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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Restauração de dentes tratados endodonticamente: ensaio clínico randomizado e revisão sistemática com metánalise / Restoration of endodontically treated teeth: a randomized clinical trial and a systematic review with meta-analysis

Onofre, Rafael Sarkis 13 December 2012 (has links)
Made available in DSpace on 2014-08-20T14:30:09Z (GMT). No. of bitstreams: 1 Dissertacao_rafael_sarkis_onofre.pdf: 1491340 bytes, checksum: 00453dc2916d638be0bec47f9d29aa11 (MD5) Previous issue date: 2012-12-13 / The best way to restore endodontically treated teeth has been discussed in the literature because some factors can influence the post selection and the final restoration. Two of the most used intra-radicular posts are cast metal posts and glass fiber posts. Moreover, there is a large variability of in vitro studies that evaluate the use of different resin cement and the alterations of technique and the influence in the bond strength of glass fiber posts. The aims of the study were to compare the survival of two types of dental posts used to restore endodontically treated teeth with great damage of coronal walls and verify through a systematic review if there is difference on bond strength of glass fiber posts to dentin between self-adhesive and regular resin cements. Systematic review: In vitro studies that investigated the bond strength of glass fiber post luted with self-adhesive (RC) and regular (RC) were selected. Global comparison between self-adhesive (RC) and regular resin cement was performed. Two subgroup analyses were performed: self-adhesive resin cement x regular resin cement (etch-and-rinse adhesive), self-adhesive resin cement x regular resin cement (self-etch adhesive). The three analyses performed showed favorable results to self-adhesive resin cement. Clinical trial: The teeth were randomly allocated into two groups depending on the post used: glass fiber or cast metal post. Fifty-four (45 women) patients and 72 teeth were evaluated up to 3 years and the survival probabilities were 97.1% and 91.9% to cast metal posts and glass fiber posts. Four failures were observed, 2 glass fiber posts debonding (premolar and anterior tooth), 1 glass fiber post debonding associate with root fracture and 1 root fracture with a cast metal post. We can conclude that in vitro literature seems to suggest that the use of self-adhesive cement could help to achieve higher bond strength of GFPs to the root canal and after 3 years of follow up, both posts presented the same clinical performance and / A melhor maneira de se restaurar dentes tratados endodonticamente vem sendo muito discutida na literatura principalmente porque alguns fatores como a escolha do pino a ser utilizado pode influenciar o resultado final da restauração. Dois dos retentores intra-radiculares mais utilizados atualmente são os núcleos metálicos fundidos e os pinos de fibra de vidro. Além disso, existe uma grande variabilidade de estudos in vitro que avaliam tanto a utilização de diferentes cimentos resinosos como alterações das técnicas e a influência na resistência de união de pinos de fibra de vidro. O objetivo deste trabalho foi avaliar as taxas de sucesso clínico de dentes tratados endodonticamente sem remanescente coronário e restaurados com de pino de fibra de vidro ou núcleo metálico fundido através de um ensaio clínico randomizado. Além disso, realizar uma revisão sistemática da literatura de ensaios in vitro que comparassem a resistência de união de pinos de fibra de vidro cimentados com cimento resinoso regular e cimento resinoso autoadesivo. Para a revisão sistemática, estudos in vitro que avaliaram a resistência de união de pinos de fibra de vidro cimentados com cimento autoadesivo e cimento regular foram selecionados. As seguintes metánalises foram realizadas: comparação global entre cimento autoadesivo x cimento regular e análises de subgrupo cimento autoadesivo x cimento regular (adesivo etch-and-rinse) e cimento autoadesivo x cimento regular (adesivo self-etch). As três análises mostraram resultados estatisticamente significantes e favorecendo o uso de cimento autoadesivo. No ensaio clínico, os dentes selecionados foram randomizados e alocados em 2 grupos dependendo do pino utilizado. Após 3 anos, 54 pacientes (72 dentes: 35 núcleos metálicos fundidos e 37 pinos de fibra de vidro) foram avaliados. As taxas de sobrevivência foram 97,1% e 91,9% para núcleos metálicos fundidos e pinos de fibra de vidro respectivamente. Quatro falhas foram observadas: duas descimentações de pinos de fibra de vidro (pré-molar e dente anterior), uma descimentação de pino de fibra de vidro associada a fratura radicular (pré-molar) e uma fratura radicular associada ao uso de núcleo metálico fundido (molar). Conclui-se que a literatura sugere que o uso de cimento resinoso autoadesivo poderia ajudar a conseguir maior resistência de pinos de fibra vidro ao canal radicular e que após 3 anos, ambos os pinos apresentaram performance semelhante
102

Uso de materiais diretos e indiretos para amplas restaurações: implicações clínicas e laboratoriais / Use of direct and indirect materials for extensive restorations: clinical and laboratory implications

Skupien, Jovito Adiel 14 March 2014 (has links)
Made available in DSpace on 2014-08-20T14:30:19Z (GMT). No. of bitstreams: 1 Tese_Jovito_Adiel_Skupien.pdf: 8297294 bytes, checksum: 72ce694b2bb9e499cf0353c4c4b8df4e (MD5) Previous issue date: 2014-03-14 / Glass fiber posts and composite resins are widely used materials in restorative dentistry. The various forms of presentation and technical approach, as well as different handling prior to their use, can result in diverse outcomes, which can determine the success or failure of the restorative procedure. Thus, the aim of this study was to evaluate the performance of glass fiber posts and composite resins in front of several factors related to it uses in dentistry. For this, the study was divided into three parts: An in vitro study, an in vivo study and a systematic review. The in vitro study aimed to evaluate the effect of cementation delay of indirect composite resin restorations in previously hybridized dentin. Three strategies of cementation were tested through different protocols. Beam-shaped specimens from tooth/restoration were obtained and submitted to microtensile testing to evaluate the bond strength and types of failures, where the results were analyzed by ANOVA and Tukey s post hoc tests and linear regression. Regular cement and adhesive threestep etch-and-rinse adhesive system showed the highest values of bond strength, followed by the same cement and two-step etch-and-rinse adhesive system and the lowest values for self-adhesive cement groups. Linear regression showed an improvement in the bond strength values when three-step adhesive system was used, however, all groups had adequate values of bond strength, even in unfavorable situations. The randomized clinical trial evaluated the longevity of metal-ceramic crown and composite resin restorations performed in endodontically treated teeth that received a glass fiber post. Fifty-six severely damaged teeth but with at least one entire wall were randomly allocated into two groups according to the type of restoration. The longevity was assessed through Kaplan-meier and clinical evaluation by descriptive analysis. The recall rate was 100%, fifty-six teeth were re-evaluated with no absolute failure. However, eight composite resin restorations had failed (all reparable). A significant difference between type of restoration was found. Indirect restorations provided higher acceptable clinical performance after two-year of followup, although composite failures were liable to repair. The systematic review compared factorts that can influence retention of glass fiber posts to intraradicular based on in vitro studies which compared the bond strength of resin cements. Searches were carried out in Pubmed and Scopus database up to December 2013. Thirty-four studies were included in the review and several variables were extracted. The presence of endodontic treatment significantly decrease the bond strength, meanwhile other variables can influence according to the type of resin cement. Thus, factors as type of cement application and pretreatment of post can influence glass fiber post retention, however, self-adhesive resin cements are less sensitive to luting procedures / Pinos de fibra de vidro e resinas compostas são materiais amplamente utilizados em odontologia restauradora. As diferentes formas de apresentação e técnicas de emprego, bem como diferentes manobras prévias às suas utilizações podem implicar em desfechos clínicos mais ou menos favoráveis, que podem determinar o sucesso ou falha de um procedimento restaurador. Assim, o objetivo deste estudo foi avaliar o desempenho de pinos de fibra de vidro e resinas compostas frente a diversos fatores relacionados ao seu uso em odontologia. Para isso, o estudo foi dividido em três partes: estudo in vitro, estudo in vivo e revisão sistemática. O estudo in vitro objetivou avaliar o efeito do retardamento da cimentação de restaurações indiretas de resinas compostas em dentina previamente hibridizada. Três estratégias de cimentação foram testadas com diferentes protocolos. Palitos do conjunto dente/restauração foram obtidos e submetidos ao teste de microtração para avaliação da resistência de união e padrão de fratura, onde os valores foram analisados através de ANOVA e teste post hoc Tukey (!=0,05) e regressão linear. Cimento convencional e sistema adesivo de 3 passos apresentaram os maiores valores de resistência de união, seguidos do mesmo cimento e sistema de 2 passos, sendo os menores valores para o grupo do cimento auto-adesivo. A regressão linear demonstrou uma melhora significativa nos valores de resistência quando o sistema de 3 passos foi utilizado, entretanto, todos os grupos tiveram resultados adequados, mesmo em condições desfavoráveis. O ensaio controlado randomizado avaliou a longevidade de restaurações metalo-cerâmicas e de resinas compostas confeccionadas em dentes tratados endodonticamente que receberam um pino de fibra de vidro. Cinqüenta e seis dentes com a coroa danificada, porém, com uma face intacta, foram alocados em dois grupos aleatoriamente, de acordo com o tipo de restauração. A longevidade das restaurações foi avaliadas através de Kaplan- Meier e critérios clínicos foram analisados de forma descritiva. Com uma taxa de rechamada de 100%, 56 dentes foram reavaliados e nenhum foi perdido. Porém, 8 restaurações de resina composta falharam e sofreram reparos. Houve uma diferença significativa para o tipo de restauração em relação ao sucesso. Assim, restaurações indiretas apresentaram uma melhor performance clínica após 2 anos de acompanhamento, embora as falhas apresentadas no grupo que recebeu resinas diretas tenham sido reparáveis. A revisão sistemática comparou fatores que podem influenciar na retenção de pinos de fibra de vidro em dentina intra-radicular baseado em estudos in vitro que compararam a resistência de união de cimentos resinosos. Após uma busca realizada nos bancos de dados Pubmed e Scopus até dezembro de 2013, trinta e quatro estudos foram incluídos na revisão e diferentes variáveis foram extraídas. A presença de tratamento endodôntico diminuiu significativamente a resistência de união, enquanto que demais variáveis variam sua influência de acordo com o tipo de cimento resinoso. Assim, fatores como método de aplicação do cimento e pré-tratamento do pino podem influenciar a retenção de pinos de fibra de vidro, porém, cimentos auto-adesivos são menos sensíveis à técnica de cimentação
103

Gritos en el Desierto: Denuncia y Resistencia en las Obras de las Escritoras Wayuu Estercilia Simanca Pushaina y Vicenta Marí­a Siosi Pino

Perwak, Lindsay H. 02 June 2016 (has links)
The way we read and interpret literature is frequently influenced by factors that operate beyond the scope of the average reader's awareness. In this thesis, selected works by two Wayuu writers, Estercilia Simanca Pushaina and Vicenta Maria Siosi Pino, are analyzed and interpreted in an attempt to unveil some of these behind-the-scenes agents and issues, as well as explore how the stories' classification in the children's literature genre reveals a deep-rooted colonial tendency to infantilize indigenous individuals in contemporary Colombia. Despite the fact that the two authors, both mestizo women who self-identify with the Wayuu indigenous group of northern Colombia, prefer to write short stories that highlight the child and adolescent experience, the implicit themes and the complexity of their texts reject the "children's story" label that has been imposed on their literature. Furthermore, this thesis discusses how the two authors utilize the colonial trope of the Indian-as-child to their advantage by capsizing the imagery, thus rejecting the original power of the symbol and claiming it as their own. The first section of this investigation provides certain contextual specifics related to the cultural and social environment of the Wayuu indigenous group, particularly regarding that experienced by women. The second chapter includes an explanation of the impact a book's genre and its "paratext" may have on the reception and interpretation of these texts, and additionally proposes that the colonial practice of infantilizing indigenous people appears in both the assignment of genre as well as in several extratextual elements surrounding the stories. Chapter three offers an in-depth analysis of five selected pieces of the Wayuu authors' writing and explores how the texts may be read on multiple levels. This close reading reveals several examples of overt criticism towards the hegemonic society as well as displays instances of a more subtle rebellion; both explicit and implicit messages effectively expose and protest the current conditions of abuse, oppression and injustice that continue to anguish the Wayuu people.
104

Wachstumsmodell für die Karibische Kiefer (Pinus caribaea Morelet var. hondurensis [Sénéclauze]) in der Dominikanischen Republik: Wachstumsmodell für die Karibische Kiefer (Pinus caribaea Morelet var. hondurensis [Sénéclauze]) in der Dominikanischen Republik

Körner, Michael 03 August 2015 (has links)
Die nachhaltige Bewirtschaftung des Waldes stellt eine der wichtigsten Anforderungen an das forstwirtschaftliche Handeln dar. In diesem Kontext befasst sich die vorliegende Arbeit mit der modellhaften Abbildung des Einzelbaumwachstums der Baumart Pinus caribaea var. hondurensis und bildet damit die Grundlage zur Entwicklung nachhaltiger Bewirtschaftungskonzepte in der Dominikanischen Republik. Die Datenbasis für die Berechnung von Ertragskennwerten und für die sich anschließende Modellierung beruht auf der Anlage von 30 Probeflächen, die in den Jahren 2008, 2009 und 2010 aufgenommen wurden. 16 Probeflächen entfallen dabei auf die Region Jarabacoa und 14 Probeflächen auf die Region Restauración. Nach der Markierung der Probeflächen und der Einzelbäume wurden u.a. der Durchmesser d1,3, die Baumhöhen h, die Kronenbreite kb, der Kronenansatz ka sowie die Baumpositionen erfasst. Aus diesen Messwerten konnten zunächst Ertragskenngrößen berechnet werden. Das Bestandesalter t deckt hierbei einen Bereich von 3 bis 38 Jahren ab. Der Mitteldurchmesser dg variiert zwischen einem Minimalwert von 8,1 cm und einem Maximum von 38,4 cm. Des Weiteren konnten für alle Aufnahmen Mittelhöhen hg mit Werten von 6,7 m bis 33,7 m ermittelt werden. Die Grundfläche G nimmt Werte zwischen 11,3 m² und 63,0 m² an. Aufbauend auf den Ergebnissen der Basisauswertung und dem Einzelbaumwachstumssimulator BWINPro (NAGEL 1999) wurde anschließend ein regionales Wachstumsmodell angepasst. Zu diesem Zweck waren insbesondere Änderungen in den Bereichen der Datenergänzung, der Zuwachsprognose und zur Nachbildung der Mortalität notwendig, wobei sich an der vorhandenen Modellstruktur orientiert wurde. Im Bereich des Datenergänzungsmoduls war die Anpassung von Funktionen zur Erzeugung einer Durchmesserliste und zur Generierung von Einzelbaumhöhen notwendig. Die Erzeugung einzelner Durchmesser erfolgte auf der Basis der Weibull-Verteilung und linearer Gleichungen, die den Maßstabsparameter b und den Formparameter c dieser Verteilung beschreiben. In diesem Zusammenhang kamen die Prädiktoren Mitteldurchmesser dg und Maximaldurchmesser dmax zum Einsatz. Zur Generierung von Einzelbaumhöhen wurden zwei Einheitshöhenkurvenmodelle angepasst und auf ihre Eignung hin verglichen. Das Modell von SLOBODA et al. (1993) erwies sich gegenüber dem Modell, das von ARCANGELI et al. (2013) verwendet wurde, als besser geeignet. Zur Erzeugung einer gewissen Höhenvariation bei den generierten Einzelbaumhöhen wurde zudem ein Modell in Anlehnung an ALBERT (2000) angepasst. Zur Berechnung der Standardabweichung der Höhenresiduen um die Bestandeshöhenkurve nach MICHAILOFF (1943) erscheint in diesem Zusammenhang das Modell mit der unabhängigen Variable dg als geeignet. Kronenbreiten- und Kronenansatzfunktionen werden sowohl im Bereich der Datenergänzung als auch in der Zuwachsprognose benötigt. Bei der Ermittlung eines geeigneten Kronenansatzmodells wurde auf die Funktionen von SCHMIDT (2001), VAN DEUSEN und BIGING (1985) sowie auf die Funktion von PRETZSCH (2001) zurückgegriffen. Die Funktion von SCHMIDT (2001), die auch in der niedersächsischen Version von BWINPro verwendet wird, weist die beste Anpassung an das Datenmaterial auf. In die Findung einer passenden Kronenbreitenfunktion wurden die Modelle aus den Wachstumssimulatoren Silva (PRETZSCH 2001) und BWINPro (DÖBBELER et al. 2011) einbezogen. Hierbei erwies sich die Funktion aus Silva als besser geeignet. Für die Anpassung der Zuwachsprognose der Baumart P. caribaea var. hondurensis unter den Wuchsbedingungen in der Dominikanischen Republik mussten Funktionen zur Berechnung des Durchmesser- und Höhenzuwachses aktualisiert werden. Das Durchmesserzuwachsmodell beruht hierbei weitestgehend auf dem Ansatz von NAGEL (1999). Als unabhängige Variablen wurden die Kronenmantelfläche km, das Bestandesalter t und der positionsunabhängige Konkurrenzindex C66 nach WENSEL et al. (1987) verwendet. Die Berechnung erfolgte ausschließlich unter Einbeziehung von Bäumen, von denen der Durchmesser d1,3, die Baumhöhe h sowie die Kronenbreite kb und der Kronenansatz ka als Messwerte zur Verfügung standen. Aufgrund dieser Einschränkung umfasste der Stichprobenumfang lediglich 475 Bäume. Mit einem adjustierten Bestimmtheitsmaß von 0,6409 wurde im Vergleich zu anderen Untersuchungen dennoch ein gutes Anpassungsergebnis erzielt. Eine direkte Schätzung von Einzelbaumhöhenzuwächsen analog zur Durchmesserzuwachsschätzung konnte aufgrund fehlender Höhenzuwächse nicht realisiert werden. Aus diesem Grund wird hierfür ein Verfahren zur Berechnung von Höhenzuwächsen auf der Basis von Einheitshöhenkurven empfohlen. Die Umsetzung des Ansatzes kann in Anlehnung an den Ansatz von KAHN und ĎURSKÝ (1999) erfolgen. Die Voraussetzung zur Verwendung dieses Ansatzes stellt ein Einheitshöhenkurvenmodell und ein Modell zur Beschreibung der Bestandeshöhenentwicklung dar. Um Konsistenz zwischen beiden notwendigen Modellen herzustellen, erfolgte die Parametrisierung auf der Basis der Oberhöhe h100 und des Oberdurchmessers d100. Durch die Verwendung dieser Werte sind die Funktionen zudem stabiler gegenüber Durchforstungen. Für die Anpassung einer Alters-Höhen-Kurve zur Beschreibung der Oberhöhenentwicklung wurden verschiedene Wachstumsfunktionen getestet. Hierzu zählen die CHAPMAN-RICHARDS-Funktion (RICHARDS 1959), die Funktionen von GOMPERTZ (1825), KORF (1939), SCHUMACHER (1939), SLOBODA (1971) sowie eine logistische Funktion. Nach abschließender Prüfung ergab die SLOBODA-Funktion (1971) den besten Kompromiss zwischen statistischer Anpassung und biologischer Plausibilität. Für das notwendige Einheitshöhenkurvenmodell wurde wie im Bereich der Datenergänzung der Ansatz von SLOBODA et al. (1993) verwendet, wobei als Prädiktoren die Oberhöhe h100 und der Oberdurchmesser d100 in die Berechnung eingingen. Die Berechnung des Höhenzuwachses eines Einzelbaumes erfolgte durch Differenzbildung zwischen den Einheitshöhen am Anfang und Ende eines Simulationsschrittes. Zur Gewährleistung der Modellplausibilität und um sicherzustellen, dass die Bestandesdichte nicht ungehindert ansteigt, war die Parametrisierung eines Mortalitätsmodells notwendig. Da innerhalb des Untersuchungszeitraums keine Einzelbaummortalität beobachtet werden konnte und somit die Umsetzung komplexer Modelle nicht möglich war, wurde auf die Bestandesdichte-Regel nach REINEKE (1933) zurückgegriffen. Mithilfe des Mitteldurchmessers dg und der ermittelten Grenzbeziehung können die maximale Stammzahl Nmax und somit auch die maximale Grundfläche Gmax für einen Bestand berechnet werden. Erreicht die Grundfläche eines Bestandes den berechneten Maximalwert, so sterben Bäume mit dem höchsten Konkurrenzindex ab. / The sustainable management of forest ecosystems is one of the most important requirements in forestry decisions. In this context, this thesis deals with the model-based description of individual tree growth of the tree species Pinus caribaea var. hondurensis and provides the basis for the development of sustainable management concepts in the Dominican Republic. The data for the calculation of stand yield values and for the following modeling process was based on 30 sample plots. The measurements in the pine stands were made in the years 2008, 2009 and 2010. Sixteen sample plots were placed in the region of Jarabacoa and 14 plots were located close to the city of Restauración. After the selection of specific plot size in the stand, all trees were marked and the diameter d1,3, tree height h, crown width kb, crown base ka and tree positions were measured. Using these measurements, yield parameters could be calculated. The stand age t covered a range from 3 to 38 years. The mean quadratic diameter dg varied between a minimum value of 8,1 cm and a maximum of 38,4 cm. Furthermore, mean heights hg with values of 6,7 m to 33,7 m could be determined. The stand basal area G were measured with values between 11,3 m² and 63,0 m². Based on the results of the calculation of yield parameters and the growth simulator BWINPro (NAGEL 1999), a regional growth model was adjusted. For this objective, adaptations in model routines for data generation, growth prediction and mortality were necessary. The Adaption of routines for the data generation required changes in the algorithms of tree diameter estimation and individual tree height prediction. For the generation of diameter values, the Weibull distribution was adjusted to each diameter distribution of the different stands. In a second step, linear equations which describe the scale parameter b and the shape parameter c of this distribution were fitted by using the independent variables of mean quadratic diameter dg and the maximum diameter dmax. In case where no height measurements taken, a generalized diameter-height equation is parameterized. In this context the two models from SLOBODA et al. (1993) and ARCANGELI et al. (2013) were used and compared. The equation of SLOBODA et al. (1993) showed a better suitability. In order to produce heights with a certain variation, the model after ALBERT (2000) was adjusted. With this model it is now possible, to calculate the standard deviation of the height residuals around the height curve of MICHAILOFF (1943) with the predictor dg. Crown width and crown base functions are required in the model routines for data generation and growth prediction. For the determination of a suitable crown base model, the functions of SCHMIDT (2001), of VAN DEUSEN und BIGING (1985) and from PRETZSCH (2001) were included in the study. The function of SCHMIDT (2001), which is also used in the version of BWINPro in Lower Saxony, showed the best adaption to the empirical data. For the estimation of crown width values the functions of the growth simulator Silva (PRETZSCH 2001) and BWINPro (DÖBBELER et al. 2011) were tested. Here, the function from Silva proved to be better suited. To adapt the growth prediction routines for the tree species P. caribaea var. hondurensis under the conditions in the Dominican Republic, the actualization of diameter and height growth models were necessary. The diameter growth model is based on the approach of NAGEL (1999). As independent variables the crown surface area km, stand age t and the position independent competition index C66 by WENSEL et al. (1987) were used. The calculation was performed only with trees, of which the diameter d1,3, tree height h, crown width kb and crown base ka existed as empirical measurements. Because of this limitation, the sample size consists of only 475 trees. A good result of the statistical fit was achieved with an adjusted coefficient of determination of 0,6409. The comparison to other studies supports this assertion. A direct estimation of individual tree height growth similar to the diameter increment model could not be implemented due to lack of height measurements. For this reason a method for calculating the height growth of single trees on the basis of a generalized diameter-height equation is recommended. The implementation of the described approach can be carried out in accordance to KAHN and ĎURSKÝ (1999). The requirements for using this approach are a generalized diameter-height equation and a growth function for the stand height. To ensure consistency between the two necessary models, the parameterization is based on the dominant height h100 and the dominant diameter d100. By using these values, the functions are also more stable with regard to thinning. For the adaptation of an age-height curve to describe the top height development, different growth functions were tested. These include the CHAPMAN-RICHARDS function (RICHARDS 1959), the functions of GOMPERTZ (1825), KORF (1939), SCHUMACHER (1939), SLOBODA (1971) and a logistic function. After a comprehensive evaluation, the SLOBODA function (1971) represents the best compromise between statistical adaptation and biological plausibility. For the necessary generalized diameter-height equation, again the approach of SLOBODA et al. (1993) was used, with the predictors dominant height h100 and the dominant diameter d100. The calculation of the height increment of a single tree is set by the difference between the heights from the generalized diameter-height equation at the beginning and the end of one simulation step. The age-height curve is used to extract the required information for the generalized diameter-height equation. To ensure the plausibility of the whole growth model and to ensure that the stand density does not rise unlimited, the adjustment of a mortality model was necessary. Within the research period no individual tree mortality was observed and the implementation of complex models was not possible. For this reason the stand density rule by REINEKE (1933) was implemented. By using the mean quadratic diameter dg and the estimated equation, it is possible to calculate the maximum tree number Nmax. Furthermore the maximum basal area Gmax can be calculated by multiplying Nmax with the basal area of the dg. If the basal area G of the simulated forest stand exceeds the maximum basal area Gmax, the trees with the highest competition index die. The elimination of trees stops if G is lower than Gmax. / El uso sostenible del bosque representa uno de los requisitos más importantes de la gestión forestal. En este contexto, el presente trabajo expone un modelo de crecimiento individual de la especie de árbol Pinus caribaea var. hondurensis, el mismo que pretende contribuir a sentar las bases para el desarrollo de conceptos de aprovechamiento sostenible en la República Dominicana. La base para el cálculo de valores de rendimiento y para el modelaje la constituyeron los datos tomados en 30 parcelas de muestreo en los años 2008, 2009 y 2010. La ubicación de las parcelas fue georeferenciada; 16 de ellas se encuentran en la región de Jarabacoa y 14 parcelas están en la región Restauración. Cada árbol fue marcado, se registró su ubicación dentro de la parcela y se tomaron las respectivas medidas de diámetro (d1,3), altura (h), diámetro de copa (kb) y altura de fuste limpio (ka). La edad de los árboles en las parcelas de muestreo cubrió un rango desde los tres hasta los 38 años. El diámetro a 1,3 m correspondiente al árbol de área basal promedio (dg) varió entre un mínimo de 8,1 cm hasta un máximo de 38,4cm. También se determinó que la altura de los árboles con área basal promedio (hg) fue de entre 6,7 m hasta 33,7 m. Mientras que el área basal (G) presentó valores entre 11,3 m² y 63,0 m². A partir de estos resultados de análisis básico y a través de la utilización del programa de simulación del crecimiento individual de árboles BWINPro (NAGEL 1999), se elaboró un modelo de crecimiento específico para la región. Con este propósito, fue necesario realizar modificaciones para calcular valores faltantes, los pronósticos de incremento y para replicar los valores de mortalidad. En cuanto al cálculo de los valores faltantes, se adaptaron las funciones para generar una lista de diámetros y de alturas de cada uno de los árboles. El cálculo del diámetro de cada árbol se basó en la distribución de Weibull y en ecuaciones lineales que describen el parámetro de escala b y el parámetro de forma c de dicha distribución. En este sentido, se utilizó el diámetro a 1,3 m correspondiente al árbol de área basal promedio (dg) y el diámetro máximo dmax como predictores. Con el fin de generar las alturas de cada árbol se adaptaron dos modelos generalizados de diámetro-altura y se avaluó su aptitud. El modelo de SLOBODA et al. (1993) demostró ser más apto para simular la altura de los árboles comparado con el de ARCANGELI et al. (2013). Para producir una cierta variación en la distribución de alturas generadas se ajustó adicionalmente un modelo según ALBERT (2000). El modelo con la variable independiente dg es el que resultó ser más adecuado para calcular las desviaciones estándar de los residuos de las alturas de los árboles con respecto a la ecuacion altura-diámetro de MICHAILOFF (1943). Tanto para el cálculo de los valores faltantes, como para realizar los pronósticos de incremento, se requieren funciones para determinar la altura de fuste limpio y el diámetro de copa. Con el fin de identificar un modelo adecuado para calcular la altura de fuste limpio se utilizaron las funciones de SCHMIDT (2001), VAN DEUSEN y BIGING (1985), así como también la de PRETZSCH (2001). La función de SCHMIDT (2001), que también es utilizada en la versión de BWINPro de Baja Sajonia, es la que presentó el mejor ajuste a los datos disponibles. En la búsqueda de una función adecuada para calcular el diámetro de copa, se consideraron los modelos de simulación de crecimiento de Silva (PRETZSCH 2001) y BWINPro (DÖBBELER et al. 2011). Entre ellos, el de Silva resultó ser el más adecuado. Las funciones para calcular el incremento del diámetro y la altura fueron actualizadas para ajustar el pronóstico de incremento de la especie P. caribaea var. hondurensis bajo las condiciones ambientales de la República Dominicana. El modelo para calcular el incremento del diámetro se basa principalmente en el enfoque de NAGEL (1999). Como variables independientes se consideraron el área superficial de copa (km), la edad de la plantación (t) y el índice de competencia (C66) según WENSEL et al. (1987). El cálculo consideró exclusivamente aquellos árboles cuyos valores de diámetro (d1,3), altura (h), diámetro de copa (kb) y altura de fuste limpio (ka) fueron medidos. A causa de esta limitación el tamaño de la muestra fue de únicamente 475 árboles. A pesar de esto, y en comparación con otras investigaciones se logró un buen resultado con un coeficiente de determinación ajustado de 0,6409. Una estimación directa del incremento de la altura individual análoga a la estimación del incremento del diámetro, no fue posible debido a que faltaban datos del incremento de altura. Por esta razón, el presente trabajo recomienda utilizar un procedimiento para calcular el incremento de la altura basado en una función diámetro-altura. La aplicación de tal procedimiento puede darse de conformidad al enfoque de KAHN und ĎURSKÝ (1999), que utilizaron un modelo generalizado de diámetro-altura y un modelo para describir el desarrollo de la altura del rodal. La parameterización de se basó en la altura dominante (h100) y el diámetro dominante (d100), logrando de tal manera consistencia entre ambos modelos. Además, el uso de estos valores permite que las funciones sean más estables en caso de que se realice un aclareo del bosque. Con el propósito de ajustar de una curva de altura-edad para describir el desarrollo de la altura dominante, se evaluaron varias funciones de crecimiento. Entre ellas se consideraron las de CHAPMAN-RICHARDS (RICHARDS 1959), GOMPERTZ (1825), KORF (1939), SCHUMACHER (1939), SLOBODA (1971), así como también una función logística. Tras evaluar las mencionadas funciones, la de SLOBODA (1971) fue la que presentó el mejor equilibrio entre el ajuste estadístico y la plausibilidad biológica. Para el modelo generalizado diámetro-altura se utilizó, al igual que para el cálculo de valores faltantes, el enfoque de SLOBODA et al. (1993), en el cuyos cálculos se incluyen como predictores la altura dominante (h100) y el diámetro dominante (d100). El incremento de altura de un individuo resultó de la diferencia entre la altura de cada árbol al inicio y al final de cada iteración de la simulación. Con el objeto de garantizar la plausibilidad del modelo y, para evitar que la densidad del rodal crezca libremente fue necesario parameterizar un modelo de mortalidad. Debido a que durante el tiempo de estudio no se observó la muerte de ningún árbol, y por lo cual no fue posible utilizar un modelo más complejo, se empleó la ley de densidad del rodal de Reineke, según REINEKE (1933). Con ayuda del diámetro a 1,3 m correspondiente al árbol de área basal promedio (dg) y a una relación lineal, se puede calcular el número máximo de árboles por hectárea y así también el área basal máxima de un rodal. Cuando el área basal del rodal alcanza el valor máximo calculado, mueren los árboles que poseen los índices de competencia más altos.
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"Overrun All This Country..." Two New Mexican Lives Through the Nineteenth Century

Hannigan, Isabel 14 December 2018 (has links)
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