847 resultados para Interconnected microgrids
Resumo:
Today, databases have become an integral part of information systems. In the past two decades, we have seen different database systems being developed independently and used in different applications domains. Today's interconnected networks and advanced applications, such as data warehousing, data mining & knowledge discovery and intelligent data access to information on the Web, have created a need for integrated access to such heterogeneous, autonomous, distributed database systems. Heterogeneous/multidatabase research has focused on this issue resulting in many different approaches. However, a single, generally accepted methodology in academia or industry has not emerged providing ubiquitous intelligent data access from heterogeneous, autonomous, distributed information sources. ^ This thesis describes a heterogeneous database system being developed at High-performance Database Research Center (HPDRC). A major impediment to ubiquitous deployment of multidatabase technology is the difficulty in resolving semantic heterogeneity. That is, identifying related information sources for integration and querying purposes. Our approach considers the semantics of the meta-data constructs in resolving this issue. The major contributions of the thesis work include: (i) providing a scalable, easy-to-implement architecture for developing a heterogeneous multidatabase system, utilizing Semantic Binary Object-oriented Data Model (Sem-ODM) and Semantic SQL query language to capture the semantics of the data sources being integrated and to provide an easy-to-use query facility; (ii) a methodology for semantic heterogeneity resolution by investigating into the extents of the meta-data constructs of component schemas. This methodology is shown to be correct, complete and unambiguous; (iii) a semi-automated technique for identifying semantic relations, which is the basis of semantic knowledge for integration and querying, using shared ontologies for context-mediation; (iv) resolutions for schematic conflicts and a language for defining global views from a set of component Sem-ODM schemas; (v) design of a knowledge base for storing and manipulating meta-data and knowledge acquired during the integration process. This knowledge base acts as the interface between integration and query processing modules; (vi) techniques for Semantic SQL query processing and optimization based on semantic knowledge in a heterogeneous database environment; and (vii) a framework for intelligent computing and communication on the Internet applying the concepts of our work. ^
Resumo:
Mediation techniques provide interoperability and support integrated query processing among heterogeneous databases. While such techniques help data sharing among different sources, they increase the risk for data security, such as violating access control rules. Successful protection of information by an effective access control mechanism is a basic requirement for interoperation among heterogeneous data sources. ^ This dissertation first identified the challenges in the mediation system in order to achieve both interoperability and security in the interconnected and collaborative computing environment, which includes: (1) context-awareness, (2) semantic heterogeneity, and (3) multiple security policy specification. Currently few existing approaches address all three security challenges in mediation system. This dissertation provides a modeling and architectural solution to the problem of mediation security that addresses the aforementioned security challenges. A context-aware flexible authorization framework was developed in the dissertation to deal with security challenges faced by mediation system. The authorization framework consists of two major tasks, specifying security policies and enforcing security policies. Firstly, the security policy specification provides a generic and extensible method to model the security policies with respect to the challenges posed by the mediation system. The security policies in this study are specified by 5-tuples followed by a series of authorization constraints, which are identified based on the relationship of the different security components in the mediation system. Two essential features of mediation systems, i. e., relationship among authorization components and interoperability among heterogeneous data sources, are the focus of this investigation. Secondly, this dissertation supports effective access control on mediation systems while providing uniform access for heterogeneous data sources. The dynamic security constraints are handled in the authorization phase instead of the authentication phase, thus the maintenance cost of security specification can be reduced compared with related solutions. ^
Resumo:
Access control (AC) limits access to the resources of a system only to authorized entities. Given that information systems today are increasingly interconnected, AC is extremely important. The implementation of an AC service is a complicated task. Yet the requirements to an AC service vary a lot. Accordingly, the design of an AC service should be flexible and extensible in order to save development effort and time. Unfortunately, with conventional object-oriented techniques, when an extension has not been anticipated at the design time, the modification incurred by the extension is often invasive. Invasive changes destroy design modularity, further deteriorate design extensibility, and even worse, they reduce product reliability. ^ A concern is crosscutting if it spans multiple object-oriented classes. It was identified that invasive changes were due to the crosscutting nature of most unplanned extensions. To overcome this problem, an aspect-oriented design approach for AC services was proposed, as aspect-oriented techniques could effectively encapsulate crosscutting concerns. The proposed approach was applied to develop an AC framework that supported role-based access control model. In the framework, the core role-based access control mechanism is given in an object-oriented design, while each extension is captured as an aspect. The resulting framework is well-modularized, flexible, and most importantly, supports noninvasive adaptation. ^ In addition, a process to formalize the aspect-oriented design was described. The purpose is to provide high assurance for AC services. Object-Z was used to specify the static structure and Predicate/Transition net was used to model the dynamic behavior. Object-Z was extended to facilitate specification in an aspect-oriented style. The process of formal modeling helps designers to enhance their understanding of the design, hence to detect problems. Furthermore, the specification can be mathematically verified. This provides confidence that the design is correct. It was illustrated through an example that the model was ready for formal analysis. ^
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Tobacco was of primary importance to Spain, and its impact on Cuba's economy and society was greater than just the numbers of farms, workers, or production, demonstrated by the Spanish crown's outlay of monies for capital assets, bureaucrats' salaries, and payments to farmers for their crop. This study is a micro- and macro-level study of rural life in colonial Cuba and the interconnected relationships among society, agricultural production, state control, and the island's economic development. ^ By placing Cuba's tobacco farmers at the forefront of this social history, this work revisits and offers alternatives to two prevailing historiographical views of rural Cuba from 1763 (the year Havana returned to Spanish control following the Seven Years' War) to 1817 (the final year of the 100-year royal monopoly on Cuban tobacco). Firstly, it argues against the primacy of sugar over other agricultural crops, a view that has shaped decades of scholarship, and challenges the thesis which maintains the Cuban tobacco farmer was almost exclusively poor, white, and employed free labor, rather than slaves, in the production of their crop. ^ This study establishes the importance of tobacco as an agricultural product, and argues that Cuban tobacco growers were a heterogeneous group, revealing the role that its cultivation may have played in helping some slaves earn their freedom. ^
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The purpose of this study was to gain an understanding and gather insight into the experiences of Cuban American women attending a 4-year, public, Hispanic Serving Institution and how those experiences influenced their identity development. This was accomplished by conducting in-depth interviews and focus groups with 12 self-identified Cuban American women who were classified as sophomores, juniors, seniors, or graduate students. All of the participants had attended Florida International University for at least 1 year. The women had varying degrees of on and off campus academic and campus involvement activities. Participants were asked about six topics: (a) family, (b) cultural influences, (c) gender, (d) ethical and moral development, (e) education, and (f) ethnic identity. Based on the coding of the data provided by the participants, several interconnected themes emerged including the importance of family, familial support, cultural pride, expected gender roles, core values, decision making, biculturalism, and the value of attending a Hispanic Serving Institution. These themes were found to be all related to the identity development of the participants. It was found that looking at identity through a multidimensional lens is essential. Looking at personal growth and development through anthropological, sociological, and psychosocial lenses gave greater insight to a population of students who have been largely underrepresented in the literature. The findings of this case study are that culture is contextual and identity development is complex for first and second generation Cuban American women attending a Hispanic Serving Institution in a majority minority city. It was found that several factors, including the importance of family and gender roles, were not found to be more important than one another; rather they supported each other in regards to the participants' identity development. The notion of biculturalism as it has been presented in the literature was challenged in this study as it was found that the participants' experiences living and attending a school in a majority minority city presented a new way of understanding what it might mean to be bicultural. For professionals in the field, the findings of this study may lead to a broader understanding of nuances within the Hispanic community and a better understanding of the distinctiveness of what it means to be a Cuban American woman.
Resumo:
This dissertation analyzes the obstacles against further cooperation in international economic relations. The first essay explains the gradual nature of trade liberalization. I show that existence of asymmetric information between governments provides a sufficient reason for gradualism to exist. Governments prefer starting small to reduce the cost of partner’s betrayal when there is sufficient degree of information asymmetry regarding the partner’s type. Learning about partner’s incentive structure enhances expectations, encouraging governments to increase their current level of cooperation. Specifically, the uninformed government’s subjective belief for the trading partner being good is improved as the partner acts cooperatively. This updated belief, in turn, lowers the subjective probability of future betrayal, enabling further progress in cooperation. The second essay analyzes the relationship between two countries facing two policy dilemmas in an environment with two way goods and capital flows. When issues are independent and countries are symmetric, signing separate agreements for tariffs (Free Trade Agreements-FTA) and for taxes (Tax Treaties-TT) provides the identical level of enforcement as signing a linked agreement. However, linkage can still improve the joint welfare by transferring the slack enforcement power in a case of asymmetric issues or countries. I report non-results in two cases where the policy issues are interconnected due to technological spillover effect of FDI. Moreover, I show that linking the agreements actually reduces enforcement when agreements are linked under a limited punishment rule and policy variables are strategic substitutes. The third essay investigates the welfare/enforcement consequences of linking trade and environmental agreements. In the standard literature, linking the agreements generate non-trivial results only when there is structural relation between the issues. I focus on institutional design of the linkage and show that even if environmental aspects of international trade are negligible linking the agreements might still have some interesting welfare implications under current GATT Rules. Specifically, when traded goods are substitutes in consumption, linking the environmental agreement with trade agreement under the Withdrawal of Equivalent Concession Rule (Article XXVIII) will reduce the enforcement. However, enforcement in environmental issue increases when the same rule is implemented in the absence of linkage.
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The United States has been increasingly concerned with the transnational threat posed by infectious diseases. Effective policy implementation to contain the spread of these diseases requires active engagement and support of the American public. To influence American public opinion and enlist support for related domestic and foreign policies, both domestic agencies and international organizations have framed infectious diseases as security threats, human rights disasters, economic risks, and as medical dangers. This study investigates whether American attitudes and opinions about infectious diseases are influenced by how the issue is framed. It also asks which issue frame has been most influential in shaping public opinion about global infectious diseases when people are exposed to multiple frames. The impact of media frames on public perception of infectious diseases is examined through content analysis of newspaper reports. Stories on SARS, avian flu, and HIV/AIDS were sampled from coverage in The New York Times and The Washington Post between 1999 and 2007. Surveys of public opinion on infectious diseases in the same time period were also drawn from databases like Health Poll Search and iPoll. Statistical analysis tests the relationship between media framing of diseases and changes in public opinion. Results indicate that no one frame was persuasive across all diseases. The economic frame had a significant effect on public opinion about SARS, as did the biomedical frame in the case of avian flu. Both the security and human rights frames affected opinion and increased public support for policies intended to prevent or treat HIV/AIDS. The findings also address the debate on the role and importance of domestic public opinion as a factor in domestic and foreign policy decisions of governments in an increasingly interconnected world. The public is able to make reasonable evaluations of the frames and the domestic and foreign policy issues emphasized in the frames.
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Modern power networks incorporate communications and information technology infrastructure into the electrical power system to create a smart grid in terms of control and operation. The smart grid enables real-time communication and control between consumers and utility companies allowing suppliers to optimize energy usage based on price preference and system technical issues. The smart grid design aims to provide overall power system monitoring, create protection and control strategies to maintain system performance, stability and security. This dissertation contributed to the development of a unique and novel smart grid test-bed laboratory with integrated monitoring, protection and control systems. This test-bed was used as a platform to test the smart grid operational ideas developed here. The implementation of this system in the real-time software creates an environment for studying, implementing and verifying novel control and protection schemes developed in this dissertation. Phasor measurement techniques were developed using the available Data Acquisition (DAQ) devices in order to monitor all points in the power system in real time. This provides a practical view of system parameter changes, system abnormal conditions and its stability and security information system. These developments provide valuable measurements for technical power system operators in the energy control centers. Phasor Measurement technology is an excellent solution for improving system planning, operation and energy trading in addition to enabling advanced applications in Wide Area Monitoring, Protection and Control (WAMPAC). Moreover, a virtual protection system was developed and implemented in the smart grid laboratory with integrated functionality for wide area applications. Experiments and procedures were developed in the system in order to detect the system abnormal conditions and apply proper remedies to heal the system. A design for DC microgrid was developed to integrate it to the AC system with appropriate control capability. This system represents realistic hybrid AC/DC microgrids connectivity to the AC side to study the use of such architecture in system operation to help remedy system abnormal conditions. In addition, this dissertation explored the challenges and feasibility of the implementation of real-time system analysis features in order to monitor the system security and stability measures. These indices are measured experimentally during the operation of the developed hybrid AC/DC microgrids. Furthermore, a real-time optimal power flow system was implemented to optimally manage the power sharing between AC generators and DC side resources. A study relating to real-time energy management algorithm in hybrid microgrids was performed to evaluate the effects of using energy storage resources and their use in mitigating heavy load impacts on system stability and operational security.
Resumo:
Efficient and reliable techniques for power delivery and utilization are needed to account for the increased penetration of renewable energy sources in electric power systems. Such methods are also required for current and future demands of plug-in electric vehicles and high-power electronic loads. Distributed control and optimal power network architectures will lead to viable solutions to the energy management issue with high level of reliability and security. This dissertation is aimed at developing and verifying new techniques for distributed control by deploying DC microgrids, involving distributed renewable generation and energy storage, through the operating AC power system. To achieve the findings of this dissertation, an energy system architecture was developed involving AC and DC networks, both with distributed generations and demands. The various components of the DC microgrid were designed and built including DC-DC converters, voltage source inverters (VSI) and AC-DC rectifiers featuring novel designs developed by the candidate. New control techniques were developed and implemented to maximize the operating range of the power conditioning units used for integrating renewable energy into the DC bus. The control and operation of the DC microgrids in the hybrid AC/DC system involve intelligent energy management. Real-time energy management algorithms were developed and experimentally verified. These algorithms are based on intelligent decision-making elements along with an optimization process. This was aimed at enhancing the overall performance of the power system and mitigating the effect of heavy non-linear loads with variable intensity and duration. The developed algorithms were also used for managing the charging/discharging process of plug-in electric vehicle emulators. The protection of the proposed hybrid AC/DC power system was studied. Fault analysis and protection scheme and coordination, in addition to ideas on how to retrofit currently available protection concepts and devices for AC systems in a DC network, were presented. A study was also conducted on the effect of changing the distribution architecture and distributing the storage assets on the various zones of the network on the system's dynamic security and stability. A practical shipboard power system was studied as an example of a hybrid AC/DC power system involving pulsed loads. Generally, the proposed hybrid AC/DC power system, besides most of the ideas, controls and algorithms presented in this dissertation, were experimentally verified at the Smart Grid Testbed, Energy Systems Research Laboratory. All the developments in this dissertation were experimentally verified at the Smart Grid Testbed.
Resumo:
This dissertation consists of three essays on different aspects of water management. The first essay focuses on the sustainability of freshwater use by introducing the notion that altruistic parents do bequeath economic assets for their offspring. Constructing a two-period, over-lapping generational model, an optimal ratio of consumption and pollution for old and young generations in each period is determined. Optimal levels of water consumption and pollution change according to different parameters, such as, altruistic degree, natural recharge rate, and population growth. The second essay concerns water sharing between countries in the case of trans-boundary river basins. The paper recognizes that side payments fail to forge water-sharing agreement among the international community and that downstream countries have weak bargaining power. An interconnected game approach is developed by linking the water allocation issue with other non-water issues such as trade or border security problems, creating symmetry between countries in bargaining power. An interconnected game forces two countries to at least partially cooperate under some circumstances. The third essay introduces the concept of virtual water (VW) into a traditional international trade model in order to estimate water savings for a water scarce country. A two country, two products and two factors trade model is developed, which includes not only consumers and producer's surplus, but also environmental externality of water use. The model shows that VW trade saves water and increases global and local welfare. This study should help policy makers to design appropriate subsidy or tax policy to promote water savings especially in water scarce countries.^
Resumo:
Distributed Generation (DG) from alternate sources and smart grid technologies represent good solutions for the increase in energy demands. Employment of these DG assets requires solutions for the new technical challenges that are accompanied by the integration and interconnection into operational power systems. A DG infrastructure comprised of alternate energy sources in addition to conventional sources, is developed as a test bed. The test bed is operated by synchronizing, wind, photovoltaic, fuel cell, micro generator and energy storage assets, in addition to standard AC generators. Connectivity of these DG assets is tested for viability and for their operational characteristics. The control and communication layers for dynamic operations are developed to improve the connectivity of alternates to the power system. A real time application for the operation of alternate sources in microgrids is developed. Multi agent approach is utilized to improve stability and sequences of actions for black start are implemented. Experiments for control and stability issues related to dynamic operation under load conditions have been conducted and verified.
Resumo:
Today, databases have become an integral part of information systems. In the past two decades, we have seen different database systems being developed independently and used in different applications domains. Today's interconnected networks and advanced applications, such as data warehousing, data mining & knowledge discovery and intelligent data access to information on the Web, have created a need for integrated access to such heterogeneous, autonomous, distributed database systems. Heterogeneous/multidatabase research has focused on this issue resulting in many different approaches. However, a single, generally accepted methodology in academia or industry has not emerged providing ubiquitous intelligent data access from heterogeneous, autonomous, distributed information sources. This thesis describes a heterogeneous database system being developed at Highperformance Database Research Center (HPDRC). A major impediment to ubiquitous deployment of multidatabase technology is the difficulty in resolving semantic heterogeneity. That is, identifying related information sources for integration and querying purposes. Our approach considers the semantics of the meta-data constructs in resolving this issue. The major contributions of the thesis work include: (i.) providing a scalable, easy-to-implement architecture for developing a heterogeneous multidatabase system, utilizing Semantic Binary Object-oriented Data Model (Sem-ODM) and Semantic SQL query language to capture the semantics of the data sources being integrated and to provide an easy-to-use query facility; (ii.) a methodology for semantic heterogeneity resolution by investigating into the extents of the meta-data constructs of component schemas. This methodology is shown to be correct, complete and unambiguous; (iii.) a semi-automated technique for identifying semantic relations, which is the basis of semantic knowledge for integration and querying, using shared ontologies for context-mediation; (iv.) resolutions for schematic conflicts and a language for defining global views from a set of component Sem-ODM schemas; (v.) design of a knowledge base for storing and manipulating meta-data and knowledge acquired during the integration process. This knowledge base acts as the interface between integration and query processing modules; (vi.) techniques for Semantic SQL query processing and optimization based on semantic knowledge in a heterogeneous database environment; and (vii.) a framework for intelligent computing and communication on the Internet applying the concepts of our work.
Resumo:
This dissertation seeks to reflect about the relations between danced movement and body space (Kinesphere), and their contributions to the expansion of the expressive possibilities of the subject on dancing. According to Rudolf Laban there is no space that is empty, because it is always being modified and signified at every moment by the movement. Space exists because we interact with it, at the same time movement occours configuring a signifcant space that is incessantly transformed. In this sense, space, body and movement appear in this research as interconnected and interdependent. For this discussion we have as main interlocutor the studies of Rudolf Laban. The nature of this research is qualitative and descriptive. This is a context that embraces the phenomenon of dance and as such it is based on a dimension that doesn't deal with mensurability, but with the art scene, fruitful in its infinite openness to the creation of multiple significances for what has been lived. We also propose to present a report about the practical study developed in the discipline Coreologia in the licentiate course of Dance in UFRN, as well as the analysis of the interviews applied to students of this curricular component. The questions were developed in a way that lead to a reflection about the experience of those interviewed in this discipline, thus generating material for us to discuss how the students perceive dance based on the relational study between space and movement. We realize that this study may favor an understanding of the relations that the experienced movement in the act of the dance weaves along the spatiality that receives and fills our bodies, resignifying the vision of a space which is restrict to the mere place were the body moves and occupies. It also favors the reflections concerning the body that moves and creates spatiality when dancing, thereby bringing to the Performing Arts a chance to think and to experience on the expansion of the expressive gesture in dance and beyond it, led by the recognition of the principles that organize human movement pointed by Laban. It also contributes on the formation of the students in licentiate courses of Dance by questioning the ways to appropriate the contents worked in a graduation discipline as regards to the availability of the body for dance. This dissertation is divided in three parts, called Impulsos. In the First Impulso: “Primeiros Gestos Textuais”, we find an introduction to concepts and ideas of body, movement and space that permeates all the work. In the Second Impulso: "Nós", the triad body-space-motion is discussed using the metaphorical image of a knot that binds these three concepts. The third and final Impulso: "Enlaces" deal with impressions and discoveries lived during the experimentation of the principles of inter-actions studied here, in the lessons of the already mentioned discipline
Resumo:
The investigation analyze s the role of the municipalities in the ongoing development of literacy teachers, having as a field of study the municipalities of Jaguaruana and Palhano, both in the State of Ceará. The political - educational space adopted as a sample of the study is the p eriod between the years 2003 and 2006, when the emphasis on cooperative action among the federated entities is observed in the Government’s guidelines and Brazilian educational policies, showing the municipal presence in the implementation and execution of these policies. T he historical - dialectical materialistic perspective, understood as an analysis of the social reality as historical elaboration and product of the human praxis, is expressed as the required theoretical - methodological path. The investigatio n is operationalized through interconnected stages: one that involves bibliographical and documental analysis, in which the theoretical input of the research is added, as well as the Federal, State and M unicipal documents accessed ; and another, regarding t he field work, studying the specific character of the object and its mutual rela tionships in the municipalities . The research brings the notion of intergovernmental relationships and cooperative mechanisms as central theoretical tools and, dialoguing with them, ideas such as decentralization, municipalization and municipal autonomy are inserted into a theoretical/practical body, through which the historical and logical aspects of the object are detailed. The study describes and interprets the policies of on going development of literacy teachers with focus on the national guidelines formulated since the 1990’s and on the govern mental incorporation in the national and subnational spaces. In this sense, the analysis is based on the comprehension of the interrel ationship between the municipal policies and the p olicies created by the S tate or Federal G overnments in order to offer ongoing development of literacy teachers. Considering the investigated sample, it shows how the municipal role and the relationships bet ween the State and municipalities of Ceará have emerged, as well as their characteristics regarding the education management policies, taking into account the practices of municipalization and cooperation between the State and municipalities in their histo rical composition. It shows the practices which aim at the ongoing development of literacy teachers observed in the researched municipalities, pointing out the realities and specific marks left by municipal presence in the area, demonstrating the assigned role and the role played. Based on the points of view of the managers interviewed in the municipalities of Jaguaruana e Palhano, it is possible to note the meaning and effectiveness of the policies carried out. With such elements, it discusses the municipa l asymmetries in their homogeneities and heterogeneities rega rding the execution of their federative role. The analysis shows that th e role of the municipalities vary according to the historical, political and social interventions in each municipality. In the fields of formulation and execution of educational policies, the actions of the municipal governments, situated and with expressive interferences, reveal asymmetries in the sense that some municipalities have bigger autonomy and participate more effect ively in the production and distribution of policies than others. In terms of the researched realities, the study shows that taking care of the policies of ongoing development of literacy teachers is not a task that should be assigned exclusively to the mu nicipalities, nonetheless it is a role that they play with varying degrees of success. This role is in fact a joint competence of the federated entities, in the scope the Brazilian cooperative federalism.
Resumo:
The circadian timing system (CTS), in rodents, consists of interconnected neural structures such as the suprachiasmatic nucleus (SCN) of the hypothalamus, Intergeniculate Leaflet (IGL) of the thalamus, synchronous pathways and behavioral effectors. The SCN has been described as the major circadian pacemaker in several species of mammals, while the IGL appears to be involved in integration of photic and non-photic clues relaying them to SCN. The CTS allows an ordered internal temporal organization to the organism, providing the proper execution of physiological and behavioral mechanisms, which brings homeostasis. However, this stability is disrupted with aging process causing numerous pathological disorders, ranging from simple loss of physiological functions to decreases in cognitive performance. Therefore, is fundamental understanding the effects of senescence in this system. In this context, is proposed in this study to check if there are changes in IGL cytoarchitecture, neurochemical and retinal afferent markers with aging and their possible morpho-functional implications. To achieve this goal wistar rats were divided into 3 groups: young (3 months); Middle Age (13 months); Old (23 months). They were submitted to paraformaldhyde (4%) transcardiac perfusion to tissue fixation. Then, they had their brain removed and sectioned in 30 µm slices, which every sixth section were collected. This sections were processed by nissl method and immunostaining for GFAP, GAD, ENK, NPY and CTb in order to analyze the IGL features. It was observed a cell loss in middle age and old animals at Nissl, NPY and CTb stains. In addition, it was shown a increase in GFAP in middle aged animals compared to young and old ones. No differences were found in other neurochemichal stains. These data suggests IGL loss retinal afferents and neurons, in special the NPY-IR ones, likely having a compensatory gliogenesis. This supports the correlations between the CTS functional deficits and an anatomical deterioration of its components with the aging process.