Anthropogenic pressures decrease structural complexity in Caucasian forests of Iran

Ecoscience ◽  
2021 ◽  
pp. 1-11
Author(s):  
Kiomars Sefidi ◽  
Carolyn A. Copenheaver ◽  
Seyed Mohammad Moein Sadeghi
Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 959 ◽  
Author(s):  
Miriam García-Oliva ◽  
Ángel Pérez-Ruzafa ◽  
Georg Umgiesser ◽  
William McKiver ◽  
Michol Ghezzo ◽  
...  

The Mar Menor lagoon has been subjected to high anthropogenic pressures. Among them, in the early 1970s, dredging and enlargement of one of the inlets to make a navigable channel has had strong consequences on the hydrology, ecology, and fisheries of the lagoon. In recent years, changes in agricultural practices have induced an eutrophication process, leading to loss of water quality. As a solution, some management proposals have included dredging of the inlets in order to increase the water renewal. However, these proposals did not take into account the negative effects of previous experiences nor the consequences on environmental conditions of the lagoon and therefore on biological processes. The purpose of this work is to assess the effect that proposed mitigation measures, could have on the hydrodynamic conditions and discuss its possible ecological consequences. A three-dimensional (3D) numerical model has been used to simulate the lagoon under different dredging scenarios, covering different dredging depths and extensions. The simulated current fields and fluxes through the inlets, as well as water renewal times have been compared for the different scenarios. It is found that some of the considered scenarios take the system beyond the threshold of sustainability, where the modified current dynamics could affect sediment transport, beach dynamics and fishing capacities in a significant way. Water exchange with the Mediterranean is also strongly affected, with consequences for species connectivity, and a homogenization of the water renewal times that could lead to loss of ecosystem heterogeneity and structural complexity. The study demonstrates the utility of numerical models as effective tools for the management of coastal areas.


Author(s):  
Mariano Paracuellos ◽  
Miguel A. Gómez de Dios ◽  
Leonardo Gutiérrez ◽  
Enrique Moreno-Ostos

el conocimiento de las especies que habitan en un enclave, facilitando su estudio científico, gestión y divulgación ambiental. A pesar de que las albuferas de Adra constituyen uno de los humedales mejor conocidos de España, la información acerca de la composición de sus comunidades biológicas se encuentra muy dispersa. En este trabajo se ha realizado un compendio de todos los taxones citados para las albuferas de Adra a partir de una completa revisión bibliográfica a la que se sumaron referencias inéditas. A los diferentes taxones conocidos se les clasificó según los grupos funcionales y filogenéticos a los que pertenecen, el tipo de hábitat que ocupaban, así como los regímenes de protección y amenaza en los que están incluidos. La relevancia de este trabajo radica en reflejar, en un solo listado, los componentes de la diversidad biológica conocidos, lo cual es de gran utilidad para la gestión del espacio natural protegido. Hasta la fecha se han citado 599 taxones en las albuferas de Adra. Los vertebrados son los que predominaron en cuanto a diversidad, protección legal y grado de amenaza. Por su lado, también destacó el conocimiento acerca de los organismos planctónicos, así como la, según algunos autores, comparativamente alta diversidad de plantas presentes en su conjunto. A pesar de su abundancia, uno de los grupos que presentó una información más limitada fue el de los invertebrados, especialmente los terrestres. Abstract Biological taxonomy plays a central role for the knowledge of the species that inhabit a certain place, facilitating their scientific study, environmental management and social divulgation. Although the coastal lagoon of Albuferas de Adra constitute one of the best studied wetlands of Almería and Spain, the information on the composition of its biological communities is still very dispersed, so that a standardized list of all the taxa cited in the ecosystem becomes necessary. In the present study, a compilation of the taxa hitherto cited for the Albuferas de Adra has been carried out by means of a deep literature search, to which unpublished references contributed by connoisseurs of their environment were also added. The Albuferas de Adra constitutes a wetland located in the delta of the Adra river (Adra, Almería, Iberian southeast), colonized for decades by today’s ubiquitous agricultural greenhouses (Figure 1). Despite the wetland relevant natural values, the current anthropic pressures derived from intensive agriculture in the catchment have promoted a progressive and significant ecosystem degradation. Although the Andalusian environmental administration promotes management strategies to minimize or mitigate these impacts, severe anthropogenic pressures on the wetland still continue. Exclusively, the taxa that were expressly mentioned for the swampy environment of the delta of the Adra river were taken into account, excluding those linked to environments altered by human activity, or those that undoubtedly constituted erroneous citations. The current list complies with the rules of the international nomenclature codes, grouping each taxon, first according to a simplification of Linnaeus’ hierarchical categories and then alphabetically. Whenever possible, in the identification of the different taxa, the species level was reached. The different taxa mentioned in this paper were typified according to their functional and phylogenetic classification, the type of habitat they occupy, as well as the protection and threat catalogues in which they are registered. To date, 599 taxa have been cited in the Albuferas de Adra wetland complex. Vertebrates accounted for the highest number of cited taxa and, in addition, enjoyed the greatest attention in terms of legal protection and threat registry (Figures 2 and 4). A marked tradition on limnological research in the wetland has provided a detailed knowledge on planktonic communities taxonomical composition. Plants, in general, depicted high biodiversity as a consequence of the wetland structural complexity and the increasing presence of adventitious “of edge” species favored by the greenhouses that have invaded the delta (Figure 2). Despite their usual abundance, actually terrestrial invertebrates constitute a less known taxonomical group in the ecosystem (especially the terrestrial ones), although future studies incorporating them are expected to significantly change this picture. Archaea and Fungi have a worse situation, groups totally unknown today in the Adra lagoons (Figures 2 and 3)


Author(s):  
M. Boublik ◽  
G. Thornton ◽  
G. Oostergetel ◽  
J.F. Hainfeld ◽  
J.S. Wall

Understanding the structural complexity of ribosomes and their role in protein synthesis requires knowledge of the conformation of their components - rRNAs and proteins. Application of dedicated scanning transmission electron microscope (STEM), electrical discharge of the support carbon film in an atmosphere of pure nitrogen, and determination of the molecular weight of individual rRNAs enabled us to obtain high resolution electron microscopic images of unstained freeze-dried rRNA molecules from BHK cells in a form suitable for evaluation of their 3-D structure. Preliminary values for the molecular weight of 28S RNA from the large and 18S RNA from the small ribosomal subunits as obtained by mass measurement were 1.84 x 106 and 0.97 x 106, respectively. Conformation of rRNAs consists, in general, of alternating segments of intramolecular hairpin stems and single stranded loops in a proportion which depends on their ionic environment, the Mg++ concentration in particular. Molecules of 28S RNA (Fig. 1) and 18S RNA (not shown) obtained by freeze-drying from a solution of 60 mM NH+4 acetate and 2 mM Mg++ acetate, pH 7, appear as partially unfolded coils with compact cores suggesting a high degree of ordered secondary structure.


Author(s):  
D. Chrétien ◽  
D. Job ◽  
R.H. Wade

Microtubules are filamentary structures found in the cytoplasm of eukaryotic cells, where, together with actin and intermediate filaments, they form the components of the cytoskeleton. They have many functions and show various levels of structural complexity as witnessed by the singlet, doublet and triplet structures involved in the architecture of centrioles, basal bodies, cilia and flagella. The accepted microtubule model consists of a 25 nm diameter hollow tube with a wall made up of 13 paraxial protofilaments (pf). Each pf is a string of aligned tubulin dimers. Some results have suggested that the pfs follow a superhelix. To understand how microtubules function in the cell an accurate model of the surface lattice is one of the requirements. For example the 9x2 architecture of the axoneme will depend on the organisation of its component microtubules. We should also note that microtubules with different numbers of pfs have been observed in thin sections of cellular and of in-vitro material. An outstanding question is how does the surface lattice adjust to these different pf numbers?We have been using cryo-electron microscopy of frozen-hydrated samples to study in-vitro assembled microtubules. The experimental conditions are described in detail in this reference. The results obtained in conjunction with thin sections of similar specimens and with axoneme outer doublet fragments have already allowed us to characterise the image contrast of 13, 14 and 15 pf microtubules on the basis of the measured image widths, of the the image contrast symmetry and of the amplitude and phase behaviour along the equator in the computed Fourier transforms. The contrast variations along individual microtubule images can be interpreted in terms of the geometry of the microtubule surface lattice. We can extend these results and make some reasonable predictions about the probable surface lattices in the case of other pf numbers, see Table 1. Figure 1 shows observed images with which these predictions can be compared.


1988 ◽  
Vol 19 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Karen E. Pollock ◽  
Richard G. Schwartz

The relationship between syllabic structure and segmental development was examined longitudinally in a child with a severe phonological disorder. Six speech samples were collected over a 4-year period (3:5 to 7:3). Analyses revealed gradual increases in the complexity and diversity of the syllable structures produced, and positional preferences for sounds within these forms. With a strong preference for [d] and [n] at the beginning of syllables, other consonants appeared first at the end of syllables. Implications for clinical management of phonological disorders include the need to consider both structural position and structural complexity in assessing segmental skills and in choosing target words for intervention.


2020 ◽  
Author(s):  
Elizabeth Neumann ◽  
Lukasz Migas ◽  
Jamie L. Allen ◽  
Richard Caprioli ◽  
Raf Van de Plas ◽  
...  

<div> <div> <p>Small metabolites are essential for normal and diseased biological function but are difficult to study because of their inherent structural complexity. MALDI imaging mass spectrometry (IMS) of small metabolites is particularly challenging as MALDI matrix clusters are often isobaric with metabolite ions, requiring high resolving power instrumentation or derivatization to circumvent this issue. An alternative to this is to perform ion mobility separation before ion detection, enabling the visualization of metabolites without the interference of matrix ions. Here, we use MALDI timsTOF IMS to image small metabolites at high spatial resolution within the human kidney. Through this, we have found metabolites, such as arginic acid, acetylcarnitine, and choline that localize to the cortex, medulla, and renal pelvis, respectively. We have also demonstrated that trapped ion mobility spectrometry (TIMS) can resolve matrix peaks from metabolite signal and separate both isobaric and isomeric metabolites with different localizations within the kidney. The added ion mobility data dimension dramatically increased the peak capacity for molecular imaging experiments. Future work will involve further exploring the small metabolite profiles of human kidneys as a function of age, gender, and ethnicity.</p></div></div>


Author(s):  
Theodoros Tsoulos ◽  
Supriya Atta ◽  
Maureen Lagos ◽  
Michael Beetz ◽  
Philip Batson ◽  
...  

<div>Gold nanostars display exceptional field enhancement properties and tunable resonant modes that can be leveraged to create effective imaging tags or phototherapeutic agents, or to design novel hot-electron based photocatalysts. From a fundamental standpoint, they represent important tunable platforms to study the dependence of hot carrier energy and dynamics on plasmon band intensity and position. Toward the realization of these platforms, holistic approaches taking into account both theory and experiments to study the fundamental behavior of these</div><div>particles are needed. Arguably, the intrinsic difficulties underlying this goal stem from the inability to rationally design and effectively synthesize nanoparticles that are sufficiently monodispersed to be employed for corroborations of the theoretical results without the need of single particle experiments. Herein, we report on our concerted computational and experimental effort to design, synthesize, and explain the origin and morphology-dependence of the plasmon modes of a novel gold nanostar system, with an approach that builds upon the well-known plasmon hybridization model. We have synthesized monodispersed samples of gold nanostars with finely tunable morphology employing seed-mediated colloidal protocols, and experimentally observed narrow and spectrally resolved harmonics of the primary surface plasmon resonance mode both at the single particle level (via electron energy loss spectroscopy) and in ensemble (by UV-Vis and ATR-FTIR spectroscopies). Computational results on complex anisotropic gold nanostructures are validated experimentally on samples prepared colloidally, underscoring their importance as ideal testbeds for the study of structure-property relationships in colloidal nanostructures of high structural complexity.</div>


2019 ◽  
Vol 56 (4) ◽  
pp. 365-396
Author(s):  
Debra Higley ◽  
Catherine Enomoto

Nine 1D burial history models were built across the Appalachian basin to reconstruct the burial, erosional, and thermal maturation histories of contained petroleum source rocks. Models were calibrated to measured downhole temperatures, and to vitrinite reflectance (% Ro) data for Devonian through Pennsylvanian source rocks. The highest levels of thermal maturity in petroleum source rocks are within and proximal to the Rome trough in the deep basin, which are also within the confluence of increased structural complexity and associated faulting, overpressured Devonian shales, and thick intervals of salt in the underlying Silurian Salina Group. Models incorporate minor erosion from 260 to 140 million years ago (Ma) that allows for extended burial and heating of underlying strata. Two modeled times of increased erosion, from 140 to 90 Ma and 23 to 5.3 Ma, are followed by lesser erosion from 5.3 Ma to Present. Absent strata are mainly Permian shales and sandstone; thickness of these removed layers increased from about 6200 ft (1890 m) west of the Rome trough to as much as 9650 ft (2940 m) within the trough. The onset of oil generation based on 0.6% Ro ranges from 387 to 306 Ma for the Utica Shale, and 359 to 282 Ma for Middle Devonian to basal Mississippian shales. The ~1.2% Ro onset of wet gas generation ranges from 360 to 281 Ma in the Utica Shale, and 298 to 150 Ma for Devonian to lowermost Mississippian shales.


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