Effect of heat wave on N2 fixation and N remobilisation of lentil (Lens culinaris MEDIK) grown under free air CO2 enrichment in a mediterranean-type environment

The stimulatory effect of elevated [CO₂ ] (e[CO₂ ]) on crop production in future climates is likely to be cancelled out by predicted increases in average temperatures. This effect may become stronger through more frequent and severe heat waves, which are predicted to increase in most climate change scenarios. Whilst the growth and yield response of some legumes grown under the interactive effect of e[CO₂ ] and heat waves has been studied, little is known about how N₂ fixation and overall N metabolism is affected by this combination. To address these knowledge gaps, two lentil genotypes were grown under ambient [CO₂ ] (a[CO₂ ], ~400 µmol·mol^-1 ) and e[CO₂ ] (~550 µmol·mol^-1 ) in the Australian Grains Free Air CO₂ Enrichment facility and exposed to a simulated heat wave (3-day periods of high temperatures ~40 °C) at flat pod stage. Nodulation and concentrations of water-soluble carbohydrates (WSC), total free amino acids, N and N₂ fixation were assessed following the imposition of the heat wave until crop maturity. Elevated [CO₂ ] stimulated N₂ fixation so that total N₂ fixation in e[CO₂ ]-grown plants was always higher than in a[CO₂ ], non-stressed control plants. Heat wave triggered a significant decrease in active nodules and WSC concentrations, but e[CO₂ ] had the opposite effect. Leaf N remobilization and grain N improved under interaction of e[CO₂ ] and heat wave. These results suggested that larger WSC pools and nodulation under e[CO₂ ] can support post-heat wave recovery of N₂ fixation. Elevated [CO₂ ]-induced accelerated leaf N remobilisation might contribute to restore grain N concentration following a heat wave.

Detection of nitrogen deficiency in wheat from spectral reflectance indices and basic crop eco-physiological concepts

We tested the capacity of several published multispectral indices to estimate the nitrogen nutrition of wheat canopies grown under different levels of water supply and plant density and derived a simple canopy reflectance index that is greatly independent of those factors. Planar domain geometry was used to account for mixed signals from the canopy and soil when the ground cover was low. A nitrogen stress index was developed, which adjusts shoot %N for plant biomass and area, thereby accounting for environmental conditions that affect growth, such as crop water status. The canopy chlorophyll content index (CCCi) and the modified spectral ratio planar index (mSRPi) could explain 68 and 69% of the observed variability in the nitrogen nutrition of the crop as early as Zadoks 33, irrespective of water status or ground cover. The CCCi was derived from the combination of 3 wavebands 670, 720 and 790 nm, and the mSRPi from 445, 705 and 750 nm, together with broader bands in the NIR and RED. The potential for their spatial application over large fields/paddocks is discussed.

Early defibrillation in out-of-hospital sudden cardiac death: an Australian experience

All patients with primary cardiac disease presenting with out-of-hospital sudden cardiac death (OH-SCD) to a provincial hospital were reviewed retrospectively over a 5-year period from 1985 to 1989. This coincided with the introduction of out-of-hospital defibrillation (OH-DEFIB) by ambulance officers. Of 215 patients, 17 (9%) survived to leave hospital alive, 15 of whom underwent OH-DEFIB. There was an increase in survivors from 4%, prior to OH-DEFIB, to 9% of all cardiac arrests, but this was not statistically significant (P = 0.3). However, long term survival amongst immediate survivors was associated with a statistically significant improvement following the introduction of OH-DEFIB (15 of 30 (50%) vs. 2 of 19 (10.5%), P < 0.01). Mean call-out, at-scene and transfer times did not significantly vary between survivors and non-survivors. A total of 155 (72%) had a known cardiac history, with the majority (74%) of arrests occurring at home. Of 134 witnessed arrests, only 46 (34%) underwent bystander-initiated cardiopulmonary resuscitation (CPR). A programme in CPR aimed at relatives of known cardiac patients, and the adoption of a paramedic protocol which improves oxygenation at the time of arrest are recommended.

Breeding-season habitat use by sticklebacks (Pisces: Gasterosteidae) at Isle Verte, Quebec

We examined habitat use patterns of three species of sticklebacks as they moved from the St. Lawrence estuary into tidal salt marsh pools to breed. All three species apparently avoided pools that dried out and settled more often in pools that retained their water. Habitat choice by immigrants was not influenced by either the presence of the most aggressive species or by resident fish density. Movements of fish into the marsh and densities of fish in the pools peaked on the first days of the approximately 7-day flooding cycles, and declined thereafter. Thus, large numbers of fish moved away from these pools after initially settling in them, but the reason for this and the subsequent fate of the fish is unknown.

The urgency distribution of an accident and emergency department's workload

The perceived urgency of 2000 consecutive patients attending the Accident and Emergency Department of the Royal Infirmary, Edinburgh, was assessed using a Linear Analogue Scale. Each patient was assessed by the receptionist, the receiving nurse and the treating doctor. The distribution of urgency rating produced for this patient group was shown to be comparable for each status of assessor, and to correlate with other outcome criteria such as admission and referral rates. The linear scale was also shown to correlate with retrospective assessment using a time-guided category scale. The accident and emergency department workload is predominantly of low urgency (90% less than 5 on a 0-10 scale). Older patients tend to have higher urgency ratings than younger patients and those referred by ambulance, either via general practitioner or 999 calls, have similarly higher urgency distributions. This study provides a basis for the development of a guided category scale for functional triage of accident and emergency departments. Other scoring systems have attempted to similarly quantify the medical component of the workload (Coira & Rothstein, 1983; Peel et al., 1962). However, the complexity of many of these scales, together with the difficulty in usage of so many different scales, begs a reappraisal of the overall triage of patients attending the emergency department. The aim of this study was to look at the perceived urgency distribution of patients presenting to the emergency department. We wished to compare the relative assessment of urgency by various levels of treating staff and to compare those assessments with the referral and outcome of these patients to provide the basis for the development of a comparative Triage Scale.

The effects of bird predation on an estuarine stickleback (Pisces: Gasterosteidae) community

Eight species of birds fed on a community of sticklebacks living in salt marsh pools along the southern shore of the St. Lawrence estuary in May and June when the fish breed. Three birds, the black-crowned night heron (Nycticorax nycticorax), the bronzed grackle (Quiscalus quiscula), and the ring-billed gull (Larus delawarensis) accounted for 80% of the estimated captures. Bird predation removed about 30% of the sticklebacks in the marsh. Significantly more male than female Gasterosteus aculeatus and G. wheatlandi were eaten, indicating selective predation is playing a role in structuring this fish community.