An 81-year-old woman underwent a colonoscopy because of a sigmoiditis poorly responding to conservative therapy. A rod-shaped foreign body found in the sigma proved impossible to remove conventionally. Irradiation with a low laser energy caused the foreign body to break apart, after which its extraction was straightforward. The further clinical course was uncomplicated. In this case a partial sigmoidectomy would have been indicated had the laser-supported extraction not been successful. The authors suggest that a similar procedure could be helpful in the management of foreign bodies in the esophagus.

Aged↗

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Attachment representation and cortisol response to the adult attachment interview in idiopathic spasmodic torticollis.

OBJECTIVE: The study investigates individual differences in the mental representation of attachment and their impact on the cortisol response to psychosocial stress in idiopathic spasmodic torticollis (IST). It was hypothesized (a) that in IST insecure attachment is more prevalent than in a non-clinical control group and (b) that subjects with dismissing attachment respond with higher physiological arousal to a specific stimulus activating the attachment behavioural system than subjects with secure attachment. METHOD: 20 patients with IST and 20 healthy controls matched for age and sex underwent the Adult Attachment Interview, an hour-long, semiclinical interview on attachment experiences. During the interview salivary cortisol levels were monitored. The subjects' mental state with regard to attachment was classified using the attachment Q-sort method. Anxiety and depression were measured as potential covariates of the adrenocortical stress response. RESULTS: Compared to the non-clinical group, dismissing attachment was strongly overrepresented in IST. In IST, but not in the healthy control group, dismissing attachment correlated with an elevated cortisol response to the interview. CONCLUSION: In clinical, but not in non-clinical samples dismissing attachment may be associated with increased vulnerability to psychosocial stress. The factors contributing to this interaction are not yet fully elucidated.

Adult↗

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[Dependence of the fish school movement and plankton special distribution on the phytoplankton growth rate].

In this paper we investigate the spontaneous emergence and the dynamics of patchiness in spatially distributed communities of plankton, which plays a key role in the matter rotation on earth. Patchiness is often supposed to be due to hydrodynamical factors (diffusion and advection). In contrast to this approach, we consider the formation of plankton patches as a result of interactions in the trophic chain nutrient--phytoplankton--zooplankton-fish. We present a mathematical model of such interactions, which combines a continuous description of the plankton spatio-temporal dynamics and a discrete description of the fish school movement. We show that the fish school can give rise to plankton patches. In turn, fish school walks are shown to depend on phytoplankton growth rate. We show also that the Hurst exponent characterizing the fish school movement in the diffusion approximation depends on phytoplankton growth rate.

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[The role of carnivorous zooplankton in dynamics of trophic interaction of fish and plankton].

A conceptual (minimal) model of the aquatic community is proposed, which includes phytoplankton, zooplankton, fish and fish larvae. It is shown that carnivorous zooplankton increases the system stability when the fish predation changes. As a result, the system collapse followed by algal bloom becomes less probable.

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[Interdependence of plankton spatial distribution and plancton biomass temporal oscillations: mathematical simulation].

The dynamics of aquatic biological communities in a patchy environment is of great interest in respect to interrelations between phenomena at various spatial and time scales. To study the complex plankton dynamics in relation to variations of such a biologically essential parameter as the fish predation rate, we use a simple reaction-diffusion model of trophic interactions between phytoplankton, zooplankton, and fish. We suggest that plankton is distributed between two habitats one of which is fish-free due to hydrological inhomogeneity, while the other is fish-populated. We show that temporal variations in the fish predation rate do not violate the strong correspondence between the character of spatial distribution of plankton and changes of plankton biomass in time: regular temporal oscillations of plankton biomass correspond to large-scale plankton patches, while chaotic oscillations correspond to small-scale plankton patterns. As in the case of the constant fish predation rate, the chaotic plankton dynamics is characterized by coexistence of the chaotic attractor and limit cycle.

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[Effect of the rate of phytoplankton growth on the spaced-time dynamics of plankton communities in an homogeneous environment].

We use a conceptual mathematical reaction-diffusion model to investigate the mechanisms of spatial structure formation and complex temporal dynamics of plankton in a heterogeneous environment. We take into account basic trophic interactions, namely, "prey-predator" interactions between phytoplankton, zooplankton, and fish in upper layers of natural waters. We consider plankton as a passive contaminant in turbulent waters. We show that plankton structure formation can result from the difference in phytoplankton growth rate in neighboring habitats. Phytoplankton and zooplankton biomass is shown to undergo both regular and chaotic oscillations. The fish predation rate substantially affects the spatial and temporal dynamics of plankton in a heterogeneous environment.

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[Evolution of rotifer population dynamics in a heterogeneous habitat: mathematical modeling].

We present the results of mathematical modeling of a rotifer species inhabiting two coupled habitats with different environmental conditions. We use the modified Consensus model and show that the exchange between the habitats can lead to chaotization of originally regular plankton dynamics and synchronization of plankton biomass oscillations. As a result, the invasion of a chaotic regime takes place.

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