Aharonov-Bohm oscillations in the local density of states

The scattering of electrons with inhomogeneities produces modulations in the local density of states of a metal. We show that electron interference contributions to these modulations are affected by the magnetic field via the Aharonov-Bohm effect. This can be exploited in a simple STM setup that serves as an Aharonov-Bohm interferometer at the nanometer scale.Comment: 4 pages, 2 figures. v2 added reference

Quasi-normal mode analysis in BEC acoustic black holes

We perform a quasi-normal mode analysis of black hole configurations in Bose-Einstein condensates (BEC). In this analysis we use the full Bogoliubov dispersion relation, not just the hydrodynamic or geometric approximation. We restrict our attention to one-dimensional flows in BEC with step-like discontinuities. For this case we show that in the hydrodynamic approximation quasi-normal modes do not exist. The full dispersion relation, however, allows the existence of quasi-normal modes. Remarkably, the spectrum of these modes is not discrete but continuous.Comment: 7 pages, 3 figure

Bioclimatology, structure, and conservation perspectives of Quercus pyrenaica, Acer opalus subsp. Granatensis, and Corylus avellana deciduous forests on Mediterranean bioclimate in the South-Central part of the Iberian Peninsula

The plant variability in the southern Iberian Peninsula consists of around 3500 different taxa due to its high bioclimatic, geographic, and geological diversity. The deciduous forests in the southern Iberian Peninsula are located in regions with topographies and specific bioclimatic conditions that allow for the survival of taxa that are typical of cooler and wetter bioclimatic regions and therefore represent the relict evidence of colder and more humid paleoclimatic conditions. The floristic composition of 421 samples of deciduous forests in the south-central part of the Iberian Peninsula were analyzed. The ecological importance index (IVI) was calculated, where the most important tree species were Quercuspyrenaica, Aceropalus subsp. Granatensis, and Corylusavellana. These species are uncommon in the south-central part of the Iberian Peninsula, forming forests of little extension. An analysis of the vertical distribution of the species (stratum) shows that the majority of the species of stratum 3 (hemicriptophics, camephytes, geophites, and nanophanerophytes) are characteristic of deciduous forests, and their presence is positively correlated with high values of bioclimatic variables related to humidity and presence of water in the soil (nemoral environments), while they are negatively correlated with high values of bioclimatic variables related to high temperatures, evapotranspiration, and aridity. This work demonstrates that several characteristic deciduous forest taxa are more vulnerable to disappearance due to the loss of their nemoral conditions caused by gaps in the tree or shrub canopy. These gaps lead to an increase in evapotranspiration, excess insolation, and a consequent loss of water and humidity in the microclimatic conditions.info:eu-repo/semantics/publishedVersio

HOW DO FIRST-YEAR DOMINICAN STUDENTS PERCEIVE THEIR FIRST YEAR OF COLLEGE AND HOW DO THESE PERCEPTIONS IMPACT THEIR RETENTION

College completion rate is a major challenge afflicting colleges and universities as well as students in the United States, particularly Hispanic students (Field, 2018). This qualitative case study aimed to investigate how Dominican students perceived their first year of college and how that perception impacted their retention in a community college in the Northeast. Participants included a purposeful sample of fourteen students (four students enrolled fall of 2021 and four students who did not enroll in the spring of 2022, five students from a focus group, and one of the students from the focus group was interviewed for an in-depth one-on-one interview). In addition, two instructors from the SSD Course (New Student Orientation) and two staff members from the First Year Experience Committee were also interviewed to understand the topic being investigated through multiple perspectives. The students were selected from a Freshman Orientation course administered to first-year students called SSD 100, which operated as a learning community. Students self-identified as Dominican by having at least one Dominican parent. Dominican students were described as a first- generation Dominican (individuals who were born in the Dominican Republic (D.R.) or second-generation Dominican (individuals who were born in the United States (U.S.) The researcher conducted virtual semi-structured individual interviews and focus groups. The findings from this study contributed to the gap in the literature on the retention of Dominican students

Stability analysis of sonic horizons in Bose-Einstein condensates

We examine the linear stability of various configurations in Bose-Einstein condensates with sonic horizons. These configurations are chosen in analogy with gravitational systems with a black hole horizon, a white hole horizon and a combination of both. We discuss the role of different boundary conditions in this stability analysis, paying special attention to their meaning in gravitational terms. We highlight that the stability of a given configuration, not only depends on its specific geometry, but especially on these boundary conditions. Under boundary conditions directly extrapolated from those in standard General Relativity, black hole configurations, white hole configurations and the combination of both into a black hole--white hole configuration are shown to be stable. However, we show that under other (less stringent) boundary conditions, configurations with a single black hole horizon remain stable, whereas white hole and black hole--white hole configurations develop instabilities associated to the presence of the sonic horizons.Comment: 14 pages, 7 figures (reduced resolution

WHAT CAN SCARABAEOIDEA CONTRIBUTE TO THE KNOWLEDGE OF THE BIOGEOGRAPHY OF GUATEMALA?

Scarabaeoidea is one of the biogeographically best known groups of organisms for Nuclear Central America, especially Guatemala. They have been used to determine areas of endemism for cloud forests of the region and to analyze relationships among these endemic areas. A major north-south division of these areas is described. Lowland scenarios are also given. This information was used for justifying the establishment of biological reserves in the area and is a tool available for prioritization of reserve establishment that could be adapted to other parts of the world as well. Scarabaeoidea es uno de los grupos mejor conocidos biogeograficamente en Centroamerica Nuclear, especialmente Guatemala. Han sido usados para establecer areas de endemismo en bosques nubosos de la region y para analizar relaciones entre esas areas. Una division mayor norte-sur de estas areas endemicas esta descrita. Escenarios de tierra de baja elevaci6n tambien se presentan. Esta informacion fue usada para justificar el establecimiento de reservas biologicas en el area y como una valiosa herramienta para priorizar el establecimiento de reservas, lo cual podria ser adaptado tambien a otras partes del mundo