Frugivores, seed dispersal and tree regeneration along a human disturbance gradient in East African tropical rainforests

Samenausbreitung und Regeneration von Bäumen sind wichtig für den langfristigen Bestand von Baum- und Frugivorengemeinschaften in tropischen Regenwäldern. Zunehmende Rohdung und Degradation gefährden den Ablauf dieser mutualistischen Prozesse in diesem Ökosystem. Um den Einfluss von kleinräumiger menschlicher Störung auf die Frugivorengemeinschaft und die zentralen Ökosystemprozesse Samenausbreitung und Regeneration zu erforschen, habe ich 1) die Frugivorengemeinschaft und die Samenausbreitungsrate von Celtis durandii (Ulmaceae) und 2) den Zusammenhang zwischen Baumarten mit fleischigen Früchten, Frugivoren und der Etablierung von Keimlingen dieser Baumarten in unterschiedlich stark gestörten Flächen dreier ostafrikanischer tropischer Regenwälder untersucht. Insgesamt konnte ich 40 frugivore Vogel- und Primatenarten in den drei untersuchten Waldgebieten nachweisen. Auf gering gestörten Flächen wurden mehr Frugivore als auf stark gestörten Flächen aufgenommen. Auch die Beobachtungen an C. durandii ergaben mehr frugivore Besucher in Bäumen auf gering gestörten als auf stark gestörten Flächen. Dies führte zu einer marginal signifikant höheren Samenausbreitungsrate auf den gering gestörten Flächen. Diese Ergebnisse waren auf regionaler Ebene in allen drei untersuchten Wäldern konsistent. Dies zeigt, dass kleinräumige Störung einen umfassenderen negativen Einfluss auf Frugivore und ihre Funktion als Samenausbreiter hat als zuvor angenommen. Bei der Vegetationserfassung nahm ich 131 verschiedene Baumarten mit fleischigen Früchten in den drei Regenwäldern auf. Kleinräumige menschliche Störung erhöhte den Artenreichtum dieser Baumarten marginal signifikant, hatte jedoch keinen direkten Einfluss auf die Frugivorendichte und den Artenreichtum von Keimlingen dieser Baumarten. Der Artenreichtum von Baumarten mit fleischigen Früchten zeigte einen marginal signifikant positiven Einfluss auf die Frugivorendichte, allerdings nicht auf die Keimlinge. Allerdings führte die Dichte der Frugivoren zu signifikant erhöhtem Artenreichtum der Keimlinge. Folglich scheint kleinräumige Störung die Keimlingsetablierung indirekt durch erhöhten Baumartenreichtum und erhöhte Frugivorendichte zu beeinflussen. Die Frugivorendichte hatte einen größeren Einfluss auf die Waldregeneration als kleinräumige Störung und Baumartenreichtum. Demnach scheint kleinräumige menschliche Störung sowohl positive als auch negative Effekte auf Samenausbreitung und Regeneration zu haben. Somit sind weitere Studien notwendig, die den Einfluss von kleinräumiger menschlicher Störung auf Mutualismen tropischer Regenwälder aufklären.

Chemical exfoliation of graphene and its application in organic electronics and energy storage devices

Graphene, the thinnest two-dimensional material possible, is considered as a realistic candidate for the numerous applications in electronic, energy storage and conversion devices due to its unique properties, such as high optical transmittance, high conductivity, excellent chemical and thermal stability. However, the electronic and chemical properties of graphene are highly dependent on their preparation methods. Therefore, the development of novel chemical exfoliation process which aims at high yield synthesis of high quality graphene while maintaining good solution processability is of great concern. This thesis focuses on the solution production of high-quality graphene by wet-chemical exfoliation methods and addresses the applications of the chemically exfoliated graphene in organic electronics and energy storage devices.rnPlatinum is the most commonly used catalysts for fuel cells but they suffered from sluggish electron transfer kinetics. On the other hand, heteroatom doped graphene is known to enhance not only electrical conductivity but also long term operation stability. In this regard, a simple synthetic method is developed for the nitrogen doped graphene (NG) preparation. Moreover, iron (Fe) can be incorporated into the synthetic process. As-prepared NG with and without Fe shows excellent catalytic activity and stability compared to that of Pt based catalysts.rnHigh electrical conductivity is one of the most important requirements for the application of graphene in electronic devices. Therefore, for the fabrication of electrically conductive graphene films, a novel methane plasma assisted reduction of GO is developed. The high electrical conductivity of plasma reduced GO films revealed an excellent electrochemical performance in terms of high power and energy densities when used as an electrode in the micro-supercapacitors.rnAlthough, GO can be prepared in bulk scale, large amount of defect density and low electrical conductivity are major drawbacks. To overcome the intrinsic limitation of poor quality of GO and/or reduced GO, a novel protocol is extablished for mass production of high-quality graphene by means of electrochemical exfoliation of graphite. The prepared graphene shows high electrical conductivity, low defect density and good solution processability. Furthermore, when used as electrodes in organic field-effect transistors and/or in supercapacitors, the electrochemically exfoliated graphene shows excellent device performances. The low cost and environment friendly production of such high-quality graphene is of great importance for future generation electronics and energy storage devices. rn

Cardiac transplantation with hearts from donors after circulatory declaration of death: haemodynamic and biochemical parameters at procurement predict recovery following cardioplegic storage in a rat model

OBJECTIVES: Donation after circulatory declaration of death (DCDD) could significantly improve the number of cardiac grafts for transplantation. Graft evaluation is particularly important in the setting of DCDD given that conditions of cardio-circulatory arrest and warm ischaemia differ, leading to variable tissue injury. The aim of this study was to identify, at the time of heart procurement, means to predict contractile recovery following cardioplegic storage and reperfusion using an isolated rat heart model. Identification of reliable approaches to evaluate cardiac grafts is key in the development of protocols for heart transplantation with DCDD. METHODS: Hearts isolated from anaesthetized male Wistar rats (n = 34) were exposed to various perfusion protocols. To simulate DCDD conditions, rats were exsanguinated and maintained at 37°C for 15-25 min (warm ischaemia). Isolated hearts were perfused with modified Krebs-Henseleit buffer for 10 min (unloaded), arrested with cardioplegia, stored for 3 h at 4°C and then reperfused for 120 min (unloaded for 60 min, then loaded for 60 min). Left ventricular (LV) function was assessed using an intraventricular micro-tip pressure catheter. Statistical significance was determined using the non-parametric Spearman rho correlation analysis. RESULTS: After 120 min of reperfusion, recovery of LV work measured as developed pressure (DP)-heart rate (HR) product ranged from 0 to 15 ± 6.1 mmHg beats min(-1) 10(-3) following warm ischaemia of 15-25 min. Several haemodynamic parameters measured during early, unloaded perfusion at the time of heart procurement, including HR and the peak systolic pressure-HR product, correlated significantly with contractile recovery after cardioplegic storage and 120 min of reperfusion (P < 0.001). Coronary flow, oxygen consumption and lactate dehydrogenase release also correlated significantly with contractile recovery following cardioplegic storage and 120 min of reperfusion (P < 0.05). CONCLUSIONS: Haemodynamic and biochemical parameters measured at the time of organ procurement could serve as predictive indicators of contractile recovery. We believe that evaluation of graft suitability is feasible prior to transplantation with DCDD, and may, consequently, increase donor heart availability.

Comparing remote sensing and ground-based methods of quantifying cover type and carbon storage in an urban forest

Understanding the canopy cover of an urban environment leads to better estimates of carbon storage and more informed management decisions by urban foresters. The most commonly used method for assessing urban forest cover type extent is ground surveys, which can be both timeconsuming and expensive. The analysis of aerial photos is an alternative method that is faster, cheaper, and can cover a larger number of sites, but may be less accurate. The objectives of this paper were (1) to compare three methods of cover type assessment for Los Angeles, CA: handdelineation of aerial photos in ArcMap, supervised classification of aerial photos in ERDAS Imagine, and ground-collected data using the Urban Forest Effects (UFORE) model protocol; (2) to determine how well remote sensing methods estimate carbon storage as predicted by the UFORE model; and (3) to explore the influence of tree diameter and tree density on carbon storage estimates. Four major cover types (bare ground, fine vegetation, coarse vegetation, and impervious surfaces) were determined from 348 plots (0.039 ha each) randomly stratified according to land-use. Hand-delineation was better than supervised classification at predicting ground-based measurements of cover type and UFORE model-predicted carbon storage. Most error in supervised classification resulted from shadow, which was interpreted as unknown cover type. Neither tree diameter or tree density per plot significantly affected the relationship between carbon storage and canopy cover. The efficiency of remote sensing rather than in situ data collection allows urban forest managers the ability to quickly assess a city and plan accordingly while also preserving their often-limited budget.

Surface Roughness and Microhardness of Two Recent CAD/CAM-Materials After Storage

Objectives: To investigate surface roughness and microhardness of two recent resin-ceramic materials for computer-aided design/computer-aided manufacturing (CAD/CAM) after polishing with three polishing systems. Surface roughness and microhardness were measured immediately after polishing and after six months storage including monthly artificial toothbrushing. Methods: Sixty specimens of Lava Ultimate (3M ESPE) and 60 specimens of VITA ENAMIC (VITA Zahnfabrik) were roughened in a standardized manner and polished with one of three polishing systems (n=20/group): Sof-Lex XT discs (SOFLEX; three-step (medium-superfine); 3M ESPE), VITA Polishing Set Clinical (VITA; two-step; VITA Zahnfabrik), or KENDA Unicus (KENDA; one-step; KENDA Dental). Surface roughness (Ra; μm) was measured with a profilometer and microhardness (Vickers; VHN) with a surface hardness indentation device. Ra and VHN were measured immediately after polishing and after six months storage (tap water, 37°C) including monthly artificial toothbrushing (500 cycles/month, toothpaste RDA ~70). Ra- and VHN-values were analysed with nonparametric ANOVA followed by Wilcoxon rank sum tests (α=0.05). Results: For Lava Ultimate, Ra (mean [standard deviation] before/after storage) remained the same when polished with SOFLEX (0.18 [0.09]/0.19 [0.10]; p=0.18), increased significantly with VITA (1.10 [0.44]/1.27 [0.39]; p=0.0001), and decreased significantly with KENDA (0.35 [0.07]/0.33 [0.08]; p=0.03). VHN (mean [standard deviation] before/after storage) decreased significantly regardless of polishing system (SOFLEX: 134.1 [5.6]/116.4 [3.6], VITA: 138.2 [10.5]/115.4 [5.9], KENDA: 135.1 [6.2]/116.7 [6.3]; all p<0.0001). For VITA ENAMIC, Ra (mean [standard deviation] before/after storage) increased significantly when polished with SOFLEX (0.37 [0.18]/0.41 [0.14]; p=0.01) and remained the same with VITA (1.32 [0.37]/1.31 [0.40]; p=0.58) and with KENDA (0.81 [0.35]/0.78 [0.32]; p=0.21). VHN (mean [standard deviation] before/after storage) remained the same regardless of polishing system (SOFLEX: 284.9 [24.6]/282.4 [31.8], VITA: 284.6 [28.5]/276.4 [25.8], KENDA: 292.6 [26.9]/282.9 [24.3]; p=0.42-1.00). Conclusion: Surface roughness and microhardness of Lava Ultimate was more affected by storage and artificial toothbrushing than was VITA ENAMIC.

Long-term storage affects adhesion between titanium and zirconia using resin cements.

PURPOSE To determine the impact of long-term storage on adhesion between titanium and zirconia using resin cements. MATERIALS AND METHODS Titanium grade 4 blocks were adhesively fixed onto zirconia disks with four resin cements: Panavia F 2.0 (Kuraray Europe), GC G-Cem (GC Europe), RelyX Unicem (3M ESPE), and SmartCem 2 (Dentsply DeguDent). Shear bond strength was determined after storage in a water bath for 24 h, 16, 90, and 150 days at 37°C, and after 6000 cycles between 5°C and 55°C. Fracture behavior was evaluated using scanning electron microscopy. RESULTS After storage for at least 90 days and after thermocycling, GC G-Cem (16.9 MPa and 15.1 MPa, respectively) and RelyX Unicem (10.8 MPa and 15.7 MPa, respectively) achieved higher shear bond strength compared to SmartCem 2 (7.1 MPa and 4.0 MPa, respectively) and Panavia F2 (4.1 MPa and 7.4 MPa, respectively). At day 150, GC G-Cem and RelyX Unicem caused exclusively mixed fractures. SmartCem 2 and Panavia F2 showed adhesive fractures in one-third of the cases; all other fractures were of mixed type. After 24 h (GC G-Cem: 26.0, RelyX Unicem: 20.5 MPa, SmartCem 2: 16.1 MPa, Panavia F2: 23.6 MPa) and 16 days (GC G-Cem: 12.8, RelyX Unicem: 14.2 MPa, SmartCem 2: 9.8 MPa, Panavia F2: 14.7 MPa) of storage, shear bond strength was similar among the four cements. CONCLUSION Long-term storage and thermocycling differentially affects the bonding of resin cement between titanium and zirconia.

Wound models for periodontal and bone regeneration: the role of biologic research

The ultimate goals of periodontal therapy remain the complete regeneration of those periodontal tissues lost to the destructive inflammatory-immune response, or to trauma, with tissues that possess the same structure and function, and the re-establishment of a sustainable health-promoting biofilm from one characterized by dysbiosis. This volume of Periodontology 2000 discusses the multiple facets of a transition from therapeutic empiricism during the late 1960s, toward regenerative therapies, which is founded on a clearer understanding of the biophysiology of normal structure and function. This introductory article provides an overview on the requirements of appropriate in vitro laboratory models (e.g. cell culture), of preclinical (i.e. animal) models and of human studies for periodontal wound and bone repair. Laboratory studies may provide valuable fundamental insights into basic mechanisms involved in wound repair and regeneration but also suffer from a unidimensional and simplistic approach that does not account for the complexities of the in vivo situation, in which multiple cell types and interactions all contribute to definitive outcomes. Therefore, such laboratory studies require validatory research, employing preclinical models specifically designed to demonstrate proof-of-concept efficacy, preliminary safety and adaptation to human disease scenarios. Small animal models provide the most economic and logistically feasible preliminary approaches but the outcomes do not necessarily translate to larger animal or human models. The advantages and limitations of all periodontal-regeneration models need to be carefully considered when planning investigations to ensure that the optimal design is adopted to answer the specific research question posed. Future challenges lie in the areas of stem cell research, scaffold designs, cell delivery and choice of growth factors, along with research to ensure appropriate gingival coverage in order to prevent gingival recession during the healing phase.

Sedimentation rate calculations and isotopic analysis on sediment cores along the IODP Expedition 311 transect

The oceanographic and tectonic conditions of accretionary margins are well-suited for several potential processes governing methane generation, storage and release. To identify the relevant methane evolution pathways in the northern Cascadia accretionary margin, a four-site transect was drilled during Integrated Ocean Drilling Program Expedition 311. The d13C values of methane range from a minimum value of -82.2 per mil on an uplifted ridge of accreted sediment near the deformation front (Site U1326, 1829 mbsl, meters below sea level) to a maximum value of -39.5 per mil at the most landward location within an area of steep canyons near the shelf edge (Site U1329, 946 mbsl). An interpretation based solely on methane isotope values might conclude the 13C-enrichment of methane indicates a transition from microbially- to thermogenically-sourced methane. However, the co-existing CO2 exhibits a similar trend of 13C-enrichment along the transect with values ranging from -22.5 per mil to +25.7 per mil. The magnitude of the carbon isotope separation between methane and CO2 (Ec = 63.8 ± 5.8) is consistent with isotope fractionation during microbially mediated carbonate reduction. These results, in conjunction with a transect-wide gaseous hydrocarbon content composed of > 99.8% (by volume) methane and uniform dDCH4 values (-172 per mil ± 8) that are distinct from thermogenic methane at a seep located 60 km from the Expedition 311 transect, suggest microbial CO2 reduction is the predominant methane source at all investigated sites. The magnitude of the intra-site downhole 13C-enrichment of CO2 within the accreted ridge (Site U1326) and a slope basin nearest the deformation front (Site U1325, 2195 mbsl) is ~ 5 per mil. At the mid-slope site (Site U1327, 1304 mbsl) the downhole 13C-enrichment of the CO2 is ~ 25 per mil and increases to ~ 40 per mil at the near-shelf edge Site U1329. This isotope fractionation pattern is indicative of more extensive diagenetic alteration at sites with greater 13C-enrichment. The magnitude of the 13C-enrichment of CO2 correlates with decreasing sedimentation rates and a diminishing occurrence of stratigraphic gas hydrate. We suggest the decreasing sedimentation rates increase the exposure time of sedimentary organic matter to aerobic and anaerobic degradation, during burial, thereby reducing the availability of metabolizable organic matter available for methane production. This process is reflected in the occurrence and distribution of gas hydrate within the northern Cascadia margin accretionary prism. Our observations are relevant for evaluating methane production and the occurrence of stratigraphic gas hydrate within other convergent margins.

Wetland maps including open water extent dynamics based on ENVISAT ASAR WS for Siberia, 2007 and 2008, links to GeoTIFFs

Wetlands store large amounts of carbon, and depending on their status and type, they release specific amounts of methane gas to the atmosphere. The connection between wetland type and methane emission has been investigated in various studies and utilized in climate change monitoring and modelling. For improved estimation of methane emissions, land surface models require information such as the wetland fraction and its dynamics over large areas. Existing datasets of wetland dynamics present the total amount of wetland (fraction) for each model grid cell, but do not discriminate the different wetland types like permanent lakes, periodically inundated areas or peatlands. Wetland types differently influence methane fluxes and thus their contribution to the total wetland fraction should be quantified. Especially wetlands of permafrost regions are expected to have a strong impact on future climate due to soil thawing. In this study ENIVSAT ASAR Wide Swath data was tested for operational monitoring of the distribution of areas with a long-term SW near 1 (hSW) in northern Russia (SW = degree of saturation with water, 1 = saturated), which is a specific characteristic of peatlands. For the whole northern Russia, areas with hSW were delineated and discriminated from dynamic and open water bodies for the years 2007 and 2008. The area identified with this method amounts to approximately 300,000 km**2 in northern Siberia in 2007. It overlaps with zones of high carbon storage. Comparison with a range of related datasets (static and dynamic) showed that hSW represents not only peatlands but also temporary wetlands associated with post-forest fire conditions in permafrost regions. Annual long-term monitoring of change in boreal and tundra environments is possible with the presented approach. Sentinel-1, the successor of ENVISAT ASAR, will provide data that may allow continuous monitoring of these wetland dynamics in the future complementing global observations of wetland fraction.

Abundance and sizes of European oak species (Quercus petraea (Matt.) Liebl., Quercus robur L.) in dependence of neighborhood and environmental factors

Quercus robur L. (pedunculate oak) and Quercus petraea (Matt.) Liebl. (sessile oak) are two European oak species of great economic and ecological importance. Even though both oaks have wide ecological amplitudes of suitable growing conditions, forests dominated by oaks often fail to regenerate naturally. The regeneration performance of both oak species is assumed to be subject to a variety of variables that interact with one another in complex ways. The novel approach of this research was to study the effect of many ecological variables on the regeneration performance of both oak species together and identify key variables and interactions for different development stages of the oak regeneration on a large scale in the field. For this purpose, overstory and regeneration inventories were conducted in oak dominated forests throughout southern Germany and paired with data on browsing, soil, and light availability. The study was able to verify the assumption that the occurrence of oak regeneration depends on a set of variables and their interactions. Specifically, combinations of site and stand specific variables such as light availability, soil pH and iron content on the one hand, and basal area and species composition of the overstory on the other hand. Also browsing pressure was related to oak abundance. The results also show that the importance of variables and their combinations differs among the development stages of the regeneration. Light availability becomes more important during later development stages, whereas the number of oaks in the overstory is important during early development stages. We conclude that successful natural oak regeneration is more likely to be achieved on sites with lower fertility and requires constantly controlling overstory density. Initially sufficient mature oaks in the overstory should be ensured. In later stages, overstory density should be reduced continuously to meet the increasing light demand of oak seedlings and saplings.

Hydrological and meteorological records from the Vernagtferner Basin - Vernagtbach station, for the years 1970 to 2001

The Vernagtferner region has a long tradition of glaciological research performed by groups from Munich. It started in 1889, when Prof. Sebastian Finsterwalder from the Technical University in Munich produced the first map of a complete glacier based on terrestrial photogrammetry. Since then, numerous maps of the glacier have been made, describing the change in surface elevation for more than a century. These maps form the basis of the geodetic method of glacier mass balance determination, which provides volume changes as average data for the period between two surveys, i.e. typically for 10 years. Since the start of the glaciological method on Vernagtferner in 1964, annual as well as winter and summer mass balance data are available continuously. But only since 1973, the construction of the Vernagtbach station, approximately 1 km below the glacier margin at that time, provided the means to record a larger number of hydrological and meteorological parameters with a temporal resolution of typically 1 hour.

Activity of ETS enzymes and phosphatase in the Sea of Okhotsk and Kuril region in summer 1992 and 1993

An estimate of rate of transformation of organic matter and regeneration of nutrients (in particular phosphorus) was calculated for different regions of the Sea of Okhotsk. The rate was estimated by means of rate of complete oxidation of organic matter to CO2 and H2O catalyzed by enzymes of the electron transport system (ETS) and rate of hydrolytic splitting of phosphate from organic phosphorus compounds catalyzed by alkaline phosphatase. Organic matter destruction rate was at its maximum on the shelf of Kamchatka and Sakhalin, as well as in the layer of maximum oxygen gradients in deep waters. It was found that zones of intensive primary production were characterized by high rates of phosphorus regeneration, which provided for 80% of primary production when concentration of mineral phosphorus was low.

The influence of ocean acidification on nitrogen regeneration and nitrous oxide production in the northwest European shelf sea

The assimilation and regeneration of dissolved inorganic nitrogen, and the concentration of N2O, was investigated at stations located in the NW European shelf sea during June/July 2011. These observational measurements within the photic zone demonstrated the simultaneous regeneration and assimilation of NH4+, NO2- and NO3-. NH4+ was assimilated at 1.82-49.12 nmol N/L/h and regenerated at 3.46-14.60 nmol N/L/h; NO2- was assimilated at 0-2.08 nmol N/L/h and regenerated at 0.01-1.85 nmol N/L/h; NO3-was assimilated at 0.67-18.75 nmol N/L/h and regenerated at 0.05-28.97 nmol N/L/h. Observations implied that these processes were closely coupled at the regional scale and that nitrogen recycling played an important role in sustaining phytoplankton growth during the summer. The [N2O], measured in water column profiles, was 10.13 ± 1.11 nmol/L and did not strongly diverge from atmospheric equilibrium indicating that sampled marine regions were neither a strong source nor sink of N2O to the atmosphere. Multivariate analysis of data describing water column biogeochemistry and its links to N-cycling activity failed to explain the observed variance in rates of N-regeneration and N-assimilation, possibly due to the limited number of process rate observations. In the surface waters of five further stations, ocean acidification (OA) bioassay experiments were conducted to investigate the response of NH4+ oxidising and regenerating organisms to simulated OA conditions, including the implications for [N2O]. Multivariate analysis was undertaken which considered the complete bioassay data set of measured variables describing changes in N-regeneration rate, [N2O] and the biogeochemical composition of seawater. While anticipating biogeochemical differences between locations, we aimed to test the hypothesis that the underlying mechanism through which pelagic N-regeneration responded to simulated OA conditions was independent of location. Our objective was to develop a mechanistic understanding of how NH4+ regeneration, NH4+ oxidation and N2O production responded to OA. Results indicated that N-regeneration process responses to OA treatments were location specific; no mechanistic understanding of how N-regeneration processes respond to OA in the surface ocean of the NW European shelf sea could be developed.