633 research outputs found
Santarém, the paradise of delights: finding Strabo's Moron and its lost island with a new ethymology for Moron
The city of MĆron mentioned by Strabo would be at either SantarĂ©m or ChĂ”es de AlpompĂ©, but not at the Alto do Castelo, in Alpiarça. This was the conclusion of a study by the Deutsches ArchĂ€ologisches Institut in 1982-88. Other authors point to Almeirim, a city eight kilometres south of Alpiarça. Schulten proposes MĆron is the island and castle of Almourol (Tancos). There are at least five hypotheses suggesting where the city of MĆron was. This stems from a restricted understanding of the full meaning of the Greek word kαηΏ. In this article, I clarify the most used meaning of kαηΏ, I propose a new etymology for MĆron and retrieve historical information about the place of an old arm of the river Tagus and of the Lagoon of Almeirim, which pointed me the right place of the island mentioned by Strabo, which was close to MĆron. If my suggestions are correct, then these 2,000-year-old riddles are solved
Clamart, uma solução mais provåvel para a sua etimologia
Esta Ă© a tradução para portuguĂȘs da carta Clamart, a likelier solution for its etymology DOI: 10.20935/al5129, publicada por Academia.edu, com pequenas melhorias gramaticais.
A etimologia de Clamart (Hauts-de-Seine), cidade situada nas proximidades de Paris, atraiu a atenção de vĂĄrios investigadores ao longo dos Ășltimos 150 anos. Ao analisar as suas hipĂłteses, nenhum deles teve em conta a topografia dos locais com toponĂmia semelhante. Um dos investigadores afirmou que Clamart era um topĂłnimo Ășnico, quando, na realidade, existem topĂłnimos relacionados em França e noutros paĂses. Tendo em conta os pontos nĂŁo considerados pelos investigadores anteriores, proponho uma solução etimolĂłgica que corresponde Ă topografia da maioria dos lugares com raiz etimolĂłgica semelhante a Clamart. Em Portugal, este artigo propĂ”e uma nova etimologia para a povoação de Galamares
Mode-selective coupling of coherent phonons to the Bi2212 electronic band structure
Cuprate superconductors host a multitude of low-energy optical phonons. Using
time- and angle-resolved photoemission spectroscopy, we study coherent phonons
in BiSrCaYCuO. Sub-meV
modulations of the electronic band structure are observed at frequencies of
and THz. For the dominant mode at 3.94 THz, the
amplitude of the band energy oscillation weakly increases as a function of
momentum away from the node. Theoretical calculations allow identifying the
observed modes as CuO-derived phonons. The Bi- and Sr-derived
modes which dominate Raman spectra in the relevant frequency range are
absent in our measurements. This highlights the mode-selectivity for phonons
coupled to the near-Fermi-level electrons, which originate from CuO
planes and dictate thermodynamic properties.Comment: 7 pages, 3 figure
Recommended from our members
Linkages among land use, riparian zones, and uptake and transformation of nitrate in stream ecosystems
Land use alters the physical and biological structure of stream ecosystems and potentially alters their capacity to process nitrogen (N), an essential nutrient that has nearly doubled in abundance on the biosphere
during the past century from human activities. In this dissertation, I quantified uptake and transformation of nitrate (NOââ») in small (†third-order) streams and related these dynamics to aquatic ecosystem processes, including primary production and organic matter decomposition, and attributes of riparian zone structure and vegetation composition. I also analyze patterns of stream NOââ» processing among three classes of adjacent land use practices (forest, agriculture, and urban).
In Chapter 2, ambient rates of NOââ» uptake and transformation were measured with 24-hr releases of Âčâ”N-labeled NOââ» in nine stream reaches in the Willamette River Basin of western Oregon during summer low flow (July â
August). Three reaches each were surrounded by forested, agricultural or urban land use. After standardizing reaches to a 500-m length, I estimated that â„ 20% of tracer Âčâ”NOââ» was taken up by detrital and autotrophic biomass in eight of the reaches. In the remaining stream, which had the largest discharge (120 L sâ»Âč) in this study, only 8% of the tracer was taken up in 500 m. Tracer labeling of detritus and autotrophic biomass and a positive correlation (rs=0.81) of uptake with gross primary production suggested that assimilation was the dominant uptake pathway in all streams. Denitrification, dissimilatory reduction of NOââ» to Nâ and NâO gases, composed 3 â 15% of
Âčâ”N budgets over 500 m in two agricultural reaches and in one urban reach dominated by large slowly-turning over pools. However, denitrification was below detection limit at five of the remaining six reaches. This study showed that pathways of stream NOââ» uptake and transformation differed among streams adjacent to three diverse land use practices.
In Chapter 3, I quantified effects of substrate nutritional quality and inorganic N loading (as NOââ») on wood breakdown in western Oregon streams. Short-term (< 2 month) breakdown rates of wood substrates of high nutritional quality (Alnus rubra; red alder) and low quality (Pseudotsuga menziesii; Douglas-fir) increased with dissolved inorganic N (11 to 111 mg N Lâ»Âč) across six streams (p = 0.04), but this relationship was confounded with concurrent
increases in stream temperature. Across the six streams, breakdown rates of red alder were consistently double that of Douglas-fir. A longer-term study (313 d) in a coniferous forest Oregon Cascades stream suggested effects of increased NOââ» availability on wood breakdown became evident after cellulose
and lignin components of woody tissues began to decompose (> 4 months of incubation). Average breakdown rates substrates enriched with NOââ» were higher than those incubated in low NOââ» conditions, but this difference was not statistically significant. However, microbial biofilm respiration rates and activity of two enzymes involved in the breakdown of woody tissues (beta-glucosidase and phenol oxidase) on red alder had significantly greater responses to NOââ» additions than on Douglas-fir after four
months of incubation in the stream. Results suggest that increases in N loading to streams bordered by riparian forests with fast-growing deciduous species could increase wood breakdown rates. On the other hand, increases to N loading may have a smaller effect on wood breakdown in streams surrounded by long-lived coniferous species.
In Chapter 4, I quantified patterns of stream channel and riparian zone attributes for 72 streams equally distributed among forests or grasslands, agriculture, and urban land use practices on from eight major North American
regions. I also related these patterns to stream NOââ» uptake determined from Âčâ”NOââ» tracer releases. Agricultural and urban streams had a simplified channel structure (low width-to-depth ratio, low variation in stream depth, and high stream banks) relative to forest or grassland streams. Agricultural and urban streams also had a significantly smaller median sediment diameter (Dâ
â)
and fraction of benthic sediments composed by silt than in forest and grassland streams. Overstory canopy cover over the channel and in the riparian zone was lowest for agricultural streams but did not significantly differ between forest or grassland streams and urban streams. A multiple regression model showed that stream NOââ» uptake decreased with increasing canopy cover, but also increased with abundance of silt in benthic sediments. This suggested NOââ» uptake was strongly influenced by in-stream primary production and extent of anoxic environments (conducive for denitrification). A multiple regression model for fractional NOââ» uptake by denitrification further supported the concept that extent of anoxic environments influenced overall NOââ» uptake in streams.
Through these studies, I demonstrated that attributes of riparian zone structure and vegetation composition can strongly influence NOââ» uptake and transformation in stream ecosystems by controlling organic matter dynamics. I also have shown that riparian zone attributes vary significantly among three different land use types (forest or grassland, agriculture, and urban). Similarly, pathways of NOââ» uptake and effects of NOââ» on wood breakdown did or were
expected to differ among different land use types / riparian zone characteristics. However, other factors besides riparian attributes, particularly level of nutrient loading, alteration of stream channel physical structure, and basin position of the stream, must be considered in concert when evaluating effects of land use on riparian zone and stream ecosystem structure and
function
Optimal Distinctiveness: The Role of Platform Size and Identity
Recent theoretical advances hold that platforms comprise a second strategic dimension next to size, called identity, which describes the platformâs techno-logical and market scope. Letting go of platform size as the main criterion for platform value opens the possibility for platforms to pursue differentiation strategies with a distinct market positioning. The concept of optimal distinctiveness (OD) implies that differentiation can be optimized so that it maximizes performance. In this paper, we draw on recent OD research in and outside of the field of platforms and elaborate on the role of platform size within the distinctiveness framework. We discuss platform size and identity in the context of OD and suggest propositions for future research. The paper contributes to the management of platforms and OD in platform markets by showing how a platformâs distinctiveness strategy may depend on its size. We contribute to platform management across various platform sizes and to research on OD in platform markets
Whatâs the tally? An Investigation into the Field(s) of Dominant Designs and Platforms
Dominant designs and platforms are two distinct scientific fields in the analysis of innovation of and competition between technologies. Responding to calls for more synthesis in management research, we study the commonalities and differences between the fields surrounding these concepts. To this end, we develop a framework for the comparison of concepts and apply it to dominant designs and platforms. We show that dominant designs and platforms differ most prominently regarding their central mechanisms, their unit and level of analysis, and the timeframe. We will elaborate how they are complementary by developing a research agenda
Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
Using femtosecond time- and angle- resolved photoemission spectroscopy, we
investigated the nonequilibrium dynamics of the topological insulator Bi2Se3.
We studied p-type Bi2Se3, in which the metallic Dirac surface state and bulk
conduction bands are unoccupied. Optical excitation leads to a meta-stable
population at the bulk conduction band edge, which feeds a nonequilibrium
population of the surface state persisting for >10ps. This unusually long-lived
population of a metallic Dirac surface state with spin texture may present a
channel in which to drive transient spin-polarized currents
The scaling or ontogeny of human gait kinetics and walk-run transition: The implications of work vs. peak power minimization
A simple model is developed to find vertical force profiles and stance durations that minimize either limb mechanical work or peak power demands during bipedal locomotion. The model predicts that work minimization is achieved with a symmetrical vertical force profile, consistent with previous models and observations of adult humans, and data for 487 participants (predominantly 11â18âŻyears old) required to walk at a range of speeds at a Science Fair. Work minimization also predicts the discrete walk-run transition, familiar for adult humans. In contrast, modeled peak limb mechanical power demands are minimized with an early skew in vertical ground reaction force that increases with speed, and stance durations that decrease steadily with speed across the work minimizing walk-run transition speed. The peak power minimization model therefore predicts a continuous walk-run gait transition that is quantitatively consistent with measurements of younger children (1.1â4.7âŻyears) required to locomote at a range of speeds but free to select their own gaits
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