Density Dependence Drives Habitat Production and Survivorship of Acropora cervicornis Used for Restoration on a Caribbean Coral Reef

Coral restoration is gaining traction as a viable strategy to help restore degraded reefs. While the nascent field of coral restoration has rapidly progressed in the past decade, significant knowledge gaps remain regarding the drivers of restoration success that may impede our ability to effectively restore coral reef communities. Here, we conducted a field experiment to investigate the influence of coral density on the growth, habitat production, and survival of corals outplanted for restoration. We used nursery-raised colonies of Acropora cervicornis to experimentally establish populations of corals with either 3, 6, 12, or 24 corals within 4m2 plots, generating a gradient of coral densities ranging from 0.75 corals m−2 to 12 corals m−2. After 13 months we found that density had a significant effect on the growth, habitat production, and survivorship of restored corals. We found that coral survivorship increased as colony density decreased. Importantly, the signal of density dependent effects was context dependent. Our data suggest that positive density dependent effects influenced habitat production at densities of 3 corals m−2, but further increases in density resulted in negative density dependent effects with decreasing growth and survivorship of corals. These findings highlight the importance of density dependence for coral restoration planning and demonstrate the need to evaluate the influence of density for other coral species used for restoration. Further work focused on the mechanisms causing density dependence such as increased herbivory, rapid disease transmission, or altered predation rates are important next steps to advance our ability to effectively restore coral reefs

Разработка метода формирования износостойких поверхностных слоев в технически чистом алюминии

Объектом исследования является технически чистый алюминий марки А7, подвергнутый азотированию в плазме несамостоятельного частотно-импульсного тлеющего разряда с полым катодом при низком давлении. Цель работы – разработка метода формирования износостойких поверхностных слоев в технически чистом алюминии. Проведены исследования механических и трибологических свойств материала (микротвердость, коэффициент износа, коэффициент трения). В результате исследования выявлен режим азотирования, позволяющий кратно повысить трибологические и механических характеристики технически чистого алюминия марки А7.The subject of the study is technically pure aluminum of the A7, subjected to nitriding in the plasma of a frequency-pulse non-self-sustained glow discharge with a hollow cathode at low pressure. The aim of the work is to development of a method for the formation of wear-resistant surface layers in technically pure aluminum. Mechanical and tribological properties of the material (microhardness, wear coefficient, coefficient of friction) are studied. As a result of the study, the nitriding mode was revealed, which allows to increase the tribological and mechanical characteristics of technically pure aluminum of the A7

Multiparametric MRI for Characterization of the Basal Ganglia and the Midbrain

Objectives To characterize subcortical nuclei by multi-parametric quantitative magnetic resonance imaging.Materials and Methods: The following quantitative multiparametric MR data of five healthy volunteers were acquired on a 7T MRI system: 3D gradient echo (GRE) data for the calculation of quantitative susceptibility maps (QSM), GRE sequences with and without off-resonant magnetic transfer pulse for magnetization transfer ratio (MTR) calculation, a magnetization−prepared 2 rapid acquisition gradient echo sequence for T1 mapping, and (after a coil change) a density-adapted 3D radial pulse sequence for 23Na imaging. First, all data were co-registered to the GRE data, volumes of interest (VOIs) for 21 subcortical structures were drawn manually for each volunteer, and a combined voxel-wise analysis of the four MR contrasts (QSM, MTR, T1, 23Na) in each structure was conducted to assess the quantitative, MR value-based differentiability of structures. Second, a machine learning algorithm based on random forests was trained to automatically classify the groups of multi-parametric voxel values from each VOI according to their association to one of the 21 subcortical structures.Results The analysis of the integrated multimodal visualization of quantitative MR values in each structure yielded a successful classification among nuclei of the ascending reticular activation system (ARAS), the limbic system and the extrapyramidal system, while classification among (epi-)thalamic nuclei was less successful. The machine learning-based approach facilitated quantitative MR value-based structure classification especially in the group of extrapyramidal nuclei and reached an overall accuracy of 85% regarding all selected nuclei.Conclusion Multimodal quantitative MR enabled excellent differentiation of a wide spectrum of subcortical nuclei with reasonable accuracy and may thus enable sensitive detection of disease and nucleus-specific MR-based contrast alterations in the future

Editorial : Innovations in MR Hardware from Ultra-Low to Ultra-High Field

Peer reviewedPublisher PD

Seismic and acoustic signal identification algorithms

ABSTRACT This paper will describe an algorithm for detecting and classi&ing seismic and acoustic signals for unattended ground sensors. The algorithm must be computationally eftlcient and continuously process a data stream in order to establish whether or not a desired signal has changed state (turned-on or ofl). The paper will focus on describing a Fourier based technique that compares the running power spectral density estimate of the data to a predetermined signature in order to determine if the desired signal has changed state. How to establish the signature and the detection thresholds will be discussed as well as the theoretical statistics of the algorithm for the Gaussian noise case with results from simulated data. Actual seismic data results will also be discussed along with techniques used to reduce false alarms due to the inherent nonstationary noise environments found with actual data

Structural and functional MRI abnormalities of cerebellar cortex and nuclei in SCA3, SCA6 and Friedreich\u27s ataxia

Spinocerebellar ataxia type 3, spinocerebellar ataxia type 6 and Friedreich\u27s ataxia are common hereditary ataxias. Different patterns of atrophy of the cerebellar cortex are well known. Data on cerebellar nuclei are sparse. Whereas cerebellar nuclei have long been thought to be preserved in spinocerebellar ataxia type 6, histology shows marked atrophy of the nuclei in Friedreich\u27s ataxia and spinocerebellar ataxia type 3. In the present study susceptibility weighted imaging was used to assess atrophy of the cerebellar nuclei in patients with spinocerebellar ataxia type 6 (n = 12, age range 41-76 years, five female), Friedreich\u27s ataxia (n = 12, age range 21-55 years, seven female), spinocerebellar ataxia type 3 (n = 10, age range 34-67 years, three female), and age-and gender-matched controls (total n = 23, age range 22-75 years, 10 female). T1-weighted magnetic resonance images were used to calculate the volume of the cerebellum. In addition, ultra-high field functional magnetic resonance imaging was performed with optimized normalization methods to assess function of the cerebellar cortex and nuclei during simple hand movements. As expected, the volume of the cerebellum was markedly reduced in spinocerebellar ataxia type 6, preserved in Friedreich\u27s ataxia, and mildy reduced in spinocerebellar ataxia type 3. The volume of the cerebellar nuclei was reduced in the three patient groups compared to matched controls (P-values \u3c 0.05; two-sample t-tests). Atrophy of the cerebellar nuclei was most pronounced in spinocerebellar ataxia type 6. On a functional level, hand-movement-related cerebellar activation was altered in all three disorders. Within the cerebellar cortex, functional magnetic resonance imaging signal was significantly reduced in spinocerebellar ataxia type 6 and Friedreich\u27s ataxia compared to matched controls (P-values \u3c 0.001, bootstrap-corrected cluster-size threshold; two-sample t-tests). The difference missed significance in spinocerebellar ataxia type 3. Within the cerebellar nuclei, reductions were significant when comparing spinocerebellar ataxia type 6 and Friedreich\u27s ataxia to matched controls (P \u3c 0.01, bootstrap-corrected cluster-size threshold; two-sample t-tests). Susceptibility weighted imaging allowed depiction of atrophy of the cerebellar nuclei in patients with Friedreich\u27s ataxia and spinocerebellar ataxia type 3. In spinocerebellar ataxia type 6, pathology was not restricted to the cerebellar cortex but also involved the cerebellar nuclei. Functional magnetic resonance imaging data, on the other hand, revealed that pathology in Friedreich\u27s ataxia and spinocerebellar ataxia type 3 is not restricted to the cerebellar nuclei. There was functional involvement of the cerebellar cortex despite no or little structural changes