1,723 research outputs found
A decadal satellite record of gravity wave activity in the lower stratosphere to study polar stratospheric cloud formation
Atmospheric gravity waves yield substantial small-scale temperature fluctuations that can trigger the formation of polar stratospheric clouds (PSCs). This paper introduces a new satellite record of gravity wave activity in the polar lower stratosphere to investigate this process. The record is comprised of observations of the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite from January 2003 to December 2012. Gravity wave activity is measured in terms of detrended and noise-corrected 15 µm brightness temperature variances, which are calculated from AIRS channels that are the most sensitive to temperature fluctuations at about 17–32 km of altitude. The analysis of temporal patterns in the data set revealed a strong seasonal cycle in wave activity with wintertime maxima at mid- and high latitudes. The analysis of spatial patterns indicated that orography as well as jet and storm sources are the main causes of the observed waves. Wave activity is closely correlated with 30 hPa zonal winds, which is attributed to the AIRS observational filter. We used the new data set to evaluate explicitly resolved temperature fluctuations due to gravity waves in the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. It was found that the analysis reproduces orographic and non-orographic wave patterns in the right places, but that wave amplitudes are typically underestimated by a factor of 2–3. Furthermore, in a first survey of joint AIRS and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite observations, nearly 50 gravity-wave-induced PSC formation events were identified. The survey shows that the new AIRS data set can help to better identify such events and more generally highlights the importance of the process for polar ozone chemistry
Electrical Stimulation Modulates High γ Activity and Human Memory Performance.
Direct electrical stimulation of the brain has emerged as a powerful treatment for multiple neurological diseases, and as a potential technique to enhance human cognition. Despite its application in a range of brain disorders, it remains unclear how stimulation of discrete brain areas affects memory performance and the underlying electrophysiological activities. Here, we investigated the effect of direct electrical stimulation in four brain regions known to support declarative memory: hippocampus (HP), parahippocampal region (PH) neocortex, prefrontal cortex (PF), and lateral temporal cortex (TC). Intracranial EEG recordings with stimulation were collected from 22 patients during performance of verbal memory tasks. We found that high γ (62-118 Hz) activity induced by word presentation was modulated by electrical stimulation. This modulatory effect was greatest for trials with poor memory encoding. The high γ modulation correlated with the behavioral effect of stimulation in a given brain region: it was negative, i.e., the induced high γ activity was decreased, in the regions where stimulation decreased memory performance, and positive in the lateral TC where memory enhancement was observed. Our results suggest that the effect of electrical stimulation on high γ activity induced by word presentation may be a useful biomarker for mapping memory networks and guiding therapeutic brain stimulation
Gendered academic adjustment among Asian American adolescents in an emerging immigrant community
Abstract: Research on the academic adjustment of immigrant adolescents has been predominately conducted in large cities among established migration areas. To broaden the field's restricted focus, data from 172 (58% female) Asian American adolescents who reside within a nontraditional or emerging immigrant community in the Southeastern US were used to examine gender differences in academic adjustment as well as school, family, and cultural variables as potential mediators of gender differences found. Results suggest that girls report significantly higher educational goals, intrinsic academic motivation, and utility value of school compared to boys. These gender differences are statistically mediated by ethnic exploration and family processes, most prominently, family respect. School connectedness and perceived discrimination are also associated with academic adjustment at the bivariate level, suggesting that academic success may be best promoted if multiple domains of influence can be targeted. gender | academic adjustment | Asian adolescents | immigrants | immigran
Cross-correlating Carbon Monoxide Line-intensity Maps with Spectroscopic and Photometric Galaxy Surveys
Line-intensity mapping (LIM or IM) is an emerging field of observational
work, with strong potential to fit into a larger effort to probe large-scale
structure and small-scale astrophysical phenomena using multiple complementary
tracers. Taking full advantage of such complementarity means, in part,
undertaking line-intensity surveys with galaxy surveys in mind. We consider the
potential for detection of a cross-correlation signal between COMAP and blind
surveys based on photometric redshifts (as in COSMOS) or based on spectroscopic
data (as with the HETDEX survey of Lyman- emitters). We find that
obtaining accuracy in redshifts and
sources per Mpc with spectroscopic redshift determination
should enable a CO-galaxy cross spectrum detection significance at least twice
that of the CO auto spectrum. Either a future targeted spectroscopic survey or
a blind survey like HETDEX may be able to meet both of these requirements.Comment: 19 pages + appendix (31 pages total), 16 figures, 6 tables; accepted
for publication in Ap
Room-Temperature Distance Measurements of Immobilized Spin-Labeled Protein by DEER/PELDOR
Nitroxide spin labels are used for double electron-electron
resonance (DEER) measurements of distances between sites in
biomolecules. Rotation of gem-dimethyls in commonly used
nitroxides causes spin echo dephasing times (Tm) to be too
short to perform DEER measurements at temperatures between
∼80 and 295 K, even in immobilized samples. A spirocyclohexyl
spin label has been prepared that has longer Tm between 80
and 295 K in immobilized samples than conventional labels. Two
of the spirocyclohexyl labels were attached to sites on T4 lysozyme introduced by site-directed spin labeling. Interspin
distances up to ∼4 nm were measured by DEER at
temperatures up to 160 K in water/glycerol glasses. In a glassy
trehalose matrix the Tm for the doubly labeled T4 lysozyme was
long enough to measure an interspin distance of 3.2 nm at 295
K, which could not be measured for the same protein labeled
with the conventional 1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-
(methyl)methanethio-sulfonate label
Room-Temperature Distance Measurements of Immobilized Spin-Labeled Protein by DEER/PELDOR
Nitroxide spin labels are used for double electron-electron
resonance (DEER) measurements of distances between sites in
biomolecules. Rotation of gem-dimethyls in commonly used
nitroxides causes spin echo dephasing times (Tm) to be too
short to perform DEER measurements at temperatures between
∼80 and 295 K, even in immobilized samples. A spirocyclohexyl
spin label has been prepared that has longer Tm between 80
and 295 K in immobilized samples than conventional labels. Two
of the spirocyclohexyl labels were attached to sites on T4 lysozyme introduced by site-directed spin labeling. Interspin
distances up to ∼4 nm were measured by DEER at
temperatures up to 160 K in water/glycerol glasses. In a glassy
trehalose matrix the Tm for the doubly labeled T4 lysozyme was
long enough to measure an interspin distance of 3.2 nm at 295
K, which could not be measured for the same protein labeled
with the conventional 1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-
(methyl)methanethio-sulfonate label
The handedness-associated PCSK6 locus spans an intronic promoter regulating novel transcripts
We recently reported the association of the PCSK6 gene with handedness through a quantitative genome-wide association study (GWAS; P < 0.5 × 10(-8)) for a relative hand skill measure in individuals with dyslexia. PCSK6 activates Nodal, a morphogen involved in regulating left-right body axis determination. Therefore, the GWAS data suggest that the biology underlying the patterning of structural asymmetries may also contribute to behavioural laterality, e.g. handedness. The association is further supported by an independent study reporting a variable number tandem repeat (VNTR) within the same PCSK6 locus to be associated with degree of handedness in a general population cohort. Here, we have conducted a functional analysis of the PCSK6 locus combining further genetic analysis, in silico predictions and molecular assays. We have shown that the previous GWAS signal was not tagging a VNTR effect, suggesting that the two markers have independent effects. We demonstrated experimentally that one of the top GWAS-associated markers, rs11855145, directly alters the binding site for a nuclear factor. Furthermore, we have shown that the predicted regulatory region adjacent to rs11855415 acts as a bidirectional promoter controlling the expression of novel RNA transcripts. These include both an antisense long non-coding RNA (lncRNA) and a short PCSK6 isoform predicted to be coding. This is the first molecular characterization of a handedness-associated locus that supports the role of common variants in non-coding sequences in influencing complex phenotypes through gene expression regulation
Associations between neuropsychiatric and health status outcomes in individuals with probable mTBI
Mild traumatic brain injury (mTBI) is a common occurrence, and may impact distal outcomes in a subgroup of individuals. Improved characterization of health outcomes and identification of factors associated with poor outcomes is needed to better understand the impact of mTBI, particularly in those with co-occurring posttraumatic stress disorder (PTSD). Participants in a data repository of the Injury and Traumatic Stress (INTRuST) Clinical Consortium (n = 625) completed functional disability [FD] and health-related quality of life [HRQOL] questionnaires, and a subset completed a neuropsychological assessment. FD and HRQOL were compared among participants with probable mTBI (mTBI), probable mTBI with PTSD (mTBI/PTSD), and health comparison participants (HC). Associations between symptoms, neuropsychological performance, and health outcomes were examined in those with probable mTBI with and without PTSD (n = 316). Individuals in the mTBI/PTSD group endorsed poorer health outcomes than those in the mTBI group, who endorsed poorer outcomes than those in the HC group. Individuals in either mTBI group performed worse than those in the HC on verbal learning and memory and psychomotor speed. Health outcomes were correlated with mental health and postconcussive symptoms, as well as neuropsychological variables. mTBI may adversely impact self-reported health, with the greatest effect observed in individuals with co-occurring mTBI/PTSD
- …