Hot Spaghetti: Viscous Gravitational Collapse

We explore the fate of matter falling into a macroscopic Schwarzschild black hole for the simplified case of a radially collapsing thin spherical shell for which the back reaction of the geometry can be neglected. We treat the internal dynamics of the infalling matter in the framework of viscous relativistic hydrodynamics and calculate how the internal temperature of the collapsing matter evolves as it falls toward the Schwarzschild singularity. We find that viscous hydrodynamics fails when either, the dissipative radial pressure exceeds the thermal pressure and the total radial pressure becomes negative, or the time scale of variation of the tidal forces acting on the collapsing matter becomes shorter than the characteristic hydrodynamic response time.Comment: Invited talk presented at the FIAS International Symposion on Discoveries at the Frontiers of Science - Dedicated to the memory of Walter Greine

Precipitating Ordered Skyrmion Lattices from Helical Spaghetti

Magnetic skyrmions have been the focus of intense research due to their potential applications in ultra-high density data and logic technologies, as well as for the unique physics arising from their antisymmetric exchange term and topological protections. In this work we prepare a chiral jammed state in chemically disordered (Fe, Co)Si consisting of a combination of randomly-oriented magnetic helices, labyrinth domains, rotationally disordered skyrmion lattices and/or isolated skyrmions. Using small angle neutron scattering, (SANS) we demonstrate a symmetry-breaking magnetic field sequence which disentangles the jammed state, resulting in an ordered, oriented skyrmion lattice. The same field sequence was performed on a sample of powdered Cu2OSeO3 and again yields an ordered, oriented skyrmion lattice, despite relatively non-interacting nature of the grains. Micromagnetic simulations confirm the promotion of a preferred skyrmion lattice orientation after field treatment, independent of the initial configuration, suggesting this effect may be universally applicable. Energetics extracted from the simulations suggest that approaching a magnetic hard axis causes the moments to diverge away from the magnetic field, increasing the Dzyaloshinskii-Moriya energy, followed subsequently by a lattice re-orientation. The ability to facilitate an emergent ordered magnetic lattice with long-range orientation in a variety of materials despite overwhelming internal disorder enables the study of skyrmions even in imperfect powdered or polycrystalline systems and greatly improves the ability to rapidly screen candidate skyrmion materials

Evaluation of the capability of local helioseismology to discern between monolithic and spaghetti sunspot models

The helioseismic properties of the wave scattering generated by monolithic and spaghetti sunspots are analyzed by means of numerical simulations. In these computations, an incident f or p1 mode travels through the sunspot model, which produces absorption and phase shift of the waves. The scattering is studied by inspecting the wavefield, computing travel-time shifts, and performing Fourier-Hankel analysis. The comparison between the results obtained for both sunspot models reveals that the differences in the absorption coefficient can be detected above noise level. The spaghetti model produces an steep increase of the phase shift with the degree of the mode at short wavelengths, while mode-mixing is more efficient for the monolithic model. These results provide a clue for what to look for in solar observations to discern the constitution of sunspots between the proposed monolithic and spaghetti models.Comment: Accepted for publication in The Astrophysical Journa

Effects of processing variables and full fat soy flour on nutritional and sensory properties of spaghetti using a mixture design approach.

The influence of full-fat soy flour (FFSF) and extrusion conditions on nutritional and sensory characteristics of spaghetti was evaluated using a mixture design, in order to produce functional pasta. Addition of FFSF increases the nutritional composition significantly (P<or=0.05). Generally, the presence of FFSF showed a negative influence on the color attribute, but no effect on the firmness and surface condition of spaghetti. No significant difference was observed in the beany flavor up to 23.0 g/100 g. The temperature and screw speed of the extruder had no significant effect on nutritional and sensory attributes, but both enhanced the effect of formulation on the color and surface condition of spaghetti. Also, interaction between the screw speed and the ingredients resulted in a slight positive effect on the firmness and beany flavor attributes. Optimum nutritional value and sensory attributes of spaghetti were produced when 17.0 g/100 g FFSF was added and processed at a screw speed of 40 rpm and a temperature of 70 degrees C

Adding Sweeteners to Softwood Lumber: The WTO-NAFTA “Spaghetti Bowl” Is Cooking

With the Doha round in trouble, the so-called spaghetti bowl of multilateral trade rules and proliferating regional trade deals, is, once again, prominently on the radar screen of the international trade community. Perfect examples of this image are the longstanding US-Canada softwood lumber and US-Mexico sweetener disputes. Both trade spats, extensively litigated in NAFTA and the WTO, are close to reaching a climax. Fueling the suspense is that the WTO and NAFTA may reach different results