Böden in der Dauerbeobachtung: Räumliche und zeitliche Veränderung von organischem Kohlenstoff und Gesamtstickstoff im Oberboden auf fünf unterschiedlich genutzten Ackerstandorten im Biosphärenreservat Schorfheide-Chorin

Die Biosphärenreservate sind durch die Vorgaben des MAB-Programms dazu angehalten eine ökosystemar ausgerichtete Umweltbeobachtung zu installieren. Im Rahmen der „Ökosystemaren Umweltbeobachtungen in den Biosphärenreservaten Brandenburgs“(ÖUB) werden seit 1999 regelmäßig fünf Ackerstandorte im Biophärenreservat Schorfheide-Chorin (BR SC) untersucht. Der Boden stellt dabei, neben der Flora und Fauna, einen wichtigen Untersuchungskomplex dar. Ziel der Beobachtung ist es Veränderungen der Bodenfunktionen (Veränderungen der Humusgehalte, Trophie) auf unterschiedlichen Standorttypen und unter differierender Bewirtschaftung (konventionell und Ökolandbau) aufzuzeigen. Aus diesem Grund sind jeweils zwei „Standortpaare“ mit ähnlicher Bodenformenausstattung (Pararendzina-Parabraunerden-Kolluvisol auf D5b2-07-Standort bzw. Parabraunerde-Kolluvisol auf D5a1-09-Standort), aber unterschiedlicher Bewirtschaftungsform ausgewählt worden. Alle diese Dauerbeobachtungsflächen weisen ein mittel bis stark welliges Relief mit eingestreuten Söllen auf. Der fünfte Standort ist ein Acker mit durchgängig sandigem Substrat (D1a1-01-Standort), der zu DDR-Zeiten als Güllehochlastfläche diente. Um die in sich sehr heterogenen Standorte hinsichtlich ihrer strukturellen und chemischen Bodenentwicklung charakterisieren zu können, wurden jeweils Hangcatenen zur Beprobung angelegt und in einem 3 bzw. 6-jährigen Turnus untersucht. Im Beitrag werden Ergebnisse der 18-jährigen Untersuchungsreihen der fünf Hangcatenen präsentiert. Der Fokus wird auf die Beschreibung und Interpretation von zeitlichen Veränderungen des organischen Kohlenstoffs und des Gesamtstickstoffs entlang der Hangcatenen gelegt einschließlich der räumlichen Differenzierungen. Die aufgezeigten Entwicklungen werden den erhobenen Daten zur Nutzung und Witterungsdaten gegenübergestellt und analysiert, welchen Einfluss die verschiedenen Bewirtschaftungsformen bzw. die Witterung auf beide Parameter ausüben. Außerdem wird analysiert, ob sich innerhalb des Untersuchungszeitraumes Unterschiede im räumlichen Muster entlang der Catena ergeben haben

Leitfaden zum Erstellen wissenschaftlicher Arbeiten im Studiengang Erziehungswissenschaft

Mit dem vorliegenden Leitfaden wird das Ziel verfolgt, Ihnen als Studierende der Erziehungswissenschaft eine Orientierungshilfe beim Erstellen wissenschaftlicher Arbeiten zu geben und Sie mit den hierbei zu beachtenden grundlegenden Regeln vertraut zu machen, die an der Universität vom Fachbereich festgelegt sind. Diese Regeln sowie ergänzende Hinweise zu häufigen Fehlern und typischen Problemen sollen Ihnen dabei helfen, Ihre akademische Ausbildung erfolgreich zu gestalten. Zudem tragen sie zur Qualitätssicherung bei

The Randomized Shortened Dental Arch Study: Tooth Loss

The evidence concerning the management of shortened dental arch (SDA) cases is sparse. This multi-center study was aimed at generating data on outcomes and survival rates for two common treatments, removable dental prostheses (RDP) for molar replacement or no replacement (SDA). The hypothesis was that the treatments lead to different incidences of tooth loss. We included 215 patients with complete molar loss in one jaw. Molars were either replaced by RDP or not replaced, according to the SDA concept. First tooth loss after treatment was the primary outcome measure. This event occurred in 13 patients in the RDP group and nine patients in the SDA group. The respective Kaplan-Meier survival rates at 38 months were 0.83 (95% CI: 0.74-0.91) in the RDP group and 0.86 (95% CI: 0.78-0.95) in the SDA group, the difference being non-significant

Availability of central α4β2* nicotinic acetylcholine receptors in human obesity

Purpose: Obesity is thought to arise, in part, from deficits in the inhibitory control over appetitive behavior. Such motivational processes are regulated by neuromodulators, specifically acetylcholine (ACh), via α4β2* nicotinic ACh receptors (nAChR). These nAChR are highly enriched in the thalamus and contribute to the thalamic gating of cortico-striatal signaling, but also act on the mesoaccumbal reward system. The changes in α4β2* nAChR availability, however, have not been demonstrated in human obesity thus far. The aim of our study was, thus, to investigate whether there is altered brain α4β2* nAChR availability in individuals with obesity compared to normal-weight healthy controls. Methods: We studied 15 non-smoking individuals with obesity (body mass index, BMI: 37.8 ± 3.1 kg/m2; age: 39 ± 14 years, 9 females) and 16 normal-weight controls (non-smokers, BMI: 21.9 ± 1.7 kg/m2; age: 28 ± 7 years, 13 females) by using PET and the α4β2* nAChR selective (−)-[18F]flubatine, which was applied within a bolus-infusion protocol (294 ± 16 MBq). Volume-of-interest (VOI) analysis was performed in order to calculate the regional total distribution volume (VT). Results: No overall significant difference in VT between the individuals with obesity and the normal-weight volunteers was found, while the VT in the nucleus basalis of Meynert tended to be lower in the individuals with obesity (10.1 ± 2.1 versus 11.9 ± 2.2; p = 0.10), and the VT in the thalamus showed a tendency towards higher values in the individuals with obesity (26.5 ± 2.5 versus 25.9 ± 4.2; p = 0.09). Conclusion: While these first data do not show greater brain α4β2* nAChR availability in human obesity overall, the findings of potentially aberrant α4β2* nAChR availability in the key brain regions that regulate feeding behavior merit further exploration

A new portable vibrator for plaster pouring: effect on the marginal fit at cylinder-abutment

OBJECTIVE: The aim of this study was to test a new portable vibrator for plaster pouring (developed for this purpose), comparing the effect of its use on the accuracy of working cast of implant-supported restorations to the conventional vibrator. MATERIAL AND METHODS: From a master cast with 2 implants, 30 transfer moldings were made randomly and divided into three groups: Group I (GI): pouring performed in an outsourced dental laboratory with conventional plaster vibrator (10 casts), Group II (GII): pouring performed in the laboratory of the Federal University of Santa Catarina (UFSC) with conventional plaster vibrator (10 casts) and Group III (GIII): pouring performed with the portable vibrator fabricated for this study (10 casts). The position of the analogue and marginal adaptation of the infrastructure were verified by testing the single screw on the master model and on the working model. The measurement of misfit was blindly performed with a precision microscope and analyzing unit, Quadra-Check 200. The data were statistically analyzed by analysis of variance (ANOVA) and the Holm-Sidak test (α=0.05). RESULTS: Means±standard deviations were as follows: GI: 19.19±4.73 µm; GII: 21.72±5.41 µm; GIII: 13.5±2.39 µm (P<0.05), with GIII significantly lower as compared to the other groups. CONCLUSION: Within the limitations of this study, it was concluded that a greater accuracy of working cast was achieved when a portable vibrator was used for casting molds

Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes

Background: The purpose of this study was to compare two impression techniques from the perspective of patient preferences and treatment comfort.Methods: Twenty-four (12 male, 12 female) subjects who had no previous experience with either conventional or digital impression participated in this study. Conventional impressions of maxillary and mandibular dental arches were taken with a polyether impression material (Impregum, 3 M ESPE), and bite registrations were made with polysiloxane bite registration material (Futar D, Kettenbach). Two weeks later, digital impressions and bite scans were performed using an intra-oral scanner (CEREC Omnicam, Sirona). Immediately after the impressions were made, the subjects' attitudes, preferences and perceptions towards impression techniques were evaluated using a standardized questionnaire. The perceived source of stress was evaluated using the State-Trait Anxiety Scale. Processing steps of the impression techniques (tray selection, working time etc.) were recorded in seconds. Statistical analyses were performed with the Wilcoxon Rank test, and p < 0.05 was considered significant.Results: There were significant differences among the groups (p < 0.05) in terms of total working time and processing steps. Patients stated that digital impressions were more comfortable than conventional techniques.Conclusions: Digital impressions resulted in a more time-efficient technique than conventional impressions. Patients preferred the digital impression technique rather than conventional techniques

Survival Rate, Fracture Strength and Failure Mode of Ceramic Implant Abutments After Chewing Simulation

The aim of this study was to compare titanium-reinforced ZrO2 and pure Al2O3 abutments regarding their outcome after chewing simulation and static loading. Forty-eight standard diameter implants with an external hexagon were divided into three groups of 16 implants each and restored with three different types of abutments (group A: ZrO2 abutments with titanium inserts; group B: densely sintered high-purity Al2O3 abutments; group C: titanium abutments). All abutments were fixated on the implants with gold-alloy screws at 32 Ncm torque, and metal crowns were adhesively cemented onto the abutments. The specimens were exposed to 1.2 million cycles in a chewing simulator. Surviving specimens were subsequently loaded until fracture in a static testing device. Fracture loads (N) and fracture modes were recorded. A Wilcoxon Rank test to compare fracture loads among the 3 groups and a Fisher exact test to detect group differences in fracture modes were used for statistical evaluation (

Trueness of CAD/CAM digitization with a desktop scanner – an in vitro study

Desktop scanners are devices for digitization of conventional impressions or gypsum casts by indirect Computer-Aided Design/Computer-Assisted Manufacturing (CAD/CAM) in dentistry. The purpose of this in vitro study was: 1, to investigate whether virtual models produced by the extraoral scanner have the same trueness as sectioned casts; and 2, to assess if digitization with an extraoral scanner influences the surface information