Opposite Margin Research Articles

Temporal trends in sand bars and water bodies on the right side of the world's largest fluvial island - Javaés River

Bananal Island is the largest river island in the world, located in the Araguaia River basin in central-western Brazil. Studies on the Araguaia River have shown that changes in the main channel are linked to the increase in sediment input due to agricultural expansion in the Cerrado. However, very little is known about the Javaés River, on the opposite margin of Bananal Island. This study analyzed the temporal trends of sand bars and water masses in the Javaés River from 1985 to 2021. Annual mosaics of Landsat images were generated to identify the classes of water masses and sand bars. The Mann Kendall and Sen's Slope tests were used to identify trends and statistical significance of changes over time. The results indicated an increase of 57% (6.5 km²) in the areas of sand bars and a reduction of 39% (15.2 km²) in water bodies. The tests revealed significant trends with an increase in bars and a decrease in water bodies. It was observed that changes in the distribution and rates of regional precipitation, along with the expansion of anthropogenic occupation, are contributing to an increase in sediment input, in a cascade effect, affecting the balance between erosion and deposition in the Javaés River.

Orogenic gold belt overlap in the eastern Peninsular Ranges batholith: La Rumorosa mining area, Baja California, Mexico

Gold deposits in the La Rumorosa mining area (Baja California), located in the eastern Peninsular Ranges batholith (PRB), consist of auriferous quartz-(carbonate) veins hosted by brittle-ductile shear zones within metamorphic and synorogenic plutonic rocks. A combination of two geochronology methods, U–Pb zircon dating of country rocks and 40Ar/39Ar dating of hydrothermal and metamorphic white micas, along with the structural characterization of the main orebodies, has allowed the differentiation of two gold mineralization events in the study area. The oldest deposit (>93 Ma) is related to the main compressive phase of the PRB construction (∼110‒90 Ma) and is part of the yet poorly known Peninsular Ranges orogenic gold belt. Two other gold deposits were dated at ∼77 and 75 Ma, an age span that approximately corresponds to the beginning of the Laramide tectonism instead. Therefore, these deposits can be considered the oldest and westernmost constituents of the Caborca orogenic gold belt (∼69‒36 Ma), formerly recognized in the neighboring states of Sonora, Arizona, and the southeastern tip of California. Furthermore, the Laramide gold deposits at La Rumorosa are contemporaneous with the first generation (∼76‒74 Ma) of copper porphyries in the southern North American Cordillera belt, which are also situated on the opposite margin of the Gulf of California-San Andreas fault system. Both gold and copper deposits show an eastward migration during the early Upper Cretaceous, similar to the well-documented shift in magmatism and deformation in the region, albeit occurring asynchronously. The apparent continuous formation of orogenic gold deposits in southwestern North America from the middle Cretaceous to the Eocene, resulting from the strong convergence between the subducted Farallon plate and the continent, suggests a connection between the Peninsular Ranges and Caborca gold belts. We surmise that both of these orogenic gold belts may form part of a large metallogenic province in western Mexico.

Secondary single-piece toric posterior chamber intraocular lens fixation

The intended axis of fixation of a dislocated TECNIS single-piece toric posterior chamber intraocular lens (PC IOL) is identified, and a marker is placed 40 degrees counterclockwise to this axis. A polypropylene suture on a straight needle is passed 2.5 mm posterior to the limbus through a scleral flap at this meridian and into the bore of the needle inserted through a paracentesis at the opposite margin, then the needle is retracted, reinserted, and captured through a second needle inserted through the scleral flap adjacent to the first suture pass, leaving a loop of suture outside of the paracentesis. The haptic of the PC IOL is externalized through another paracentesis made at the scleral flap margin. The loop of suture is pulled into the anterior chamber and out of the latter paracentesis. A cow-hitch knot is fastened around the haptic, which is then repositioned, while the suture is tightened until the PC IOL is in its final aligned position.

Accretionary orogenesis triggered by collision across continent distance: Evidence from the Proto‐Tethyan West Kunlun, China

AbstractProto‐Tethyan orogenic processes prior to the late Ordovician collision remain unclear. Both whole‐rock La/Yb‐ and zircon Eu/Eu*‐based crustal thickness proxies along with petrological and geological observations were used to reconstruct mountain‐building history for the West Kunlun orogenic belt, China, over the span of Early Palaeozoic. Here, we demonstrate that Proto‐Tethyan West Kunlun crust has observed significant accretionary orogeneses at 520–480 Ma and 480–450 Ma and collisional orogenesis at 450–400 Ma. The 520–480 Ma accretionary orogenesis in West Kunlun together with the coeval Delamerian accretionary contractional orogenesis in eastern Australia were simultaneously induced by continent‐continent collisions that welded the Gondwana landmass. Ca. 440 Ma docking of Tarim and its eastern neighbouring blocks along the northern margin of Gondwana in turn triggered the Lachlan accretionary orogenesis along the opposite margin. This study highlights that accretionary orogenesis could be a manifestation of far‐field compressional stress from continent‐continent collision.

Assessment of eutrophication through ecological indicators at the entrance of a tropical urbanized estuary

Dissolved nutrients, phytoplankton biomass and other ancillary variables, were obtained at two sub-embayments at the entrance of Guanabara Bay (Rio de Janeiro, Brazil) and a composite trophic status index (TRIX) was used to assess the water quality of the study area. The role of bottom sediments in nutrient dynamics was also investigated through the evaluation nutrients, phytoplankton biomass and other sedimentary variables, since this compartment acts as a geological record of anthropogenic input. Jurujuba Sound, at the east margin, and Flamengo-Botafogo Sounds, at the western margin, were sampled during neap and spring tides in the dry season. Signs of eutrophication were detected through the extreme variations of dissolved oxygen concentrations at both margins, being more accentuated at Jurujuba Sound (2.20-14.07 mg.l-1). Dissolved inorganic nitrogen was elevated at both margins and mostly composed of ammonium, surpassing 87% at Flamengo Botafogo Sounds, which suggests a continued input of raw sewage at the western margin of the bay. TRIX revealed poor water quality for most stations at the study area, varying from 4.53 to 7.29 at Jurujuba Sound and from 5.67 to 7.87 at Flamengo-Botafogo Sounds. The increase of TRIX from neap to spring tide was registered at both margins, revealing decrease of water quality. The differences in grain size between both margins played a key role in nutrient dynamics, with predominance of fine sediments at Jurujuba Sound and coarser particles at the opposite margin. Accumulation of high concentrations of TOC (0.87-6.57%) and inorganic phosphorus (154.34-1516.82 µg.g-1) were favored by the predominance of fine sediments at Jurujuba Sound. The assessment of eutrophication in water column and bottom sediments revealed the maintenance of this process at the entrance of Guanabara Bay sustained by the recurrent anthropogenic input, what demands urgent action from public policies to mitigate this situation.

Wall shear stress in open channel flow using different configurations of groynes

ABSTRACT The effects of groyne geometry and arrangement on wall shear stress in a straight channel are studied by means of Computational Fluid Dynamics (CFD) software. Two- and three-dimensional models including pressure-velocity coupling scheme SIMPLE and the equations are used to show that the 2D model can adequately predict flow in comparison to 3D cases, reducing computing time considerably. The numerical procedure is validated by comparing numerical results with experimental measurements obtained from a laboratory-scale glass open channel with no bed sediments. Operating parameters are calculated by the Froude similarity study of a real-scale channel situation. The validated scheme is used to analyze the wall shear stress behavior in terms of groyne geometry and, in the case of multiple configurations, of the optimal distance between them. In all the considered settings, the presence of groynes causes an increase in the wall stress on the opposite margin and a decrease in the margin of groyne location. The shorter the groyne length, the smaller the rise on the shear stress on the other margin. The most significant reduction of the wall shear stress on the groyne margin is obtained with three groyne configurations.

Three-dimensional reconstruction and measurement of fuel assemblies for sodium-cooled fast reactor using linear structured light

Three-dimensional reconstruction and measurement of sodium-cooled fast reactor fuel assemblies has played an important role in evaluating the deformation and mechanical damage of sodium-cooled fast reactor fuel assemblies and judging whether they can continue to be used. In this paper, a three-dimensional reconstruction and measurement method for the fuel assemblies of sodium cooled fast reactor based on linear structured light with radiation resistance is proposed.Then, the measurement error is corrected by the refractive correction model, which is introduced by radiation resistant glass. What’s more, a contour splicing method to unify the data obtained by four linear structured light measuring instruments into a world coordinate system is put forward.The effect of radiation resistant glass on measurement accuracy was tested, and the measurement results are corrected with a correction error of ±0.05 mm.The three-dimensional reconstruction and measurement of a standard part and a simulation component of sodium-cooled fast reactor fuel assembly shows that the method can achieve high-precision 3D reconstruction, and the measurement error of the opposite margin and the diagonal distance of the standard part is less than ± 0.05 mm.

Molecular phylogeny of the Austrolebias/ adloffi/ group (Cyprinodontiformes, Rivulidae), with description of two new endangered and highly endemic species of annual killifishes from the Laguna dos Patos system, southern Brazil.

The Austrolebias adloffi species group encompasses a diverse lineage of annual killifishes that occurs along the Laguna dos Patos/Lagoa Mirim system, in both Brazilian and Uruguayan territories. We herein employ an integrative taxonomy approach to describe two new species of the group, inferring their phylogenetic relationships and evaluating their conservation status. Austrolebias cheffei sp. nov. and Austrolebias lourenciano sp. nov. are herein described from the western portion of the Laguna dos Patos system. Austrolebias cheffei is distinguished from the remaining species of the A. adloffi species group by presenting a yellowish green or yellowish blue dorsal fin, with wide black to dark brown bars extending from the base to the middle portion of the dorsal and anal fins in the males. Austrolebias lourenciano is distinguished from the remaining species of the A. adloffi species group by presenting a yellowish green dorsal fin, with light yellow or light bluish bars forming small triangles, interspersed with small dark brown rows of blotches in the dorsal fin base, and greenish blue anal fin, sometimes with lighter elongated yellowish iridescent blotches, limited to the basal region. According to mitochondrial cytb sequences, both species are reciprocally monophyletic relative to other species of the A. adloffi species group, and present positive barcoding gap values. Interestingly, both new species form a grade that is closely related to Austrolebias aff. minuano 1, an undescribed species that occurs at the opposite margin of the Laguna dos Patos. Among the other evaluated species, A. bagual, A. aff. minuano 1, A. nigrofasciatus, A. pelotapes, A. pongondo, A. arachan, and A. viarius also revealed to be reciprocally monophyletic, whereas A. minuano and A. adloffi revealed to be paraphyletic in regard to A. charrua and A. aff. minuano 2, respectively, and A. nachtigalli is subdivided in two clades, one of which including A. reicherti, which points to the need of a taxonomic review of the group. In addition, we discussed the conservation status of the new species, corrected the type locality of A. pongondo, and provided a dichotomous identification key of the A. adloffi species group.

Competition and the risk of bank failure: Breaking with the representative borrower assumption

AbstractWe examine the relation between intensity of competition in the loan market and risk of bank failure, in a model with adverse selection. As well established, the presence of the two opposite margin and risk‐shifting effects creates conditions for nonmonotonicity: the conventional competition‐fragility view may be challenged at high interest rates. These rates may however be too high to be compatible with oligopolistic equilibrium conditions. The challenging competition‐stability view has been argued in terms of a representative borrower managing the profitability‐safeness trade‐off under moral hazard. However, the representative borrower assumption is not innocuous, playing down by construction the margin effect. The paper considers the adverse selection situation where that trade‐off is managed by banks facing heterogeneous borrowers, and shows analytically, in the case of a trapezoidal distribution of idiosyncratic and systemic risk factors, that the conventional view is always valid.

Geology and thermal maturity of Namurian deposits in the Němčičky Sub-basin as the South-eastern continuation of the Upper Silesian Coal Basin (Czech Republic)

The southernmost documented occurrences of Namurian coal-bearing strata can be found in the Němčičky area, SE Moravia, that is considered to be the southern continuation of the Upper Silesian Coal Basin. Since the south-eastern Moravia belongs to the most prospective areas in terms of hydrocarbon exploration and production in the Czech Republic and Namurian deposits are considered to be one of the potential source rocks, there was a systematic evaluation of the southernmost occurrence of coal-bearing Carboniferous deposits in the Czech Republic during the hydrocarbon exploration within the area with regard to the regional geological setting and thermal maturity. 2D and high-quality 3D seismic surveys were used for a detailed thermal maturation analysis and a determination of the regional situation of heavily faulted/eroded Namurian strata. Cores and cuttings of coal and siltstones were used from 8 boreholes to investigate and measure the vitrinite reflectance; the lithology and petrography definition was also done based on thin sections. All new measurements were compared with archived data and older studies. In the Němčičky Sub-basin, the complete sedimentary succession occurs as part of typical cyclic development, starting with basal conglomerates and followed by sandstones alternating with claystones, siltstones and coal seams of marine and transitional origin. Samples from the Nikolčice-Kurdějov ridge are showing significantly lower vitrinitte reflectance values with respect to their depths than those from the Nesvačilka graben; this fact is supporting the distinctive lateral movement along the western Nesvačilka fault as presumed from the seismic interpretation. Dominant source from “immature” orogen is combined with the source from the “mature” continetal block i.e. opposite margin of the basin. The seismic interpretation shows that the thicknesses of Namurian deposits are not decreasing at all towards the recently deeper positions; accordingly, it is suggested that it is right within this erosionally untouched accommodational space of the Němčičky Sub-basin where we can find the interconnection to the USCB in the north.

Two new species of Melanorivulus (Cyprinodontiformes: Cynolebiidae) from Rio Verde drainage, Upper Rio Paraná basin, Brazil.

Two new species of the genus Melanorivulus are herein described from the middle Rio Verde drainage, upper Rio Paraná basin, Mato Grosso do Sul, Brazil. Both new species are members of the Melanorivulus pictus clade, diagnosed by having ventral process of angulo-articular vestigial and flanks intense greenish blue or greenish golden to purplish blue above anal fin base in males. Melanorivulus nigropunctatus, new species, from wetlands of a small drainage tributary of right side of the Rio Verde, differs from all other congeners by possessing black dots over the head and body in both sexes and pectoral fin orange with a dark grey margin in males. Melanorivulus ofaie, new species, is found in a similar environment, but at the opposite margin of the Rio Verde. It is distinguished by males presenting flank greenish blue to light blue, with seven to nine oblique chevron-like red bars, ventral portion of head whitish with dark brown spots, dorsal fin yellow with two to three transverse broad red oblique stripes and distal region red, anal fin light orangish yellow, basal area light blue with short red bars and distal portion with a dark red margin, and caudal fin yellow or orangish yellow with three to four vertical red bars in the dorsal and middle portions, sometimes with a orange distal margin. Both new species are considered endangered due to the loss and degradation of their habitat.

A bathymetric study to support management plans for La Caimanera coastal lagoon, Gulf of Morrosquillo, Colombia

There are large extensions of coastal lagoons in the Colombian Caribbean. In spite of their renowned environmental and socio-economic importance, these ecosystems have been poorly evaluated. To initiate a process for understanding the biophysical features of the La Caimanera lagoon, bathymetric surveys were conducted on a 25 × 25 m grid approach. Echo sounder and GPS were used to collect the data, which was then analyzed with ArcGIS 9.2 to produce bathymetry maps. A total of 3355 data points indicated an average depth of 1.83 m (SD ± 0.55) with a range of 0.7–5.4 m. Higher and lower values were recorded within the access channel and on the western margin of the lagoon respectively, suggesting that depth distribution was probably related to the interaction of different factors. These factors include the hydrological influence of the entrance channel currents and the micro-catchments of the streams located on the southeast side, along with the possible effects of the survey course selection. Apparently, the dynamic of the streams caused sedimentation on the opposite southwest margin, affecting the environmental quality by siltation and the accumulation of organic matter. Research, monitoring programs, and new management plans are necessary to avoid the deterioration of the ecological goods and services derived from this important local ecosystem.

How water level management affects cladoceran assemblages in lakes lateral to a reservoir

This study analysed the effects of induced water level depletion for macrophyte control in a tropical reservoir on the cladoceran fauna of two differentially connected lateral lakes. One lake, Pedra Branca, is located in the right margin and has a narrow connection to the main river–reservoir channel as well as a higher proportion of submerged macrophytes. On the opposite margin is Lake Guaritá, which is shallower and has a wider connection. Samples were collected over 16 consecutive months, including periods before, during and after depletion. Both lakes showed closely related trends in depth, pH, DO, conductivity, chlorophyll, temperature, suspended matter, phosphorus, nitrogen, silicate and ammonium variation, although a wider amplitude in variation was observed in Pedra Branca. This lake also had higher cladoceran diversity and a predominance of Chydoridae, whereas Bosminidae prevailed in Guaritá. Depletion caused a reduction in richness and an increase of Bosminidae in both lakes, although this was more pronounced in Pedra Branca. The management moderately affected both lakes but continuous application of this procedure may lead to a shift in the system steady-state and a loss of diversity that could be difficult to reverse.

A review of the leafuopper genus <i>Jikradia</i> with descripíions of four new spedes (Homoptera: Cicadellidae)

Se describen e ilustran cuatro especies nuevas de Jikradia Nielson: J. mexicana (México) J. longa (Costa Rica, Guatemala, México), J. zurquiensis (Costa Rica) y J.lizanoi (Costa Rica). El trabajo inlcuye una clave ilustrada para todas las subespecies, con base en los aparatos genitales masculinos.

Incidental Total Necrosis of a Successful Flap Due to a Secondary Operation after One Year

Incidental Total Necrosis of a Successful Flap Due to a Secondary Operation after One Year

Refuting the technological cornerstone of the Ice-Age Atlantic crossing hypothesis

The “North Atlantic Ice-Edge Corridor” hypothesis proposes that sometime during the Last Glacial Maximum, roughly 26,500–19,000 years ago, human populations from southern France and the Iberian Peninsula made their way across the North Atlantic and colonized North America. A key element of that hypothesis is the apparent similarity between stone-tool-production techniques of Solutrean peoples of Western Europe and Clovis and purportedly pre-Clovis peoples of eastern North America, most especially the supposed intentional use of “controlled overshot flaking,” a technique for thinning a bifacial stone tool during manufacture. Overshot flakes, struck from prepared edges of the tool, travel across the face and remove part of the opposite margin. Experimental and archaeological data demonstrate, however, that the most parsimonious explanation for the production of overshot flakes is that they are accidental products created incidentally and inconsistently as knappers attempt to thin bifaces. Thus, instead of representing historical divergence, overshot flakes in Clovis and Solutrean assemblages mark convergence in the use of the same simple solution for thinning bifaces that produced analogous detritus.

Genetic structure, phylogeny, and biogeography of Brazilian eyelid-less lizards of genera Calyptommatus and Nothobachia (Squamata, Gymnophthalmidae) as inferred from mitochondrial DNA sequences

Calyptommatus and Nothobachia genera of gymnophthalmid lizards are restricted to sandy open habitats on São Francisco River margins, northeastern Brazil. Phylogenetic relationships and geographic distribution of the four recognized species of Calyptommatus were analyzed from partial mitochondrial cyt b, 12S, and 16S rRNA genes sequencing, taking allopatric populations of the monotypic Nothobachia ablephara as the outgroup. In Calyptommatus a basal split separated C. sinebrachiatus, a species restricted to the eastern bank of the river, from the three other species. In this clade, C. confusionibus, found on western margin, was recovered as the sister group of the two other species, C. leiolepis and C. nicterus, from opposite margins. According to approximate date estimations, C. sinebrachiatus would have separated from the other congeneric species by 4.4–6.5 my, and C. nicterus, also from eastern bank, would be diverging by 1.8–2.6 my from C. leiolepis, the sister species on the opposite margin. C. confusionibus and C. leiolepis, both from western sandy areas, would be differentiating by 2.8–5.0 my. Divergence times of about 3.0–4.0 my were estimated for allopatric populations of Nothobachia restricted to western margin. Significant differences in 16S rRNA secondary structure relatively to other vertebrates are reported. Distinct evolutionary patterns are proposed for different taxa in those sandy areas, probably related to historical changes in the course of São Francisco River.

Immunohistochemical analysis of P-Selectin as a possible marker of vitality in human cutaneous wounds

Immunohistochemical detection of mediators of inflammation, such as P-Selectin, has been proposed to assess vitality of wounds. Forty-five incised cutaneous wounds (24 vital, 14 post-mortem, seven with induced autolysis/putrefaction) were immunostained with antibodies against P -Selectin and CD31. The percentage of stained lumina for P-Selectin out of the total of CD31 positive vessels (P-S/CD31 index) was calculated at both edges of every specimen. In vital samples, the P-S/CD31 index ranged from 10.7% to 71.4% at the wound edge, and was 12.5–58.8% for the opposite margin, with a ratio between both indices of 0.37–1.77 (mean: 0.94). In post-mortem cases, the index ranged from 22.5% to 69.2% at the wound edge, and was 28–89.5% at the opposite margin, with a ratio between both indices of 0.76–1.9 (mean: 0.96). Differences between ratios were not statistically significant and thus precluded any assessment of vitality. The analysis of P-Selectin/CD31 immunoreactivity in skin wounds was not useful for the diagnosis of vitality when evaluating both edges for each specimen. Moreover, P-Selectin has been detected in post-mortem injuries and it is not specific to vital injuries. Microscopic evaluation becomes difficult after autolysis/putrefaction.

Study of the potential spermatogonial stem cell compartment in dogfish testis, Scyliorhinus canicula L.

In the lesser-spotted dogfish (Scyliorhinus canicula), spermatogenesis takes place within spermatocysts made up of Sertoli cells associated with stage-synchronized germ cells. As shown in testicular cross sections, cysts radiate in maturational order from the germinative area, where they are formed, to the opposite margin of the testis, where spermiation occurs. In the germinative zone, which is located in a specific area between the tunica albuginea of the testis and the dorsal testicular vessel, individual large spermatogonia are surrounded by elongated somatic cells. The aim of this study has been to define whether these spermatogonia share characteristics with spermatogonial stem cells described in vertebrate and non-vertebrate species. We have studied their ultrastructure and their mitotic activity by 5'-bromo-2'-deoxyuridine (BrdU) incorporation and proliferating cell nuclear antigen (PCNA) immunodetection. Additionally, immunodetection of c-Kit receptor, a marker of differentiating spermatogonia in rodents, and of alpha- and beta-spectrins, as constituents of the spectrosome and the fusome, has been performed. Ultrastructurally, nuclei of stage I spermatogonia present the same mottled aspect in dogfish as undifferentiated spermatogonia nuclei in rodents. Moreover, intercellular bridges are not observed in dogfish spermatogonia, although they are present in stage II spermatogonia. BrdU and PCNA immunodetection underlines their low mitotic activity. The presence of a spectrosome-like structure, a cytological marker of the germline stem cells in Drosophila, has been observed. Our results constitute the first step in the study of spermatogonial stem cells and their niche in the dogfish.

An Arthroscopic Hip Documentation Form

Hip arthroscopy is becoming increasingly popular. A simple, precise, and practical means of recording arthroscopic findings will be useful for diagnostic, research, and audit purposes. Basic principles of cartography exist to produce two-dimensional paper representations of our spherical planet. We used the same principles to produce a two-dimensional map of the acetabulum and femoral head. The resulting hip diagram shows the acetabulum as viewed from the side and the femoral head as viewed from above. The ligamentum teres is attached to the medial margin of the head. The head–neck junction and part of the femoral neck is shown at the opposite margin of the ligamentum teres. The hip documentation form is simple, precise, and accurate. We use it to record our findings at hip arthroscopy, which we have used to assist us in our practice.