Search results for "M response"
showing 10 items of 78 documents
Environmental responses of past and recent agropastoral activities on south Greenlandic ecosystems through molecular biomarkers
2016
Paleoenvironmental studies previously performed on Lake Igaliku revealed two agropastoral phases in south Greenland: the Norse settlement from AD 986 to ca. AD 1450 and the recent installation of sheep farmers, since the 1920s. To improve the knowledge of the timing and magnitude of the Greenlandic agropastoral activities, a lipid inventory was realized and compared with biological and geochemical data. During the 12th century, a major increase in deoxycholic acid (DOC) and coprophilous fungal spores revealed a maximum of herbivores. Synchronously, a minimum of the n-C29/ n-C31 alkane ratio and tree and shrub pollen and a maximum of triterpenyl acetates showed a reduction in the tree and s…
Ecosystem responses to increased organic carbon concentration: comparing results based on long-term monitoring and whole-lake experimentation
2019
Recent increases in terrestrial dissolved organic carbon (DOC) concentrations in northern inland waters have many ecological consequences. We examined available data on carbon cycles and food webs of 2 boreal headwater lakes in southern Finland. Basic limnology and catchment characteristics of a pristine lake, Valkea-Kotinen (VK), were monitored over the past 25 years while the lake has undergone browning and DOC increased from similar to 11 to 13 mg L-1. Pronounced changes in the early 2000s represent a regime shift in DOC concentration and color. Lake Alinen Mustajarvi (AM) was manipulated for 2 years by additions of labile DOC (cane sugar), raising the DOC concentration from similar to 1…
Variational Approximations for Generalized Linear Latent Variable Models
2017
Generalized linear latent variable models (GLLVMs) are a powerful class of models for understanding the relationships among multiple, correlated responses. Estimation, however, presents a major challenge, as the marginal likelihood does not possess a closed form for nonnormal responses. We propose a variational approximation (VA) method for estimating GLLVMs. For the common cases of binary, ordinal, and overdispersed count data, we derive fully closed-form approximations to the marginal log-likelihood function in each case. Compared to other methods such as the expectation-maximization algorithm, estimation using VA is fast and straightforward to implement. Predictions of the latent variabl…
Developing common protocols to measure tundra herbivory across spatial scales
2021
Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, applied and assessed standardized protocols to measure tundra herbivory at three spatial scales: plot, site (habitat), and study area (landscape). The plot and site-level protocols were tested in the field during summers 2014-2015 at eleven sites, nine of them comprising warming experimental plots included in the International Tundra Experiment (ITEX). The study area protocols were assessed during 2014-2018 at 24 study areas across the Arctic. Our protocols provide comparable a…
Psychometric properties of the Satisfaction with Job Life Scale in Portuguese workers: A systematic study based on the IRT and CFA modeling
2020
Job satisfaction is related to better physical and mental health, as well as to factors specifically related to work. In this context, the measurement of work satisfaction is important for organizations that profess an interest in engaged and satisfied workers. Therefore, this study aims to examine the psychometric properties of the Satisfaction with Job Life Scale (SWJLS) in Portuguese workers by combining the procedures of the Classical Test Theory (CTT) and the Item Response Theory (IRT). Specifically, internal structure of the scale was studied, its reliability (consistency), correlations with other measures of wellbeing (life satisfaction, loneliness, emotional wellbeing at work, and j…
Quantity language speakers show enhanced subcortical processing
2016
Abstract The complex auditory brainstem response (cABR) can reflect language-based plasticity in subcortical stages of auditory processing. It is sensitive to differences between language groups as well as stimulus properties, e.g. intensity or frequency. It is also sensitive to the synchronicity of the neural population stimulated by sound, which results in increased amplitude of wave V. Finnish is a full-fledged quantity language, in which word meaning is dependent upon duration of the vowels and consonants. Previous studies have shown that Finnish speakers have enhanced behavioural sound duration discrimination ability and larger cortical mismatch negativity (MMN) to duration change comp…
Visual Working Memory Requires Permissive and Instructive NO/cGMP Signaling at Presynapses in the Drosophila Central Brain.
2017
The gaseous second messenger nitric oxide (NO) has been shown to regulate memory formation by activating retrograde signaling cascades from post- to presynapse that involve cyclic guanosine monophosphate (cGMP) production to induce synaptic plasticity and transcriptional changes. In this study, we analyzed the role of NO in the formation of a visual working memory that lasts only a few seconds. This memory is encoded in a subset of ring neurons that form the ellipsoid body in the Drosophila brain. Using genetic and pharmacological manipulations, we show that NO signaling is required for cGMP-mediated CREB activation, leading to the expression of competence factors like the synaptic homer pr…
The Stress-Inducible Protein DRR1 Exerts Distinct Effects on Actin Dynamics.
2018
Cytoskeletal dynamics are pivotal to memory, learning, and stress physiology, and thus psychiatric diseases. Downregulated in renal cell carcinoma 1 (DRR1) protein was characterized as the link between stress, actin dynamics, neuronal function, and cognition. To elucidate the underlying molecular mechanisms, we undertook a domain analysis of DRR1 and probed the effects on actin binding, polymerization, and bundling, as well as on actin-dependent cellular processes. Methods: DRR1 domains were cloned and expressed as recombinant proteins to perform in vitro analysis of actin dynamics (binding, bundling, polymerization, and nucleation). Cellular actin-dependent processes were analyzed in trans…
Absence of Early Neuronal Death in the Olivocochlear System Following Acoustic Overstimulation
2015
This study was conducted to examine possible effects of noise trauma on olivocochlear (OC) neurons. Anesthetized rats were exposed to a continuous 10 kHz pure tone at 120 dB sound pressure level for 2 hrs. The effects of treatment were verified by recordings of auditory brainstem response and distortion product otoacoustic emission. Three or 8 days after acoustic trauma, rats received unilateral injections of an aqueous solution of the retrograde neuronal tracer Fluorogold (FG) into the scala tympani to identify OC neurons (OCN). Five days after FG injection, brains were perfusion-fixed, and brainstem sections were cut and analyzed with respect to FG-labeled neurons. We found that, in both …
The measurement of populist attitudes: Testing cross-national scales using item response theory
2019
Recent research in the populism literature has devoted considerable efforts to the conceptualisation and examination of populism on the individual level, that is, populist attitudes. Despite rapid progress in the field, questions of adequate measurement and empirical evaluation of measures of populist attitudes remain scarce. Seeking to remedy these shortcomings, we apply a cross-national measurement model, using item response theory, to six established and two new populist indicators. Drawing on a cross-national survey (nine European countries, n = 18,368), we engage in a four-folded analysis. First, we examine the commonly used 6-item populism scale. Second, we expand the measurement wit…