Deterministic preparation of a tunable few-fermion system

Systems consisting of few interacting fermions are the building blocks of matter, with atoms and nuclei being the most prominent examples. We have created a few-body quantum system with complete control over its quantum state using ultracold fermionic atoms in an optical dipole trap. Ground-state systems consisting of 1 to 10 particles are prepared with fidelities of ～90%. We can tune the interparticle interactions to arbitrary values using a Feshbach resonance and have observed the interaction-induced energy shift for a pair of repulsively interacting atoms. This work is expected to enable quantum simulation of strongly correlated few-body systems.     

A slowly progressive retinopathy in the Shetland Sheepdog

Objective To describe a slowly progressive retinopathy (SPR) in Shetland Sheepdogs. Animals Forty adult Shetlands Sheepdogs with ophthalmoscopic signs of SPR and six normal Shetland Sheepdogs were included in the study. Procedure Ophthalmic examination including slit‐lamp biomicroscopy and ophthalmoscopy was performed in all dogs. Electroretinograms and obstacle course‐test were performed in 13 affected and 6 normal dogs. The SPR dogs were subdivided into two groups according to their dark‐adapted b‐wave amplitudes. SPR1‐dogs had ophthalmoscopic signs of SPR, but normal dark‐adapted b‐wave amplitudes. Dogs with both ophthalmoscopic signs and subnormal, dark‐adapted b‐wave amplitudes were assigned to group SPR2. Eyes from two SPR2 dogs were obtained for microscopic examination. Results The ophthalmoscopic changes included bilateral, symmetrical, greyish discoloration in the peripheral tapetal fundus with normal or marginally attenuated vessels. Repeated examination showed that the ophthalmoscopic changes slowly spread across the central parts of the tapetal fundus, but did not progress to obvious neuroretinal thinning presenting as tapetal hyper‐reflectivity. The dogs did not appear seriously visually impaired. SPR2 showed significantly reduced b‐wave amplitudes throughout dark‐adaptation. Microscopy showed thinning of the outer nuclear layer and abnormal appearance of rod and cone outer segments. Testing for the progressive rod–cone degeneration ( prcd )‐mutation in three dogs with SPR was negative. Conclusion Slowly progressive retinopathy is a generalized rod–cone degeneration that on ophthalmoscopy looks similar to early stages of progressive retinal atrophy. The ophthalmoscopic findings are slowly progressive without tapetal hyper‐reflectivity. Visual impairment is not obvious and the electroretinogram is more subtly altered than in progressive retinal atrophy. The etiology remains unclear. SPR is not caused by the prcd‐mutation.     

In Situ Avoidance Response Of Adult Atlantic Salmon To Waste From The Wood Pulp Industry

An accidental release of non-toxic waste from decommissioned wood pulp industry in the River Numedalslågen, Southern Norway, occurred in the upper part of the accessible stretches for anadromous fish during a study of migration behaviour of radio tagged Atlantic salmon (Salmo salar, n=32, body length 51–99 cm). The fish had completed the migration phase and initiated the resident phase characterised by little movement until spawning. When the wooden fibres and pulp were released, 16 of 32 (50%) salmon showed an immediate avoidance response. Six (19%) salmon moved upstream and 10 (31%) salmon moved downstream. Of the salmon moving downstream, eight (25%) moved all the way to sea (average 14.8 km). Four re-entered the River Numedalslågen, two entered a neighbouring river and two were not recorded later. Fish moving downstream but without moving to the sea, moved on average 5.3 km during the episode, whereas those moving upstream moved on average 6.7 km. All fish recorded after the episode (n=30) survived until the spawning season. The study demonstrates that fish in nature may show an evident avoidance response, even to non-toxic contaminants. For Atlantic salmon, the size of the spawning population may be reduced by fish leaving the river (13% left the river and never came back). Moreover, the dispersal of salmon to other rivers may increase, and the distribution of the spawning population within the contaminated river may shift.     

A method for determining Michaelis-Menten kinetic parameters of nutrient uptake for plants growing in soil

The relationship between nutrient influx (I_n) and solution concentration at the root surface (C_lo) has not yet been determined for roots growing in soil because of difficulties in measuring C_lo. Corn was grown on two soils with 12 and 21% clay. Each soil had five K levels ranging from low to very high. Potassium influx (I_n) was determined from K uptake between two harvests and root length. C_lo was then calculated from the average soil solution concentration and I_n by assuming that diffusion is the main transport mechanism for K to the root. Potassium influx plotted against C_lo showed a saturation curve, typical of a Michaelis-Menten kinetic relationship. The Michaelis-Menten uptake parameters, maximum influx (I_max) and Michaelis constant (K_m), were obtained by the “Hanes” plot. There was close agreement, without lack of fit, between calculated and observed data. The proposed procedure therefore appears to be suitable for estimating the uptake kinetics of roots growing in soil. Requirements for applications of the method are discussed.     

Reduction of decomposition rates of scots pine needle litter due to heavy-metal pollution

Decomposition of unpolluted Scots pine needle litter was studied in two heavy-metal-pollution gradients in Sweden; one near a brass mill and the other around a primary smelter. In the latter area locally collected polluted Scots pine needle litter was also incubated. Decomposition rates were strongly influenced by the metal pollution and a decrease in the rate of mass-loss occurred. In the brass-mill gradient this occurred until about 1 km from the pollution source which corresponded to about 500 µg Cu and 1 000 µg Zn g^?1 soil. Data are presented to indicate that lignin decomposition was more sensitive to pollution than decomposition of whole litter and affected further away from the pollution sources. At the smelter sites, the metal-polluted needle litter decomposed more slowly than the unpolluted needle litter, and this difference was enhanced close to the smelter. The results indicate that heavy metals accumulated in needles prior to shedding have a long-term impact on the subsequent decomposition of the litter. Both litter quality and soil factors thus contribute to the reduced litter decomposition rate in metal-polluted forests. A new non-linear model with decreasing decay rate was used in the statistical evaluation. The model can be used to characterize the effects of pollution on decomposition rate.     

Antioxidants, low molecular weight carbohydrates, and total antioxidant capacity in strawberries (Fragaria x ananassa): effects of cultivar, ripening, and storage

Four cultivars of strawberries (Senga Sengana, BFr77111, Elsanta, and Honeoye) were studied for their content of antioxidants, total antioxidant capacity, and low molecular weight carbohydrates in relation to harvest year, ripening stage, and cold storage. For ascorbic acid, chlorogenic acid, ellagic acid, and total antioxidative capacity, measured in both water-soluble and water-insoluble extracts, there was a 2-5-fold variation among cultivars. Unripe berries contained lower concentrations of chlorogenic acid and p-coumaric acid and also quercetin and kaempferol compared with riper berries. During cold storage for up to 3 days, relatively few changes in the concentration of the different antioxidants occurred. The concentrations of several investigated parameters were interrelated, for example, for ascorbic acid and water-soluble antioxidant capacity and for ellagic acid and water-insoluble antioxidant capacity. The dominating sugars in strawberries were fructose and glucose, but considerable amounts of sucrose were also present, and their contents varied among cultivars, giving a predicted glycemic index of approximately 81. Verbascose, raffinose, and stachyose were found in only minor amounts. The study shows that the concentration of a number of bioactive compounds in strawberries varied according to cultivar, ripening stage, and storage. This information should make it possible to select strawberries with an optimal content of bioactive compounds.     

The Nutritive Value For Growing Pigs of Single Cell Protein (Saccharomyces Cerevisiae) Produced from Sulphite Spent Liquor

The effects on growing pigs of substituting 4.5 and 9 % of soy bean meal with a corresponding amount of single cell protein produced from sulphite spent liquor in a diet based on cereals and fish meal have been studied. The concentration of lignosulphonic acids in the single cell protein product was found to be 0.6 % ± 0.2 % (m. ± s). No differences in the weight gain, feed conversion ratio or fat thickness of the pigs, as compared with the controls, were observed when fed single cell protein-containing diets from about 29 to 80 kg in the course of 11 weeks. Nor were any effects found on addition of 0.15 % of methionine to the diets.     

Effect of plant density in coupled aquaponics on the welfare status of African catfish,Clarias gariepinus

We investigated the effects of plant density on the welfare of African catfish, Clarias gariepinus, in coupled aquaponics over 85 days. The moderate density (mpd) of basil, Ocimum basilicum, was compared with the high density (hpd) and control (n = 0). The behavior was analyzed by visual and video observations, and after the application of induced stressors, skin injuries, blood glucose, lactate, and plasma cortisol responses were considered. The hpd fish showed the least activity (control: visual 77.8%, video 81.6%; mpd: 74.6%, 82.6%; hpd: 63.2% [p < 0.05], 78.8%). High agonistic behavior (control: 5, 131; mpd: 4, 57; hpd: 1, 45) and the highest number of injuries (control: 3.9; mpd: 2.9; hpd: 3.4) were observed in the control. Glucose and lactate levels did not differ significantly (control: 5.5, 2.6 mmol/L; mpd: 5.6, 2.7 mmol/L; hpd: 5.3, 2.6 mmol/L); however, cortisol levels did (control: 18.8 ng/mL, mpd: 19.9 ng/mL, hpd: 25.8 ng/mL). pH adjustment led to additional stress, resulting in temporal cortisol alterations. While in the control and mpd, low cortisol levels were followed by acute responses and downregulation, the hpd fish showed prior elevation and lagged an acute response. However, comparing injuries and behavioral patterns with control, aquaponics with high basil density influenced African catfish positively.     

Laboratory and field investigations of salmon lice [Lepeophtheirus salmonis (Krøyer)] infestation on Atlantic salmon (Salmo salar L.) post-smolts

Hatchery‐reared 1‐year‐old Atlantic salmon post‐smolts (Salmo salar L.), artificially infected with salmon lice [Lepeophtheirus salmonis (Krøyer)] copepodids, were found to suffer from primary alterations (increased cortisol levels) at early lice stages. Secondary alterations, such as osmotic stress (increased chloride levels), first occurred after the preadult stages of the lice appeared. Fish with the highest salmon lice infections died throughout the experiment. Seven years of field investigation of Trondheimsfjorden showed that Atlantic salmon post‐smolts descending coastal waters can become heavily infected with salmon lice. The migrating post‐smolts were only infected with the chalimus stages, showing that the fish had only recently left the rivers. The infection level, however, varied considerably between the years, and, in 1998, the infection was higher than previous years. The experimental results have been combined with the field data to appraise the consequences of the infection.     

Atelectasis causes gas exchange impairment in the anaesthetised horse

The anatomical basis of gas exchange impairment in the anaesthetised horse was studied by computerised tomography (CT; three shetland ponies) and morphological analysis (one pony and three horses). By means of CT, densities were seen in dependent lung regions early during anaesthesia, both with spontaneous breathing and with mechanical ventilation. The densities remained for some time where they had initially been created when the animal was turned from dorsal to sternal recumbency. Deep insufflation of the lungs reduced the dense area. Gas exchange was impaired roughly in proportion to the dense area. On histological analysis, the densities were atelectatic and congested with blood. Gravimetry showed no more extravascular water per unit lung tissue in the atelectatic than in the 'normal' regions, and the blood content was increased only slightly. It is concluded that the horse develops atelectasis in dependent lung regions early during anaesthesia in dorsal recumbency, and that atelectasis is the most likely explanation for the large shunt and impaired arterial oxygenation regularly seen during anaesthesia.