Metal-rich stars are less suitable for the evolution of life on their planets.

Atmospheric ozone and oxygen protect the terrestrial biosphere against harmful ultraviolet (UV) radiation. Here, we model atmospheres of Earth-like planets hosted by stars with near-solar effective temperatures (5300 to 6300 K) and a broad range of metallicities covering known exoplanet host stars. We show that paradoxically, although metal-rich stars emit substantially less ultraviolet radiation than metal-poor stars, the surface of their planets is exposed to more intense ultraviolet radiation. For the stellar types considered, metallicity has a larger impact than stellar temperature. During the evolution of the universe, newly formed stars have progressively become more metal-rich, exposing organisms to increasingly intense ultraviolet radiation. Our findings imply that planets hosted by stars with low metallicity are the best targets to search for complex life on land.

THE THERMOLUMINESCENCE (TL) DOSE RESPONSE OF COMPOSITE PEAK 5 IN LIF:MG,TI (TLD-100): DEPENDENCE ON THE ORDER OF KINETICS.

A seeming contradiction in the prediction of the spatially correlated trapping center/luminescent center model applied to LiF:Mg,Ti has been the linear/supralinear behavior of the dose response of glow peak 5a. In the TC/LC model, the localised electron-hole recombination, giving rise to glow peak 5a, is expected to result in an extended region of linear dose response. Deconvolution of the glow curves based on first order kinetic peak shapes results, however, in a dose response of peak 5a, which closely resembles the linear/supralinear dose response of peak 5. It is demonstrated herein that when general-order kinetics peak shapes are used for peak 5a, the analysis can result in a linear dose response of glow peak 5a up to dose levels as high as 30 Gy, well beyond the 1-Gy onset of supralinearity of peak 5. The extended linearity suggests a resolution of the contradiction.

Kinetics of Calcite Dissolution and Ca-Mg Ion Exchange on the Surfaces of North Sea Chalk Powders.

Calcite dissolution and Ca-Mg ion exchange on carbonate rock surfaces have been proposed as potential mechanisms occurring during smart waterflooding in carbonate reservoirs. However, there is still a lack of fundamental understanding of these reactions to quantitatively evaluate their effects in the reservoir flooding process. Especially, the data on precipitation and dissolution kinetics are insufficient. In this work, the equilibration kinetics of calcite dissolution and Ca-Mg exchange was experimentally studied. The behavior of three powders was compared: pure calcium carbonate, Stevns Klint outcrop chalk, and North Sea reservoir chalk. It was found that the equilibration time for calcite dissolution was of the order of seconds for a given surface-area-to-liquid-volume ratio. The existing theory of calcite dissolution could well reproduce our observations. The Ca-Mg exchange showed two-step kinetics: the first step was fast, and it dominated the process within the first hour of reaction; the second step was slow, and it continued longer than the time of observation (2 weeks). Characteristic times for the two steps were extracted by fitting the experimental curves. A two-layer adsorption model was proposed to characterize the kinetic process and successfully matched with experimental data. The findings were further extended to flow-through scenarios. By comparing with literature data and surface complexation models, it was concluded that calcite dissolution alone was unlikely to be able to explain the additional recovery reported in the literature. The Ca-Mg exchange process could dominate the fluid-rock interactions at a high temperature in pure calcium carbonate rocks, while competitive adsorption of cations appeared to control the process at a lower temperature. Different carbonate rocks possess different properties with regard to the ion-exchange process.

The Sun is less active than other solar-like stars.

The magnetic activity of the Sun and other stars causes their brightness to vary. We investigated how typical the Sun's variability is compared with other solar-like stars, i.e., those with near-solar effective temperatures and rotation periods. By combining 4 years of photometric observations from the Kepler space telescope with astrometric data from the Gaia spacecraft, we were able to measure photometric variabilities of 369 solar-like stars. Most of those with well-determined rotation periods showed higher variability than the Sun and are therefore considerably more active. These stars appear nearly identical to the Sun except for their higher variability. Therefore, we speculate that the Sun could potentially also go through epochs of such high variability.

Flavivirus Nonstructural Protein NS5 Dysregulates HSP90 to Broadly Inhibit JAK/STAT Signaling.

Pathogenic flaviviruses antagonize host cell Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling downstream of interferons α/ß. Here, we show that flaviviruses inhibit JAK/STAT signaling induced by a wide range of cytokines beyond interferon, including interleukins. This broad inhibition was mapped to viral nonstructural protein 5 (NS5) binding to cellular heat shock protein 90 (HSP90), resulting in reduced Janus kinase-HSP90 interaction and thus destabilization of unchaperoned JAKs (and other kinase clients) of HSP90 during infection by Zika virus, West Nile virus, and Japanese encephalitis virus. Our studies implicate viral dysregulation of HSP90 and the JAK/STAT pathway as a critical determinant of cytokine signaling control during flavivirus infection.

Modified Distribution-Free Goodness-of-Fit Test Statistic.

Covariance structure analysis and its structural equation modeling extensions have become one of the most widely used methodologies in social sciences such as psychology, education, and economics. An important issue in such analysis is to assess the goodness of fit of a model under analysis. One of the most popular test statistics used in covariance structure analysis is the asymptotically distribution-free (ADF) test statistic introduced by Browne (Br J Math Stat Psychol 37:62-83, 1984). The ADF statistic can be used to test models without any specific distribution assumption (e.g., multivariate normal distribution) of the observed data. Despite its advantage, it has been shown in various empirical studies that unless sample sizes are extremely large, this ADF statistic could perform very poorly in practice. In this paper, we provide a theoretical explanation for this phenomenon and further propose a modified test statistic that improves the performance in samples of realistic size. The proposed statistic deals with the possible ill-conditioning of the involved large-scale covariance matrices.

Comment on the asymptotics of a distribution-free goodness of fit test statistic.

In a recent article Jennrich and Satorra (Psychometrika 78: 545-552, 2013) showed that a proof by Browne (British Journal of Mathematical and Statistical Psychology 37: 62-83, 1984) of the asymptotic distribution of a goodness of fit test statistic is incomplete because it fails to prove that the orthogonal component function employed is continuous. Jennrich and Satorra (Psychometrika 78: 545-552, 2013) showed how Browne's proof can be completed satisfactorily but this required the development of an extensive and mathematically sophisticated framework for continuous orthogonal component functions. This short note provides a simple proof of the asymptotic distribution of Browne's (British Journal of Mathematical and Statistical Psychology 37: 62-83, 1984) test statistic by using an equivalent form of the statistic that does not involve orthogonal component functions and consequently avoids all complicating issues associated with them.

Automated long-term tracking and social behavioural phenotyping of animal colonies within a semi-natural environment.

Social behaviour has a key role in animal survival across species, ranging from insects to primates and humans. However, the biological mechanisms driving natural interactions between multiple animals, over long-term periods, are poorly studied and remain elusive. Rigorous and objective quantification of behavioural parameters within a group poses a major challenge as it requires simultaneous monitoring of the positions of several individuals and comprehensive consideration of many complex factors. Automatic tracking and phenotyping of interacting animals could thus overcome the limitations of manual tracking methods. Here we report a broadly applicable system that automatically tracks the locations of multiple, uniquely identified animals, such as mice, within a semi-natural setting. The system combines video and radio frequency identified tracking data to obtain detailed behavioural profiles of both individuals and groups. We demonstrate the usefulness of these data in characterizing individual phenotypes, interactions between pairs and the collective social organization of groups.

A theoretical analysis of colloid attachment and straining in chemically heterogeneous porous media.

A balance of applied hydrodynamic (T(H)) and resisting adhesive (T(A)) torques was conducted over a chemically heterogeneous porous medium that contained random roughness of height h(r) to determine the fraction of the solid surface area that contributes to colloid immobilization (S(f)*) under unfavorable attachment conditions. This model considers resistance due to deformation and the horizontal component of the adhesive force (F(AT)), spatial variations in the pore scale velocity distribution, and the influence of hr on lever arms for T(H) and T(A). Values of S(f)* were calculated for a wide range of physicochemical properties to gain insight into mechanisms and factors influencing colloid immobilization. Colloid attachment processes were demonstrated to depend on solution ionic strength (IS), the colloid radius (r(c)), the Young's modulus (K), the amount of chemical heterogeneity (P+), and the Darcy velocity (q). Colloid immobilization was also demonstrated to occur on a rough surface in the absence of attachment. In this case, S(f)* depended on IS, r(c), the roughness fraction (f0), h(r), and q. Roughness tended to enhance T(A) and diminish T(H). Consequently, the effect of IS on S(f)* was enhanced by h(r) relative to attachment. In contrast, the effects of r(c) and q on S(f)* were diminished by hr in comparison to attachment. Colloid immobilization adjacent to macroscopic roughness locations shares many similarities to grain-grain contact points and may be viewed as a type of straining process. In general, attachment was more important for higher IS and variance in the secondary minimum, and for smaller r(c), q, and K, but diffusion decreased these values. Conversely, straining was dominant for the opposite conditions. Discrepancies in the literature on mechanisms of colloid retention are likely due to a lack of consideration of all of these factors.

TVT-Secur (Hammock) versus TVT-Obturator: a randomized trial of suburethral sling operative procedures.

OBJECTIVES: This study aimed to compare TVT-Secur (TVT-S) and TVT-Obturator (TVT-O) suburethral slings for treatment of stress urinary incontinence (SUI). METHODS: This was a single-center, nonblinded, randomized trial of women with SUI who were randomized to TVT-S or TVT-O from May 2007 to April 2009. The primary outcome, SUI on cough stress test (CST), and quality-of-life and symptom questionnaires (Pelvic Floor Distress Inventory [PFDI-20] and Pelvic Floor Impact Questionnaire [PFIQ-7]) were assessed at 12 weeks and 1 year. RESULTS: Forty-three women were randomized to TVT-S and 44 to TVT-O. There were no differences in median baseline PFDI-20 and PFIQ-7. Twenty-two (52.4%) of 42 participants randomized to TVT-S had a positive CST result at evaluation after 12 weeks or 1 year, whereas 4 (9.1%) of the 44 in the TVT-O group had a positive CST result. The intent-to-treat analysis showed that the risk of a positive CST result was 6 times higher after TVT-S than TVT-O (risk ratio, 6.0; 95% confidence interval [CI], 2.3-16.0). Among women not lost to follow-up, the risk ratio for a positive CST result after TVT-S compared with TVT-O was 17.9 (95% CI, 2.5-128.0) at 12 weeks and 3.5 (95% CI, 1.1-11.0) at 1 year. Both TVT-S and TVT-O resulted in improved quality of life and symptoms at 12 weeks. There was no difference between the groups for PFDI-20 (P = 0.40) or PFIQ-7 (P = 0.43). A similar pattern was seen at 1 year (P = 0.85 and P = 0.36). CONCLUSIONS: The TVT-S seems to have a higher risk of positive postoperative CST result; however, the procedures result in similar improvements in quality of life and symptoms.

Modeling adsorption of liquid mixtures on porous materials.

The multicomponent potential theory of adsorption (MPTA), which was previously applied to adsorption from gases, is extended onto adsorption of liquid mixtures on porous materials. In the MPTA, the adsorbed fluid is considered as an inhomogeneous liquid with thermodynamic properties that depend on the distance from the solid surface (or position in the porous space). The theory describes the two kinds of interactions present in the adsorbed fluid, i.e. the fluid-fluid and fluid-solid interactions, by means of an equation of state and interaction potentials, respectively. The proposed extension of the MPTA onto liquids has been tested on experimental binary and ternary adsorption data. We show that, for the set of experimental data considered in this work, the MPTA model is capable of correlating binary adsorption equilibria. Based on binary adsorption data, the theory can then predict ternary adsorption equilibria. Good agreement with the theoretical predictions is achieved in most of the cases. Some limitations of the model are also discussed.

Normal Versus Noncentral Chi-square Asymptotics of Misspecified Models.

The noncentral chi-square approximation of the distribution of the likelihood ratio (LR) test statistic is a critical part of the methodology in structural equation modeling. Recently, it was argued by some authors that in certain situations normal distributions may give a better approximation of the distribution of the LR test statistic. The main goal of this article is to evaluate the validity of employing these distributions in practice. Monte Carlo simulation results indicate that the noncentral chi-square distribution describes behavior of the LR test statistic well under small, moderate, and even severe misspecifications regardless of the sample size (as long as it is sufficiently large), whereas the normal distribution, with a bias correction, gives a slightly better approximation for extremely severe misspecifications. However, neither the noncentral chi-square distribution nor the theoretical normal distributions give a reasonable approximation of the LR test statistics under extremely severe misspecifications. Of course, extremely misspecified models are not of much practical interest. We also use the Thurstone data ( Thurstone & Thurstone, 1941 ) from a classic study of mental ability for our illustration.

Diffusion measurements in binary liquid mixtures by Raman spectroscopy.

It is shown that Raman spectroscopy allows determination of the molar fractions in mixtures subjected to molecular diffusion. Spectra of three binary systems, benzene/n-hexane, benzene/cyclohexane, and benzene/acetone, were obtained during vertical (exchange) diffusion at several different heights (z) as a function of time. A procedure to determine time-dependent concentration profiles and diffusion coefficients is described in detail for one system, and results are given for the two other cases. For the system benzene/cyclohexane, much lower diffusion coefficients than reported in the literature were found, even in a thermostatically controlled diffusion cell, recording spectra through circulating water. For the system benzene/acetone, the determined diffusion coefficients were in good agreement with the literature data. The limitations of the Raman method are discussed, and it is concluded that many more systems ought to be studied. It is pointed out that diffusion profiles can be obtained in ternary and higher systems, where proper measurements are almost nonexistent.

Synthesis, structure, and magnetic properties of an antiferromagnetic spin-ladder complex: bis(2,3-dimethylpyridinium) tetrabromocuprate.

The complex (2,3-dmpyH)2CuBr4 has been synthesized and its crystal packing determined by single-crystal X-ray diffraction (2,3-dmpyH = 2,3-dimethylpyridinium). The compound crystallizes in the triclinic space group P1. The crystal packing is characterized by the formation of a ladder structure for the CuBr4 anions showing short Br...Br contacts. The rungs of the ladder are formed via a crystallographic inversion center, while the rails are formed via unit cell translations. Variable temperature magnetic susceptibility measurements agree very well with the ladder model [Jrung = -3.10 cm-1 (-4.34 K) and Jrail = -6.02 cm-1 (-8.42 K)]. The assignment as a magnetic ladder is confirmed by first principles bottom-up theoretical calculations which conclude that Jrung = -3.49 cm-1 (-4.89 K) and Jrail = -7.79 cm-1 (-10.9 K), in very good agreement with the experimental values. They also support the absence of additional significant magnetic exchange within the crystals. Thus, (2,3-dmpyH)2CuBr4 represents the second reported example of a weak-exchange limit magnetic ladder (that is, one in which the exchange along the rail is stronger than that across the rung).

Reduction of hysteresis losses in the magnetic refrigerant Gd5Ge2Si2 by the addition of iron.

The magnetocaloric effect is the change in temperature of a material as a result of the alignment of its magnetic spins that occurs on exposure to an external magnetic field. The phenomenon forms the basis for magnetic refrigeration, a concept purported to be more efficient and environmentally friendly than conventional refrigeration systems. In 1997, a 'giant' magnetocaloric effect, between 270 K and 300 K, was reported in Gd5Ge2Si2, demonstrating its potential as a near-room-temperature magnetic refrigerant. However, large hysteretic losses (which make magnetic refrigeration less efficient) occur in the same temperature range. Here we report the reduction (by more than 90 per cent) of these hysteretic losses by alloying the compound with a small amount of iron. This has the additional benefit of shifting the magnetic entropy change peak (a measure of the refrigerator's optimal operating temperature) from 275 K to 305 K, and broadening its width. Although the addition of iron does not significantly affect the refrigerant capacity of the material, a greater net capacity is obtained for the iron-containing alloy when the hysteresis losses are accounted for. The iron-containing alloy is thus a much-improved magnetic refrigerant for near-room-temperature applications.