Origin and Early Evolution of Hydrocharitaceae and the Ancestral Role of Stratiotes.

The combined morphological features of Stratiotes (Hydrocharitaceae) pollen, observed with light and electron microscopy, make it unique among all angiosperm pollen types and easy to identify. Unfortunately, the plant is (and most likely was) insect-pollinated and produces relatively few pollen grains per flower, contributing to its apparent absence in the paleopalynological record. Here, we present fossil Stratiotes pollen from the Eocene of Germany (Europe) and Kenya (Africa), representing the first reliable pre-Pleistocene pollen records of this genus worldwide and the only fossils of this family discovered so far in Africa. The fossil Stratiotes pollen grains are described and compared to pollen from a single modern species, Stratiotes aloides L. The paleophytogeographic significance and paleoecological aspects of these findings are discussed in relation to the Hydrocharitaceae fossil records and molecular phylogeny, as well as the present-day distribution patterns of its modern genera.

Database-based Eco-Plant analysis for Mesozoic dispersed sporomorphs.

Patterns of community assemblage for plants are associated with particular climatic elements such as water, heat, light, and air. The classification based on these plant assemblages is referred to here as the ecogroup of plants (Eco-Plant), whereas the method of analysing palaeoenvironmental and palaeoclimate variation by using Eco-Plant is called the Eco-Plant model. The online database Sporopollen was created to quickly assign eco-climatic traits to quantitative fossil sporomorph data to assess implications for past vegetation patterns and climatic changes. A user-friendly interface has been created, where users can upload their data to the database and in return get immediate results. This database can automatically link all Mesozoic and Cenozoic sporomorphs to their putative parent plants at phylum, order, or family level. It can also automatically link all Triassic and Jurassic sporomorphs to Eco-Plant groups to assess the effect of humidity (EPH) and the effect of temperature (EPT).•The Eco-Plant model allows to reconstruction of relative Triassic and Jurassic humidity and temperature changes.•A useful tool for palaeoenvironmental reconstruction.•A useful tool for (high-resolution) palynological studies.

Greenhouse conditions in lower Eocene coastal wetlands?-Lessons from Schöningen, Northern Germany.

The Paleogene succession of the Helmstedt Lignite Mining District in Northern Germany includes coastal peat mire records from the latest Paleocene to the middle Eocene at the southern edge of the Proto-North Sea. Therefore, it covers the different long- and short-term climate perturbations of the Paleogene greenhouse. 56 samples from three individual sections of a lower Eocene seam in the record capture the typical succession of the vegetation in a coastal wetland during a period that was not affected by climate perturbation. This allows facies-dependent vegetational changes to be distinguished from those that were climate induced. Cluster analyses and NMDS of well-preserved palynomorph assemblages reveal four successional stages in the vegetation during peat accumulation: (1) a coastal vegetation, (2) an initial mire, (3) a transitional mire, and (4) a terminal mire. Biodiversity measures show that plant diversity decreased significantly in the successive stages. The highly diverse vegetation at the coast and in the adjacent initial mire was replaced by low diversity communities adapted to wet acidic environments and nutrient deficiency. The palynomorph assemblages are dominated by elements such as Alnus (Betulaceae) or Sphagnum (Sphagnaceae). Typical tropical elements which are characteristic for the middle Eocene part of the succession are missing. This indicates that a more warm-temperate climate prevailed in northwestern Germany during the early lower Eocene.

Complex tracer diffusion dynamics in polymer solutions.

We employ fluorescence correlation spectroscopy (FCS) and coarse-grained molecular dynamics simulations to study the mobility of tracers in polymer solutions. Excluded volume interactions result in crowding-induced slowdown, depending only on the polymer concentration. With specific tracer-polymer attractions, the tracer is slowed down at much lower concentrations, and a second diffusion component appears that is sensitive to the polymer chain length. The two components can be resolved by FCS, only if the distance traveled by the tracer in the polymer-bound state is greater than the FCS focal spot size. The tracer dynamics can be used as a sensitive probe of the nature and strength of interactions, which-despite their local character-emphasize the role of chain connectivity.

Myotonic dystrophy type 1 presenting with stroke-like episodes: a case report.

BACKGROUND: It is well known that myotonic dystrophy type 1 (DM1)--Curschmann-Steinert disease--is associated with white matter lesions in the brain. Further, DM1 patients may suffer from cardiac involvement and cardioembolic strokes. We report on the unique case of an adult-onset DM1 without cardiac or vascular abnormalities presenting with stroke-like episodes. CASE PRESENTATION: A 40 y old white female was admitted twice to our stroke unit with apoplectic dizziness, nausea, headaches, and numbness in the right arm. She was suffering from type 2 diabetes, cataract, and endometriosis. Magnetic resonance imaging (MRI) revealed confluent white matter lesions in all cerebral lobes. There was no hyperintensity on diffusion-weighted imaging (DWI) and no gadolinium enhancement. Cerebrospinal fluid was normal. Surprisingly, myotonic discharges were detected in electromyography (EMG). Genetic testing revealed 200 ± 10 CTG repeats in the dystrophia myotonica protein kinase (DMPK) gene on chromosome 19 and DM1 was diagnosed. CONCLUSIONS: DM1 may be the cause of cerebral white matter lesions. This is the first case of DM1 presenting with stroke-like episodes.

Comparison of scalable fast methods for long-range interactions.

Based on a parallel scalable library for Coulomb interactions in particle systems, a comparison between the fast multipole method (FMM), multigrid-based methods, fast Fourier transform (FFT)-based methods, and a Maxwell solver is provided for the case of three-dimensional periodic boundary conditions. These methods are directly compared with respect to complexity, scalability, performance, and accuracy. To ensure comparable conditions for all methods and to cover typical applications, we tested all methods on the same set of computers using identical benchmark systems. Our findings suggest that, depending on system size and desired accuracy, the FMM- and FFT-based methods are most efficient in performance and stability.

Structure of symmetric and asymmetric "ripple" phases in lipid bilayers.

We reproduce the symmetric and asymmetric "rippled" P(beta') states of lipid membranes by Monte Carlo simulations of a coarse-grained molecular model for lipid-solvent mixtures. The structure and properties compare favorably with experiments. The asymmetric ripple state is characterized by a periodic array of fully interdigitated "defect" lines. The symmetric ripple state maintains a bilayer structure, but is otherwise structurally similar. The main force driving the formation of both ripple states is the propensity of lipid molecules with large head groups to exhibit splay.

Heterogeneity of brain glucose metabolism in mild cognitive impairment and clinical progression to Alzheimer disease.

BACKGROUND: Subjects with amnesic mild cognitive impairment (aMCI) may include patients at high risk for progression to Alzheimer disease (AD) and a population with different underlying pathologic conditions. OBJECTIVE: To evaluate the potential roles of positron emission tomography with fluorodeoxyglucose F 18 (18FDG-PET) and memory scores in identifying subjects with aMCI and in predicting progression to dementia. DESIGN, SETTING, AND PATIENTS: Sixty-seven patients at European centers for neurologic and AD care who were diagnosed as having aMCI each underwent an extensive clinical and neuropsychological examination and an 18FDG-PET study. Forty-eight subjects were followed up periodically for at least 1 year, and progression to dementia was evaluated. MAIN OUTCOME MEASURES: Brain glucose metabolism and memory scores. RESULTS: Fourteen subjects with aMCI who converted to AD within 1 year showed bilateral hypometabolism in the inferior parietal, posterior cingulate, and medial temporal cortex. Subjects with "stable" aMCI presented with hypometabolism in the dorsolateral frontal cortex. The severity of memory impairment, as evaluated by the California Verbal Learning Test-Long Delay Free Recall scores, correlated with the following brain metabolic patterns: scores less than 7 were associated with a typical 18FDG-PET AD pattern, and scores of 7 or higher were associated with hypometabolism in the dorsolateral frontal cortex and no progression to AD. CONCLUSION: These data provide evidence for clinical and functional heterogeneity among subjects with aMCI and suggest that 18FDG-PET findings combined with memory scores may be useful in predicting short-term conversion to AD.

Regional cerebral metabolism in early Alzheimer's disease with clinically significant apathy or depression.

BACKGROUND: Alzheimer's disease (AD) is clinically characterized by cognitive impairment and behavioral disturbances. The aim of the study was to identify regional alterations in brain function associated with neuropsychiatric symptoms in early AD. METHODS: Patients underwent measures of cerebral glucose metabolism applying positron emission tomography (PET) and (18)F-fluorodeoxyglucose. Neuropsychiatric symptoms were assessed using the Neuropsychiatric Inventory (NPI). Positron emission tomography images of patients suffering a neuropsychiatric symptom of clinical significance (NPI subscore for a specific item >/=4 points) were compared with the images of patients without the specific symptom under study (NPI subscore for a specific item = 0 points). RESULTS: A total of 53 patients with AD (Mini-Mental State Examination [MMSE] 22.5 +/- 2.94 points) entered the study. Of all symptoms, apathy and depression were most frequently encountered. The patient group with apathy (n = 17) revealed significant decreases in left orbitofrontal regions when compared with patients free of apathy. Depression of clinical significance (n = 10) was associated with hypometabolism in dorsolateral prefrontal regions. CONCLUSIONS: These findings support the notion that different functional circuits underlie apathy and depression in early AD.