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Firefighters are routinely exposed to various traumatic events and often experience a range of trauma-related symptoms. Although these repeated traumatic exposures rarely progress to the development of post-traumatic stress disorder, firefighters are still considered to be a vulnerable population with regard to trauma.
To investigate how the human brain responds to or compensates for the repeated experience of traumatic stress.
We included 98 healthy firefighters with repeated traumatic experiences but without any diagnosis of mental illness and 98 non-firefighter healthy individuals without any history of trauma. Functional connectivity within the fear circuitry, which consists of the dorsal anterior cingulate cortex, insula, amygdala, hippocampus and ventromedial prefrontal cortex (vmPFC), was examined using resting-state functional magnetic resonance imaging. Trauma-related symptoms were evaluated using the Impact of Event Scale – Revised.
The firefighter group had greater functional connectivity between the insula and several regions of the fear circuitry including the bilateral amygdalae, bilateral hippocampi and vmPFC as compared with healthy individuals. In the firefighter group, stronger insula–amygdala connectivity was associated with greater severity of trauma-related symptoms (β = 0.36, P = 0.005), whereas higher insula–vmPFC connectivity was related to milder symptoms in response to repeated trauma (β = −0.28, P = 0.01).
The current findings suggest an active involvement of insular functional connectivity in response to repeated traumatic stress. Functional connectivity of the insula in relation to the amygdala and vmPFC may be potential pathways that underlie the risk for and resilience to repeated traumatic stress, respectively.
We demonstrate the tungsten disulfide (WS2) thin film catalysts prepared by the sulfurization of vacuum deposited WO3 thin films for efficient hydrogen production with over 90% Faradaic efficiency. The 23-nm-thick WS2 thin film catalyst heterojunction with p-type silicon photocathode could exhibit a photocurrent density of 8.3 mA/cm2 at 0 V versus a reversible hydrogen electrode (RHE), a low onset potential of 0.2 V versus RHE when photocurrent density reaches −1 mA/cm2 and long-term stability over 10 h. The enhanced catalytic activities of WS2/p-Si photocathodes compared with the bare p-Si photocathode originate from a number of edge sites in the synthesized polycrystalline thin films, which could act as hydrogen evolution catalyst.
Cerebral white matter hyperintensities (WMH) are prevalent incident findings on brain MRI scans among elderly people and have been consistently implicated in cognitive dysfunction. However, differential roles of WMH by region in cognitive function are still unclear. The aim of this study was to ascertain the differential role of regional WMH in predicting progression from mild cognitive impairment (MCI) to different subtypes of dementia.
Participants were recruited from the Clinical Research Center for Dementia of South Korea (CREDOS) study. A total of 622 participants with MCI diagnoses at baseline and follow-up evaluations were included for the analysis. Initial MRI scans were rated for WMH on a visual rating scale developed for the CREDOS. Differential effects of regional WMH in predicting incident dementia were evaluated using the Cox proportional hazards model.
Of the 622 participants with MCI at baseline, 139 patients (22.3%) converted to all-cause dementia over a median of 14.3 (range 6.0–36.5) months. Severe periventricular WMH (PWMH) predicted incident all-cause dementia (Hazard ratio (HR) 2.22; 95% confidence interval (CI) 1.43–3.43) and Alzheimer's disease (AD) (HR 1.86; 95% CI 1.12–3.07). Subcortical vascular dementia (SVD) was predicted by both PWMH (HR 16.14; 95% CI 1.97–132.06) and DWMH (HR 8.77; 95% CI 1.77–43.49) in more severe form (≥ 10 mm).
WMH differentially predict dementia by region and severity. Our findings suggest that PWMH may play an independent role in the pathogenesis of dementia, especially in AD.
Cultivated soybeans [Glycinemax (L.) Merr.] have various flower colours such as dark purple, purple, light purple, pink, magenta, near white and white. About one-third of the soybean accessions in the United States Department of Agriculture – Germplasm Resource Information Network (USDA-GRIN) Soybean Germplasm Collections have white flowers and are the second dominant accessions after the purple-flowered accessions. Earlier studies have shown that the w1 recessive allele of the W1 gene encoding flavonoid 3′,5′-hydroxylase produces white flowers. In the present study, we aimed to understand why the white-flowered accessions have become abundant among the cultivated soybeans and what their genetic and regional origin is. For this purpose, 99 landraces with white flowers and 39 landraces with purple flowers from eight Asian countries and Russia were analysed with regard to the nucleotide sequences of the W1 locus. We not only found that the w1 alleles of the 99 white-flowered landraces were identical to those of the white-flowered Williams 82, but also found that these w1 alleles displayed no polymorphism at all. By carrying out a phylogenetic analysis, we were able to identify a group with W1 alleles from which the w1 allele might have diverged.
Whether an association exists between cerebral microbleeds (CMBs) and functional recovery after ischemic stroke is unclear. We aimed to evaluate the association between CMBs and functional outcome after acute ischemic stroke.
Consecutive patients with acute stroke were enrolled, and all patients were stratified into good and poor functional outcome groups at discharge and 6 months after ischemic stroke by using a modified Rankin Scale score. Cardiovascular risk factors, CMBs, and white matter hyperintensities were compared between these two outcome groups. Logistic regression analysis was used to estimate the risk of poor functional outcomes.
A total of 225 patients were enrolled, 121 of whom were classified as having a good functional outcome at discharge and 142 as having a good 6-month functional outcome. The presence of CMBs was associated with a poor functional outcome at discharge [CMBs (+) patients in poor vs. good functional group; 48.1% vs. 30.6%; p=0.007] and 6 months [53.0% vs. 30.3%; p=0.001]. After adjustment for confounding factors, only the presence of infratentorial CMBs was associated with a poor functional outcome at discharge and 6 months. The poor functional outcome group had more CMBs than the good outcome group at 6 months.
Infratentorial cerebral microbleeds were significantly associated with worse functional outcomes not only in the early phase of ischemic stroke but also in the chronic phase. These findings suggest that the presence of infratentorial CMBs can predict poor functional outcome after acute ischemic stroke.
A 44-year-old man developed sudden non-fluent aphasia and right hemiplegia due to left striatocapsular infarction (Figure). Neurologic examination revealed gaze deviation to the right with eyes closed, but not with eyes open (Video). There was no spontaneous or gaze-evoked nystagmus, even after elimination of visual fixation. Leftward pursuit was impaired in a craniotopic frame of reference, and horizontal saccades were hypometric in both directions. Head impulse test was normal in the horizontal plane and there were no visual field defects. The contralesional gaze deviation with eye closure persisted for ten days.
The prevalence of the feeling of cold hands and feet (FCHF) is high in the
general population but the etiology of FCHF is largely unknown. The aim of the
present study was to explore whether the FCHF is heritable. Eight hundred and
ninety-four pairs of twins completed a question about FCHF. Tetrachoric
correlations for FCHF were .58, .29, .67, .52, and .04 for monozygotic male,
dizygotic male, monozygotic female, and dizygotic female twins, respectively.
Model-fitting analyses suggested that in the best fitting model, additive
genetic and nonshared environmental variance including measurement error were
64% (95% CI: 55%-72%) and 36% (28%-45%), respectively. Sex differences in
genetic and environmental influences were not significant.
Despite numerous previous studies, relationships between watershed land use and adjacent streams and rivers at various scales in Korea remain unclear. This study investigated the relationships between land uses and the physical, chemical, and biological characteristics of 720 sites of streams and rivers across the country. The land uses at two spatial scales, including a 1-km buffer and the base watershed management region (BWMR), were computed in a geographical information system (GIS) with a digital land use/land cover map. Characteristics of land uses at two spatial scales were then correlated with the monitored multidimensional characteristics of the streams and rivers. The results of this study indicate that land use types have significant effects on stream and river characteristics. Specifically, most characteristics were negatively correlated with the proportions of urban, rice paddy, agricultural, and bare soil areas and positively correlated with the amount of forest. The site-scale and BWMR-scale analyses suggest that BWMR land use patterns were more strongly related to ecological integrity than they were to site land use patterns. Improving our understanding of land use effects will largely depend on relating the results of site-specific studies that use similar response techniques and measures to evaluate ecological integrity. In addition, our results clearly indicate that the characteristics of streams and rivers are closely linked and that land use types differentially affect those characteristics. Thus, effective restoration and management for ecological integrity of lotic system should consider the physical, chemical, and biological factors in combination.
In this study, we synthesized ZnO nanowires using Au catalytic particles formed on a ZnO seed layer. We modulated the microstructure of the ZnO seed layer by changing the sputtering power to investigate how the underlying ZnO film microstructure affects the distribution of ZnO nanowires. Examining the samples after each of the three key steps of the growth process (ZnO seed layer deposition, Au catalytic particle formation, and nanowire growth) using various characterization methods such as scanning electron microscopy, transmission electron microscopy, and x-ray diffraction helped us illuminate the profound impacts of the grain size of the seed layer on the nanowire density.
YMnO3 thin films were sputtered on Si (100) substrates under different ambient conditions. After rapid thermal annealing process at 850 °C, the YMnO3 film deposited in Ar ambient had random orientations and the YMnO3 film deposited in Ar+O2 ambient was crystallized with distinct two layers, i.e., c-axis oriented layer in top region and random oriented layer in bottom region. Relations between the microstructure and the electrical properties of Pt/YMnO3/Si capacitor were investigated. Memory window and leakage current depended on the orientation of the YMnO3 thin films and the interfacial microstructure of the YMnO3/Si, respectively
Two kinds of nanocrystalline Tin doped indium oxide (or indium tin oxide: denoted ITO hereafter) powders with different crystal structures – rhombohedral and cubic – were prepared using a coprecipitation method through the control of pH of a mixing solution and aging time after coprecipitation. The two powders have the same particle size of 15 nm in diameter but different morphologies (spherical for rhomboheral and rectangular for cubic). The gaseous ethanol sensing characteristics of the sensors prepared by the two ITO powders were quite different. The sensitivity of rhombohedral ITO sensor was high compared to that of the cubic ITO sensor across all temperatures. The reason for this is explained through the viewpoint of the binding energy of XPS and the surface structure relating to the crystal structure.
Field emission characteristics were investigated for zinc oxide nanostructures which were grown on NiO catalyzed silicon (100) substrate by chemical vapor deposition method. The asgrown zinc oxide showed needle-shaped nanostructures with tip diameters of 20∼40 nm and length of 3∼5 νm. The turn-on field was found to be about 6 V/νm at a current density of 1 νA/cm2. After several field emission measurements, the turn-on field was increased up to 8.5 V/νm and the magnitude of field enhancement factor was decreased from 1190 to 940. According to SEM, the tip diameter increase of the zinc oxide to 60 nm was observed after several emission measurements. Therefore, degradation of the field emission characteristic after measurements is attributed to this deformation of the tip shape.
Self-aligned silicide (salicide) formation of epitaxial CoSi2, using a Co/Ti bilayer, on linear oxide (SiO2) patterned (100)Si substrate has been investigated. Rapid thermal annealing (RTA) at 550°C resulted in the lateral encroachment of silicide in the Si under the edge of the oxide. After RTA at 900°C, even though an epitaxial CoSi2 layer was formed on the Si substrate, defects such as lateral encroachment and voids were generated under the edge of the oxide. It was found that such defects lead to device failure due to the deterioration of the gate oxide and the shallow junction.
Perovskite La1-xCaxMnO3-δ (LCMO) thin films with a wide range of x, i.e., 0.0 ≤ x ≤ 0.6, were deposited on MgO(001) substrates using a pulsed laser deposition (PLD) technique. Epitaxial La0.7Ca0.3MnO3-δ/MgO thin films were able to be grown under a condition such as 1.5 ∼ 2.1 J/cm2 of a laser fluence, 650 ∼ 750 °C of a substrate temperature, and 100 ∼ 300 mtorr of an oxygen pressure. X-ray pole figures and electron diffraction pattern showed that the LCMO films were grown epitaxially on MgO(001). Rutherford Backscattering Spectroscopy measurements investigated that the epitaxial LCMO films have compositions similar to those of targets, demonstrating the PLD is a useful technique to get films with complicated chemical compositions. Various physical properties, including resistance, R, magnetoresistance, ΔR/R(H=0) ≡ (R(H)-R(0))/R(O), and magnetization, M(T), were measured. The LCMO thin films with 0.2 ≤ x ≤ 0.5 had both semiconductor-metal and ferromagnetic ordering transitions, whose temperatures are located close to each other. These physical properties were explained in terms of the magnetic polaron model.
Field emissions from the singlewalled carbon nanotubes (SWNTs) attached on various patterned substrates such as silicon wafer and polymer film, are reported. SWNTs were cut into sub-micron length by sonication in an acidic solution. The SWNT emitters were aligned on Au surface at room temperature by self-assembly monolayer technique. The field emission measurements in a silicon wafer and a polymer film showed that the turn-on fields were 2.8 V/ νm and 3.9 V/ νm at the emission current density of 10 μA/cm2, respectively. The current densities were 0.9 mA/cm2 and 1.6 mA/cm2 at 6.0 V/ νm. This room temperature process is suitable for the fabrication of flexible field emission devices with carbon nanotubes.
Microstructures and interdiffusions of Pt/Ti/SiO2/Si and RuO2/SiO2/Si during annealing in O2 were investigated using x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The degree of oxidation and the interdiffusion of elements have remarkably increased with increasing temperature above 500 °C for the Pt/Ti/SiO2/Si case. The generation of Pt hillocks commenced at 500 °C. The Pt-silicide phase was also observed near the TiOx/SiO2 interface. The microstructural variations occurred to only a small amount for the RuO2/SiO2/Si case over the temperature range 300 – 700 °C. While there was no hillock formation, the RuO2 film surface was roughened by the thermal grooving phenomenon. A thin interlayer phase was found at the RuO2/SiO2 interface.
The cross-sectional transmission electron microscopy (TEM) specimens of Pt/Ti/SiO2/Si, RuO2/SiO2/Si, W/TiN/SiO2/Si, (Pb,La)TiO3/Pt/MgO, Bi4Ti3O12/Lal-xCaxMnO3/MgO, and GaN/Al2O3 were successfully made by the rocking-angle ion-milling technique. The differential thinning problems could be effectively mitigated when the rocking-angle and the ion-beam incidence angle were optimized for each heterostructure. It was found that the sputtering yield ratio between the layer milled most quickly and the layer milled most slowly is one of the important factors which determine the optimum rocking-angle ion-milling condition. The atomic force microscopy study on the surface topography of the cross-sectional Pt/Ti/SiO2/Si TEM sample after ion-milling provided quantitative information about the effects of the rocking-angle variation. A parameter which is the ratio between the layer with a minimum electron transparency and the layer with a maximum electron transparency was suggested.
Using a gas mixture of propyne (C3H4) and ammonia (NH3) as a carbon precursor, we have successfully synthesized multiwalled carbon nanotubes (CNTs) by the direct current (dc) plasma enhanced chemical vapor deposition (PECVD) onto Co-sputtered glass at 550°C. As the flow ratio of NH3 to C3H4 in the mixture gas increased, the crystallinity and alignment of CNTs were improved. In addition, the field emission characteristics of CNTs were also improved. the turn-on voltage became lower, and the current density and the field enhancement factor were more increasing. Raman spectroscopy and scanning electron microscopy were utilized to confirm the effect of the gas flow ratio on CNTs. Therefore, the gas flow ratio was found to be one of important factors to govern the crystalline and field emission characteristics of CNTs. The growth mechanism of CNTs using a C3H4 gas is under investigation with the possibility that three carbon atoms in a C3H4 molecule is converted directly to a hexagon of a CNT by combining two molecules.