On the effect of time-dependent deformations on the behaviour of patch-repaired reinforced concrete short columns

This paper reports the results of an experimental study of the effect of time-dependent deformations (such as shrinkage and creep) of concrete repair materials on the ability of patch repairs to contribute to the structural function of reinforced concrete short columns. Prior to repair, strain measurements were taken from loaded columns with preformed cavities; cavity depths varied between columns. One polymeric and one polymer-modified concrete repair material were used for repair, all repairs being performed under zero load. After repair, the distribution of strain was measured from columns subjected to axial service load and from similar columns observed under zero load. Test results indicate that in the short term both the repair materials assist the repaired column to carry load, but in the long term the contribution of the polymer-modified material is reduced substantially while that of the polymeric material is sustained. It is observed that shrinkage of the repair material can induce bending in the repaired column and that this bending increases with patch repair cavity depth. Within the repaired zone, bending strain distributions were linear which would suggest that conventional methods of structural analysis are appropriate for such members.     

Application of enhancement mode FET technology for wirelesssubscriber transmit/receive circuits

Single-supply power amplifiers have become the new paradigm in portable phone handsets due to the recent availability of heterojunction bipolar transistor (HBT) and pseudo enhancement mode PHEMT technology. We have developed a true enhancement mode heterostructure insulated-gate FET device (HIGFET) which is suitable for use in both saturated and linear power amplifiers. A three-stage power amplifier designed for 1900-MHz NADC application delivered +30-dBm output power and 41.7% power-added efficiency with an adjacent channel power of -29.8 dBc and alternate adjacent channel power of -48.4 dBc. In addition to this, we have demonstrated excellent noise figure and linearity performance for small-signal applications. At 900 MHz and bias conditions V_DS=1.0 V and I_DSQ=1 mA, a single-stage amplifier achieved a noise figure of 1.17 dB with an associated gain of 18.5 dB. These results make the technology an ideal candidate for application in both transmitter and receiver circuits     

Plasmonic Luneburg and Eaton lenses

Plasmonics takes advantage of the properties of surface plasmon polaritons, which are localized or propagating quasiparticles in which photons are coupled to the quasi-free electrons in metals. In particular, plasmonic devices can confine light in regions with dimensions that are smaller than the wavelength of the photons in free space, and this makes it possible to match the different length scales associated with photonics and electronics in a single nanoscale device. Broad applications of plasmonics that have been demonstrated to date include biological sensing, sub-diffraction-limit imaging, focusing and lithography and nano-optical circuitry. Plasmonics-based optical elements such as waveguides, lenses, beamsplitters and reflectors have been implemented by structuring metal surfaces or placing dielectric structures on metals to manipulate the two-dimensional surface plasmon waves. However, the abrupt discontinuities in the material properties or geometries of these elements lead to increased scattering of surface plasmon polaritons, which significantly reduces the efficiency of these components. Transformation optics provides an alternative approach to controlling the propagation of light by spatially varying the optical properties of a material. Here, motivated by this approach, we use grey-scale lithography to adiabatically tailor the topology of a dielectric layer adjacent to a metal surface to demonstrate a plasmonic Luneburg lens that can focus surface plasmon polaritons. We also make a plasmonic Eaton lens that can bend surface plasmon polaritons. Because the optical properties are changed gradually rather than abruptly in these lenses, losses due to scattering can be significantly reduced in comparison with previously reported plasmonic elements.     

Crosslinking of apolipoprotein E by products of lipid peroxidation

Apolipoprotein E (APOE) genotype and advancing aging are interacting ri sk factors in the expression of late onset and sporadic Alzheimer's Disease (AD). We tested the hypothesis that 2 products of lipid peroxidation, malondialdehyde (MDA) and 4 hydroxy-2-nonenal (HNE), covalently modify APOE and alter its metabolism. In vitro, both HNE and MDA crosslinked purified APOE3 and APOE4. HNE was a more potent crosslinker than MDA, and purified APO3 was more susceptible to crosslinking by HNE than was purified APOE4. In P19 neuroglial cultures, oxidative stress with lipid peroxidation led to increased intracellular accumulation of anti-HNE and anti-APOE immunoreactive proteins of approximately 50 kDa. Intercellular accumulation of the 50 kDa APOE-immunoreactive protein (APOE-50) was not prevented by cyclohexamide, suggesting formation by post-translational mechanisms. In CSF, a 50 kDa APOE-immunoreactive protein co-migrated with proteins most immunoreactive for HNE and MDA adducts, containing NaB3H4-reducible bonds. These proteins were in CSF from adult subjects (with or without dementia), and in AD patients homozygous for APOE3 or APOE4 alleles. These data suggest that HNE covalently crosslinks APOE in P19 neuroglial cultures to form a 50 kDa protein, and that similar modifications of APOE appear to occur in vivo.     

Salmonella typhimurium encodes an SdiA homolog, a putative quorum sensor of the LuxR family, that regulates genes on the virulence plasmid

OBJECTIVE: Despite improved systemic control of metastatic breast cancer, the incidence of brain metastases from breast carcinoma continues to rise, in part because most systemically administered agents have poor central nervous system penetration. Therefore, as a method of optimizing drug delivery into the central nervous system, we studied the safety and efficacy of chemotherapy delivered locally via biodegradable polymers in a mouse model of breast carcinoma metastases to the brain. METHODS: The chemotherapeutic agents carmustine (BCNU), carboplatin, and camptothecin were incorporated into controlled release polymers and tested individually against intracranial challenges of EMT-6 breast tumor in BALB/c female mice. For each drug, four groups were tested: Group 1, empty polymer (no drug); Group 2, external beam radiotherapy (XRT) alone; Group 3, local chemotherapy from biodegradable polymer alone; and Group 4, local chemotherapy and XRT together. Polymers were implanted 5 days after intracranial tumor inoculation; XRT was administered on Days 7 through 9 (300 cGy/d). RESULTS: BCNU polymer alone (n = 10; median survival time, >200 d; P < 0.0001) and BCNU and XRT together (n = 10; median survival time, 41 d; P = 0.02) significantly improved survival in mice with intracranial EMT-6 breast cancer in comparison with control animals (n = 20; median survival time, 17 d). Carboplatin and camptothecin, either with or without XRT, and XRT alone did not have any significant effect on survival. CONCLUSION: Local delivery of BCNU with biodegradable polymers can significantly prolong survival in a murine model of intracranial metastatic breast cancer. Surgical resection and placement of BCNU polymers into the resection cavity may decrease the incidence of local recurrence of breast cancer metastases with minimal morbidity.     

Analysis of potential risk factors associated with the development of pancreatitis in phase I patients with AIDS or AIDS-related complex receiving didanosine

Phase I dose-escalating trials of didanosine revealed dose-limiting toxicities, including pancreatitis, and established a total daily dose of 12.5 mg/kg/day as the maximum tolerated dose. Clinical and pharmacokinetic data of 61 patients from two trials were analyzed to further evaluate the risk of pancreatitis: 1 (6.3%) of 16 patients who received < 500 mg/day didanosine, 2 (13.3%) of 15 who received 500-750 mg/day, and 15 (50%) of 30 who received > 750 mg/day developed pancreatitis (P < .001). A relationship between risk of pancreatitis and steady-state plasma concentrations of didanosine and age was also observed, suggesting that knowledge of didanosine pharmacokinetics provided additional information regarding risk of toxicity. Further confirmation of these findings will be necessary to determine if the risk factors for pancreatitis remain the same at lower doses currently used.     

Plasminogen deficiency accelerates vessel wall disease in mice predisposed to atherosclerosis

A critical link between hemostatic factors and atherosclerosis has been inferred from a variety of indirect observations, including the expression of procoagulant and fibrinolytic factors within atherosclerotic vessels, the presence of fibrin in intimal lesions, and the cellular infiltration of mural thrombi leading to their incorporation into developing plaques. To directly examine the role of the key fibrinolytic factor, plasminogen, in atherogenesis, plasminogen-deficient mice were crossed to hypercholesterolemic, apolipoprotein E-deficient mice predisposed to atherosclerosis. We report that the loss of plasminogen greatly accelerates the formation of intimal lesions in apolipoprotein E-deficient animals, whereas plasminogen deficiency alone does not cause appreciable atherosclerosis. These studies provide direct evidence that circulating hemostatic factors strongly influence vessel wall disease in the context of a disorder in lipid metabolism.     

Spontaneous bilateral carotid and vertebral artery dissection presenting as a Collet-Sicard syndrome

Spontaneous dissection of the internal carotid arteries usually presents with unilateral headache, neck pain, focal ipsilateral cerebral ischaemic symptoms and a Horner's syndrome. Lower cranial nerve palsies are only rarely observed. We report a case of carotid and vertebral dissections presenting as a unilateral palsy of the ninth to twelfth cranial nerves (Collet-Sicard syndrome).     

Advances in Capacitor Starting

An 8000-hp motor at the LOCAP Pipeline Clovelly Station is brought on line with three step capacitor starting and is protected from resonant overvoltage by a large metal oxide voltage limiter. Three-step starting is required to stay within the utility requirement of a maximum of ±1.5 percent primary voltage fluctuation during the entire starting operation. Cycle timers are utilized to obtain critical breaker sequencing as well as protect the system from breaker failure. Should the utility power fail while the motor is accelerating, the starting capacitor may cause severe motor overvoltage. Zinc oxide limiters are sized to absorb 1 MJ over a period of ten cycles allowing the breakers to clear the motor and capacitors.