Land rents and their impact on the development of Low-cost Affordable Housing (VIS) in Colombia: Case study of Bogotá D.C. (2005 to 2022)

Este documento pretende evidenciar y analizar las posibles relaciones entre las rentas del suelo y algunos aspectos o características del desarrollo de Vivienda de Interés Social VIS en Bogotá D.C., durante el periodo comprendido entre los años 2005 y 2022. Se soporta en el procesamiento de una base de datos que contiene más de tres mil registros de proyectos e inmuebles de viviendas VIS comercializadas en Bogotá, y utilizando de manera conjunta y de retroalimentación sistemas de procesamiento de bases de datos “Data Science”, sistemas estadísticos y de información geográfica GIS, se logra vislumbrar la evolución de los fenómenos sobre el territorio de la ciudad. Respecto de los proyectos, la ubicación, densidad y altura; y respecto de los inmuebles, la cantidad de viviendas, el área, el precio, y cantidad de habitaciones; todo esto en una escala de tiempo anual que permite establecer relaciones entre las variaciones de estas variables y la evolución del precio del suelo, que se obtiene aplicando la metodología del valor residual deductivo para proyectos inmobiliarios de vivienda. Por otro lado, el documento propone una reflexión profunda respecto a que, la gobernanza sobre el territorio establece las condiciones de oferta y demanda de la vivienda social en el país; en relación con la oferta, se expone la formación de las rentas del suelo para hacer entender la formación del precio del suelo; y en relación con la demanda, se realiza una descripción general de los subsidios a la demanda como instrumento principal en las políticas públicas de acceso a la vivienda en Colombia; por lo anterior, se relacionan los gobiernos de turno y se muestran de manera general algunos de los hitos principales a nivel nacional y distrital, para invitar a establecer relaciones temporales con los resultados de los análisis de las variables contempladas.This research aims to shed light on the complex relationship between land rents and the development of Low-cost Affordable Housing (VIS) in Bogotá D.C., Colombia, covering the period from 2005 to 2022. Employing advanced data processing techniques, including Data Science, statistical systems, and Geographic Information Systems (GIS), an extensive database of over three thousand records of commercialized VIS housing projects and properties in Bogotá is analyzed. This integrated approach reveals evolving trends across the city's landscape, considering factors such as project location, density, height, and property attributes such as unit count, area, price, and room configuration. The analysis is conducted on an annual time scale, establishing relationships between variations in these variables and fluctuations in land prices. The deductive residual value methodology designed for residential real estate projects is utilized to obtain land price data. Furthermore, this study provides profound insights into how territorial governance influences the dynamics of supply and demand in the social housing sector in Colombia. The formation of land rents as a crucial driver of land prices is explored, highlighting its impact on low-cost housing affordability. Additionally, an extensive overview of demand-side subsidies is presented as a primary instrument within Colombia's public housing policies. Key milestones at the national and district levels are outlined to provide contextual understanding, emphasizing the significance of successive governments; and by establishing temporal connections between these milestones and the analysis, a comprehensive understanding of the interplay between policy decisions and variables under consideration is achieved.Magíster en Planeación Urbana y RegionalMaestrí

Multiannual infestation patterns of grapevine plant inhabiting Scaphoideus titanus (Hemiptera: Cicadellidae) leafhoppers

The Nearctic leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae) was accidentally introduced in Europe, where it became the vector of the ‘Candidatus Phytoplasma vitis' phytoplasma causing the ‘Flavescence dorée' disease of grapevine plants. A time-varying distributed delay model, simulating the successive occurrences of egg hatching, nymph presence, and adult emergence, is extended here to represent multi-generation infestation patterns of grapevine plants inhabited by eggs, nymphs, and adults. The model extension includes intrinsic mortality, mortality caused by plant dormancy, and low temperatures, development of diapausing and post-diapausing eggs, fecundity rates, and adult longevity. Field observations and published data were used to estimate parameters. The model was validated with five years canopy infestation data from five vineyards not subjected to insecticide treatments and found to have satisfactory explicative and predictive qualities. The model output is most sensitive to a 10% variation in the upper threshold and in the shape parameters of the survivorship function and least sensitive to a 10% variation in the shape parameters of the development function and the survivorship level. Recommendations are made to take into account other factors than temperature and plant phenology and include a wider geographical area in further model developmen

Two-State Migration of DNA in a structured Microchannel

DNA migration in topologically structured microchannels with periodic cavities is investigated experimentally and with Brownian dynamics simulations of a simple bead-spring model. The results are in very good agreement with one another. In particular, the experimentally observed migration order of Lambda- and T2-DNA molecules is reproduced by the simulations. The simulation data indicate that the mobility may depend on the chain length in a nonmonotonic way at high electric fields. This is found to be the signature of a nonequilibrium phase transition between two different migration states, a slow one and a fast one, which can also be observed experimentally under appropriate conditions.Comment: Revised edition corresponding to the comments by the referees, submitted to Physical Review

Phase Transitions of Single Semi-stiff Polymer Chains

We study numerically a lattice model of semiflexible homopolymers with nearest neighbor attraction and energetic preference for straight joints between bonded monomers. For this we use a new algorithm, the "Pruned-Enriched Rosenbluth Method" (PERM). It is very efficient both for relatively open configurations at high temperatures and for compact and frozen-in low-T states. This allows us to study in detail the phase diagram as a function of nn-attraction epsilon and stiffness x. It shows a theta-collapse line with a transition from open coils to molten compact globules (large epsilon) and a freezing transition toward a state with orientational global order (large stiffness x). Qualitatively this is similar to a recently studied mean field theory (Doniach et al. (1996), J. Chem. Phys. 105, 1601), but there are important differences. In contrast to the mean field theory, the theta-temperature increases with stiffness x. The freezing temperature increases even faster, and reaches the theta-line at a finite value of x. For even stiffer chains, the freezing transition takes place directly without the formation of an intermediate globule state. Although being in contrast with mean filed theory, the latter has been conjectured already by Doniach et al. on the basis of low statistics Monte Carlo simulations. Finally, we discuss the relevance of the present model as a very crude model for protein folding.Comment: 11 pages, Latex, 8 figure

Deconstructing Indian cotton: weather, yields, and suicides

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Structural insights into the nucleic acid remodeling mechanisms of the yeast THO-Sub2 complex

The yeast THO complex is recruited to active genes and interacts with the RNA-dependent ATPase Sub2 to facilitate the formation of mature export-competent messenger ribonucleoprotein particles and to prevent the co-transcriptional formation of RNA:DNA-hybrid-containing structures. How THO-containing complexes function at the mechanistic level is unclear. Here, we elucidated a 3.4 angstrom resolution structure of Saccharomyces cerevisiae THO-Sub2 by cryoelectron microscopy. THO subunits Tho2 and Hpr1 intertwine to form a platform that is bound by Mft1, Thp2, and Text. The resulting complex homodimerizes in an asymmetric fashion, with a Sub2 molecule attached to each protomer. The homodimerization interfaces serve as a fulcrum for a seesaw-like movement concomitant with conformational changes of the Sub2 ATPase. The overall structural architecture and topology suggest the molecular mechanisms of nucleic acid remodeling during mRNA biogenesis.We thank Daniel Bollschweiler and Tillman Schäfer at the MPIB cryo-EM facility..

Anomalous Dynamics of Translocation

We study the dynamics of the passage of a polymer through a membrane pore (translocation), focusing on the scaling properties with the number of monomers $N$. The natural coordinate for translocation is the number of monomers on one side of the hole at a given time. Commonly used models which assume Brownian dynamics for this variable predict a mean (unforced) passage time $\tau$ that scales as $N^2$, even in the presence of an entropic barrier. However, the time it takes for a free polymer to diffuse a distance of the order of its radius by Rouse dynamics scales with an exponent larger than 2, and this should provide a lower bound to the translocation time. To resolve this discrepancy, we perform numerical simulations with Rouse dynamics for both phantom (in space dimensions $d=1$ and 2), and self-avoiding (in $d=2$) chains. The results indicate that for large $N$, translocation times scale in the same manner as diffusion times, but with a larger prefactor that depends on the size of the hole. Such scaling implies anomalous dynamics for the translocation process. In particular, the fluctuations in the monomer number at the hole are predicted to be non-diffusive at short times, while the average pulling velocity of the polymer in the presence of a chemical potential difference is predicted to depend on $N$.Comment: 9 pages, 9 figures. Submitted to Physical Review