67 research outputs found
Rogue Trends in Sovereign Debt: Argentina, Vulture Funds, and Pari Passu Under New York Law
Mapping gray and white matter volume abnormalities in early-onset psychosis: an ENIGMA multicenter voxel-based morphometry study
Introduction: Regional gray matter (GM) alterations have been reported in early-onset psychosis (EOP, onset before age 18), but previous studies have yielded conflicting results, likely due to small sample sizes and the different brain regions examined. In this study, we conducted a whole brain voxel-based morphometry (VBM) analysis in a large sample of individuals with EOP, using the newly developed ENIGMA-VBM tool. Methods: 15 independent cohorts from the ENIGMA-EOP working group participated in the study. The overall sample comprised T1-weighted MRI data from 482 individuals with EOP and 469 healthy controls. Each site performed the VBM analysis locally using the standardized ENIGMA-VBM tool. Statistical parametric T-maps were generated from each cohort and meta-analyzed to reveal voxel-wise differences between EOP and healthy controls as well as the individual-based association between GM volume and age of onset, chlorpromazine (CPZ) equivalent dose, and other clinical variables. Results: Compared with healthy controls, individuals with EOP showed widespread lower GM volume encompassing most of the cortex, with the most marked effect in the left median cingulate (Hedges’ g = 0.55, p = 0.001 corrected), as well as small clusters of lower white matter (WM), whereas no regional GM or WM volumes were higher in EOP. Lower GM volume in the cerebellum, thalamus and left inferior parietal gyrus was associated with older age of onset. Deficits in GM in the left inferior frontal gyrus, right insula, right precentral gyrus and right superior frontal gyrus were also associated with higher CPZ equivalent doses. Conclusion: EOP is associated with widespread reductions in cortical GM volume, while WM is affected to a smaller extent. GM volume alterations are associated with age of onset and CPZ equivalent dose but these effects are small compared to case-control differences. Mapping anatomical abnormalities in EOP may lead to a better understanding of the role of psychosis in brain development during childhood and adolescence
Quantum and Classical Ballistic Transport in Constricted Two-Dimensional Electron Gases
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
PAMELA/ATIC anomaly from the meta-stable extra dark matter component and the leptophilic Yukawa interaction
We present a supersymmetric model with two dark matter (DM) components
explaining the galactic positron excess observed by PAMELA/HEAT and
ATIC/PPB-BETS: One is the conventional (bino-like) lightest supersymmetric
particle (LSP) \chi, and the other is a TeV scale meta-stable neutral singlet
N_D, which is a Dirac fermion (N,N^c). In this model, N_D decays dominantly
into \chi e^+e^- through an R parity preserving dimension 6 operator with the
life time \tau_N\sim 10^{26} sec. We introduce a pair of vector-like superheavy
SU(2) lepton doublets (L,L^c) and lepton singlets (E,E^c). The dimension 6
operator leading to the N_D decay is generated from the leptophilic Yukawa
interactions by W\supset Ne^cE+Lh_dE^c+m_{3/2}l_1L^c with the dimensionless
couplings of order unity, and the gauge interaction by {\cal L}\supset \sqrt{2}
g'\tilde{e}^{c*}e^c\chi + h.c. The superheavy masses of the vector-like leptons
(M_L, M_E\sim 10^{16} GeV) are responsible for the longevity of N_D. The low
energy field spectrum in this model is just the MSSM fields and N_D. Even for
the case that the portion of N_D is much smaller than that of \chi in the total
DM density [{\cal O}(10^{-10}) \lesssim n_{N_D}/n_\chi], the observed positron
excess can be explained by adopting relatively lighter masses of the
vector-like leptons (10^{13} GeV \lesssim M_{L,E} \lesssim 10^{16} GeV). The
smallness of the electron mass is also explained. This model is easily embedded
in the flipped SU(5) grand unification, which is a leptophilic unified theory.Comment: 12 pages, published versio
The Forest Observation System, building a global reference dataset for remote sensing of forest biomass
International audienceForest biomass is an essential indicator for monitoring the Earth's ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (aGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. aGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world's forests. all plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities
Recommended from our members
Mapping gray and white matter volume abnormalities in early-onset psychosis: an ENIGMA multicenter voxel-based morphometry study
INTRODUCTION: Regional gray matter (GM) alterations have been reported in early-onset psychosis (EOP, onset before age 18), but previous studies have yielded conflicting results, likely due to small sample sizes and the different brain regions examined. In this study, we conducted a whole brain voxel-based morphometry (VBM) analysis in a large sample of individuals with EOP, using the newly developed ENIGMA-VBM tool.
METHODS: 15 independent cohorts from the ENIGMA-EOP working group participated in the study. The overall sample comprised T1-weighted MRI data from 482 individuals with EOP and 469 healthy controls. Each site performed the VBM analysis locally using the standardized ENIGMA-VBM tool. Statistical parametric T-maps were generated from each cohort and meta-analyzed to reveal voxel-wise differences between EOP and healthy controls as well as the individual-based association between GM volume and age of onset, chlorpromazine (CPZ) equivalent dose, and other clinical variables.
RESULTS: Compared with healthy controls, individuals with EOP showed widespread lower GM volume encompassing most of the cortex, with the most marked effect in the left median cingulate (Hedges' g = 0.55, p = 0.001 corrected), as well as small clusters of lower white matter (WM), whereas no regional GM or WM volumes were higher in EOP. Lower GM volume in the cerebellum, thalamus and left inferior parietal gyrus was associated with older age of onset. Deficits in GM in the left inferior frontal gyrus, right insula, right precentral gyrus and right superior frontal gyrus were also associated with higher CPZ equivalent doses.
CONCLUSION: EOP is associated with widespread reductions in cortical GM volume, while WM is affected to a smaller extent. GM volume alterations are associated with age of onset and CPZ equivalent dose but these effects are small compared to case-control differences. Mapping anatomical abnormalities in EOP may lead to a better understanding of the role of psychosis in brain development during childhood and adolescence
Crowdsourcing Methods for Data Collection in Geophysics: State of the Art, Issues, and Future Directions
Data are essential in all areas of geophysics. They are used to better understand and manage systems, either directly or via models. Given the complexity and spatiotemporal variability of geophysical systems (e.g., precipitation), a lack of sufficient data is a perennial problem, which is exacerbated by various drivers, such as climate change and urbanization. In recent years, crowdsourcing has become increasingly prominent as a means of supplementing data obtained from more traditional sources, particularly due to its relatively low implementation cost and ability to increase the spatial and/or temporal resolution of data significantly. Given the proliferation of different crowdsourcing methods in geophysics and the promise they have shown, it is timely to assess the state‐of‐the‐art in this field, to identify potential issues and map out a way forward. In this paper, crowdsourcing‐based data acquisition methods that have been used in seven domains of geophysics, including weather, precipitation, air pollution, geography, ecology, surface water and natural hazard management are discussed based on a review of 162 papers. In addition, a novel framework for categorizing these methods is introduced and applied to the methods used in the seven domains of geophysics considered in this review. This paper also features a review of 93 papers dealing with issues that are common to data acquisition methods in different domains of geophysics, including the management of crowdsourcing projects, data quality, data processing and data privacy. In each of these areas, the current status is discussed and challenges and future directions are outlined
Molecular imprinting science and technology: a survey of the literature for the years 2004-2011
Stabilisation of compliant floating platforms with sheet barriers under wave action
Excessive surface displacement of a compliant floating platform made of interconnected modular floats due to wave action can cause damage to the utility system (solar power, etc.) or endanger the safety of the service personnel on top. This study examines the use of a vertical tensioned sheet barrier installed in front of the floating platform for its stablisation under incident waves. Two configurations are investigated, namely finite and semi-infinite, representing a medium and large size platform respectively. Analytical analysis is performed without the pre-assumption of the dynamic behavior of the sheet barrier, and solutions are obtained using the eigenfunction expansion together with the least square method. For both configurations, the wave transmission to the floating platform reduces when the dynamic of the sheet barrier shifts from plate-like to membrane-like with increasing tension and also deeper draft and larger viscosity, which in turn reduces the platform displacement and the hydrodynamic pressure force on the platform. Overall, the results in the present study show that the installation of the barrier in front of the platform in the membrane-like hydroelastic regime with a penetration ratio more than ∼0.4 can significantly improve the stability of the compliant floating platform in the coastal environment.Submitted/Accepted versio
- …