Ambiguous Dependence Of Minimal Plant Generation Time On Nuclear DNA Content

AMBIGUOUS DEPENDENCE OF MINIMAL PLANT GENERATION TIME ON NUCLEAR DNA CONTENT Victor B. Ivanov The minimum generation time (MGT) of plant development was suggested to depend on nuclear DNA content, which varies in plants over wide limits1. In ephemeral species with the shortest MGT, the average C values were significantly lower than in annual species, whereas the average C values in annual species were lower than those in perennial plants. However, nobody has paid attention to the ratio of annual to perennial species number as a function of C values. Here I show that with increasing C the ratio of annual to perennial species increases to C values equal to 7-8 pg (monocots) and 6-7 pg (eudicots) and then decreases and that the fraction of annuals is abundant not at the lowest, but at some higher C levels. Hence, C value increase exerts an ambiguous effect on MGT. The C value is not the only factor, which determines the duration of the plant development. Nevertheless, the nuclear DNA content exerts a pronounced effect on MGT together with other diverse factors affecting the rate of plant development, especially at higher C values

Coronary heart disease risks associated with high levels of HDL cholesterol.

BackgroundThe association between high-density lipoprotein cholesterol (HDL-C) and coronary heart disease (CHD) events is not well described in individuals with very high levels of HDL-C (>80 mg/dL).Methods and resultsUsing pooled data from 6 community-based cohorts we examined CHD and total mortality risks across a broad range of HDL-C, including values in excess of 80 mg/dL. We used Cox proportional hazards models with penalized splines to assess multivariable, adjusted, sex-stratified associations of HDL-C with the hazard for CHD events and total mortality, using HDL-C 45 mg/dL and 55 mg/dL as the referent in men and women, respectively. Analyses included 11 515 men and 12 925 women yielding 307 245 person-years of follow-up. In men, the association between HDL-C and CHD events was inverse and linear across most HDL-C values; however at HDL-C values >90 mg/dL there was a plateau effect in the pattern of association. In women, the association between HDL-C and CHD events was inverse and linear across lower values of HDL-C, however at HDL-C values >75 mg/dL there were no further reductions in the hazard ratio point estimates for CHD. In unadjusted models there were increased total mortality risks in men with very high HDL-C, however mortality risks observed in participants with very high HDL-C were attenuated after adjustment for traditional risk factors.ConclusionsWe did not observe further reductions in CHD risk with HDL-C values higher than 90 mg/dL in men and 75 mg/dL in women

Living \u3cem\u3eMore Than\u3c/em\u3e Just Enough for the City: Persistence of High-Quality Vegetation in Natural Areas in an Urban Setting

Urban environments pose special challenges to flora, including altered disturbance regimes, habitat fragmentation, and increased opportunity for invasion by non-native species. In addition, urban natural area represents most people’s contact with nature, given the majority of the world’s population currently live in cities. We used coefficients of conservatism (C-values), a system that ranks species based on perceived fidelity to remnant native plant communities that retain ecological integrity, to quantify habitat quality of 14 sites covering 850 ha within the city of Indianapolis, Indiana, in the Midwestern United States. All sites contained significant natural area and were inventoried via intensive complete censuses throughout one or two growing seasons within the last 15 years. Mean C-values for five sites were high, especially when compared to values reported for the highest quality preserves in central Indiana. However, for most sites the difference in mean C-value with and without non-natives was rather high, meaning that natural quality is likely to have been compromised by the presence of non-natives. Sites receiving the highest levels of stewardship and those with the least public access via trails had the highest mean native C-values. A total of 34 invasive non-native species were found across all 14 sites. Most were woody species. Mean C-value over all sites was significantly negatively correlated with the number of non-natives present, especially those considered invasive. These results demonstrate for the Indianapolis area, and likely other urbanized Midwestern cities, remnant natural areas can retain high ecological value, especially if they receive regular environmental stewardship

A very low resistance, non-sintered contact system for use on indium phosphide concentrator/shallow junction solar cells

An investigation is made into the possibility of providing low resistance contacts to shallow junction InP solar cells which do not require sintering and which do not cause device degradation even when subjected to extended annealing at elevated temperatures. We show that the addition of In to Au contacts in amounts that exceed the solid solubility limit lowers the as-fabricated (unsintered) contact resistivity (R sub c) to the 10(exp -5) ohm cm(exp 2) range. We next consider the contact system Au/Au2P3, which has been shown to exhibit as-fabricated R sub c values in the 10(exp -6) ohm cm(exp 2) range, but which fails quickly when heated. We show that the substitution of a refractory metal (W, Ta) for Au preserves the low R sub c values while preventing the destructive reactions that would normally take place in this system at high temperatures. We show, finally, that R sub c values in the 10(exp -7) ohm cm(exp 2) range can be achieved without sintering by combining the effects of In or Ga additions to Au contacts with the effects of introducing a thin Au2P3 layer at the metal-InP interface

On Conformal Field Theories With Extremal a/c Values

Unitary conformal field theories (CFTs) are believed to have positive (non-negative) energy correlators. Energy correlators are universal observables in higher-dimensional CFTs built out of integrated Wightman functions of the stress-energy tensor. We analyze energy correlators in parity invariant four-dimensional CFTs. The goal is to use the positivity of energy correlators to further constrain unitary CFTs. It is known that the positivity of the simplest one-point energy correlator implies that 1/3 <= a/c <= 31/18 where a and c are the Weyl anomaly coefficients. We use the positivity of higher point energy correlators to show that CFTs with extremal values of a/c have trivial scattering observables. More precisely, for a/c=1/3 and a/c=31/18 all energy correlators are fixed to be the ones of the free boson and the free vector theory correspondingly. Similarly, we show that the positivity and finiteness of energy correlators together imply that the three-point function of the stress tensor in a CFT cannot be proportional to the one in the theory of free boson, free fermion or free vector field.Comment: 24 pages, 3 figure

Transport and magnetic properties of Co-doped BaFe_{2}As_{2} epitaxial thin films

We report resistivity, Hall coefficient, current-voltage characteristics, and magneto-optical imaging measurements of epitaxial Co-doped BaFe_{2}As_{2} thin films deposited on MgO(001) substrate. The Hall resistivity of the films has a substantial contribution arising from anomalous Hall effect of ferromagnetic components. The critical current density (J_{c}) of the films is ~2 MA/cm^{2} at low temperatures. Differential magneto-optical images of the remanent state give similar J_{c} values and also exhibit presence of extended defects in the film.Comment: 9 pages, 4 figure

Period and light curve fluctuations of the Kepler Cepheid V1154 Cyg

We present a detailed period analysis of the bright Cepheid-type variable star V1154 Cygni (V =9.1 mag, P~4.9 d) based on almost 600 days of continuous observations by the Kepler space telescope. The data reveal significant cycle-to-cycle fluctuations in the pulsation period, indicating that classical Cepheids may not be as accurate astrophysical clocks as commonly believed: regardless of the specific points used to determine the O-C values, the cycle lengths show a scatter of 0.015-0.02 days over the 120 cycles covered by the observations. A very slight correlation between the individual Fourier parameters and the O-C values was found, suggesting that the O - C variations might be due to the instability of the light curve shape. Random fluctuation tests revealed a linear trend up to a cycle difference 15, but for long term, the period remains around the mean value. We compare the measurements with simulated light curves that were constructed to mimic V1154 Cyg as a perfect pulsator modulated only by the light travel time effect caused by low-mass companions. We show that the observed period jitter in V1154 Cyg represents a serious limitation in the search for binary companions. While the Kepler data are accurate enough to allow the detection of planetary bodies in close orbits around a Cepheid, the astrophysical noise can easily hide the signal of the light-time effect.Comment: published in MNRAS: 8 pages, 7 figure