A Density Spike on Astrophysical Scales from an N-Field Waterfall Transition

Hybrid inflation models are especially interesting as they lead to a spike in the density power spectrum on small scales, compared to the CMB, while also satisfying current bounds on tensor modes. Here we study hybrid inflation with $N$ waterfall fields sharing a global $SO(N)$ symmetry. The inclusion of many waterfall fields has the obvious advantage of avoiding topologically stable defects for $N>3$. We find that it also has another advantage: it is easier to engineer models that can simultaneously (i) be compatible with constraints on the primordial spectral index, which tends to otherwise disfavor hybrid models, and (ii) produce a spike on astrophysically large length scales. The latter may have significant consequences, possibly seeding the formation of astrophysically large black holes. We calculate correlation functions of the time-delay, a measure of density perturbations, produced by the waterfall fields, as a convergent power series in both $1/N$ and the field's correlation function $\Delta(x)$. We show that for large $N$, the two-point function is $\,\propto\Delta^2(|{\bf x}|)/N$ and the three-point function is $<\delta t({\bf x})\,\delta t({\bf y})\,\delta t({\bf 0})>\,\propto\Delta(|{\bf x}-{\bf y}|)\Delta(|{\bf x}|)\Delta(|{\bf y}|)/N^2$. In accordance with the central limit theorem, the density perturbations on the scale of the spike are Gaussian for large $N$ and non-Gaussian for small $N$.Comment: 15 pages in double column format, 6 figures. V2: Further clarifications, updated to coincide with version published in Physics Letters

Esparsette (Onobrychis viciifolia) als mögliche Futterpflanze zur Kontrolle von Magen-Darm-Strongyliden bei Schafen

In der Schaf- und Ziegenhaltung stellt der Befall mit Magen-Darm-Strongyliden (MDS) einen wesentlichen Problemfaktor für die Tiergesundheit dar. Klinische und subklinische Erkrankungen können von erheblicher wirtschaftlicher Relevanz sein. Eine zunehmende Resistenzentwicklung gegen seit langem eingesetzte Anthelminthika hat derzeit einen intensivierten Einsatz dieser Wirkstoffe zur Folge und verschärft das Problem somit zusätzlich. Die Entwicklung und Bereitstellung komplementärer Kontrollstrategien könnte zu einer erheblichen Reduktion des Anthelminthika-Einsatzes beitragen. Eine mögliche Strategie stellt der Einsatz tanninhaltiger Futterpflanzen dar. Wir beschreiben Ergebnisse aus einem in vivo Versuch zur antiparasitischen Wirkung von Esparsettenheu und Esparsettensilage (6,2 % und 4,4 % Tannine / Trockensubstanz) gegen Haemonchus contortus und Cooperia curticei in experimentell infizierten Lämmern. Nach 16-tägiger Fütterung mit Esparsettenheu war die H. contortus Wurmbürde im Vergleich zu einer isoproteisch und isoenergetisch gefütterten Kontrollgruppe (0,1 % Tannine / Trockensubstanz) um 53 % reduziert (P < 0,05). Es konnte gezeigt werden, dass Lämmer, die mit Esparsettenheu gefüttert wurden, bereits 10 Tage nach Versuchsbeginn 44 % (P < 0,05) weniger H. contortus Eier pro Gramm Kot (EpG) ausschieden als die Kontrolltiere. Bei Versuchsende (16 Tage nach Fütterungsbeginn) war die H. contortus Eiausscheidung im Vergleich zur Kontrolle um 58 % reduziert (P < 0,01). Die Tagesgewichtszunahme der Lämmer in der Esparsettenheu-Gruppe war im Vergleich zur Kontrollgruppe tendenziell besser (163 g/Tag und 96 g/Tag; P = 0,07). Die Fütterung mit Esparsettensilage reduzierte die H. contortus Eiausscheidung verglichen mit der Kontrolle um 48 %. Dieses Resultat war allerdings nicht signifikant (P = 0,075). Im Vergleich zu den Kontrollgruppen wurde die C. curticei Eiausscheidung durch Esparsettenheu um 74 % (P < 0,001) und durch Esparsettensilage um 81 % (P < 0,001) reduziert. Es handelt sich bei dieser Studie um die erste, welche die für den Praxiseinsatz wichtige Verwendung einer konservierten, tanninhaltigen Futterpflanze gezielt gegen H. contortus und C. curticei untersucht

A high-reflectivity high-Q micromechanical Bragg-mirror

We report on the fabrication and characterization of a micromechanical oscillator consisting only of a free-standing dielectric Bragg mirror with high optical reflectivity and high mechanical quality. The fabrication technique is a hybrid approach involving laser ablation and dry etching. The mirror has a reflectivity of 99.6%, a mass of 400ng, and a mechanical quality factor Q of approximately 10^4. Using this micromirror in a Fabry Perot cavity, a finesse of 500 has been achieved. This is an important step towards designing tunable high-Q high-finesse cavities on chip.Comment: 3 pages, 2 figure

Effects of paddock management on vegetation, nutrient accumulation, and internal parasites in laying hens

Management of paddocks for free-range layers requires an effort from farmers to minimize the adverse effects of these systems on animal health (e.g., parasites) and environment (e.g., nutrient accumulation and leaching). In this study, we report results from 2 on-farm experiments conducted to investigate (1) the effects of rotational versus continuous use of the paddocks and (2) the effects of wood chips in the area close to the pop holes (openings to the paddock) with regard to turf quality, nutrient load in the soil, and parasite infections. Rotational use of the hen paddocks led to a lower proportion of bare soil close to the house, but not in more distant regions. Covering the area in front of the house with wood chips did not reduce bare areas. Nitrogen and phosphorous contents in soil were similar in permanently and rotationally used paddocks; they were usually higher close to the house than in distant regions. Neither nutrient accumulated over the observation period. There was no significant effect of the 2 management regimens on worm burdens (Ascaridia galli, Heterakis gallinarum, Capillaria spp.) at the end of the laying period. Fecal egg counts were significantly reduced on rotationally used paddocks and (in 3 of 4 cases) on paddocks with wood chips in the area close to the pop holes compared with unmanaged paddocks. Based on the positive effects on turf quality, manageability, and helminth egg excretion, we recommend rotational paddock management and a permanently used, small all-weather run covered with wood chips or gravel for free-range layer flock

Self-cooling of a micro-mirror by radiation pressure

We demonstrate passive feedback cooling of a mechanical resonator based on radiation pressure forces and assisted by photothermal forces in a high-finesse optical cavity. The resonator is a free-standing high-reflectance micro-mirror (of mass m=400ng and mechanical quality factor Q=10^4) that is used as back-mirror in a detuned Fabry-Perot cavity of optical finesse F=500. We observe an increased damping in the dynamics of the mechanical oscillator by a factor of 30 and a corresponding cooling of the oscillator modes below 10 K starting from room temperature. This effect is an important ingredient for recently proposed schemes to prepare quantum entanglement of macroscopic mechanical oscillators.Comment: 11 pages, 9 figures, minor correction

Magnetic field generation in Higgs inflation model

We study the generation of magnetic field in Higgs-inflation models where the Standard Model Higgs boson has a large coupling to the Ricci scalar. We couple the Higgs field to the Electromagnetic fields via a non- renormalizable dimension six operator suppressed by the Planck scale in the Jordan frame. We show that during Higgs inflation magnetic fields with present value $10^{-6}$ Gauss and comoving coherence length of $100 kpc$ can be generated in the Einstein frame. The problem of large back-reaction which is generic in the usual inflation models of magneto-genesis is avoided as the back-reaction is suppressed by the large Higgs-curvature coupling.Comment: 10 pages, RevTeX

Absolute and convective instabilities of parallel propagating circularly polarized Alfven waves: Beat instability

Ruderman and Simpson [Phys. Plasmas 11, 4178 (2004)] studied the absolute and convective decay instabilities of parallel propagating circularly polarized Alfven waves in plasmas where the sound speed c(S) is smaller than the Alfven speed upsilon(A). We extend their analysis for the beat instability which occurs in plasmas with c(S)>upsilon(A). We assume that the dimensionless amplitude of the circularly polarized Alfven wave (pump wave), a, is small. Applying Briggs' method we study the problem analytically using expansions in power series with respect to a. It is shown that the pump wave is absolutely unstable in a reference frame moving with the velocity U with respect to the rest plasma if U-lU-r, the instability is convective. The signaling problem is studied in a reference frame where the pump wave is convectively unstable. It is shown that the spatially amplifying waves exist only when the signaling frequency is in two narrow symmetric frequency bands with the widths of the order of a(3). These results enable us to extend for the case when c(S)>upsilon(A) the conclusions, previously made for the case when c(S)<upsilon(A), that circularly polarized Alfven waves propagating in the solar wind are convectively unstable in a reference frame of any spacecraft moving with the velocity not exceeding a few tens of km/s in the solar reference frame. The characteristic scale of spatial amplification for these waves exceeds 1 a.u

Diversity in the Tail of the Intersecting Brane Landscape

Techniques are developed for exploring the complete space of intersecting brane models on an orientifold. The classification of all solutions for the widely-studied T^6/Z_2 x Z_2 orientifold is made possible by computing all combinations of branes with negative tadpole contributions. This provides the necessary information to systematically and efficiently identify all models in this class with specific characteristics. In particular, all ways in which a desired group G can be realized by a system of intersecting branes can be enumerated in polynomial time. We identify all distinct brane realizations of the gauge groups SU(3) x SU(2) and SU(3) x SU(2) x U(1) which can be embedded in any model which is compatible with the tadpole and SUSY constraints. We compute the distribution of the number of generations of "quarks" and find that 3 is neither suppressed nor particularly enhanced compared to other odd generation numbers. The overall distribution of models is found to have a long tail. Despite disproportionate suppression of models in the tail by K-theory constraints, the tail in the distribution contains much of the diversity of low-energy physics structure.Comment: 48 pages, 8 figure

Tanniferous forage plants: Agronomic performance, palatability and efficacy against parasitic nematodes in sheep

Tanniferous forage plants can have beneficial effects on ruminant productivity and health (improved protein supply, bloat safety and antiparasitic properties). However, condensed tannins can also lower palatability, voluntary feed intake and digestibility. The aim of our interdisciplinary project was to generate basic knowledge on plant management, feed palatability and the antiparasitic properties of tanniferous forage plants for their practical application in agronomy, focusing on their usefulness in controlling gastrointestinal nematodes in organic farming. We found that Onobrychis viciifolia (sainfoin), Lotus corniculatus (birdsfoot trefoil) and Cichorium intybus (chicory) were suitable for cultivation under the given temperate climatic conditions, whereas Lotus pedunculatus (big trefoil) was soon outcompeted by unsown species. Growing the tanniferous plant species in a mixture with Festuca pratensis (meadow fescue) rather than in a monoculture had the advantage of increasing total dry matter (DM) yield (especially in the case of tanniferous legumes) and of reducing the DM proportions of unsown species. However, due to dilution by non-tanniferous F. pratensis, the tannin concentrations of mixtures were clearly lower and the seasonal fluctuations in tannin concentrations greater than that of monocultures. Across species, tannin concentrations were highest for O. viciifolia, followed by L. corniculatus and very low for C. intybus. Palatability of all tanniferous forages was comparable to that of a ryegrass/clover mixture when fed as dried forage and, when offered as silage, palatability of O. viciifolia was clearly superior to that of the respective ryegrass/clover control. Administration of dried or ensiled O. viciifolia reduced parasite egg counts in feces of lambs co-infected with the gastrointestinal nematode species Haemonchus contortus and Cooperia curticei. We conclude that O. viciifolia is the most promising among the tested tanniferous forage plant species due to its suitability for cultivation, its high tannin concentration, its high palatability and its antiparasitic activity even in dried or ensiled for