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Generalized anxiety disorder (GAD) and social anxiety disorder (SAD) are co-morbid and associated with similar neural disruptions during emotion regulation. In contrast, the lack of optimism examined here may be specific to GAD and could prove an important biomarker for that disorder.
Unmedicated individuals with GAD (n = 18) and age-, intelligence quotient- and gender-matched SAD (n = 18) and healthy (n = 18) comparison individuals were scanned while contemplating likelihoods of high- and low-impact negative (e.g. heart attack; heartburn) or positive (e.g. winning lottery; hug) events occurring to themselves in the future.
As expected, healthy subjects showed significant optimistic bias (OB); they considered themselves significantly less likely to experience future negative but significantly more likely to experience future positive events relative to others (p < 0.001). This was also seen in SAD, albeit at trend level for positive events (p < 0.001 and p < 0.10, respectively). However, GAD patients showed no OB for positive events (t17 = 0.82, n.s.) and showed significantly reduced neural modulation relative to the two other groups of regions including the medial prefrontal cortex (mPFC) and caudate to these events (p < 0.001 for all). The GAD group further differed from the other groups by showing increased neural responses to low-impact events in regions including the rostral mPFC (p < 0.05 for both).
The neural dysfunction identified here may represent a unique feature associated with reduced optimism and increased worry about everyday events in GAD. Consistent with this possibility, patients with SAD did not show such dysfunction. Future studies should consider if this dysfunction represents a biomarker for GAD.
Social anxiety disorder involves fear of social objects or situations. Social referencing may play an important role in the acquisition of this fear and could be a key determinant in future biomarkers and treatment pathways. However, the neural underpinnings mediating such learning in social anxiety are unknown. Using event-related functional magnetic resonance imaging, we examined social reference learning in social anxiety disorder. Specifically, would patients with the disorder show increased amygdala activity during social reference learning, and further, following social reference learning, show particularly increased response to objects associated with other people's negative reactions?
A total of 32 unmedicated patients with social anxiety disorder and 22 age-, intelligence quotient- and gender-matched healthy individuals responded to objects that had become associated with others’ fearful, angry, happy or neutral reactions.
During the social reference learning phase, a significant group × social context interaction revealed that, relative to the comparison group, the social anxiety group showed a significantly greater response in the amygdala, as well as rostral, dorsomedial and lateral frontal and parietal cortices during the social, relative to non-social, referencing trials. In addition, during the object test phase, relative to the comparison group, the social anxiety group showed increased bilateral amygdala activation to objects associated with others’ fearful reactions, and a trend towards decreased amygdala activation to objects associated with others’ happy and neutral reactions.
These results suggest perturbed observational learning in social anxiety disorder. In addition, they further implicate the amygdala and dorsomedial prefrontal cortex in the disorder, and underscore their importance in future biomarker developments.
Mechanical property degradation due to an ordering phase transformation is a concern for alloys based on the Ni-Cr binary system (e.g., 690, 625), particularly in nuclear power applications, such as stream generator tubing, reactor pressure vessel and head control rod drive mechanism penetrations, where component lifetimes can exceed 40 years. In the present research, the disorder-order phase transformation has been studied in Ni-Cr model alloys with varying stoichiometry by experimental methods. In this paper, the effect of composition on ordering is characterized via X-ray diffraction.
Outbreak of Mycobacterium tuberculosis infections associated with acupuncture has not been reported. Thirteen patients with a painful swollen lump were referred to our hospital. The index patient received acupuncture and paraspinal muscular injection at a local acupuncture clinic in April 2011 and was diagnosed with M. tuberculosis 1 month later. From May 2011 to August 2011, 12 more patients with a swollen lump on the nuchal region or in the lower back or the buttocks region were referred to our hospital. Tuberculin skin test (TST), T-SPOT.TB, acid-fast stain, M. tuberculosis culture, chest radiograph, and lump magnetic resonance imaging (MRI) were performed and the patients were diagnosed with tuberculous abscess of the lump. All 13 patients received intramuscular injection at the paraspinal muscle by two acupuncturists at a local clinic and reported a swollen lump at the injection site. The needles and syringes were reused after autoclave sterilization. The TST was positive in all patients. Twelve patients had positive acid-fast stains. Mycobacterial cultures of abscess specimens were positive in all 13 patients. T-SPOT.TB tests were positive in all patients who underwent the test. The lesions and biopsies were subjected to polymerase chain reaction (PCR) and gene sequencing by the Disease Control Center of Zhejiang Province, China and the causative agent was identified as M. tuberculosis, Beijing type. In conclusion, physicians should consider the possibility of mycobacterial infections, apart from other bacterial agents, in patients with a swollen paraspinal lump following intramuscular injection.
The electrochemical effects of embedding Cu nanoparticles in carbonized wood supercapacitor electrodes have been investigated. The nanoparticles were embedded using a solution method. Subsequent X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that the Cu nanoparticles were anchored uniformly on the surface and deep within the pores of the electrode. Cyclic voltammetry measurements showed that the electrode has typical pseudocapacitive behavior, with two pairs of redox reaction peaks. The charge-discharge cycling also indicated that the redox charge transformation was a reversible process. An ultra-high specific capacitance of 888 F/g and an energy density of 123 Wh/kg were observed for the Cu loaded electrodes, as compared to the pure carbonized wood electrodes, which had a specific capacitance of 282 F/g and an energy density of 39 Wh/kg. Furthermore, both the carbonized wood and Cu loaded electrodes exhibited excellent long cycle abilities with at least 95% of the specific capacitance retained after 2000 cycles. These remarkable results demonstrate the potential for using Cu nanoparticle loaded carbonized wood as a high performance and environmentally friendly supercapacitor electrode material.
Recently, Fickenscher et al.  have shown that, in a core-multi-shell structure where a GaAs quantum well is embedded into an AlGaAs shell wrapped around a  oriented GaAs nanowire, the electron and hole ground states are strongly confined to the corners of the hexagonally symmetric quantum well. Thus this confinement defines quantum wires which run along the length of the nanowires along its corners. Here we review single nanowire photoluminescence measurements which show the significant confinement energy of the excitons. For well widths larger than 5 nm, optical transitions between electron and hole excited states can be seen in excitation spectra, while for widths less than 5 nm only the ground state optical transitions are observed. For well widths smaller than 5 nm, high resolution spatially resolved photoluminescence measurements show directly the appearance of localized states. Single nanowire spectra from the 4 nm QWT sample display ultranarrow emission lines on the high energy side of the luminescence band. Spatially-resolved PL images show that these quantum dots are localized randomly along the length of the wire.
Recent experimental evidence on nano-particle and nano-wire silicon anodes showed an initial rapid velocity of reaction front at the initial stage of lithiation, followed by an apparent slowing or even halting of the reaction front propagation. This intriguing phenomenon is attributed to the lithiation-induced mechanical stresses across the reaction front which is believed to play an important role in the kinetics of reaction at the front. Here, through theoretical formulation, we presented a comprehensive study on lithiation-induced stress field and its contribution to the driving force of lithiation in hollow spherical anodes with different boundary conditions at the inner surface of the particle. Our results reveal that hollow spherical silicon anodes can be lithiated more easily than solid spherical silicon particles and thus may serve as an optimal design of high performance anodes of lithium-ion battery.
Extensively drug resistant (XDR) Acinetobacter baumannii infections are increasing. Knowledge of risk factors can help to prevent these infections.
We designed a 1: 1: 1 case-case-control study to identify risk factors for XDR A. baumannii bacteremia in Singapore and Thailand. Case group 1 was defined as having infection due to XDR A. baumannii, and case group 2 was defined as having infection due to non-XDR A. baumannii. The control group comprised patients with blood cultures obtained to determine possible infection.
There were 93 patients in each group. Pitt bacteremia score (adjusted odds ratio [aOR], 2.570 [95% confidence interval (CI), 1.528–4.322]), central venous catheters (CVCs; aOR, 12.644 [95% CI, 2.143–74.620]), use of carbapenems (aOR, 54.391 [95% CI, 3.869–764.674]), and piperacillin-tazobactam (aOR, 55.035 [95% CI, 4.803–630.613]) were independently associated with XDR A. baumannii bacteremia. In case group 2, Pitt bacteremia score (aOR, 1.667 [95% CI, 1.265–2.196]) and third-generation cephalosporins (aOR, 2.965 [95% CI, 1.224–7.182]) were independently associated with non-XDR A. baumannii bacteremia. Concurrent infections (aOR, 3.527 [95% CI, 1.479–8.411]), cancer (aOR, 3.172 [95% CI, 1.135–8.865]), and respiratory source (aOR, 2.690 [95% CI, 1.160–6.239]) were associated with an increased risk of 30-day mortality. Survivors received more active empirical therapy (16.7% vs 9.6%; P = .157), had fewer cases of XDR bacteremia (45.8% vs 52.6%; P = .452), and received higher median definitive polymyxin B doses (840,000 units vs 700,000 units; P = .339)
Use of CVC and broad spectrum antibiotics were unique risk factors of XDR A. baumannii bacteremia. Effective antimicrobial stewardship together with use of a CVC bundle may reduce the incidence of these infections. Risk factors of acquisition and mortality may help identify patients for early initiation of polymyxin B therapy.
Except for a single case report, musical ear syndrome in cochlear implantees has not been studied. We aimed to study the prevalence and nature of musical ear syndrome among adult cochlear implant patients, as well as the effect on their emotional well-being.
Study design, patients and intervention:
A cross-sectional survey of patients aged 18 years and above who had received cochlear implants for profound hearing loss between 1997 and 2010.
Of the 82 patients studied, 18 (22 per cent) were found to have experienced musical ear syndrome. Seven and 11 patients had musical ear syndrome prior to and after cochlear implantation, respectively. The character of musical ear syndrome symptoms was described as instrumental music (n = 2), singing (6) or both (10). Fourteen patients reported an adverse emotional effect, with three expressing ‘intolerance’.
In this study, 22 per cent of cochlear implantees experienced musical ear syndrome. These symptoms affected patients' emotional state, but most coped well. Musical ear syndrome can occur prior to and after cochlear implantation.
We have synthesized single-crystal epitaxial MgZnO films by pulsed-laser deposition. High-resolution transmission electron microscopy, X-ray diffraction and Rutherford backscattering spectroscopy/ion channeling were used to characterize the microstructure, defect content, composition and epitaxial single-crystal quality of the films. In these films with up to ∼ 34 atomic percent Mg incorporation, an intense ultraviolet band edge photoluminescence at room temperature and 77 K was observed. The highly efficient photoluminescence is indicative of the excitonic nature of the material. Transmission spectroscopy revealed that the excitonic structure of the alloys was clearly visible at room temperature. Post-deposition annealing in oxygen reduced the number of defects and improved the optical properties of the films. The potential applications of MgZnO alloys in a variety of optoelectronic devices are discussed.
This paper proposes a complete basis set for analyzing elastic wave scattering in half-space. The half-space is an isotropic, linear, and homogeneous medium except for a finite inhomogeneity. The wave bases are obtained by combining buried source functions and their reflected counter-waves generated from the infinite-plane boundary. The source functions are the vector wave functions of infinite-space. Based on the source functions expressed in the Fourier expansion form, the reflected counter-waves are easily obtained by solving the infinite-plane boundary conditions. Few representations adopt Wely's integration, but the Fourier expansion is developed from it and applied to decouple the angular-differential terms of the vector wave functions. In addition to the scattering of the finite inhomogeneity, the transition matrix method is extended to express the surface boundary conditions. For the numerical application in this paper, the P- and the SV- waves are assumed as the incoming fields. As an example, this paper computes stress concentrations around a cavity. The steepest-descent path method yielding the optimum integral paths is used to ensure the numerical convergence of the wave bases in the Fourier expansion. The resultant patterns from these approaches are compared with those obtained from numerical simulations.
Quantum confined nanostructures of semiconductors such as Ge and Si are being actively studied due to their interesting optical and electronic transport properties. We fabricated Ge nanostructures buried in the matrix of polycrystalline-AIN grown on Si(111) by pulsed laser deposition at lower substrate temperatures than that used in previous studies. The characterization of these structures was performed using high resolution transmission electron microscopy (HRTEM), photoluminescence and Raman spectroscopy. HRTEM observations show that the Ge islands are single crystal with a pyramidal shape. The average size of Ge islands was determined to be 15 nm, considerably smaller than that produced by other techniques. The Raman spectrum reveals a peak downward shift, upto 295 cm−1, of the Ge-Ge mode caused by quantum confinement in the Ge-dots. Photoluminescence (PL) was observed both with a single layer of Ge nanodots embedded in the AlN matrix and from ten layers of dots interspersed with AIN. The PL of the dots was blue shifted by ˜0.266 eV from the bulk Ge value of 0.73 eV at 77 K, resulting in a distinct peak at ˜1.0 eV. The full width at half maximum (FWHM) of the peak was 13 meV, for the single layer and 8 meV for the ten layered sample, indicating that the Ge nanodots are fairly uniform in size, which was found to be consistent with our HRTEM results. The importance of pulsed laser deposition (PLD) in fabricating novel nanostructures is discussed.
In healthy older subjects, the glycaemic response to carbohydrate-containing meals is dependent on gastric emptying and intestinal absorption; when the latter is slowed, the magnitude of the rise in glucose is attenuated. The oligosaccharide α-cyclodextrin has been reported to diminish the glycaemic response to starch in young adults; this effect has been attributed to the inhibition of pancreatic amylase. We examined the effects of α-cyclodextrin on gastric emptying of, and the glycaemic and insulinaemic responses to, oral sucrose in healthy older subjects; as sucrose is hydrolysed by intestinal disaccharides, any effect(s) of α-cyclodextrin would not be attributable to amylase inhibition. A total of ten subjects (seven males and three females, age 68–76 years) were studied on 2 d. Gastric emptying, blood glucose and serum insulin were measured after ingestion of a 300 ml drink containing 100 g sucrose, labelled with 99mTc-sulphur colloid, with or without 10 g α-cyclodextrin. Gastric emptying was slowed slightly by α-cyclodextrin; this effect was evident between 135 and 195 min and was associated with a slight increase (P < 0·05) in distal stomach retention. After α-cyclodextrin, blood glucose was slightly less (P < 0·05) at 60 min, and serum insulin was less (P < 0·0005) at 90 and 120 min. There was no difference in the incremental areas under the curve (iAUC) for blood glucose, but there was a trend for the iAUC for serum insulin to be lower (P = 0·09) after α-cyclodextrin. We conclude that in a dose of 10 g, α-cyclodextrin has modest effects to slow gastric emptying of, and modify the glycaemic and insulinaemic responses to, oral sucrose, probably due to delayed intestinal carbohydrate absorption.
We report an interesting property of carbon dots: they emit light under charge injection. We synthesized carbon dots in diameter about 20 nm using wet chemistry methods. The photoluminescence quantum efficiency of the carbon dots dissolved in water was about 11%. We observed strong electrogenerated chemiluminescence (ECL) from the sample. This observation of ECL from carbon dots indicates that they could be a good candidate material for carbon-based electroluminescent devices.
We have synthesized new cubic phase of ZnxMg1−xO alloy, which can be grown epitaxially on MgO (100) by lattice-matching epitaxy, and on Si (100) substrate by our domainmatching epitaxy for integration with silicon microelectronic devices. Cubic ZnxMg1−xO films on MgO (100) and Si (100) substrates were grown using a rotating target in a single chamber “insitu” pulsed-laser deposition system. Integration of ZnxMg1−xO films with silicon was accomplished via titanium nitride (TiN) buffer layers where four lattice constants of TiN match with three of the silicon during epitaxial growth via domain epitaxy. Rutherford backscattering/ion channeling techniques were used to determine chemical composition and crystalline quality of the films for x = 0.0-0.18. Detailed X-ray diffraction and transmission electron microscopy studies confirmed the epitaxial nature of ZnMgO/MgO (100) and ZnMgO/TiN/Si (100) heterostructures, and showed the formation of the Mg2−xZnxTiO4 spinel at the interface with TiN. Using optical transmission measurements, the band gap of cubic Zn0.18Mg0.82O film was estimated to be approximately 6.7 eV. The potential use of these alloys for optical devices in the ultraviolet range is discussed.
We have synthesized ZnMgO alloy of wurtzite (Mg content equals to 0.0=0.34) and cubic (Zn content equals to 0.0- 0.18) phases using nonequilibrium pulsed laser deposition method. Epitaxial films of ZnMgO wurtzite structure have been grown on (0001) sapphire substrates. Using JEOL-2010 field-emission transmission electron microscope equipped with STEM and Gatan image filter, we can perform atomic structure, STEM-Z, electron energy loss spectroscopy and imaging simultaneously. Such studies on the ZnO/MgZnO superlattices provide first direct evidence of phase-separation in the range 3 nm.
Second order non-linear optical (NLO) polymers have been the focus of intense research effort in recent years . This effort is justified by the potential value of these materials in a range of attractive optical signal processing applications with lower device costs and enhanced device performance.
We propose a new approach, growth on compliant substrates, to achieve extended pseudomorphic limits. The compliant substrate can be approximately achieved with a corner supported membrane structure. Both thermal equilibrium model and dynamic model considering strain relaxation are used to analyze the relations between the extended critical thickness and the substrate thickness. Preliminary experimental results of InGaAs grown on GaAs membranes seem to support the theories.
Although organic crystals may be used to experimentally verify the large nonlinearities and short response times of organics, such crystals are not acceptable for device applications due to significant fabrication difficulties. Further, the bulk material nonlinearity is a function of molecular orientation and symmetry which may not be controlled during the crystallization process.
Nonlinear optical polymers have been synthesized at Hoechst Celanese for which the active NLO unit is attached to the polymer backbone as a pendant side chain. Control of orientation and symmetry of the unit is achieved by poling in an external electric field at elevated temperatures resulting in second order susceptibilities larger than inorganic crystals. The polymers have attractive secondary properties (i.e., optical transparency, high glass transition temperatures which are controlled by adjusting the side chain length and nature of the polymer backbone, low dielectric constants, and flat frequency respose). Further, single mode waveguides may be fabricated by spin coating. Deposition of electrodes on the waveguide permits application of an external field which changes the material's index of refraction due to the linear electrooptical effect. Thus, a host of electrooptical waveguide devices may be constructed which operate at low voltages and very high frequencies.