Terahertz detection using the free-carrier absorption requires a small internal work function of the order of a few millielectron volts. A threshold frequency of 3.2 THz (93 microm or approximately 13 meV work function) is demonstrated by using a 1 x 10(18) cm(-3) Si-doped GaAs emitter and an undoped Al(0.04)Ga(0.96)As barrier structure. The peak responsivity of 6.5 A/W, detectivity of 5.5 x 10(8) Jones, and quantum efficiency of 19% were obtained at 7.1 THz under a bias field of 0.7 kV/cm at 6 K, while the detector spectral response range spans from 3.2 to 30 THz.

Proximal spinal muscular atrophy (SMA) is a neurodegenerative disorder caused by deficiency of the ubiquitous Survival of Motor Neuron (SMN) protein. SMN has been shown to be transported in granules along the axon and moved through cytoskeletal elements. However, the role and nature of SMN granules are still not well characterized. Here, using immunocytochemical methods and time-lapse studies we show that SMN granules colocalize with the Golgi apparatus in motor neuron-like NSC34 cells. Electron microscopy clearly revealed that SMN granules are transported into the Golgi stack and aggregate in the trans-Golgi apparatus. SMN granules are characterized as either coated or un-coated and behave like regulated secretory granules. Treatment of cells with monensin to disrupt Golgi-mediated granule secretion decreased SMN expression in neurites and caused growth cone defects similar to those seen in SMN knockdown cells. Knockdown of Cop-α, the protein that coats vesicles transporting proteins between the Golgi compartments, caused SMN granule accumulation in the Golgi apparatus. In addition to the well-studied role of SMN in small nuclear ribonucleoprotein (SnRNP) assembly, this work links SMN granules with the Golgi network and thus sheds light on Golgi-mediated SMN granule transport.

a b s t r a c tPurpose: The purpose of this study was to assess the amount of variance in the coping strategies of patients with brain tumors that could be accounted for by resilience. Methods: This cross-sectional survey involved 95 patients who had experienced surgical, chemotherapy, or radiotherapy therapies for their brain tumors at least 1 month before data collection. The investigator collected data using the scales of the Ways of Coping Checklist-Revised and Resilience Scale. Data were analyzed using descriptive statistics, t tests, analysis of variance, Pearson productemoment correlation, and hierarchical multiple regression. Results: The results revealed that resilience was significantly positively associated with patients' problem-focused coping (r ¼ .65, p < .001) and total coping (r ¼ .49, p < .001). In addition, resilience accounted for 27% (R 2 inc ¼ .27, p < .001) and 16% (R 2 inc ¼ .16, p < .001) of the distinct variances in predicting patients' problem-focused coping and total coping. Conclusion: The current results provide evidence to support the importance of resilience in shaping the coping strategies of relevant patients. As resilience shows a crucial element in patient coping with brain tumors, health team members should develop and employ appropriate strategies to improve the resilience of patients with brain tumors.

We report the nonlinear behavior of quantum-well infrared photodetectors with three energetically equidistant energy levels. The giant resonant nonlinearity leads to a quadratic power dependence of the photocurrent down to excitation power densities as low as 0.1 W/cm2. Using these highly sensitive two-photon detectors, second-order autocorrelation measurements of ultrashort midinfrared laser pulses in the pJ regime are demonstrated. The dynamical behaviour is studied by a numerical analysis of these measurements. At high bias voltages we observe a dominating linear contribution to the photocurrent arising from tunnelling processes