Low-cost particulate matter (PM) sensors are promising
tools for supplementing existing air quality monitoring networks. However,
the performance of the new generation of low-cost PM sensors under ...field
conditions is not well understood. In this study, we characterized the
performance capabilities of a new low-cost PM sensor model (Plantower model
PMS3003) for measuring PM2.5 at 1 min, 1 h, 6 h, 12 h, and 24 h
integration times. We tested the PMS3003 sensors in both low-concentration suburban
regions (Durham and Research Triangle Park (RTP), NC, US) with 1 h
PM2.5 (mean ± SD) of 9±9 and 10±3 µg m−3, respectively, and a high-concentration urban
location (Kanpur, India) with 1 h PM2.5 of 36±17 and 116±57 µg m−3 during monsoon and post-monsoon
seasons, respectively. In Durham and Kanpur, the sensors were compared to a
research-grade instrument (environmental β attenuation monitor, E-BAM) to determine how these sensors perform across
a range of PM2.5 concentrations and meteorological factors (e.g., temperature and relative
humidity, RH). In RTP, the sensors were compared to three Federal
Equivalent Methods (FEMs) including two Teledyne model T640s and a
Thermo Scientific model 5030 SHARP to demonstrate the importance of the type
of reference monitor selected for sensor calibration. The decrease in 1 h
mean errors of the calibrated sensors using univariate linear models from
Durham (201 %) to Kanpur monsoon (46 %) and post-monsoon (35 %)
seasons showed that PMS3003 performance generally improved as ambient
PM2.5 increased. The precision of reference instruments (T640:
±0.5 µg m−3 for 1 h; SHARP: ±2 µg m−3 for
24 h, better than the E-BAM) is critical in evaluating sensor performance,
and β-attenuation-based monitors may not be ideal for testing PM
sensors at low concentrations, as underscored by (1) the less dramatic error
reduction over averaging times in RTP against optically based T640 (from 27 % for 1 h to 9 % for 24 h) than in Durham (from 201 % to 15 %);
(2) the lower errors in RTP than the Kanpur post-monsoon season (from 35 % to
11 %); and (3) the higher T640–PMS3003 correlations (R2≥0.63) than SHARP–PMS3003 (R2≥0.25). A major RH influence was
found in RTP (1 h RH =64±22 %) due to the relatively high
precision of the T640 measurements that can explain up to ∼30 % of the variance in 1 min to 6 h PMS3003 PM2.5 measurements. When
proper RH corrections are made by empirical nonlinear equations after using
a more precise reference method to calibrate the sensors, our work suggests
that the PMS3003 sensors can measure PM2.5 concentrations within
∼10 % of ambient values. We observed that PMS3003 sensors
appeared to exhibit a nonlinear response when ambient PM2.5 exceeded
∼125 µg m−3 and found that the quadratic fit is
more appropriate than the univariate linear model to capture this
nonlinearity and can further reduce errors by up to 11 %. Our results
have substantial implications for how variability in ambient PM2.5 concentrations, reference monitor types, and meteorological factors can
affect PMS3003 performance characterization.
Highlights • ELS perturbs microglial function during a critical period of brain development. • ELS impairs multiple developmental processes that are regulated by microglia. • ELS modifies the ...activity of key transcription factors in postnatal microglia. • ELS causes long-term changes in microglia function.
There is increasing interest in the role of physical exercise as a therapeutic strategy for individuals with Alzheimer's disease (AD). We assessed the effect of 26 weeks (6 months) of a supervised ...aerobic exercise program on memory, executive function, functional ability and depression in early AD.
This study was a 26-week randomized controlled trial comparing the effects of 150 minutes per week of aerobic exercise vs. non-aerobic stretching and toning control intervention in individuals with early AD. A total of 76 well-characterized older adults with probable AD (mean age 72.9 7.7) were enrolled and 68 participants completed the study. Exercise was conducted with supervision and monitoring by trained exercise specialists. Neuropsychological tests and surveys were conducted at baseline,13, and 26 weeks to assess memory and executive function composite scores, functional ability (Disability Assessment for Dementia), and depressive symptoms (Cornell Scale for Depression in Dementia). Cardiorespiratory fitness testing and brain MRI was performed at baseline and 26 weeks. Aerobic exercise was associated with a modest gain in functional ability (Disability Assessment for Dementia) compared to individuals in the ST group (X2 = 8.2, p = 0.02). There was no clear effect of intervention on other primary outcome measures of Memory, Executive Function, or depressive symptoms. However, secondary analyses revealed that change in cardiorespiratory fitness was positively correlated with change in memory performance and bilateral hippocampal volume.
Aerobic exercise in early AD is associated with benefits in functional ability. Exercise-related gains in cardiorespiratory fitness were associated with improved memory performance and reduced hippocampal atrophy, suggesting cardiorespiratory fitness gains may be important in driving brain benefits.
ClinicalTrials.gov NCT01128361.
ABSTRACT
The use of acoustic Doppler current profilers (ADCP) for discharge measurements and three‐dimensional flow mapping has increased rapidly in recent years and has been primarily driven by ...advances in acoustic technology and signal processing. Recent research has developed a variety of methods for processing data obtained from a range of ADCP deployments and this paper builds on this progress by describing new software for processing and visualizing ADCP data collected along transects in rivers or other bodies of water. The new utility, the Velocity Mapping Toolbox (VMT), allows rapid processing (vector rotation, projection, averaging and smoothing), visualization (planform and cross‐section vector and contouring), and analysis of a range of ADCP‐derived datasets. The paper documents the data processing routines in the toolbox and presents a set of diverse examples that demonstrate its capabilities. The toolbox is applicable to the analysis of ADCP data collected in a wide range of aquatic environments and is made available as open‐source code along with this publication. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Combined psychophysical and neurophysiological research has resulted in a relatively complete picture of the neural mechanisms of tactile perception. The results support the idea that each of the ...four mechanoreceptive afferent systems innervating the hand serves a distinctly different perceptual function, and that tactile perception can be understood as the sum of these functions. Furthermore, the receptors in each of those systems seem to be specialized for their assigned perceptual function.
Emerging infectious diseases in humans are frequently caused by pathogens originating from animal hosts, and zoonotic disease outbreaks present a major challenge to global health. To investigate ...drivers of virus spillover, we evaluated the number of viruses mammalian species have shared with humans. We discovered that the number of zoonotic viruses detected in mammalian species scales positively with global species abundance, suggesting that virus transmission risk has been highest from animal species that have increased in abundance and even expanded their range by adapting to human-dominated landscapes. Domesticated species, primates and bats were identified as having more zoonotic viruses than other species. Among threatened wildlife species, those with population reductions owing to exploitation and loss of habitat shared more viruses with humans. Exploitation of wildlife through hunting and trade facilitates close contact between wildlife and humans, and our findings provide further evidence that exploitation, as well as anthropogenic activities that have caused losses in wildlife habitat quality, have increased opportunities for animal-human interactions and facilitated zoonotic disease transmission. Our study provides new evidence for assessing spillover risk from mammalian species and highlights convergent processes whereby the causes of wildlife population declines have facilitated the transmission of animal viruses to humans.
Since
Amato and Gilbreth's (1999)
meta-analysis of nonresident father involvement and child well-being, nonmarital childbirths and nonresident father involvement both have increased. The unknown ...implications of such changes motivated the present study, a meta-analytic review of 52 studies of nonresident father involvement and child well-being. Consistent with Amato and Gilbreth, we found that positive forms of involvement were associated with benefits for children, with a small but statistically significant effect size. Amounts of father-child contact and financial provision, however, were not associated with child well-being. Going beyond Amato and Gilbreth, we analyzed the associations between different types of fathering and overall child well-being, and between overall father involvement and different types of child well-being. We found that nonresident father involvement was most strongly associated with children's social well-being and also was associated with children's emotional well-being, academic achievement, and behavioral adjustment. The forms of father involvement most strongly associated with child well-being were involvement in child-related activities, having positive father-child relationships, and engaging in multiple forms of involvement. Moderator analyses demonstrated variation in effect sizes based on both study characteristics and demographic variables. We discuss the implications of these findings for policy and practice.
The paper introduces a robust method to detect random errors and cyber-attacks targeting alternating current (AC) dynamic state estimation through false data injection. The dynamic state estimator ...uses measurements that are delivered at a high reporting rate from synchrophasors or phasor measurement units (PMUs). A statistical outlier detection algorithm using the S-estimator is implemented on successive batch-mode regression representations of the extended Kalman filter (EKF). The S-estimator is a robust regression estimator that resists the effect of outliers and bad measurements. Theoretically, an S-estimator offers an improved detection of outliers compared with other methods implemented in the smart grid literature such as the Huber M-estimator and the Generalized Huber M-estimator (GM-estimator). The S-estimator has the advantage of offering a high breakdown point and can resist both observation outliers and leverage points. The introduced S-based EKF accurately tracks the fast variations of states when the PMU data is either clean or contaminated by bad measurements and cyber attacks. The proposed filter also accurately tracks the states when errors and cyber attacks target the topology of the grid. The simulations are conducted on the IEEE 14-bus system.
Epidemiological studies suggest a dose-response relationship exists between physical activity and cognitive outcomes. However, no direct data from randomized trials exists to support these indirect ...observations. The purpose of this study was to explore the possible relationship of aerobic exercise dose on cognition. Underactive or sedentary participants without cognitive impairment were randomized to one of four groups: no-change control, 75, 150, and 225 minutes per week of moderate-intensity semi-supervised aerobic exercise for 26-weeks in a community setting. Cognitive outcomes were latent residual scores derived from a battery of 16 cognitive tests: Verbal Memory, Visuospatial Processing, Simple Attention, Set Maintenance and Shifting, and Reasoning. Other outcome measures were cardiorespiratory fitness (peak oxygen consumption) and measures of function functional health. In intent-to-treat (ITT) analyses (n = 101), cardiorespiratory fitness increased and perceived disability decreased in a dose-dependent manner across the 4 groups. No other exercise-related effects were observed in ITT analyses. Analyses restricted to individuals who exercised per-protocol (n = 77) demonstrated that Simple Attention improved equivalently across all exercise groups compared to controls and a dose-response relationship was present for Visuospatial Processing. A clear dose-response relationship exists between exercise and cardiorespiratory fitness. Cognitive benefits were apparent at low doses with possible increased benefits in visuospatial function at higher doses but only in those who adhered to the exercise protocol. An individual’s cardiorespiratory fitness response was a better predictor of cognitive gains than exercise dose (i.e., duration) and thus maximizing an individual’s cardiorespiratory fitness may be an important therapeutic target for achieving cognitive benefits.
ClinicalTrials.gov NCT01129115.
Attention and memory are typically studied as separate topics, but they are highly intertwined. Here we discuss the relation between memory and two fundamental types of attention: perceptual and ...reflective. Memory is the persisting consequence of cognitive activities initiated by and/or focused on external information from the environment (perceptual attention) and initiated by and/or focused on internal mental representations (reflective attention). We consider three key questions for advancing a cognitive neuroscience of attention and memory: To what extent do perception and reflection share representational areas? To what extent are the control processes that select, maintain, and manipulate perceptual and reflective information subserved by common areas and networks? During perception and reflection, to what extent are common areas responsible for binding features together to create complex, episodic memories and for reviving them later? Considering similarities and differences in perceptual and reflective attention helps integrate a broad range of findings and raises important unresolved issues.
PDF
