La encrucijada de la Vivienda de Interés Social en Bogotá: Los precios del suelo

En este documento se estudia el problema de la vivienda de interés social, VIS, en Bogotá asociada al precio del suelo. Se revisan algunos postulados que han tenido un impacto sobre el problema de manejo del precio del suelo. Se parte de la revisión de la estructura de asentamiento poblacional de la ciudad como evidencia de la desequilibrada ocupación y oferta de bienes urbanos. La perspectiva cuantitativa utilizada indica que la incorporación de suelo urbano no tiene el efecto señalado de bajar los precios. La dinámica de los precios del suelo muestra un comportamiento inercial de estos, derivados de la racionalidad algo ingenua de los propietarios. La asociación con la evolución de la construcción indica que los constructores y su tendencia a capturar rentas de anticipación los lleva a cometer errores si no se preveen los ciclos. A pesar de ser una industria con una organización competitiva existe evidencia de un componente no explicado del precio que puede ser igualmente una renta, en este caso tecnológica. DOI: http://dx.doi.org/10.22518/16578953.729

Diseño Conceptual de un Sistema de Aprovechamiento Pluvial, como Estrategia De Desarrollo Sostenible Para el Comando de Policía de Bucaramanga.

El presente estudio tuvo como fin diseñar mediante las bases de la ingeniería conceptual, un sistema de aprovechamiento de aguas pluviales para el comando de Policía Nacional de Bucaramanga como estrategia de desarrollo sostenible. Para ello, se estableció un desarrollo metodológico de recolección de fuentes de información secundaria de las bases de datos de las estaciones meteorológicas e hidrológicas del Instituto de Meteorología y estudios ambientales IDEAM. Con base en la información obtenida se determinó la oferta hídrica pluvial de Bucaramanga y se diseñó conceptualmente un sistema de aprovechamiento de aguas pluviales adaptado a las condiciones del comando de policía; se calculó la demanda máxima y se realizaron los cálculos para conocer si el sistema de aprovechamiento supliría con la necesidad del comando, acertando en un cubrimiento del 70 % del requerido, razón por la cual, se consideró este un método eficaz para la gestión ambiental de la Policía Nacional. Finalmente, se hizo el análisis costo beneficio del proyecto donde el tiempo de retorno de capital invertido de acuerdo al presupuesto realizado, se cumple en aproximadamente 6 años, el ahorro anual del sistema de captación está por encima de los $6.000.000 de pesos colombianos y aunque el tiempo de retorno es largo, la viabilidad del proyecto es factible en términos ambientales para las condiciones del lugar caso estudio del proyecto.he purpose of this study was to design, through the foundations of conceptual engineering, a rainwater harvesting system for the Bucaramanga national police command as a sustainable development strategy. For this, there is a methodological development of collecting secondary information sources from the databases of meteorological and hydrological stations of the Institute of Meteorology and environmental studies IDEAM. Based on the information obtained, Bucaramanga rainwater supply was determined and a rainwater harvesting system adapted to the conditions of the police command was formulated, a water requirement was calculated in terms of maximum demand of 160 m3 / month and Check the calculations to know if the rainwater harvesting system would meet the need by making a 70Finally, the cost-benefit analysis of the project was carried out where the return time of the capital invested from the agreement to the budget made, is fulfilled in approximately 6 years, the annual savings of the collection system is above$ 6,000,000 Colombian pesos and although the return time is long, the viability of the project is feasible for the conditions of the project case study

Dual-path state reconstruction scheme for propagating quantum microwaves and detector noise tomography

Quantum state reconstruction involves measurement devices that are usually described by idealized models, but not known in full detail in experiments. For weak propagating microwaves, the detection process requires linear amplifiers which obscure the signal with random noise. Here, we introduce a theory which nevertheless allows one to use these devices for measuring all quadrature moments of propagating quantum microwaves based on cross-correlations from a dual-path amplification setup. Simultaneously, the detector noise properties are determined, allowing for tomography. We demonstrate the feasibility of our novel concept by proof-of-principle experiments with classical mixtures of weak coherent microwaves.Comment: 11 pages, 3 figure

Age‐dependent amyloid deposition is associated with white matter alterations in cognitively normal adults during the adult life span

Introduction Both beta‐amyloid (Ab) deposition and decline in white matter integrity, are brain alterations observed in Alzheimer's disease (AD) and start to occur by the fourth and fifth decades. However, the association between both brain alterations in asymptomatic subjects is unclear. Methods Amyloid positron emission tomography (PET) and diffusion tensor imaging (DTI) were obtained in 282 cognitively normal subjects (age 30‐89 years). We assessed the interaction of age by abnormal amyloid PET status (Florbetapir F‐18 PET >1.2 standard uptake value ratio [SUVR]) on regional mean diffusivity (MD) and global white matter hyperintensity (WMH) volume, controlled for sex, education, and hypertension. Results Subjects with abnormal amyloid PET (n = 87) showed stronger age‐related increase in global WMH and regional MD, particularly within the posterior parietal regions of the white matter. Discussion Sporadic Aβ deposition is associated with white matter alterations in AD predilection areas in an age‐dependent manner in cognitively normal individuals

White matter diffusion alterations precede symptom onset in autosomal dominant Alzheimer\u27s disease

White matter alterations are present in the majority of patients with Alzheimer\u27s disease type dementia. However, the spatiotemporal pattern of white matter changes preceding dementia symptoms in Alzheimer\u27s disease remains unclear, largely due to the inherent diagnostic uncertainty in the preclinical phase and increased risk of confounding age-related vascular disease and stroke in late-onset Alzheimer\u27s disease. In early-onset autosomal-dominantly inherited Alzheimer\u27s disease, participants are destined to develop dementia, which provides the opportunity to assess brain changes years before the onset of symptoms, and in the absence of ageing-related vascular disease. Here, we assessed mean diffusivity alterations in the white matter in 64 mutation carriers compared to 45 non-carrier family non-carriers. Using tract-based spatial statistics, we mapped the interaction of mutation status by estimated years from symptom onset on mean diffusivity. For major atlas-derived fibre tracts, we determined the earliest time point at which abnormal mean diffusivity changes in the mutation carriers were detectable. Lastly, we assessed the association between mean diffusivity and cerebrospinal fluid biomarkers of amyloid, tau, phosphorylated-tau, and soluble TREM2, i.e. a marker of microglia activity. Results showed a significant interaction of mutations status by estimated years from symptom onset, i.e. a stronger increase of mean diffusivity, within the posterior parietal and medial frontal white matter in mutation carriers compared with non-carriers. The earliest increase of mean diffusivity was observed in the forceps major, forceps minor and long projecting fibres-many connecting default mode network regions-between 5 to 10 years before estimated symptom onset. Higher mean diffusivity in fibre tracts was associated with lower grey matter volume in the tracts\u27 projection zones. Global mean diffusivity was correlated with lower cerebrospinal fluid levels of amyloid-β1-42 but higher levels of tau, phosphorylated-tau and soluble TREM2. Together, these results suggest that regionally selective white matter degeneration occurs years before the estimated symptom onset. Such white matter alterations are associated with primary Alzheimer\u27s disease pathology and microglia activity in the brain

Electronically Controllable Phase Shifter with Progressive Impedance Transformation at K Band

This communication presents the design of a two-port electronically tunable phase shifter at K band. The phase shifter consists of a 3 dB hybrid coupler loaded with reflective phase-controllable circuits. The reflective circuits are formed by varactors and non-sequential impedance transformers which increase the operational bandwidth and the provided phase shift. The final phase shifter design is formed by two loaded-coupler stages of phase shifting to guarantee a complete phase turn. An 18 GHz phase shifter design with dynamic range of 600 degrees of phase shift is depicted in this document. The prototype is manufactured and validated through measurements showing good agreement with the simulation results.This work has been partially supported by the TIN2016-75097-P, RTI2018-102002-A-I00, and EQC2018- 004988-P projects of the Spanish National Program of Research, Development, and Innovation and project B-TIC-402-UGR18 of Junta de Andalucí

Correspondence Between Resting-State and Episodic Memory-Task Related Networks in Elderly Subjects

Resting-state fMRI studies demonstrated temporally synchronous fluctuations in brain activity among ensembles of brain regions, suggesting the existence of intrinsic functional networks. A spatial match between some of the resting-state networks and regional brain activation during cognitive tasks has been noted, suggesting that resting-state networks support particular cognitive abilities. However, the spatial match and predictive value of any resting-state network and regional brain activation during episodic memory is only poorly understood. In order to address this research gap, we obtained fMRI acquired both during rest and a face-name association task in 38 healthy elderly subjects. In separate independent component analyses, networks of correlated brain activity during rest or the episodic memory task were identified. For the independent components identified for task-based fMRI, the design matrix of successful encoding or retrieval trials was regressed against the time course of each of the component to identify significantly activated networks. Spatial regression was used to assess the match of resting-state networks against those related to successful memory encoding or retrieval. We found that resting-state networks covering the medial temporal, middle temporal, and frontal areas showed increased activity during successful encoding. Resting-state networks located within posterior brain regions showed increased activity during successful recognition. However, the level of resting-state network connectivity was not predictive of the task-related activity in these networks. These results suggest that a circumscribed number of functional networks detectable during rest become engaged during successful episodic memory. However, higher intrinsic connectivity at rest may not translate into higher network expression during episodic memory

The left frontal cortex supports reserve in aging by enhancing functional network efficiency

Background: Recent evidence from fMRI studies suggests that functional hubs, i.e. highly connected brain regions, are important for mental health. We found recently that global connectivity of a hub in the left frontal cortex (LFC-connectivity) is associated with relatively preserved memory abilities and higher levels of protective factors (education, IQ) in normal aging and Alzheimer’s disease. These results suggest that LFC-connectivity supports reserve capacity alleviating memory decline. An open question is, however, why LFC-connectivity is beneficial and supports memory function in the face of neurodegeneration. We hypothesized that higher LFCconnectivity is associated with enhanced efficiency in connected major networks involved in episodic memory. We further hypothesized that higher LFC-related network efficiency predicts higher memory abilities. Methods: We assessed fMRI during a face-name association learning task in 26 healthy cognitively normal elderly participants. Using beta-series correlation analysis, we computed task-related LFC-connectivity to key memory networks including the default-mode network (DMN) and dorsal attention network (DAN). Network efficiency within the DMN and DAN was estimated by the graph theoretical small-worldness statistic. We applied linear regression analyses in order to test the association between LFC-connectivity to the DMN/DAN and small-worldness of these networks. Mediation analysis was applied to test LFC-connectivity to the DMN and DAN as a mediator of the association between education and higher DMN and DAN smallworldness. Lastly, we tested network small-worldness as a predictor of memory performance. Results: We found that higher LFC-connectivity to the DMN and DAN during successful memory encoding and recognition was associated with higher small-worldness of those networks. Higher task-related LFC-connectivity mediated the association between education and higher small-worldness in the DMN and DAN. Further, higher small-worldness of these networks predicted better performance in the memory task. Conclusions: The current results suggest that higher education-related LFC-connectivity to key memory networks during a memory task is associated with higher network efficiency and thus enhanced reserve of memory abilities in aging