Flatband slow light in photonic crystals featuring spatial pulse compression and terahertz bandwidth.

Paradoxically, slow light promises to increase the speed of telecommunications in novel photonic structures, such as coupled resonators [1] and photonic crystals [2,3]. Apart from signal delays, the key consequence of slowing light down is the enhancement of light-matter interactions. Linear effects such as refractive index modulation scale linearly with slowdown in photonic crystals [3], and nonlinear effects are expected to scale with its square [4]. By directly observing the spatial compression of an optical pulse, by factor 25, we confirm the mechanism underlying this square scaling law. The key advantage of photonic structures over other slow light concepts is the potentially large bandwidth, which is crucial for telecommunications [5]. Nevertheless, the slow light previously observed in photonic crystals [2,3,6,7] has been very dispersive and featured narrow bandwidth. We demonstrate slow light with a bandwidth of 2.5 THz and a delay-bandwidth product of 30, which is an order of magnitude larger than any reported so far.

Coupled photonic crystal heterostructure nanocavities.

We show the first experimental demonstration of multiple heterostructure photonic crystal cavities being coupled together to form a chain of coupled resonators with up to ten cavities. This system allows us to engineer the group velocity of light over a wide range. Devices were fabricated using 193 nm deep UV lithography and standard silicon processing technology. Structures were analysed using both coupled resonator and photonic bandstructure theory, and we highlight the discrepancies arising from subtle imperfections of the fabricated structure.

A common dementia in a rare disease.

The patient described was a 68-year-old man presenting with a severe, subacute depressive state with rapid decline in memory, psychomotor retardation and refusal to eat, who was referred by the medical team for ECT. His memory impairment could not be explained within the context of his depressed mood and he was eventually found to have a primary cerebral lymphoma of the non-Hodgkin's type. He died 10 weeks after initial psychiatric assessment.

The acute effect of intravenously administered recombinant human erythropoietin on the immune response of uremic patients maintained on regular hemodialysis.

The uremic patient on regular hemodialysis (RHD) is subjected to a wide range of immune modulators including the uremic state per se, multiple transfusions and exposure to bioincompatible materials and endotoxins. Erythropoietin (EPO) therapy may raise concern about its potential influence on this complex scenario. To envisage this issue, 15 adequately selected patients, stable on RHD, were randomly assigned in a 2:1 ratio into EPO and placebo groups. After initial assessment and determination of baseline values, they received, in a double-blind manner, either EPO or normal saline as an intravenous bolus immediately after termination of dialysis for 30 successive sessions. Thirty minutes later, following sessions 1, 10, 20, and 30, samples were obtained for determination of blood counts, red cell indices, peripheral lymphocyte counts (PLC), CD4/CD8 ratios, blood EPO levels, and serum concentrations of interleukins (IL) IL-2r, IL-3, and IL-6, tumor necrosis factor (TNFs and TNFalpha), and neopterin (NPT). Blood EPO levels displayed the predicted rise in the EPO group, which correlated with partial improvement of red cell parameters. The mean total leukocyte count and PLCs was significantly increased in the EPO group (p < 0.05) but not in the placebo group. CD4/CD8 ratios were not significantly changed in either group. The serum concentrations of IL-2r, IL-3, and NPT remained fairly stable while that of IL-6 was widely variable in both study groups. The mean serum concentrations of TNF and particularly TNFalpha showed a steady and statistically significant increment in the EPO group from 6 to 41 pg/ml (p < 0.05) and 93 to 128 pg/ml (p < 0.03), respectively. No significant change was noticed in the control group. It is concluded that intravenous administration of EPO under the conditions of this study may have an immune stimulating effect. This is shown by the release of TNFs, which in turn may be responsible, through different potential mechanisms, for the increase in the mean peripheral neutrophil count and the blunting of erythroid responsiveness to EPO therapy.

A survey of emergency medical care at Uluru (Ayers Rock).

OBJECTIVES: To determine the emergency practice profile of the Ayers Rock population and the health risk of tourist activities. DESIGN AND PARTICIPANTS: A prospective survey of all patients presenting to the medical staff at Ayers Rock Medical Centre between 1 July 1991 and 31 December 1992. MAIN OUTCOME MEASURE: A serious incident was defined as an incident that was life threatening or required more than 1.5 hours of emergency medical attention. RESULTS: There were 255 serious incidents, 40 of which were immediately life threatening and six of which resulted in death. Most serious incidents were not associated with climbing Uluru, but nine of 13 myocardial infarcts occurred on the Rock, all involving tourists (P < 0.001). CONCLUSIONS: Living in or visiting the Ayers Rock area is associated with an increased health risk and the Uluru climb is associated with a high incidence of myocardial infarction. The emergency practice workload is higher than at other comparable rural facilities.

Emergency preparedness - the missing factor in risk assessment

Starting from news reports of a highly publicized dangerous goods incident this paper examines the paradox where a community is aware and alarmed that it is faced by an existing and continuing hazard, yet concentrates on a strategy of seeking ultimate removal of the source of the hazard while doing nothing to prepare for the emergency if one arises in the meantime. This paper suggests that, to overcome this, such studies must place greater emphasis on the effect of preparedness and response in mitigating the potential damage that may result from an emergency, and indicates how this effects can be quantified for use in risk analysis models.(AU)