28,167 research outputs found
Art battle diorama in military-historical museums of USSR and CIS in the second half of 20th century
No full textGorbunov, I. V. Art battle diorama in military-historical museums of USSR
and CIS in the second half of 20th century : monograph / I. V. Gorbunov ; The Ministry of education of the Repablic of Belarus, Educational establishment "Vitebsk State P. M. Masherov University", Chair desing, and crafts and technical graphics. - Vitebsk : Vitebsk State P. M. Masherov University, 2009. - 164 p. : il. - Bibliogr.: p. 99-110. - Biographical dictionary: p. 111-119. - Chronology of development of diorama art (1929-1995): p. 122-132.The monograph represent a complex study of the domestic school Museum and exhibition desing of military-historical museums as art form a complex diorama occupies a dominant place. On the rich illustrative material, the author shows all parties forming dioramas. Gradually, all the elements are investigated artwork, such as modelling-layout plan, lighting, monumental painting, which form the diorama as a complex Museum and exhibition complex-ensemble with 1948 po 1995 gg. intended for researchers, muzeevedov, students of art majors, anyone interested in issues of design and creating monumental-decorative registration of exhibitions and museums
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
The long-wavelength view of GG Tau A: rocks in the ring world
No full textWe present the first detection of GG Tau A at centimetre wavelengths, made with the Arcminute Microkelvin Imager Large Array at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at >6 σrms with an integrated flux density of S16GHz = 249 ± 45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long-wavelength tail of the dust emission from this unusual protoplanetary system. We use an MCMC-based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of Md ~ 0.1 Msun, constrain the dimensions of the emitting region and find that the opacity index at λ > 7 mm is less than unity, implying a contribution to the dust population from grains exceeding ~4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association in combination with the low derived disc mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models
On the binary nature of the γ-ray sources AGL J2241+4454 (= MWC 656) and HESS J0632+057 (= MWC 148)
No full textWe present optical spectroscopy of MWC 656 and MWC 148, the proposed optical counterparts of the gamma-ray sources AGL J2241+4454 and HESS J0632+0 57, respectively. The main parameters of the Halpha emission line (EW, FWHM and centroid velocity) in these stars are modulated on the proposed orbital periods of 60.37 and 321 days, respectively. These modulations are likely produced by the resonant interaction of the Be discs with compact stars in eccentric orbits. We also present radial velocity curves of the optical stars folded on the above periods and obtain the first orbital elements of the two gamma-ray sources thus confirming their binary nature. Our orbital solution support eccentricities e~0.4 and 0.83+-0.08 for MWC 656 and MWC 148, respectively. Further, our orbital elements imply that the X-ray outbursts in HESS J0632+057/MWC 148 are delayed ~0.3 orbital phases after periastron passage, similarly to the case of LS I +61 303. In addition, the optical photometric light curve maxima in AGL J2241+4454/MWC 656 occur ~0.25 phases passed periastron, similar to what is seen in LS I +61 303. We also find that the orbital eccentricity is correlated with orbital period for the known gamma-ray binaries. This is explained by the fact that small stellar separations are required for the efficient triggering of VHE radiation. Another correlation between the EW of Halpha and orbital period is also observed, similarly to the case of Be/X-ray binaries. These correlations are useful to provide estimates of the key orbital parameters Porb and e from the Halpha line in future Be gamma-ray binary candidates
Hundreds of variants clustered in genomic loci and biological pathways affect human height
No full textMost common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits(1), but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait(2,3). The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P<0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways
High-efficient n-i-p thin-film silicon solar cells
No full textIn this thesis we present results of the development of n-i-p thin-film silicon solar cells on randomly textured substrates, aiming for highly efficient micromorph solar cells (i.e., solar cells based on a ?c-Si:H bottom cell and a-Si:H top cell). For the efficiency of n-i-p thin-film silicon solar cells the interfaces between different layers are very important. In this thesis the influence of some important interfaces in the n-i-p configuration solar cells on the solar-cell performance has been studied. The results are presented in a structure that follows the sequence of making an n-i-p solar cell, starting with the textured substrate (Chapter 3), then the development of the ?c-Si:H bottom cell (Chapter 4), the optimization of a-Si:H top cell (Chapter 5), and finally the characterization of the i-p interface of the top cell (Chapter 6). In Chapter 3 the development of textured ZnO:Al (AZO) is presented. Obtaining textured transparent conductive oxide (TCO) using sputtering of AZO layers and subsequent wet etching has already been published in literature and is used as a reference in this thesis. The relation between the etched AZO surface morphology, and the sputtering and wet etching conditions are discussed. The surface of wet-etched AZO films is V-shaped. A high root mean square roughness (?RMS) is achieved with this process and the textured AZO presents high haze in reflection with most of the reflected light located in high angles. Therefore, the n-i-p ?c-Si:H solar cells deposited on this type of substrate have a very high short-circuit current density (Jsc). However, a low open-circuit voltage (Voc) is obtained, because of the relatively high density of defective regions within the ?c-Si:H layers. These defective regions primarily appear in the valleys of the rough V-shaped textured surface. In Chapter 3 we also present a novel way of glass texturing using AZO as sacrificial layer, which we have called the AZO induced texturing process (ZIT process). For this process a AZO layer is deposited onto the glass substrate by sputtering. Then this AZO covered glass is exposed to an etching solution, which contains HF and HNO3. Due to the anisotropic structure of the AZO film the etching of this layer is not homogeneous. Where the AZO etches faster, the glass underneath is exposed to HF sooner. Once some parts of the glass are exposed to the etching solution, the HF starts to etch the glass. When the AZO layer is etched away, the glass texturing process finishes and a rough glass surface is obtained. Therefore, the crucial parameters for this process are: AZO layer thickness and its sputtering temperature, and the composition of the etching solution (in particular the HNO3 to HF concentration ratio). With this process, the ?RMS of the textured glass surface can be tuned between 20 nm and 500 nm. The textured glass surface is U-shaped, on top of which a layer of ?c-Si:H can be deposited with a low density of defective regions as is shown in Chapter 4. In Chapter 3 we also present the development of modulated surface textures (MST) consisting of both large (>10 ?m) and smaller features. The purpose of MST is to obtain a high Jsc, whilst maintaining a high Voc and FF for the ?c-Si:H solar cells. For the MST substrates the large features (> 10 ?m) on the glass were obtained using the so-called ITO induced texturing (IIT) process. Smaller features on top of this IIT structure were obtained by aluminium induced texturing (AIT) process, the ZIT process, or by wet-etching of sputtered AZO. Compared to single textures all the MST substrates have even higher haze in reflection, with a larger fraction of light reflected to higher angles. In Chapter 4 we show results of ?c-Si:H solar cells deposited on the textured substrates developed in Chapter 3. For a 1.2-?m thick ?c-Si:H n-i-p solar cell deposited on the ‘reference’ back reflector (BR) of wet-etched AZO covered with Ag a high short-circuit current density of 24.4 mA/cm2 was obtained. When varying the morphology of the substrates, the Voc and FF of solar cells were not affected for thinner cells, but a rapid drop in Voc and FF was found for thicker intrinsic layers. Using textured glass as substrate obtained with the ZIT process and covered with a Ag layer, high efficiency n-i-p ?c-Si:H solar cells were obtained. We studied the dependence of the n-i-p ?c-Si:H solar-cell performance on the Rs value (defined as Rs = ?RMS/lc, with lc the correlation length) of the textured glass substrates. We found that with increasing Rs the Jsc of the cells increases. The Voc for thin cells decreases, whereas for 3-?m thick solar cells the effect of Rs on the Voc is less obvious. The best-performing solar cell deposited on ZIT textured glass showed high Voc and FF in comparison to cells reported in literature and deposited on state-of-the-art textures, but this gain in electrical performance was counterbalanced by a slightly lower Jsc. This resulted in a conversion efficiency of 10.64% (active area, one best cell, 3.0 ?m thick i-layer) with Voc = 0.533 V, FF = 0.727 and Jsc = 27.47 mA/cm2. Finally, ?c-Si:H n-i-p solar cells were deposited on MST substrates. For these solar cells we found a higher red response in the external quantum efficiency than the reference cell that was fabricated on IIT glass. However, compared to the best ZIT cell this MST cell shows a relatively low red response leading to a Jsc of 26.36 mA/cm2. We think that this lower red response is due to the flattening of the rough surface of the glass when preparing the MST substrate with ZIT process (MST-ZIT). On the other hand, we found from the scanning electron microscopy images that the solar cell deposited on a MST-ZIT process has a very low density of defective regions in the bulk ?c-Si:H layer and gives the highest FF of 0.748 for a 3-?m thick cell. In addition, the Voc remains nearly the same as for the best ZIT cell. These lead to a cell efficiency of 10.49%, which is slightly lower than the efficiency of the best ZIT cell. For a-Si:H solar cells, the recombination rate is highest in the i-p interface region due to the high defect density in this region. As a result the solar-cell performance is suppressed. In Chapter 5 we show results of the effect of H2-plasma treatment before p-layer deposition on the solar-cell performance of n-i-p a-Si:H solar cells. Following this treatment all external solar-cell parameters (i.e., the Voc, FF and Jsc) increase significantly. Dark current-voltage (J-V) characteristics of the solar cells suggest that the current recombination at the i-p interface is lower for H2-plasma treated cells than for a cell without treatment. The FTIR measurement shows that the a-Si:H layer contains a higher hydrogen content after H2-plasma treatment. This a-Si:H layer with higher hydrogen content is around 20 nm thick. Compared to the bulk a-Si:H material this layer has a higher activation energy and lower conductivity. In order to understand the mechanism of the solar-cell performance improvement by the H2-plasma treatment of the i-p interface, we carried out capacitance-frequency (C-f) measurements on n-i-p a-Si:H solar cells. These measurements are presented and discussed in Chapter 6. By applying and further developing the theory of Walter et al.1 on C-f measurements, we have been able to study the energy defect distribution of the i-p interface region. We found that during the capacitance measurement, virtually only the defects near the n-i and i-p interface region contribute to the measured capacitance when a forward bias is applied. When extracting the defect density of states in the i-p interface region from C-f measurements, we find that after a H2-plasma treatment this defect density is decreased and peaks at a deeper energy position. Combining the dark J-V results of these solar cells, the C-f measurements indicate that the lower recombination rate in the i-p region after the H2-plasma treatment is mainly due to the decrease of the defect density in the i-p interface region. Finally, in Chapter 7 of this thesis we present the results of an n-i-p micromorph solar cell made using the results of the development presented in the earlier chapters. This micromorph solar cell has an efficiency of 12.2%. The open-circuit voltage is 1.382 V, the fill factor is 0.72, and the short-circuit current density for the top a-Si:H cell is 12.2 mA/cm2 and 13.1 mA/cm2 for the bottom ?c-Si:H cell. The main conclusions of this thesis and a general outlook for further enhance the efficiency of thin-film silicon solar cell are also presented in Chapter 7.ESEElectrical Engineering, Mathematics and Computer Scienc
Differential equations with maximal monotone operators
No full textThe paper deals with multivalued differential equations in abstract spaces. Nonlocal conditions are assumed. The model includes an m-dissipative multioperator which generates an equicontinuous, not necessarily compact, semigroup. The regularity of the nonlinear term also depends on the Hausdorff measure of noncompactness. The existence of integral solutions is discussed, with a topological index argument. A transversality condition is required. The results are applied to a partial differential inclusion in a bounded domain in R n with nonlocal integral conditions. The model also includes an m-dissipative but not necessarily compact semigroup generated by a suitable subdifferential operator. (c) 2024 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http:// creativecommons .org /licenses /by -nc -nd /4 .0/)
Self-archiving practice and the influence of publisher policies in the social sciences
No full textAuthors in different disciplines exhibit very different behaviours on the so-called ‘green’ road to open access, i.e. self-archiving. This study looks at the self-archiving behaviour of authors publishing in leading journals in six social science disciplines. It tests the hypothesis that authors are self-archiving according to the norms of their respective disciplines rather than following self-archiving policies of publishers, and that, as a result, they are self-archiving significant numbers of publisher PDF versions. It finds significant levels of
self-archiving, as well as significant self-archiving of
the publisher PDF version, in all the disciplines
investigated. Publishers’ self-archiving policies have
no influence on author self-archiving practice
Correction to: Analysing the determinants of Italian university student mobility pathways, (Genus, (2021), 77, 1, (34), 10.1186/s41118-021-00146-2)
No full textFollowing the publication of the original article (Columbu et al., 2021) we were informed that the authors’ given and family names had unfortunately been interchanged. The author names have been corrected in the author list of this Correction and updated in the original article
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