Abuelito

An outsider’s perspective of the Spanish funerary process and the universal grappling with grief

In Defense of Feminists Who Like Fashion

I’m sitting on the downtown R train one night in Manhattan, a copy of Vogue resting on my crossed legs. It is late and I am clearly unwinding peacefully as I thumb through page after glamorous page of my magazine. The train stops at Prince Street and there’s the usual flux of people in and out. Those left inside settle as the train pulls out of the station. “Ugh. Fashion is stupid,” remarks one young man to another, both of whom are sitting diagonally from me and well within earshot. He’s watching me ignore him as I continue enjoying my reading material. [excerpt

Generating sequences and Poincar\'e series for a finite set of plane divisorial valuations

Let $V$ be a finite set of divisorial valuations centered at a 2-dimensional regular local ring $R$. In this paper we study its structure by means of the semigroup of values, $S_V$, and the multi-index graded algebra defined by $V$, \gr_V R. We prove that $S_V$ is finitely generated and we compute its minimal set of generators following the study of reduced curve singularities. Moreover, we prove a unique decomposition theorem for the elements of the semigroup. The comparison between valuations in $V$, the approximation of a reduced plane curve singularity $C$ by families of sets $V^{(k)}$ of divisorial valuations, and the relationship between the value semigroup of $C$ and the semigroups of the sets $V^{(k)}$, allow us to obtain the (finite) minimal generating sequences for $C$ as well as for $V$. We also analyze the structure of the homogeneous components of \gr_V R. The study of their dimensions allows us to relate the Poincar\'e series for $V$ and for a general curve $C$ of $V$. Since the last series coincides with the Alexander polynomial of the singularity, we can deduce a formula of A'Campo type for the Poincar\'e series of $V$. Moreover, the Poincar\'e series of $C$ could be seen as the limit of the series of $V^{(k)}$, $k\ge 0$

Small-world behavior in a system of mobile elements

We analyze the propagation of activity in a system of mobile automata. A number r L^d of elements move as random walkers on a lattice of dimension d, while with a small probability p they can jump to any empty site in the system. We show that this system behaves as a Dynamic Small-World (DSW) and present analytic and numerical results for several quantities. Our analysis shows that the persistence time T* (equivalent to the persistence size L* of small-world networks) scales as T* ~ (r p)^(-t), with t = 1/(d+1).Comment: To appear in Europhysics Letter

The stellar content of the Local Group dwarf galaxy Phoenix

We present new deep $VI$ ground-based photometry of the Local Group dwarf galaxy Phoenix. Our results confirm that this galaxy is mainly dominated by red stars, with some blue plume stars indicating recent (100 Myr old) star formation in the central part of the galaxy. We have performed an analysis of the structural parameters of Phoenix based on an ESO/SRC scanned plate, in order to search for differentiated component. The results were then used to obtain the color-magnitude diagrams for three different regions of Phoenix in order to study the variation of the properties of its stellar population. The young population located in the central component of Phoenix shows a clear asymmetry in its distribution, that could indicate a propagation of star formation across the central component. The HI cloud found at 6 arcmin Southwest by Young & Lo (1997) could have been involved in this process. We also find the presence of a substantial intermediate-age population in the central region of Phoenix that would be less abundant or absent in its outer regions. This result is also consistent with the gradient found in the number of horizontal branch stars, whose frequency relative to red giant branch stars increases towards the outer part of the galaxy. These results, together with those of our morphological study, suggest the existence of an old, metal-poor population with a spheroidal distribution surrounding the younger inner component of Phoenix. This two-component structure may resemble the halo-disk structure observed in spirals, although more data, in particular on kinematics, are necessary to confirm this.Comment: 46 pages, 21 figures, 9 Tables, to be published in AJ, August 9

Spin dynamics of current driven single magnetic adatoms and molecules

A scanning tunneling microscope can probe the inelastic spin excitations of a single magnetic atom in a surface via spin-flip assisted tunneling in which transport electrons exchange spin and energy with the atomic spin. If the inelastic transport time, defined as the average time elapsed between two inelastic spin flip events, is shorter than the atom spin relaxation time, the STM current can drive the spin out of equilibrium. Here we model this process using rate equations and a model Hamiltonian that describes successfully spin flip assisted tunneling experiments, including a single Mn atom, a Mn dimer and Fe Phthalocyanine molecules. When the STM current is not spin polarized, the non-equilibrium spin dynamics of the magnetic atom results in non-monotonic $dI/dV$ curves. In the case of spin polarized STM current, the spin orientation of the magnetic atom can be controlled parallel or anti-parallel to the magnetic moment of the tip. Thus, spin polarized STM tips can be used both to probe and to control the magnetic moment of a single atom.Comment: 15 pages, 12 figure