Complexity of diatom response to Lateglacial and Holocene climate and environmental change in ancient, deep and oligotrophic Lake Ohrid (Macedonia and Albania)

© Author(s) 2016. Lake Ohrid (Macedonia and Albania) is a rare example of a deep, ancient Mediterranean lake and is a key site for palaeoclimate research in the northeastern Mediterranean region. This study conducts the analysis of diatoms as a proxy for Lateglacial and Holocene climate and environmental change in Lake Ohrid at a higher resolution than in previous studies. While Lake Ohrid has the potential to be sensitive to water temperature change, the data demonstrate a highly complex diatom response, probably comprising a direct response to temperature-induced lake productivity in some phases and an indirect response to temperaturerelated lake stratification or mixing and epilimnetic nutrient availability in others. The data also demonstrate the possible influence of physical limnological (e.g. the influence of wind stress on stratification or mixing) and chemical processes (e.g. the influence of catchment dynamics on nutrient input) in mediating the complex response of diatoms. During the Lateglacial (ca. 12 300-11 800 cal yr BP), the low-diversity dominance of hypolimnetic Cyclotella fottii indicates low lake productivity, linked to low water temperature. Although the subsequent slight increase in small, epilimnetic C. minuscula during the earliest Holocene (ca. 11 800-10 600 cal yr BP) suggests climate warming and enhanced stratification, diatom concentration remains as low as during the Lateglacial, suggesting that water temperature increase was muted across this major transition. The early Holocene (ca. 10 600-8200 cal yr BP) is characterised by a sustained increase in epilimnetic taxa, with mesotrophic C. ocellata indicating high water-temperature-induced productivity between ca. 10 600-10 200 cal yr BP and between ca. 9500-8200 cal yr BP and with C. minuscula in response to low nutrient availability in the epilimnion between ca. 10 200-9500 cal yr BP. During the middle Holocene (ca. 8200-2600 cal yr BP), when sedimentological and geochemical proxies provide evidence for maximum Holocene water temperature, anomalously low C. ocellata abundance is probably a response to epilimnetic nutrient limitation, almost mimicking the Lateglacial flora apart from the occurrence of mesotrophic Stephanodiscus transylvanicus in the hypolimnion. During the late Holocene (ca. 2600 cal yr BP-present), high abundance and fluctuating composition of epilimnetic taxa are probably a response more to enhanced anthropogenic nutrient input, particularly nitrogen enrichment, than to climate. Overall, the data indicate that previous assumptions concerning the linearity of diatom response in this deep, ancient lake are invalid, and multi-proxy analysis is essential to improve understanding of palaeolimnological dynamics in future research on the long, Quaternary sequence

Seismic Modeling and Incremental Dynamic Analysis of the Cold-Formed Steel Framed CFS-NEES Building

The objective of this paper is to present seismic modeling of a two-story cold-formed steel (CFS) framed building. The selected building, known as the CFSNEES building, was designed to current U.S. standards and then subjected to full-scale shake table tests under the U.S. National Science Foundation Network for Earthquake Engineering Simulation (NEES) program. Test results showed that the building’s stiffness and capacity was considerably higher than expected and the building suffered only non-structural damage and no permanent drift, even at maximum considered earthquake (per ASCE 7 and the selected California site) level. Past modeling, including that of the authors, largely focused on nonlinear hysteretic modeling of the shear walls. The test results indicate that additional building elements must be considered to develop an accurate characterization of the strength, stiffness, and ductility of the building. Advanced 3D models were developed in OpenSees to accurately depict the lateral response and included all structural and non-structural framing and sheathing, explicit diaphragm modeling, and nonlinear boundary conditions to capture bearing load paths. This paper details the modeling techniques adopted and typical results including comparison with experiments. The impact of the various modeling assumptions on the results is also explored to provide a measure of system sensitivity. In addition, incremental dynamic analysis was performed on the building model and the results post-processed consistent with the FEMA P695 protocol. For the CFS-NEES building, designed to current standards, results indicate that the advanced model predicts an acceptable collapse margin ratio. In the future, the modeling protocols established here provide a means to analyze a suite of CFS-framed archetype buildings and provide further insight on seismic response modification coefficients

Seismic Computational Analysis of CFS-NEES Building

The objective of this paper is to explore computational modeling of a coldformed steel framed building subjected to earthquake excitation. The selected two-story building will be subjected to full-scale motion on a shaking table in 2013 as part of the National Science Foundation funded Cold-Formed Steel – Network for Earthquake Engineering Simulation (CFS-NEES) project. The ledger-framed building employs load bearing cold-formed steel members throughout (wall, floors, and roofs) and employs OSB sheathed shear walls and an OSB sheathed diaphragm for the lateral force resisting system. Two- and three-dimensional analysis models capable of providing vibration, pushover, linear and nonlinear time history analysis are created in OpenSees. To date, the key nonlinearity investigated in the models is the characterization of the shear walls. The shear walls are either modeled as (a) elastic perfectly plastic, consistent with “state of the practice” level knowledge from AISI-S213 or (b) fully hysteretic with pinching and strength degradation based on shear walls tests conducted specifically for this building. The impact of the diaphragm stiffness is also investigated. Interaction of the lateral and gravity system, interaction of the joists, ledger, and walls, and the impact of openings on the diaphragm all remain for future work. The model is being employed to help determine the predicted experimental performance and develop key sensor targets in the response. In addition, the model will be used in incremental dynamic analysis to explore seismic performance-based design and sensitivity to model fidelity (2D, 3D, etc.) for cold-formed steel framed buildings

Classification of Overlapped Audio Events Based on AT, PLSA, and the Combination of Them

Audio event classification, as an important part of Computational Auditory Scene Analysis, has attracted much attention. Currently, the classification technology is mature enough to classify isolated audio events accurately, but for overlapped audio events, it performs much worse. While in real life, most audio documents would have certain percentage of overlaps, and so the overlap classification problem is an important part of audio classification. Nowadays, the work on overlapped audio event classification is still scarce, and most existing overlap classification systems can only recognize one audio event for an overlap. In this paper, in order to deal with overlaps, we innovatively introduce the author-topic (AT) model which was first proposed for text analysis into audio classification, and innovatively combine it with PLSA (Probabilistic Latent Semantic Analysis). We propose 4 systems, i.e. AT, PLSA, AT-PLSA and PLSA-AT, to classify overlaps. The 4 proposed systems have the ability to recognize two or more audio events for an overlap. The experimental results show that the 4 systems perform well in classifying overlapped audio events, whether it is the overlap in training set or the overlap out of training set. Also they perform well in classifying isolated audio events

Magnetodielectric effect in nickel nanosheet-Na-4 mica composites

Nickel nanosheets of thickness 0.6 nm were grown within the nanochannels of Na-4 mica template. The specimens show magnetodielectric effect at room temperature with a change of dielectric constant as a function of magnetic field, the electric field frequency varying from 100 to 700 kHz. A decrease of 5% in the value of dielectric constant was observed up to a field of 1.2 Tesla. This is explained by an inhomogeneous two-component composite model as theoretically proposed recently. The present approach will open up synthesis of various nanocomposites for sensor applications.Comment: 11 pages, 7 figure

Velocity Map Imaging the Scattering Plane of Gas Surface Collisions

The ability of gas-surface dynamics studies to resolve the velocity distribution of the scattered species in the 2D sacattering plane has been limited by technical capabilities and only a few different approaches have been explored in recent years. In comparison, gas-phase scattering studies have been transformed by the near ubiquitous use of velocity map imaging. We describe an innovative means of introducing a surface within the electric field of a typical velocity map imaging experiment. The retention of optimum velocity mapping conditions was demonstrated by measurements of iodomethane-d3 photodissociation and SIMION calculations. To demonstrate the systems capabilities the velocity distributions of ammonia molecules scattered from a PTFE surface have been measured for multiple product rotational states.Comment: 8 pages, 5 figures, to be submitted to journa

The Effect of Moxidectin Treatment on the Equine Hind Gut Microbiome, Metabonome and Feed Fermentation Kinetics in Horses with Very Low Parasite Burdens

Seventeen horses, mean 12 ± 3.5 years, kept at pasture, with haylage provided and no concentrates. Faecal Egg Counts were conducted September 2015‐March 2016, no eggs seen, no anthelmintic given. Sampling commenced March 2016, points were 0 (prior), 16, 48 and 168 hours post anthelmintic. Treatments were randomized, nine animals dosed orally with Moxidectin 18.92 mg/g at 0.4 mg/kg bw and eight controls. Three horses from each group were randomly assigned for fermentation kinetics. Sequencing of the 16S rRNA gene was conducted on extracted faecal bacterial DNA, bioinformatics using QIIME assigning operational taxonomic units (OTUs). LEfSe (Segata et al., 2011) was used to identify differentially abundant OTUs. Bacterial metabolic profiles were characterized by 1H NMR spectroscopy (Escalona et al., 2015), from urine, analysed by Principal Components Analysis. Fermentation of hay and oats, separately, were measured by in vitro gas production (Murray et al., 2006), data were analysed by repeated measures ANOVA