668 research outputs found

    Сезонна динаміка угруповань прибережного зоопланктону річки Удай у межах Національного природного парку «Пирятинський»

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    The increase in anthropogenic impact on aquatic ecosystems causes significant alterations in the composition and structure of hydrobiont groups. These processes are characteristic of the hydrobiocenoses of the Uday River, the valley of which lies within the National Nature Park "Pyryatynsky", established in 2009 in the Pyryatyn district of Poltava region. Within this protected area it is convenient to carry out continuous monitoring of changes in anthropogenic load on shore ecosystems of the river. One of the most convenient monitoring groups is zooplankton, which is one of the essential components of the trophic networks of aquatic ecosystems and which is the feeding basis of planktonophagous and young fish. The object of this research was the major groups of zooplankton: rotifers (class Eurotatoria), cladocerans (class Branchiopoda, order Cladocera), different age stages of copepods (class Copepoda), ostracods (class Ostracoda). Zooplankton were collected in the daytime in spring (mid April), summer (end of July) and autumn (late September) 2016 within eight research stations. As a result of the conducted research, 69 species of zooplankton were registered within the littoral water area of the Uday River. Monogonont rotifers numbered 19 (27.5%) species, bdelloid rotifers (subclass Bdelloidea), cladocerans – 33 (47.9%) species, copepods – 17 (24.6%). According to the faunal spectrum in the zooplankton groups, representatives of the cladoceran complex predominated. This is due to the favourable conditions for the development of filtrators, of which a considerable part is cladocerans. Three species of rotifers were identified in Poltava region for the first time: Beauchampiella eudactylota (Gosse, 1886), Dipleuchlanis propatula (Gosse, 1886), Mytilina acanthophora (Hauer, 1938). During the spring, 33 species of zooplankton were collected: rotifers – 10 species, cladocerans – 14, copepods – 9 species. In summer 41 species were registered, including rotifers – 10, cladocerans – 18, and copepods – 13. In autumn 37 species were found: 6 species of rotifers, cladocerans – 21 and copepods – 10. The species composition of the zooplankton in different seasons had a low similarity, as evidenced by Jaccard index: spring and autumn (J = 25.4), spring and autumn (J = 34.5), and summer and autumn (J = 34.6). In the spring, pelagic (36.3%) and phytophilic (45.6%) groups prevailed, and phytophilic dominated in summer (41.4%) and autumn (48.7%). Of the various groups classified according to feeding type, representatives of the peaceful group dominated in all the studied seasons, in spring comprising 69.7%, in summer – 65.8%, and in autumn – 73%. The density and biomass of zooplankton of the Uday River were “low” in spring and summer, and "very low" – in autumn. Наведено результати аналізу сезонної динаміки угруповань зоопланктону річки Удай в межах Національного природного парку «Пирятинський» за 2016 рік. Видове багатство у межах восьми дослідних станцій представлене 69 видами моногононтних коловерток, гіллястовусих і веслоногих ракоподібних. Уперше для Полтавської області визначено три види коловерток: Beauchampiellaeudactylota (Gosse, 1886), Dipleuchlanispropatula (Gosse, 1886), MytilinaacanthophoraHauer, 1938. Максимальне видове багатство (41 вид) зареєстровано влітку, що пов’язано з бурхливим розвитком макрофітів (і оптимальною для них температурою). Протягом трьох сезонів за фауністичним спектром в угрупованнях зоопланктону переважали представники кладоцерного комплексу. Виявлено невисокі значення індексу видової схожості Жаккара для різносезонних угруповань зоопланктону: J = 25,4–34,6. Проаналізовано сезонні зміни основних екологічних показників угруповань зоопланктону: екологічний спектр, тип живлення, щільність, біомаса. В угрупованнях зоопланктону протягом року відбулася зміна домінантної пелагічної групи на фітофільну. Для таких водойм, як річка Удай, класичним виявився трофічний спектр угруповань зоопланктону, представлений трьома групами, значний відсоток з яких склали мирні представники: весна – 69,7%, літо – 65,8%, осінь – 73,0%. Навесні в межах зарослого біотопу та на чистоводді відмічено найвищі показники щільності та біомаси.

    Morphologically disordered pore model for characterization of micro-mesoporous carbons

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    We present a new morphologically disordered slit-shaped pore (MDSP) model for simulating gas adsorption in micro-mesoporous carbonaceous materials. The MDSP model qualitatively accounts for the inherent roughness of carbon pore walls in accord with the atomistic structural model of LMA10 reference carbon material. The MDSP model is applied to pore size distribution (PSD) calculations from nitrogen adsorption isotherms measured at 77.4 K in the range of pore widths from 0.72 to 40 nm. The MDSP model improves significantly the nitrogen adsorption porosimetry and, being fully atomistic, it is transferable to study various adsorbate-adsorbent systems. Computations of PSD functions for a series of carbonaceous materials, including activated carbon fiber, granular activated carbons, synthetic activated carbons showed that MDSP generates smooth Gaussian-type PSD functions with a well-defined average pore size. Furthermore, PSD functions computed from the MDSP model are free from the artificial gaps in the region of narrow micropores (∼1 nm and ∼2 nm) predicted from the standard slit-shaped pore models with ideal graphite-like walls. MDSP is not only a complementary model to existing approaches, such as quench-solid density functional theory method, but it paves the way to efficient atomistic simulations of various compounds within morphologically disordered carbon nanopores

    Characterization of a 5 mm thick CZT-Timepix3 pixel detector for energy-dispersive γ -ray and particle tracking

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    The present manuscript describes a comprehensive characterization of a novel highly segmented 5 mm CZT sensor attached to Timepix3. First, the sensor’s IV curve was measured and basic sensor characterization was done with laboratory γ-radiation sources. The sensor resistivity was determined to be (0.155± 0.02) GOhm · cm. The sensor showed decent homogeneity, both for the per-pixel count rate and electron mobility-lifetime product μ e τ e. The latter was measured to be μeτe¯ = 1.3 × 10−3 cm2/V with a standard deviation σ = 0.4 × 10−3 cm2/V describing the dispersion of values for different pixels. The basic sensor characterization is complemented by measurements at grazing angle in a 120 GeV/c at the CERN’s Super Proton Synchrotron. The penetrating nature of these particles together with the pixelation of the sensor allows for a determination of the charge collection efficiency (CCE), as well as charge carrier drift properties (drift times, lateral charge cloud expansion) as a function of the interaction depths in the sensor. While CCE drops by 30%–40% towards the cathode side of the sensor, from the drift time dependency on interaction depth, the electron mobility μ e was extracted to be (944.8 ± 1.3) cm2/V/s and τ e = (1.38 ± 0.31) μs. The spectroscopic performance was assessed in photon fields and extracted from energy loss spectra measured at different angles in the pion beam. While at photon energies below 120 keV incomplete charge collection leads to an underestimation of the photon energy when irradiated from the front-side, at higher energies the relative energy resolution was found to be ∼4.5%, while a relative energy resolution of ∼7.5% was found for the particle energy loss spectra. It is shown that the drift time information can be used to reconstruct particle interactions in the sensor in 3D, providing a spatial resolution of σ xyz = 241 μm within the sensor volume and a particle trajectory measurement precision Δxyz = 100 μm, at a distance of 1 m from the sensor. We demonstrate by measurement with a 22Na source, that the energy resolution combined with the 3D reconstruction allows for detection of γ-ray source location and polarity using Compton scattering within the sensor (Compton camera and scatter polarimeter)

    Over-the-scope clip (OTSC (R)) closure of a recto-acetabular fistula

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    A 25-year-old male Syrian refugee presented in our hospital with recurrent hip infections after having undergone hip arthroplasty abroad following destruction of his right hip joint by shell splinters in the Syrian civil war. The patient underwent hip arthroplasty revision with implantation of a cement spacer. CT-scan with rectal contrast media filling revealed a rectoacetabular fistula. Consecutively, the patient underwent ileostomy formation. The fistula was then successfully closed by endoscopic over-the-scope clipping (OTSC (R)). Fistulas between intestines and joints rarely develop and in the few cases published mostly extensive abdominal rescue surgery has been performed. Here, we present a case of a traumatic rectoacetabular fistula that was successfully closed by OTSC. This innovative method could represent a safe and suitable option to effectively close fistulas between joints and intestines thereby avoiding extensive rescue surgery with bowel resection or permanent ostomy

    Genes in the postgenomic era

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    We outline three very different concepts of the gene - 'instrumental', 'nominal', and 'postgenomic'. The instrumental gene has a critical role in the construction and interpretation of experiments in which the relationship between genotype and phenotype is explored via hybridization between organisms or directly between nucleic acid molecules. It also plays an important theoretical role in the foundations of disciplines such as quantitative genetics and population genetics. The nominal gene is a critical practical tool, allowing stable communication between bioscientists in a wide range of fields grounded in well-defined sequences of nucleotides, but this concept does not embody major theoretical insights into genome structure or function. The post-genomic gene embodies the continuing project of understanding how genome structure supports genome function, but with a deflationary picture of the gene as a structural unit. This final concept of the gene poses a significant challenge to conventional assumptions about the relationship between genome structure and function, and between genotype and phenotype
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