Temperature and residence time controls on an estuarine harmful algal bloom: Modeling hydrodynamics and Alexandrium fundyense in Nauset estuary.

A highly resolved, 3-d model of hydrodynamics and Alexandrium fundyense in an estuarine embayment has been developed to investigate the physical and biological controls on a recurrent harmful algal bloom. Nauset estuary on Cape Cod (MA, USA) consists of three salt ponds connected to the ocean through a shallow marsh and network of tidal channels. The model is evaluated using quantitative skill metrics against observations of physical and biological conditions during three spring blooms. The A. fundyense model is based on prior model applications for the nearby Gulf of Maine, but notable modifications were made to be consistent with the Nauset observations. The dominant factors controlling the A. fundyense bloom in Nauset were the water temperature, which regulates organism growth rates, and the efficient retention of cells due to bathymetric constraints, stratification, and cell behavior (diel vertical migration). Spring-neap variability in exchange altered residence times, but for cell retention to be substantially longer than the cell doubling time required both active vertical migration and stratification that inhibits mixing of cells into the surface layer by wind and tidal currents. Unlike in the Gulf of Maine, the model results were relatively insensitive to cyst distributions or germination rates. Instead, in Nauset, high apparent rates of vegetative cell division by retained populations dictated bloom development. Cyst germination occurred earlier in the year than in the Gulf of Maine, suggesting that Nauset cysts have different controls on germination timing. The model results were relatively insensitive to nutrient concentrations, due to eutrophic conditions in the highly impacted estuary or due to limitations in the spatial and temporal resolution of nutrient sampling. Cell loss rates were inferred to be extremely low during the growth phase of the bloom, but increased rapidly during the final phase due to processes that remain uncertain. The validated model allows a quantitative assessment of the factors that contribute to the development of a recurrent harmful algal bloom and provides a framework for assessing similarly impacted coastal systems.

Ecosystem legacy of the introduced N2-fixing tree Robinia pseudoacacia in a coastal forest.

Habitat invasibility has been found to increase dramatically following the alteration of ecosystem properties by a nonnative species. Robinia pseudoacacia, black locust, is a nitrogen-fixing, clonal tree species that aggressively invades open habitats and expands outside of plantations worldwide. Robinia pseudoacacia stands in Cape Cod National Seashore were particularly susceptible to a hurricane in 1991 that caused widespread blowdown and a dramatic reduction in Robinia in some stands. We used this change to investigate the lasting ecological effects of this nonnative species on this upland coastal ecosystem. We established replicate clusters of 20 × 20 m field plots within 50 m of each other that contained native pitch pine (Pinus rigida) and oak (Quercus velutina, Q. alba) forest, living Robinia stands, and stands in which Robinia was eliminated or reduced to less than 5% cover by the hurricane. Net nitrification and extractable soil nitrate concentration differed significantly between stand types, in the order Robinia > former Robinia > pine-oak. Nonnative species cover differed significantly between each stand type, in the order Robinia > former Robinia > pine-oak. Invasion of Robinia pseudoacacia increased soil net nitrification and nitrogen availability and precipitated a change in forest species composition that favored nonnative species. The presence of elevated soil nitrogen and nonnative species persisted at least 14 years after the removal of the original invading tree species, suggesting that the invasion of a tree species left a legacy of altered soil biogeochemistry, a higher number of nonnative species, and greater nonnative species cover.

A dual-spectrometer approach to reflectance measurements under sub-optimal sky conditions.

This paper presents a practical method for the development of spectral reflectance libraries under sub-optimal sky conditions. Although there are commercially available spectrometers which simultaneously measure both downwelling and upwelling radiance to mitigate the impact of sub-optimal sky conditions, these spectrometers only record in the visible and near infra-red. There are presently no commercially available spectrometers with this capability that can record the visible through short-wave infra-red. This paper presents a practical method of recording and processing data using coordinated measurements from two full-range spectrometers and discusses potential pitfalls and solutions required to achieve accurate reflectance spectra. Results demonstrate that high-quality spectral reflectance libraries can be developed with this approach.

Método para avaliação da mastigação unilateral na dentadura mista / Method for evaluating unilateral mastication in mixed dentition

A mastigação unilateral é, muitas vezes, o resultado da adaptação funcional a alterações que impedem movimentos suaves durante as excursões laterais da mandíbula. A literatura apresenta inúmeros trabalhos relatando consequências negativas nas estruturas faciais, tais como nos músculos mastigatórios, nas superfícies oclusais e na articulação temporomandibular, decorrente da mastigaçãounilateral.O método mais conhecido para a avaliação da mastigação unilateral é o método clínico. Com o advento de softwares para confecção de modelos computadorizados, uma nova realidade na avaliação da mastigação unilateral pode estar surgindo. O objetivo deste estudo foi comparar o método computadorizado (OrthoCAD) ao método clínico de avaliação da mastigaçãounilateral.A amostra foi composta de 15 indivíduos na fase de dentadura mista, sem cáries ou restaurações anteriores. O ângulo funcional mastigatório planas (AFMP) foi avaliado a partir de imagens fotográficas dos pacientes e modelos computadorizados produzido pelo programa OrthoCAD, em máxima íntercuspidação (MIC), excursão lateral direita (LD) e esquerda (LE). Comos resultados da comparação entre estes métodos pelo one-sample t-test, concluiu-se que o método clínico se mostra mais preciso para a avaliação da mordida unilateral.

Unilateral mastication is often the result of adaptation to disturbances which hinder smooth jaw movements during excursion. The literature presents several negative effects of unilateral mastication on facial structures such as masticatory muscles, occlusal surfaces and temporomandibular joint. The clinical Method is the most known to evaluate the unilateral mastication. A new reality for this evaluation could be emerging with the raise of softwares that creates computerized models. The purpose of this study was to compare the OrthoCAD method to the clinical method to evaluate the unilateral mastication. Fifteen subjects in the mixed dentition stage with no caries or previous restorations were used to compare these two techniques. measurements of the planas functional masticatory angle (PFMA) were made from patient photographs as well as computerized models produced by OrthoCAD in maximum lntercuspation, right and left lateral excursion. Resulting values were compared by one-sample t-test and it was concluded that the clinical method seen to be more accurate to evaluate the unilateral mastication.

Bond failure rates for V-loop vs straight wire lingual retainers.

INTRODUCTION: The V-loop bonded lingual retainer is an innovative design that allows the patient to floss with ease, a significant advantage over the conventional straight wire design for interproximal plaque control. The aim of this retrospective study was to compare the efficacy of straight wire and V-loop fixed retainers with respect to detachment rate when used to stabilize maxillary or mandibular anterior teeth after orthodontic treatment. METHODS: Fixed, customized retainers were placed in 300 patients and followed for 6 months. The conventional retainer system was a .0175-in stainless steel multi-stranded wire placed as a straight, bonded lingual retainer. The newer system was a .016-in stainless steel black Australian wire placed in a V-loop design. RESULTS: The detachment rates were 14.3% for the V-loop design and 12.4% for the straight wire retainer. The difference was not statistically significant. CONCLUSIONS: The V-loop retainer system addresses cleanability and physiologic adaptability, both critical for the clinical success of bonded lingual retainers used for long-term retention. The interdental wire span of the V-loop design allows easier access for flossing and sufficient flexibility for independent tooth movement in the periodontal space. Patient acceptance of the V-loop bonded lingual retainer was excellent, and most patients in this study found the retainer comfortable and easy to floss.