ICA model order selection of task co-activation networks

Independent component analysis (ICA) has become a widely used method for extracting functional networks in the brain during rest and task. Historically, preferred ICA dimensionality has widely varied within the neuroimaging community, but typically varies between 20 and 100 components. This can be problematic when comparing results across multiple studies because of the impact ICA dimensionality has on the topology of its resultant components. Recent studies have demonstrated that ICA can be applied to peak activation coordinates archived in a large neuroimaging database (i.e., BrainMap Database) to yield whole-brain task-based co-activation networks. A strength of applying ICA to BrainMap data is that the vast amount of metadata in BrainMap can be used to quantitatively assess tasks and cognitive processes contributing to each component. In this study, we investigated the effect of model order on the distribution of functional properties across networks as a method for identifying the most informative decompositions of BrainMap-based ICA components. Our findings suggest dimensionality of 20 for low model order ICA to examine large-scale brain networks, and dimensionality of 70 to provide insight into how large-scale networks fractionate into sub-networks. We also provide a functional and organizational assessment of visual, motor, emotion, and interoceptive task co-activation networks as they fractionate from low to high model-orders

PTF11kx: A Type Ia Supernova with Hydrogen Emission Persisting After 3.5 Years

The optical transient PTF11kx exhibited both the characteristic spectral features of Type Ia supernovae (SNe Ia) and the signature of ejecta interacting with circumstellar material (CSM) containing hydrogen, indicating the presence of a nondegenerate companion. We present an optical spectrum at $1342$ days after peak from Keck Observatory, in which the broad component of H$\alpha$ emission persists with a similar profile as in early-time observations. We also present $Spitzer$ IRAC detections obtained $1237$ and $1818$ days after peak, and an upper limit from $HST$ ultraviolet imaging at $2133$ days. We interpret our late-time observations in context with published results - and reinterpret the early-time observations - in order to constrain the CSM's physical parameters and compare to theoretical predictions for recurrent nova systems. We find that the CSM's radial extent may be several times the distance between the star and the CSM's inner edge, and that the CSM column density may be two orders of magnitude lower than previous estimates. We show that the H$\alpha$ luminosity decline is similar to other SNe with CSM interaction, and demonstrate how our infrared photometry is evidence for newly formed, collisionally heated dust. We create a model for PTF11kx's late-time CSM interaction and find that X-ray reprocessing by photoionization and recombination cannot reproduce the observed H$\alpha$ luminosity, suggesting that the X-rays are thermalized and that H$\alpha$ radiates from collisional excitation. Finally, we discuss the implications of our results regarding the progenitor scenario and the geometric properties of the CSM for the PTF11kx system.Comment: 15 pages, 8 figures, 3 tables; submitted to Ap

Carbon Sequestration by Reforesting Legacy Grasslands on Coal Mining Sites

Future carbon management during energy production will rely on carbon capture and sequestration technology and carbon sequestration methods for offsetting non-capturable losses. The present study quantifies carbon sequestration via reforestation using measurements and modeling for recent and legacy surface coal mining grasslands that are re-restored through tree planting. This paper focuses on a case study of legacy coal mining sites in the southern Appalachia the United States. This five million-hectare region has a surface mining footprint of approximately 12% of the land area, and the reclamation method was primarily grassland. The results of the soil carbon sequestration rates for restored forest soils approach 2.0 MgC ha−1 y−1 initially and average 1.0 MgC ha−1 y−1 for the first fifty years after reclamation. Plant, coarse root and litter carbon sequestration rates were 2.8 MgC ha−1 y−1 with plant carbon estimated to equilibrate to 110 MgC ha−1 after forty years. Plant, root and litter carbon stocks are projected to equilibrate at an order of magnitude greater carbon storage than the existing conditions, highlighting the net carbon gain. Reforestation of legacy mine sites shows carbon sequestration potential several orders of magnitude greater than typical land sequestration strategies for carbon offsets. Projections of future scenarios provide results that show the study region could be carbon neutral or a small sink if widespread reforesting during reclamation was implemented, which is contrary to the business-as-usual projections that result in a large amount of carbon being released to the atmosphere in this region

Solid State Proton Spin Relaxation and \u3ci\u3et\u3c/i\u3e-Butyl and Methyl Group Reorientation in 1-Bromo-2,4,6-Tri-\u3ci\u3et\u3c/i\u3e-Butylbenzene

We have used the solid state proton spin relaxation technique to investigate the barriers for methyl and t-butyl group reorientation in polycrystalline 1-bromo-2,4,6-tri-t-butylbenzene. The barriers in the range of 15-19 kJ/mol (3-5 kcal/mol) are compared with those found in related molecules. It is shown that the neighboring ring bromine atom has an effect on the barrier for t-butyl group reorientation similar to that of a neighboring hydrogen atom despite the significantly larger van der Waals\u27 radius of a bromine atom. This most likely occurs because of the relatively long carbon-bromine bond, the distorted ring geometry, and the relatively high polarizability of bromine. In addition, the barriers for methyl group reorientation, about 16 kJ/mol, seem to be largely intra-t-butyl in origin

Solid State Proton Spin Relaxation and \u3ci\u3et\u3c/i\u3e-Butyl and Methyl Group Reorientation in 1-Bromo-2,4,6-Tri-\u3ci\u3et\u3c/i\u3e-Butylbenzene

We have used the solid state proton spin relaxation technique to investigate the barriers for methyl and t-butyl group reorientation in polycrystalline 1-bromo-2,4,6-tri-t-butylbenzene. The barriers in the range of 15-19 kJ/mol (3-5 kcal/mol) are compared with those found in related molecules. It is shown that the neighboring ring bromine atom has an effect on the barrier for t-butyl group reorientation similar to that of a neighboring hydrogen atom despite the significantly larger van der Waals\u27 radius of a bromine atom. This most likely occurs because of the relatively long carbon-bromine bond, the distorted ring geometry, and the relatively high polarizability of bromine. In addition, the barriers for methyl group reorientation, about 16 kJ/mol, seem to be largely intra-t-butyl in origin

A cost-effective fluorescence detection system for pulsed laser analysis

A cost-effective fluorescence detection system has been developed using a National Instruments PCI-6251 data acquisition (DAQ) board that is driven by LabVIEW Signal Express. The signal is collected using a collimator and transported to the DAQ board using a fiber-coupled detector. The same detection system has been incorporated into an inverted microscope fitted with internal dichroic mirrors to provide a cost-effective alternative to commercial fluorescence microscopes. The detection system has been used to measure fluorescence intensity and generate a laser power curve that can be used for pulsed lasers. Different data analysis approaches have been compared and standard deviation and signal-to-noise ratios have been determined

Plasma Leptin Levels and Incidence of Heart Failure, Cardiovascular Disease, and Total Mortality in Elderly Individuals

OBJECTIVE: Obesity predisposes individuals to congestive heart failure (CHF) and cardiovascular disease (CVD). Leptin regulates energy homeostasis, is elevated in obesity, and influences ventricular and vascular remodeling. We tested the hypothesis that leptin levels are associated with greater risk of CHF, CVD, and mortality in elderly individuals. RESEARCH DESIGN AND METHODS: We evaluated 818 elderly (mean age 79 years, 62% women) Framingham Study participants attending a routine examination at which plasma leptin was assayed. RESULTS: Leptin levels were higher in women and strongly correlated with BMI (P < 0.0001). On follow-up (mean 8.0 years), 129 (of 775 free of CHF) participants developed CHF, 187 (of 532 free of CVD) experienced a first CVD event, and 391 individuals died. In multivariable Cox regression models adjusting for established risk factors, log-leptin was positively associated with incidence of CHF and CVD (hazard ratio [HR] per SD increment 1.26 [95% CI 1.03–1.55] and 1.28 [1.09–1.50], respectively). Additional adjustment for BMI nullified the association with CHF (0.97 [0.75–1.24]) but only modestly attenuated the relation to CVD incidence (1.23 [1.00–1.51], P = 0.052). We observed a nonlinear, U-shaped relation between log-leptin and mortality (P = 0.005 for quadratic term) with greater risk of death evident at both low and high leptin levels. CONCLUSIONS: In our moderate-sized community-based elderly sample, higher circulating leptin levels were associated with a greater risk of CHF and CVD, but leptin did not provide incremental prognostic information beyond BMI. Additional investigations are warranted to elucidate the U-shaped relation of leptin to mortality.National Institutes of Health's National Heart, Lung, and Blood Institute (N01-HC25195, N01-HV28178, K24-HL04334, R01-DK080739

Undiagnosed dementia in primary care: A record linkage study

BackgroundThe number of people living with dementia is greater than the number with a diagnosis of dementia recorded in primary care. This suggests that a significant number are living with dementia that is undiagnosed. Little is known about this group and there is little quantitative evidence regarding the consequences of diagnosis for people with dementia.ObjectivesThe aims of this study were to (1) describe the population meeting the criteria for dementia but without diagnosis, (2) identify predictors of being diagnosed and (3) estimate the effect of diagnosis on mortality, move to residential care, social participation and well-being.DesignA record linkage study of a subsample of participants (n = 598) from the Cognitive Function and Ageing Study II (CFAS II) (n = 7796), an existing cohort study of the population of England aged ≥ 65 years, with standardised validated assessment of dementia and consent to access medical records.Data sourcesData on dementia diagnoses from each participant’s primary care record and covariate and outcome data from CFAS II.SettingA population-representative cohort of people aged ≥ 65 years from three regions of England between 2008 and 2011.ParticipantsA total of 598 CFAS II participants, which included all those with dementia who consented to medical record linkage (n = 449) and a stratified sample without dementia (n = 149).Main outcome measuresThe main outcome was presence of a diagnosis of dementia in each participant’s primary care record at the time of their CFAS II assessment(s). Other outcomes were date of death, cognitive performance scores, move to residential care, hospital stays and social participation.ResultsAmong people with dementia, the proportion with a diagnosis in primary care was 34% in 2008–11 and 44% in 2011–13. In both periods, a further 21% had a record of a concern or a referral but no diagnosis. The likelihood of having a recorded diagnosis increased with severity of impairment in memory and orientation, but not with other cognitive impairment. In multivariable analysis, those aged ≥ 90 years and those age

Retinotopic organization of human visual cortex mapped with positron-emission tomography

The retinotopic organization of primary visual cortex was mapped in normal human volunteers. Positron-emission tomographic measurements of regional cerebral blood flow were employed to detect focal functional brain activation. Oxygen-15-labeled water, delivered by intravenous bolus, was used as the blood flow tracer to allow multiple stimulated- state (n = 5) and control-state (n = 3) measurements to be acquired for each of 7 subjects. Responses were identified by applying a maximum- detection algorithm to subtraction-format images of the stimulus- induced change in cerebral blood flow. Response locales were described using a standardized system of stereotactic coordinates. Changes in stimulus location (macular, perimacular, peripheral, upper-field, lower- field) caused systematic, highly significant changes in response locale within visual cortex. Discrete extrastriate visual responses were also observed