La presente investigación tiene como finalidad determinar los principales factores que contribuyeron al incremento de las exportaciones peruanas de uva fresca a Estados Unidos durante los años 2002- 2017. Específicamente, determinar si es que la producción nacional, el precio FOB de las exportaciones peruanas a Estados Unidos y el PBI de Estados Unidos fueron factores determinantes para el incremento de las exportaciones peruanas de uva fresca a Estados Unidos durante los años 2002 - 2017. La metodología utilizada es análisis cuantitativo de tipo correlacional, ya que se pretende determinar la significancia estadística de las variables y conocer si existe o no relación entre estas. Todo esto con la finalidad de brindar información clara y real acerca de los factores que influyen en este rubro a los exportadores y todos los relacionados directa o indirectamente con este sector y sectores similares. / The purpose of the following research is to discover the main factors that determine the peruvian exports of fresh grapes between the years 2002 - 2017. Specifically, if the national production, the FOB price of the peruvian exports and the US GDP were determining factors for the increase in the peruvian export of fresh grapes between the years 2002 - 2017. The methodology used was a quantitative study with a correlational analysis, because we are trying to determine the statistical significance of the variables and to know if there is a relationship between them. All of this with the intention of giving clear and real information about the determining factors that influence this sector to the exporters and everyone that is directly or indirectly related to this sector or similar ones. / Tesis

Recent developments have confirmed that in the future hydrogen demand in industrial applications will arise because of the growing requirements for H2 in chemical manufacturing, petroleum refining, and the newly emerging clean energy concepts. Hydrogen is mainly produced from the steam reforming of natural gas and water gas shift reactions. The major products of these processes are hydrogen and carbon dioxide. The selective removal of CO2 from the product gas is important because it poisons catalysts in the reactor and it is highly corrosive. Membrane separation processes for hydrogen purification may be employed as alternative for conventional methods such as adsorption, cryogenic distillation. Mixed matrix membranes (MMMs) are composed of an insoluble phase dispersed homogeneously in a continuous polymer matrix. They have potential in gas separation applications by combining the advantageous properties of both phases. The objective of this study is to produce neat polybenzimidazole (PBI) membranes and PBI based mixed matrix membranes for separation of H2/CO2. Furthermore, to test the gas permeation performance of the prepared membranes at permeation temperatures of 35oC to 90oC. Commercial PBI supplied from both Celanese and FumaTech were used as polymer matrix. PBI was selected based on its thermal, chemical stabilities and mechanical properties and its performance as a fuel-cell membrane produced by PBI. Micro-sized Zeolite 3A and nano-sized SAPO-34 are zeolites with 0.30 nm and 0.38 nm pore size respectively have attracted considerable interest and employed as fillers in this study. Commercial Zeolite 3A and synthesized SAPO-34 by our group was used throughout the study. Membranes were prepared using N,N-dimethylacetamide as the solvent. Prepared membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The effect of annealing procedure and operating temperature on gas separation performance of resultant neat PBI, PBI/Zeolite 3A and PBI/SAPO-34 membranes were investigated by gas permeation tests. Hydrogen and carbon dioxide gases were used for single gas permeation measurements. Two different annealing strategies were utilized namely in-line annealing and in-oven annealing. In-oven annealing was performed in an oven in nitrogen atmosphere at 120oC, 0.7 atm while in-line annealing was performed in the gas permeation set-up by feeding helium as permeating gas at 90oC and 3 bar. Neat PBI and PBI/ Zeolite 3A membranes were in-oven annealed. The in-oven annealed membranes showed better selectivities with lower permeabilities, but the performance results of these membranes had low repeatability. On the other hand, in-line annealed membranes showed much higher permeabilities and lower selectivities with stable performance. By changing the annealing method hydrogen permeability increased from 5.16 Barrer to almost 7.77 barrer for neat membranes and for PBI/Zeolite 3A mixed matrix membranes increased from 5.55 to to 7.69 Barrer at 35oC. The selectivities were decreased from 6.21 to 2.31 for neat membranes and for PBI/Zeolite 3A from 5.55 to 2.63. Effect of increasing operating temperature was investigated by using in-line annealed membranes. Increasing temperature from 35oC to 90o improved the performance of the both types of membranes and repeatable results were obtained. Besides neat PBI and PBI/Zeolite 3A, PBI/SAPO-34 membranes were prepared only via in-line annealing. The addition of nano-sized filer to the membranes provided homogeneous distribution in polymer matrix for PBI/SAPO-34 membranes. For this type of membrane hydrogen permeability increased from 8.01 to 26.73 Barrer and with no change in H2/CO2 selectivities via rising temperature. Consequently, it is better to study hydrogen and carbon dioxide separation at high temperature. For all types of membranes hydrogen showed higher activation energies. In between all membranes magnitude of activation energies were the highest for PBI/SAPO-34 membrane which is an indication of good interaction between polymer and zeolite interface. In-line annealed membranes gave the best gas permeation results by providing repeatability of measurements. Among all studied membranes in-line annealed PBI/SAPO-34 membrane exhibited the best gas permeation results.

Bakgrund: Det är idag en väl etablerad sanning att bröstbevarande operation medefterföljande helbröstbestrålning är ett patientsäkert alternativ till att operera bort hela bröstet(mastektomi) vid primär bröstcancer. Det är fortfarande rutin att föreslå strålbehandling tillalla kvinnor som genomgått bröstbevarande operation även om vi vet att nyttan avstrålbehandlingen är individuell. Medan nyttan varierar är biverkningarna mera generella. Devanligaste biverkningarna drabbar hjärtat och lungorna. För att minimera biverkningarna kanman antingen bara stråla en del av bröstet (PBI) eller helt avstå strålbehandling.Syfte: Syftet med denna studie var att undersöka och se om äldre kvinnor opererade medbröstbevarande operation för lågrisk bröstcancer har nytta av strålbehandling och i så fall ivilken grad.Metod: En systematisk litteraturstudie med PubMed som vald databas för att samla relevantapublicerade artiklar. Relevanta sökord som användes var; breast cancer, breast conservingsurgery, radiotherapy, low risk, omitting och partial breast irradation Resultat: Totalt inkluderades 10 artiklar efter att ha identifierat 65 abstrakt varav 21 artiklarlästes i fulltext. Studier som jämför helbröst strålbehandling mot inget visar en statistisktsignifikant ökad risk för lokalt recidiv om man avstår strålbehandling, men i absoluta tal ärskillnaden liten och försämrar inte överlevnaden. Studier som jämför delbröst mot helbröststrålbehandling visar att delbröst strålbehandling i direkt anslutning till bröstbevarandeoperation inte ökar risken för lokalt recidiv och försämrar inte överlevnaden.Slutsats: För kvinnor >45 år är PBI i direkt anslutning till bröstbevarande operation ett säkertalternativ till helbröst strålbehandling. För äldre kvinnor (>65–70 år) med hormonkänsliglågrisk bröstcancer är det ett alternativ att helt avstå strålbehandling.

El presente trabajo analiza el efecto de la descentralización fiscal sobre las disparidades regionales en el Perú. Para realizar el análisis se usa un panel de datos de los 24 departamentos más la provincia constitucional del Callao para el periodo del 2007 al 2018. El modelo es estimado por el método generalizado de momentos (GMM) bajo el estimador de Arellano-Bond y Arellano-Bover. Los resultados empíricos muestran la existencia de una relación inversa entre las variables bajo estudio, es decir la descentralización fiscal ayuda a reducir las disparidades regionales. Este resultado está acorde con el Teorema de Descentralización y el Teorema de Tiebout. Asimismo, las variables de control PBI per cápita y gasto público son significativas bajo las especificaciones estudiadas. Sin embargo, la introducción de la variable gobernabilidad como un proxy del nivel de institucional, no resulta significativa para explicar las disparidades regionales. / This paper analyzes the effect of fiscal decentralization on the regional disparities of Peru. For this, a data panel is constructed with the 24 departments and the constitutional province of Callao during the period from 2007 to 2018. The model is estimated using the Generalized Method of Moments (GMM) with the Arellano-Bond and Arellano-Bover estimator. The empirical results confirm the inverse relationship between variables studied. In other words, fiscal decentralization reduced regional disparities. This is supported by the Decentralization Theorem and the Tiebout Theorem. Moreover, the control variables of GDP per capita and public spending are significant. However, the introduction of the governance variable as a proxy for the institutional level is not significant to explain regional disparities. / Trabajo de investigación

El documento busca analizar el posible impacto del Fondo de Estabilización de los Precios de los Combustibles derivados del petróleo (FEPC) en variables macroeconómicas de interés, como el PBI, la inflación y la Deuda Pública. El punto fundamental del análisis es debido a la inestabilidad que generan las volatilidades de los precios internacionales del petróleo en economías dependientes del recurso, como la es el Perú. Además, de identificar si las herramientas de estabilización, como lo es el fondo, son ejecutadas de manera eficiente sin generar efectos adversos que puedan perjudicar otras aspectos de la economía. En el documento se encontraron evidencias empíricas sobre la finalidad de la estabilización de precios en diversos aspectos, así como el nacimiento de la necesidad de estos dependiendo de la situación del país frente a los recursos extractivos. Se hizo uso de un modelo de vectores de autocorrección (VAR), para estimar el efecto que poseen los diversos tipos de combustibles, haciendo uso de los precios internacionales y los establecidos por el FEPC. Se usaron datos mensuales para realizar la estimación, del periodo 2008-2018 y fueron extraídos del Banco Central de Reserva del Perú y del Organismo Supervisor de la Inversión en Energía y Minería. La síntesis de la investigación indico que el FEPC cumple con su función principal de ejecutar una estabilización de los precios de los combustibles, suavizando los choques externos a la economía peruana; sin embargo, se requieren realizar modificaciones en el fondo debido a efectos colaterales que lo hacen insostenible en el tiempo. / The developed document examines the impact of the Stabilization Fund for the prices of petroleum-derived fuels (FEPC, in Spanish) in macroeconomic variables of interest, such as GDP, inflation and public debt. The main reason for this study is due for the instability generated by volatilities in international oil prices in resource dependent economies, such as Peru. In addition, to identify if the stabilization tools, such as the fund, are executed efficiently without generating adverse effects that could harm other aspects of the economy. The document found empirical evidence on the purpose of price stabilization in various aspects, as well as the birth of their need depending on the country's situation with respect to extractive resources. A model of autocorrect vectors (VAR) was used to estimate the effect of various types of fuels, using international prices and those established by the FEPC. Monthly data were used to make the estimate, for the period 2008-2018 and were extracted from the Central Reserve Bank of Peru and the Supervisory Agency for Investment in Energy and Mining. The synthesis of the investigation indicated that the FEPC fulfills its main function of executing a stabilization of fuel prices, softening external shocks to the Peruvian economy, however, modifications to the fund are required due to collateral effects that they make it unsustainable over time. / Trabajo de investigación

No description available.

The environmentally unsafe by-products (CO2, H2S, NOx and SO2 for example) of using carbon-based fuels for energy generation have paved the way for research on cleaner, renewable and possibly cheaper alternative energy production methods. Hydrogen gas, which is considered as an energy carrier, can be applied in a fuel cell setup for the production of electrical energy. Although various methods of hydrogen production are available, sulphur-based thermochemical processes (such as the Hybrid Sulfur Process (HyS)) are favoured as alternative options for large scale application. The SO2 electrolyser is applied in producing H2 gas and H2SO4 by electrochemically converting SO2 gas and water. This study focused firstly on the evaluation of the performance of the SO2 electrolyser for the production of hydrogen and sulphuric acid, using commercially available PFSA (perfluorosulfonic acid) (Nafion®) as benchmark by evaluating i) various operating parameters (such as cell temperature and membrane thickness), ii) the influence of MEA (membrane electrode assembly) manufacturing parameters (hot pressing time and pressure) and iii) the effect of H2S as a contaminant. Subsequently, the suitability of novel PBI polyaromatic blend membranes was evaluated for application in an SO2 electrolyser. The parametric study revealed that, depending on the desired operating voltage and acid concentration, the optimisation of the operating conditions was critical. An increased cell temperature promoted both cell voltage and acid concentration while the use of thin membranes resulted in a reduced voltage and acid concentration. While an increased catalyst loading resulted in increased cell efficiency, such increase would result in an increase in manufacturing costs. Using electrochemical impedance spectroscopy at the optimised operating conditions, the MEA manufacturing process was optimised with respect to hot press pressure and time, while the effect of selected operating conditions was used to evaluate the charge transfer resistance, ohmic resistance and mass transport limitations. Results showed that the optimal hot pressing conditions were 125 kg.cm-2 and 50 kg.cm-2 for 5 minutes when using 25 and 10 cm2 active areas, respectively. The charge transfer resistance and mass transport were mostly influenced by the hot pressing procedure, while the ohmic resistance varied most with temperature. Applying the SO2 electrolyser in an alternative environment to the HyS thermochemical cycle, the effect of H2S on the SO2 electrolyser anode was investigated for the possible use of SO2 electrolysis to remove SO2 from mining off-gas which could contain H2S. Polarisation curves, EIS and CO stripping were used to evaluate the transient voltage response of various H2S levels (ppm) on cell efficiency. EIS confirmed that the charge transfer resistance increased as the H2S competed with the SO2 for active catalyst sites. Mass transport limitations were observed at high H2S levels (80 ppm) while the ECSA (electrochemical surface area obtained by CO stripping) showed a significant reduction of active catalyst sites due to the presence of H2S. Pure SO2 reduced the effective active area by 89% (which is desired in this case) while the presence of 80 ppm H2S reduced the active catalyst area to 85%. The suitability of PBI-based blend membranes in the SO2 electrolyser was evaluated by using chemical stability tests and electrochemical MEA characterisation. F6PBI was used as the PBI-containing base excess polymer which was blended with either partially fluorinated aromatic polyether (sFS001), poly(2,6-dimethylbromide-1,4-phenylene oxide (PPOBr) or poly(tetrafluorostyrene-4-phosphonic acid) (PWN) in various ratios. Some of the blend membranes also contained a cross-linking agent which was specifically added in an attempt to reduce swelling and promote cross-linking within the polymer matrix. The chemical stability of the blended membranes was confirmed by using weight and swelling changes, TGA-FTIR and TGA-MS. All membranes tested showed low to no chemical degradation when exposed to 80 wt% H2SO4 at 80°C for 120 h. Once the MEA doping procedure had been optimised, electrochemical characterisation of the PBI MEAs, including polarisation curves, voltage stepping and long term operation (> 24 h) was used to evaluate the MEAs. Although performance degradation was observed for the PBI membranes during voltage stepping, it was shown that this characterisation technique could be applied with relative ease, producing valuable insights into MEA stability. Since it is expected that the SO2 electrolyser will be operated under static conditions (cell temperature, pressure and current density) in an industrial setting (HyS cycle or for SO2 removal), a long term study was included. Operating the SO2 electrolyser under constant current density of 0.1 A cm-2 confirmed that PBI-based polyaromatic membranes were suitable, if not preferred, for the SO2 environment, showing stable performance for 170 hours. This work evaluated the performance of commercial materials while further adding insights into both characterisation techniques for chemical stability of polymer materials and electrochemical methods for MEA evaluation to current published literature. In addition to the characterisation techniques this study also provides ample support for the use of PBI-based materials in the SO2 electrolyser. / PhD (Chemistry), North-West University, Potchefstroom Campus, 2015

The environmentally unsafe by-products (CO2, H2S, NOx and SO2 for example) of using carbon-based fuels for energy generation have paved the way for research on cleaner, renewable and possibly cheaper alternative energy production methods. Hydrogen gas, which is considered as an energy carrier, can be applied in a fuel cell setup for the production of electrical energy. Although various methods of hydrogen production are available, sulphur-based thermochemical processes (such as the Hybrid Sulfur Process (HyS)) are favoured as alternative options for large scale application. The SO2 electrolyser is applied in producing H2 gas and H2SO4 by electrochemically converting SO2 gas and water. This study focused firstly on the evaluation of the performance of the SO2 electrolyser for the production of hydrogen and sulphuric acid, using commercially available PFSA (perfluorosulfonic acid) (Nafion®) as benchmark by evaluating i) various operating parameters (such as cell temperature and membrane thickness), ii) the influence of MEA (membrane electrode assembly) manufacturing parameters (hot pressing time and pressure) and iii) the effect of H2S as a contaminant. Subsequently, the suitability of novel PBI polyaromatic blend membranes was evaluated for application in an SO2 electrolyser. The parametric study revealed that, depending on the desired operating voltage and acid concentration, the optimisation of the operating conditions was critical. An increased cell temperature promoted both cell voltage and acid concentration while the use of thin membranes resulted in a reduced voltage and acid concentration. While an increased catalyst loading resulted in increased cell efficiency, such increase would result in an increase in manufacturing costs. Using electrochemical impedance spectroscopy at the optimised operating conditions, the MEA manufacturing process was optimised with respect to hot press pressure and time, while the effect of selected operating conditions was used to evaluate the charge transfer resistance, ohmic resistance and mass transport limitations. Results showed that the optimal hot pressing conditions were 125 kg.cm-2 and 50 kg.cm-2 for 5 minutes when using 25 and 10 cm2 active areas, respectively. The charge transfer resistance and mass transport were mostly influenced by the hot pressing procedure, while the ohmic resistance varied most with temperature. Applying the SO2 electrolyser in an alternative environment to the HyS thermochemical cycle, the effect of H2S on the SO2 electrolyser anode was investigated for the possible use of SO2 electrolysis to remove SO2 from mining off-gas which could contain H2S. Polarisation curves, EIS and CO stripping were used to evaluate the transient voltage response of various H2S levels (ppm) on cell efficiency. EIS confirmed that the charge transfer resistance increased as the H2S competed with the SO2 for active catalyst sites. Mass transport limitations were observed at high H2S levels (80 ppm) while the ECSA (electrochemical surface area obtained by CO stripping) showed a significant reduction of active catalyst sites due to the presence of H2S. Pure SO2 reduced the effective active area by 89% (which is desired in this case) while the presence of 80 ppm H2S reduced the active catalyst area to 85%. The suitability of PBI-based blend membranes in the SO2 electrolyser was evaluated by using chemical stability tests and electrochemical MEA characterisation. F6PBI was used as the PBI-containing base excess polymer which was blended with either partially fluorinated aromatic polyether (sFS001), poly(2,6-dimethylbromide-1,4-phenylene oxide (PPOBr) or poly(tetrafluorostyrene-4-phosphonic acid) (PWN) in various ratios. Some of the blend membranes also contained a cross-linking agent which was specifically added in an attempt to reduce swelling and promote cross-linking within the polymer matrix. The chemical stability of the blended membranes was confirmed by using weight and swelling changes, TGA-FTIR and TGA-MS. All membranes tested showed low to no chemical degradation when exposed to 80 wt% H2SO4 at 80°C for 120 h. Once the MEA doping procedure had been optimised, electrochemical characterisation of the PBI MEAs, including polarisation curves, voltage stepping and long term operation (> 24 h) was used to evaluate the MEAs. Although performance degradation was observed for the PBI membranes during voltage stepping, it was shown that this characterisation technique could be applied with relative ease, producing valuable insights into MEA stability. Since it is expected that the SO2 electrolyser will be operated under static conditions (cell temperature, pressure and current density) in an industrial setting (HyS cycle or for SO2 removal), a long term study was included. Operating the SO2 electrolyser under constant current density of 0.1 A cm-2 confirmed that PBI-based polyaromatic membranes were suitable, if not preferred, for the SO2 environment, showing stable performance for 170 hours. This work evaluated the performance of commercial materials while further adding insights into both characterisation techniques for chemical stability of polymer materials and electrochemical methods for MEA evaluation to current published literature. In addition to the characterisation techniques this study also provides ample support for the use of PBI-based materials in the SO2 electrolyser. / PhD (Chemistry), North-West University, Potchefstroom Campus, 2015

Com o aumento da população mundial, o desenvolvimento de novas fontes e conversores de energia tornou-se uma necessidade. As células a combustível mostram-se como uma alternativa viável devido principalmente a duas razões, sua alta eficiência e a utilização de combustíveis renováveis. No presente trabalho se estuda a influência da temperatura de operação e o conteúdo de álcali no combustível sobre a densidade de potencia para uma célula a combustível de glicerol direto. Como combustível foi utilizado uma solução de glicerol:KOH (1M:xM, x=0, 1, 3, 5), como membranas foram utilizados filmes de polibencimidazol impregnado com ácido fosfórico (PBI/H3PO4, relação molar 1:11) ou 1-hexil-3-metilimidazol trifluorometanosulfonato (PBI/HMI-Tf relação molar 1:1.5), e finalmente, nano partículas de Pt suportadas em carbono (60% w/w) como catalizador no ânodo e no cátodo. Em geral, o incremento da temperatura e conteúdo de álcali no combustível mostra um efeito favorável na densidade de potencia do sistema. Numa célula a combustível unitária de glicerol direto utilizando membranas de PBI/ H3PO4 e PBI/HMI-Tf foram obtidas densidades de potencia de 0.54mW.cm-2 a 175°C e 0.599mW.cm-2 a 130°C, respectivamente, para uma solução de glicerol de (1M); enquanto que, para uma solução com um conteúdo maior de álcali, glicerol:KOH (1M:5M), foram obtidas densidades de potencia maiores, 44.1mW.cm-2 a 175°C e 29mW.cm-2 a 130°C, respectivamente. O efeito combinado do incremento da temperatura e concentração de álcali no combustível mostra um efeito maior em relação ao efeito só da temperatura. / With the increasing world population, the development of new energy sources or energy converters has become a necessity. Fuel cells show up as a viable alternative due mainly to two reasons, their high efficiency and the use of renewable fuels. In the present work we study the influence of operating temperature and alkali content in the fuel on the power density for a direct glycerol fuel cell. A glycerol:KOH (1M: xM, x = 0, 1, 3, 5) solution was used as fuels, as membranes were used polibencimidazol films impregnated with phosphoric acid (PBI/H3PO4, molar ratio of 1:11) or 1-hexyl-3-methylimidazolium trifluoromethanesulfonate (PBI/HMI-Tf), and finally, Pt nanoparticles supported on carbon (60% w / w) as catalyst in the anode and cathode. In general, increasing the temperature and alkali content in the fuel shows a favorable effect in the system power density. In a direct glycerol fuel cell using PBI/H3PO4 and PBI /HMI-Tf membranes were obtained power density of 0.54mW.cm-2 at 175°C and 0.599mW.cm-2 at 130°C, respectively, for a 1M glycerol solution; while for a glycerol solution with a higher content of alkali, glycerol:KOH (1M: 5M), were obtained higher power densities, 44.1mW.cm-2 at 175 ° C and 29mW.cm-2 at 130 ° C, respectively. The combined effect of increased temperature and alkali concentration in the fuel shows a greater effect compared to the effect of temperature only.

Bei der Stippelung handelt es sich um eine Oberflächenstruktur des Gingivaepithels, die der Gingiva ein orangenschalenartiges Aussehen verleiht. Ziel dieser Studie war es, die Stippelung der Gingiva von Kindern zu untersuchen und deren Merkmale sowie Prävalenz zu charakterisieren. Material und Methode: Für diese Querschnittsuntersuchung wurden insgesamt 274 Kinder untersucht (148 Jungen, 126 Mädchen; Durchschnittsalter 4,98 Jahre) und dabei der Zahnbefund, der Mundhygienezustand (API), der Entzündungszustand (PBI) und die ethnische Herkunft aufgenommen. Die Stippelung wurde photographisch und mit Abformung aus niedrig viskösem additionsvernetzenden Silikon dokumentiert. Die davon hergestellten Modelle wurden unter einem Stereomikroskop mit einer Kamera digitalisiert. Das Programm analySIS 3.0 diente zur Bildanalyse. Ergebnisse: Insgesamt zeigten 187 Kinder (68,2%) Stippelung (Jungen 67,2%, Mädchen 69%). Sie trat ab einem Alter von einem Jahr auf. Geschlecht, ethnische Herkunft, Karieserfahrung, API und PBI hatten keinen Einfluss auf die Häufigkeit. Sie kam signifikant häufiger im Wechselgebiss vor, ebenso im Oberkiefer und im Frontzahnbereich. Im Seitenvergleich konnte keine symmetrische Verteilung festgestellt werden. Die Tüpfelung kam bis auf eine Ausnahme ausschließlich auf der befestigten Gingiva vor und war dabei bevorzugt interradikulär, danach radikulär und zuletzt im subpapillären Bereich zu finden. Die Auswertung der Photographien und Replikas ergab eine durchschnittliche Dichte von 2,54 Stippel/mm2 bei einer Höhe von 0,10 mm bzw. einer Breite von 0,09 mm je Vertiefung. Ältere Kinder wiesen eine höhere Dichte der Tüpfelung auf. Alter und Geschlecht keinen Einfluss auf die morphometrischen Daten. Anzahl, Höhe und Breite der Stippelung waren im Oberkiefer und im Frontzahnbereich größer als im Unterkiefer bzw. im Seitenzahnbereich. Schlussfolgerung: Als alleiniges Kriterium zur Beurteilung des klinischen Entzündungszustandes der Gingiva bei Kindern ist die Stippelung nicht geeignet, da das Fehlen von Stippelung nicht immer mit dem Vorhandensein von gingivaler Entzündung übereinstimmt. Für eine korrekte Diagnose müssen vielmehr weitere Kriterien wie Farbe, Dicke, Festigkeit, Kontur der Gingiva, die Sondierungstiefe und Sondierungsblutung einbezogen werden. / Background: The aim of this study was to examine the gingival stippling in children and to characterize it. The prevalence of stippling was a special interest. Stippling is a structure of the gingival epithelium, which causes an orange peel like appearance of the gingiva. Material and methods: In this cross-sectional study 274 children (148 boys and 126 girls; average age 4.98 years) were examined. Oral status, approximal plaque index (API), papillary bleeding index (PBI) and race were noted. Photographs or replicas with a silicone impression material of low viscosity were taken if stippling was found. The replicas were used to make stone casts, which were scanned by a video camera. The obtained pictures were analysed with the software analysis 3.0. Results: 68.2% of the children showed stippling, in 67.2% of the boys and 69.0% of the girls. It was evident from an age of one year. Sex and race did not show any influence on prevalence. There was also no relation between stippling and caries, oral hygiene or gingival inflammation. Stippling was more frequent in mixed dentition than in deciduous dentition. The children showed more stippling in the upper jaw and in the anterior region. It was not spread symmetrically. Usually, it was localized to the attached gingiva with the highest frequency in the interradicular area, followed by the radicular area, and subpapillar area. Only one child showed stippling in the free gingiva, too, but this seemed to be an exception from the rule. The data obtained from photographs and replicas showed a density of 2,54 stipples per mm2, a height of 0.10 mm and a width of 0.09 mm. Older children showed a higher density. Height and width were neither influenced by sex nor by age. But stippling in upper arch and anterior region had a higher density and a larger height and width than in lower arch or posterior region. Conclusion: Gingival Stippling is not a major criterion in clinical assessment of gingival or periodontal inflammation, because missing stippling does not always coincide with presence of gingival inflammation. For a correct diagnosis more criteria, e.g. colour, contour, thickness, consistency, pocket depth and bleeding on probing, have to be considered, too.