Cusp Disruption in Minor Mergers

We present 0.55 x 10^6 particle simulations of the accretion of high-density dwarf galaxies by low-density giant galaxies, using models that contain both power-law central density cusps and point masses representing supermassive black holes. The cusp of the dwarf galaxy is disrupted during the merger, producing a remnant with a central density that is only slightly higher than that of the giant galaxy initially. Removing the black hole from the giant galaxy allows the dwarf galaxy to remain intact and leads to a remnant with a high central density, contrary to what is observed. Our results support the hypothesis that the persistence of low-density cores in giant galaxies is a consequence of supermassive black holes.Comment: 5 pages, 2 postscript figures, uses emulateapj.sty. Accepted for publication in The Astrophysical Journal Letter

Finite-temperature regularization

We present a non-perturbative regularization scheme for Quantum Field Theories which amounts to an embedding of the original unregularized theory into a spacetime with an extra compactified dimension of length L ∼ Λ-1 (with Λ the ultraviolet cutoff), plus a doubling in the number of fields, which satisfy different periodicity conditions and have opposite Grassmann parity. The resulting regularized action may be interpreted, for the fermionic case, as corresponding to a finite-temperature theory with a supersymmetry, which is broken because of the boundary conditions. We test our proposal both in a perturbative calculation (the vacuum polarization graph for a D-dimensional fermionic theory) and in a non-perturbative one (the chiral anomaly).Facultad de Ciencias Exacta

Spatial Analysis of Predator Abundance and Northern Bobwhite Nest Success in Southern Texas

Northern bobwhites (Colinus virginianus) have low nest success across their geographic range, and predation is the primary cause of failure. We evaluated the influence of relative abundance of predators on northern bobwhite nest success. We used data from a long- term radiotelemetry study conducted on 3 sites (800 ha each) in Brooks County, Texas during 2000–2007. We located bobwhite nests (n 1⁄4 456) using radiotelemetry and estimated Mayfield nest success each year. We also estimated relative abundance of nest predators using scent stations (400 3 400 m grid/site) during the nesting season (May–Aug). We developed a gradient map of predator relative abundance and correlated this variable with location-specific bobwhite nest success. Mayfield nest success during the incubation period (23 days) varied between 0.43 and 0.60 during the study. Scent-station visitation rates (% stations visited/night) ranged from 0 to 67%

De sacra scriptura: la palabra de Dios, escuela de oración*

A fundamental dimension of the Word of God is discovering it as a real «School of Prayer» because behind each biblical expression one may found the «silent voice» of a loving father, eager to create again his children to build up communities as a big family. The author unfolds his arguments studying thoroughly the psalm 150, which closes partially the praises in Israel, and leaves an open space to create our owwn psalms as far as our daily life goes on.Una de las dimensiones fundamentales de la Palabra de Dios consiste en descubrirla como una verdadera «Escuela de oración»; pues detrás de cada expresión bíblica, se encuentra la «voz silenciosa» de un papá amoroso, quien busca recrear cada día a sus hijos e hijas para hacer de las comunidades una gran familia. El autor desarrolla estos argumentos estudiando en forma detenida el Salmo 150, el cual entrecierra la puerta de las «Alabanzas» en Israel, pero a la vez deja abierto un espacio para forjar nuestros propios salmos en el trasegar de la historia cotidiana

Intensity prediction model based on machine learning for regional earthquake early warning

Seismic intensity plays a crucial role in influencing the decision-making process of users utilizing earthquake early warning systems (EEWs) upon receiving warning information. Improving intensity warnings’ speed and accuracy is vital. We present a straightforward and dependable model for predicting intensity, which is based only on location and magnitude information. We use the catalog of intensity data from the Japan Meteorological Agency (JMA) released as a dataset, totaling 944,877 intensity instances. To address the issue of imbalanced dataset distribution, we employ the Synthetic Minority Over-Sampling Technique (SMOTE) as a means to improve this situation. Considering the distribution of high intensity data and the importance of features in the model, we construct and jointly apply intensity prediction models for magnitude below 5.7 and above 5.7, respectively. Further, we analyze the robustness of the model by adding random errors for magnitude and location information. We test the transfer capability of the proposed model with four earthquake events in China. Further, we use 466 seismic events (20,542 intensity instances) without published intensity data from the Kyoshin network (K-NET) as the application dataset. We simulate the phenomenon of underestimation of large earthquakes and overestimation of small earthquakes, which is used to analyze the possible application of the proposed model to EEWs. The findings indicate that the model achieves an accuracy of 97.77% when subjected to a magnitude error of 0.3 and a location error of 0.2°. Finally, we analyze the timeliness of the proposed model with a magnitude 7.4 event in 2022.The paper is supported by the National Natural Science Foundation of China 52278313, and Project to Attract Foreign Experts G2023133018L

Analogies between the crossing number and the tangle crossing number

Tanglegrams are special graphs that consist of a pair of rooted binary trees with the same number of leaves, and a perfect matching between the two leaf-sets. These objects are of use in phylogenetics and are represented with straightline drawings where the leaves of the two plane binary trees are on two parallel lines and only the matching edges can cross. The tangle crossing number of a tanglegram is the minimum crossing number over all such drawings and is related to biologically relevant quantities, such as the number of times a parasite switched hosts. Our main results for tanglegrams which parallel known theorems for crossing numbers are as follows. The removal of a single matching edge in a tanglegram with $n$ leaves decreases the tangle crossing number by at most $n-3$, and this is sharp. Additionally, if $\gamma(n)$ is the maximum tangle crossing number of a tanglegram with $n$ leaves, we prove $\frac{1}{2}\binom{n}{2}(1-o(1))\le\gamma(n)<\frac{1}{2}\binom{n}{2}$. Further, we provide an algorithm for computing non-trivial lower bounds on the tangle crossing number in $O(n^4)$ time. This lower bound may be tight, even for tanglegrams with tangle crossing number $\Theta(n^2)$.Comment: 13 pages, 6 figure

Temporal and Spatial Trends of Northern Bobwhite Survival and Nest Success

The northern bobwhite (Colinus virginianus) has been declining in abundance across North America for many years. It is unknown, however, if other population variables also exhibit this downward trajectory. We conducted a retrospective-analysis of annual survival and nest success based on a literature review of 64 studies and compared these estimates temporally and spatially. We hypothesized that increased management efforts influenced bobwhite survival in the 1990s. Evidence from linear splining indicated survival trends changed in 1994. Thus, we compared trends across 3 periods: before 1994, after 1994, and overall. Mean (6 SD) annual survival was 13.9 6 9.4% across 31 studies from 1970 to 2007. Annual survival decreased 0.534% per year during 1970–1994 and stabilized thereafter. This stabilization in survival occurred along latitudinal and longitudinal gradients in which survival decreased at the northern and western periphery of the bobwhite range. Our linear splining models did not support the hypothesis that trends in nest success changed in the 1990s; thus, we only compared trends across the overall, 1924–2008 range of studies. Mean nest success across 33 studies was 44.4 6 15.2% during this interval and increased slightly across the 1924–2008 range of studies. We observed latitudinal gradients in nest success. Nest success was lowest at the northern periphery of the bobwhite range; it decreased 0.90% per degree of latitude. Annual survival stabilized after 1994 despite monotonic declines in bobwhite abundance since at least the 1960s. Range-wide survival and nest success trends may not parallel trends in abundance, particularly after 1990, which suggests biologists may not fully understand the range-wide population ecology of bobwhites. This lends support for the need to monitor other aspects of the bobwhites range-wide population dynamics as supplements to range-wide abundance