100 research outputs found
Open source environment to define constraints in route planning for GIS-T
Route planning for transportation systems is strongly related to shortest path algorithms, an optimization problem extensively studied in the literature. To find the shortest path in a network one usually assigns weights to each branch to represent the difficulty of taking such branch. The weights construct a linear preference function ordering the variety of alternatives from the most to the least attractive.Postprint (published version
Study on behavioral impedance for route planning techniques from the pedestrian's perspective: some findings and considerations
The multi-disciplinary characteristics of transportation force
a new design of geographic information systems, within which
these characteristics are considered. In this context, geographic
information systems for transportation are the result of the
integration of transportation information systems and conventional
geographic information systems. An interesting research area
in geographic information systems for transportation is constraint
management in route planning algorithms from the pedestrian s
perspective. Constraint management becomes more complex when
route planning takes into account an integrated public transportation
network (i.e. a multimodal network). A study on the theoretical
contextualization and taxonomy of a pedestrian s behavioral
impedance has been developed in order to improve the constraint
management from the pedestrian s perspective. This study entails
strategies of travel reduction by private transport (e.g. travel
by car) through switching to or substitution by alternative
public transport (e.g. travel by walk, bus or rail). The
grounded theory method has been used to develop the proposed
taxonomy. Using the partial results of a questionnaire applied
to a reduced group of people from Barcelona as a starting
point, important data are being collected to define the mathematical
model of the behavioral impedance domain. The goal of this
paper is to provide some considerations about theoretical contextualization
on identification and management of constraints regarding the
behavioral impedance domain from the pedestrian s perspective
within the urban public transportation context. The research
project where this work is included is composed of six major
phases. The first phase represents a continuous bibliographic
review. The second phase was a study on sidewalks in the university
zone of Barcelona. In this phase, an experimental application
has been proposed and the management, map and route modules
have been implemented on the ArcInfo GIS package and C++. This
paper reports the partial work of the third phase, which is
composed of two parts. The first part was a theoretical study on
behavioral impedance for route planning techniques, in which
taxonomy was proposed. The results of the second part are partially
presented in this paper. The fourth (i.e. design and implementation),
fifth (i.e. calibration and validation) and sixth (i.e. generalization
of the results) phases are characterized by the application
of the prototype regarding the multimodal network model for
urban public transportation from the pedestrian s perspective.
The main contribution of this article is the behavioral impedance
taxonomy review from the pedestrian s perspective, which will allow
designing a mathematical model and be used to implement a constraint
management algorithm. Within this context, the proposed taxonomy
could be used to model cost functions more precisely.Postprint (published version
Study on behavioral impedance for route planning techniques from the pedestrian's perspective: Part I - Theoretical contextualization and taxonomy
The interest of researchers for analyzing of best routes and shortest
paths allows a continuous technological advance in topological analysis
techniques used in the geographic information systems for
transportation. One of the topological analysis techniques is the route
planning, in which the constraint management must be considered. There
have been few studies where the constraint domain for pedestrian in an
urban transportation system was clearly stated. Consequently, more
studies need to be carried out. The aim of this paper is to provide a
theoretical contextualization on identification and management of
constraints to ascertain the behavioral impedance domain from the
pedestrian perspective. In this part of the research the grounded theory
was the research method used to develop the proposed theory. A
meta-model was used to (1) define the behavioral domain structure, (2)
hold the behavioral data collection and (3) verify the design of the
proposed taxonomic tree. The main contribution of this article is the
behavioral domain taxonomy from the pedestrian perspective, which will
be used to implement a module responsible for the constraint management
of an experimental application, named Router. Within this context, the
proposed taxonomy could be used to model cost functions more precisely.Postprint (published version
Study on k-shortest paths with behavioral impedance domain from the intermodal public transportation system perspective
Behavioral impedance domain consists of a theory on route planning for pedestrians, within which constraint management is considered. The goal of this paper is to present the k-shortest path model using the behavioral impedance approach. After the mathematical model building, optimization problem and resolution problem by a behavioral impedance algorithm, it is discussed how behavioral impedance cost function is embedded in the k-shortest path model. From the pedestrian's route planning perspective, the behavioral impedance cost function could be used to calculate best subjective paths in the objective way.Postprint (published version
Study on behavioral impedance for route planning techniques from the pedestrian s perspective: Part II - Mathematical approach
The theoretical foundations of the behavioral impedance domain are based
on (1) a meta-model composed of analytical and mathematical approaches
and (2) a taxonomy on the constraints involved in the decision-making
process of a pedestrian during the route selection.
The goal of this technical report is to present the mathematical model
of the behavioral impedance domain. The partial least squares approach
has been used to validate the meta-model analytical approach and develop
the proposed mathematical model.
This study contributes a mathematical model towards the implementation
of behavioral impedance domain in geographic information systems for
transportation through a constraint management module.Postprint (published version
Adaptación a la altura y a ambientes fríos en personas con lesión medular
Objetivo: estudiar las diferencias en la adaptación respiratoria al ejercicio en condiciones medioambientales similares a las de la práctica de los deportes de invierno, entre personas físicamente activas y sanas con lesión medular y sin lesión medular. Material y método: participaron 24 voluntarios sanos y físicamente activos, 12 presentaban en su historia una lesión medular y los otros 12 no. Cada sujeto realizó tres pruebas de esfuerzo máximas con monitorización ventilatoria, pero modificando las circunstancias ambientales: a nivel del mar y a 22 - 24º C; a 3.000 metros de altura simulada y a 22 - 24º C, y a 3.000 metros de altura simulada y a 5 - 6º C. Resultados: al comparar los valores observados en las pruebas de altura simulada respecto a la realizada a nivel del mar, se observó un aumento significativo de los valores del consumo de VO2 y de la producción del VCO2. Este aumento no se acompañó de modificaciones en la ventilación, la frecuencia respiratoria o el volumen corriente. Paralelamente, la fracción espirada para el O2 y el CO2, el equivalente respiratorio para el O2 y el CO2 o la presión al final de la espiración para el O2 y el CO2 mostraron cambios estadísticamente significativos. Conclusiones: la realización de un esfuerzo intenso produce importantes cambios ventilatorios con necesidades de oxígeno superiores para una altura simulada de 3.000 metros que no cambian sustancialmente con el frío
Integrative development of a short screening questionnaire of highly processed food consumption (sQ-HPF)
Background: Recent lifestyle changes include increased consumption of highly processed foods (HPF), which has been associated with an increased risk of non-communicable diseases (NCDs). However, nutritional information relies on the estimation of HPF consumption from food-frequency questionnaires (FFQ) that are not explicitly developed for this purpose. We aimed to develop a short screening questionnaire of HPF consumption (sQ-HPF) that integrates criteria from the existing food classification systems. Methods: Data from 4400 participants (48.1% female and 51.9% male, 64.9 +/- 4.9 years) of the Spanish PREDIMED-Plus (PREvention with MEDiterranean DIet) trial were used for this analysis. Items from the FFQ were classified according to four main food processing-based classification systems (NOVA, IARC, IFIC and UNC). Participants were classified into tertiles of HPF consumption according to each system. Using binomial logistic regression, food groups associated with agreement in the highest tertile for at least two classification systems were chosen as items for the questionnaire. ROC analysis was used to determine cut-off points for the frequency of consumption of each item, from which a score was calculated. Internal consistency of the questionnaire was assessed through exploratory factor analysis (EFA) and Cronbach's analysis, and agreement with the four classifications was assessed with weighted kappa coefficients. Results: Regression analysis identified 14 food groups (items) associated with high HPF consumption for at least two classification systems. EFA showed that items were representative contributors of a single underlying factor, the HPF dietary pattern (factor loadings around 0.2). We constructed a questionnaire asking about the frequency of consumption of those items. The threshold frequency of consumption was selected using ROC analysis. Comparison of the four classification systems and the sQ-HPF showed a fair to high agreement. Significant changes in lifestyle characteristics were detected across tertiles of the sQ-HPF score. Longitudinal changes in HPF consumption were also detected by the sQ-HPF, concordantly with existing classification systems. Conclusions: We developed a practical tool to measure HPF consumption, the sQ-HPF. This may be a valuable instrument to study its relationship with NCDs
α2,3-Sialyltransferase ST3Gal III Modulates Pancreatic Cancer Cell Motility and Adhesion In Vitro and Enhances Its Metastatic Potential In Vivo
Background: Cell surface sialylation is emerging as an important feature of cancer cell metastasis. Sialyltransferase expression has been reported to be altered in tumours and may account for the formation of sialylated tumour antigens. We have focused on the influence of alpha-2,3-sialyltransferase ST3Gal III in key steps of the pancreatic tumorigenic process. Methodology/Principal Findings: ST3Gal III overexpressing pancreatic adenocarcinoma cell lines Capan-1 and MDAPanc-28 were generated. They showed an increase of the tumour associated antigen sialyl-Lewis x. The transfectants ’ E-selectin binding capacity was proportional to cell surface sialyl-Lewis x levels. Cellular migration positively correlated with ST3Gal III and sialyl-Lewis x levels. Moreover, intrasplenic injection of the ST3Gal III transfected cells into athymic nude mice showed a decrease in survival and higher metastasis formation when compared to the mock cells. Conclusion: In summary, the overexpression of ST3Gal III in these pancreatic adenocarcinoma cell lines underlines the rol
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