pronounced minimum at the upper and a maximum at the lower boundary, with a peak of particulate phosphorus in between, which was suggested to be caused by the sorption of phosphate on sinking particles of metal oxides. Here we show that bacterial polyphosphate inclusions within large magnetotactic bacteria related to the genus Magnetococcus contribute substantially to the observed phosphorus peak, as they contain 26–34% phosphorus compared to only 1–5% in metal-rich particles. Furthermore, we found increased gene expression for polyphosphate kinases by several groups of bacteria including Magnetococcaceae at the phosphate maximum, indicating active bacterial polyphosphate degradation. We propose that large magnetotactic bacteria shuttle up and down within the suboxic zone, scavenging phosphate at the upper and releasing it at the lower boundary. In contrast to a passive transport via metal oxides, this bacterial transport can quantitatively explain the observed phosphate profiles.We are grateful for the competent technical assistance of Ronny Baaske, Christian Burmeister, Christin Laudan and Christian Meeske. We are greatly indebted to Cindy Lee and Bo Barker Jørgensen for providing extremely helpful comments on an earlier version of the manuscript. Horst D. Schulz and René Friedland are acknowledged for stimulating discussions on the modeling approach. We thank the captain and the crew of the R/V “Maria S. Merian” for the excellent support on board and the DFG (MSM33) and BMBF (01DK12043) for financing the cruise. The particle analysis was funded by the BMBF (03F0663A). S.B. was funded by a BONUS BLUEPRINT project (03F0679A awarded to KJ; http://blueprint- project.org), supported by BONUS (Art 185), funded jointly by the EU and the German Federal Ministry of Education and Research (BMBF). T. S. was funded by the German research foundation (DFG) (awarded to K.J., JU 367/16-1). Metagenome sequencing was done at the Swedish National Genomics Infrastructure (NGI) at SciLifeLab (Sweden).We are grateful for the competent technical assistance of Ronny Baaske, Christian Burmeister, Christin Laudan and Christian Meeske. We are greatly indebted to Cindy Lee and Bo Barker Jørgensen for providing extremely helpful comments on an earlier version of the manuscript. Horst D. Schulz and René Friedland are acknowledged for stimulating discussions on the modeling approach. We thank the captain and the crew of the R/V “Maria S. Merian” for the excellent support on board and the DFG (MSM33) and BMBF (01DK12043) for financing the cruise. The particle analysis was funded by the BMBF (03F0663A). S.B. was funded by a BONUS BLUEPRINT project (03F0679A awarded to KJ; http://blueprint- project.org), supported by BONUS (Art 185), funded jointly by the EU and the German Federal Ministry of Education and Research (BMBF). T. S. was funded by the German research foundation (DFG) (awarded to K.J., JU 367/16-1). Metagenome sequencing was done at the Swedish National Genomics Infrastructure (NGI) at SciLifeLab (Sweden)

Spatially heterogeneous ages in glassy dynamics

We construct a framework for the study of fluctuations in the nonequilibrium relaxation of glassy systems with and without quenched disorder. We study two types of two-time local correlators with the aim of characterizing the heterogeneous evolution: in one case we average the local correlators over histories of the thermal noise, in the other case we simply coarse-grain the local correlators. We explain why the former describe the fingerprint of quenched disorder when it exists, while the latter are linked to noise-induced mesoscopic fluctuations. We predict constraints on the pdfs of the fluctuations of the coarse-grained quantities. We show that locally defined correlations and responses are connected by a generalized local out-of-equilibrium fluctuation-dissipation relation. We argue that large-size heterogeneities in the age of the system survive in the long-time limit. The invariance of the theory under reparametrizations of time underlies these results. We relate the pdfs of local coarse-grained quantities and the theory of dynamic random manifolds. We define a two-time dependent correlation length from the spatial decay of the fluctuations in the two-time local functions. We present numerical tests performed on disordered spin models in finite and infinite dimensions. Finally, we explain how these ideas can be applied to the analysis of the dynamics of other glassy systems that can be either spin models without disorder or atomic and molecular glassy systems.Comment: 47 pages, 60 Fig

The TOP-SCOPE Survey of Planck Galactic Cold Clumps : Survey Overview and Results of an Exemplar Source, PGCC G26.53+0.17

The low dust temperatures (<14 K) of Planck Galactic cold clumps (PGCCs) make them ideal targets to probe the initial conditions and very early phase of star formation. "TOP-SCOPE" is a joint survey program targeting similar to 2000 PGCCs in J = 1-0 transitions of CO isotopologues and similar to 1000 PGCCs in 850 mu m continuum emission. The objective of the "TOP-SCOPE" survey and the joint surveys (SMT 10 m, KVN 21 m, and NRO 45 m) is to statistically study the initial conditions occurring during star formation and the evolution of molecular clouds, across a wide range of environments. The observations, data analysis, and example science cases for these surveys are introduced with an exemplar source, PGCC G26.53+0.17 (G26), which is a filamentary infrared dark cloud (IRDC). The total mass, length, and mean line mass (M/L) of the G26 filament are similar to 6200 M-circle dot, similar to 12 pc, and similar to 500 M-circle dot pc(-1), respectively. Ten massive clumps, including eight starless ones, are found along the filament. The most massive clump as a whole may still be in global collapse, while its denser part seems to be undergoing expansion owing to outflow feedback. The fragmentation in the G26 filament from cloud scale to clump scale is in agreement with gravitational fragmentation of an isothermal, nonmagnetized, and turbulent supported cylinder. A bimodal behavior in dust emissivity spectral index (beta) distribution is found in G26, suggesting grain growth along the filament. The G26 filament may be formed owing to large-scale compression flows evidenced by the temperature and velocity gradients across its natal cloud.Peer reviewe

Examining the generalizability of research findings from archival data

This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability—for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe

The Open Anchoring Quest Dataset: Anchored Estimates from 96 Studies on Anchoring Effects

People’s estimates are biased toward previously considered numbers (anchoring). We have aggregated all available data from anchoring studies that included at least two anchors into one large dataset. Data were standardized to comprise one estimate per row, coded according to a wide range of variables, and are available for download and analyses online (https://metaanalyses.shinyapps.io/OpAQ/). Because the dataset includes both original and meta-data it allows for fine-grained analyses (e.g., correlations of estimates for different tasks) but also for meta-analyses (e.g., effect sizes for anchoring effects)