257 research outputs found
The institutional factors of strategic development and the tactical regulation of nanotechnology
The analysis of influence of institutional factors on development of technologies is carried out. The generating role of institutions in technological progress is proved. The general logic of an institutionalization of new technological way is presented on an example of nanotechnologies.
Institutes are the “weak link” of the concepts and theories of the evolution of technology and technological structures. Most modern theorists of evolutionary economics are focused mainly on the study of the dynamics and forms of scientific and technological progress, especially the mechanisms of nucleation and diffusion of large “clusters” of innovation.
In their turn, the institutional economists have concentrated on the analysis of factors and ways to minimize the transaction costs sustained interaction of agents and their organizations “in the high-tech world with a huge degree of specialization and division of labor other than impersonal exchange” (North 1997).
In their works only relate to the institutional structure and infrastructure of innovative development, although, as noted by Nelson (2002), the concept of national and regional innovation systems is institutional in nature just on this fact is rarely emphasizes the attention of scientists. As a result, institutional forms and mechanisms of technological evolution is very poorly understood, and their analysis is based on very general ideas about the institutes and institutions.peer-reviewe
Broadband dielectric spectroscopy on benzophenone: alpha relaxation, beta relaxation, and mode coupling theory
We have performed a detailed dielectric investigation of the relaxational
dynamics of glass-forming benzophenone. Our measurements cover a broad
frequency range of 0.1 Hz to 120 GHz and temperatures from far below the glass
temperature well up into the region of the small-viscosity liquid. With respect
to the alpha relaxation this material can be characterized as a typical
molecular glass former with rather high fragility. A good agreement of the
alpha relaxation behavior with the predictions of the mode coupling theory of
the glass transition is stated. In addition, at temperatures below and in the
vicinity of Tg we detect a well-pronounced beta relaxation of Johari-Goldstein
type, which with increasing temperature develops into an excess wing. We
compare our results to literature data from optical Kerr effect and depolarized
light scattering experiments, where an excess-wing like feature was observed in
the 1 - 100 GHz region. We address the question if the Cole-Cole peak, which
was invoked to describe the optical Kerr effect data within the framework of
the mode coupling theory, has any relation to the canonical beta relaxation
detected by dielectric spectroscopy.Comment: 11 pages, 7 figures; revised version with new Fig. 5 and some smaller
changes according to referees' demand
Dielectric spectroscopy in benzophenone: The beta relaxation and its relation to the mode-coupling Cole-Cole peak
We report a thorough characterization of the glassy dynamics of benzophenone
by broadband dielectric spectroscopy. We detect a well pronounced beta
relaxation peak developing into an excess wing with increasing temperature. A
previous analysis of results from Optical-Kerr-effect measurements on this
material within the mode coupling theory revealed a high-frequency Cole-Cole
peak. We address the question if this phenomenon also may explain the
Johari-Goldstein beta relaxation, a so far unexplained spectral feature
inherent to glass-forming matter, mainly observed in dielectric spectra. Our
results demonstrate that according to the present status of theory, both
spectral features seem not to be directly related.Comment: 4 pages, 3 figures; second version as published; small changes of
text according to referee suggestions; title changed according to editor's
demand
Genetic and morphologic determination of diatom community composition in surface sediments from glacial and thermokarst lakes in the Siberian Arctic
Lakes cover large parts of the climatically sensitive Arctic landscape and respond rapidly to environmental change. Arctic lakes have different origins and include the predominant thermokarst lakes, which are small, young and highly dynamic, as well as large, old and stable glacial lakes. Freshwater diatoms dominate the primary producer community in these lakes and can be used to detect biotic responses to climate and environmental change. We used specific diatom metabarcoding on sedimentary DNA, combined with next-generation sequencing and diatom morphology, to assess diatom diversity in five glacial and 15 thermokarst lakes within the easternmost expanse of the Siberian treeline ecotone in Chukotka, Russia. We obtained 163 verified diatom sequence types and identified 176 diatom species morphologically. Although there were large differences in taxonomic assignment using the two approaches, they showed similar high abundances and diversity of Fragilariceae and Aulacoseiraceae. In particular, the genetic approach detected hidden within-lake variations of fragilarioids in glacial lakes and dominance of centric Aulacoseira species, whereas Lindavia ocellata was predominant using morphology. In thermokarst lakes, sequence types and valve counts also detected high diversity of Fragilariaceae, which followed the vegetation gradient along the treeline. Ordination analyses of the genetic data from glacial and thermokarst lakes suggest that concentrations of sulfate, an indicator of the activity of sulfate-reducing microbes under anoxic conditions, and bicarbonate, which relates to surrounding vegetation, have a significant influence on diatom community composition. For thermokarst lakes, we also identified lake depth as an important variable, but sulfate best explains diatom diversity derived from genetic data, whereas bicarbonate best explains the data from valve counts. Higher diatom diversity was detected in glacial lakes, most likely related to greater lake age and different edaphic settings, which gave rise to diversification and endemism. In contrast, small, dynamic thermokarst lakes are inhabited by stress-tolerant fragilarioids and are related to different vegetation types along the treeline ecotone. Our study demonstrated that genetic investigations of lake sediments can be used to interpret climate and environmental responses of diatoms. It also showed how lake type affects diatom diversity, and that such genetic analyses can be used to track diatom community changes under ongoing warming in the Arctic
Josephson diode effect from Cooper pair momentum in a topological semimetal
Cooper pairs in non-centrosymmetric superconductors can acquire finite centre-of-mass momentum in the presence of an external magnetic field. Recent theory predicts that such finite-momentum pairing can lead to an asymmetric critical current, where a dissipationless supercurrent can flow along one direction but not in the opposite one. Here we report the discovery of a giant Josephson diode effect in Josephson junctions formed from a type-II Dirac semimetal, NiTe2. A distinguishing feature is that the asymmetry in the critical current depends sensitively on the magnitude and direction of an applied magnetic field and achieves its maximum value when the magnetic field is perpendicular to the current and is of the order of just 10 mT. Moreover, the asymmetry changes sign several times with an increasing field. These characteristic features are accounted for by a model based on finite-momentum Cooper pairing that largely originates from the Zeeman shift of spin-helical topological surface states. The finite pairing momentum is further established, and its value determined, from the evolution of the interference pattern under an in-plane magnetic field. The observed giant magnitude of the asymmetry in critical current and the clear exposition of its underlying mechanism paves the way to build novel superconducting computing devices using the Josephson diode effect
Collapse arrest and soliton stabilization in nonlocal nonlinear media
We investigate the properties of localized waves in systems governed by
nonlocal nonlinear Schrodinger type equations. We prove rigorously by bounding
the Hamiltonian that nonlocality of the nonlinearity prevents collapse in,
e.g., Bose-Einstein condensates and optical Kerr media in all physical
dimensions. The nonlocal nonlinear response must be symmetric, but can be of
completely arbitrary shape. We use variational techniques to find the soliton
solutions and illustrate the stabilizing effect of nonlocality.Comment: 4 pages with 3 figure
Modulational instability, solitons and beam propagation in spatially nonlocal nonlinear media
We present an overview of recent advances in the understanding of optical
beams in nonlinear media with a spatially nonlocal nonlinear response. We
discuss the impact of nonlocality on the modulational instability of plane
waves, the collapse of finite-size beams, and the formation and interaction of
spatial solitons.Comment: Review article, will be published in Journal of Optics B, special
issue on Optical Solitons, 6 figure
Palladium-Ceria Catalysts with Enhanced Alkaline Hydrogen Oxidation Activity for Anion Exchange Membrane Fuel Cells
International audienc
Contrasts in dissolved, particulate, and sedimentary organic carbon from the Kolyma River to the East Siberian Shelf
Arctic rivers will be increasingly affected by the
hydrological and biogeochemical consequences of thawing permafrost. During
transport, permafrost-derived organic carbon (OC) can either accumulate in
floodplain and shelf sediments or be degraded into greenhouse gases prior to
final burial. Thus, the net impact of permafrost OC on climate will
ultimately depend on the interplay of complex processes that occur along the
source-to-sink system. Here, we focus on the Kolyma River, the largest
watershed completely underlain by continuous permafrost, and marine
sediments of the East Siberian Sea, as a transect to investigate the fate of
permafrost OC along the land–ocean continuum. Three pools of riverine OC
were investigated for the Kolyma main stem and five of its tributaries:
dissolved OC (DOC), suspended particulate OC (POC), and riverbed sediment OC
(SOC). They were compared with earlier findings in marine sediments. Carbon isotopes
(δ13C, Δ14C), lignin phenol, and lipid biomarker
proxies show a contrasting composition and degradation state of these
different carbon pools. Dual C isotope source apportionment calculations
imply that old permafrost-OC is mostly associated with sediments (SOC;
contribution of 68±10 %), and less dominant in POC (38±8 %), whereas autochthonous primary production contributes around 44±10 % to POC in the main stem and up to 79±11 % in tributaries.
Biomarker degradation indices suggest that Kolyma DOC might be relatively
degraded, regardless of its generally young age shown by previous studies.
In contrast, SOC shows the lowest Δ14C value (oldest OC), yet
relatively fresh compositional signatures. Furthermore, decreasing mineral
surface area-normalised OC- and biomarker loadings suggest that SOC might be
reactive along the land–ocean continuum and almost all parameters were
subjected to rapid change when moving from freshwater to the marine
environment. This suggests that sedimentary dynamics play a crucial role
when targeting permafrost-derived OC in aquatic systems and support earlier
studies highlighting the fact that the land–ocean transition zone is an efficient
reactor and a dynamic environment. The prevailing inconsistencies between
freshwater and marine research (i.e. targeting predominantly DOC and SOC
respectively) need to be better aligned in order to determine to what degree
thawed permafrost OC may be destined for long-term burial, thereby
attenuating further global warming.</p
STUDY OF MINIMAL RESIDUAL DISEASE BY MULTICOLOR FLOW CYTOMETRY IN MULTIPLE MYELOMA AFTER AUTOLOGOUS HEMATOPOIETIC STEM CELL TRANSPLANTATION
The frequency of achieving complete remission, as well as overall and disease-free survival, in multiple myeloma (MM) had increased due to introduction in MM treatment regimens of high-dose chemotherapy with following autologous hematopoietic stem cell transplantation (ASCT). However the number of relapses remains high, caused by persistence of residual tumor cells, i.e., the presence of minimal residual disease (MRD). One of the methods for MRD study is multicolor flow cytometry (MFC) where abnormal expression of surface antigens on myeloma plasma cells (PC) is determined. The aim of our study was to investigate the MRD by MFC before and after ASCT, the frequency of MRD-negative status achievement in complete remission (CR) patients at +100 days after ASCT and the frequency of abnormal expressed antigens on myeloma plasma cells. The study included40 MMpatients in CR at +100 days after ASCT and showed that the most common aberrations of PC were: abnormal absence of CD19 and/or CD27, decreased expression of CD38 and abnormal presence of CD56. The proportion of myeloma PCs from all bone marrow cells decreased significantly after ASCT: 20 % of patients acquired MRD-negative status, 10 % had a decrease in the number of abnormal PCs by one fold. Analysis of probability of immunochemical relapse showed that the worst prognosis was in patients with MRD-positive status before and after ASCT. During the MRD monitoring within 3-18 months, MRD-relapses were detected with the subsequent development of immunochemical relapse. The detection MRD in the dynamics is more informative than the study at only one step of therapy. It may help to select more adequate treatment for patient with multiple myeloma in each specific case
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