1,656 research outputs found

    Description of a new species of Afroedura (Loveridge) (Reptilia: Gekkonidae) from the south-western Cape

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    A new gekkonid species, Afroedura hawequensis, is described from the south-western Cape (South Africa). The three species groups recognized in the genus are discussed

    Dynamic critical behavior of the classical anisotropic BCC Heisenberg antiferromagnet

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    Using a recently implemented integration method [Krech et. al.] based on an iterative second-order Suzuki-Trotter decomposition scheme, we have performed spin dynamics simulations to study the critical dynamics of the BCC Heisenberg antiferromagnet with uniaxial anisotropy. This technique allowed us to probe the narrow asymptotic critical region of the model and estimate the dynamic critical exponent z=2.25±0.08z=2.25 \pm 0.08. Comparisons with competing theories and experimental results are presented.Comment: Latex, 3 pages, 5 figure

    Dissipation of vibration in rough contact

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    The relationship which links the normal vibration occurring during the sliding of rough surfaces and the nominal contact area is investigated. Two regimes are found. In the first one, the vibrational level does not depend on the contact area, while in the second one, it is propor- tional to the contact area. A theoretical model is proposed. It is based on the assumption that the vibrational level results from a competition between two processes of vibration damping, the internal damping of the material and the contact damping occurring at the interface

    Surface critical behavior in fixed dimensions d<4d<4: Nonanalyticity of critical surface enhancement and massive field theory approach

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    The critical behavior of semi-infinite systems in fixed dimensions d<4d<4 is investigated theoretically. The appropriate extension of Parisi's massive field theory approach is presented.Two-loop calculations and subsequent Pad\'e-Borel analyses of surface critical exponents of the special and ordinary phase transitions yield estimates in reasonable agreement with recent Monte Carlo results. This includes the crossover exponent Φ(d=3)\Phi (d=3), for which we obtain the values Φ(n=1)0.54\Phi (n=1)\simeq 0.54 and Φ(n=0)0.52\Phi (n=0)\simeq 0.52, considerably lower than the previous ϵ\epsilon-expansion estimates.Comment: Latex with Revtex-Stylefiles, 4 page

    Скрининг экстрактов лекарственных растений на ингибирующую активность ксантиноксидазы

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    Objectives. The study aimed to test the ethanol extracts of ten medicinal plants for xanthine oxidase inhibitory activity.Methods. The degree of xanthine oxidase inhibitory activity was determined by measuring the absorbance spectrophotometrically at 290 nm, which is associated with uric acid formation. The selected medicinal plants included Piper lolot C.DC. (Piperaceae), Pandanus amaryllifolius R.(Pandanaceae), Brassica juncea L. (Brassicaceae), Piper betle L. (Piperaceae), Perilla frutescens L. (Lamiaceae), Anacardium occidentale L. (Anacardiaceae), Polygonum barbatum L. (Polygonaceae), Artocarpus Altilis P. (Moraceae), Vitex negundo L. (Verbenaceae), Annona squamosal L. (Annonaceae), which were selected based on folk medicine.Results. The results showed that the Piper betle L. has a strong ability to inhibit xanthine oxidase with an IC50 value of up to 1.18 μg/mL, compared to allopurinol 1.57 μg/mL. Different parts of Piper betle L. were compared and the leaves of Piper betle L. showed the best value for xanthine oxidase inhibitory and antioxidant activity.Conclusions. Piper betle L. showed the best potential for inhibition of xanthine oxidase among ten medicinal plants. Piper betle L. leaf extract showed strong xanthine oxidase inhibitory and antioxidant activity, compared to the whole plant, and the stem extract, which promises to be applied in the treatment of gout.Цели. Исследование было направлено на проверку этанольных экстрактов десяти лекарственных растений на ингибиторную активность ксантиноксид азы.Методы. Степень ингибирующей активности ксантиноксидазы определяли путем спектрофотометрического измерения поглощения при 290 нм, вызываемого образованием мочевой кислоты. В состав отобранных лекарственных растений вошли перец-лолот (Piperaceae), пандан (Pandanaceae), горчица сарептская (Brassicaceae), бетель (Piperaceae), перилла обыкновенная (Lamiaceae), кешью (Anacardiaceae), конопля (Polygonaceae), хлебное дерево (Moraceae), прутняк китайский (Verbenaceae), сахарное яблоко (Annonaceae), отобранные на основе их применения в народ ной медицине.Результаты. Результаты показали, что бетель обладает сильной способностью ингибировать ксантиноксидазу со значением IC50 до 1.18 мкг/мл по сравнению с аллопуринолом 1.57 мкг/мл. Были проведены сравнения различных частей бетеля, и листья бетеля показали наилучшие показатели ингибирования ксантиноксидазы и антиоксидантной активности.Выводы. Бетель показал лучший потенциал ингибирования ксантиноксидазы среди десяти лекарственных растений. Экстракт листьев бетеля показал сильное подавление ксантиноксидазы и антиоксидантную активность по сравнению с целым растением и экстрактом стебля, которые применяются при лечении подагры

    La pobreza en Cartagena: un análisis por barrios

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    En el presente documento se hace un análisis descriptivo de la pobreza urbana enCartagena. El tema se aborda desde dos perspectivas. En la primera, se analiza lapobreza desagregada por los barrios que conforman la cabecera municipal deCartagena. En la segunda, se realiza una comparación de la situaciónsocioeconómica de los habitantes de Cartagena con la de las principales ciudades deColombia. Vale la pena mencionar que este trabajo es pionero no sólo en Cartagenasino en Colombia, en cuanto al nivel de división por barrios al que se analizanindicadores socioeconómicos, tales como la pobreza, el ingreso, los logroseducativos, la migración y el autorreconocimiento racial. Dentro de los principalesresultados se comprobó una focalización espacial de la pobreza en sectoresespecíficos de la ciudad, tales como las laderas del Cerro de la Popa y los barriosaledaños a la Ciénaga de la Virgen. En estas zonas de la ciudad se concentra no sólola población más pobre sino la de menores logros educativos. Otro resultadointeresante, y que está acorde con la literatura internacional, es que en los barrioscartageneros de mayor pobreza existe también una alta proporción de habitantes quese autorreconocen de raza negra.Pobreza urbana, Cartagena, economía regional y urbana

    Young people, crime and school exclusion: a case of some surprises

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    During the 1990s the number of young people being permanently excluded from schools in England and Wales increased dramatically from 2,910 (1990/91) to a peak of 12,700 (1996/97). Coinciding with this rise was a resurgence of the debate centring on lawless and delinquent youth. With the publication of Young People and Crime (Graham and Bowling 1995) and Misspent Youth (Audit Commission 1996) the 'common sense assumption' that exclusion from school inexorably promoted crime received wide support, with the school excludee portrayed as another latter day 'folk devil'. This article explores the link between school exclusion and juvenile crime, and offers some key findings from a research study undertaken with 56 young people who had experience of being excluded from school. Self-report interview questions reveal that whilst 40 of the young people had offended, 90% (36) reported that the onset of their offending commenced prior to their first exclusion. Moreover, 50 (89.2% of the total number of young people in the sample), stated that they were no more likely to offend subsequent to being excluded and 31 (55.4%) stated that they were less likely to offend during their exclusion period. Often, this was because on being excluded, they were 'grounded' by their parents

    Оптимизация общего содержания флавоноидов в спиртовом экстракте Persicaria pulchra (Bl.) Soják для ингибирования фермента α-глюкозидазы

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    Objectives. There has been a rapid increase in the number of diabetic patients since the past few decades in developed and developing countries. This rapid increase is accompanied by alarming costs of treatment. α-Glucosidase inhibitors are one of the most effective drugs employed for the reduction of postprandial hyperglycemia to manage Type 2 diabetes mellitus. Additionally, flavonoids, a group of natural substances, which are widely distributed in plants and possess variable phenolic structures, exhibit outstanding hypoglycemic activity and are considered as potential α-glucosidase inhibitors. In Vietnam, Persicaria pulchra (Bl.) Soják (P. pulchra) is employed in traditional medications. It possesses high flavonoid contents and its anti-diabetes ability has been hypothesized, although it has attracted less attention for investigation. Hence, the aim of this study is to optimize the condition of the P. pulchra extract to obtain the highest total flavonoid content and measure the bioactivities of P. pulchra, such as the anti-α-glucosidase and antioxidant activities.Methods. The effects of the extracting conditions, including the temperature, extraction time, liquid-to-solid ratio (LSR), and ethanol (C2H5OH) concentration, on the total flavonoid content are investigated via experiments and analyzed by the response surface methodology (RSM). Concurrently, the optimal extraction also determines the anti-α-glucosidase and antioxidant activities.Results. The optimal extraction condition for the highest flavonoid content (530 mg quercetin/g) is determined in 60 min, at 53°C, with LSR of 9.46 g/g and C2H5OH concentration of 62%. Moreover, the optimal plant extract exhibits good α-glucosidase inhibition with a half-maximal inhibitory concentration (IC50) of 22.67 mg/mL, compared to the positive control (acarbose −7.77 g/mL). Additionally, P. pulchra is proposed to be a potential antioxidant with an IC50 of ~12.68 µg/mL.Conclusions. The study confirmed the optimal extraction condition of P. pulchra that will obtain the highest total flavonoid content and revealed the potentials of P. pulchra in α-glucosidase inhibition and antioxidation.Цели. В последние десятилетия в развитых и развивающихся странах наблюдается быстрый рост числа больных диабетом, который сопровождается ростом стоимости лечения. Ингибиторы α-глюкозидазы являются одним из наиболее эффективных препаратов, применяемых для снижения постпрандиальной гипергликемии при лечении сахарного диабета 2 типа. Кроме того, флавоноиды, группа природных веществ, широко распространенных в растениях и содержащих различные производные фенола, проявляют значительную гипогликемическую активность и могут служить потенциальными ингибиторами α-глюкозидазы. Во Вьетнаме Persicaria pulchra (Bl.) Soják (P. pulchra) используется в народной медицине. Он обладает высоким содержанием флавоноидов и, предположительно, противодиабетическими свойствами, хотя исследован мало. Таким образом, целью настоящего исследования является оптимизация экстрагирования P. pulchra для получения наиболее высокого общего содержания флавоноидов, а также определение его биологической активности – анти-α-глюкозидазной и антиоксидантной. Методы. Экспериментально исследовано влияние условий экстрагирования, а именно температуры, времени экстракции, соотношения жидкость : твердое вещество и концентрации этанола, на общее содержание флавоноидов с помощью методологии анализа поверхности отклика. Показано, что оптимальные условия экстракции определяют анти-α-глюкозидазную и антиоксидантную активность.Результаты. Найдены оптимальные условия экстракции для получения максимального содержания флавоноидов (530 мг кверцетина/г): время экстракции 60 мин, температура 53 °С, отношение жидкость : твердое вещество 9.46 г/г и концентрация этанола 62%. Растительный экстракт, полученный в оптимальных условиях, проявляет хорошее ингибирование α-глюкозидазы с концентрацией полумаксимального ингибирования (IC50) 22.67 мг/мл по сравнению с положительным контролем (акарбоза – 7.77 г/мл). Выводы. Исследование выявило оптимальные условия экстракции P. pulchra, позволяющие получить наиболее высокое общее содержание флавоноидов, и подтвердило перспективы применения P. pulchra для ингибировании α-глюкозидазы и антиоксидантного окисления

    A possible resolution of the CDF psi^prime anomaly

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    We consider the contribution of radially excited 2^3P_{1,2} states to psi^prime production at the Tevatron energy. Production of these states via the conventional gluon fusion mechanism and via gluon and charm quark fragmentation processes is considered. We find that it is possible to account for the data on psi^prime production from the CDF experiment, by taking into account the decays of these 2^3P_{1,2} states into psi^prime.Comment: 8 pages + 1 figure (available upon request), CERN-TH.7434/9

    3D macro- and microfabric analyses of Neoproterozoic diamictites from the Valjean Hills, California (United States)

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    The Cryogenian interval (720–635 Ma) is famous for a rich archive of diamictites, many of which were deposited during glaciations. Classic examples are exposed in the Kingston Peak Formation of the Valjean Hills, near Death Valley (United States), with previous work pointing to multiple glacial cycles in other outcrop belts. Within any glacial period, diamictites are widespread, and in addition, their mechanics of deposition are highly variable. Some are massive in appearance at outcrop or in hand specimens and apparently lack any information that allows their mode of emplacement to be elucidated. Yet, the correct interpretation for deep-time successions in this area is especially important, since it is debated whether the diamictites are either associated with a tectonically driven origin, associated with rifting at the south-western Laurentian margin alongside slope-controlled gravitational mass movement, or predominantly deposited as (sub)glacial diamictites. In this paper, we demonstrate how diamictite texture can be objectively quantified based on clast orientations, at both macroscale and microscale (micromorphology), guiding interpretations. Our method is based on a technique used for Quaternary sediments, by mapping the apparent longest axes of skeleton grains (ranging from fine-grained sand to fine-grained pebbles) in oriented thin sections and reconstructing their microfabric in a 3D space coupled with macrofabric data for each diamictite. In this way, we could identify a bimodal signal in the orientation of the longest axes for each sample. Evidence for shearing and soft sediment deformation supports either subaqueous or subglacial deposition with deformation induced by basal sliding with a paleoflow directed toward the southeast. Our combined approach of micro- and macrofabric analyses can also encourage acquiring accurate fabric data for seemingly structureless diamictites from other deep-time rock archives in an objective manner
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