Antenna pattern comparison between an outdoor cylindrical near-field test facility and an indoor spherical near-field antenna test facility

A new spherical near-field probe-positioning device has been designed and constructed, consisting of a large 5.0 meter fixed arc. This arc has been installed in a near-field test facility, located at Alenia Marconi Systems, on the Isle of Wight, UK. As part of the near-field qualification, testing was performed on a ground-based radar antenna. The resultant patterns were compared against measurements collected on the same antenna on a large outdoor cylindrical near-field test facility, also located on the Isle of Wight [F. Steiner et al., Jan. 1994]. These measurements included multiple-frequency measurements and multiple pattern comparisons. This paper summarizes the results obtained as part of the measurement program, and includes discussions on the error budgets for the two ranges, along with a discussion of the mutual error budget between the two ranges.     

Treatment with anti-granulocyte antibodies inhibits the effector phase of experimental autoimmune encephalomyelitis

Emerging data suggest that polymorphonuclear leukocytes (PMNLs) can play an important role in Ag-dependent immune responses. Therefore, we have assessed the involvement of these cells in the development of an organ-specific autoimmune disease, experimental autoimmune encephalomyelitis (EAE), in the mouse. Depletion of peripheral blood PMNLs beginning day 8 after immunization significantly delayed and in some cases totally prevented the development of clinical EAE in mice. Depletion of PMNLs beginning 1 day before sensitization and continuing until day 7 postimmunization had no effect on the subsequent development of EAE, suggesting that depletion alters the efferent but not the afferent arm of the immune response. In vitro studies showed that lymphoid cells from mice protected from EAE by PMNL depletion beginning on day 8 postsensitization proliferated in response to specific Ag to a level equal to cells from sensitized animals treated with control serum, again indicating that treatment was not affecting the afferent limb of the immune response. Further evidence that PMNL may be necessary in initiating the pathology of EAE was seen in passive transfer experiments where PMNL-depleted recipients of MBP-specific lymphoid effector cells developed EAE much less effectively than did animals treated with control Ab. Taken together, these data indicate that PMNLs play a critical role in the effector phase of the development of the clinicopathologic expression of EAE in mice.     

Remote optical detection of biomass burning using a potassium emission signature

A remotely detectable signature for biomass burning that is specific to flaming combustion is found in the strong emission lines of potassium (K) at 766.5 nm and 769.9 nm. Ground level spectra of a test fire illustrate the high contrast signal provided by K emission. Image data collected at high altitude using the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) sensor and analysed for K emission vividly displays the fire fronts of a 1995 fire in Brazil. Sensors for K emission can use silicon detector technology for advantages in high sensitivity, low cost, wide area coverage and fine spatial resolution.     

Public perceptions of river corridors and attitudes towards river works

The Environment Agency has accepted the need for public participation in decisions concerning river management in keeping with Agenda 21 concerns for environmental policies that command a good measure of public support. In the past, public participation has often relied upon consultations involving formal meetings with interest groups and local politicians. Methods of public consultation are changing. In tapping public opinion the Environment Agency now relies less on public meetings and increasingly more on a direct approach and involvement of the public. Research at Middlesex University is part of the attempt to provide opportunities for the representation of views of the lay public to be considered within the management of rivers and river corridors. The research has used surveys of representative samples of members of the public, often at riverside sites. This paper reports on some of the research projects that have developed on these themes, and analyses the implications of their results for river management and the protection of nature conservation values.     

Timing and severity of immunizing diseases in rabbits is controlled by seasonal matching of host and pathogen dynamics

Infectious diseases can exert a strong influence on the dynamics of host populations, but it remains unclear why such disease-mediated control only occurs under particular environmental conditions. We used 16 years of detailed field data on invasive European rabbits (Oryctolagus cuniculus) in Australia, linked to individual-based stochastic models and Bayesian approximations, to test whether (i) mortality associated with rabbit haemorrhagic disease (RHD) is driven primarily by seasonal matches/mismatches between demographic rates and epidemiological dynamics and (ii) delayed infection (arising from insusceptibility and maternal antibodies in juveniles) are important factors in determining disease severity and local population persistence of rabbits. We found that both the timing of reproduction and exposure to viruses drove recurrent seasonal epidemics of RHD. Protection conferred by insusceptibility and maternal antibodies controlled seasonal disease outbreaks by delaying infection; this could have also allowed escape from disease. The persistence of local populations was a stochastic outcome of recovery rates from both RHD and myxomatosis. If susceptibility to RHD is delayed, myxomatosis will have a pronounced effect on population extirpation when the two viruses coexist. This has important implications for wildlife management, because it is likely that such seasonal interplay and disease dynamics has a strong effect on long-term population viability for many species.     

Simultaneous bilateral tibial stress fractures in a 15-year-old milkman--a case report

Although stress fractures are well recognized, their frequency, sequelae and complex aetiology are often under-rated. In this case report, we describe an unusual case of simultaneous bilateral stress fractures of the proximal tibial shaft in a young man, exposed to a sudden increase in unaccustomed joint loading due to his part-time occupation. The pathogenesis is discussed.     

Ehrlichiosis: findings on chest radiographs in three pediatric patients

OBJECTIVES: Ehrlichiosis is a newly recognized tick-borne infection affecting both children and adults. The disease is usually mild, with flulike symptoms, but can be fatal. We present the chest radiographs and, in one case, the chest CT scan of all recognized pediatric cases of ehrlichiosis to date from our institution. CONCLUSION: Ehrlichiosis should be included in the differential diagnosis of acutely ill pediatric patients with a history of possible tick exposure and radiographic patterns of interstitial prominence, alveolar opacities, or consolidation that may be associated with pleural effusion.