3,843 research outputs found
Collaborative research: dynamics of ocean climate changes in the Gulf of Alaska
Issued as final reportNational Science Foundation (U.S
Thalamo-cortical network activity between migraine attacks. Insights from MRI-based microstructural and functional resting-state network correlation analysis
BACKGROUND:
Resting state magnetic resonance imaging allows studying functionally interconnected brain networks. Here we were aimed to verify functional connectivity between brain networks at rest and its relationship with thalamic microstructure in migraine without aura (MO) patients between attacks.
METHODS:
Eighteen patients with untreated MO underwent 3 T MRI scans and were compared to a group of 19 healthy volunteers (HV). We used MRI to collect resting state data among two selected resting state networks, identified using group independent component (IC) analysis. Fractional anisotropy (FA) and mean diffusivity (MD) values of bilateral thalami were retrieved from a previous diffusion tensor imaging study on the same subjects and correlated with resting state ICs Z-scores.
RESULTS:
In comparison to HV, in MO we found significant reduced functional connectivity between the default mode network and the visuo-spatial system. Both HV and migraine patients selected ICs Z-scores correlated negatively with FA values of the thalamus bilaterally.
CONCLUSIONS:
The present results are the first evidence supporting the hypothesis that an abnormal resting within networks connectivity associated with significant differences in baseline thalamic microstructure could contribute to interictal migraine pathophysiology
Uncovering the potential of blockchain in the agri-food supply chain. An interdisciplinary case study
This paper explores how Blockchain technology (BCT) can be integrated in the agri-food supply chain (ASC) and how BCT-based networks are formed. To do this, the paper describes a BCT solution, designed to enhance traceability, and analyses its adoption in two small firms. Adopting an interdisciplinary approach and the Actor-Network Theory (ANT), the findings have revealed that BCT improves how data is collected and has changed how firms interact with stakeholders and customers. Firms have enhanced their reputations and started targeting new domestic and international markets. Technical and economic challenges were found when persuading actors to participate in the BCT-based network
Advances in Marine Ecosystem Dynamics from US GLOBEC: The Horizontal-Advection Bottom-up Forcing Paradigm
A primary focus of the US Global Ocean Ecosystem Dynamics (GLOBEC) program was to identify the mechanisms of ecosystem response to large- scale climate forcing under the assumption that bottom-up forcing controls a large fraction of marine ecosystem variability. At the beginning of GLOBEC, the prevailing bottom-up forcing hypothesis was that climate-induced changes in vertical transport modulated nutrient supply and surface primary productivity, which in turn affected the lower trophic levels (e.g., zooplankton) and higher trophic levels (e.g., fish) through the trophic cascade. Although upwelling dynamics were confirmed to be an important driver of ecosystem variability in GLOBEC studies, the use of eddy- resolving regional-scale ocean circulation models combined with field observations revealed that horizontal advection is an equally important driver of marine ecosystem variability. Trough a synthesis of studies from the four US GLOBEC regions (Gulf of Alaska, Northern California Current, Northwest Atlantic, and Southern Ocean), a new horizontal-advection bottom-up forcing paradigm emerges in which large-scale climate forcing drives regional changes in alongshore and cross-shelf ocean transport that directly impact ecosystem functions (e.g., productivity, species composition, spatial connectivity). Te horizontal advection bottom-up forcing paradigm expands the mechanistic pathways through which climate variability and climate change impact the marine ecosystem. In particular, these results highlight the need for future studies to resolve and understand the role of mesoscale and submesoscale transport processes and their relationship to climate
Advances in Marine Ecosystem Dynamics from US GLOBEC: The Horizontal-Advection Bottom-up Forcing Paradigm
A primary focus of the US Global Ocean Ecosystem Dynamics (GLOBEC) program was to identify the mechanisms of ecosystem response to large- scale climate forcing under the assumption that bottom-up forcing controls a large fraction of marine ecosystem variability. At the beginning of GLOBEC, the prevailing bottom-up forcing hypothesis was that climate-induced changes in vertical transport modulated nutrient supply and surface primary productivity, which in turn affected the lower trophic levels (e.g., zooplankton) and higher trophic levels (e.g., fish) through the trophic cascade. Although upwelling dynamics were confirmed to be an important driver of ecosystem variability in GLOBEC studies, the use of eddy- resolving regional-scale ocean circulation models combined with field observations revealed that horizontal advection is an equally important driver of marine ecosystem variability. Trough a synthesis of studies from the four US GLOBEC regions (Gulf of Alaska, Northern California Current, Northwest Atlantic, and Southern Ocean), a new horizontal-advection bottom-up forcing paradigm emerges in which large-scale climate forcing drives regional changes in alongshore and cross-shelf ocean transport that directly impact ecosystem functions (e.g., productivity, species composition, spatial connectivity). Te horizontal advection bottom-up forcing paradigm expands the mechanistic pathways through which climate variability and climate change impact the marine ecosystem. In particular, these results highlight the need for future studies to resolve and understand the role of mesoscale and submesoscale transport processes and their relationship to climate
Cerebral gray matter volume in patients with chronic migraine: correlations with clinical features
Abstract
Background
To date, few MRI studies have been performed in patients affected by chronic migraine (CM), especially in those without medication overuse. Here, we performed magnetic resonance imaging (MRI) voxel-based morphometry (VBM) analyses to investigate the gray matter (GM) volume of the whole brain in patients affected by CM. Our aim was to investigate whether fluctuations in the GM volumes were related to the clinical features of CM.
Methods
Twenty untreated patients with CM without a past medical history of medication overuse underwent 3-Tesla MRI scans and were compared to a group of 20 healthy controls (HCs). We used SPM12 and the CAT12 toolbox to process the MRI data and to perform VBM analyses of the structural T1-weighted MRI scans. The GM volume of patients was compared to that of HCs with various corrected and uncorrected thresholds. To check for possible correlations, patients’ clinical features and GM maps were regressed.
Results
Initially, we did not find significant differences in the GM volume between patients with CM and HCs (p < 0.05 corrected for multiple comparisons). However, using more-liberal uncorrected statistical thresholds, we noted that compared to HCs, patients with CM exhibited clusters of regions with lower GM volumes including the cerebellum, left middle temporal gyrus, left temporal pole/amygdala/hippocampus/pallidum/orbitofrontal cortex, and left occipital areas (Brodmann areas 17/18). The GM volume of the cerebellar hemispheres was negatively correlated with the disease duration and positively correlated with the number of tablets taken per month.
Conclusion
No gross morphometric changes were observed in patients with CM when compared with HCs. However, using more-liberal uncorrected statistical thresholds, we observed that CM is associated with subtle GM volume changes in several brain areas known to be involved in nociception/antinociception, multisensory integration, and analgesic dependence. We speculate that these slight morphometric impairments could lead, at least in a subgroup of patients, to the development and continuation of maladaptive acute medication usage
Low-frequency variability in the Gulf of Alaska from coarse and eddy-permitting ocean models
[1] An eddy-permitting ocean model of the northeast Pacific is used to examine the ocean adjustment to changing wind forcing in the Gulf of Alaska (GOA) at interannual-to-decadal timescales. It is found that the adjustment of the ocean model in the presence of mesoscale eddies is similar to that obtained with coarse-resolution models. Local Ekman pumping plays a key role in forcing pycnocline depth variability and, to a lesser degree, sea surface height (SSH) variability in the center of the Alaska gyre and in some areas of the eastern and northern GOA. Westward Rossby wave propagation is evident in the SSH field along some latitudes but is less noticeable in the pycnocline depth field. Differences between SSH and pycnocline depth are also found when considering their relationship with the local forcing and leading modes of climate variability in the northeast Pacific. In the central GOA pycnocline depth variations are more clearly related to changes in the local Ekman pumping than SSH. While SSH is marginally correlated with both Pacific Decadal Oscillation (PDO) and North Pacific Gyre Oscillation (NPGO) indices, the pycnocline depth evolution is primarily related to NPGO variability. The intensity of the mesoscale eddy field increases with increasing circulation strength. The eddy field is generally more energetic after the 1976–1977 climate regime shift, when the gyre circulation intensified. In the western basin, where eddies primarily originate from intrinsic instabilities of the flow, variations in eddy kinetic energy are statistically significant correlated with the PDO index, indicating that eddy statistics may be inferred, to some degree, from the characteristics of the large-scale flow
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Interannual variability of the subsurface eddy field in the Southeast Pacific
The Southeast Pacific, which encompasses the coasts of Peru and Chile, is one of the world's most productive regions resulting principally from the upwelling of subsurface nutrient-rich waters. Over the satellite altimetry era, there have been numerous evidence that surface mesoscale eddies play an important role in the offshore transport of rich coastal waters, but it has been only recently that few observational/numerical studies have highlighted the importance of the subsurface eddies. The eddy field variability is explored using the results of a high-resolution model experiment from 1979 to 2012. The model results indicate an asymmetry of the surface and subsurface eddy fields. While surface-intensified cyclones are slightly more frequent than anticyclones, the subsurface field is dominated by anticyclones (IntrathermoclineEddies; ITEs), triggered by the instability of the subsurface Peru Chile undercurrent (PCUC). Composite maps are consistent with in situ observations. ITEs are associated with maximum vorticity around 150–200 m depth, warmer and more saline core, characteristic of the equatorial subsurface water from the PCUC. We find that the variability of the ITEs is significantly correlated with the ENSO equatorial signal. During strong El Niño events (e.g., 1982; 1998), we find that while the PCUC transport increases, the volume of coastal waters transported by ITEs however decreases during those periods. We find that the relaxation of the isopycnals along the coast during El Niño events leads to weakened baroclinic instability and to a decrease of the ITEs transport.This is the publisher’s final pdf. The article is copyrighted by American Geophysical Union and published by John Wiley & Sons Inc. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/%28ISSN%292169-9291
Hallux rigidus: current concepts review and treatment algorithm with special focus on interposition arthroplasty
Hallux rigidus represents a surgical challenge, with a multitude of possible surgical options, but with no ideal procedures. The propose of this paper was to review the actual knowledge on the operative techniques, paying particular attention to the evolution of interposition arthroplasties, as an alternative to arthrodesis and prosthesis in the advanced stages of the disease
Case report: “Scared to deaf”: medical-legal evaluation of a suspected post -traumatic stress disorder”
The case concerns the alleged failure by the resisting administration to fulfill obligations arising from the contract and employment relationship, as well as the violation of safety regulations leading to the workplace accident reported by an Airforce Sergeant. Following the accident, the soldier complains of developing barotraumatic hearing loss with tinnitus and reactive post-traumatic stress disorder to the traumatic event. The case provides an opportunity to analyze the relevance of forensic medical assessment and its integration with psychodiagnostic examination for the correct nosographic classification aimed at evaluating and quantifying biological damage
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