High-frequency properties of thin amorphous ribbons

Magnetic energy losses have been investigated in Co-based near-zero-magnetostriction amorphous ribbons from DC to 10 MHz. Attention has been devoted to the properties of field-annealed ribbons thinned down to 5.8 μm and their behavior at high frequencies. A rationale is provided for the frequency dependence of the magnetic losses over the investigated many-decade range through analysis of the loss components. Ribbons annealed under transverse field benefit by limited irreversible domain wall activity and correspondingly reduced hysteresis and excess losses. Based on the near-linear response of the material and the permeability–energy loss relationship, the separate contributions of domain wall displacements and rotations to the magnetization process and the related dissipation effects are singled out at all frequencies. Very thin amorphous ribbons are shown to display lower loss and higher permeability (i.e. higher Snoek's product) than Mn–Zn ferrites at all frequencies.     

Optimisation of poly-beta-hydroxyalkanoate analysis using gas chromatography for enhanced biological phosphorus removal systems

Poly-beta-hydroxyalkanoate (PHA) is a polymer commonly used in carbon and energy storage for many different bacterial cells. Polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), store PHA anaerobically through metabolism of carbon substrates such as acetate and propionate. Although poly-beta-hydroxybutyrate (PHB) and poly-beta-hydroxyvalerate (PHV) are commonly quantified using a previously developed gas chromatography (GC) method, poly-beta-hydroxy-2-methylvalerate (PH2MV) is seldom quantified despite the fact that it has been shown to be a key PHA fraction produced when PAOs or GAOs metabolise propionate. This paper presents two GC-based methods modified for extraction and quantification of PHB, PHV and PH2MV from enhanced biological phosphorus removal (EBPR) systems. For the extraction of PHB and PHV from acetate fed PAO and GAO cultures, a 3% sulfuric acid concentration and a 2-20 h digestion time is recommended, while a 10% sulfuric acid solution digested for 20h is recommended for PHV and PH2MV analysis from propionate fed EBPR systems.     

Measurement of the\sum {^ - \to ne^ - \bar v} rate and search for ΔQ=−ΔS transitions in Σ+→ne + ν decay

In a bubble chamber experiment about 2×10⁶ Σ ^±-decays have been measured to separateΣ ^±→ne^±¯ν events from the two-body modes. NoΣ ⁺ →ne ⁺ ν event was found whereas 607Σ ^?→ne^?¯ν decays could be identified. The data yield for the ΔQ=?ΔS decay an upper limit: $$\frac{{\Gamma \left( {\sum {^ + } \to ne^ + v} \right)}}{{\Gamma \left( {\sum {^ - } \to ne^ - v} \right)}}< 1.9 x 10^{ - 2} (90\% confidence level)$$ and the branching ratio: $$\frac{{\Gamma \left( {\sum {^ - } \to ne^ - v} \right)}}{{\Gamma \left( {\sum {^ - } \to n\pi ^ - } \right)}} = (1.09 \pm 0.06) x 10^{ - 3} .$$      

Two-particle rapidity correlations in 205 GeV/c pp interactions

Using data obtained from an exposure of the 30-inch bubble chamber at NAL, inclusive and semi-inclusive two-particle rapidity correlations are analyzed for charged-charged, ??, ++, and ± particles. For the inclusive sample, positive correlations are observed in the central region. In the semi-inclusive case, the four-and six-prong events exhibit strong positive correlations near 90° CM. Selection of four-prong events with a large rapidity gap shows that the strong correlation seems to be associated with diffractive-type events.     

Remarks on an s-wave Kπ resonance at 1360 MeV

The $\text{K}{}^{\mathrm{O}}\text{π}{}^{\mathrm{?}}\text{and K}{}^{\mathrm{?}}\text{π}{}^{\mathrm{+}}$ mass distributions obtained from a K^?p experiment at 5.5 GeV/c are used to study the recent suggestion of an s-wave Kπ resonance at 1360 MeV. Using a model including $\text{I =}\text{3}\text{2}$ s- and p- wave and $\text{I =}\text{1}\text{2}$, s-, p- and d-wave amplitudes, we analyze the spherical harmonic moments 〈Y_l⁰〉 of the Kπ decay angular distribution in the K¹ (1420) mass region and obtain the result that the reported mass of 1360 MeV does not necessarily represent the resonance position and is influenced by cuts made in the Kπ decay angle.     

Quantentheorie der Zeitmessung

As a consequence of its dynamical motion a quantum mechanical system may be considered as a quantum mechanical clock. If one demands that the time be an observable which corresponds to a hypermaximal time operator in Hilbert space, then, for systems having a continuous energy spectrum with a lower limit, in the framework of the nonrelativistic theory to be discussed here there must exist an upper limit of energy, too. Furthermore the time operator is not defined on the whole Hilbert space, but only on state functions satisfying a certain condition. Therefrom it results that a quantum mechanical clock of this kind can be read off only in a sequence of equidistant times separated by a “minimal time”. The beginning of the time measurement being arbitrary the scale of time may be shifted according to the homogenity in time. Especially for a free particle beside the minimal time also a minimal length is obtained. The equidistant scale in space is not absolute either, but permits an arbitrary choice of the point of reference according to homogenity in space. The modificated spreading of the probability distribution of particle position is discussed.     

Measurement of the axial-vector to vector coupling constant, ¦g 1/f 1¦, in Σ−→ne − \bar v decay

The ratio of the axial-vector to vector coupling constant, ¦g ₁/f ₁¦, in theΣ ^?→ne ^? \(\bar v\) decay was determined from the electron-neutrino angular distribution. In a sample of 454Σ ^?→ne ^? \(\bar v\) decays a search was made for subsequent neutron proton scattering in order to detect the decay neutrons. TheΣ hyperons were produced by stoppingK ^?-mesons in the 81 cm Saclay hydrogen bubble chamber. For the kinematical analysis 33Σ ^?→ne ^? ν events with associatednp→np interactions were accepted. The value ¦g ₁/f ₁¦=0.37 _?0.19 ^+0.26 was obtained.     

Erzeugung neuer isomerer Kernzustände durch Kernphotoreaktionen am Antimon und Thallium

The systematic search for new short-lived isomeric states has been continued by irradiation of an additional 32 selected elements with 26 MeV bremsstrahlung. Isomeric transitions were detected using a conventional scintillation spectrometer. Irradiation of antimony led to the production of a new (530±50) μsec isomeric state which decays through emission of partially converted (62±2) keV and (76±3) keV gamma rays. The 530 μsec half-life is tentatively associated with the 136 keV level in Sb¹²². An apparent inconsistency in the previously proposed level scheme of Sb¹²² can be removed if the 3.5 min Sb¹²²-activity is assigned to an isomeric level in Sb¹²² lying less than 15 keV above the 136 keV isomeric state. A new measurement of the half-life of this level yielded a value of (4.1₅±0.2) min. Another new isomeric state with a (2.l±0.2) msec half-life was produced by irradiating thallium. The isomeric state decays by emission of two gamma rays of (335±8) keV and (597±12) keV which were found to be in coincidence. Irradiation of erbium led to the production of a short-lived isomeric transition which may be identical with a previously reported Ho-isomer. Results are discussed in the appendix.     

Colon cancer risk factors from nutrition

Nutrition and health are closely connected and malnutrition can seriously endanger health. The consequences are higher risks of developing diseases. Of these, cancers are of special importance. The most frequent nutrition-associated type of cancer is colon cancer. This review summarises the predisposing factors for the development of colon cancer, and molecular mechanisms responsible for sporadic colon cancer. Moreover, it is pointed out that individual genetic predisposition such as polymorphisms of biotransformation systems might affect susceptibility to cancer risk factors. Selected findings of epidemiological research and nutritional habits, foods, and metabolites that could increase cancer risk are discussed. Furthermore, toxicological assessment of food-related risk factors, e.g. heterocyclic amines, and potential protective effects of food ingredients, e.g. the induction of phase II enzymes or removal of already degenerated cells from tissue by apoptosis, inhibition of proliferation, and cell differentiation are discussed. Risks are not necessarily reduced by avoiding certain substances but by healthy and well-balanced nutrition. Knowledge of individual susceptibility will also make it possible to recognise risks and design more specific nutritional recommendations.