Taylor's law and related allometric power laws in New Zealand mountain beech forests: the roles of space, time and environment

This is the author accepted manuscript. The final version is available from Wiley via https://doi.org/10.1111/oik.02622Taylor's law says that the variance of population density of a species is proportional to a power of mean population density. Density–mass allometry says that mean population density is proportional to a power of mean biomass per individual. These power laws predict a third, variance–mass allometry: the variance of population density of a species is proportional to a power of mean biomass per individual. We tested these laws using 10 censuses of New Zealand mountain beech trees in 250 plots over 30 years at spatial scales from 5 m to kilometers. We found that: 1) a single-species forest not disrupted by humans obeyed all three laws; 2) random sampling explained the parameters of Taylor's law at a large spatial scale in 8 of 10 censuses, but not at a fine spatial scale; 3) larger spatial scale increased the exponent of Taylor's law and decreased the exponent of variance–mass allometry (this is the first empirical demonstration that the latter exponent depends on spatial scale), but affected the exponent of density–mass allometry slightly; 4) despite varying natural disturbance, the three laws varied relatively little over the 30 years; 5) self-thinning and recruiting plots had significantly different intercepts and slopes of density–mass allometry and variance–mass allometry, but the parameters of Taylor's law were not usually significantly affected; and 6) higher soil calcium was associated with higher variance of population density in all censuses but not with a difference in the exponent of Taylor's law, while elevation above sea level and soil carbon-to-nitrogen ratios had little effect on the parameters of Taylor's law. In general, the three laws were remarkably robust. When their parameters were influenced by spatial scale and environmental factors, the parameters could not be species-specific indicators. We suggest biological mechanisms that may explain some of these findings.JEC acknowledges U.S. National Science Foundation grant DMS-1225529 and the assistance of Priscilla K. Rogerson. RBA was supported by Landcare Research. This project benefited from many years of input by staff of the former New Zealand Forest Service, Forest and Range Experiment Station, Forest Research Institute and currently Landcare Research

Photodissociation and the Morphology of HI in Galaxies

Young massive stars produce Far-UV photons which dissociate the molecular gas on the surfaces of their parent molecular clouds. Of the many dissociation products which result from this ``back-reaction'', atomic hydrogen \HI is one of the easiest to observe through its radio 21-cm hyperfine line emission. In this paper I first review the physics of this process and describe a simplified model which has been developed to permit an approximate computation of the column density of photodissociated \HI which appears on the surfaces of molecular clouds. I then review several features of the \HI morphology of galaxies on a variety of length scales and describe how photodissociation might account for some of these observations. Finally, I discuss several consequences which follow if this view of the origin of HI in galaxies continues to be successful.Comment: 18 pages, 7 figures in 8 files, invited review paper for the conference "Penetrating Bars Through Masks of Cosmic Dust: The Hubble Tuning Fork Strikes a New Note", South Africa, June 2004. Proceedings to be published by Kluwer, eds. D.L. Block, K.C. Freeman, I. Puerari, R. Groess, & E.K. Bloc

The Effect Of Cytochalasin B Dosage On The Survival And Ploidy Of Crassostrea Virginica (Gmelin) Larvae

Survival and ploidy of D-stage oyster larvae (Crassostrea virginica) were determined following the rearing of embryos exposed to CB dosages of 0.5 mg/L, 0.25 mg/L, and 0.125 mg/L for 10 minutes, with 0.05% DMSO and ambient seawater as controls. The experiment was replicated three times on the same day with the same procedures and partially stripping the same male oysters; different females were used for each replicate. CB dosage treatments began when 50% of the eggs reached PBI (24-31 min). Embryos were reared for 48 h at ambient temperature and salinity. Resulting triploid percentages were 13% +/- 6.7% (0.125 mgCB/L), 61.8% +/- 6.2% (0.75 mgCB/L). and 68.2% +/- 14.1% (0.5 mgCB/L). No significant difference (P less than or equal to 0.05) in mean survival was found between the three CB treatments. Significant differences in mean survival between the three replicates implies variability because of different sources of eggs

The role of mentorship in protege performance

The role of mentorship on protege performance is a matter of importance to academic, business, and governmental organizations. While the benefits of mentorship for proteges, mentors and their organizations are apparent, the extent to which proteges mimic their mentors' career choices and acquire their mentorship skills is unclear. Here, we investigate one aspect of mentor emulation by studying mentorship fecundity---the number of proteges a mentor trains---with data from the Mathematics Genealogy Project, which tracks the mentorship record of thousands of mathematicians over several centuries. We demonstrate that fecundity among academic mathematicians is correlated with other measures of academic success. We also find that the average fecundity of mentors remains stable over 60 years of recorded mentorship. We further uncover three significant correlations in mentorship fecundity. First, mentors with small mentorship fecundity train proteges that go on to have a 37% larger than expected mentorship fecundity. Second, in the first third of their career, mentors with large fecundity train proteges that go on to have a 29% larger than expected fecundity. Finally, in the last third of their career, mentors with large fecundity train proteges that go on to have a 31% smaller than expected fecundity.Comment: 23 pages double-spaced, 4 figure

SSR markers reveal diversity in Guinea yam (Dioscorea cayenensis/D. rotundata) core set

The genetic diversity of 219 accessions of Guinea yam germplasm from Benin, Congo, Côte d’ Ivoire, Equatorial Guinea, Gabon, Ghana, Nigeria, Sierra Leone and Togo was accessed using 15 microsatelliteloci. High diversity of 0.677 was found among the accessions. An allelic average of 8.06 and polymorphic information content (PIC) value of 0.65 was observed for the markers. The observed heterozygosity value of 0.563 suggests that spontaneous hybridization must have contributed to the ancestry of some of the accessions and improvement by farmers must have been far more often by selection of somatic mutants. The twenty distinct cluster groups generated by the radial phylogram shows that Dioscorea cayenensis and D. rotundata are distinct species with intermediate hybrid forms. There was no relationship between relatedness of the accessions and their geographical area of origin. This study contributes to an increased understanding of the genetic organisation of the coregermplasm

Whither Capitalism? Financial externalities and crisis

As with global warming, so with financial crises – externalities have a lot to answer for. We look at three of them. First the financial accelerator due to ‘fire sales’ of collateral assets -- a form of pecuniary externality that leads to liquidity being undervalued. Second the ‘risk- shifting’ behaviour of highly-levered financial institutions who keep the upside of risky investment while passing the downside to others thanks to limited liability. Finally, the network externality where the structure of the financial industry helps propagate shocks around the system unless this is checked by some form of circuit breaker, or ‘ring-fence’. The contrast between crisis-induced Great Recession and its aftermath of slow growth in the West and the rapid - and (so far) sustained - growth in the East suggests that successful economic progress may depend on how well these externalities are managed

Ion Write Microthermotics: Programing Thermal Metamaterials at the Microscale.

Considerable advances in manipulating heat flow in solids have been made through the innovation of artificial thermal structures such as thermal diodes, camouflages, and cloaks. Such thermal devices can be readily constructed only at the macroscale by mechanically assembling different materials with distinct values of thermal conductivity. Here, we extend these concepts to the microscale by demonstrating a monolithic material structure on which nearly arbitrary microscale thermal metamaterial patterns can be written and programmed. It is based on a single, suspended silicon membrane whose thermal conductivity is locally, continuously, and reversibly engineered over a wide range (between 2 and 65 W/m·K) and with fine spatial resolution (10-100 nm) by focused ion irradiation. Our thermal cloak demonstration shows how ion-write microthermotics can be used as a lithography-free platform to create thermal metamaterials that control heat flow at the microscale

Electrohydrodynamic stability of a plasma-liquid interface

Many plasma applications involve the plasma coming into contact with a liquid surface. Previous analyses of the stability of such liquid surfaces have neglected the presence of the sheath region between the bulk plasma and the liquid. Large electric fields, typically in excess of several MV m−1, and strong ion flows are present in this region. This paper considers a linear perturbation analysis of a liquid-sheath interface in order to find the marginal condition for instability. This condition shows that molten metal surfaces in tokamak edge plasmas are stable against the electric field, if a normal sheath is formed, due to the impact of ions on the surface. The stabilization of the liquid surface by ion bombardment is encouraging for the ongoing development of plasma-liquid technologies