1,037 research outputs found

    A discrete slug population model determined by egg production

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    Slugs are significant pests in agriculture (as well as a nuisance to gardeners), and it is therefore important to understand their population dynamics for the construction of efficient and effective control measures. Differential equation models of slug populations require the inclusion of large (variable) temporal delays, and strong seasonal forcing results in a non-autonomous system. This renders such models open to only a limited amount of rigorous analysis. In this paper, we derive a novel batch model based purely upon the quantity of eggs produced at different times of the year. This model is open to considerable reduction; from the resulting two variable discrete-time system it is possible to reconstruct the dynamics of the full population across the year and give conditions for extinction or global stability and persistence. Furthermore, the steady state temporal population distribution displays qualitatively different behavior with only small changes in the survival probability of slugs. The model demonstrates how small variations in the favorability of different years may result in widely different slug population fluctuations between consecutive years, and is in good agreement with field data

    ROLE OF INTERFERONS IN REGULATION OF OSTOGENIC AND OSTEORESORPTIVE PROCESSES

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    Bone tissue preserves high metabolic activity during all time of its life. Homeostasis of bone tissue is provided by fine balance between its formation by osteoblasts and its resorption by osteoclasts. There are complex regulatory interrelations between cells of bone differon and. system of interferons, the peculiarities of production of which mediate disturbances of osteoformating and. resorptive components of osteo metabolism at various pathological conditions. The review presents literature data on the role of interferons in regulation of osteogenous and. osteoresorptive processes which opens up the prospective of aimed application of interferons preparations with the purpose of restoration of immunologic imbalance and. bone tissue homeostasis

    Complications at the hip replacement and ways of their prediction (review of literature)

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    The review presents modern data on the role of immune system in development of postoperative complications at hip replacement. Surgical stress while having depressive influence on immune system is powerful factor that causes conditions for development of secondary immune depression or intensifies it. On this background possibility of development of both early and late postoperative complications is quite high, that's why frequency of revision hip replacement increases steadily. Providing of stability of endoprosthesis is extremely important at total hip replacement. Researches realized during last decades determined connection of processes of osteogenesis and bone resorption and polypeptide factors of growth - cytokines. That's why questions of prevention and. correction of loss of bone substance with use of modern pharmacological preparations are important in the movement of observed problem. Infectious complications are also very significant ones at hip replacement. The fact of infectious process being the result of interrelation of macro- and. microorganisms and. immune system having one the leading roles in this process is doubtless. Among all the measures for prevention of postoperative complications their prevention that allows to determine right tactics of operative treatment, to realize complex of preparatory and. rehabilitation measures and. to improve the results of treatment and quality of life of patient, becomes important. Use of immunologic methods allowed to choose criteria and to develop ways of prevention of development of complications at hip replacement. However proposed ways not always allow to count individual susceptibility of an organism to different infectious pathogens; most of them are based on the determination of various specific and. quite laborious indices. Necessity of realization of researches before an operation and. in different terms of postoperative period for determination of dynamic dependence of changes of laboratory indices is significant disadvantage and requires quite prolonged observation of the patient for getting an information about prevention of hip replacement results. That's why further development and use of new ways of early hip replacement undoubtedly allows to improve results of surgical treatment of patients with different forms of coxarthrosis

    One-Dimensional Discrete Stark Hamiltonian and Resonance Scattering by Impurities

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    A one-dimensional discrete Stark Hamiltonian with a continuous electric field is constructed by extension theory methods. In absence of the impurities the model is proved to be exactly solvable, the spectrum is shown to be simple, continuous, filling the real axis; the eigenfunctions, the resolvent and the spectral measure are constructed explicitly. For this (unperturbed) system the resonance spectrum is shown to be empty. The model considering impurity in a single node is also constructed using the operator extension theory methods. The spectral analysis is performed and the dispersion equation for the resolvent singularities is obtained. The resonance spectrum is shown to contain infinite discrete set of resonances. One-to-one correspondence of the constructed Hamiltonian to some Lee-Friedrichs model is established.Comment: 20 pages, Latex, no figure

    Dressing chain for the acoustic spectral problem

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    The iterations are studied of the Darboux transformation for the generalized Schroedinger operator. The applications to the Dym and Camassa-Holm equations are considered.Comment: 16 pages, 6 eps figure

    Benzo‐extended cyclohepta[def]fluorene derivatives with very low‐lying triplet states

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    Open-shell non-alternant polycyclic hydrocarbons (PHs) are attracting increasing attention due to their promising applications in organic spintronics and quantum computing. Herein we report the synthesis of three cyclohepta[def]fluorene-based diradicaloids (1–3), by fusion of benzo rings on its periphery for the thermodynamic stabilization, as evidenced by multiple characterization techniques. Remarkably, all of them display a very narrow optical energy gap (Egopt=0.52–0.69 eV) and persistent stability under ambient conditions (t1/2=11.7–33.3 h). More importantly, this new type of diradicaloids possess a low-lying triplet state with an extremely small singlet–triplet energy gap, as low as 0.002 kcal mol−1, with a clear dependence on the molecular size. This family of compounds thus offers a new route to create non-alternant open-shell PHs with high-spin ground states, and opens up novel possibilities and insights into understanding the structure–property relationships

    Mediator of DNA Damage Checkpoint 1 (MDC1) Contributes to High NaCl-Induced Activation of the Osmoprotective Transcription Factor TonEBP/OREBP

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    Background: Hypertonicity, such as induced by high NaCl, increases the activity of the transcription factor TonEBP/OREBP whose target genes increase osmoprotective organic osmolytes and heat shock proteins. Methodology: We used mass spectrometry to analyze proteins that coimmunoprecipitate with TonEBP/OREBP in order to identify ones that might contribute to its high NaCl-induced activation. Principal Findings: We identified 20 unique peptides from Mediator of DNA Damage Checkpoint 1 (MDC1) with high probability. The identification was confirmed by Western analysis. We used small interfering RNA knockdown of MDC1 to characterize its osmotic function. Knocking down MDC1 reduces high NaCl-induced increases in TonEBP/OREBP transcriptional and transactivating activity, but has no significant effect on its nuclear localization. We confirm six previously known phosphorylation sites in MDC1, but do not find evidence that high NaCl increases phosphorylation of MDC1. It is suggestive that MDC1 acts as a DNA damage response protein since hypertonicity reversibly increases DNA breaks, and other DNA damage response proteins, like ATM, also associate with TonEBP/OREBP and contribute to its activation by hypertonicity. Conclusions/Significance: MDC1 associates with TonEBP/OREBP and contributes to high NaCl-induced increase of tha

    BARIATRIC SURGERIES AND CORRECTION OF METABOLIC DISORDERS IN PATIENTS WITH MORBID OBESITY

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    The article presents the results of bariatric surgeries carried out in the clinic in patients with morbid obesity. We traced both the nearest and remote results after treatment, the loss of body weight in dynamics, relief of the manifestations of "metabolic syndrome" as well as we estimated the quality of life of patients in pre-and postoperative period

    Measurements of integral muon intensity at large zenith angles

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    High-statistics data on near-horizontal muons collected with Russian-Italian coordinate detector DECOR are analyzed. Precise measurements of muon angular distributions in zenith angle interval from 60 to 90 degrees have been performed. In total, more than 20 million muons are selected. Dependences of the absolute integral muon intensity on zenith angle for several threshold energies ranging from 1.7 GeV to 7.2 GeV are derived. Results for this region of zenith angles and threshold energies have been obtained for the first time. The dependence of integral intensity on zenith angle and threshold energy is well fitted by a simple analytical formula.Comment: 4 pages, 4 figures, 1 tabl
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