In situ determination of the remote sensing reflectance: an inter-comparison

Inter-comparison of data products from simultaneous measurements performed with independent systems and methods is a viable approach to assess the consistency of data and additionally to investigate uncertainties. Within such a context the inter-comparison called Assessment of In Situ Radiometric Capabilities for Coastal Water Remote Sensing Applications (ARC) was carried out at the Acqua Alta Oceanographic Tower in the northern Adriatic Sea to explore the accuracy of in situ data products from various in- and above-water optical systems and methods. Measurements were performed under almost ideal conditions, including a stable deployment platform, clear sky, relatively low sun zenith angles and moderately low sea state. Additionally, all optical sensors involved in the experiment were inter-calibrated through absolute radiometric calibration performed with the same standards and methods. Inter-compared data products include spectral water-leaving radiance Lw (λ), above-water downward irradiance Ed(0+,λ) and remote sensing reflectance Rrs(λ). Data products from the various measurement systems/methods were directly compared to those from a single reference system/method. Results for Rrs(λ) indicate spectrally averaged values of relative differences comprised between -1 and +6%, while spectrally averaged values of absolute differences vary from approximately 6% for the above-water systems/methods to 9% for buoy-based systems/methods. The agreement between Rrs(λ) spectral relative differences and estimates of combined uncertainties of the inter-compared systems/methods is noteworthy

Kreatiewe strategieë gerig op produkposisionering deur die gebruik van reklame

Reklame-agentskappe in Suid-Afrika se hantering van posisioneringsdoelwitte en -beginsels asook oorredingsbeginsels by die formulering van 'n kreatiewe reklame­ strategie is in 'n sensus deur 'n posvraelys ondersoek. Produkposisionering behels die verbruikerspersepsie van 'n handelsmerk teenoor mededinging. Persepsie be·invloed die verbruiker se houding teenoor die handelsmerk asook aankoopbesluite. Reklame kan gebruik word om doelgerig 'n gunstige persepsie van die produk te skep. Die studie toon dat respondente die belangrikheid van produkposisionering en beeldoordrag deur reklame beset asook dat handelsmerklojaliteit normaalweg beteken dat produkposisionering suksesvol was. 'n Positiewe houding teenoor die produk berus op 'n positiewe produkbeeld, terwyl produkposisionering slegs suksesvol kan wees indien dit aan belangrike persoonlike motiewe van die verbruiker gekoppel kan word. Die handelsmerkbeeld is moeilik veranderbaar, maar word deur produkkennis bevorder. Die kreatiewe strategie behels besluite oar die oorredingsdoelwitte en boodskap­ konstruksie. Respondente gebruik byna altyd posisioneringsdoelwitte (oorredings­ doelwitte) by reklameveldtogte maar nie noodwendig as formele reklamedoelwitte nie. Die unieke verkoopsaanbod (USP) en die mededingende posisie word as belangrike kreatiewe riglyne beskou. Bevindinge toon dat boodskapkonstruksie by die doel­ gehoor aanklank moet vind deur dit aan die ontvanger se persoonlike ervaring of aan getuienisse te koppel wat, teen die agtergrond van 'n onkonvensionele maar geloofwaardige benadering, deurgaans die handelsnaam en uitmuntende kreatiwiteit beklemtoon. Emosionele sowel as feitelike inligting is, volgens reklame-agentskappe, vir die oorre­ ding van die verbruiker belangrik. Rasionele argumente moet egter deur bewyse en feitelike inligting ondersteun en met "warmte" gekombineer word. Humor en vrees word as minder belangrik vir oorreding beskou. Tekortkomings is bespeur in die evaluering van die kommunikasiesukses van reklame­ veldtogte, die monitor van veranderinge in handelsmerkpersepsies en be·invloeding van verbruikerspersepsies van die mededingers se handelsmerke. Dit word vererger deur leemtes in inligting oor die ideale handelsmerk (handelsmerkvoorkeur). Respondente onderskat dikwels verbruikers se leervermoe en persepsie van die aan­ kooprisiko. Dit belemmer die begrip van die koppeling tussen die handelsmerk­ persepsie, houding en aankoopvoornemens. Reklame-agentskappe behoort kliente meer te adviseer oor die sinergie van al die bemarkingsinstrumente by produkposisionering in plaas daarvan om uitsluitlik op die meer visuele elemente te fokus.The handling, by South African advertising agencies, of positioning as well as persua­ sion objectives and principles in formulating creative advertising strategies was investi­ gated in a census by means of a postal survey. Product positioning entails the consumer's perception of a brand relative to competition. Perception influences the consumer's attitude towards brands and purchasing deci­ sions. Advertising can be used to create a favourable perception of the product. The study shows that the respondents understand the importance of product posi­ tioning and the transfer of image, and that brand loyalty normally reflects successful product positioning. A positive attitude towards the brand depends on a positive brand image, while product positioning can only be successful if linked to important personal consumer motives. Brand image is difficult to change, but is enhanced by product knowledge. The creative strategy comprises decisions about the persuasion objectives and message construction. Respondents nearly always use positioning objectives (persuasion objectives) in advertising campaigns but not necessarily as formal advertising objectives. The unique selling proposition (USP) and the competitive position are regarded as important creative guidelines. Findings show that message construction must be appealing to the target audience by involving the recipient's personal experience or testimonies, emphasising the brand name and displaying creative excellence against the background of an unconventional but credible approach. Emotional as well as factual information are, according to advertising agencies, important for persuading the consumer. Rational arguments must, however, be sub­ stantiated by factual information combined with "warmth". Humour and fear are regarded as minor contributors in persuasion. Shortcomings were detected in evaluating communication results of advertising cam­ paigns, monitoring of changes in brand perception and influencing the consumer's perception of competitors' brands. This is aggravated by a lack of information about the ideal brand (brand preference). Respondents frequently underestimate the consumer's learning ability and perception of purchase risks. This hampers the understanding of the link between brand percep­ tion, attitude and purchase intentions. Advertising agencies should offer more advice to clients regarding the synergy of all the marketing instruments in product positioning, instead of focusing exclusively on the more visual elements.Business ManagementDCom (Sakebesturr

Endonuclease EEPD1 Is a Gatekeeper for Repair of Stressed Replication Forks

Replication is not as continuous as once thought, with DNA damage frequently stalling replication forks. Aberrant repair of stressed replication forks can result in cell death or genome instability and resulting transformation to malignancy. Stressed replication forks are most commonly repaired via homologous recombination (HR), which begins with 5' end resection, mediated by exonuclease complexes, one of which contains Exo1. However, Exo1 requires free 5'-DNA ends upon which to act, and these are not commonly present in non-reversed stalled replication forks. To generate a free 5' end, stalled replication forks must therefore be cleaved. Although several candidate endonucleases have been implicated in cleavage of stalled replication forks to permit end resection, the identity of such an endonuclease remains elusive. Here we show that the 5'-endonuclease EEPD1 cleaves replication forks at the junction between the lagging parental strand and the unreplicated DNA parental double strands. This cleavage creates the structure that Exo1 requires for 5' end resection and HR initiation. We observed that EEPD1 and Exo1 interact constitutively, and Exo1 repairs stalled replication forks poorly without EEPD1. Thus, EEPD1 performs a gatekeeper function for replication fork repair by mediating the fork cleavage that permits initiation of HR-mediated repair and restart of stressed forks

Atmospheric stilling offsets the benefits from reduced nutrient loading in a large shallow lake

As part of a global phenomenon, a 30% decrease in average wind speed since 1996 in southern Estonia together with more frequent easterly winds resulted in 47% decrease in bottom shear stress in the large (270 km2), shallow (mean depth 2.8 m), and eutrophic Lake Võrtsjärv. Following a peak in eutrophication pressure in the 1970s–80s, the concentrations of total nutrients were declining. Nonmetric Multidimensional Scaling (NMDS) ordination of a 54-year phytoplankton community composition time-series (1964–2017) revealed three distinct periods with breaking points coinciding with changes in wind and/or water level. Contrary to expectations, we detected no decrease in optically active substances that could be related to wind stilling, whereas phytoplankton biomass showed an increasing trend despite reduced nutrient levels. Here we show how opening of the “light niche,” caused by declining amount of suspended sediments, was capitalized and filled by the light-limited phytoplankton community. We suggest that wind stilling is another global factor, complementary to climate warming that counteracts eutrophication mitigation in lakes and may provide a challenge to assessment of the lake ecological status.Main financial support for EMU: European Union’s Horizon 2020 research and innovation programme Under the Marie Skłodowska-Curie Action, Innovative Training Networks, European Joint Doctorates.Project name, acronym and grant number: Management of climatic extreme events in lakes and reservoirs for the protection of ecosystem services, MANTEL, grant agreement No 722518.Publication date and, if applicable, length of embargo period: Published as Early View on 07.10.2019, no embargo period.Main financial support for EMU: European Union’s Horizon 2020 research and innovation programme Under the Marie Skłodowska-Curie Action, Innovative Training Networks, European Joint Doctorate

Hyperspectral remote sensing of cyanobacterial pigments as indicators for cell populations and toxins in eutrophic lakes

The growth of mass populations of toxin-producing cyanobacteria is a serious concern for the ecological status of inland waterbodies and for human and animal health. In this study we examined the performance of four semi-analytical algorithms for the retrieval of chlorophyll a (Chl a) and phycocyanin (C-PC) from data acquired by the Compact Airborne Spectrographic Imager-2 (CASI-2) and the Airborne Imaging Spectrometer for Applications (AISA) Eagle sensor. The retrieval accuracies of the semi-analytical models were compared to those returned by optimally calibrated empirical band-ratio algorithms. The best-performing algorithm for the retrieval of Chl a was an empirical band-ratio model based on a quadratic function of the ratio of re!ectance at 710 and 670 nm (R2=0.832; RMSE=29.8%). However, this model only provided a marginally better retrieval than the best semi-analytical algorithm. The best-performing model for the retrieval of C-PC was a semi-analytical nested band-ratio model (R2=0.984; RMSE=3.98 mg m−3). The concentrations of C-PC retrieved using the semi-analytical model were correlated with cyanobacterial cell numbers (R2=0.380) and the particulate and total (particulate plus dissolved) pools of microcystins (R2=0.858 and 0.896 respectively). Importantly, both the empirical and semi-analytical algorithms were able to retrieve the concentration of C-PC at cyanobacterial cell concentrations below current warning thresholds for cyanobacteria in waterbodies. This demonstrates the potential of remote sensing to contribute to early-warning detection and monitoring of cyanobacterial blooms for human health protection at regional and global scales

An operational analysis of Lake Surface Water Temperature

Operational analyses of Lake Surface Water Temperature (LSWT) have many potential uses including improvement of numerical weather prediction (NWP) models on regional scales. In November 2011, LSWT was included in the Met Office Operational Sea Surface Temperature and Ice Analysis (OSTIA) product, for 248 lakes globally. The OSTIA analysis procedure, which has been optimised for oceans, has also been used for the lakes in this first version of the product. Infra-red satellite observations of lakes and in situ measurements are assimilated. The satellite observations are based on retrievals optimised for Sea Surface Temperature (SST) which, although they may introduce inaccuracies into the LSWT data, are currently the only near-real-time information available. The LSWT analysis has a global root mean square difference of 1.31 K and a mean difference of 0.65 K (including a cool skin effect of 0.2 K) compared to independent data from the ESA ARC-Lake project for a 3-month period (June to August 2009). It is demonstrated that the OSTIA LSWT is an improvement over the use of climatology to capture the day-to-day variation in global lake surface temperatures

Spectra of a shallow sea-unmixing for class identification and monitoring of coastal waters

Ocean colour-based monitoring of water masses is a promising alternative to monitoring concentrations in heterogeneous coastal seas. Fuzzy methods, such as spectral unmixing, are especially well suited for recognition of water masses from their remote sensing reflectances. However, such models have not yet been applied for water classification and monitoring. In this study, a fully constrained endmember model with simulated endmembers was developed for water class identification in the shallow Wadden Sea and adjacent German Bight. Its performance was examined on in situ measured reflectances and on MERIS satellite data. Water classification by means of unmixing reflectance spectra proved to be successful. When the endmember model was applied to MERIS data, it was able to visualise well-known spatial, tidal, seasonal, and wind-related variations in optical properties in the heterogeneous Wadden Sea. Analyses show that the method is insensitive to small changes in endmembers. Therefore, it can be applied in similar coastal areas. For use in open ocean situations or coastal or inland waters with other specific inherent optical properties, re-simulation of the endmember spectra with local optical properties is required. However, such an adaptation requires only a limited number of local in situ measurements