Exploring quantum quasicrystal patterns: a variational study

We study the emergence of quasicrystal configurations produced purely by quantum fluctuations in the ground-state phase diagram of interacting bosonic systems. By using a variational mean-field approach, we determine the relevant features of the pair interaction potential that stabilize such quasicrystalline states in two dimensions. Unlike their classical counterpart, in which the interplay between only two wave vectors determines the resulting symmetries of the solutions, the quantum picture relates in a more complex way to the instabilities of the excitation spectrum. Moreover, the quantum quasicrystal patterns are found to emerge as the ground state with no need of moderate thermal fluctuations. The study extends to the exploration of the excitation properties and the possible existence of super-quasicrystals, i.e. supersolid-like quasicrystalline states in which the long-range non-periodic density profile coexist with a non-zero superfluid fraction. Our calculations show that, in an intermediate region between the homogeneous superfluid and the normal quasicrystal phases, these exotic states indeed exist at zero temperature. Comparison with full numerical simulations provides a solid verification of the variational approach adopted in this work.Comment: 10 pages, 6 Figure

Wannier-Stark ladders in one-dimensional elastic systems

The optical analogues of Bloch oscillations and their associated Wannier-Stark ladders have been recently analyzed. In this paper we propose an elastic realization of these ladders, employing for this purpose the torsional vibrations of specially designed one-dimensional elastic systems. We have measured, for the first time, the ladder wave amplitudes, which are not directly accessible either in the quantum mechanical or optical cases. The wave amplitudes are spatially localized and coincide rather well with theoretically predicted amplitudes. The rods we analyze can be used to localize different frequencies in different parts of the elastic systems and viceversa.Comment: 10 pages, 6 figures, accepted in Phys. Rev. Let

Sensitivity of Empirical Equation Parameters for the Calculation of Time of Concentration in Urbanized Watersheds

settingsOrder Article Reprints Open AccessArticle Sensitivity of Empirical Equation Parameters for the Calculation of Time of Concentration in Urbanized Watersheds by Jamilton Echeverri-Díaz 1,Óscar E. Coronado-Hernández 2,*ORCID,Gustavo Gatica 3ORCID,Rodrigo Linfati 4ORCID,Rafael D. Méndez-Anillo 2 andJairo R. Coronado-Hernández 5ORCID 1 Departamento de Recursos Hídricos, Sertet SAS, Montería 230002, Colombia 2 Facultad de Ingeniería, Universidad Tecnológica de Bolívar, Cartagena 131001, Colombia 3 Faculty of Engineering—CIS, Universidad Andres Bello, Santiago de Chile 7500971, Chile 4 Department of Industrial Engineering, Universidad del Bío-Bío, Concepción 4030000, Chile 5 Departamento de Productividad e Innovación, Universidad de la Costa, Barranquilla 080001, Colombia * Author to whom correspondence should be addressed. Water 2022, 14(18), 2847; https://doi.org/10.3390/w14182847 Received: 17 August 2022 / Revised: 5 September 2022 / Accepted: 9 September 2022 / Published: 13 September 2022 (This article belongs to the Section Urban Water Management) Download Browse Figures Review Reports Versions Notes Abstract The time of concentration is the time it takes a drop of water in a basin to travel from the most distant point to the outlet, and is one of the most important parameters, along with the morphometric characteristics, for determining the design flow rate in rainfall-runoff models. This study aims to determine the sensitivity of the parameters included in different equations for the calculation of the time of concentration. A case study was conducted on small, urbanized watersheds in the city of Montería, Colombia. The study uses information obtained through field work using GPS equipment and electronic total station, supplemented by geographic information contained in the city drawings of the local sewage company, which includes data on elevations above sea level with sub-metric precision. The time of concentration determined by the 12 empirical equations was compared to the results obtained from the equation proposed by the Natural Resources Conservation Service (NRCS), which was considered as a baseline formulation for the intricacy of calculation. Based on this comparison, it was found that the Carter equation is the one that best fits the results obtained from the NRCS equation because it displayed highly significant goodness of fit values. Even though the equations by Kirpich, Ventura, California Culvert Practice, Simas-Hawkins and TxDOT provide a relatively good fit compared to other empirical equations, they tend to over-estimate time of concentration values, which could lead to the under-estimation of the design flow rates. For this reason, sensitivity analysis of the parameters of these equations represents an alternative for improving the calculation of the time of concentration. The current research analyses deepen the influence of some parameters in the estimation of time of concentration. The research can also be used by designers and engineers in the city of Montería, Colombia, as an important reference to compute time of concentrations in urbanized watersheds

Calidad térmica a través de un gradiente altitudinal para una comunidad de lagartijas en la sierra del Ajusco y el Pedregal de San Ángel, México

ResumenSe evaluó y comparó la calidad térmica del hábitat para una comunidad de lagartijas (9 especies) en un gradiente altitudinal (2 320-3 530 m) en la sierra del Ajusco y Pedregal de San Ángel para determinar si los ambientes térmicos diferentes pueden definir límites de distribución y termorregulación. Se seleccionaron 6 sitios diferentes en altitud y tipo de vegetación para monitorear la temperatura operativa ambiental. Se calculó la calidad térmica mediante la desviación de la temperatura operativa con respecto al intervalo de temperaturas seleccionadas por las lagartijas. Los resultados sugieren 3 tendencias: 1) la temperatura operativa y calidad térmica fueron más altas en los sitios más bajos (2 320 y 2 540 m) con matorral xerófilo; 2) los valores más bajos fueron registrados en los sitios con cobertura vegetal densa con bosque de pino (2 870 y 3 220 m); 3) las zonas abiertas (3 000 y 3 530 m) de pastizal alpino tuvieron valores medios de temperatura operativa y calidad. Estos resultados sugieren que la altitud y el tipo de vegetación tienen influencia en la calidad térmica y los trabajos sobre ecología térmica deben realizarse en varias escalas espaciales para entender los factores involucrados en el nicho térmico y en la termorregulación.AbstractWe evaluated and compared the thermal quality for a lizard community (9 species) in Sierra del Ajusco and Pedregal de San Ángel (central Mexico) along an altitudinal gradient (2 320-3 530 m) to determine whether different thermal environments may be influencing species distribution and thermoregulatory behavior. Six areas that differ in elevation and vegetation type are chosen to survey environmental operative temperatures. Habitat thermal quality is estimated from the mean deviation of operative temperatures from lizards’ selected thermal range. Results indicate 3 key findings: 1) operative temperature and thermal quality are higher at lower elevations (2 320 and 2 540 m), where xeric scrub vegetation was abundant; 2) thermal quality is lowest in closed-canopy pine forest (2 870 and 3 220 m); and 3) intermediate values of operative temperature and thermal quality are observed in open grassland habitat (3 000 and 3 530 m). These results support our hypothesis that elevation and vegetation type affect thermal quality and we conclude that thermal ecology studies should be conducted at multiple spatial scales to gain a better understanding of factors influencing the thermal niche and thermoregulatory profiles

Termorregulación de dos poblaciones de lagartijas simpátridas: Sceloporus lineolateralis y Sceloporus poinsettii (Squamata: Phrynosomatidae) en Durango, México

ResumenLa temperatura ambiental es un factor importante en la regulación de la actividad y los procesos fisiológicos de los organismos ectotermos. Las especies que habitan en simpatría están expuestas a un nicho térmico similar y aquellas especies que están cercanamente emparentadas pueden presentar requerimientos térmicos similares. En el presente trabajo, se estudió la ecología térmica de 2 poblaciones de lagartijas vivíparas, Sceloporus lineolateralis y S. poinsettii, pertenecientes a los grupos Sceloporus torquatus y Sceloporus poinsettii, las cuales habitan en simpatría en la localidad de Peñón Blanco, Durango, México. Las temperaturas corporales de las lagartijas activas en campo y el intervalo de temperaturas corporales preferidas fueron similares entre ambas especies; sin embargo, S. poinsettii registró mayor eficiencia y precisión en la termorregulación, debido a que el intervalo de temperaturas preferidas de esta especie es más amplio. Finalmente, las preferencias térmicas fueron análogas a las registradas anteriormente para los grupos S. torquatus, S. poinsettii y para otras especies del género.AbstractEnvironmental temperature is an important factor that regulates activity and physiological processes of ectotherms. Because sympatric species are exposed to similar thermal niche conditions, closely related species could present similar thermal requirements. This similarity may generate interspecific competition for optimal thermal space. The thermal ecology of the sympatric viviparous lizards Sceloporus lineolateralis and S. poinsettii (Sceloporus torquatus and Sceloporus poinsettii groups, respectively) were studied in natural populations in Peñón Blanco, Durango, Mexico. We found that active body temperatures and selected body temperatures were similar among species. However, S. poinsettii exhibited higher efficiency and accuracy of thermoregulation because the preferred thermal range of this species was wider. Finally their thermal preferences are analogous to those previously reported for the both groups and the genus

BioDR : semantic indexing networks for biomedical document retrieval

In Biomedical research, retrieving documents that match an interesting query is a task performed quite frequently. Typically, the set of obtained results is extensive containing many non-interesting documents and consists in a flat list, i.e., not organized or indexed in any way. This work proposes BioDR, a novel approach that allows the semantic indexing of the results of a query, by identifying relevant terms in the documents. These terms emerge from a process of Named Entity Recognition that annotates occurrences of biological terms (e.g. genes or proteins) in abstracts or full-texts. The system is based on a learning process that builds an Enhanced Instance Retrieval Network (EIRN) from a set of manually classified documents, regarding their relevance to a given problem. The resulting EIRN implements the semantic indexing of documents and terms, allowing for enhanced navigation and visualization tools, as well as the assessment of relevance for new documents.Fundação para a Ciência e a Tecnologia (FCT)Maria Barbeito” contract XuntaHUELLA financed by the Consellería de Sanidade (Xunta de Galicia de Galicia

SpamHunting: An instance-based reasoning system for spam labelling and filtering

n this paper we show an instance-based reasoning e-mail filtering model that outperforms classical machine learning techniques and other successful lazy learners approaches in the domain of anti-spam filtering. The architecture of the learning-based anti-spam filter is based on a tuneable en-hanced instance retrieval network able to accurately generalize e-mail representations. The reuse of similar messages is carried out by a simple unanimous voting mechanism to determine whether the tar-get case is spam or not. Previous to the final response of the system, the revision stage is only performed when the assigned class is spam whereby the system employs general knowledge in the form of meta-rules

Applying lazy learning algorithms to tackle concept drift in spam filtering

A great amount of machine learning techniques have been applied to problems where data is collected over an extended period of time. However, the disadvantage with many real-world applications is that the distribution underlying the data is likely to change over time. In these situations, a problem that many global eager learners face is their inability to adapt to local concept drift. Concept drift in spam is particularly difficult as the spammers actively change the nature of their messages to elude spam filters. Algorithms that track concept drift must be able to identify a change in the target concept (spam or legitimate e-mails) without direct knowledge of the underlying shift in distribution. In this paper we show how a previously successful instance-based reasoning e-mail filtering model can be improved in order to better track concept drift in spam domain. Our proposal is based on the definition of two complementary techniques able to select both terms and e-mails representative of the current situation. The enhanced system is evaluated against other well-known successful lazy learning approaches in two scenarios, all within a cost-sensitive framework. The results obtained from the experiments carried out are very promising and back up the idea that instance-based reasoning systems can offer a number of advantages tackling concept drift in dynamic problems, as in the case of the anti-spam filtering domain