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- Soininen, E.M., et al.
(author)
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Location of studies and evidence of effects of herbivory on Arctic vegetation: a systematic map
- 2021
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In: Environmental Evidence. - : BioMed Central (BMC). - 2047-2382. ; 10:1
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Journal article (peer-reviewed)abstract
- Background: Herbivores modify the structure and function of tundra ecosystems. Understanding their impacts is necessary to assess the responses of these ecosystems to ongoing environmental changes. However, the effects of herbivores on plants and ecosystem structure and function vary across the Arctic. Strong spatial variation in herbivore effects implies that the results of individual studies on herbivory depend on local conditions, i.e., their ecological context. An important first step in assessing whether generalizable conclusions can be produced is to identify the existing studies and assess how well they cover the underlying environmental conditions across the Arctic. This systematic map aims to identify the ecological contexts in which herbivore impacts on vegetation have been studied in the Arctic. Specifically, the primary question of the systematic map was: “What evidence exists on the effects of herbivores on Arctic vegetation?”.Methods: We used a published systematic map protocol to identify studies addressing the effects of herbivores on Arctic vegetation. We conducted searches for relevant literature in online databases, search engines and specialist websites. Literature was screened to identify eligible studies, defined as reporting primary data on herbivore impacts on Arctic plants and plant communities. We extracted information on variables that describe the ecological context of the studies, from the studies themselves and from geospatial data. We synthesized the findings narratively and created a Shiny App where the coded data are searchable and variables can be visually explored.Review findings: We identified 309 relevant articles with 662 studies (representing different ecological contexts or datasets within the same article). These studies addressed vertebrate herbivory seven times more often than invertebrate herbivory. Geographically, the largest cluster of studies was in Northern Fennoscandia. Warmer and wetter parts of the Arctic had the largest representation, as did coastal areas and areas where the increase in temperature has been moderate. In contrast, studies spanned the full range of ecological context variables describing Arctic vertebrate herbivore diversity and human population density and impact.Conclusions: The current evidence base might not be sufficient to understand the effects of herbivores on Arctic vegetation throughout the region, as we identified clear biases in the distribution of herbivore studies in the Arctic and a limited evidence base on invertebrate herbivory. In particular, the overrepresentation of studies in areas with moderate increases in temperature prevents robust generalizations about the effects of herbivores under different climatic scenarios.
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- Sendova-Vassileva, M, et al.
(author)
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Depth dependence of photoluminescence and chemical bonding in porous silicon
- 1999
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In: Journal of Luminescence. - 0022-2313 .- 1872-7883. ; 80:1-4, s. 179-182
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Journal article (peer-reviewed)abstract
- Porous silicon (PS) is studied by stepwise peeling of the surface layer to clarify the non-uniformity in the photoluminescence (PL) and correlate it with the in-depth chemical bonding and structure of the 30 μm thick layer. The PL intensity grows by an order of magnitude after the peeling off of the first 10 μm and decreases five times in the next 5 μm while the peak maximum position shifts from 730 to 800 nm. X-ray photoelectron spectroscopy (XPS) measurements show that Si–Si and Si–O bonds are present both on the surface and below, and the preferential oxidation state of silicon changes from 3+ and 4+ on the surface to 1+ and 2+ below 10 μm. Using Raman spectroscopy silicon nanocrystals are shown to exist. Their mean size can be estimated at about 3 nm. These results show that the strongest PL comes from a region in the PS layer where silicon nanocrystallites are surrounded by oxides with a low level of oxidation and not from the strongly oxidized surface layer.
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- Zozikov, B, et al.
(author)
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[Intrascrotal nontesticular tumors].
- 1999
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In: Khirurgiia. - 0450-2167. ; 55:2
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Journal article (peer-reviewed)abstract
- This is a review of literature data on rarely met with intrascrotal non-testicular tumors still not well enough clarified in clinical practice. Histologically these tumors derive from: 1. Epididymis. 2. Funiculus spermaticus and/or tunica vaginalis. 3. Tissues within the scrotum (fatty, fibrous, muscular, lymphatic, nervous). 4. Metastases. The individual types of neoplasms, some of them representing casuistic rarity, so far described as sporadic observations in the pertinent literature, are discussed. Adenomatoid tumor of epididymis and rhabdomyosarcoma are the most frequently encountered. Clinically paratesticular tumors do not lend themselves to differentiation from the ones involving the testis regardless of the fact that for some of them data on specific laboratory and serum or tissue tumor markers have been duely reported. Diagnosis is made histologically following operative management--orchiepididymectomy. According to histological pattern, if necessary the treatment proceeds with radio- or chemotherapy. Finally, two personal observations are described.
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