Two structural domains of initiation factor eIF-4B are involved in binding to RNA

Translation initiation factor eIF-4B promotes the binding of mRNA to 40 S preinitiation complexes and together with eIF-4A possesses RNA helicase activity. To elucidate structural features involved in its function, a series of internal and C-terminal deletions, as well as point mutations, were constructed in the eIF-4B cDNA. The mutated cDNAs were expressed in transiently transfected COS-1 cells, and mutant forms of the factor were overproduced up to about 25-fold over endogenous eIF-4B levels. Inhibition of dihydrofolate reductase (DHFR) synthesis by high levels of eIF-4B variants was determined in vivo, and the binding of the eIF-4B forms to biotinylated RNA was measured in vitro. The results indicate that the N-terminal region containing the RNA binding motif with its RNP1 and RNP2 consensus elements is sufficient for inhibition of DHFR synthesis. Deletion of the RNP1 sequence abrogates RNA binding, but amino acid substitutions at conserved residues do not always inhibit RNA binding. Deletion of the DRYG domain near the middle of eIF-4B results in inhibition of RNA binding, but not of DHFR synthesis. Up to 164 residues of the C terminus are not required for RNA binding, but removal of 226 or more residues completely inhibits RNA binding, perhaps by the loss of two arginine-rich regions. The results suggest that both the RNA recognition motif and the arginine-rich region are required for stable RNA binding but that both are not necessary for in vivo inhibition of protein synthesis.     

Parallelisation of suboptimal spectrum search

The authors suggest that effective algorithms for spectrum search, such as those used for detecting spread spectrum signals, may be derived by selecting suboptimal algorithms and then recovering some of the lost efficacy through parallelisation methods. This thesis is motivated by considering a simple yet meaningful example of a spectrum search technique that exhibits what at first may seem to be counterintuitive behaviour.<>     

Error rate for optimal follower tone-jamming

The performance of a countermeasure technique in the presence of the optimal follower multitone jammer is evaluated for frequency-hopped spread spectrum (FHSS) communications. It is shown that, with a certain probability, the optimal jammer will have dual tones in a frequency channel     

Comparison of three rewarming methods in a postanesthesia care unit

Postoperative hypothermia is problematic because patients in postanesthesia care units (PACUs) often feel very cold, and unrecognized or prolonged postoperative hypothermia can aggravate patients' underlying cardiovascular disorders. The researchers compared three methods of rewarming PACU patients who had undergone laparotomy procedures. Patients were assigned randomly to three groups. Each patient in group one received the standard PACU rewarming intervention (ie, two warmed thermal blankets and a hospital bedspread). Each patient in group two received the standard PACU rewarming intervention plus a reflective blanket. Each patient in group three received the standard PACU rewarming intervention plus a reflective blanket and a reflective head covering. Nurses measured patients' vital signs on admission to the PACU and every 15 minutes thereafter until patients' sublingual temperatures reached 36 degrees C (96.8 degrees F). No significant temperature differences occurred among patients in the three groups, but an inverse relationship existed between patients' PACU admission temperatures and the time they required to reach normothermia.     

Numerical study of steady turbulent flow through bifurcated nozzles in continuous casting

Bifurcated nozzles are used in continuous casting of molten steel, where they influence the quality of the cast steel slabs. The present study performs two-dimensional (2-D) and three-dimensional (3-D) simulations of steady turbulent(K- ε) flow in bifurcated nozzles, using a finite-element (FIDAP) model, which has been verified previously with water model experiments. The effects of nozzle design and casting process operating variables on the jet characteristics exiting the nozzle are investigated. The nozzle design parameters studied include the shape, angle, height, width, and thickness of the ports and the bottom geometry. The process operating practices include inlet velocity profile and angle as well as port curvature caused by erosion or inclusion buildup. Results show that the jet angle is controlled mainly by the port angle but is steeper with larger port area and thinner walls. The degree of swirl is increased by larger or rounder ports. The effective port area, where there is no recirculation, is increased by smaller or curved ports. Flow asymmetry is more severe with skewed or angled inlet conditions or unequal port sizes. Turbulence levels in the jet are higher with higher casting speed and smaller ports. Formerly Research Assistant, Department of Mechanical and Industrial Engineering. Formerly Research Assistant in the same department.     

Altered thalamic response to levodopa in Parkinson's patients with dopa-induced dyskinesias

Parkinson's disease (PD) is a progressive neurologic condition characterized by tremor, slowness, stiffness, and unstable posture. Degeneration of dopamine-producing neurons in the substantia nigra causes PD. Treatment with levodopa, a precursor of dopamine, initially ameliorates the clinical manifestations of PD. However, chronic levodopa treatment can produce severe involuntary movements (so-called dopa-induced dyskinesias or DID), limiting treatment. Pallidotomy, placement of a surgical lesion in the internal segment of the globus pallidus, reduces DID. Because this result is inconsistent with current theories of both basal ganglia function and DID, it prompted us to investigate the brain's response to levodopa. We measured regional cerebral blood flow response to levodopa with positron-emission tomography in 6 PD patients with DID, 10 chronically treated PD patients without DID, 17 dopa-na?ve PD patients, and 11 normals. The dose of levodopa was chosen to produce clinical benefit without inducing DID. This strategy allowed us to examine the brain response to levodopa across groups without the confounding effect of differences in motor behavior. We found that the DID group had a significantly greater response in ventrolateral thalamus than the other groups. This was associated with decreased activity in primary motor cortex. These findings are consistent with increased inhibitory output from the internal segment of the globus pallidus to thalamus after levodopa administration. They provide a physiological explanation for the clinical efficacy of pallidotomy and new insights into the physiology of the basal ganglia.     

Modest but useful erasure technique for DPSK

A simple selective erasure forward error correction (FEC) technique for differential phase shift keyed (DPSK) data is presented. The method provides a modest coding gain and requires very little overhead and computation. It is very similar to the Wagner code and may be useful as a stand alone technique in some applications and as a preconditioner to more sophisticated FEC techniques in others     

Effects of anticipated job loss on employee behavior.

Compared the behavior (i.e., productivity, absenteeism, and lateness) of 100 employees who knew that they were to be laid off or not laid off. No significant changes in the absenteeism, lateness, or production were found in either group during the 3-mo period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accuracy of employee reports on changes in pay.

To test the validity of perceived change measures, questionnaires were administered to 246 employees before and after automation. Actual and perceived change in pay was the one aspect of change studied. "Data are presented on the degree of accuracy of employee reports, on the nature of the deviations between reports and actuality, and on the relationship of the deviations to potential explanatory variables." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unconventional cryptographic keying variable management

We present three unconventional approaches to keying variable management. The first approach is based on using a public key cryptosystem (PKC) that is breakable in short, but on average less, time than it takes to set up an ultrawide bandwidth modem that is then used to transport a keying variable for a classical cryptosystem. The second concept proposes using the characteristics of an urban UHF radio channel, determined by mutual sounding, as the cryptovariable. The third concept encourages research into ill-conditioned problems as potentially fruitful ground for PKCs not based on finite field arithmetic