212,494 research outputs found

    The culture of amber in Scotland

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    The last place most people will associate with amber is Scotland. Yet, it is the place where some of the oldest inclusions (from the Carboniferous) in tree resin have been found. Amber is defined differently by different cultures. Its precise origin is unknown, but is fossilised tree resin and not the sap. Some consider Baltic amber (or succinite) as the only true amber, but most would accept that other fossilised tree resins (such as the amber from the Eocene of the Dominican Republic, or the Cretaceous amber from the Isle of Wight) also exhibit similar properties. It may be surprising to some that the oldest ‘amber’ (also known as middletonite) to have been found with inclusions was found from the coalfields of Ayrshire in Scotland. John Smith published this discovery in 1894, describing the inclusions as parts of coniferous plants and fungi. Although the actual specimens John Smith studied are now lost to science, new research using some of the more modern techniques like 3D X-ray imaging, which looks at opaque amber, may eventually reveal evidence of such inclusions in this type of resin. There are also folklore and traditions associated with amber in Scotland, but, as yet, no sources for any amber (post-Carboniferous). So where has all this amber-lore come from? It was most likely brought by visitors and immigrants from Scandinavia and northern Europe over the millennia. Scotland has had strong historical and commercial links with these Baltic and other northern amber states that is reflected in the place names (such as John O’Groats or Valtos) and language (words like ‘Kirk’ or ‘Bairn’)

    New records of mosses from Dominican amber

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    Hypnum cupressiforme, Entodon macropus, Homalia glabella and Calyptothecium duplicatum are recorded as new from Dominican amber. Earlier records of Neckera spec. have to be transferred to Calyptothecium duplicatum. These records raise the total number of all mosses known from Dominican amber to 14. All mosses so far reported from Dominican amber are extant species which occur today in the Dominican Republic. This could indicate that the mossflora in the island of Hispaniola has not changed during the past 20-40 Mio years, but also falsifications of fossils in amber have to be taken into account, which can be suspected from the quality of some of the specimens

    The first fossil cyphophthalmid harvestman from Baltic amber

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    The first fossil cyphophthalmid harvestman (Opiliones: Cyphophthalmi) from Palaeogene (Eocene) Baltic amber is described. This is only the third fossil example of this basal harvestman lineage; the others being from the probably slightly younger Bitterfeld amber and the much older, early Cretaceous, Myanmar (Burmese) amber. Although incomplete and lacking most of the appendages, the new Baltic amber fossil can be identified as a female. The somatic characters preserved, especially spiracle morphology and the coxo-genital region, allow it to be assigned with some confidence to the extant genus Siro Latreille, 1796 (Sironidae). This fossil is formally described here as Siro balticus sp. nov. It resembles modern North American Siro species more than modern European ones, and can be distinguished principally on its relatively large size and the outline form of the body

    More records of mosses from Dominican amber

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    Hypnum spec., Orthostichella cf. pentasticha, Syrrhopodon flexifolius and Porotrichum aff. substriatum are recorded from Dominican amber (c. 25 mio yrs. b.p.). The first two species were known before from Dominican amber, the last two are newly reported

    "Advanced" data reduction for the AMBER instrument

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    The amdlib AMBER data reduction software is meant to produce AMBER data products from the raw data files that are sent to the PIs of different proposals or that can be found in the ESO data archive. The way defined by ESO to calibrate the data is to calibrate one science data file with a calibration one, observed as close in time as possible. Therefore, this scheme does not take into account instrumental drifts, atmospheric variations or visibility-loss corrections, in the current AMBER data processing software, amdlib. In this article, we present our approach to complement this default calibration scheme, to perform the final steps of data reduction, and to produce fully calibrated AMBER data products. These additional steps include: an overnight view of the data structure and data quality, the production of night transfer functions from the calibration stars observed during the night, the correction of additional effects not taken into account in the standard AMBER data reduction software such as the so-called "jitter" effect and the visibility spectral coherence loss, and finally, the production of fully calibrated data products. All these new features are beeing implemented in the modular pipeline script amdlibPipeline, written to complement the amdlib software.Comment: 10 pages, will be published in the proceeding of the SPIE conference "astronomical Telescopes and Instrumentation: Optical and Infrared Interferometry", held in Marseille from 23 to 27 june 200

    Fringe tracking performance monitoring: FINITO at VLTI

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    Since April 2011, realtime fringe tracking data are recorded simultaneously with data from the VLTI/AMBER interferometric beam combiner. Not only this offers possibilities to post-process AMBER reduced data to obtain more accurate interferometric quantities, it also allows to estimate the performance of the fringe tracking a function of the conditions of seeing, coherence time, flux, etc. First we propose to define fringe tracking performance metrics in the AMBER context, in particular as a function of AMBER's integration time. The main idea is to determine the optimal exposure time for AMBER: short exposures are dominated by readout noise and fringes in long exposures are completely smeared out. Then we present this performance metrics correlated with Paranal local ASM (Ambient Site Monitor) measurements, such as seeing, coherence time or wind speed for example. Finally, we also present some preliminary results of attempts to model and predict fringe tracking performances, using Artificial Neural Networks.Comment: SPIE conference, Optical and Infrared Interferometry II

    Regularities of hydromechanical amber extraction from sandy deposits

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    Purpose is to analyze the efficiency of hydromechanical amber extraction from sandy deposits relying upon the determined regularities concerning the effect of parameters while carrying out a series of laboratory tests and full-scale experiments. Methods. Laboratory tests and full-scale experiments (Volodymyrets amber-bearing deposit, village of Berezhnytsia) were carried out to analyze effect of the parameters of a hydromechanical technique on the velocity of amber extraction. The experiments also involved studies of occurrence medium; in this context, boiling process was modeled; and factors and parameters effecting suspense medium formation were researched. Methods of mathematical statistics were applied to obtain dependences describing mining parameters effect on amber extraction velocity. Findings. Basic parameters of hydromechanical technique, effecting amber extraction velocity, have been determined. Efficient values of air supply to provide maximum velocity of amber floating have been identified. Mathematical dependences, determining amber floating velocity depending upon air supply and mechanical effect frequency, have been obtained. In this context, amber production capacity is 90 to 95%. Basic parameters effecting amber mining (i.e. environmental density; amplitude of oscillations and their frequency; and water and air supply to sandy deposit of amber-bearing sand) have been defined. Originality. It has been first proved that amber floating velocity is of polynomial nature dependence upon environmental density where extremum is with 0.004 – 0.006 m3/h air supply value; amber extraction experiences 2 – 3 times intensification, if environmental density (ρc) is 1670 – 1750 kg/m3, oscillation frequency is 26 – 36 Hz, amplitude is A = 1.0 – 2.4 mm, and air supply is qa = 0.004 – 0.006 m3/h. In this context, amber floating (v) is 0.09 – 0.12 m/s. If air supply is more than qa = 0.020 m3/h, amber extraction process stops. It has been first obtained polynomial dependence of amber flotation on oscillation frequency of operating device as well as on air supply to rock mass. Practical implications. The determined regularities of hydromechanical amber extraction from amber-bearing sand help make calculations, and select facilities for hydromechanical amber mining.Мета. Дослідження ефективності процесу гідромеханічного вилучення бурштину з піщаних покладів на основі встановлених закономірностей впливу параметрів шляхом проведення серії лабораторних та натурних експериментів. Методика. Експериментальним шляхом в лабораторних та польових умовах (Володимирецьке бурштино-вмісне родовище, с. Бережниця) проведено дослідження впливу параметрів гідромеханічного способу вилучення на швидкість підняття бурштину. При проведенні експериментальних досліджень вивчалось середовище залягання, при цьому проводилось моделювання процесу кипіння й дослідження факторів і параметрів, що впливають на створення суспензного середовища. Із використанням методів математичної статистики отримано залежності, що описують вплив параметрів вилучення на швидкість підняття бурштину. Результати. Визначено основні параметри гідромеханічного методу, що впливають на швидкість вилучення бурштину. Встановлено раціональні значення величини подачі повітря для забезпечення максимальної швидкості спливання бурштину. Отримано математичні залежності, що визначають швидкість спливання залежно від по-дачі повітря та частоти механічного впливу, при цьому рівень видобутку бурштину сягає 90 – 95%. Визначені основні параметри, які впливають на інтенсивність підняття бурштину на денну поверхню, – густина середовища, амплітуда та частота коливань, подача води й повітря у піщане родовище бурштиновмісного піску. Наукова новизна. Вперше доведено, що швидкість спливання бурштину має поліноміальний характер залежності від густини середовища з екстремумом при величині подачі повітря 0.004 – 0.006 м3/год, а вилучення бурштину інтенсифікується у 2 – 3 рази при густині робочого середовища (ρc) 1670 – 1750 кг/м3, частоті коливання 26 – 36 Гц, амплітуді А = 1.0 – 2.4 мм, подачі повітря qa = 0.004 – 0.006 м3/год, при цьому швидкість спливання бурштину (v) рівна 0.09 – 0.12 м/с, а при збільшенні подачі повітря понад 0.020 м3/год процес вилучення бурштину припиняється. Вперше отримано поліноміальну залежність швидкості спливання бурштину від частоти коливань робочого органу та подачі повітря в масив. Практична значимість. Визначені закономірності гідромеханічного вилучення бурштину із бурштиновмісних пісків дозволяють проводити розрахунок та обирати обладнання для проведення гідромеханічного видобутку бурштину.Цель. Исследование эффективности процесса гидромеханического извлечения янтаря из песчаных залежей на основе установленных закономерностей влияния параметров путем проведения серии лабораторных и натурных экспериментов. Методика. Экспериментальным путем в лабораторных и полевых условиях (Владимирецкое янтарное месторождение, с. Бережница) проведено исследование влияния параметров гидромеханического способа извлечения на скорость всплытия янтаря. При проведении экспериментальных исследований изучалась среда залегания, при этом проводилось моделирование процесса кипения и исследование факторов и параметров, влияющих на создание суспензионной среды. С использованием методов математической статистики получены зависимости, описывающие влияние параметров извлечения на скорость всплытия янтаря. Результаты. Определены основные параметры гидромеханического способа, влияющие на скорость извлечения янтаря. Установлены рациональные значения величины подачи воздуха для обеспечения максимальной скорости всплытия янтаря. Получены математические зависимости, определяющие скорость всплытия в зависимости от подачи воздуха и частоты механического воздействия, при этом уровень добычи янтаря достигает 90 – 95%. Определены основные параметры, влияющие на интенсивность всплытия янтаря на дневную поверхность, – плотность среды, амплитуда и частота колебаний, подача воды и воздуха в песчаное месторождение янтарного песка. Научная новизна. Впервые доказано, что скорость всплытия янтаря имеет полиномиальный характер зависимости от плотности среды с экстремумом при величине подачи воздуха 0.004 – 0.006 м3/ч, а извлечение янтаря интенсифицируется в 2 – 3 раза при плотности рабочей среды (ρc) 1670 – 1750 кг/м3, частоте колебания 26 – 36 Гц, амплитуде А = 1.0 – 2.4 мм, подачи воздуха qa = 0.004 – 0.006 м3/ч, при этом скорость всплытия янтаря (v) равна 0.09 – 0.12 м/с, а при увеличении подачи воздуха более 0.020 м3/час процесс извлечения янтаря завершается. Впервые получена полиномиальная зависимость скорости всплытия янтаря от частоты колебаний рабочего органа и от подачи воздуха в массив. Практическая значимость. Установленные закономерности гидромеханического извлечения янтаря с янтарных песков позволяют производить расчет и выбирать оборудование для проведения гидромеханической добычи янтаря.The studies have been carried out on the basis of the National University of Water and Environmental Engineering (town of Rivne), and with the participation of the experts from “Ukrainska Heolohichna Kompania” SE (Volyn Surveying Company, town of Kovel). The authors express thanks to a Vice-Rector for Research of the National University of Water and Environmental Engineering, Doctor of Ecological Sciences N.B. Savina for the opportunity to perform the research using laboratory equipment of the University, and to the authorities of “Ukrainska Heolohichna Kompania” SE for joint research within Volodymyrets amber-bearing deposit (a village of Bereznytsia)

    Testing evolutionary tracks of Pre-Main Sequence stars: the case of HD113449

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    Evolutionary tracks are of key importance for the understanding of star formation. Unfortunately, tracks published by various groups differ so that it is fundamental to have observational tests. In order to do this, we intend to measure the masses of the two components of the Pre-Main Sequence binary HD113449 by combining radial velocity measurements taken with HARPS, with infrared interferometric data using AMBER on the VLTI. The spectroscopic orbit that has already been determined, combined with the first AMBER measurement, allows us to obtain a very first estimation of the inclination of the binary system and from this the masses of the two stars. More AMBER measurements of HD 113449 are needed to improve the precision on the masses: in the ESO period P82 two new measurements are scheduled.Comment: 4 pages, 3 figures; to appear in proceedings of Cool Star 15 conference, St.Andrews 200

    First astrophysical results from AMBER/VLTI

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    The AMBER instrument installed at the Very Large Telescope (VLT) combines three beams from as many telescopes to produce spectrally dispersed fringes from milli-arcsecond angular scale in the near infrared. Two years after installation, first scientific observations have been carried out during the Science Demonstration Time and the Guaranteed Time mostly on bright sources due to some VLTI limitations. In this paper, we review these first astrophysical results and we show which types of completely new information is brought by AMBER. The first astrophysical results have been mainly focusing on stellar wind structure, kinematics, and its interaction with dust usually concentrated in a disk. Because AMBER has dramatically increased the number of measures per baseline, this instrument brings strong constraints on morphology and models despite a relatively poor (u, v) coverage for each object.Comment: SPIE 6268 proceeding
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