Quintessence dynamics with two scalar fields and mixed kinetic terms

The dynamical properties of a model of dark energy in which two scalar fields are coupled by a non-canonical kinetic term are studied. We show that overall the addition of the coupling has only minor effects on the dynamics of the two-field system for both potentials studied, even preserving many of the features of the assisted quintessence scenario. The coupling of the kinetic terms enlarges the regions of stability of the critical points. When the potential is of an additive form, we find the kinetic coupling has an interesting effect on the dynamics of the fields as they approach the inflationary attractor, with the result that the combined equation of state of the scalar fields can approach -1 during the transition from a matter dominated universe to the recent period of acceleration.Comment: 14 pages, 9 figures. Includes a extra section describing the case of a field-dependent coupling with two additional figures and minor changes to match published versio

Investigation looking at the repeatability of 20 Society of Master Saddlers (SMS) qualified saddle fitters’ observations during static saddle fit

Saddle fit is widely considered to be a crucial factor for the health and performance of riding horses; however, there have been no studies looking at the agreement between professionals who fit and assess saddles. The aim of the study was to determine the agreement between Society of Master Saddlers (SMSs) qualified saddle fitters when statically fitting a saddle following the SMS guidelines. Twenty SMS qualified saddle fitter volunteers were recruited via social media and asked to statically assess the fit of the saddle following the “7 points of saddle fit” guidelines of the SMS in 10 horses. Descriptive statistics and Fleiss Kappa (as a measure of agreement beyond chance) were used to determine agreement between fitters. Agreement varied from slight to substantial between the different saddle assessment criteria with the assessment of overall saddle fit resulting in a fair agreement of k = 0.32. Substantial agreement was found for saddle clearance front (k = 0.66), top (k = 0.78), and rear (k = 0.81). Fair agreement was found for clearance of the saddle—side (k = 0.28) and how the girth straps line up with girth groove (k = 0.31) and panel contact (k = 0.38). Slight agreement was found for tree width and length (k = 0.12) and tree length (k = 0.12). Horse height in some criteria affected agreement. Agreement varied between the standard criteria. In cases where it was difficult to visually evaluate saddle fit, agreement was lower. Further work should aim to standardize the criteria which had suboptimal agreement

Magnetic properties of PrCu2_2 at high pressure

We report a study of the low-temperature high-pressure phase diagram of the intermetallic compound PrCu$_2$, by means of molecular-field calculations and $^{63,65}$Cu nuclear-quadrupole-resonance (NQR) measurements under pressure. The pressure-induced magnetically-ordered phase can be accounted for by considering the influence of the crystal electric field on the $4f$ electron orbitals of the Pr$^{3+}$ ions and by introducing a pressure-dependent exchange interaction between the corresponding local magnetic moments. Our experimental data suggest that the order in the induced antiferromagnetic phase is incommensurate. The role of magnetic fluctuations both at high and low pressures is also discussed.Comment: 7 pages, 6 figures, submitted to Eur. Phys. J.

Chemotherapie von Hirntumoren bei Erwachsenen

Zusammenfassung: Die Chemotherapie hat sich zu einer wesentlichen Säule der Hirntumortherapie entwickelt. Ihr Stellenwert in der Therapie der Gliome ist nicht mehr nur auf die Rezidivtherapie beschränkt. Die Chemotherapie mit Temozolomid ist heute Standard in der Primärtherapie des Glioblastoms. Zur Optimierung der Chemotherapie werden derzeit zahlreiche große Studien durchgeführt, die sich auf den Nachweis einer Methylierung der Promoterregion des MGMT-Gens und eines Verlusts genetischen Materials auf den Chromosomenabschnitten 1p und 19q stützen. Außerhalb solcher Studien wird die Chemotherapie sowohl als Zusatztherapie als auch als Alternative zur Strahlentherapie vor allem bei anaplastischen oligodendroglialen Tumoren und niedriggradigen Gliomen eingesetzt. Primäre Lymphome des Zentralnervensystems sind vermutlich die einzigen Hirntumoren, die mit alleiniger Chemotherapie kurativ behandelt werden können. Bei Hirnmetastasen folgen die Konzepte für die Chemotherapie der für den jeweiligen Primärtumor indizierten Chemotherapie. Zudem werden Strategien der kombinierten Radiochemotherapie mit Temozolomid und mit Topotecan verfolgt. Bei der Meningeosis neoplastica werden je nach Ausbreitungsmuster der Tumorerkrankung Strahlentherapie, systemische Chemotherapie und intrathekale Chemotherapie kombinier

How does the local wind field control the aerosol distribution in coastal Dronning Maud Land?

Atmospheric circulation patterns and chemical concentrations in firn cores are highly related to each other. Atmospheric winds transport aerosols like sea salt and mineral dust over the globe and redistribute them. Because of this, it is possible to reconstruct atmospheric circulation bringing aerosol to Antarctica by analyzing chemical impurities in firn and ice. With these analyses, the gap caused by sparse atmospheric measurements can be filled and this knowledge can then be used to improve the understanding of local and global circulation patterns.Due to a very high accumulation rate (~600 kg/m²*a), coastal Dronning Maud Land (CDML) is a perfect site to conduct these studies.Here, the upper 6m of two firn cores drilled on Halvfaryggen and Sörasen (covering the time interval from 2002- 2007) were analyzed on ionic concentrations. This data was then contrasted to measurements from the air chemistry laboratories at Neumayer (NM) and Kohnenstation (KS), and synoptic measurements from automatic weather stations (distributed in CDML and at NM).The analyses show very different results: Sea salt ions (e.g. Na+) are higher correlated to ions measured in aerosol samples at the air chemistry laboratory at KS than to the one located at NM. In contrast, ions representing mineral dust (e.g. nss-Ca2+) only have a weak correlation over the whole area and time period. Accordingly, the deposition of aerosol is highly dependent on its origin and the topography in coastal Antarctica suggesting different transport pathways for sea level and higher altitude sites

Plate tectonics: When ancient continents collide

The geological record preserves scant evidence for early plate tectonics. Analysis of eclogites — metamorphic rocks formed in subduction zones — in the Trans-Hudson mountain belt suggests modern-style subduction may have operated 1,800 million years ago