The Colorado Plateau Coring Project (CPCP): 100 Million Years of Earth System History

Lasting over 100 million years, the early Mesozoic (252 to 145 Ma) is punctuated by two of the five major mass extinctions of the Phanerozoic (Permo-Triassic and Triassic-Jurassic) plus several smaller extinction events. It witnessed the evolutionary appearance of the modem terrestrial biota including frogs, salamanders, turtles, lizards, crocodilians, dinosaurs, birds, and mammals, and spans a time of dramatic climate changes on the continents. What is arguably the richest record of these events lies in the vast (- 2.5 million km2) complex of epicontinental basins in the western part of Pangea, now largely preserved on the Colorado Plateau (Fig.l). Since the mid-19th century, classic studies of these basins, their strata, and their fossils have made this succession instrumental in framing our context of the early Mesozoic Earth system as reflected in the international literature. Despite this long and distinguished history of study of the Colorado Plateau region, striking ambiguities in temporal resolution, major uncertainties in global correlations, and significant doubts about paleolatitudinal position hamper incorporation of the huge amount of information from the region into-tests of major competing climatic, biotic, and tectonic hypotheses and a fundamental understanding of Earth system processes

Trust and normative control in multi-agent systems: an empirical study

Despite relevant insights from socio-economics, little research in multi-agent systems has addressed the interconnections between trust and normative notions such as contracts and sanctions. Focusing our attention on scenarios of betrayal, in this paper we combine the use of trust and sanctions in a negotiation process. We describe a scenario of dyadic relationships between truster agents, which make use of trust and/or sanctions, and trustees characterized by their ability and integrity, which may influence their attitude toward betrayal. Both agent behavior models are inspired in socio-economics literature. Through simulation, we show the virtues and shortcomings of exploiting trust, sanctions and a combination of both

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early-Type Galaxies

We determine the relative rates of short GRBs in cluster and field early-type galaxies as a function of the age probability distribution of their progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the difference in the growth of stellar mass in clusters and in the field, which arises from the combined effects of the galaxy stellar mass function, the early-type fraction, and the dependence of star formation history on mass and environment. This approach complements the use of the early- to late-type host galaxy ratio, with the added benefit that the star formation histories of early-type galaxies are simpler than those of late-type galaxies, and any systematic differences between progenitors in early- and late-type galaxies are removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n = -2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2, corresponding to n ~ 0 - 1. This is similar to the value inferred from the ratio of short GRBs in early- and late-type hosts, but it differs from the value of n ~ -1 for NS binaries in the Milky Way. We stress that this general approach can be easily modified with improved knowledge of the effects of environment and mass on the build-up of stellar mass, as well as the effect of globular clusters on the short GRB rate. It can also be used to assess the age distribution of Type Ia supernova progenitors.Comment: ApJ accepted versio

Temperature quenching of yellow Ce3+ luminescence in YAG:Ce

Yttrium aluminum garnet (YAG) doped with Ce3+ is the phosphor of choice for the conversion of blue to yellow light in the rapidly expanding market of white light LEDs, but it is generally thought to suffer from a low luminescence quenching temperature. The luminescence quenching temperature is an important parameter, especially in high-power LEDs, but surprisingly no systematic research has been done to measure and understand the temperature quenching of the yellow Ce luminescence in YAG:Ce. Here we report on the luminescence temperature quenching in YAG:Ce. For a wide range of Ce concentrations (between 0.033% and 3.3%) the temperature dependence of the emission intensity and the luminescence lifetimes are reported. The intrinsic quenching temperature of the Ce luminescence is shown to be very high (>700 K). The lower quenching temperatures reported in the literature are explained by thermally activated concentration quenching (for highly doped systems) and the temperature dependence of the oscillator strength (for low doping concentrations). In addition, high-resolution spectra are reported, which provide insight into the position of the zero-phonon transition (20450 cm-1), the Stokes shift (2400 cm-1), the energy of the dominant phonon mode (200 cm-1), and the Huang-Rhys parameter (S ) 6). These parameters are compared with ab initio calculations on the position of and relaxation in the excited 5d state of Ce3+ in YAG, which can aid in providing a better theoretical understanding of the temperature quenching

Luminescence properties of SrSi2AlO2N3 doped with divalent rare-earth ions

The optical properties of SrSi2AlO2N3 doped with Eu2+ and Yb2+ are investigated towards their applicability in LEDs. The Eu2+-doped material shows emission in the green, peaking around 500 nm. The emission is ascribed to the 4f65d1–4f7 transition on Eu2+. In view of the too low quantum efficiency and the considerable thermal quenching of the emission at the operation temperature of high power LED (>1W/mm2) this phosphor is only suitable for application in low power LEDs. The Yb2+ emission shows an anomalously red-shifted emission compared to Eu2+, which is characterized by a larger FWHM, a larger Stokes shift and lower thermal quenching temperature. The emission is ascribed to self-trapped exciton emission. The Yb2+ activated phosphor is found to be unsuitable for the use in any phosphor-converted LEDs

Color point tuning for (Sr,Ca,Ba)Si2O2N2:Eu2+ for white light LEDs

Color point tuning is an important challenge for improving white light LEDs. In this paper, the possibilities of color tuning with the efficient LED phosphor Sr1-x-y-zCaxBaySi2O2N2:Euz 2+ (0 e x, y e 1; 0.005 e z e 0.16) are investigated. The emission color can be tuned in two ways: by changing Eu2+ concentration and by substitution of the host lattice cation Sr2+ by either Ca2+ or Ba2+. The variation in the Eu2+ concentration shows a red shift of the emission upon increasing the Eu concentration above 2%. The red shift is explained by energy migration and energy transfer to Eu2+ ions emitting at longer wavelengths. Along with this (desired) red shift there is an (undesired) lowering of the quantum efficiency and the thermal quenching temperature due to concentration quenching. Partial substitution of Sr2+ by either Ca2+ or Ba2+ also results in a red-shifted Eu2+ emission. For Ca2+ this is expected and the red shift is explained by an increased crystal field splitting for Eu2+ on the (smaller) Ca2+ cation site. For Ba2+, the red shift is surprising. Often, a blue shift of the fd emission is observed in case of substitution of Sr2+ by the larger Ba2+ cation. The Eu2+ emission in the pure BaSi2O2N2 host lattice is indeed blue-shifted. Temperature dependent luminescence measurements show that the quenching temperature drops upon substitution of Sr by Ca, whereas for Ba substitution, the quenching temperature remains high. Color tuning by partial substitution of Sr2+ by Ba2+ is therefore the most promising way to shift the color point of LEDs while retaining the high quantum yield and high luminescence quenching temperature

Effectiveness and cost-effectiveness of salicylic acid and cryotherapy for cutaneous warts: an economic decision model

Objectives: To estimate the costs of commonly used treatments for cutaneous warts, as well as their health benefits and risk. To create an economic decision model to evaluate the cost-effectiveness of these treatments, and, as a result, assess whether a randomised controlled trial (RCT) would be feasible and cost-effective. Data sources: Focus groups, structured interviews and observation of practice. Postal survey sent to 723 patients. A recently updated Cochrane systematic review and published cost and prescribing data. Review methods: Primary and secondary data collection methods were used to inform the development of an economic decision model. Data from the postal survey provided estimates of the effectiveness of wart treatments in a primary care setting. These estimates were compared with outcomes reported in the Cochrane review of wart treatment, which were largely obtained from RCTs conducted in secondary care. A decision model was developed including a variety of over-the-counter (OTC) and GPprescribed treatments. The model simulated 10,000 patients and adopted a societal perspective. Results: OTC treatments were used by a substantial number of patients (57%) before attending the GP surgery. By far the most commonly used OTC preparation was salicylic acid (SA). The results of the economic model suggested that of the treatments prescribed by a GP, the most cost-effective treatment was SA, with an incremental cost-effectiveness ratio (ICER) of 2.20 £/% cured. The ICERs for cryotherapy varied widely (from 1.95 to 7.06 £/% cured) depending on the frequency of applications and the mode of delivery. The most cost-effective mode of delivery was through nurse-led cryotherapy clinics (ICER = 1.95 £/% cured) and this could be a cost-effective alternative to GP-prescribed SA. Overall, the OTC therapies were the most cost-effective treatment options. ICERs ranged from 0.22 £/% cured for OTC duct tape and 0.76 £/% cured for OTC cryotherapy to 1.12 £/% cured for OTC SA. However, evidence in support of OTC duct tape and OTC cryotherapy is very limited. Side-effects were commonly reported for both SA and cryotherapy, particularly a burning sensation, pain and blistering. Conclusions: Cryotherapy delivered by a doctor is an expensive option for the treatment of warts in primary care. Alternative options such as GP-prescribed SA and nurse-led cryotherapy clinics provide more costeffective alternatives, but are still expensive compared with self-treatment. Given the minor nature of most cutaneous warts, coupled with the fact that the majority spontaneously resolve in time, it may be concluded that a shift towards self-treatment is warranted. Although both duct tape and OTC cryotherapy appear promising new self-treatment options from both a cost and an effectiveness perspective, more research is required to confirm the efficacy of these two methods of wart treatment. If these treatments are shown to be as cost-effective as or more cost-effective than conventional treatments, then a shift in service delivery away from primary care towards more OTC treatment is likely. A public awareness campaign would be useful to educate patients about the self-limiting nature of warts and the possible alternative OTC treatment options available. Two future RCTs are recommended for consideration: a trial of SA compared with nurse-led cryotherapy in primary care, and a trial of home treatments. Greater understanding of the efficacy of these home treatments will give doctors a wider choice of treatment options, and may help to reduce the overall demand for cryotherapy in primary care