Auswirkungen differenzierter ökologischer Bewirtschaftung von Ansaat- und Dauergrünland auf Futterangebot, Fressverhalten sowie Weideleistung und Schlachtreife von Ochsen und Färsen

Von 2004 bis 2006 wurde durch die Universität Halle-Wittenberg am ZTT Iden der LLFG Sachsen-Anhalt ein Versuch zur Weidemast von Rindern auf 26 ha extensiv ökologisch bewirtschaftetem Dauergrünland in zwei Düngungsstufen (0 und 70 kg N/ha) durchgeführt. Die jährlich zwei Versuchsherden bestanden aus je circa 30 Absetzern (Ochsen und Färsen) üblicher Gebrauchskreuzungen (2004; tragende HF-Färsen). Der Tierbesatz lag bei max. 1 - 1,4 GV/ha. Die Versuchsflächen (vier Koppeln/Herde) lagen auf drei, bezüglich Bodenart, Feuchtigkeit und Pflanzenbestand, unterschiedlichen Standorten. Die Artenzahl war vom vorhandenen Pflanzenbestand zu Versuchsbeginn abhängig. Ein Flächentyp (Ansaatgrünland, leichter Boden) zeigte sich äußerst problematisch hinsichtlich Pflanzenbestand und Ertrag. Im überständigen Aufwuchs wurden vorwiegend Blattmasse enthaltende Bestandesschichten bevorzugt und Stängel und Blüten verschmäht. Die Energiekonzentrationen und Verdaulichkeiten des aufgenommenen Futters lagen deutlich über denen im Mittel des Futterangebotes, wobei der Unterschied besonders gegen Ende einer Teilflächenbeweidung deutlich wurde. Die Tiere waren in der Lage, durch die Futterselektion sehr lange ein hohes Qualitätsniveau zu halten und somit rückläufige Qualitätsentwicklungen zu einem guten Teil auszugleichen. Die Alkanmethode erwies sich mit der Unterscheidung ledig nach Artengruppen und für Untersuchungen von teils überständigen Pflanzenaufwüchsen zur Ermittlung einer artengruppenspezifischen Futterselektion als ungeeignet. Bezüglich des Tierverhaltens konnten zwischen beiden Herden signifikante, geringfügige Unterschiede festgestellt werden. Die mittleren Lebendmassezunahmen lagen bei über 800g pro Tag und waren hinsichtlich der Düngungsvarianten nicht signifikant unterschiedlich. Die Schlachtkörper sowohl der Ochsen wurden mit U und R (Fleischigkeit) eingestuft. Bei über 80 % der Tiere wurde die angestrebte Fettklasse 3 erzielt

F-monoids

A semigroup $S$ is called $F-monoid$ if $S$ has an identity and if there exists a group congruence $\rho$ on $S$ such that each $\rho$-class of $S$ contains a greatest element with respect to the natural partial order of $S$ (see Mitsch, 1986). Generalizing results given in Giraldes et al. (2004) and specializing some of Giraldes et al. (Submitted) five characterizations of such monoids $S$ are provided. Three unary operations $\star$, $\circ$ and $-$ on $S$ defined by means of the greatest elements in the different $\rho$-classes of $S$ are studied. Using their properties, a charaterization of $F$-monoids $S$ by their regular part $S^\circ=\{a^\circ:a\in S\}$ and the associates of elements in $S^\circ$ is given. Under the hypothesis that $S^\star=\{a^\star:a\in S\}$ is a subsemigroup it is shown that $S$ is regular, whence of a known structure (see Giraldes et al., 2004).Fundação para a Ciência e a Tecnologia (FCT

F −semigroups

A semigroup S is called F−semigroup if there exists a group congruence ρ on S such that every ρ −class contains a greatest element with respect to the natural partial order ≤ of S . This generalizes the concept of F−inverse semigroups introduced by V. Wagner in 1961 and investigated by McFadden and O’Caroll in 1971. Five different characterisations of general F−semigroups S are given: by means of residuals, by special principal anticones, by properties of the set of idempotents, by the maximal elements in (S, ≤) and finally, an axiomatic one using an additional unary operation. Also, F−semigroups in special classes are considered; in particular, inflations of semigroups and strong semi- lattices of monoids are studied.Centro de Matemática da Universidade do MinhoFundação para a Ciência e a Tecnologia (FCT

Generalised F-semigroups

Fundação para a Ciência e a Tecnologia (FCT) - POCTI

Dispersive Optical Interface Based on Nanofiber-Trapped Atoms

We dispersively interface an ensemble of one thousand atoms trapped in the evanescent field surrounding a tapered optical nanofiber. This method relies on the azimuthally-asymmetric coupling of the ensemble with the evanescent field of an off-resonant probe beam, transmitted through the nanofiber. The resulting birefringence and dispersion are significant; we observe a phase shift per atom of $\sim$\,1\,mrad at a detuning of six times the natural linewidth, corresponding to an effective resonant optical density per atom of 0.027. Moreover, we utilize this strong dispersion to non-destructively determine the number of atoms.Comment: 4 pages, 4 figure

F-regular semigroups

A semigroup S is called F-regular if S is regular and if there exists a group congruence rho on S such that every rho-class contains a greatest element with respect to the natural partial order of S (see [K.S. Nambooripad, Proc. Edinburgh Math. Soc. 23 (1980) 249-260]). These semigroups were investigated in [C.C. Edwards, Semigroup Forum 19 (1980) 331-345] where a description similar to the F-inverse case (see [R. McFadden, L. O'Carroll, Proc. London Math. Soc. 22 (1971) 652-666]) is given. Further characterizations of F-regular semigroups, including an axiomatic one, are provided. The main objective is to give a new representation of such semigroups by means of Szendrei triples (see [M. Szendrei, Acta Sci. Math. 51 (1987) 229-249]). The particular case of F-regular semigroups S satisfying the identity (xy)* = y*x*, where x* epsilon S denotes the greatest element of the rho-class containing x epsilon S, is considered. Also the F-inversive semigroups, for which this identity holds, are characterized. (C) 2004 Elsevier Inc. All rights reserved.Fundação para a Ciência e a Tecnologia (FCT) - POCTI

Doppler-free two-photon spectrum of the 000 band of the Ã1B1←X1A1 transition in difluorodiazirine, F2CN2

The Doppler-free two-photon excitation spectrum of the vibrationless Ã1B1←Image 1A1 transition of difluorodiazirine (F2CN2) has been recorded with a resolution of 15 MHz using a cw single-mode dye laser coupled to an external concentric resonator. The asymmetric rotor spectrum has been analysed and more than 350 lines randomly selected from all five branches were assigned in order to fit the ground- and excited-state rotational and quartic centrifugal distortion constants. From the rotational constants the rNN and rFF distances in the ground Image 1A1 and excited Ã1B1 state were determined. The geometry change upon excitation is found to be ΔrNN = 3.89(2) pm and ΔrFF = −4.09(2) pm. No perturbation in the rotational structure of the 000 band has been found. This points to a small singlet-triplet coupling matrix element in the small molecule limit

F–semigroups

A semigroup S is called F- semigroup if there exists a group-congruence ρ on S such that every ρ-class contains a greatest element with respect to the natural partial order ≤S of S (see [8]). This generalizes the concept of F-inverse semigroups introduced by V. Wagner [12] and investigated in [7]. Five different characterizations of general F-semigroups S are given: by means of residuals, by special principal anticones, by properties of the set of idempotents, by the maximal elements in (S,≤S) and finally, an axiomatic one using an additional unary operation. Also F-semigroups in special classes are considered; in particular, inflations of semigroups and strong semilattices of monoids are studied

Asteroseismological Observations of the Central Star of the Planetary Nebula NGC 1501

We report on a global CCD time-series photometric campaign to decode the pulsations of the nucleus of the planetary nebula NGC1501. The star is hot and hydrogen-deficient, similar to the pre-white-dwarf PG 1159 stars. NGC1501 shows pulsational brightness variations of a few percent with periods ranging from 19 to 87 minutes. The variations are very complex, suggesting a pulsation spectrum that requires a long unbroken time series to resolve. Our CCD photometry of the star covers a two-week period in 1991 November, and used a global network of observatories. We obtained nearly continuous coverage over an interval of one week in the middle of the run. We have identified 10 pulsation periods, ranging from 5235 s down to 1154 s. We find strong evidence that the modes are indeed nonradial g-modes. The ratios of the frequencies of the largest-amplitude modes agree with those expected for modes that are trapped by a density discontinuity in the outer layers. We offer a model for the pulsation spectrum that includes a common period spacing of 22.3 s and a rotation period of 1.17 days; the period spacing allows us to assign a seismological mass of 0.55+/-0.03 Msun.Comment: 12 pages, AASTEX, 7 tables, 6 EPS figures, to appear in AJ, 12/96 Corrected version repairs table formatting and adds missing Table