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Serotonin transporter (SERT) and dopamine transporter (DAT) levels differ in patients with major depressive disorder (MDD) who are in a depressed state in comparison with healthy controls. In addition, a family history of depression is a potent risk factor for developing depression, and inherited vulnerability to serotonergic and dopaminergic dysfunction is suspected in this. The aim of this study was to examine the availabilities of midbrain SERT and striatal DAT in healthy subjects with and without a first-degree family history of MDD.
Eight healthy subjects with first-degree relatives with MDD and 16 sex- and age-matched healthy controls were recruited. The availabilities of SERT and DAT were approximated using SPECT, employing [123I] 2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine (ADAM) and [99mTc] TRODAT-1 as the ligands, respectively. There are missing data for one participant with a first-degree family history of MDD from the ADAM study, due to a lack of the radio-ligand at the time of experiment.
SERT availability in the midbrain was significantly lower in subjects with a first-degree family history of MDD than in healthy subjects. However, DAT availability was no different between two groups.
The results with regard to the midbrain SERT level suggest the heritability of MDD.
There has been increasing interest from industry to characterize the different precipitate distributions in ferrous materials to account for different mechanical properties that are observed. For this study, two different heat treatments were chosen for the experimental S5 tool steel, modified to have 0.24 wt% C. Alloy S5-1 received 1 hour of austenitizing at 970°C, was quenched at rate of 140°C/s and tempered for 1 hour at 200°C. Alloy S5-2 received 40 minutes of austenitizing at 940°C, was quenched at rate of 16°C/s and tempered for 1 hour at 200 °C. In this relatively low hardenability steel, both S5-1 and S5-2 show mixed microstructures of tempered martensite and bainite (Fig. 1, 2). Not surprisingly, the slower cooling rate for S5-2 created an alloy with inferior microstructure and mechanical properties. Even though these differences in precipitate distributions, could not directly account for differences in mechanical properties, it is of interest to study how the different heat treatments affected the precipitate distributions in S5-1 and S5-2.
Over an order of magnitude reduction in dark current was observed for gas-source molecular beam epitaxially (GSMBE) grown, lattice-matched n- and p-type InGaAs/InP quantum-well infrared photodetectors (QWIPs). Peak spectral response at 8.93 and 4.55 μm for n- and p-type QWIPs, respectively, open the possibility of dual-band monolithic integration under identical GSMBE growth conditions.
A systematic study of the structural properties and defect distribution of GaAs layers grown by metalorganic chemical vapor deposition on Si substrates misoriented 1°, 1.5°, 2°, 4°, and 6° from  toward  is reported. Double crystal x-ray rocking curves, cross-section and plan-view Transmission Electron Microscopy (TEM) are used to characterize the structural strain and defect distribution of as-grown and annealed GaAs layers. Both strain and defect density in the GaAs layers are found to be dependent of the degree of substrate misorientation as well as the direction in which measurements are made. Plan-view TEM shows an asymmetric distribution of microtwins in two perpendicular directions. There exists a correlation between the directionality of the strain and of the defect density. Furnace annealing at 850°C for 30 minutes in an arsine overpressure can reduce significantly the defects, the strain and the strain anisotropy. It is found that microtwins are of the highest density when the substrate is misoriented about 4 degrees for the as-grown samples. Though a reduction of defects after annealing occurs for all samples, the least misoriented one shows the most improvement.
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