Search results for "wall"
showing 10 items of 970 documents
The functional significance of colour polymorphism in the European common wall lizard (Podarcis muralis)
2021
Colour polymorphisms, the coexistence of two or more colour morphs of a species within a population, have long fascinated evolutionary biologists interested in the mechanisms generating and maintaining phenotypic variation in nature. The functional significance of colour polymorphisms (i.e. their adaptive value) is often linked to the selective mechanisms responsible for their maintenance over time. In lizards, the hypothesis that colour morphs may reflect alternative reproductive strategies involving differential sociosexual behaviour and/or alternative reproductive strategies has come to dominate the field. Wall lizards (family Lacertidae, genus Podarcis), with several geographically dist…
Deformation and fluid flow in the Huab Basin and Etendeka Plateau, NW Namibia
2016
Abstract The Lower Cretaceous Twyfelfontein sandstone formation in the Huab Basin in NW Namibia shows the effects of volcanic activity on a potential reservoir rock. The formation was covered by the Parana-Etendeka Large Igneous Province shortly before or during the onset of South-Atlantic rifting. Deformation bands found in the sandstone trend mostly parallel to the continental passive margin and must have formed during the extrusion of the overlying volcanic rocks, indicating that their formation is related to South-Atlantic rifting. 2D-image porosity analysis of deformation bands reveals significant porosity reduction from host rock to band of up to 70%. Cementation of the sandstone, lin…
On the formation of maars
1973
The Pleistocene maars in the Eifel region of Germany, and Massif Central in France, formed when fissures opened at the bottom of older valleys allowing stream water to pour down them and come into contact with rising magma. The resulting phreato-magmatic eruptions gave rise to both base surge and air-fall deposits. Spalling of wall rock at depth enlarged the fissure into an eruption chamber. Subsidence along a ring fault into the eruption chamber accounts for the larger crater cut into the country rocks. The volume relationship between the crater excavated, the ejected pyroclastic debris of the rim and the volume below the floor of the crater, indicates that the volume of the maar ejecta is…
Comparative tests on different multi-electrode arrays using models in near-surface geophysics
2008
In this paper, the response of different synthetic models to geoelectrical multi-electrode surveys is studied. The models considered are related to two main problems, which are very common in geophysical research regarding hydrogeology and engineering. The first class of models represents buried walls, similar archaeological remains or remains of buried foundations; the other class corresponds to a sea-water intrusion of a fresh water aquifer, which is generally studied in hydrogeophysics. A set of 2D simulations, starting from the synthetic models, was carried out to compare the behaviour of the different arrays when acquiring measurements of electrical resistivity tomography. For each mod…
Mur berliński jako granica i linia frontu w czasach zimnej wojny
2018
Celem artykułu jest prezentacja okoliczności budowy, a następnie funkcji pełnionych w czasach zimnej wojny przez mur berliński. Mur został wzniesiony w 1961 r. i stanowił efekt kulminacji konfliktu między ZSRR i aliantami zachodnimi. Władzom w NRD zależało na jego budowie, aby zatrzymać emigrację ludności z Niemiec Wschodnich do Berlina Zachodniego, a następnie do RFN. Po 2015 r. na granicach wielu państw europejskich także budowane są mury, mające uniemożliwić wjazd imigrantów, szczególnie nielegalnych. W tym kontekście warto przyjrzeć się funkcjom pełnionym przez mur berliński, w tym funkcji: politycznej, strategicznej, ekonomicznej, społecznej, symbolicznej i kulturotwórczej. Na podstawi…
Activation of Grapevine Defense Mechanisms: Theoretical and Applied Approaches
2011
part 4.; International audience; Grapevine, as other plants, possesses an innate immune system that usually prevents infection by pathogens. General elicitors are compounds of different biochemical families capable of inducing plant defense reactions. In grapevine, the cascade of defense events induced by elicitors has been studied among others in cell suspensions. The perception of the elicitor triggers signaling events that allow the activation of defense genes encoding PR proteins and other proteins involved in phytoalexin production and cell wall reinforcement. The grapevine phytoalexins resveratrol and derivated compounds have been largely studied. In addition to their antimicrobial ac…
Surface and interface effects on the current-voltage characteristic curves of multiwall carbon nanotube-Si hybrid junctions selectively probed throug…
2021
The possibility to increase the efficiency of photovoltaic (PV) cells based on hybrid carbon nanotube (CNT)–Si heterojunctions is related to the ability to control the chemical properties of the CNT–Si interface and of the CNT bundle layer. In spite of the encouraging performances of PV cells based on multiwall (MW) CNT, so far few efforts have been made in the study of this device compared to single wall (SW) CNT–Si interfaces. Here, surface and interface effects on the current–voltage characteristic curves of MW CNT–Si hybrid junctions are investigated through exposure to HF vapors and to 10 ppm-NO2 and compared to the effects detected in SW CNT–Si junctions. Quite similar results in term…
Contributo alla conoscenza delle proprietà termofisiche delle murature storiche palermitane
2014
This paper presents the preliminary findings of in situ measurements of thermal transmittance taken in a monumental complex in Palermo. The objective of energy efficiency, one of the main aspects of sustainable construction, is now relevant also for historic architecture. The research aims at analysing the energy performance of the stone walls of the complex, characterized by various thickness, age and construction features. Measurements are taken in accordance with the international standard ISO 9869:1994. The U-values so obtained are compared with tabular data from the Italian standard UNI/TS 11300-1:2008 and with values calculated following the UNI EN ISO 6946:2008. Nine preliminary meas…
The Benign Side of the Abdominal Wall: A Pictorial Review of Non-Neoplastic Diseases.
2022
The abdominal wall is the location of a wide spectrum of pathological conditions, from benign to malignant ones. Imaging is often recommended for the evaluation of known palpable abdominal masses. However, abdominal wall pathologies are often incidentally discovered and represent a clinical and diagnostic challenge. Knowledge of the possible etiologies and complications, combined with clinical history and laboratory findings, is crucial for the correct management of these conditions. Specific imaging clues can help the radiologist narrow the differential diagnosis and distinguish between malignant and benign processes. In this pictorial review, we will focus on the non-neoplastic benign mas…
The Neoplastic Side of the Abdominal Wall: A Comprehensive Pictorial Essay of Benign and Malignant Neoplasms
2023
Abdominal wall neoplasms are usually benign and, in the majority of these cases, no further work-up or treatment is indicated. The percentage of malignant abdominal neoplasms, however, is not negligible. Radiologists play a pivotal role in identifying imaging features that should favor malignancy, including larger lesion size, edema, neurovascular involvement, and peripheral or inhomogeneous dynamic enhancement, thus indicating to the clinician the need for further work-up. Histopathology is the reference standard for the characterization of abdominal wall neoplasms. In patients undergoing surgery, radiological assessment is needed to guide the surgeon by providing a comprehensive anatomic …