K_l3 form factors at order p^6 in chiral perturbation theory

This paper describes the calculation of the semileptonic K_l3 decay form factor at order p^6 of chiral perturbation theory which is the next-to-leading order correction to the well-known p^4 result achieved by Gasser and Leutwyler. At order p^6 the chiral expansion contains 1- and 2-loop diagrams which are discussed in detail. The irreducible 2-loop graphs of the sunset topology are calculated numerically. In addition, the chiral Lagrangian L^6 produces direct couplings with the W-bosons. Due to these unknown couplings, one can always add linear terms in q^2 to the predictions of the form factor f_-(q^2). For the form factor f_+(q^2), this ambiguity involves even quadratic terms. Making use of the fact that the pion electromagnetic form factor involves the same q^4 counter term, the q^4-ambiguity can be resolved. Apart from the possibility of adding an arbitrary linear term in q^2 our calculation shows that chiral perturbation theory converges very well in this application, as the O(p^6) corrections are small. Comparing the predictions of chiral perturbation theory with the recent CPLEAR data, it is seen that the experimental form factor f_+(q^2) is well described by a linear fit, but that the slope lambda_+ is smaller by about 2 standard deviations than the O(p^4) prediction. The unavoidable q^2 counter term of the O(p^6) corrections allows to bring the predictions of chiral perturbation theory into perfect agreement with experiment.Comment: 32 pages, 7 figure

Constitutive behaviour of the metastable stainless steel: Sandvik Nanoflex

This article presents a model to describe the constitutive behaviour of corrosion-resistant Sandvik steel NanoflexTM [1] during metal forming and hardening. This material is characterised by different phenomena. The material is metastable, which causes strain-induced transformation to take place during metal forming. Depending on the annealing conditions, the material also transforms isothermally [2, 3] (as opposed to a-thermal martensite). This transformation can also take place immediately after forming, as a result of the residual stresses present in the material. The martensite phase of this material can be aged [4]. Results of the various measurements on Sandvik NanoflexTM are shown. The measurements mainly involved tensile tests and upsetting tests, during which both isothermal transformation and strain-induced transformation were measured by inductive sensors[5] and they were afterwards examined. The hardening of the material and the increase in hardness during ageing was also examined.\ud Finally, a constitutive model based on literature and the measurement are presented. This model describes the isothermal,\ud stress-assisted transformation, strain-induced transformation, work hardening and ageing. The model has been set up in such\ud a way that it can be simply implemented in a FEM cod

K0 form factor at order p^6 of chiral perturbation theory

This paper describes the calculation of the electromagnetic form factor of the K0 meson at order p^6 of chiral perturbation theory which is the next-to-leading order correction to the well-known p^4 result achieved by Gasser and Leutwyler. On the one hand, at order p^6 the chiral expansion contains 1- and 2-loop diagrams which are discussed in detail. Especially, a numerical procedure for calculating the irreducible 2-loop graphs of the sunset topology is presented. On the other hand, the chiral Lagrangian L^6 produces a direct coupling of the K0 current with the electromagnetic field tensor. Due to this coupling one of the unknown parameters of L^6 occurs in the contribution to the K0 charge radius.Comment: 22 pages Latex with 8 figures, Typos corrected, one reference adde

Observations on North Dakota Sponges (Haplosclerina: Spongillidae) and Sisyrids (Neuroptera: Sisyridae)

Factors influencing occurrence, distribution, and ecology of sponges and sisyrids are discussed, with emphasis on northeastern North Dakota. New state records for North Dakota sponges, Eunapius Jraguis Leidy and Ephydatia fluviatilis L. and the sisyrids, Sisyra vicaria (Hagen) and Climacia areolaris (Hagen), and new county records for C. areolaris in northwestern Minnesota and Eunapius fragilis in northeastern North Dakota are reported. A rare association of the parasite, S. vicaria with the host, Ephydatia fluviatilis is also reported. Some physicochcmical relations of Eunapius fragilis found in the Forest River, North Dakota, are discussed

Preparation, testing, and delivery of low density polyimide foam panels

Plastic foams based on polyimide resins were shown to be stable at relatively high temperatures, and to possess very low flame spread and smoke generation characteristics. A system and process were developed to prepare low-density polyimide foam from a liquid formulation. The system is based on the reaction of micropulverized grade pyromellitic dianhydride with a polymeric diisocyanate. The panels produced were postcured at elevated temperatures to achieve maximum thermal and fire resistance, and incorporation of a fire retardant into the formulation was considered. The effects of a flame retardant (Flameout 5600B1) were investigated, but eliminated in preference to the postcuring approach

<i>Caviziphius altirostris</i>, a new beaked whale from the Miocene southern North Sea basin

An odontocete cranium from Miocene deposits in northern Belgium is examined and referred to Caviziphius altirostris, a new genus and species of beaked whale. In the general architecture of its vertex and closed mesorostral canal, Caviziphius resembles the fossil genera Ziphirostrum and Choneziphius, but differs from all known ziphiids by a very deep excavated prenarial basin with a semicircular outline in lateral view. This peculiar cranial architecture of Caviziphius might indicate an advanced and efficient mechanism of sound production in this fossil ziphiid

Constitutive modelling of Sandvik 1RK91

A physically based constitutive equation is being developed for the maraging\ud stainless steel Sandvik 1RK91. The steel is used to make precision parts. These parts are formed through multistage forming operations and heat treatments from cold rolled and annealed sheets. The specific alloy is designed to be thermodynamically unstable, so that deformation even at room temperatures can bring about a change in the phase of face centred cubic austenite to either hexagonal closed packed martensite and/or, body centred cubic martensite. This solid state phase change is a function of the strain path, strain, strain rate and temperature. Thus, the fraction of the new phase formed depends on the state of stress at a given location in the part being formed. Therefore a set of experiments is being conducted in order to quantify the stress-strain behavior of this steel under various stress states, strain, strain rate as well as temperature. A magnetic sensor records the fraction of ferromagnetic martensite formed from paramagnetic austenite. A thermocouple as well as an infra red thermometer is used to log the change in temperature of the steel during a mechanical test. The force-displacement data are converted to stress-strain data after correcting for the changes in strain rate and temperature. These data are then cast into a general form of constitutive equation and the transformation equations are derived from Olson-Cohen type functions

Middeleeuws Urk onder Wijk 6-6

Het gedurende twee jaar nauwkeurig volgen van graafwerkzaamheden onder de woning Wijk 6-6 in de oude dorpskern van Urk leverde een schat aan archeologische vondsten en waarnemingen op. Duidelijk werd dat op of nabij deze locatie van 1381 tot midden 15de eeuw het befaamde ‘Huze tot Orck’ stond. Een Sterkte die met soldaten, kruisbogen en kerkers de zeeroverij op de vaargeulen langs Urk moest bestrijden. Ook bleek dat er vanaf de 12de eeuw, misschien zelfs al eerder, op deze plek een grote boerderij stond. Die boerderij stond in een vrijwel boomloos landschap en maakte deel uit van een uitgestrekt lint van boerderijen dat langs de noordflank van de bult van Urk liep. De weg die de boerderijen verbond, is te herkennen in de nu nog bestaande Oude Straat van Urk en is de enige nog bestaande en functionerende middeleeuwse straat van Flevoland