Generalized Ribaucour-type surfaces

In this work we generalize the surfaces studied in [8], we define the generalization of Ribaucour-type surfaces (in short, GRT-surfaces). We obtain present a representation for GRT-surfaces with prescribed Gauss map which depends on two holomorphic functions and a real function l. We give explicit examples of GRT-surfaces. Also, we use this representation to classify the GRT-surfaces of rotation.Comment: arXiv admin note: substantial text overlap with arXiv:2303.0322

Determinación de calidad del agua mediante variables fisicoquímicas y las comunidades de macroinvertebrados bentónicos presentes en el Río Chonta

RESUMEN El presente trabajo de investigación se realizó en base a un análisis integrado en la cuenca del río Chonta, ubicada en los distritos de Baños del Inca y La Encañada, provincia de Cajamarca, en Perú. Enmarcado en el uso de comunidades de macroinvertebrados bentónicos como indicadores biológicos, junto a la evaluación de parámetros fisicoquímicos en el cauce principal de esta cuenca (Río Chonta), ya que durante la última década ha sido afectada por actividades antrópicas debido al vertimiento de aguas residuales sin previo tratamiento. Para evaluar la condición ambiental del río Chonta se establecieron dos temporalidades de estudio (Temporada Húmeda y en Estiaje), analizando 22 variables ambientales (en cada temporada) y la fauna bentónica fue recolectada haciendo uso del método cualitativo (identificación de organismos hasta el nivel taxonómico de familia), con la técnica de colecta mediante la red D-net. Para estudiar la relación entre las comunidades de macroinvertebrados y las variables fisicoquímicas se realizaron distintos análisis estadísticos, como fue la regresión lineal. Así también, las variables ambientales fueron comparadas con los Estándares de Calidad Ambiental para Agua Categoría 3 (Categorizada por Autoridad Nacional del Agua del Perú) y se usó el Índice BMWP/Col para asignar valores cuantitativos a las comunidades de macroinvertebrados bentónicos, en este sentido, se identificaron mediante una regresión lineal, los parámetros que más afectan la comunidad bentónica. Los resultados que se obtuvieron indicaron que la distribución y composición bentónica es determinada por la variación de los parámetros fisicoquímicos definido por la degradación ambiental. Se concluyó que las metodologías aplicadas para el estudio río Chonta fueron apropiadas para determinar su calidad de agua, la cual se encontró en un rango de moderadamente contaminadas en los seis puntos de muestreo para temporada húmeda y cuatro primeros puntos para temporada de estiaje, y presentando aguas contaminadas en los dos últimos puntos de la temporada de estiaje; lo cual indica una mayor intervención antrópica a medida que el cauce del río se acerca a las urbes, donde existe mayor actividad industrial y evidencia el inadecuado manejo de los recursos hídricos.ABSTRACT The present research work was carried out based on an integrated analysis in the Chonta River basin, located in the districts of Baños del Inca and La Encañada, province of Cajamarca, in Peru. Framed in the use of communities of benthic macroinvertebrates as biological indicators, together with the evaluation of physicochemical parameters in the main channel of this basin (Chonta River), since during the last decade it has been affected by anthropic activities due to the dumping of wastewater without previous treatment. To assess the environmental condition of the Chonta River, two temporalities of study were established (Wet Season and Estuary), analyzing 22 environmental variables (in each season) and the benthic fauna was collected using the qualitative method (identification of organisms up to the taxonomic level). of family), with the collection technique through the D-net network. In order to study the relationship between the macroinvertebrate communities and the physicochemical variables, different statistical analyzes were carried out. Likewise, the environmental variables were compared with the Environmental Quality Standards for Water Category 3 (Categorized by the National Water Authority of Peru) and the BMWP / Col Index was used to assign quantitative values to the communities of benthic macroinvertebrates, in this sense, the parameters that most affect the benthic community were identified through a linear regression. The results that were obtained indicated that the distribution and benthic composition is determined by the variation of the physicochemical parameters defined by the environmental degradation. It was concluded that the methodologies applied for the study of the Chonta river were appropriate to determine its water quality, which was found in a range of moderately polluted in the six sampling points for the wet season and four first points for the dry season, and presenting contaminated water in the last two points of the dry season; which indicates a greater anthropic intervention as the river bed approaches the cities, where there is greater industrial activity and evidences the inadequate management of water resources

Enforcing Morphological Information in Fully Convolutional Networks to Improve Cell Instance Segmentation in Fluorescence Microscopy Images

Cell instance segmentation in fluorescence microscopy images is becoming essential for cancer dynamics and prognosis. Data extracted from cancer dynamics allows to understand and accurately model different metabolic processes such as proliferation. This enables customized and more precise cancer treatments. However, accurate cell instance segmentation, necessary for further cell tracking and behavior analysis, is still challenging in scenarios with high cell concentration and overlapping edges. Within this framework, we propose a novel cell instance segmentation approach based on the well-known U-Net architecture. To enforce the learning of morphological information per pixel, a deep distance transformer (DDT) acts as a back-bone model. The DDT output is subsequently used to train a top-model. The following top-models are considered: a three-class (\emph{e.g.,} foreground, background and cell border) U-net, and a watershed transform. The obtained results suggest a performance boost over traditional U-Net architectures. This opens an interesting research line around the idea of injecting morphological information into a fully convolutional model.Comment: Accepted at the IWANN 2021 (International Work-Conference on Artificial and Natural Neural Networks

Comparing hysteretic energy and ductility uniform annual failure rate spectra for traditional and a spectral shape-based intensity measure

In this study, with the objective to develop a reliability-based seismic design tool, ductility and dissipated hysteretic energy uniform annual failure rate (UAFR) spectra are obtained and compared using the spectral acceleration at first mode of vibration of the structure Sa(T1) and the well-known spectral shape-based intensity measure INp. Notice that this is the first time in the literature that UAFR spectra are obtained for the advanced spectral shape intensity measure INp. For this aim, 110 simulated ground motions recorded from the soft soil of Mexico City were selected due to their large energy amount demanded to the structures; moreover, four elastoplastic hysteretic behavior models are considered for the dynamic analyses with post-yielding stiffness of 0, 3, 5, and 10%. It is observed that the use of elasto-perfectly plastic models provided similar UAFR spectra in comparison with hysteretic models with different post-yielding stiffness. This conclusion is valid for the two selected intensity measures. In addition, the lateral resistance required to achieve similar structural reliability levels is larger when the INp intensity measure is used, especially for buildings with vibration periods equal or larger than the soil period, in such a way that the traditional use of Sa(T1) could provide structures with less structural reliability levels.Peer ReviewedPostprint (published version

Multi-Wavelength View of Kiloparsec-Scale Clumps in Star-Forming Galaxies at z~2

This paper studies the properties of kiloparsec-scale clumps in star-forming galaxies at z~2 through multi-wavelength broad band photometry. A sample of 40 clumps is identified through auto-detection and visual inspection from 10 galaxies with 1.5<z<2.5 in the Hubble Ultra Deep Field, where deep and high-resolution HST/WFC3 and ACS images enable us to resolve structures of z~2 galaxies down to kpc scale in the rest-frame UV and optical bands as well as to detect clumps toward the faint end. The physical properties of clumps are measured through fitting spatially resolved seven-band (BVizYJH) spectral energy distribution to models. On average, the clumps are blue and have similar median rest-frame UV--optical color as the diffuse components of their host galaxies, but the clumps have large scatter in their colors. Although the star formation rate (SFR)--stellar mass relation of galaxies is dominated by the diffuse components, clumps emerge as regions with enhanced specific SFRs, contributing individually ~10% and together ~50% of the SFR of the host galaxies. However, the contributions of clumps to the rest-frame UV/optical luminosity and stellar mass are smaller, typically a few percent individually and ~20% together. On average, clumps are younger by 0.2 dex and denser by a factor of 8 than diffuse components. Clump properties have obvious radial variations in the sense that central clumps are redder, older, more extincted, denser, and less active on forming stars than outskirts clumps. Our results are broadly consistent with a widely held view that clumps are formed through gravitational instability in gas-rich turbulent disks and would eventually migrate toward galactic centers and coalesce into bulges. Roughly 40% of the galaxies in our sample contain a massive clump that could be identified as a proto-bulge, which seems qualitatively consistent with such a bulge-formation scenario.Comment: Accepted by ApJ. This updated version matches the in-press one. 50 pages (single column), 10 figures, 3 table

Investigating potential planetary nebula/cluster pairs

Fundamental parameters characterizing the end-state of intermediate-mass stars may be constrained by discovering planetary nebulae (PNe) in open clusters (OCs). Cluster membership may be exploited to establish the distance, luminosity, age, and physical size for PNe, and the intrinsic luminosity and mass of its central star. Four potential PN-OC associations were investigated, to assess the cluster membership for the PNe. Radial velocities were measured from intermediate-resolution optical spectra, complemented with previous estimates in the literature. When the radial velocity study supported the PN/OC association, we analyzed if other parameters (e.g., age, distance, reddening, central star brightness) were consistent with this conclusion. Our measurements imply that the PNe VBe3 and HeFa1 are not members of the OCs NGC5999 and NGC6067, respectively, and likely belong to the background bulge population. Conversely, consistent radial velocities indicate that NGC2452/NGC2453 could be associated, but our results are not conclusive and additional observations are warranted. Finally, we demonstrate that all the available information point to He2-86 being a young, highly internally obscured PN member of NGC4463. New near-infrared photometry acquired via the Vista Variables in the Via Lactea ESO public survey was used in tandem with existing UBV photometry to measure the distance, reddening, and age of NGC4463, finding d=1.55+-0.10 kpc, E(B-V)=0.41+-0.02, and tau=65+-10 Myr, respectively. The same values should be adopted for the PN if the proposed cluster membership will be confirmed.Comment: Accepted for publication in A&

Global economic crisis and corruption

© 2014, Springer Science+Business Media New York. We study the effects of the 2008–2009 global economic crisis on the household experience of bribing public officials. The data come from the Life in Transition-2 survey, conducted in 2010 in 30 post-socialist economies of Central and Eastern Europe and Central Asia. We find that households hit by crisis are more likely to bribe and, among people who bribe, crisis victims bribe a wider range of public officials than non-victims. The crisis victims are also more likely to pay bribes because public officials ask them to do so and less likely because of gratitude. The link between crisis and bribery is stronger in the poorest countries of the region. Our findings support the conjecture that public officials misuse sensitive information about crisis victims to inform bribe extortion decisions

CANDELS: The progenitors of compact quiescent galaxies at z~2

We combine high-resolution HST/WFC3 images with multi-wavelength photometry to track the evolution of structure and activity of massive (log(M*) > 10) galaxies at redshifts z = 1.4 - 3 in two fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS). We detect compact, star-forming galaxies (cSFGs) whose number densities, masses, sizes, and star formation rates qualify them as likely progenitors of compact, quiescent, massive galaxies (cQGs) at z = 1.5 - 3. At z > 2 most cSFGs have specific star-formation rates (sSFR = 10^-9 yr^-1) half that of typical, massive SFGs at the same epoch, and host X-ray luminous AGN 30 times (~30%) more frequently. These properties suggest that cSFGs are formed by gas-rich processes (mergers or disk-instabilities) that induce a compact starburst and feed an AGN, which, in turn, quench the star formation on dynamical timescales (few 10^8 yr). The cSFGs are continuously being formed at z = 2 - 3 and fade to cQGs by z = 1.5. After this epoch, cSFGs are rare, thereby truncating the formation of new cQGs. Meanwhile, down to z = 1, existing cQGs continue to enlarge to match local QGs in size, while less-gas-rich mergers and other secular mechanisms shepherd (larger) SFGs as later arrivals to the red sequence. In summary, we propose two evolutionary scenarios of QG formation: an early (z > 2), fast-formation path of rapidly-quenched cSFGs that evolve into cQGs that later enlarge within the quiescent phase, and a slow, late-arrival (z < 2) path for SFGs to form QGs without passing through a compact state.Comment: Submitted to the Astrophysical Journal Letters, 6 pages, 4 figure