RNA-protein interactions within the 3 ' untranslated region of vimentin mRNA

Several functions have been attributed to protein binding within the 3'untranslated region (3'UTR) of mRNA, including mRNA localization, stability, and translational repression. Vimentin is an intermediate filament protein whose 3'untranslated sequence is highly conserved between species. In order to identify sequences that might play a role in vimentin mRNA function, we synthesized32P-labeled RNA from different regions of vimentin's 3'UTR and assayed for protein binding with HeLa extracts using band shift assays. Sequences required for binding are contained within a region 61-114 nucleotides downstream of the stop codon, a region which is highly conserved from Xenopus to man. As judged by competition assays, binding is specific. Solution probing studies of 32P-labeled RNA with various nucleases and lead support a complex stem and loop structure for this region. Finally, UV cross-linking of the RNA-protein complex identifies an RNA binding protein of 46 kDa. Fractionation of a HeLa extract on a sizing column suggests that in addition to the 46 kDa protein, larger complexes containing additional protein(s) can be identified. Vimentin mRNA has been shown to be localized to the perinuclear region of the cytoplasm, possibly at sites of intermediate filament assembly. To date, all sequences required for localization of various mRNAs have been confined to the 3'UTR. Therefore, we hypothesize that this region and associated protein(s) might be important for vimentin mRNA function such as in localization.     

Sex differences in olfactory identification and Wisconsin Card Sorting performance in schizophrenia: relationship to attention and verbal ability

We investigated the hypothesis that different prefrontal brain systems (i.e., dorsal vs. ventral) and sex contribute differentially to cognitive deficit in schizophrenia. Performance was assessed among clinically stable, chronic schizophrenic outpatients and matched normal control subjects on olfactory identification [on the University of Pennsylvania Smell Identification Test (UPSIT)] and on executive functions [using the Wisconsin Card Sorting Test (WCST)]. Patients were impaired on both tests compared to controls, and male schizophrenics were impaired on the WCST compared to female schizophrenics. The pattern of results suggests that gender differences on the UPSIT are mildly accentuated in schizophrenia. The data support our previous study indicating that UPSIT performance is largely independent of the executive or attentional deficits typically associated with schizophrenia, with the exception of verbal ability. Further research with larger samples is required to test the hypothesis that there is a severely impaired subgroup of male patients with diffuse prefrontal dysfunctions.     

Low-bias performance of avalanche photodetector. A time-domainapproach

The performance of the InP-InGaAs avalanche photodiode (APD) at low bias voltages has been investigated directly from its impulse response without using any fitting parameters. The important mechanisms responsible for low-bias performance are the emission of holes from the InP-InGaAs interface potential-trap in the valence band, the velocity of the carriers, and the diffusion of photogenerated holes from the undepleted region to the depleted region of the absorption layer. A time-recurrence relation for the emission of holes from the trap has been derived and special attention has been paid to the velocity of carriers at low fields. The delay in the process of diffusion of photogenerated holes has been taken into account in obtaining the impulse response. The bandwidth at different gains have been calculated by taking the fast Fourier transform (FFT) of the current impulse response. The gain-bias and gain-bandwidth characteristics show reasonably good agreement between the data from the model and the experimental data of an earlier published work on InP-InGaAs APD     

Overview of the Mars Pathfinder mission and assessment of landing site predictions

Chemical analyses returned by Mars Pathfinder indicate that some rocks may be high in silica, implying differentiated parent materials. Rounded pebbles and cobbles and a possible conglomerate suggest fluvial processes that imply liquid water in equilibrium with the atmosphere and thus a warmer and wetter past. The moment of inertia indicates a central metallic core of 1300 to 2000 kilometers in radius. Composite airborne dust particles appear magnetized by freeze-dried maghemite stain or cement that may have been leached from crustal materials by an active hydrologic cycle. Remote-sensing data at a scale of generally greater than approximately 1 kilometer and an Earth analog correctly predicted a rocky plain safe for landing and roving with a variety of rocks deposited by catastrophic floods that are relatively dust-free.     

Channel noise modeling of deep submicron MOSFETs

This brief presents a new channel noise model using the channel length modulation (CLM) effect to calculate the channel noise of deep submicron MOSFETs. Based on the new channel noise model, the simulated noise spectral densities of the devices fabricated in a 0.18 /spl mu/m CMOS process as a function of channel length and bias condition are compared to the channel noise directly extracted from RF noise measurements. In addition, the hot electron effect and the noise contributed from the velocity saturation region are discussed.     

Interfacial study of magnesium-containing fluoridated hydroxyapatite coatings

Magnesium-containing fluoridated hydroxyapatite (Mg_xFHA) coatings have been developed to improve the biological performances of fluoridated hydroxyapatite (FHA) coatings. The coatings are deposited on Ti6Al4V substrates via a sol-gel process. The interface between the coating and substrate is characterized by scanning electron microscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy for coating thickness, elemental distribution and chemical states. Pull-off test is used to evaluate the adhesion strength. The results show that the interdiffusion of elements happens at the coating/substrate interface. The incorporation of Mg ions into FHA coatings enhances the pull-off adhesion strength between the coating and the substrate, but no significant difference is observed with different Mg concentrations.