Analysis and Design of a Dual-Port Compact Microstrip Antenna

A dual-port dual-polarized compact microstrip antenna for avoiding cross coupling between the two frequency bands is proposed and analyzed. This antenna offers channel isolation better than 25 dB, and is more compact compared to a conventional rectangular patch. Analytical equations for calculating the resonant frequencies at both ports are also presented. The theoretical calculations are verified using experimental results

Design and Development of re configurable compact cross patch antenna for switchable polarization

Antennas are necessary and vital components of communication and radar systems, but sometimes their inability to adjust to new operating scenarios can limit system performance. Reconfigurable antennas can adjust with changing system requirements or environmental conditions and provide additional levels of functionality that may result in wider instantaneous frequency bandwidths, more extensive scan volumes, and radiation patterns with more desirable side lobe distributions. Their agility and diversity created new horizons for different types of applications especially in cognitive radio, Multiple Input Multiple Output Systems, satellites and many other applications. Reconfigurable antennas satisfy the requirements for increased functionality, such as direction finding, beam steering, radar, control and command, within a confined volume. The intelligence associated with the reconfigurable antennas revolved around switching mechanisms utilized. In the present work, we have investigated frequency reconfigurable polarization diversity antennas using two methods: 1. By using low-loss, high-isolation switches such as PIN diode, the antenna can be structurally reconfigured to maintain the elements near their resonant dimensions for different frequency bands and/or polarization. 2. Secondly, the incorporation of variable capacitors or varactors, to overcome many problems faced in using switches and their biasing. The performances of these designs have been studied using standard simulation tools used in industry/academia and they have been experimentally verified. Antenna design guidelines are also deduced by accounting the resonances. One of the major contributions of the thesis lies in the analysis of the designed antennas using FDTD based numerical computation to validate their performance.

High-momentum proton removal from 16 O and the (e,e'p) cross section

The cross section for the removal of high-momentum protons from 16O is calculated for high missing energies. The admixture of high-momentum nucleons in the 16O ground state is obtained by calculating the single-hole spectral function directly in the finite nucleus with the inclusion of short-range and tensor correlations induced by a realistic meson-exchange interaction. The presence of high-momentum nucleons in the transition to final states in 15N at 60¿100 MeV missing energy is converted to the coincidence cross section for the (e,e¿p) reaction by including the coupling to the electromagnetic probe and the final state interactions of the outgoing proton in the same way as in the standard analysis of the experimental data. Detectable cross sections for the removal of a single proton at these high missing energies are obtained which are considerably larger at higher missing momentum than the corresponding cross sections for the p-wave quasihole transitions. Cross sections for these quasihole transitions are compared with the most recent experimental data available.

Status and Potential of Smallholder Livestock Production Systems in Xishuangbanna, southern P.R. China

With Chinas rapid economic development during the last decades, the national demand for livestock products has quadrupled within the last 20 years. Most of that increase in demand has been answered by subsidized industrialized production systems, while million of smallholders, which still provide the larger share of livestock products in the country, have been neglected. Fostering those systems would help China to lower its strong urban migration streams, enhance the livelihood of poorer rural population and provide environmentally save livestock products which have a good chance to satisfy customers demand for ecological food. Despite their importance, China’s smallholder livestock keepers have not yet gained appropriate attention from governmental authorities and researchers. However, profound analysis of those systems is required so that adequate support can lead to a better resource utilization and productivity in the sector. To this aim, this pilot study analyzes smallholder livestock production systems in Xishuangbanna, located in southern China. The area is bordered by Lao and Myanmar and geographically counts as tropical region. Its climate is characterized by dry and temperate winters and hot summers with monsoon rains from May to October. While the regionis plain, at about 500 m asl above sea level in the south, outliers of the Himalaya mountains reach out into the north of Xishuangbanna, where the highest peak reaches 2400 m asl. Except of one larger city, Jinghong, Xishuangbanna mainly is covered by tropical rainforest, areas under agricultural cultivation and villages. The major income is generated through inner-Chinese tourism and agricultural production. Intensive rubber plantations are distinctive for the lowland plains while small-scaled traditional farms are scattered in the mountane regions. In order to determine the current state and possible future chances of smallholder livestock production in that region, this study analyzed the current status of the smallholder livestock sector in the Naban River National Nature Reserve (NRNNR), an area which is largely representative for the whole prefecture. It covers an area of about 50square kilometer and reaches from 470 up to 2400 m asl. About 5500 habitants of different ethnic origin are situated in 24 villages. All data have been collected between October 2007 and May 2010. Three major objectives have been addressed in the study: 1. Classifying existing pig production systems and exploring respective pathways for development 2. Quantifying the performance of pig breeding systemsto identify bottlenecks for production 3. Analyzing past and current buffalo utilization to determine the chances and opportunities of buffalo keeping in the future In order to classify the different pig production s ystems, a baseline survey (n=204, stratified cluster sampling) was carried out to gain data about livestock species, numbers, management practices, cultivated plant species and field sizes as well associo-economic characteristics. Sampling included two clusters at village level (altitude, ethnic affiliation), resulting in 13 clusters of which 13-17 farms were interviewed respectively. Categorical Principal Component Analysis (CatPCA) and a two-step clustering algorithm have been applied to identify determining farm characteristics and assort recorded households into classes of livestock production types. The variables keep_sow_yes/no, TLU_pig, TLU_buffalo, size_of_corn_fields, altitude_class, size_of_tea_plantationand size_of_rubber_fieldhave been found to be major determinants for the characterization of the recorded farms. All farms have extensive or semi-intensive livestock production, pigs and buffaloes are predominant livestock species while chicken and aquaculture are available but play subordinate roles for livelihoods. All pig raisers rely on a single local breed, which is known as Small Ear Pig (SMEP) in the region. Three major production systemshave been identified: Livestock-corn based LB; 41%), rubber based (RB; 39%) and pig based (PB;20%) systems. RB farms earn high income from rubber and fatten 1.9 ±1.80 pigs per household (HH), often using purchased pig feed at markets. PB farms own similar sized rubber plantations and raise 4.7 ±2.77 pigs per HH, with fodder mainly being cultivated and collected in theforest. LB farms grow corn, rice and tea and keep 4.6 ±3.32 pigs per HH, also fed with collected and cultivated fodder. Only 29% of all pigs were marketed (LB: 20%; RB: 42%; PB: 25%), average annual mortality was 4.0 ±4.52 pigs per farm (LB: 4.6 ±3.68; RB: 1.9 ±2.14; PB: 7.1 ±10.82). Pig feed mainly consists of banana pseudo stem, corn and rice hives and is prepared in batches about two to three times per week. Such fodder might be sufficient in energy content but lacks appropriate content of protein. Pigs therefore suffer from malnutrition, which becomes most critical in the time before harvest season around October. Farmers reported high occurrences of gastrointestinal parasites in carcasses and often pig stables were wet and filled with manure. Deficits in nutritional and hygienic management are major limits for development and should be the first issues addressed to improve productivity. SME pork was found to be known and referred by local customers in town and by richer lowland farmers. However, high prices and lacking availability of SME pork at local wet-markets were the reasons which limited purchase. If major management constraints are overcome, pig breeders (PB and LB farms) could increase the share of marketed pigs for town markets and provide fatteners to richer RB farmers. RB farmers are interested in fattening pigs for home consumption but do not show any motivation for commercial pig raising. To determine the productivity of input factors in pig production, eproductive performance, feed quality and quantity as well as weight development of pigs under current management were recorded. The data collection included a progeny history survey covering 184 sows and 437 farrows, bi-weekly weighing of 114 pigs during a 16-months time-span on 21 farms (10 LB and 11 PB) as well as the daily recording of feed quality and quantity given to a defined number of pigs on the same 21 farms. Feed samples of all recorded ingredients were analyzed for their respective nutrient content. Since no literature values on thedigestibility of banana pseudo stem – which is a major ingredient of traditional pig feed in NRNNR – were found, a cross-sectional digestibility trial with 2x4 pigs has been conducted on a station in the research area. With the aid of PRY Herd Life Model, all data have been utilized to determine thesystems’ current (Status Quo = SQ) output and the productivity of the input factor “feed” in terms of saleable life weight per kg DM feed intake and monetary value of output per kg DM feed intake.Two improvement scenarios were simulated, assuming 1) that farmers adopt a culling managementthat generates the highest output per unit input (Scenario 1; SC I) and 2) that through improved feeding, selected parameters of reproduction are improved by 30% (SC II). Daily weight gain averaged 55 ± 56 g per day between day 200 and 600. The average feed energy content of traditional feed mix was 14.92 MJ ME. Age at first farrowing averaged 14.5 ± 4.34 months, subsequent inter-farrowing interval was 11.4 ± 2.73 months. Littersize was 5.8 piglets and weaning age was 4.3 ± 0.99 months. 18% of piglets died before weaning. Simulating pig production at actualstatus, it has been show that monetary returns on inputs (ROI) is negative (1:0.67), but improved (1:1.2) when culling management was optimized so that highest output is gained per unit feed input. If in addition better feeding, controlled mating and better resale prices at fixed dates were simulated, ROI further increased to 1:2.45, 1:2.69, 1:2.7 and 1:3.15 for four respective grower groups. Those findings show the potential of pork production, if basic measures of improvement are applied. Futureexploration of the environment, including climate, market-season and culture is required before implementing the recommended measures to ensure a sustainable development of a more effective and resource conserving pork production in the future. The two studies have shown that the production of local SME pigs plays an important role in traditional farms in NRNNR but basic constraints are limiting their productivity. However, relatively easy approaches are sufficient for reaching a notable improvement. Also there is a demand for more SME pork on local markets and, if basic constraints have been overcome, pig farmers could turn into more commercial producers and provide pork to local markets. By that, environmentally safe meat can be offered to sensitive consumers while farmers increase their income and lower the risk of external shocks through a more diverse income generating strategy. Buffaloes have been found to be the second important livestock species on NRNNR farms. While they have been a core resource of mixed smallholderfarms in the past, the expansion of rubber tree plantations and agricultural mechanization are reasons for decreased swamp buffalo numbers today. The third study seeks to predict future utilization of buffaloes on different farm types in NRNNR by analyzing the dynamics of its buffalo population and land use changes over time and calculating labor which is required for keeping buffaloes in view of the traction power which can be utilized for field preparation. The use of buffaloes for field work and the recent development of the egional buffalo population were analyzed through interviews with 184 farmers in 2007/2008 and discussions with 62 buffalo keepers in 2009. While pig based farms (PB; n=37) have abandoned buffalo keeping, 11% of the rubber based farms (RB; n=71) and 100% of the livestock-corn based farms (LB; n=76) kept buffaloes in 2008. Herd size was 2.5 ±1.80 (n=84) buffaloes in early 2008 and 2.2 ±1.69 (n=62) in 2009. Field work on own land was the main reason forkeeping buffaloes (87.3%), but lending work buffaloes to neighbors (79.0%) was also important. Other purposes were transport of goods (16.1%), buffalo trade (11.3%) and meat consumption(6.4%). Buffalo care required 6.2 ±3.00 working hours daily, while annual working time of abuffalo was 294 ±216.6 hours. The area ploughed with buffaloes remained constant during the past 10 years despite an expansion of land cropped per farm. Further rapid replacement of buffaloes by tractors is expected in the near future. While the work economy is drastically improved by the use of tractors, buffaloes still can provide cheap work force and serve as buffer for economic shocks on poorer farms. Especially poor farms, which lack alternative assets that could quickly be liquidizedin times of urgent need for cash, should not abandon buffalo keeping. Livestock has been found to be a major part of small mixed farms in NRNNR. The general productivity was low in both analyzed species, buffaloes and pigs. Productivity of pigs can be improved through basic adjustments in feeding, reproductive and hygienic management, and with external support pig production could further be commercialized to provide pork and weaners to local markets and fattening farms. Buffalo production is relatively time intensive, and only will be of importance in the future to very poor farms and such farms that cultivate very small terraces on steep slopes. These should be encouraged to further keep buffaloes. With such measures, livestock production in NRNNR has good chances to stay competitive in the future.

Compositional ideas in the bayesian analysis of categorical data with application to dose finding clinical trials

Compositional random vectors are fundamental tools in the Bayesian analysis of categorical data. Many of the issues that are discussed with reference to the statistical analysis of compositional data have a natural counterpart in the construction of a Bayesian statistical model for categorical data. This note builds on the idea of cross-fertilization of the two areas recommended by Aitchison (1986) in his seminal book on compositional data. Particular emphasis is put on the problem of what parameterization to use

Análisis del Espacio Schengen en materia de seguridad como base para la implementación del Protocolo sobre la Facilitación del Movimiento de Personas de la Comunidad para el Desarrollo de África Austral (SADC)

El fin de la Guerra Fría supuso no sólo el triunfo del capitalismo y de la democracia liberal, sino un cambio significativo en el Sistema Internacional; siendo menos centralizado y más regionalizado, como consecuencia de la proximidad y relaciones de interdependencia entre sus actores (no sólo Estados) y permitiendo la formación de Complejos Regionales de Seguridad (CRS). Los CRS son una forma efectiva de relacionarse y aproximarse a la arena internacional pues a través de sus procesos de securitización y desecuritización consiguen lograr objetivos específicos. Partiendo de ello, tanto la Unión Europea (UE) como la Comunidad para el Desarrollo de África Austral (SADC) iniciaron varios procesos de securitización relacionados con la integración regional; siendo un ejemplo de ello la eliminación de los controles en sus fronteras interiores o libre circulación de personas; pues consideraron que de no hacerse realidad, ello generaría amenazas políticas (su influencia y capacidad de actuación estaban amenazadas), económicas (en cuanto a su competitividad y niveles básicos de bienestar) y societales (en cuanto a la identidad de la comunidad como indispensable para la integración) que pondrían en riesgo la existencia misma de sus CRS. En esta medida, la UE creó el Espacio Schengen, que fue producto de un proceso de securitización desde inicios de la década de los 80 hasta mediados de la década de los 90; y la SADC se encuentra inmersa en tal proceso de securitización desde 1992 hasta la actualidad y espera la ratificación del Protocolo para la Facilitación del Movimiento de personas como primer paso para lograr la eliminación de controles en sus fronteras interiores. Si bien tanto la UE como la SADC consideraron que de no permitir la libre circulación de personas, su integración y por lo tanto, sus CRS estaban en riesgo; la SADC no lo ha logrado. Ello hace indispensable hacer un análisis más profundo de sus procesos de securitización para así encontrar sus falencias con respecto al éxito de la UE. El análisis está basado en la Teoría de los Complejos de Seguridad de Barry Buzan, plasmada en la obra Security a New Framework for Analysis (1998) de Barry Buzan, Ole Waever y Jaap de Wilde y será dividido en cada una de las etapas del proceso de securitización: la identificación de una amenaza existencial a un objeto referente a través de un acto discursivo, la aceptación de una amenaza por parte de una audiencia relevante y las acciones de emergencia para hacer frente a las amenazas existenciales; reconociendo las diferencias y similitudes de un proceso de securitización exitoso frente a otro que aún no lo ha sido.

Analysis of the alveolar recruitment maneuvers applied at seven intensive care units

Introduction: During the past years, alveolar recruitment maneuvers (RM) have produced growing interest due to their beneficial potential in pulmonary protection, and have been introduced in clinical practice. Objective: To describe and analyze the knowledge of MR and its application at seven intensive care units in the city of Cali, Colombia. Methods and materials: Descriptive Cross-Sectional Study with an intentional sample of 64 professionals working in seven intensive care units and who apply MR. The self-completed survey was made up of thirteen questions, and the application period was two months. Results: Out of 64 professionals surveyed, 77.8% of them follow a protocol guide; 54.7% employes during RM the ideal Positive end-expiratory pressure (PEEP), which maintains a saturation > 90% and a PaO2 > 60 mmHg; 42.1% tolerates airway pressures between 35 and 50 cmH2O; 48.4% perform RM with a progressive increase of the PEEP and a low tidal volume. Conclusions: Regarding the knowledge related to RM, heterogeneity was found in the answers. There is currently no consensus about which is the most effective and secure way to implement an MR. This study can be the starting point to create awareness towards the revision of knowledge, capacities and abilities that are required to perform RM.

Description and analysis of pulmonary rehabilitation care programs current state in four cities of Colombia

Purpose: there are many studies reporting the benefits of pulmonary rehabilitation, but few of them exhibit the behavior and activities of these services. This article presents the characteristics of services, parts management and training level of team members, in addition to the variables or instruments used to measure the effectiveness and impact in these programs. Method: it was made a cross sectional convenience sample which included seven pulmonary rehabilitation services in four Colombian cities (Bogotá, Medellín, Manizales and Cali), selected by the coverage, for having at least one year of experience and for being formally established and recognized nationwide. The interdisciplinary team of each service answered a survey that was validated through a pilot test and expert consensus. Participation was voluntary. Results: labor onset pulmonary rehabilitation services correspond to an average of a decade, with COPD and asthma pathologies of attention. The programs are characterized by an outpatient treatment with an average duration of eight to twelve weeks, with a frequency of an hour three times a week. Also, the director of the service is regularly a pulmonologist and the coordinator a physiotherapist (57.14%). The posgradual training of these professionals is notable, and they report to have procedural, administrative and communicative skills, but qualify regular there research skills. The physical and technological resources are well tested. 71.42% have done impact studies, but only 28.57% have been published. All have in common training in upper limbs, lower limbs, respiratory muscles, counseling, functional assessment and quality of life. The effectiveness and impact of programs is measured by the walking test, quality of life questionnaires and activities of daily living.

International Organizations: Fostering Democracy “at Home”: From Silent Players to Salient Players?

The international dimension of democratisation is a major concern in the study of contemporary political systems. The analysis of domestic political transformations in which International Organisations (IOs) may be salient actors compromises the traditional inward-looking approach of comparative politics that holds democracy to be a domestic affair par excellence. Nevertheless, the maturity of any process of democratisation relies upon the establishment and sustainability of institutions that genuinely reflect the interests and socio-political identity of the citizens of that polity. The role of external influence, whether progressive or abrupt, is clearly limited in constructing and sustaining this process. However, the relevance of international variables in influencing the renaissance or enhancement of democracy has not been overlooked by either scholars or politicians over the past fifteen years. As a number of political systems went through what became known as the third wave of democratization, the role of IOs in breaking down undemocratic strongholds and in neutralising possible reversals began to gain momentum. Contending approaches and controversial case studies alike appear to elicit very different conclusions concerning the legitimacy and the effectiveness of international actors in this field. This analysis addresses the rationale underpinning the deployment of multilateral external actors as agents of democratisation. Drawing on an integrative theoretical approach and a comparative case study involving the democratisation agendas of the Organization of American States (OAS) and the United Nations (UN) in Latin America (LA), contrasting international models of deployment are assessed. It is argued that IOs’ democratisation strategies are based on institutional roadmaps leading towards the attainment of targets which vary according to three key ´guidelines’: how democracy is conceptualised, what cooperative strategies are used, and what frameworks for democratisation are adopted.-----La dimensión internacional de la democratización representa un fenómeno importante de los sistemas políticos contemporáneos. El hecho de que la transformación política interna sea incluida bajo el título de organizaciones internacionales (OI) indica un rompimiento con el enfoque tradicional de observación interna de la política comparativa, si se parte de la suposición de que la “democracia” es un asunto interno por excelencia. Hay procesos complejos que limitan la viabilidad de la fortuna democrática en la política interior, los cuales dependen de las estructuras representativas del poder que fluye de la legitimidad nacional y la identidad política. No obstante, los estímulos internacionales que sostienen a los sistemas nacionales de gobierno, estructurados alrededor de la construcción y la consolidación de la democracia, están en el centro de la política comparativa contemporánea. Cuando varios sistemas políticos atravesaban la tercera ola de democratización, las OI asumieron rápidamente una posición significativa como agentes que neutralizaban los miedos a la inversión de políticas, rompiendo lazos con formas antidemocráticas de gobierno y eliminando las normas informales de los juegos democráticos. Las dinámicas mencionadas dan fundamento para abordar el debate sobre los modelos externos de apoyo. Mediante un enfoque teórico integrador y un estudio comparativo de casos de las agendas de democratización de la Organización de Estados Americanos y las Naciones Unidas dirigidas a la problemática democrática latinoamericana, se aclaran modelos internacionales “ocultos” de despliegue. Se argumenta que las estrategias de las OI para democratizar se fundamentan en que los planes de desarrollo institucionales para la democratización lleguen a los objetivos democráticos a través de tres “guías” multilaterales: conceptualización de la democracia, estrategias de cooperación y marcos de referencia especiales para la democratización.

An analysis of the relationship between wages in the public and private sector in colombia : a panel data approach

This document examines the time-series properties of the wage differentials that arise between the public and private sector in Colombia during the sample period 1984 to 2005. We Find conflicting results in unit-root and stationary tests when looking at wage differentials at an aggregate level (such as for men, women or both). However, when we analyse wage differentials at higher levels of disaggregation, treat them jointly as a panel of data, and allow for the presence of potential cross section dependence, there is more supportive evidence for the view that wage differentials are stationary. This implies that although wage differentials do exist, they have not been consistently increasing (or decreasing) over time.

The persistent colombian conflict bubnational analysis of the duration of violence

The growing empirical literature on the analysis of civil war has recently included the study of conflict duration at the cross-country level. This paper presents, for the first time, a within-country analysis of the determinants of violence duration. I focus on the experience of the Colombian armed conflict. While the conflict has been active for about five decades, local violence ebbs and flows and areas experiencing continuous conflict coexist with places that have been able to resile and where violence is mostly absent. I examine a wide range of factors potentially associated with violence duration at the municipal level, including scale variables, geographical conditions, economic and social variables, institutions and state presence, inequality, government intervention, and victimization variables. I characterize a few variables robustly correlated with the persistence of localized conflict, both across specifications and using different econometric models of duration analysis.

Overcoming Gender Disadvantages. Social Policy Analysis of urban middle-class women in Colombia

The World Bank Report 2012 starts with this statement: “Gender equality matters in itself andit matters for development because, in today’s globalized worlds, countries that use the skillsand talents of their women would have an advantage over those which do not use it.” With theframe that suggest that gender equality matters, this paper describes some policy alternativesoriented to overcome gender disadvantages in the formal labor market incorporation of theurban middle class women in Colombia. On balance, the final recommendation suggest that itis desirable to adopt policy alternatives as Community Centers, which are programs orientedto a social redistribution of the domestic work as a way to encourage women participationin the formal labor market with the social support of the members of their own community.The problem that the social policy needs to address is the segregation of women in the formallabor market in Colombia. Although the evidence shows that the women overcome theeducational gap by showing better performance in education that their male peers, womenare still segregated of the labor market. The persistence of high rates of unemployment on thefemale population, the prevalence of the informal labor market as a women labor market, andthe presence of the payment difference between men and women with similar professionaltrainings are circumstances that sustain the segregation statement. These circumstances areinefficient for the society because an economic analysis shows that the cost of maintain the statuquo is externalized in the social security system that includes health, pension and maternityleave regimens. Therefore, the women segregation involves a market failure.This paper evaluates five policy alternatives each directed to the progress of a different causaldimension of the problem: (i) Quotas in the private market, (ii) Flexible working hours,(iii) replace the maternity leave with a family leave, (iv) Increase the Community Centers forredistributing the care work, and (v) Equal payment enforcement. The first alternative looksto increase women’s participation in the formal labor market. The second, third, and fourthalternatives constitute a package addressed at redistributing care work by reducing women’sresponsibility for reproductive work in the household with the help of husbands and the localgovernment. The fifth alternative intervenes to resolve the equal payment problem.After a four criteria evaluation that measure effectiveness, robustness and improbability inimplementation, efficiency and political acceptability or social opposition, the strongest alternativeis the fostering of Community Centers that promote a redistribution of care work. Thispolicy performs well in the assessment process because it combines gender focus with importantindirect effects: child support and human capabilities. The policy also shows a bottomup implementation process that overcomes the main adoption difficulties in the gender focusprograms and is supported by strong evidence of success in the Colombian context; this evidenceis produced by both transnational actors as a World Bank and also in local accountabilityreporters executed by local institutions like Colombian Institute of Family Welfare (ICBF).

Entrepreneurship, ties and relational networks: the case of a public-private cross-border tourism product

The thesis aims to understand the processes of entrepreneurship that try to create businesses or products with a high degree of complexity. This complexity comes from the fact that these products or initiatives can only be viable with the concurrence of a large number of heterogeneous actors (public, private, from different regions, etc..) which interact in a relational context. A case with these characteristics is the Camí dels Bons Homes. The thesis analyzes the evolution of the relational network from the point of view of its structure and content of its links. The results show and explain the observed changes in the network structure and the changes in the ties content. This analysis of the content of ties contributes to a new systematization and operationalization of ties’ content. Moreover this analysis takes in account negative ties, a less discussed issue in literature.

A comparison of cross-hole electrical and seismic data in fractured rock

Cross-hole anisotropic electrical and seismic tomograms of fractured metamorphic rock have been obtained at a test site where extensive hydrological data were available. A strong correlation between electrical resistivity anisotropy and seismic compressional-wave velocity anisotropy has been observed. Analysis of core samples from the site reveal that the shale-rich rocks have fabric-related average velocity anisotropy of between 10% and 30%. The cross-hole seismic data are consistent with these values, indicating that observed anisotropy might be principally due to the inherent rock fabric rather than to the aligned sets of open fractures. One region with velocity anisotropy greater than 30% has been modelled as aligned open fractures within an anisotropic rock matrix and this model is consistent with available fracture density and hydraulic transmissivity data from the boreholes and the cross-hole resistivity tomography data. However, in general the study highlights the uncertainties that can arise, due to the relative influence of rock fabric and fluid-filled fractures, when using geophysical techniques for hydrological investigations.

Tracer correlations in the northern high latitude lowermost stratosphere: Influence of cross‐tropopause mass exchange

We present an analysis of trace gas correlations in the lowermost stratosphere. In‐situ aircraft measurements of CO, N2O, NOy and O3, obtained during the STREAM 1997 winter campaign, have been used to investigate the role of cross‐tropopause mass exchange on tracer‐tracer relations. At altitudes several kilometers above the local tropopause, undisturbed stratospheric air was found with NOy/NOy * ratios close to unity, NOy/O3 about 0.003–0.006 and CO mixing ratios as low as 20 ppbv (NOy * is a proxy for total reactive nitrogen derived from NOy–N2O relations measured in the stratosphere). Mixing of tropospheric air into the lowermost stratosphere has been identified by enhanced ratios of NOy/NOy * and NOy/O3, and from scatter plots of CO versus O3. The enhanced NOy/O3 ratio in the lowermost stratospheric mixing zone points to a reduced efficiency of O3 formation from aircraft NOx emissions.