67 research outputs found

    Аналіз фінансово-економічних передумов створення фінансового кластеру в західному регіоні України

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    У статті проведено аналіз фінансового забезпечення суб’єктів підприємницької діяльності Західного регіону України, визначено основні проблеми цього регіону і можливості їх вирішення шляхом створення фінансового кластеру. Запропоновано модель фінансового кластеру регіону та виділено основних потенційних учасників об’єднання.В статье проведен анализ финансового обеспечения субъектов предпринимательской деятельности Западного региона Украины, определены основные проблемы региона и возможности их решения путем создания финансового кластера. Предложена модель финансового кластера региона и выделены основные потенциальные участники объединения.The financial support of entrepreneurs in the Western region of Ukraine is analyzed in the article. The main problems of the region are identified and are proposed the methods to solve them developing a financial cluster. The model of financial cluster is proposed and the basic participants of association are selected

    A low attenuation layer in the Earth's uppermost inner core

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    The attenuation structure of the Earth's inner core, in combination with the velocity structure, provides much insight into its rheological and mineralogical properties. Here, we use a large data set of PKIKP/PKiKP amplitude ratios to derive attenuation models for the upper 100 km of the inner core, incorporating the effects of velocity models calculated using the same data set. We confirm that the upper inner core is hemispherical in attenuation, with stronger attenuation in the east hemisphere. We also observe, for the first time, a low attenuation upper layer of approximately 30 km thickness throughout the top of the inner core. Attenuation increases beneath this layer, and then gradually decreases going deeper into the inner core. Although the data appear to show attenuation anisotropy below 57.5 km depth in the west, we find that this can be explained by the velocity models alone, with no requirement for attenuation anisotropy in the upper inner core

    Large-scale mantle discontinuity topography beneath Europe: Signature of akimotoite in subducting slabs

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    The mantle transition zone is delineated by seismic discontinuities around 410 and 660 km, which are generally related to mineral phase transitions. Study of the topography of the discontinuities further constrains which phase transitions play a role and, combined with their Clapeyron slopes, what temperature variations occur. Here we use P to S converted seismic waves or receiver functions to study the topography of the mantle seismic discontinuities beneath Europe and the effect of subducting and ponding slabs beneath southern Europe on these features. We combine roughly 28,000 of the highest quality receiver functions into a common conversion point stack. In the topography of the discontinuity around 660 km, we find broadscale depressions of 30 km beneath central Europe and around the Mediterranean. These depressions do not correlate with any topography on the discontinuity around 410 km. Explaining these strong depressions by purely thermal effects on the dissociation of ringwoodite to bridgmanite and periclase requires unrealistically large temperature reductions. Presence of several wt % water in ringwoodite leads to a deeper phase transition, but complementary observations, such as elevated Vp/Vs ratio, attenuation, and electrical conductivity, are not observed beneath central Europe. Our preferred hypothesis is the dissociation of ringwoodite into akimotoite and periclase in cold downwelling slabs at the bottom of the transition zone. The strongly negative Clapeyron slope predicted for the subsequent transition of akimotoite to bridgmanite explains the depression with a temperature reduction of 200–300 K and provides a mechanism to pond slabs in the first place

    Observations of core‐mantle boundary Stoneley modes

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    Core‐mantle boundary (CMB) Stoneley modes represent a unique class of normal modes with extremely strong sensitivity to wave speed and density variations in the D” region. We measure splitting functions of eight CMB Stoneley modes using modal spectra from 93 events with M w > 7.4 between 1976 and 2011. The obtained splitting function maps correlate well with the predicted splitting calculated for S20RTS+Crust5.1 structure and the distribution of S diff and P diff travel time anomalies, suggesting that they are robust. We illustrate how our new CMB Stoneley mode splitting functions can be used to estimate density variations in the Earth's lowermost mantle. Key Points We present CMB Stoneley mode splitting function measurements The CMB Stoneley mode splitting correlates well with diffracted body wave data Our measurements allow to constrain density variations in the lowermost mantlePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/1/figS2_plot_prem_freq_Q_stoneley_paperrotated.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/2/grl50514.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/3/figS1_plot_coef_stoneley_paper_deg2_newrotated.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99080/4/README_suppl_mat_GRL.pd

    A new catalogue of normal-mode splitting function measurements up to 10 mHz

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    The splitting of the Earth's free-oscillation spectra places important constraints on the wave speed and density structure of the Earth's mantle and core. We present a new set of 164 self-coupled and 32 cross-coupled splitting functions. They are derived from modal spectra up to 10 mHz for 91 events with Mw ≥ 7.4 from the last 34 yr (1976–2010). Our data include the 2001 June 23 Peru event (Mw = 8.4), the Sumatra events of 2004 (Mw = 9.0) and 2005 (Mw = 8.6), the 2008 Wenchuan, China event (Mw = 7.9) and the 2010 Chile event (Mw = 8.8). The new events provide significant improvement of data coverage particularly in continental areas. Almost half of the splitting functions have never been measured before. In particular, we measured 33 new modes sensitive to mantle compressional wave velocity, 10 new inner-core sensitive modes and 22 new cross-coupled splitting functions. These provide new constraints on the large-scale compressional structure of the mantle and the odd-degree structure of the mantle and inner core and can be used in future inversions of heterogeneous Earth structure. Our new splitting function coefficient data set will be available online

    Inner core structure behind the PKP core phase triplication

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    The structure of the Earth's inner core is not well known between depths of ∼100–200 km beneath the inner core boundary. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, which hinder the measurement of inner core compressional PKIKP waves at epicentral distances between roughly 143 and 148°. Consequently, interpretation of the detailed structure of deeper regions also remains difficult. To overcome these issues we stack seismograms in slowness and time, separating the PKP and PKIKP phases which arrive simultaneously but with different slowness. We apply this method to study the inner core's Western hemisphere beneath South and Central America using paths travelling in the quasi-polar direction between 140 and 150° epicentral distance, which enables us to measure PKiKP–PKIKP differential traveltimes up to greater epicentral distance than has previously been done. The resulting PKiKP–PKIKP differential traveltime residuals increase with epicentral distance, which indicates a marked increase in seismic velocity for polar paths at depths greater than 100 km compared to reference model AK135. Assuming a homogeneous outer core, these findings can be explained by either (i) inner core heterogeneity due to an increase in isotropic velocity or (ii) increase in anisotropy over the studied depth range. Although this study only samples a small region of the inner core and the current data cannot distinguish between the two alternatives, we prefer the latter interpretation in the light of previous work

    3D transdimensional seismic tomography of the inner core

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    Body wave observations of the Earth's inner core show that it contains strong seismic heterogeneity, both laterally and radially. Models of inner core structure generated using body wave data are often limited by their parameterisation. Thus, it is difficult to determine whether features such as anisotropic hemispheres or an innermost inner core truly exist with their simple shapes, or result only from the chosen parameterisation and are in fact more complex features. To overcome this limitation, we conduct seismic tomography using transdimensional Markov Chain Monte Carlo on a high quality dataset of 5296 differential and 2344 absolute P-wave travel times. In a transdimensional approach, the data defines the model space parameterisation, providing us with both the mean value of each model parameter and its probability distribution, allowing us to identify well versus poorly constrained regions. We robustly recover many first order observations found in previous studies without the imposition of a priori fixed geometry including an isotropic top layer (with anisotropy less than 1%) which is between 60 and 170 km thick, and separated into hemispheres with a slow west and a faster east. Strong anisotropy (with a maximum of 7.2%) is found mainly in the west, with much weaker anisotropy in the east. We observe for the first time that the western anisotropic zone is largely confined to the northern hemisphere, a property which would not be recognised in models assuming a simple hemispherical parameterisation. We further find that the inner most inner core, in which the slowest anisotropic velocity direction is tilted relative to Earth's axis of rotation (zeta = 55 & PLUSMN; 16), is offset by 400 km from the centre of the inner core and is restricted to the eastern hemisphere. We propose that this anomalous anisotropy might indicate the presence of a different phase of iron (either bcc or fcc) compared to the rest of the inner core (hcp)

    Роль маркетинга в сфере культуры

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    Сегодня все мы ощущаем завершение очередного этапа развития нашего общества, который выражается в многочисленных кризисах (политическом, экономическом, экологическом и т.д.), что в полной мере отражает художественная культура

    № 138. Протокол допиту Володимира Чехівського від 1 жовтня 1929 р.

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    The structure of the Earth's inner core is not well known between depths of ∼100–200 km beneath the inner core boundary. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, which hinder the measurement of inner core compressional PKIKP waves at epicentral distances between roughly 143 and 148°. Consequently, interpretation of the detailed structure of deeper regions also remains difficult. To overcome these issues we stack seismograms in slowness and time, separating the PKP and PKIKP phases which arrive simultaneously but with different slowness. We apply this method to study the inner core's Western hemisphere beneath South and Central America using paths travelling in the quasi-polar direction between 140 and 150° epicentral distance, which enables us to measure PKiKP–PKIKP differential traveltimes up to greater epicentral distance than has previously been done. The resulting PKiKP–PKIKP differential traveltime residuals increase with epicentral distance, which indicates a marked increase in seismic velocity for polar paths at depths greater than 100 km compared to reference model AK135. Assuming a homogeneous outer core, these findings can be explained by either (i) inner core heterogeneity due to an increase in isotropic velocity or (ii) increase in anisotropy over the studied depth range. Although this study only samples a small region of the inner core and the current data cannot distinguish between the two alternatives, we prefer the latter interpretation in the light of previous work

    Exact free oscillation spectra, splitting functions and the resolvability of earth's density structure

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    Seismic free oscillations, or normal modes, provide a convenient tool to calculate low-frequency seismograms in heterogeneous Earth models. A procedure called ‘full mode coupling’ allows the seismic response of the Earth to be computed. However, in order to be theoretically exact, such calculations must involve an infinite set of modes. In practice, only a finite subset of modes can be used, introducing an error into the seismograms. By systematically increasing the number of modes beyond the highest frequency of interest in the seismograms, we investigate the convergence of full-coupling calculations. As a rule-of-thumb, it is necessary to couple modes 1–2 mHz above the highest frequency of interest, although results depend upon the details of the Earth model. This is significantly higher than has previously been assumed. Observations of free oscillations also provide important constraints on the heterogeneous structure of the Earth. Historically, this inference problem has been addressed by the measurement and interpretation of splitting functions. These can be seen as secondary data extracted from low frequency seismograms. The measurement step necessitates the calculation of synthetic seismograms, but current implementations rely on approximations referred to as self- or group-coupling and do not use fully accurate seismograms. We therefore also investigate whether a systematic error might be present in currently published splitting functions. We find no evidence for any systematic bias, but published uncertainties must be doubled to properly account for the errors due to theoretical omissions and regularization in the measurement process. Correspondingly, uncertainties in results derived from splitting functions must also be increased. As is well known, density has only a weak signal in low-frequency seismograms. Our results suggest this signal is of similar scale to the true uncertainties associated with currently published splitting functions. Thus, it seems that great care must be taken in any attempt to robustly infer details of Earth's density structure using current splitting functions.The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Seventh Framework Programme (FP/2007-2013) grant agreement number 320639 (iGEO) and under the European Union’s Horizon 2020 research and innovation programme grant agreement number 681535 (ATUNE)
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