Persistent massive attractors of smooth maps

For a smooth manifold of any dimension greater than one, we present an open set of smooth endomorphisms such that any of them has a transitive attractor with a non-empty interior. These maps are $m$-fold non-branched coverings, $m \ge 3$. The construction applies to any manifold of the form $S^1 \times M$, where $S^1$ is the standard circle and $M$ is an arbitrary manifold.Comment: 13 pages. Added more references, updated existing one

Modeling the growth dynamics of four candidate crops for Controlled Ecological Life Support Systems (CELSS)

The production of food for human life support for advanced space missions will require the management of many different crops. The research to design these food production capabilities along with the waste management to recycle human metabolic wastes and inedible plant components are parts of Controlled Ecological Life Support Systems (CELSS). Since complete operating CELSS were not yet built, a useful adjunct to the research developing the various pieces of a CELSS are system simulation models that can examine what is currently known about the possible assembly of subsystems into a full CELSS. The growth dynamics of four crops (wheat, soybeans, potatoes, and lettuce) are examined for their general similarities and differences within the context of their important effects upon the dynamics of the gases, liquids, and solids in the CELSS. Data for the four crops currently under active research in the CELSS program using high-production hydroponics are presented. Two differential equations are developed and applied to the general characteristics of each crop growth pattern. Model parameters are determined by closely approximating each crop's data

Split stator vane row for fans and compressors

Operating noise of fans is reduced by adding part span vanes to vane row of stator, reducing the number of full span vanes and maintaining a vane-to-blade ratio of about 2 to 1

Organ Quality as a Complicating Factor in Proposed Systems of Inducements for Organ Donation

En typisk funktion på startsidan till många webbportaler är den webbdel som presenterar exempelvis desenaste blogginläggen, nyheterna eller händelserna som har lagts till på webbplatsen. Dessa funktioner ärkända som aggreggeringswebbdelar. Eftersom startsidan är den sida som besöks mest jämfört med alla andrawebbsidor i portalen innebär det i sin tur att denna funktion utnyttjas väldigt ofta.Detta arbete syftar till att finna ett antal olika metoder som kan användas för att uppnå denna funktion ochatt ta reda på hur väl dessa webbdelar presterar.Denna rapport presenterar både de olika metoder som fanns och resultaten på en systematisk testning avdessa. Resultaten av testerna presenteras på ett överskådligt sätt.Slutligen dras slutsatser angående resultaten. Resultaten förespråkar inte en specifik metod, den metod somlämpar sig bäst för varje enskild sammanhang avgörs till största del av andra faktorer såsom frekvens avbesökare eller ändringar på innehållet som metoden söker igenom

Traintrack Calabi-Yaus from Twistor Geometry

We describe the geometry of the leading singularity locus of the traintrack integral family directly in momentum twistor space. For the two-loop case, known as the elliptic double box, the leading singularity locus is a genus one curve, which we obtain as an intersection of two quadrics in $\mathbb{P}^{3}$. At three loops, we obtain a K3 surface which arises as a branched surface over two genus-one curves in $\mathbb{P}^{1} \times \mathbb{P}^{1}$. We present an analysis of its properties. We also discuss the geometry at higher loops and the supersymmetrization of the construction.Comment: 23 pages, 5 figure

The curiously warped mean plane of the Kuiper belt

We measured the mean plane of the Kuiper belt as a function of semi-major axis. For the classical Kuiper belt as a whole (the non-resonant objects in the semi-major axis range 42--48~au), we find a mean plane of inclination $i_m=1.8^{\circ}$$^{+0.7^{\circ}}_{-0.4^{\circ}}$ and longitude of ascending node $\Omega_m=77^{\circ}$$^{+18^{\circ}}_{-14^{\circ}}$ (in the J2000 ecliptic-equinox coordinate system), in accord with theoretical expectations of the secular effects of the known planets. With finer semi-major axis bins, we detect a statistically significant warp in the mean plane near semi-major axes 40--42~au. Linear secular theory predicts a warp near this location due to the $\nu_{18}$ nodal secular resonance, however the measured mean plane for the 40.3-42~au semi-major axis bin (just outside the $\nu_{18}$) is inclined $\sim13^{\circ}$ to the predicted plane, a nearly 3-$\sigma$ discrepancy. For the more distant Kuiper belt objects of semi-major axes in the range 50--80~au, the expected mean plane is close to the invariable plane of the solar system, but the measured mean plane deviates greatly from this: it has inclination $i_m=9.1^{\circ}$$^{+6.6^{\circ}}_{-3.8^{\circ}}$ and longitude of ascending node $\Omega_m=227^{\circ}$$^{+18^{\circ}}_{-44^{\circ}}$. We estimate this deviation from the expected mean plane to be statistically significant at the $\sim97-99\%$ confidence level. We discuss several possible explanations for this deviation, including the possibility that a relatively close-in ($a\lesssim100$~au), unseen small planetary-mass object in the outer solar system is responsible for the warping.Comment: This version corrects an error in Figure 7 and typographical errors in some equations in Appendix D (changes accepted as an erratum in AJ