An efficient method of radiation attenuation through aircraft cooling vents

Some critical avionic systems require cooling air via vents on the side of the aircraft, thus creating leakage points for high-intensity electromagnetic radiation. This paper presents a novel application of high-intensity radiated field (HIRF) shielding using a rectangular waveguide array, while maintaining cooling airflow requirements. Signal attenuation versus frequency and depth of the array has been calculated using closed-form equations. The simulation and measurement results are in good agreement with the calculated values. (C) 2004 Wiley Periodicals, Inc.

Antimicrobial activity of neuropeptides against a range of micro-organisms from skin, oral, respiratory and gastrointestinal tract sites

Many neuropeptides are similar in size, amino acid composition and charge to antimicrobial peptides. This study aimed to determine whether the neuropeptides substance P (SP), neurokinin A (NKA), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP), displayed antimicrobial activity against Streptococcus mutans, Lactobacillus acidophilus, Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. SP, NPY, VIP and CGRP displayed variable degrees of antimicrobial activity against all the pathogens tested with the exception of S. aureus. These antimicrobial activities add a further dimension to the immunomodulatory roles for neuropeptides in the inflammatory and immune responses. (c) 2008 Elsevier B.V. All rights reserved.

Cooling and changing seasonality in the Southern Alps, New Zealand during the Antarctic Cold Reversal

A comprehensively C-14 AMS dated pollen and chironomid record from Boundary Stream Tarn provides the first chironomid-derived temperature reconstruction to quantify temperature change during Lateglacial times (17,500-10,000 cal yr BP) in the Southern Alps, New Zealand. The records indicate a ca 1000-year disruption to the Lateglacial warming trend and an overall cooling consistent with the Antarctic Cold Reversal (ACR). The main interval of chironomid-inferred summer temperature depression (similar to 2-3 degrees C) lasted about 700 years during the ACR. Following this cooling event, both proxies indicate a warming step to temperatures slightly cooler than present during the Younger Dryas chronozone (12,900-11,500 cal yr BP). These results highlight a direct linkage between Antarctica and mid-latitude terrestrial climate systems and the largely asynchronous nature of the interhemispheric climate system during the last glacial transition. The greater magnitude of temperature changes shown by the chironomid record is attributed to the response of the proxies to differences in seasonal climate with chironomids reflecting summer temperature and vegetation more strongly controlled by duration of winter or by minimum temperatures. These differences imply stronger seasonality at times during the Lateglacial, which may explain some of the variability between other paleoclimate records from New Zealand and have wider implications for understanding differences between proxy records for abrupt climate change. (C) 2007 Elsevier Ltd. All rights reserved.

Identification of the mitochondrial ND3 subunit as a structural component involved in the active/deactive enzyme transition of respiratory complex I

Mitochondrial complex I (NADH: ubiquinone oxidoreductase) undergoes reversible deactivation upon incubation at 30-37 degrees C. The active/deactive transition could play an important role in the regulation of complex I activity. It has been suggested recently that complex I may become modified by S-nitrosation under pathological conditions during hypoxia or when the nitric oxide: oxygen ratio increases. Apparently, a specific cysteine becomes accessible to chemical modification only in the deactive form of the enzyme. By selective fluorescence labeling and proteomic analysis, we have identified this residue as cysteine-39 of the mitochondrially encoded ND3 subunit of bovine heart mitochondria. Cysteine-39 is located in a loop connecting the first and second transmembrane helix of this highly hydrophobic subunit. We propose that this loop connects the ND3 subunit of the membrane arm with the PSST subunit of the peripheral arm of complex I, placing it in a region that is known to be critical for the catalytic mechanism of complex I. In fact, mutations in three positions of the loop were previously reported to cause Leigh syndrome with and without dystonia or progressive mitochondrial disease.

Salbutamol up-regulates matrix metalloproteinase-9 in the alveolar space in the acute respiratory distress syndrome.

Objectives: Acute respiratory distress syndrome (ARDS) is characterized by alveolar-capillary barrier damage. Matrix metalloproteinases (MMPs) are implicated in the pathogenesis of ARDS. In the Beta Agonists in Acute Lung Injury Trial, intravenous salbutamol reduced extravascular lung water (EVLW) in patients with ARDS at day 4 but not inflammatory cytokines or neutrophil recruitment. We hypothesized that salbutamol reduces MMP activity in ARDS.

Methods: MMP-1/-2/-3/-7/-8/-9/-12/-13 was measured in supernatants of distal lung epithelial cells, type II alveolar cells, and bronchoalveolar lavage (BAL) fluid from patients in the Beta Agonists in Acute Lung Injury study by multiplex bead array and tissue inhibitors of metalloproteinases (TIMPs)-1/-2 by enzyme-linked immunosorbent assay. MMP-9 protein and activity levels were further measured by gelatin zymography and fluorokine assay.

Measurements and Main Results: BAL fluid MMP-1/-2/-3 declined by day 4, whereas total MMP-9 tended to increase. Unexpectedly, salbutamol augmented MMP-9 activity. Salbutamol induced 33.7- and 13.2-fold upregulation in total and lipocalin-associated MMP-9, respectively at day 4, compared with 2.0- and 1.3-fold increase in the placebo group, p < 0.03. Salbutamol did not affect BAL fluid TIMP-1/-2. Net active MMP-9 was higher in the salbutamol group (4222 pg/mL, interquartile range: 513-7551) at day 4 compared with placebo (151 pg/mL, 124-2108), p = 0.012. Subjects with an increase in BAL fluid MMP-9 during the 4-day period had lower EVLW measurements than those in whom MMP-9 fell (10 vs. 17 mL/kg, p = 0.004): change in lung water correlated inversely with change in MMP-9, r = -.54, p = 0.0296. Salbutamol up-regulated MMP-9 and down-regulated TIMP-1/-2 secretion in vitro by distal lung epithelial cells. Inhibition of MMP-9 activity in cultures of type II alveolar epithelial cells reduced wound healing.

Conclusions: Salbutamol specifically up-regulates MMP-9 in vitro and in vivo in patients with ARDS. Up-regulated MMP-9 is associated with a reduction in EVLW. MMP-9 activity is required for alveolar epithelial wound healing in vitro. Data suggest MMP-9 may have a previously unrecognized beneficial role in reducing pulmonary edema in ARDS by improving alveolar epithelial healing.

Doppler cooling of gallium atoms: 2. Simulation in complex multilevel systems

This paper derives a general procedure for the numerical solution of the Lindblad equations that govern the coherences arising from multicoloured light interacting with a multilevel system. A systematic approach to finding the conservative and dissipative terms is derived and applied to the laser cooling of p-block elements. An improved numerical method is developed to solve the time-dependent master equation and results are presented for transient cooling processes. The method is significantly more robust, efficient and accurate than the standard method and can be applied to a broad range of atomic and molecular systems. Radiation pressure forces and the formation of dynamic dark states are studied in the gallium isotope 66Ga.