The Economics of Tourism and Sustainable Development, 2005
In a two sectors dynamic model we analyze the process of tourism development based on the accumul... more In a two sectors dynamic model we analyze the process of tourism development based on the accumulation of capital (building of tourism facilities) and the reallocation of land from traditional activities to the tourism sector. The model incorporates the conflict between occupation of the territory by the tourism facilities, other productive activities and availability of cultural, natural and environmental assets that are valued by residents and visitors. We characterize the process of tourism development in two settings: the socially optimal solution and a situation where the costs of tourism expansion are external to the decision makers, where externalities on residents as well as intraindustry externalities are considered. Regarding the optimal solution, we show that it is optimal to limit tourism expansion before it reaches its maximum capacity even in a context where the economic attractiveness of tourism relative to other productive sectors rise continuously. However, in this context and when all the costs of tourism development are externalities the only limit to tourism quantitative expansion is its maximum capacity determined by the availability of land. Finally, we show that excessive environmental degradation from the future generations' point of view is not a problem of discounting the future but rather a problem of externalities that affects negatively the current and future generations.
In a two sectors dynamic model we analyze the process of tourism development based on the accumul... more In a two sectors dynamic model we analyze the process of tourism development based on the accumulation of capital (building of tourism facilities) and the reallocation of land from traditional activities to the tourism sector. The model incorporates the conflict between occupation of the territory by the tourism facilities, other productive activities and availability of cultural, natural and environmental assets that are valued by residents and visitors. We characterize the process of tourism development in two settings: the socially optimal solution and a situation where the costs of tourism expansion are external to the decision makers, where externalities on residents as well as intraindustry externalities are considered. Regarding the optimal solution, we show that it is optimal to limit tourism expansion before it reaches its maximum capacity even in a context where the economic attractiveness of tourism relative to other productive sectors rise continuously. However, in this context and when all the costs of tourism development are externalities the only limit to tourism quantitative expansion is its maximum capacity determined by the availability of land. Finally, we show that excessive environmental degradation from the future generations' point of view is not a problem of discounting the future but rather a problem of externalities that affects negatively the current and future generations.
Groundwater resources are traditionally overexploited in arid and drought-prone regions with prof... more Groundwater resources are traditionally overexploited in arid and drought-prone regions with profitable irrigated agriculture, and the depletion of this groundwater results from a combination of the physical scarcity of surface sources and the lack of effective control of use rights on the part of water authorities. This is the case in the Segura River Basin of southern Spain. As a result, drought risks and structural deficits have steadily increased over the last 50 years. The Drought Management Plan recently approved by the Segura River Basin Authority aims to enforce more stringent water supply restrictions from surface sources, but the plan does not include any explicit policy to handle illegal groundwater abstraction. By using a stochastic risk assessment model, this paper shows that the implementation of the drought plan will increase the expected irrigation deficits of surface water and can, paradoxically, lead to higher drought and aquifer depletion risks than the traditional rules that the new plan replaces.
... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s... more ... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s): Birch Bayh Published: 1989 Pages: 248. Cloth: $49.95 - In Stock 978-0-8223-0839-3; Quantity; Add To Bag. Foreword / Birch Bayh ...
... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s... more ... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s): Birch Bayh Published: 1989 Pages: 248. Cloth: $49.95 - In Stock 978-0-8223-0839-3; Quantity; Add To Bag. Foreword / Birch Bayh ...
The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheim... more The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheimer's disease (AD) elicit in brain dynamics. For this task, the spontaneous magnetoencephalographic (MEG) activity from 36 AD patients, 18 MCI subjects and 24 healthy controls was analyzed. A disequilibrium measure, Jensen's divergence, was used to estimate the irregularity of neural dynamics. Results revealed that AD patients displayed significant changes (p<0.05) in the patterns of irregularity in comparison with MCI subjects and healthy controls. Slight differences between MCI subjects and elderly controls were also found. Our results suggest that AD progression is accompanied by region-specific patterns of abnormalities in the neural activity.
The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheim... more The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheimer's disease (AD) elicit in brain dynamics. For this task, the spontaneous magnetoencephalographic (MEG) activity from 36 AD patients, 18 MCI subjects and 24 healthy controls was analyzed. A disequilibrium measure, Jensen's divergence, was used to estimate the irregularity of neural dynamics. Results revealed that AD patients displayed significant changes (p<0.05) in the patterns of irregularity in comparison with MCI subjects and healthy controls. Slight differences between MCI subjects and elderly controls were also found. Our results suggest that AD progression is accompanied by region-specific patterns of abnormalities in the neural activity.
Regularity Analysis of the Magnetoencephalogram Background Activity in Alzheimer&amp;amp;#x27... more Regularity Analysis of the Magnetoencephalogram Background Activity in Alzheimer&amp;amp;#x27;s Disease Patients Using Auto Mutual Information (9781599048895): Carlos Gómez, Roberto Hornero, Daniel Abásolo, Alberto Fernández, Javier Escudero: Book Chapters.
Medical & Biological Engineering & Computing, 2008
We analysed the electroencephalogram (EEG) from Alzheimer’s disease (AD) patients with two nonlin... more We analysed the electroencephalogram (EEG) from Alzheimer’s disease (AD) patients with two nonlinear methods: approximate entropy (ApEn) and auto mutual information (AMI). ApEn quantifies regularity in data, while AMI detects linear and nonlinear dependencies in time series. EEGs from 11 AD patients and 11 age-matched controls were analysed. ApEn was significantly lower in AD patients at electrodes O1, O2, P3 and P4 (p p
Computer Methods and Programs in Biomedicine, 2007
The aim of the present study was to analyse the magnetoencephalogram (MEG) background activity in... more The aim of the present study was to analyse the magnetoencephalogram (MEG) background activity in patients with Alzheimer's disease (AD), one of the most frequent disorders among elderly population. For this pilot study, we recorded the MEGs with a 148-channel whole-head magnetometer in 20 patients with probable AD and 21 agematched control subjects. Artefact-free epochs of 3392 samples were analysed with auto mutual information (AMI). Average AMI decline rates were lower for the AD patients' recordings than for control subjects' ones. Statistically significant differences were found using a Student's t-test (p < 0.01) in 144 channels. Mean AMI values were analysed with a receiver operating characteristic curve. Sensitivity, specificity and accuracy values of 75%, 90.5% and 82.9% were obtained. Our results show that AMI estimations of the magnetic brain activity are different in both groups, hence indicating an abnormal type of dynamics associated with AD. This study suggests that AMI might help medical doctors in the diagnosis of the disease.
Alzheimer's disease (AD) is one of the most prominent neurodegenerative disorders. The aim of thi... more Alzheimer's disease (AD) is one of the most prominent neurodegenerative disorders. The aim of this research work is to study the magnetoencephalogram (MEG) background activity in AD patients using two scaling analysis methods: detrended fluctuation analysis (DFA) and backward detrended moving average (BDMA). Both measures have been designed to quantify correlations in noisy and non-stationary signals. Five minutes of recording were acquired with a 148-channel whole-head magnetometer in 15 patients with probable AD and 15 control subjects. Both DFA and BDMA exhibited two scaling regions with different slopes. Significant differences between both groups were found in the second region of DFA and in the first region of BDMA (p < 0.01, Student's t-test). Using receiver operating characteristic curves, accuracies of 83.33% with DFA and of 80% with BDMA were reached. Our findings show the usefulness of these scaling analysis methods to increase our insight into AD.
In this study we have investigated the electroencephalogram (EEG) background activity in patients... more In this study we have investigated the electroencephalogram (EEG) background activity in patients with Alzheimer's disease (AD) using non-linear analysis methods. We calculated the Lempel–Ziv (LZ) complexity – applying two different sequence conversion methods – and the central tendency measure (CTM) of the EEG in 11 AD patients and 11 age-matched control subjects. CTM quantifies the degree of variability, while LZ complexity reflects the arising rate of new patterns along with the EEG time series. We did not find significant differences between AD patients and control subjects’ EEGs with CTM. On the other hand, AD patients had significantly lower LZ complexity values (p < 0.01) at electrodes P3 and O1 with a two-symbol sequence conversion, and P3, P4, O1 and T5 using three symbols. Our results show a decreased complexity of EEG patterns in AD patients. In addition, we obtained 90.9% sensitivity and 72.7% specificity at O1, and 72.7% sensitivity and 90.9% specificity at P3 and P4. These findings suggest that LZ complexity may contribute to increase the insight into brain dysfunction in AD in ways which are not possible with more classical and conventional statistical methods.
Diagnosis of mild traumatic brain injuries (TBIs) has been difficult because of the absence of ob... more Diagnosis of mild traumatic brain injuries (TBIs) has been difficult because of the absence of obvious focal brain lesions, using conventional computed tomography (CT) or magnetic resonance imaging (MRI) scans, in a large percentage of TBIs. One useful measure that can characterize potential tissue and neural network damage objectively is Lempel-Ziv complexity (LZC) applied to magnetoencephalography (MEG) signals. LZC is a model-independent estimator of system complexity that estimates the number of different patterns in a sequence. We hypothesized that because of the potential network damage, TBIs would show a reduced level of complexity in regions that are impaired. We included 18 healthy controls and 18 military veterans with TBI in the study. Resting state MEG data were acquired, and the LZCs were analyzed across the whole brain. Our results indicated reduced complexity in multiple brain areas in TBI patients relative to the healthy controls. In addition, we detected several neuropsychological measures associated with motor responses, visual perception, and memory, correlated with LZC, which likely explains some of the cognitive deficits in TBI patients.
LIC. CARLOS A. MARTINEZ ORDOÑEZ, M.Sc HISTORIA DEL COMERCIO INTERNACIONAL Desde los tiempos más r... more LIC. CARLOS A. MARTINEZ ORDOÑEZ, M.Sc HISTORIA DEL COMERCIO INTERNACIONAL Desde los tiempos más remotos, los negocios internacionales han estado plagados de problemas incluyendo guerras, conflictos civiles, piraterías, levantamientos económicos y barreras culturales. A pesar de esto, nunca ha existido duda alguna respecto al deseo, incluso la exigencia del hombre por comerciar a través de las fronteras internacionales: de igual forma, no existe duda en cuanto a que el móvil de las ganancias ha sido la principal fuerza impulsora para motivar el crecimiento de los negocios internacionales a pesar de alguna muy sustancial falta de incentivos. Existe evidencia que, más de 2000 años antes de Cristo, los comerciantes de Mesopotamia, Grecia y Fenicia enviaban barcos mercantes alrededor del mundo conocido. En realidad se cree que algunos barcos, en ocasiones navegaban mucho más allá de estos límites y que los comerciantes fenicios visitaban Cornwall, en el sudoeste de Inglaterra, con una cierta frecuencia, probablemente para tener acceso a los ricos depósitos de estaño, un ingrediente crítico en la manufactura del bronce. Sin embargo, gradualmente el creciente comercio en el Mediterráneo quedó bajo el control de Grecia, que en 3ese tiempo era el líder tanto militar como intelectual y, para el año 500 a. De C., había signos reconocibles de especialización y producción en masa (relativa) en ese país.
The Economics of Tourism and Sustainable Development, 2005
In a two sectors dynamic model we analyze the process of tourism development based on the accumul... more In a two sectors dynamic model we analyze the process of tourism development based on the accumulation of capital (building of tourism facilities) and the reallocation of land from traditional activities to the tourism sector. The model incorporates the conflict between occupation of the territory by the tourism facilities, other productive activities and availability of cultural, natural and environmental assets that are valued by residents and visitors. We characterize the process of tourism development in two settings: the socially optimal solution and a situation where the costs of tourism expansion are external to the decision makers, where externalities on residents as well as intraindustry externalities are considered. Regarding the optimal solution, we show that it is optimal to limit tourism expansion before it reaches its maximum capacity even in a context where the economic attractiveness of tourism relative to other productive sectors rise continuously. However, in this context and when all the costs of tourism development are externalities the only limit to tourism quantitative expansion is its maximum capacity determined by the availability of land. Finally, we show that excessive environmental degradation from the future generations' point of view is not a problem of discounting the future but rather a problem of externalities that affects negatively the current and future generations.
In a two sectors dynamic model we analyze the process of tourism development based on the accumul... more In a two sectors dynamic model we analyze the process of tourism development based on the accumulation of capital (building of tourism facilities) and the reallocation of land from traditional activities to the tourism sector. The model incorporates the conflict between occupation of the territory by the tourism facilities, other productive activities and availability of cultural, natural and environmental assets that are valued by residents and visitors. We characterize the process of tourism development in two settings: the socially optimal solution and a situation where the costs of tourism expansion are external to the decision makers, where externalities on residents as well as intraindustry externalities are considered. Regarding the optimal solution, we show that it is optimal to limit tourism expansion before it reaches its maximum capacity even in a context where the economic attractiveness of tourism relative to other productive sectors rise continuously. However, in this context and when all the costs of tourism development are externalities the only limit to tourism quantitative expansion is its maximum capacity determined by the availability of land. Finally, we show that excessive environmental degradation from the future generations' point of view is not a problem of discounting the future but rather a problem of externalities that affects negatively the current and future generations.
Groundwater resources are traditionally overexploited in arid and drought-prone regions with prof... more Groundwater resources are traditionally overexploited in arid and drought-prone regions with profitable irrigated agriculture, and the depletion of this groundwater results from a combination of the physical scarcity of surface sources and the lack of effective control of use rights on the part of water authorities. This is the case in the Segura River Basin of southern Spain. As a result, drought risks and structural deficits have steadily increased over the last 50 years. The Drought Management Plan recently approved by the Segura River Basin Authority aims to enforce more stringent water supply restrictions from surface sources, but the plan does not include any explicit policy to handle illegal groundwater abstraction. By using a stochastic risk assessment model, this paper shows that the implementation of the drought plan will increase the expected irrigation deficits of surface water and can, paradoxically, lead to higher drought and aquifer depletion risks than the traditional rules that the new plan replaces.
... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s... more ... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s): Birch Bayh Published: 1989 Pages: 248. Cloth: $49.95 - In Stock 978-0-8223-0839-3; Quantity; Add To Bag. Foreword / Birch Bayh ...
... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s... more ... Hidden Illness in the White House. Author(s): Kenneth R. Crispell, Carlos Gomez Contributor(s): Birch Bayh Published: 1989 Pages: 248. Cloth: $49.95 - In Stock 978-0-8223-0839-3; Quantity; Add To Bag. Foreword / Birch Bayh ...
The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheim... more The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheimer's disease (AD) elicit in brain dynamics. For this task, the spontaneous magnetoencephalographic (MEG) activity from 36 AD patients, 18 MCI subjects and 24 healthy controls was analyzed. A disequilibrium measure, Jensen's divergence, was used to estimate the irregularity of neural dynamics. Results revealed that AD patients displayed significant changes (p<0.05) in the patterns of irregularity in comparison with MCI subjects and healthy controls. Slight differences between MCI subjects and elderly controls were also found. Our results suggest that AD progression is accompanied by region-specific patterns of abnormalities in the neural activity.
The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheim... more The aim of this study was to analyze the changes that mild cognitive impairment (MCI) and Alzheimer's disease (AD) elicit in brain dynamics. For this task, the spontaneous magnetoencephalographic (MEG) activity from 36 AD patients, 18 MCI subjects and 24 healthy controls was analyzed. A disequilibrium measure, Jensen's divergence, was used to estimate the irregularity of neural dynamics. Results revealed that AD patients displayed significant changes (p<0.05) in the patterns of irregularity in comparison with MCI subjects and healthy controls. Slight differences between MCI subjects and elderly controls were also found. Our results suggest that AD progression is accompanied by region-specific patterns of abnormalities in the neural activity.
Regularity Analysis of the Magnetoencephalogram Background Activity in Alzheimer&amp;amp;#x27... more Regularity Analysis of the Magnetoencephalogram Background Activity in Alzheimer&amp;amp;#x27;s Disease Patients Using Auto Mutual Information (9781599048895): Carlos Gómez, Roberto Hornero, Daniel Abásolo, Alberto Fernández, Javier Escudero: Book Chapters.
Medical & Biological Engineering & Computing, 2008
We analysed the electroencephalogram (EEG) from Alzheimer’s disease (AD) patients with two nonlin... more We analysed the electroencephalogram (EEG) from Alzheimer’s disease (AD) patients with two nonlinear methods: approximate entropy (ApEn) and auto mutual information (AMI). ApEn quantifies regularity in data, while AMI detects linear and nonlinear dependencies in time series. EEGs from 11 AD patients and 11 age-matched controls were analysed. ApEn was significantly lower in AD patients at electrodes O1, O2, P3 and P4 (p p
Computer Methods and Programs in Biomedicine, 2007
The aim of the present study was to analyse the magnetoencephalogram (MEG) background activity in... more The aim of the present study was to analyse the magnetoencephalogram (MEG) background activity in patients with Alzheimer's disease (AD), one of the most frequent disorders among elderly population. For this pilot study, we recorded the MEGs with a 148-channel whole-head magnetometer in 20 patients with probable AD and 21 agematched control subjects. Artefact-free epochs of 3392 samples were analysed with auto mutual information (AMI). Average AMI decline rates were lower for the AD patients' recordings than for control subjects' ones. Statistically significant differences were found using a Student's t-test (p < 0.01) in 144 channels. Mean AMI values were analysed with a receiver operating characteristic curve. Sensitivity, specificity and accuracy values of 75%, 90.5% and 82.9% were obtained. Our results show that AMI estimations of the magnetic brain activity are different in both groups, hence indicating an abnormal type of dynamics associated with AD. This study suggests that AMI might help medical doctors in the diagnosis of the disease.
Alzheimer's disease (AD) is one of the most prominent neurodegenerative disorders. The aim of thi... more Alzheimer's disease (AD) is one of the most prominent neurodegenerative disorders. The aim of this research work is to study the magnetoencephalogram (MEG) background activity in AD patients using two scaling analysis methods: detrended fluctuation analysis (DFA) and backward detrended moving average (BDMA). Both measures have been designed to quantify correlations in noisy and non-stationary signals. Five minutes of recording were acquired with a 148-channel whole-head magnetometer in 15 patients with probable AD and 15 control subjects. Both DFA and BDMA exhibited two scaling regions with different slopes. Significant differences between both groups were found in the second region of DFA and in the first region of BDMA (p < 0.01, Student's t-test). Using receiver operating characteristic curves, accuracies of 83.33% with DFA and of 80% with BDMA were reached. Our findings show the usefulness of these scaling analysis methods to increase our insight into AD.
In this study we have investigated the electroencephalogram (EEG) background activity in patients... more In this study we have investigated the electroencephalogram (EEG) background activity in patients with Alzheimer's disease (AD) using non-linear analysis methods. We calculated the Lempel–Ziv (LZ) complexity – applying two different sequence conversion methods – and the central tendency measure (CTM) of the EEG in 11 AD patients and 11 age-matched control subjects. CTM quantifies the degree of variability, while LZ complexity reflects the arising rate of new patterns along with the EEG time series. We did not find significant differences between AD patients and control subjects’ EEGs with CTM. On the other hand, AD patients had significantly lower LZ complexity values (p < 0.01) at electrodes P3 and O1 with a two-symbol sequence conversion, and P3, P4, O1 and T5 using three symbols. Our results show a decreased complexity of EEG patterns in AD patients. In addition, we obtained 90.9% sensitivity and 72.7% specificity at O1, and 72.7% sensitivity and 90.9% specificity at P3 and P4. These findings suggest that LZ complexity may contribute to increase the insight into brain dysfunction in AD in ways which are not possible with more classical and conventional statistical methods.
Diagnosis of mild traumatic brain injuries (TBIs) has been difficult because of the absence of ob... more Diagnosis of mild traumatic brain injuries (TBIs) has been difficult because of the absence of obvious focal brain lesions, using conventional computed tomography (CT) or magnetic resonance imaging (MRI) scans, in a large percentage of TBIs. One useful measure that can characterize potential tissue and neural network damage objectively is Lempel-Ziv complexity (LZC) applied to magnetoencephalography (MEG) signals. LZC is a model-independent estimator of system complexity that estimates the number of different patterns in a sequence. We hypothesized that because of the potential network damage, TBIs would show a reduced level of complexity in regions that are impaired. We included 18 healthy controls and 18 military veterans with TBI in the study. Resting state MEG data were acquired, and the LZCs were analyzed across the whole brain. Our results indicated reduced complexity in multiple brain areas in TBI patients relative to the healthy controls. In addition, we detected several neuropsychological measures associated with motor responses, visual perception, and memory, correlated with LZC, which likely explains some of the cognitive deficits in TBI patients.
LIC. CARLOS A. MARTINEZ ORDOÑEZ, M.Sc HISTORIA DEL COMERCIO INTERNACIONAL Desde los tiempos más r... more LIC. CARLOS A. MARTINEZ ORDOÑEZ, M.Sc HISTORIA DEL COMERCIO INTERNACIONAL Desde los tiempos más remotos, los negocios internacionales han estado plagados de problemas incluyendo guerras, conflictos civiles, piraterías, levantamientos económicos y barreras culturales. A pesar de esto, nunca ha existido duda alguna respecto al deseo, incluso la exigencia del hombre por comerciar a través de las fronteras internacionales: de igual forma, no existe duda en cuanto a que el móvil de las ganancias ha sido la principal fuerza impulsora para motivar el crecimiento de los negocios internacionales a pesar de alguna muy sustancial falta de incentivos. Existe evidencia que, más de 2000 años antes de Cristo, los comerciantes de Mesopotamia, Grecia y Fenicia enviaban barcos mercantes alrededor del mundo conocido. En realidad se cree que algunos barcos, en ocasiones navegaban mucho más allá de estos límites y que los comerciantes fenicios visitaban Cornwall, en el sudoeste de Inglaterra, con una cierta frecuencia, probablemente para tener acceso a los ricos depósitos de estaño, un ingrediente crítico en la manufactura del bronce. Sin embargo, gradualmente el creciente comercio en el Mediterráneo quedó bajo el control de Grecia, que en 3ese tiempo era el líder tanto militar como intelectual y, para el año 500 a. De C., había signos reconocibles de especialización y producción en masa (relativa) en ese país.
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