We present spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.16 " z " 0.62. The luminosity distances of these objects are determined by methods that employ relations between SN Ia luminosity and light curve shape. Combined with previous data from our High-z Supernova Search Team and recent results by Riess et al., this expanded set of 16 high-redshift supernovae and a set of 34 nearby supernovae are used to place constraints on the following cosmo- logical parameters: the Hubble constant the mass density the cosmological constant (i.e., the (H 0 ), () M ), vacuum energy density, the deceleration parameter and the dynamical age of the universe ) " ), (q 0 ), ) M \ 1) methods. We estimate the dynamical age of the universe to be 14.2 ^ 1.7 Gyr including systematic uncer- tainties in the current Cepheid distance scale. We estimate the likely e†ect of several sources of system- atic error, including progenitor and metallicity evolution, extinction, sample selection bias, local perturbations in the expansion rate, gravitational lensing, and sample contamination. Presently, none of these e†ects appear to reconcile the data with and ) " \ 0 q 0 " 0.

/pdf/observational-evidence-from-supernovae-for-an-accelerating-2hxji77uix.pdf

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant

We created a new dataset of spatially interpolated monthly climate data for global land areas at a very high spatial resolution (approximately 1 km2). We included monthly temperature (minimum, maximum and average), precipitation, solar radiation, vapour pressure and wind speed, aggregated across a target temporal range of 1970–2000, using data from between 9000 and 60 000 weather stations. Weather station data were interpolated using thin-plate splines with covariates including elevation, distance to the coast and three satellite-derived covariates: maximum and minimum land surface temperature as well as cloud cover, obtained with the MODIS satellite platform. Interpolation was done for 23 regions of varying size depending on station density. Satellite data improved prediction accuracy for temperature variables 5–15% (0.07–0.17 °C), particularly for areas with a low station density, although prediction error remained high in such regions for all climate variables. Contributions of satellite covariates were mostly negligible for the other variables, although their importance varied by region. In contrast to the common approach to use a single model formulation for the entire world, we constructed the final product by selecting the best performing model for each region and variable. Global cross-validation correlations were ≥ 0.99 for temperature and humidity, 0.86 for precipitation and 0.76 for wind speed. The fact that most of our climate surface estimates were only marginally improved by use of satellite covariates highlights the importance having a dense, high-quality network of climate station data.

WorldClim 2: new 1-km spatial resolution climate surfaces for global land areas

Living in an oxygenated environment has required the evolution of effective cellular strategies to detect and detoxify metabolites of molecular oxygen known as reactive oxygen species. Here we review evidence that the appropriate and inappropriate production of oxidants, together with the ability of organisms to respond to oxidative stress, is intricately connected to ageing and life span.

Oxidants, oxidative stress and the biology of ageing.

[1] We present a 53-Myr stack (the “LR04” stack) of benthic δ18O records from 57 globally distributed sites aligned by an automated graphic correlation algorithm This is the first benthic δ18O stack composed of more than three records to extend beyond 850 ka, and we use its improved signal quality to identify 24 new marine isotope stages in the early Pliocene We also present a new LR04 age model for the Pliocene-Pleistocene derived from tuning the δ18O stack to a simple ice model based on 21 June insolation at 65°N Stacked sedimentation rates provide additional age model constraints to prevent overtuning Despite a conservative tuning strategy, the LR04 benthic stack exhibits significant coherency with insolation in the obliquity band throughout the entire 53 Myr and in the precession band for more than half of the record The LR04 stack contains significantly more variance in benthic δ18O than previously published stacks of the late Pleistocene as the result of higher-resolution records, a better alignment technique, and a greater percentage of records from the Atlantic Finally, the relative phases of the stack's 41- and 23-kyr components suggest that the precession component of δ18O from 27–16 Ma is primarily a deep-water temperature signal and that the phase of δ18O precession response changed suddenly at 16 Ma

/pdf/a-pliocene-pleistocene-stack-of-57-globally-distributed-n5iphe7mt2.pdf

A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records

The Lancet Commission on pollution and health

China has recently made available hourly air pollution data from over 1500 sites, including airborne particulate matter (PM), SO2, NO2, and O3. We apply Kriging interpolation to four months of data to derive pollution maps for eastern China. Consistent with prior findings, the greatest pollution occurs in the east, but significant levels are widespread across northern and central China and are not limited to major cities or geologic basins. Sources of pollution are widespread, but are particularly intense in a northeast corridor that extends from near Shanghai to north of Beijing. During our analysis period, 92% of the population of China experienced >120 hours of unhealthy air (US EPA standard), and 38% experienced average concentrations that were unhealthy. China’s population-weighted average exposure to PM2.5 was 52 μg/m3. The observed air pollution is calculated to contribute to 1.6 million deaths/year in China [0.7–2.2 million deaths/year at 95% confidence], roughly 17% of all deaths in China.

/pdf/air-pollution-in-china-mapping-of-concentrations-and-sources-4iv6fc8tsv.pdf

Air Pollution in China: Mapping of Concentrations and Sources.

With the posthumously published A Compendium of Fossil Marine Animal Genera, Jack Sepkoski initiated a new wave in palaeontology: the exploration of major patterns in the history of life as recorded by compilations of taxonomic data. This database, which records first and last stratigraphic appearances of over 36,000 marine genera, has been reanalysed in the light of the latest stratigraphic time scales, and a previously unrecognized 62-million-year cycle in the diversity of fossil genera emerges. As yet there is no explanation, but various models involving climate, environment, geological and astrophysical factors should provide testable predictions to help solve the mystery. It is well known that the diversity of life appears to fluctuate during the course of the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0–542 million years ago). Here we show, using Sepkoski's compendium1 of the first and last stratigraphic appearances of 36,380 marine genera, a strong 62 ± 3-million-year cycle, which is particularly evident in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski2 may be an aspect of this cycle. Because of the high statistical significance we also consider the contributions of environmental factors, and possible causes.

/pdf/cycles-in-fossil-diversity-1el5ot7z74.pdf

Cycles in fossil diversity

By considering radioisotope dating as a problem in trace element detection, and by using the cyclotron as a high-energy mass spectrometer for this purpose, we have shown that one can greatly increase the maximum age that can be determined while simultaneously reducing the size of the sample required. The cyclotron can be used to detect atoms or simple molecules that are present at the 10-16 level or greater. For 14C dating one should be able to go back 40,000 to 100,000 years with 1- to 100-mg carbon samples; for 10Be dating, 10 to 30 million years with 1-mm3 to 10-cm3 rock samples; for tritium dating, 160 years with a 1-liter water sample. The feasibility of the technique has been demonstrated experimentally by measuring the tritium/deuterium ratio in a sample 24 years old. For samples many half-lives old, the fractional error in the age is small even if rates of production or deposition of the isotopes. Although cyclotrons are expensive to build, their operating costs are relatively low. If several samples are dated per hour the cost per date may not be substantially higher than it is today for decay dating. There are already more than 50 cyclotrons in operation which have the potential to do radioisotope dating, and their application to important problems of dating and trace element analysis should prove very fruitful.

/pdf/radioisotope-dating-with-a-cyclotron-4prxqdb5yt.pdf

Radioisotope dating with a cyclotron.

Cycles in Fossil Diversity Robert A. Rohde & Richard A. Muller Department of Physics and Lawrence Berkeley Laboratory University of California, Berkeley California 94720 USA Report LBNL-56544 20 October 2004 submitted to Nature It is well-known that the diversity of life appears to fluctuate during the course the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0-542 Ma). Using Sepkoski's compendium 1 of the first and last stratigraphic appearances of 36380 marine genera, we report a strong 62 ± 3 Myr cycle, which is particularly strong in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski 2 may be an aspect of this cycle. Because of the high stastical significance, we also consider contributing environmental factors and possible causes. Sepkoski's posthumously published Compendium of Fossil Marine Animal Genera , and its earlier versions, has frequently been used in the study of biodiversity and extinction 3-4 . For our purposes, diversity is defined as the number of distinct genera alive at any given time, i.e. those whose first occurrence predates and last occurrence postdates that time. Because Sepkoski references only 295 stratigraphic intervals, the International Commission on Stratigraphy's 2004 time scale 5 is used to translate the stratigraphic records into a record of diversity vs. time, with details given in the supplement. Though Sepkoski's is the most extensive compilation available, it is known to be subject to certain systematic limitations due primarily to the varying availability and quality of geologic sections 6-7 , the implications of this will be discussed where appropriate. Fig. 1A shows diversity vs. time for all 36380 genera in Sepkoski’s compendium. In Fig. 1B we show the 17797 genera that remain when we remove those with uncertain ages (given only at epoch or period level), and those with only a single occurrence. The smooth trend curve through the data is the third-order polynomial that minimizes the variance of the difference between it and the data. The overall shape of 1A and 1B is similar to those previously published for fossil families 2 and for genera 3 . It rises rapidly at the beginning of the Phanerozoic (right side), drops to a nadir near the Permian- Triassic boundary (251 Ma), and then rises steeply until the present. These variations may result from evolutionary and environmental drivers 8 , observational biases 6 , or changes in the number of available geologic sections 7 ; for example, the sharp rise towards the present may be driven by the greater availability and study of recent sections. Our focus is not on the trend but on the short-term variations shown in 1C, obtained by subtracting the trend from 1B. The Fourier spectrum of 1C is shown in 1E. It is dominated by a strong peak with period 62 ± 3 Myr (frequency 0.016 cycles/Myr). The sine wave corresponding to this cycle is also shown in Fig. 1C, where it accounts for 35% of the variance. Note that because steep drops in diversity are often followed by gradual recoveries, the peaks and valleys in the data don’t precisely align with those of the sine curve. Also, some abrupt features may appear more gradual because of incomplete records. 9 We indicate the 5 major extinction events of Raup and Sepkoski 2

/pdf/cycles-in-fossil-diversity-1m7qdvhaqu.pdf

Lunar spherules are small glass beads that are formed mainly as a result of small impacts on the lunar surface; the ages of these impacts can be determined by the 40 Ar/ 39 Ar isochron technique. Here, 155 spherules separated from 1 gram of Apollo 14 soil were analyzed using this technique. The data show that over the last ∼3.5 billion years, the cratering rate decreased by a factor of 2 to 3 to a low about 500 to 600 million years ago, then increased by a factor of 3.7 ± 1.2 in the last 400 million years. This latter period coincided with rapid biotic evolutionary radiation on Earth.

https://science.sciencemag.org/content/sci/287/5459/1785.full.pdf

Lunar Impact History from 40Ar/39Ar Dating of Glass Spherules

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Air Pollution in China: Mapping of Concentrations and Sources.

Cycles in fossil diversity

Radioisotope dating with a cyclotron.

Cycles in fossil diversity

Lunar Impact History from 40Ar/39Ar Dating of Glass Spherules