Locating the pseudogap closing point in cuprate superconductors: absence of entrant or reentrant behavior

Current descriptions of the pseudogap in underdoped cuprates envision a doping-dependent transition line $T^*(p)$ which descends monotonically towards zero just beyond optimal doping. There is much debate as to the location of the terminal point $p^*$ where $T^*(p)$ vanishes, whether or not there is a phase transition at $T^*$ and exactly how $T^*(p)$ behaves below $T_c$ within the superconducting dome. One perspective sees $T^*(p)$ cutting the dome and continuing to descend monotonically to zero at $p_{crit} \approx 0.19$ holes/Cu $-$ referred to here as `entrant behavior'. Another perspective derived from photoemission studies is that $T^*(p)$ intersects the dome near $p_{crit} \approx 0.23$ holes/Cu then turns back below $T_c$, falling to zero again around $p_{crit} \approx 0.19$ $-$ referred to here as `reentrant behavior'. By examining thermodynamic data for Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ we show that neither entrant nor reentrant behavior is experimentally supported. Rather, $p_{crit} \approx 0.19$ sharply delimits the pseudogap regime and for $p < 0.19$ the pseudogap is always present, independent of temperature. Similar results are found for Y$_{0.8}$Ca$_{0.2}$Ba$_2$Cu$_3$O$_{7-\delta}$. For both materials $T^*(p)$ is not a temperature but a crossover scale, $\approx E^*(p)/2k_B$, reflecting instead the underlying pseudogap energy $E^*(p)$ which vanishes as $p \rightarrow 0.19$.Comment: 20 Pages, 9 Figures, in press Phys. Rev.

Landsat Data Continuity Mission Expected Instrument Performance

The Landsat Data Continuity Mission (LDCM) is scheduled for a December 2012 launch date. LDCM is being managed by an interagency partnership between NASA and the U.S. Geological Survey (USGS). In order to provide the necessary spectral coverage of the visible through shortwave-infrared (SWIR) and the thermal-infrared (TIR), the satellite will carry two sensors. The Operational Land Imager (OLI) will collect data for nine visible to shortwave spectral bands with a spatial resolution of 30 m (with a 15 m panchromatic band). The Thermal Infrared Sensor (TIRS) will collect coincident image data for two TIR bands with a spatial resolution of 100 m. The OLI is fully assembled and tested and has been shipped by it's manufacturer, Ball Aerospace and Technology Corporation, to the Orbital Sciences Corporation (Orbital) facility where it is being integrated onto the LDCM spacecraft. Pre-launch testing indicates that OLI will meet all performance specification with margin. TIRS is in development at the NASA Goddard Space F!ight Center (GSFC) and is in final testing before shipping to the Orbital facility in January, 2012. The presentation will describe the LDCM satellite instrument systems, present pre-launch performance data for OLI and TIRS, and present simulated images to highlight notable features and expected imaging performance

Landsat Data Continuity Mission Calibration and Validation

The primary payload for the Landsat Data Continuity Mission (LDCM) is the Operational Land Imager (OLI), being built by Ball Aerospace and Technologies, under contract to NASA. The OLI has spectral bands similar to the Landsat-7 ETM+, minus the thermal band and with two new bands, a 443 nm band and 1375 nm cirrus detection band. On-board calibration systems include two solar diffusers (routine and pristine), a shutter and three sets of internal lamps (routine, backup and pristine). Being a pushbroom opposed to a whiskbroom design of ETM+, the system poses new challenges for characterization and calibration, chief among them being the large focal plane with 75000+ detectors. A comprehensive characterization and calibration plan is in place for the instrument and the data throughout the mission including Ball, NASA and the United States Geological Survey, which will take over operations of LDCM after on-orbit commissioning. Driving radiometric calibration requirements for OLI data include radiance calibration to 5% uncertainty (1 q); reflectance calibration to 3% uncertainty (1 q) and relative (detector-to-detector) calibration to 0.5% (J (r). Driving geometric calibration requirements for OLI include bandto- band registration of 4.5 meters (90% confidence), absolute geodetic accuracy of 65 meters (90% CE) and relative geodetic accuracy of 25 meters (90% CE). Key spectral, spatial and radiometric characterization of the OLI will occur in thermal vacuum at Ball Aerospace. During commissioning the OLI will be characterized and calibrated using celestial (sun, moon, stars) sources and terrestrial sources. The USGS EROS ground processing system will incorporate an image assessment system similar to Landsat-7 for characterization and calibration. This system will have the added benefit that characterization data will be extracted as part of the normal image data processing, so that the characterization data available will be significantly larger than for Landsat-7 ETM+

Extrasolar planet science with the Antarctic planet interferometer

The primary limitation to ground based astronomy is the Earth's atmosphere. The atmosphere above the Antarctic plateau is different in many regards compared to the atmosphere at temperate sites. The extreme altitude, cold and low humidity offer a uniquely transparent atmosphere at many wavelengths. Studies at the South Pole have shown additionally that the turbulence properties of the night time polar atmosphere are fundamentally different to mid latitudes. Despite relatively strong ground layer turbulence, the lack of high altitude turbulence combined with low wind speeds presents favorable conditions for interferometry. The unique properties of the polar atmosphere can be exploited for Extrasolar Planet studies with differential astrometry, differential phase and nulling intereferometers. This paper combines the available data on the properties of the atmosphere at the South Pole and other Antarctic plateau sites for Extrasolar Planet science with interferometry

Pharmacodynamics, pharmacokinetics, and safety of single-dose subcutaneous administration of selatogrel, a novel P2Y12 receptor antagonist, in patients with chronic coronary syndromes

Aims  To study the pharmacodynamics and pharmacokinetics of selatogrel, a novel P2Y12 receptor antagonist for subcutaneous administration, in patients with chronic coronary syndromes (CCS). Methods and results  In this double-blind, randomized study of 345 patients with CCS on background oral antiplatelet therapy, subcutaneous selatogrel (8 mg, n = 114; or 16 mg, n = 115) was compared with placebo (n = 116) (ClinicalTrials.gov: NCT03384966). Platelet aggregation was assessed over 24 h (VerifyNow assay) and 8 h (light transmittance aggregometry; LTA). Pharmacodynamic responders were defined as patients having P2Y12 reaction units (PRU) <100 at 30 min post-dose and lasting ≥3 h. At 30 min post-dose, 89% of patients were responders to selatogrel 8 mg, 90% to selatogrel 16 mg, and 16% to placebo (P < 0.0001). PRU values (mean ± standard deviation) were 10 ± 25 (8 mg), 4 ± 10 (16 mg), and 163 ± 73 (placebo) at 15 min and remained <100 up to 8 h for both doses, returning to pre-dose or near pre-dose levels by 24 h post-dose. LTA data showed similarly rapid and potent inhibition of platelet aggregation. Selatogrel plasma concentrations peaked ∼30 min post-dose. Selatogrel was safe and well-tolerated with transient dyspnoea occurring overall in 7% (16/229) of patients (95% confidence interval: 4–11%). Conclusions  Selatogrel was rapidly absorbed following subcutaneous administration in CCS patients, providing prompt, potent, and consistent platelet P2Y12 inhibition sustained for ≥8 h and reversible within 24 h. Further studies of subcutaneous selatogrel are warranted in clinical scenarios where rapid platelet inhibition is desirable

P2Y12 platelet inhibition in clinical practice

Platelet adhesion, activation and aggregation play a pivotal role in atherothrombosis. Intracoronary atherothrombosis is the most common cause of the development of acute coronary syndrome (ACS), and plays a central role in complications occurring around percutaneous coronary intervention (PCI) including recurrent ACS, procedure-related myocardial infarction or stent thrombosis. Inhibition of platelet aggregation by medical treatment impairs formation and progression of thrombotic processes and is therefore of great importance in the prevention of complications after an ACS or around PCI. An essential part in the platelet activation process is the interaction of adenosine diphosphate (ADP) with the platelet P2Y12 receptor. The P2Y12 receptor is the predominant receptor involved in the ADP-stimulated activation of the glycoprotein IIb/IIIa receptor. Activation of the glycoprotein IIb/IIIa receptor results in enhanced platelet degranulation and thromboxane production, and prolonged platelet aggregation. The objectives of this review are to discuss the pharmacological limitations of the P2Y12 inhibitor clopidogrel, and describe the novel alternative P2Y12 inhibitors prasugrel and ticagrelor and the clinical implications of the introduction of these new medicines

Extrasolar planet science with the Antarctic planet interferometer

The primary limitation to ground based astronomy is the Earth's atmosphere. The atmosphere above the Antarctic plateau is different in many regards compared to the atmosphere at temperate sites. The extreme altitude, cold and low humidity offer a uniquely transparent atmosphere at many wavelengths. Studies at the South Pole have shown additionally that the turbulence properties of the night time polar atmosphere are fundamentally different to mid latitudes. Despite relatively strong ground layer turbulence, the lack of high altitude turbulence combined with low wind speeds presents favorable conditions for interferometry. The unique properties of the polar atmosphere can be exploited for Extrasolar Planet studies with differential astrometry, differential phase and nulling intereferometers. This paper combines the available data on the properties of the atmosphere at the South Pole and other Antarctic plateau sites for Extrasolar Planet science with interferometry