Journal articles on the topic 'Shelly ridges'
To see the other types of publications on this topic, follow the link: Shelly ridges.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Shelly ridges.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Kowalewski, Michal, Karl W. Flessa, and Jill A. Aggen. "Taphofacies analysis of recent shelly cheniers (beach ridges), northeastern baja california, Mexico." Facies 31, no. 1 (December 1994): 209–41. http://dx.doi.org/10.1007/bf02536940.
Full text
2
Jeanson, Matthieu, Samuel Etienne, and Antoine Collin. "Wave attenuation and Coastal Protection by Shelly Ridges: Mont-Saint-Michel Bay, France." Journal of Coastal Research 75, sp1 (March 3, 2016): 398–402. http://dx.doi.org/10.2112/si75-080.1.
Full text
3
Kidwell, Susan M. "Internal anatomy and skeletal taphonomy of marine sequences: variation with subsidence." Paleontological Society Special Publications 6 (1992): 165. http://dx.doi.org/10.1017/s2475262200007255.
Full textAbstract:
Skeletal concentrations are common foci for paleontologic collecting, yet vary widely in their expected levels of taphonomic bias, particularly temporal resolution and biological fidelity. Basic concentration types include: (1) simple event-concentrations composed of anything from autochthonous-census, entirely exotic, or entirely remanié assemblages (e.g., shelly tempestites, shell-lined burrows); (2) composite concentrations of many stacked to complexly amalgamated events, accumulated in normal to expanded thickness (e.g., bioherms, shell banks & fans); (3) stratigraphically condensed hiatal concentrations having an even greater minimum degree of assemblage-level taphonomic bias (e.g., transgressive shelly sands, sediment-starved bone beds); and (4) lag-concentrations formed by erosion/corrosion of significant section and composed typically of highly culled and time-disordered skeletal material. Detailed field study of three temperate to subtropical basins in North America and reconnaissance of other basins at similar and lower paleolatitudes indicate that these four concentration types are distributed systematically within unconformity-bounded sequences and, moreover, that marine sequences vary qualitatively both in their stratigraphic anatomy (e.g. Van Wagoner et al., 1990; Einsele & Bayer, 1991) and skeletal taphonomy as a function of long-term subsidence.I. Basins of moderate subsidence (total 10's cm/ka maintained over 1–10 ma) are characterized by “textbook” sequences composed of discrete upward-shallowing parasequences in transgressive and highstand/regressive marine phases. Taphonomically, sequences in these settings typically contain a variety of concentration types, and therefore require careful taphonomic differentiation. In the shale-rich Cretaceous Ostracode Zone (Alberta foreland basin; Banerjee & Kidwell, 1991), for example, composite shell beds mark the tops of parasequences near the basin margin, event-beds of granulated shell mark the bases of parasequences further offshore, and diagenetically complex, shell-poor hiatal limestones mark maximum flooding surfaces in the most distal areas.II. Basins of high subsidence (total 100's cm/ka maintained over ≥1ma) are typically characterized by expanded sequences with vague parasequences; sedimentary cyclicity is linked more clearly to local tectonism and autocyclic environments than to eustasy. Taphonomically, these records are dominated by comparatively straightforward event- and composite concentrations. In the Mio-Pliocene Salton Trough (Gulf of California rift basin), for example, oyster bioherms and shell-ridges cap upward-shallowing delta-front cycles, and coral-bearing bioclastites occur along the distal toes of coastal alluvial fans and are banked against inter-fan rocky shorelines. Hiatal concentrations are poorly developed, even along downlap surfaces, and laterally extensive lags are rare.III. Basins of low subsidence (total ≤ few cm/ka maintained over 1–10 ma) are characterized by stratigraphically telescoped sequences with poorly developed (and locally deepening-up) “parasequences”; transgressive surfaces largely coincide with sequence boundaries. Hiatal and lag concentrations are relatively common and close-spaced stratigraphically; these may be taxonomically diverse even in temperate latitudes owing to environmental condensation, and in all instances are taphonomically complex. In the Miocene Chesapeake Group (outcropping U.S. Altantic passive margin), 4 transgressive hiatal shell concentrations lie within 40 m of section; each contains up to ~100 species and rests directly on a 3rd-order sequence boundary. A starved hiatal bone bed with high microplankton diversity marks the major 2nd-order downlap surface; lags of comminuted bones, teeth, and mollusk steinkerns mantle shallow-water unconformities near lap-out.
4
Mury, Antoine, Matthieu Jeanson, Antoine Collin, Dorothée James, and Samuel Etienne. "High Resolution Shoreline and Shelly Ridge Monitoring over Stormy Winter Events: A Case Study in the Megatidal Bay of Mont-Saint-Michel (France)." Journal of Marine Science and Engineering 7, no. 4 (April 4, 2019): 97. http://dx.doi.org/10.3390/jmse7040097.
Full textAbstract:
In the current context of decadal global changes and predicted sea level rise, annual erosion is one of the most obvious indicators of threats to coastal systems. Shoreline monitoring during high energy events is therefore a crucial action to prevent and alleviate future coastal risks. However, most studies look at this on a regional issue basis with limited resolution, and with limited support from field observations. This study addresses this lack by focusing on high resolution (HR) shoreline surveys, combined with wave measurements, in the megatidal Bay of Mont-Saint-Michel. The salt marsh vegetation line and the inner margin of shelly ridges were selected as markers of the stabilized shoreline, to follow its evolution during two high energy winter events, from February 18 to 24, 2015 and from March 19 to 24, 2015, in two different study sites. A transdisciplinary methodology was adopted which included: 1) in situ wave measurements with pressure sensors, 2) topographical data acquisition using a differential GPS, and 3) in silico observations of the shoreline movements through HR aerial and satellite imageries. Our findings highlighted the positive linkage between significant wave height and erosion rate (ranging from 0 to 60.9 m), as well as the variability of coastline responses depending on the geomorphic features.
5
Bérard, Hélène, Edwin Bourget, and Marcel Fréchette. "Mollusk Shell Growth: External Microgrowth Ridge Formation is Uncoupled to Environmental Factors in Mytilus edulis." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 6 (June 1, 1992): 1163–70. http://dx.doi.org/10.1139/f92-130.
Full textAbstract:
Low-frequency (e.g. annual) external ridges have been used in the study of bivalve population dynamics, and it has been suggested that ridges produced at high frequencies are related to environmental factors. Using laboratory and field experiments, we examined the usefulness of fine external growth ridges as markers of cyclic growth patterns in the blue mussel, Mytilus edulis. Shells of M. edulis were analyzed to examine coherence of patterns of ridges on the shells. Analysis was carried out in two steps: (1) An objective method was developed to characterize the ridges by their height and thickness (precision 0.5 μm) and (2) laboratory and field experiments were carried out to determine the influence of environmental factors (immersion and emersion, algal concentration) and biological factors (valve closure) on the periodicity of growth ridge formation. All mussels exhibited unique growth ridge patterns. There was no concordance between growth ridge patterns of individual mussels grown together in the laboratory or in the field. These results refute the hypothesis of a similar growth ridge pattern between individuals in Mytilus at small scales. No relation was found between the mechanical closure of the valves and the formation of growth ridges.
6
Zhang, Jinbo, Qingzhu Zhang, yiyuan Ge, and yongcheng jiang. "Analysis of the Wear-Resistance Characteristics of Bionic Ridge Structures." Applied Engineering in Agriculture 36, no. 5 (2020): 697–702. http://dx.doi.org/10.13031/aea.13680.
Full textAbstract:
HighlightsBionic technology can be applied to resolve agricultural engineering problems.Pangolin Squama and Chlamys Farreri shells possess excellent wear-resistance.Bionic ridges can improve sample wear-resistance.Abstract. Consistent soil contact rapidly wears the soil-engaging components of agricultural machinery, such as ploughs and subsoilers. A bionic method was applied to their structural design to improve component wear resistance. Some animal organs possess excellent wear-resistant structures which can provide design inspiration for improving the wear-resistance of agricultural mechanical parts. Previous research found that many ridges exist on Pangolin squama and Chlamys Farreri shell surfaces. Those ridges cause Pangolin squama and Chlamys Farreri shells to exhibit excellent wear-resistance. Therefore, these ridge structures were applied to the design of experimental subsoiler samples (bionic samples) to enhance their wear-resistance. An abrasive wear tester was utilized to conduct abrasive wear experiments under special experimental conditions. These experimental conditions involved sliding speed, soil particle size, moisture content, and space between the ridges. Finally, nine experiments were conducted that subjected the bionic and flat surface samples to different experimental conditions, and their respective mass-loss quantities were measured. Results show that bionic sample mass loss was less than that of the flat surface samples under the same experimental conditions; bionic sample wear-resistance improved by 77%, 73.8%, 66.9%, 45.4%, 58.9%, 65.5%, 33.1%, 66.4%, and 42.6% when compared with flat surface samples under the same experimental conditions. Orthogonal test results reveal that the soil particle size most significantly affected sample wear-resistance, followed by the space between bionic ridges and the sliding speed. One reason that bionic samples exhibited excellent wear-resistance is that the soil particles underwent a “guiding effect” and a “rolling effect” over the bionic ridge surface, thereby reducing the “micro-plowing” that soil particles generated when moving over the contact surface. Mutual interference among soil particles also reduced wear. Part of the soil particles rushing over the bionic sample surface rebounded back; the rebounded soil particles collided with incoming soil particles, then the speed and kinetic energy of all of the particles decreased and sample surface abrasion declined. Moreover, “vortexes” generated by sample surface air and ridges lead to an “air cushion” effect which can lessen the number of sample surface soil particles, and bionic ridge sample abrasions can be significantly reduced. Abrasion experiment results analysis indicates that bionic ridges distributed on subsoiler sample surfaces can significantly improve wear-resistance. The bionic design method provides a new approach for increasing the wear-resistance of the soil-engaging components of agricultural machinery. Keywords: Abrasive wear, Bionic ridge, Optimal design, Wear-resistance.
7
Parsons, G. Jay, Shawn M. C. Robinson, John C. Roff, and Michael J. Dadswell. "Daily Growth Rates as Indicated by Valve Ridges in Postlarval Giant Scallop (Placopecten magellanicus) (Bivalvia: Pectinidae)." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 3 (March 1, 1993): 456–64. http://dx.doi.org/10.1139/f93-053.
Full textAbstract:
Postlarval giant scallop (Placopecten magellanicus) were examined for daily growth ridges and growth rates by marking the dissoconch shell with Alizarin red dye. The surface of the left valve of postlarvae was composed of concentric ridges, each consisting of a series of irregularly shaped raised nodules. Ridges were clear and distinct in newly settled scallop between ≈0.25 and 2.0 mm shell height. The shell of postlarvae >2 mm was pigmented and ribbed and ridges were no longer distinguishable. Estimated age was significantly correlated with actual age, suggesting that growth ridges were produced daily, under the environmental conditions of Passamaquoddy Bay. Mean growth rate ranged from 32 to 57 μm∙d−1 and was proportional to size and age, but growth of individual scallop showed no coherence in their daily growth patterns. The short-term growth ridges in postlarval giant scallop can be used to determine age and can be applied to comparative growth, mortality, and recruitment studies of newly settled individuals <2.0 mm (≈40 d old postsettlement). The high accuracy and precision of age determination for postlarval scallop differs from studies of short-term internal growth increments of bivalve shells and larval fish otoliths.
8
Patterson, R. Timothy, Charlotte A. Brunner, Rosemary Capo, and Jeremy Dahl. "A paleoenvironmental study of early to middle Pleistocene foraminifera of the Santa Barbara Formation at Santa Barbara, California." Journal of Paleontology 64, no. 1 (January 1990): 1–25. http://dx.doi.org/10.1017/s0022336000042190.
Full textAbstract:
An interval of the Early to Middle Pleistocene history of the California Borderland was assessed using multivariate analysis of foraminifera from the Santa Barbara Formation at Bathhouse Beach, Santa Barbara, California. A census of 93 species of benthic foraminifera and nine species of planktonic foraminifera was compiled from 11 samples from the shelly marls, silts, and sands of the lower member. Most species of benthic foraminifera are rare and only 38 species comprise one percent or more of the population in one or more samples.Paleoenvironment of the sea floor was determined based on benthic foraminifera. R-mode cluster analysis defined five associations which are similar to those of the present-day banks and terraces of the California Borderland. Q-mode cluster analysis grouped samples into four biofacies which characterize shallow banks near 50 meters water depth and off-shore ridges and deep banks averaging 150 meters water depth. The stratigraphic succession of biofacies indicates two transgressive cycles separated by an apparent disconformity between 7.5 and 8.9 meters above the base of the section (between samples 3 and 4).Paleoceanography of surficial waters was interpreted from planktonic foraminifera. Paleotemperature was assessed from the proportion of sinistral to dextral morphs and from the proportion of encrusted, compact morphs to reticulate, globular morphs of Neogloboquadrina pachyderma. The coiling morphs show a warm interval from the base of the section to about 12 meters (between samples 5 and 6), and a cooler interval from about 12 meters to about 24 meters (between samples 10 and 11), and an interval of intermediate paleotemperature in the topmost sample of the section. Changes in the planktonic assemblage do not coincide with the transgressive cycles inferred from the benthic biofacies.The Bathhouse Beach section can be placed chronostratigraphically based on planktonic foraminiferal coiling shifts and strontium isotopic data. The isotopic age range of 400 to 900 Kyr brackets the 600 Kyr age assigned by Lagoe and Thompson (1988) to the Neogloboquadrina pachyderma coiling dominance interval CD9/CD8 boundary which occurs midway in the section, between samples 5 and 6.
9
Richa, Ramy, Essam Osman, Nahed Attia, Hani Arakji, and Mohamed Shokry. "Evaluation of Modified Shell Technique in 3D Ridge Reconstruction: A Clinical and Radiographic Study." European Journal of Dental and Oral Health 4, no. 6 (December 8, 2023): 21–26. http://dx.doi.org/10.24018/ejdent.2023.4.6.307.
Full textAbstract:
Introduction: As a result of tooth loss, alveolar ridge resorption sacrifices bone volume including bone width. In order to replace the lost dentition with implants functionally and esthetically, bone augmentation procedures are carried out. Materials and Methods: Fifteen patients were selected to treat mandibular alveolar ridge resorption with an autogenous block graft harvested using piezoelectric surgical tips and split into two shells using a diamond disk then fixated on the decorticated defective ridge. Particulate xenograft bovine bone was then inserted between the fixated shell and ridge, the second shell was used to roof the bone particles. Results: The modified shell technique could be an alternative to other ridge augmentation techniques. This study shows promising clinical and radiographic results that carry the advantages of being: safe and precise cutting using Piezoelectric tips, the statistical data showed a significant difference in 3D bone volume where no unfavorable complication was detected. Conclusion: The modified shell technique showed a reliable technique in cases of 3D ridge reconstruction since it holds the advantages of autogenous bone properties and the rigidity of the bone shells that maintain the space necessary for augmentation. The use of PRF can accelerate wound healing and minimize the risk of flap dehiscence as well as it can speed up bone formation.
10
azab, mostafa, mohamed diaa, amr ghanem, and mahmoud badr. "Three-Dimensional Maxillary Alveolar Ridge Augmentation Using Three-Dimensional Maxillary Alveolar Ridge Augmentation Using Modified Cortical Shell Technique and Composite Bone Graft." future dental journal 7, no. 1 (June 1, 2021): 7–14. http://dx.doi.org/10.54623/fdj.7012.
Full textAbstract:
Objective: The present study was performed to assess the 3D alveolar ridge augmentation using the cortical shell from retromolar region and composite bone particulate regarding the width of the residual alveolar ridge. Methods: Thirteen patients with age range 21-40 years old having atrophic anterior maxillary ridge ≤3mm horizontally were included in the study. All patients were subjected to ridge augmentation using composite bone graft and retromolar cortical shell that was fixed in place by two micro-screws. The alveolar ridges were assessed and compared by cone beam computed tomography (CBCT) in the pre-operative, immediate and 4 months post-operative phases by taking linear measurements at the same points after making fusion. The measurements were taken at the crest of the ridge, midway and more apically. The CBCT images were evaluated for the actual gain in width of the alveolar ridge. Statistical analysis was performed to compare CBCT and clinical findings. Results: At the crest of the ridge, midway and more apically the results showed a statistically significant difference between pre-operative and immediate post-operative results (P0.05). The mean increases in crestal bone width, midway and apically at 4 months postoperatively were 3.66mm, 4.01mm and 3.5mm respectively. Conclusion: 3D reconstruction of anterior maxillae with autogenous retromolar cortical shell is a reliable technique with stable outcomes. Two micro- screws Stabilization provides stability and minimal graft resorption. Moreover, the technique allows for implant placement 4 months post-operatively without further re-grafting.
11
Rodrigues, Kathleen, Frank W. Stapor, William J. Rink, James S. Dunbar, and Glen Doran. "A 5700-year-old beach-ridge set at Cape Canaveral, Florida, and its implication for Holocene sea-level history in the southeastern USA." Holocene 32, no. 1-2 (October 10, 2021): 40–56. http://dx.doi.org/10.1177/09596836211049975.
Full textAbstract:
The Cape Canaveral Peninsula is the largest Holocene coastal sand deposit composed of beach ridges on the Atlantic coast of Florida. It is composed of 16 beach-ridge sets that are separated by erosional surfaces. Despite its prominence as a Holocene coastal depocenter, there are a limited amount of chronological data constraining the timing of its formation. In this study, we apply optically stimulated luminescence (OSL) dating on sand-sized quartz and radiocarbon dating on individual marine shells to develop a refined chronology of the Cape Canaveral beach-ridge plain with particular focus on constraining the depositional age of the northwesterly-most, and geographically oldest, beach-ridge set on the peninsula. We obtain an average OSL age of 5680 ± 240 years ( n = 4) for the initiation of coastal deposition at Cape Canaveral. The new ages, and the organization of beach ridges into 16 distinct sets indicates that the Cape Canaveral beach-ridge plain experienced an ~5700-year history of alternating deposition and erosion, with 75% of present-day Cape Canaveral (Beach-ridge Sets 5–16) deposited over the past 2000 years and Beach-ridge Sets 8–16 comprising 50% of the area over the past 1000 years. Because the minimum swale elevations of the ~5700-year Beach-ridge Set 1, and those of all the younger beach-ridge sets, are within several decimeters of present-day mean higher high water, we hypothesize that all the beach ridges present at Cape Canaveral could have been deposited at or within decimeters of present-day sea level. There is no evidence for Holocene “highstand” events over the past 5700 years in the published sea level curves from northeast and south Florida, which are based on subsurface estuarine foraminifera/leaf litter and mangrove peat data, respectively. This dichotomy illustrates the need to integrate both subaerial and subsurface data to produce a more realistic Holocene sea-level curve for the southeastern United States.
12
Kamadjaja, Michael JK, Bambang AS Tumali, Harry Laksono, Nike Hendrijantini, Melinda L. Ariani, Natasia, and Tata P. Mawantari. "Effect of Socket Preservation Using Crab Shell-Based Hydroxyapatite in Wistar Rats." Recent Advances in Biology and Medicine 6 (2020): 1. http://dx.doi.org/10.18639/rabm.2020.1116232.
Full textAbstract:
Tooth extraction can cause 1.5-2 mm (vertical) and 40-50% (horizontal) alveolar bone resorption to occur for 6 months after extraction and will continue if it is not treated. Alveolar bone resorption will affect the retention, stability, and comfort in the use of dentures because adequate alveolar bone volume and structure of alveolar ridge are very important to obtain optimal function and prosthetic reconstruction. Currently, there are techniques and materials that can be used to minimize bone resorption. Preservation of alveolar ridges with crab shell-based hydroxyapatite can minimize bone resorption because it has good biocompatibility, osteoconduction, and osteoinduction. The aim of this study is to prove the effectiveness of hydroxyapatite from crab shells in increasing the area of bone trabeculae, transforming growth factor-beta 1(TGF-β1), and alkaline phosphatase (ALP). This laboratory research is an experimental laboratory work with a post-test group design. Crab shell-based hydroxyapatite gel (Portunus pelagicus) was given after the post-tooth socket extraction of the left lower central incisor of Wistar rats, observing the area of trabeculae, TGF-β1, and ALP on the 14th day and 28th day. Hydroxyapatite is made from the calcination process of crab shells using a furnace at 1000°C for 2 h followed by sifting to powder. The powder is added with carrageenan and distilled water so that it becomes a gel preparation. The results of this study were analyzed using the One-way ANOVA test with IBM SPSS version 20. The area of trabeculae, TGF-β1, and ALP between the control group and the treatment group showed p<0.05, which means there were significant differences between the groups. The study showed that hydroxyapatite from the crab shell (P. pelagicus) can increase the area of trabeculae, TGF-β1, and ALP in the post-extraction socket of Wistar rat’s teeth.
13
Kohn, Alan J. "Slip-resistant silver-feet: shell form and mode of life in lower Pleistocene Argyropeza from Fiji." Journal of Paleontology 60, no. 5 (September 1986): 1066–74. http://dx.doi.org/10.1017/s0022336000022599.
Full textAbstract:
Asymmetric sculpture in the form of tubercles or ridges on the shells of large (mean shell length ~60 mm) turritelliform gastropods has previously been shown to enhance efficiency of the shell as a penetration anchor in burrowing through coarse sediment. The small (<8 mm) turritelliform shells of all species of Argyropeza (Family Cerithiidae) have both of these ratchetlike sculptural features. Four lines of evidence from Lower Pleistocene A. divina and A. schepmaniana from Fiji support the interpretation that they help resist back-slippage: cross-orientation, frictional asymmetry, allometric shallowing, and allometric densing of sculptural elements. In addition, excellent state of preservation including protoconch sculpture, near coplanarity of aperture and ventral side of shell, and susceptibility to drilling predation by naticids support the conclusion that these gastropods burrowed in the sediment that formed the siltstone in which they are now preserved. A direct relationship is proposed between height of ratchet sculpture on turritelliform gastropod shells of approximate length range 5–100 mm and the grain size of sediments they inhabit ranging from silts to coarse sands.
14
CZAJA, ALEXANDER, ALAN P. COVICH, THOMAS A. NEUBAUER, JOSÉ LUIS ESTRADA-RODRÍGUEZ, VERÓNICA ÁVILA-RODRÍGUEZ, and JORGE SÁENZ MATA. "A new freshwater snail genus and species (Gastropoda: Caenogastropoda, Cochliopidae) with extremely spinous shells from sub-recent spring deposits in northeastern Mexico." Zootaxa 5169, no. 5 (August 2, 2022): 472–80. http://dx.doi.org/10.11646/zootaxa.5169.5.5.
Full textAbstract:
A new monotypic genus of freshwater snail from late Holocene spring deposits in Viesca, Coahuila (Mexico), is described based on shell morphology. Spinopyrgus luismaedai n. gen. et n. sp. has two to three carinate shells with long and wide shovel-shaped spines, strong axial ridges and a pointed protoconch. All sculptural ornamentations on the teleoconch are part of the calcareous shell material and not projections of the periostracum. This combination of shell features and their almost “marine-like” appearance is unknown among North American recent and fossil freshwater snails. Because of its shell characteristics, we placed the new genus tentatively in the Cochliopidae. The springs of Viesca dried up in the second half of the 20th century so that any living occurrence of this species in neighboring areas is unlikely, rendering the new genus and species possibly extinct.
15
Kulygin, Valerii, and Samir Misirov. "Beach ridges detection on the Dolgaya Spit based on remote sensing data." InterCarto. InterGIS 27, no. 1 (2021): 330–38. http://dx.doi.org/10.35595/2414-9179-2021-1-27-330-338.
Full textAbstract:
The study of the ridge systems’ morphology on accumulative coastal land forms makes it possible to reconstruct their development. The spatial orientation and height of the beach ridges provide information on the predominance of certain processes at different time intervals. The Dolgaya Spit, which is one of the largest accumulative forms of the Sea of Azov, is characterized by the presence of well-distinguishable generation of sand-shell ridges. The article discusses the possibility of using various remote sensing data to identify beach ridges on the Dolgaya Spit. In this study the data of ground measurements of elevation points performed during the expedition in the summer of 2020 are used. The statistical characteristics of the ridges on the investigated area of the spit are given. The analysis of the possibility of identifying beach ridges on the spit based on high-resolution satellite optical images has been done. It was concluded that it is impossible to unambiguously determine the ridges, since the optical characteristics of the soil and vegetation cover on the Dolgaya Spit do not allow separation of the microrelief forms. The second source of remote sensing data was aerial photography of a part of the Dolgaya Spit using the unmanned aerial vehicle “Phantom 3 PRO”, followed by photogrammetric processing of the obtained digital images. The stages of processing the survey results for the construction of a digital elevation model and an orthomosaic of the investigated area are considered. The quality of the obtained digital elevation model was assessed by comparison with ground measurements of elevation points. The article discusses the source of errors in the obtained digital elevation model. It is noted that the construction of a digital elevation model with acceptable quality is possible only for the spit’s regions with sparse vegetation cover.
16
VAN SOEST, ROB W. M. "Sponges of the Guyana Shelf." Zootaxa 4217, no. 1 (January 12, 2017): 1. http://dx.doi.org/10.11646/zootaxa.4217.1.1.
Full textAbstract:
Sponges collected on the Guyana Shelf, predominantly in Suriname offshore waters, by Dutch HMS ‘Snellius’ O.C.P.S. 1966, HMS ’Luymes’ O.C.P.S. II 1969, and HMS ‘Luymes’ Guyana Shelf 1970 expeditions are described in this study. Sponges were obtained by trawling, dredging or grabbing on sandy, muddy, shelly, and fossil reef bottoms at 88 stations between 19 and 681 m depth. A total of 351 samples were identified to species level, each consisting of one or more specimens of a given species from each individual station (together comprising 547 individuals and fragments). The collection yielded 119 species together belonging to all sponge classes, but in large majority are Demospongiae. All species are identified to species level, occasionally tentatively, and all are described and illustrated. A new subgenus is proposed, Tedania (Stylotedania) subgen. nov. and a previously synonymized genus, Tylosigma Topsent, 1894 is revived. Thirtysix species were found to be new to science, excluding the first Central West Atlantic record of the genus Halicnemia, not named at the species level because of lack of sufficient material. The new species erected are, in alphabetical order: Amphoriscus ancora sp. nov., Biemna rhabdotylostylota sp. nov., Callyspongia (Callyspongia) scutica sp. nov., Chelonaplysilla americana sp. nov., Cladocroce guyanensis sp. nov., Clathria (Axosuberites) riosae sp. nov., Clathria (Clathria) gomezae sp. nov., Clathria (Microciona) snelliusae sp. nov., Clathria (Thalysias) complanata sp. nov., Clathria (Thalysias) zeai sp. nov., Coelosphaera (Coelosphaera) lissodendoryxoides sp. nov., Craniella crustocorticata sp. nov., Diplastrella spirastrelloides sp. nov., Epipolasis tubulata sp. nov., Erylus rhabdocoronatus sp. nov., Erylus surinamensis sp. nov., Geodia pocillum sp. nov., Geodia sulcata sp. nov., Hemiasterella camelus sp. nov., Hymedesmia (Stylopus) alcoladoi sp. nov., Hymenancora cristoboi sp. nov., Penares sineastra sp. nov., Hymerhabdia kobluki sp. nov., Leucosolenia salpinx sp. nov., Petrosia (Strongylophora) devoogdae sp. nov., Placospongia ruetzleri sp. nov., Pyloderma tropicale sp. nov., Raspailia (Parasyringella) thamnopilosa sp. nov., Raspailia (Raspailia) johnhooperi sp. nov., Sphaerotylus bouryesnaultae sp. nov., Spirastrella erylicola sp. nov., Stelletta vervoorti sp. nov., Suberites crispolobatus sp. nov., Tedania (Stylotedania) folium subgen. nov. sp. nov., Timea tylasterina sp. nov., and Tylosigma ostreicola sp. nov. Two new combinations are proposed: Amphimedon nanaspiculata (Hartman, 1955) comb. nov. and Oceanapia ascidia (Schmidt, 1870) comb. nov. In addition, for two preoccupied combinations, new names, Coelosphaera (Coelosphaera) barbadensis nom. nov. and Hymedesmia (Hymedesmia) rowi nom. nov., are erected. The spatial distribution of the collected specimens over the Guyana Shelf was traced and the results were compared with existing information on bottom conditions. There was a convincing correlation between the location of fossil reefs and other hard substrates such as shell ridges with peaks in the occurrence of species diversity and specimen numbers. Stations made on sand and mud bottoms away from these zones of hard substrates were generally poor in species, but some were found to be rich in individuals of specialized soft bottom dwellers such as Tetilla pentatriaena, Tribrachium schmidtii, Fangophilina submersa, and Oceanapia species. The species composition of the Guyana Shelf was compared with that of neighbouring regions of the Caribbean and from North and East Brazil (Díaz in Miloslavich et al. 2010; Muricy et al. 2011). About 35% of the species encountered are widespread in the Central West Atlantic, occurring both to the north and to the south. Indications that the Guyana Shelf sponge fauna is clearly transitional are southernmost occurrences for Caribbean species (about 30%), and northernmost occurrences of Brazilian species (13%), with a high proportion (25%) of new species, which may be expected to have distributions extending to the Caribbean, to Brazil or both regions.
17
Thomas, M., and RW Day. "Site selection by a small drilling predator: Why does the gastropod Haustrum baileyanum drill over muscle tissue of the abalone Haliotis rubra?" Marine and Freshwater Research 46, no. 3 (1995): 647. http://dx.doi.org/10.1071/mf9950647.
Full textAbstract:
The muricid gastropod Haustrum baileyanum bores holes through the shell of the abalone Haliotis rubra to feed on the underlying tissue. Analysis of the borehole positions on shells of H. rubra showed that they were significantly concentrated in the area where the abalone muscle is attached. This is in sharp contrast to other drilling predators of molluscs. The whelks did not change their choice of drilling site in response to experimental removal of the shell surface, or to changes in shell thickness. They may use shell ridges and possibly the morphology of the abalone shell to determine where to drill. The behaviour of the prey appears unlikely to affect the drilling position, and shell repair by the abalone is too slow to act as an effective defence in any area. The area over the muscle is the thickest part of the shell covering abalone tissue, and requires a much longer time to penetrate, as drilling is slow. The cost of drilling through the thicker part of the shell is presumably outweighed by the benefits gained from feeding on the muscle tissue. The muscle tissue has a higher energy content than the visceral tissue found elsewhere, especially when measured per unit volume.
18
Lezin, Peter, and Lyudmila Flyachinskaya. "Shell sculpture formation in bivalves of the genus Hiatella under different temperature conditions." Journal of the Marine Biological Association of the United Kingdom 95, no. 8 (March 13, 2015): 1621–27. http://dx.doi.org/10.1017/s0025315415000259.
Full textAbstract:
This study examines the effect of water temperature on the formation of shell sculpture in young molluscs of the genus Hiatella. The larvae of H. arctica and H. gallicana were maintained under laboratory conditions at different temperature regimes. The animals were reared from late veligers to juveniles with a shell length of 700 μm. The results of the experiment showed that the shell sculpture, which is a diagnostic species character, was developed to various degrees at different temperatures. The larvae of each species grew to juveniles with variously pronounced shell sculptures ranging from a complete absence of sculpturing to its maximum development. The individuals with smooth shells like those of H. gallicana were the most abundant among the molluscs reared at +5°С. At +12°С, all molluscs formed ridges and two rows of long spines in the posterior portion of the shell, which is typical for H. arctica. At +8°С, the molluscs developed various intermediate forms of shell sculpture. It was, therefore, demonstrated that the development and prominence of shell sculpture is determined by environmental temperature. These results are discussed with regards to the validity of using shell sculpture as a taxonomic character for species in the genus Hiatella.
19
Katkova, V. I., T. M. Beznosova, and V. N. Filippov. "Pseudo-morphogenesis in the shells of the Silurian brachiopods." Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences 3 (2021): 49–55. http://dx.doi.org/10.19110/1994-5655-2021-3-49-55.
Full textAbstract:
The analysis of paleontological data, the study of mineral matter transformation involving live organisms in various rocks is important for the understanding of the events of the geological past. The aim of this work is to identify the bio-genic factor in the process of pseudo-morphogenesis in the shell sashes of the Early Silurian brachiopods from the car-bonate rocks of the Chernyshev Ridge. Structural and microscopic methods (Shimadzu XRD 6000; Fourier spectrometer InfraLum FT-02; JSM 6400 JEOL; VEGA3 TESCAN; MIN-8) were used to study quartz pseudomorphoses in the sashes of four shells of the Early Silurian brachiopods Borealis sр. of Pentamerida order from the carbonate strata of the Chernyshev Ridge. The salicification of the brachiopod shell walls resulted in the complete replacement of the original carbonate skeleton with a change in its structural organization. It is established that quartz is the main mineral component of the intra-shell material and secondary dolomite crystals and newly formed calcite aggregates. The paper discusses the participation of Early Paleozoic and modern cyanobacterial symbionts in the replacement of primary calcite with quartz and the formation of quartz crystalline aggregates on the shell walls. It is shown that quartz on the surface of shell sashes and in the intra-shell substance of brachiopods has undergone repeated transformations due to the combination of ancient and modern weathering processes.
20
Thieltges, David W., Ian Saldanha, Tommy L. F. Leung, and Robert Poulin. "Contribution of parasites to intra- and inter-site variation in shell morphology of a marine gastropod." Journal of the Marine Biological Association of the United Kingdom 89, no. 3 (July 29, 2008): 563–68. http://dx.doi.org/10.1017/s0025315408002294.
Full textAbstract:
In gastropods, variation in shell morphology can be caused by the action of several biotic and abiotic factors. While much of this variation is seen in comparisons between different sites or populations, there is also substantial variation in shell morphology among individuals living side by side. We investigate the effect of trematode parasitism on both intra- as well as inter-site variation in the morphology of the New Zealand whelk Cominella glandiformis. We found that both infection by the trematode Curtuteria australis and site of origin had significant effects on several morphometric dimensions of the snail shell, with some interactions between the two factors. On its own, infection by C. australis accounted for 20 to 60% of the variance in shell morphology, depending on the dimension measured. Infected snails also had smoother shells, with less prominent ridges, than their uninfected conspecifics. Other trematode species, infecting whelks at much lower prevalence, also had impacts on shell morphology, but not necessarily in the same direction as C. australis. Overall, parasitism may be an important factor in explaining intra- and inter-site variation in snail phenotype, with potential repercussions for snail populations and their interactions with other community members.
21
SPAGNUOLO, JORGE, ESTER FARINATI, and SALVADOR ALIOTTA. "Análisis tafonómico de moluscos holocenos en el área costera del Estuario de Bahía Blanca, Argentina." Pesquisas em Geociências 28, no. 1 (June 30, 2001): 3. http://dx.doi.org/10.22456/1807-9806.20163.
Full textAbstract:
At the south west of the Buenos Aires province, Argentina, on the northern coast of the Bahía Blanca Estuary, sand-shell ridges sub-parallel to the coastline generated during the Holocene transgression-regression were deposited. These structures are composed mostly of coarse to medium sand and a high proportion of molluscs shells (19 species of bivalves and 16 species of gastropods). For this study three taxa from the fossil association located in the ridges (Brachidontes rodriguezi, Tegula patagonica and Crepidula aculeata) were selected and the mechanisms of taphonomic alteration that affected them were qualified. By means of ternary taphograms the variation of five taphonomic attributes (bioerosion, encrustation. fragmentation. wear and dissolution) was established. It has been determined that the bioestratinomic processes are subordinated to the fossildiagenetic mechanisms, where dissolution has left a series of taphonomic signatures. Based upon the taphonomic attributes of the fossil association a high stand sea level cycle with an important contribution of storm waves that affected the biogenic production area were established as a representation of the paleoenvironmental evolution.
22
Rez, Peter. "Electron Ionization Cross Sections for Atomic Subshells." Microscopy and Microanalysis 9, no. 1 (January 31, 2003): 42–53. http://dx.doi.org/10.1017/s1431927603030083.
Full textAbstract:
Ionization of atoms is the first step in many analytical procedures. The cross section for ionizing a particular atomic shell is essential for calculating the magnitude of analytical signals. Calculations using atomic wave functions for various shells of all elements relevant for X-ray microanalysis over a range of electron energies up to 400 keV were performed. The calculations for high energies above threshold can be considerably simplified by using the mathematical form of the Bethe ridge that dominates the scattering in this region. Corrections for exchange at low energies above threshold are incorporated in these calculations. A selection of results showing the effects of different approximations on ionization cross sections for K, L, and M shells is presented.
23
Dewing, Keith. "Hinge modifications and musculature of strophomenoid brachiopods: examples across the Ordovician-Silurian boundary, Anticosti Island, Quebec." Canadian Journal of Earth Sciences 38, no. 2 (February 1, 2001): 125–41. http://dx.doi.org/10.1139/e00-027.
Full textAbstract:
Six modifications to the hinge occur in strophomenoid brachiopods from Anticosti Island: (1) overhanging socket ridges; (2) posterolateral socket ridges along the interarea articulate with grooves on the posterior of teeth; (3) anteromedian dental notches articulate with the crests of socket ridges; (4) dental crenulations on the surfaces of teeth mesh with socket ridges; (5) denticles extend laterally to the cardinal extremities; and (6) the margin of the ventral interarea fits into a long socket along the dorsal interarea forming a lateral tooth. Denticulate hinges and dental notches that typify Silurian and Devonian strophomenids begin in the fauna of the Ellis Bay Formation. Thus the most important interval of strophomenid faunal turnover was at the base of the Gamachian (the base of the Hirnantian) and not at the OrdovicianSilurian boundary. Muscle attachment pads in the delthyrial cavity do not correspond to the positions of either the adductor or diductor muscle scars. Pedicle adjustor muscles in modern brachiopods occupy this position. The round gap between the median fold of the pseudodeltidium and groove on chilidium is proposed as the point of emergence of the pedicle muscle. The tiny foramen, commonly sealed early in growth, is suggested to be part of a neanic water-intake system, active before the growth of the cardinal process in ephebic shells. Once the cardinal process appeared, the foramen was blocked. Recurring types of strophomenid ornamentation, such as posteriorly steepened rugae and checkerboard ornamentation, may have served as a plow to redistribute sediment as the shell was pulled backwards along the pedicle.
24
Barbour, Terry E., Kenneth E. Sassaman, Angelica Maria Almeyda Zambrano, Eben North Broadbent, Ben Wilkinson, and Richard Kanaski. "Rare pre-Columbian settlement on the Florida Gulf Coast revealed through high-resolution drone LiDAR." Proceedings of the National Academy of Sciences 116, no. 47 (November 4, 2019): 23493–98. http://dx.doi.org/10.1073/pnas.1911285116.
Full textAbstract:
Drone-mounted, high-resolution light detection and ranging reveals the architectural details of an ancient settlement on the Gulf Coast of Florida without parallel in the Southeastern United States. The Raleigh Island shell-ring complex (8LV293) of ca. 900 to 1200 CE consists of at least 37 residential spaces enclosed by ridges of oyster shell up to 4 m tall. Test excavations in 10 of these residential spaces yielded abundant evidence for the production of beads from the shells of marine gastropods. Beads and other objects made from gulf coastal shell were integral to the political economies of second-millennium CE chiefdoms across eastern North America. At places as distant from the coast as the lower Midwest, marine gastropods were imported in raw form and converted into beads and other objects by craftspeople at the behest of chiefs. Bead making at Raleigh Island is exceptional not only for its level of production at the supply end of regional demand but also for being outside the purview of chiefly control. Here we introduce the newly discovered above-ground architecture of Raleigh Island and outline its analytical value for investigating the organization of shell bead production in the context of ancient political economies. The details of shell-ring architecture achieved with drone-mounted LiDAR make it possible to compare the bead making of persons distributed across residential spaces with unprecedented resolution.
25
Hwang, Chung-Chi, and Shu-Ping Wu. "Two new species of Satsuma A. Adams, 1868 from Taiwan (Pulmonata, Camaenidae)." ZooKeys 795 (November 8, 2018): 115–26. http://dx.doi.org/10.3897/zookeys.795.28958.
Full textAbstract:
Two new sinistral species of the genusSatsumaA. Adams, 1868,Satsumasquamigerasp. n.andSatsumaadiriensissp. n., from southern Taiwan are described.Satsumasquamigerasp. n.is characterized by a microsculpture comprising coarse, irregularly-spaced ridges and dense, easily-dislodged triangular scales on its sinistral shell, an angulated periphery, and partly-opened umbilicus. This species inhabits secondary forests in lowland hills.Satsumaadiriensissp. n.is characterized by a thin, fragile smooth shell with microsculpture of coarse, loose ridges, a rounded periphery, completely-opened umbilicus, and elongated penial verge formed by two main pilasters. This new species was collected in a mountainous, mid-elevation, broad-leafed forest.
26
Lenoble, Arnaud. "Drymaeus virgulatus, an extirpated land snail species on Saint Kitts and Tintamarre islands." Novitates Caribaea, no. 18 (July 15, 2021): 193–206. http://dx.doi.org/10.33800/nc.vi18.270.
Full textAbstract:
The land snail species Drymaeus virgulatus (Férussac, 1821) is recorded in St. Kitts in the form of 21 complete or fragmented shells collected on the island in November 2019. The complete shells were collected on the backshores of South Frigate Bay and Majors Bay, while shell fragments come from naturally exposed sections of the North Frigate Bay sand ridge, where they date to the pre-Columbian period. This evidence therefore attests to the past presence of this species on the island. The absence of this taxon from recent malacological surveys points to it having been extirpated from St. Kitts. Apertural fragments of a large bulimulidae collected in the caves of Tintamarre Island, near St. Martin, are also related to this taxon, adding a second West Indian island from which this species apparently disappeared in recent centuries.
27
Passos, Flávio Dias, and Adolpho Birman. "New records of Bentharca asperula (Dall, 1881) (Mollusca, Bivalvia, Arcidae) from Brazil." Biota Neotropica 9, no. 4 (December 2009): 281–83. http://dx.doi.org/10.1590/s1676-06032009000400032.
Full textAbstract:
Specimens of Bentharca asperula (Dall, 1881) were obtained from deep waters of the coasts of the Rio de Janeiro and São Paulo States, and their shells described, illustrated and compared with descriptions and illustrations obtained from the literature. This species has a small strongly inequilateral shell, trapezoidal in outline and expanded ventro-posteriorly; their umbos are placed at about 1/3 of the anterior length of their straight hinge line. The external sculpture consists of irregular spaced concentric ridges, intercepted by fine radiating striae; the periostracum is hairy, forming a cover as a thatch. Hinge teeth are small, disposed in two series interrupted by the ligament. With this finding of living specimens from the Bacia de Campos, the distribution of B. asperula can now be extended in the Brazilian coast, confirming its wide spread in the Atlantic Ocean.
28
Yue, Zhao, Stefan Bengtson, and Stephen W. F. Grant. "Biology and functional morphology of Cloudina, the earliest known metazoan with a mineralized skeleton." Paleontological Society Special Publications 6 (1992): 325. http://dx.doi.org/10.1017/s2475262200008856.
Full textAbstract:
The earliest known skeletal metazoan, Cloudina, was widespread in the late Neoproterozoic. We report here on phosphatized specimens of Cloudina sp. from dolomites of the Dengying Formation, 30 m below the first Cambrian skeletal fauna, in the Lijiagou section, Shaanxi Province, China. The specimens exhibit new details of shell morphology and fine structure that offer insights concerning the mechanism of shell accretion and the selective pressures influencing skeletogenesis in metazaons.Cloudina formed curved to sinous tubular shells 0.2-8 mm in diameter and up to 4 cm in length. They consist of numerous thin (5-10 μm) calcareous layers, each in the form of a slightly flaring tube. New layers were deposited above and to one side of the previous layer, giving rise to a series of eccentrically nested shell laminae. Some of the phosphatized layers exhibit tight folding or wrinkling that may have been primary (imparting additional strength) or secondary (related to plastic deformation of organic-rich shell material). Pore space existed between terminal thin flanges, but concentric ridges may have served to strengthen the free standing portions of shell layers. SEM and cathodoluminescence of polished thin sections also reveal that each shell layer may itself have been constructed of an organized layering of organic matrix and carbonate, suggesting a fairly sophisticated biologic control over shell formation. The presence of circular holes, the size of which correlates positively with tube diameter, moreover, strongly suggests that one function of the shell was to protect the Cloudina organism from predatorial and/or parasitic attack.The taxonomic status of Cloudina remains problematic. Rare specimens of the Lijiagou Cloudina which show two younger tubes growing within an older single tube suggest that the organism was capable of asexual reproduction by longitudinal fission. Such a latent tendency is not compatible with previously proposed affinities with polychaete worms.
29
Rylaarsdam, Jessica R., Bogdan L. Varban, A. Guy Plint, Lisa G. Buckley, and Richard T. McCrea. "Middle Turonian dinosaur paleoenvironments in the Upper Cretaceous Kaskapau Formation, northeast British Columbia." Canadian Journal of Earth Sciences 43, no. 6 (June 1, 2006): 631–52. http://dx.doi.org/10.1139/e06-014.
Full textAbstract:
The Kaskapau Formation is a mudstone-dominated wedge up to 950 m thick that spans late Cenomanian to middle Turonian time. The formation has a prominent wedge geometry and was deposited in the foredeep of the Western Canada Foreland Basin. In outcrop in northeast British Columbia, nearshore sandstones are locally well developed and include rare wedges of nonmarine strata. On Quality Creek, near Tumbler Ridge, 11 m of nonmarine strata contain abundant dinosaur tracks and the first in situ dinosaur bone reported from British Columbia. This site, at a paleolatitude of about 67°N, preserves a rare glimpse of Turonian terrestrial environments during global eustatic highstand. Three main dinosaur habitats are recognized: strandplain and beach-ridge; freshwater lake; and brackish lagoon. Back-beach sandstone has a relief of about 2.5 m, interpreted as beach ridges; sandy coals containing abundant dinosaur tracks represent inter-ridge slough deposits. Overlying lake deposits comprising laminated muds with freshwater molluscs grade up into rooted muddy siltstone and locally, dinoturbated sandstone. Lake deposits are capped by lagoonal mudstone with abundant brackish-water molluscs, locally including a dinosaur-trampled oyster bioherm. The upper parts of sandy lagoonal deltas are pervasively dinoturbated. Sandstone filling a tidal channel contains logs, oyster shells, and bones of dinosaurs, turtles, and crocodiles, as well as fish scales. The lagoonal succession is erosively overlain by offshore sandy mudstones. Various lines of evidence suggest that the mean annual temperature at this sea-level location was about 14 °C, with a cold-month mean no less than 5.5 °C. The high-latitude location implies a significant period of winter darkness, and correspondingly diminished plant productivity.
30
Pathy, Diane A., and Gerald L. Mackie. "Comparative shell morphology of Dreissena polymorpha, Mytilopsis leucophaeata, and the "quagga" mussel (Bivalvia: Dreissenidae) in North America." Canadian Journal of Zoology 71, no. 5 (May 1, 1993): 1012–23. http://dx.doi.org/10.1139/z93-135.
Full textAbstract:
Dreissena polymorpha, recently introduced to freshwater habitats of North America, has been confused with Mytilopsis leucophaeata, a related species that is native to brackish and fresh waters of North America. The 1991 discovery of a second exotic dreissenid mussel, the "quagga" mussel, suggests there may be more than one species of Dreissena in the Great Lakes, resulting in even more confusion in identification within the family Dreissenidae. To help distinguish the species, internal and external features, ultrastructure, and composition of D. polymorpha, M. leucophaeata, and quagga mussel shells were determined using stereoscopic, scanning electron microscopic, and X-ray diffraction techniques. The most reliable diagnostic feature is the presence of an apophysis in M. leucophaeata and its absence in D. polymorpha and the quagga mussel. Mytilopsis leucophaeata and quagga mussels also lack the acute shoulder or ridge located ventrolaterally. Dreissena polymorpha, M. leucophaeata, and the quagga mussel all have an outer crossed-lamellar shell structure with an inner complex crossed-lamellar shell structure and a thin, prismatic pallial myostracum between. Microtubules are more prominent in M. leucophaeata than in D. polymorpha. No microtubules were found in the quagga mussels. Shells of D. polymorpha, M. leucophaeata, and the quagga mussel are composed entirely of aragonite crystals.
31
B.S. PARMAR, N.I. PATEL, BRIJAL R. PATEL, JAYDIP MAKWANA, and FORAM K. PATEL. "Effective management practices for enhancing castor (Ricinus communis) productivity in dryland agriculture." Indian Journal of Agronomy 67, no. 2 (January 2, 2023): 180–85. http://dx.doi.org/10.59797/ija.v67i2.116.
Full textAbstract:
A field experiment was conducted during rainy (kharif) season of 2016, 2017 and 2018 at Centre for Natural Resources Management, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, to study the effect of land configurations and mulching on productivity and rainwater-use efficiency of castor (Ricinus communis L.). The experiment was laid out in a randomized block design with 4 replications in loamy sand soil, having goodinfiltration capacity. The treatment comprised, viz. control (conventional method), raised-bed method, ridge and furrow method, ditch method, conventional method with castor-shell mulch, conventional method with plastic mulch, raised-bed with castor-shell mulch, raised bed with plastic mulch, ridge and furrow method with castor-shell mulch, ridge and furrow method with plastic mulch, ditch method with castor-shell mulch, ditch method with plastic mulch. The results of pooled data of 3 years showed that, the conventional method with plastic mulch resulted in higher seed yield (1,943 kg/ha), followed by ridge and furrow method with castor-shell mulch and conventional method with castor-shell mulch. However, the higher rainwater-use efficiency (3.57 kg/ha-mm of water) was observed in the treatment of raised bed with plastic mulch. The magnitude of increase in seed yield in conventional method with castor-shell mulch over the control was 56.74% on pooled basis. Thus, use of castor-shell mulch or crop-residue as low-priced input in dryland farming may be encouraged for enhanced in-situ moisture conservation, castor-grain yield and rainwater-use efficiency.
32
Zhang, Jun, Peng Yu, Yang Zhao, Qinyan Zhou, Jiayu Yang, Qingtao Hu, Tiantian Liu, Chuanhe Bao, Shiping Su, and Jian-Fang Gui. "Global Analysis of Transcriptome and Translatome Revealed That Coordinated WNT and FGF Regulate the Carapacial Ridge Development of Chinese Soft-Shell Turtle." International Journal of Molecular Sciences 22, no. 22 (November 18, 2021): 12441. http://dx.doi.org/10.3390/ijms222212441.
Full textAbstract:
The turtle carapace is composed of severely deformed fused dorsal vertebrae, ribs, and bone plates. In particular, the lateral growth in the superficial layer of turtle ribs in the dorsal trunk causes an encapsulation of the scapula and pelvis. The recent study suggested that the carapacial ridge (CR) is a new model of epithelial–mesenchymal transition which is essential for the arrangement of the ribs. Therefore, it is necessary to explore the regulatory mechanism of carapacial ridge development to analyze the formation of the turtle shell. However, the current understanding of the regulatory network underlying turtle carapacial ridge development is poor due to the lack of both systematic gene screening at different carapacial ridge development stages and gene function verification studies. In this study, we obtained genome-wide gene transcription and gene translation profiles using RNA sequencing and ribosome nascent-chain complex mRNA sequencing from carapacial ridge tissues of Chinese soft-shell turtle at different development stages. A correlation analysis of the transcriptome and translatome revealed that there were 129, 670, and 135 codifferentially expressed genes, including homodirection and opposite-direction differentially expressed genes, among three comparison groups, respectively. The pathway enrichment analysis of codifferentially expressed genes from the Kyoto Encyclopedia of Genes and Genomes showed dynamic changes in signaling pathways involved in carapacial ridge development. Especially, the results revealed that the Wnt signaling pathway and MAPK signaling pathway may play important roles in turtle carapacial ridge development. In addition, Wnt and Fgf were expressed during the carapacial ridge development. Furthermore, we discovered that Wnt5a regulated carapacial ridge development through the Wnt5a/JNK pathway. Therefore, our studies uncover that the morphogenesis of the turtle carapace might function through the co-operation between conserved WNT and FGF signaling pathways. Consequently, our findings revealed the dynamic signaling pathways acting on the carapacial ridge development of Chinese soft-shell turtle and provided new insights into uncover the molecular mechanism underlying turtle shell morphogenesis.
33
Clark, George R., and Allen W. Archer. "Pliocene scallop growth lines: potential for environmental reconstruction and population dynamics." Paleontological Society Special Publications 6 (1992): 58. http://dx.doi.org/10.1017/s2475262200006183.
Full textAbstract:
Prominent growth ridges on the shell of the modern scallop Pecten diegensis are known to form with a daily periodicity. Pecten stearnsii, its direct ancestor, has the same growth ridges and would be expected to form them at the same rate.Pecten stearnsii specimens collected from the Pliocene Imperial Formation near San Filipe, Baja California, Mexico, have repetitive variations in the spacing of their growth ridges. Harmonic analysis of these variations found three tidal periodicities to be present, tropic (13.7 days), synodic (14.8 days), and anomalistic (27.6 days). This observation also served to confirm the daily nature of the growth ridges.Tidal patterns at various locations within the present-day Gulf of California are dominated to various degrees by synodic and tropic periodicities. Comparisons of the growth-line records to modern tidal records by cross-correlation found a good match with a tidal station south of the collecting site, where the tropic periodicity dominates but the synodic periodicity is still important.An important aspect of this match is that a graph of cross-correlations at all possible overlaps shows a cycle of good correlations, with a period of six months between peaks. As this is a reflection of the resonance between tropic and synodic periodicities, the peaks would occur at the same times of year in the Pliocene as today. This makes it possible to relate each specimen's growth record to the calendar, although two alternate interpretations, six months apart, would exist.Two possible relationships would be of interest. First, if all the specimens had died at the same time of year it could mean a catastrophe, such as a severe storm. This was not the case, which is in itself a useful observation. Second, if all the specimens began their growth line record at the same time of year, it would suggest specific seasons for spawning and for spatfall. Here the evidence was more supportive; most specimens began forming growth ridges in either late March or late September, with perhaps a month's growth prior to the first growth ridge.If isotopic paleotemperature analysis can be applied to these shells, or to others with similar characteristics, new levels of resolution in both environmental reconstruction and paleopopulation analysis may be achieved.
34
Rohr, David M. "Middle Ordovician carrier shell Lytospira (Mollusca, Gastropoda) from Alaska." Journal of Paleontology 67, no. 6 (November 1993): 959–62. http://dx.doi.org/10.1017/s0022336000025269.
Full textAbstract:
The euomphalacean gastropod Lytospira gerulus n. sp. is described from the Middle Ordovician of west-central Alaska. The species is among the oldest known carrier shell specimens, and also shows evidence of repaired shell breakage; the breakage may have been the result of unsuccessful predation attempts. The interior of the shell shows an unusual spiral groove and ridges that may have been associated with the animal's retractor muscle. This internal groove may be an overlooked feature of all species of Lytospira.
35
Phung, Chee-Chean, Pooi-San Heng, and Thor-Seng Liew. "Land snails ofLeptopomaPfeiffer, 1847 in Sabah, Northern Borneo (Caenogastropoda: Cyclophoridae): an analysis of molecular phylogeny and geographical variations in shell form." PeerJ 5 (October 31, 2017): e3981. http://dx.doi.org/10.7717/peerj.3981.
Full textAbstract:
Leptopomais a species rich genus with approximately 100 species documented. Species-level identification in this group has been based on shell morphology and colouration, as well as some anatomical features based on small sample sizes. However, the implications of the inter- and intra-species variations in shell form to the taxonomy ofLeptopomaspecies and the congruency of its current shell based taxonomy with its molecular phylogeny are still unclear. There are fourLeptopomaspecies found in Sabah, Borneo, and their taxonomy status remains uncertain due to substantial variation in shell forms. This study focuses on the phylogenetic relationships and geographical variation in shell form of threeLeptopomaspecies from Sabah. The phylogenetic relationship of these species was first estimated by performing Maximum Likelihood and Bayesian analysis based on mitochondrial genes (16S rDNA and COI) and nuclear gene (ITS-1). Then, a total of six quantitative shell characters (i.e., shell height, shell width, aperture height, aperture width, shell spire height, and ratio of shell height to width) and three qualitative shell characters (i.e., shell colour patterns, spiral ridges, and dark apertural band) of the specimens were mapped across the phylogenetic tree and tested for phylogenetic signals. Data on shell characters ofLeptopoma sericatumandLeptopoma pellucidumfrom two different locations (i.e., Balambangan Island and Kinabatangan) where both species occurred sympatrically were then obtained to examine the geographical variations in shell form. The molecular phylogenetic analyses suggested that each of the threeLeptopomaspecies was monophyletic and indicated congruence with only one of the shell characters (i.e., shell spiral ridges) in the current morphological-based classification. Although the geographical variation analyses suggested some of the shell characters indicating inter-species differences between the twoLeptopomaspecies, these also pointed to intra-species differences between populations from different locations. This study onLeptopomaspecies is based on small sample size and the findings appear only applicable toLeptopomaspecies in Sabah. Nevertheless, we anticipate this study to be a starting point for more detailed investigations to include the other still little-known (ca. 100)Leptopomaspecies and highlights a need to assess variations in shell characters before they could be used in species classification.
36
Kim, Guk Hee, Jaeung Kim, and Sungchan Yun. "The role of viscosity ratio in Janus drop impact on macro-ridge structure." Physics of Fluids 34, no. 5 (May 2022): 052115. http://dx.doi.org/10.1063/5.0094402.
Full textAbstract:
An interaction of liquid and solid surfaces upon impact has made great progress in understanding the principle behind impinging compound drops, such as single-interface Janus and core–shell configurations, for controlling drop mobility on the surfaces. Despite advancement of recent technologies, fundamentals of how viscosity ratios of Janus drops affect post-impact dynamics on anisotropic surfaces are still unknown. Here, we numerically investigate the asymmetric impact dynamics of Janus drops on a non-wettable ridged surface to demonstrate the feasibility of the separation of the low-viscosity part from the high-viscosity part by reducing the residence time. The separation is investigated for various viscosity ratios, Weber numbers ( We), and initial angle, which are discussed in terms of the temporal evolution of the mass and momentum distributions. A regime map for the separation reveals that the low-viscosity parts are more likely to be separated from high-viscosity parts as the viscosity ratio increases. The phenomenon can be related to a retraction time, which is explained by a hydrodynamic model for the low-viscosity part. This study suggests that We thresholds for the separation can be significantly reduced with the help of center-assisted retraction along the ridge. The asymmetric bouncing of Janus drops on a ridged surface can open up possibilities for the efficient control of liquid separation.
37
Gomez, Michael, Derek E. Moulton, and Dominic Vella. "The shallow shell approach to Pogorelov's problem and the breakdown of ‘mirror buckling’." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2187 (March 2016): 20150732. http://dx.doi.org/10.1098/rspa.2015.0732.
Full textAbstract:
We present a detailed asymptotic analysis of the point indentation of an unpressurized, spherical elastic shell. Previous analyses of this classic problem have assumed that for sufficiently large indentation depths, such a shell deforms by ‘mirror buckling’—a portion of the shell inverts to become a spherical cap with equal but opposite curvature to the undeformed shell. The energy of deformation is then localized in a ridge in which the deformed and undeformed portions of the shell join together, commonly referred to as Pogorelov's ridge. Rather than using an energy formulation, we revisit this problem from the point of view of the shallow shell equations and perform an asymptotic analysis that exploits the largeness of the indentation depth. This reveals first that the stress profile associated with mirror buckling is singular as the indenter is approached. This consequence of point indentation means that mirror buckling must be modified to incorporate the shell's bending stiffness close to the indenter and gives rise to an intricate asymptotic structure with seven different spatial regions. This is in contrast with the three regions (mirror-buckled, ridge and undeformed) that are usually assumed and yields new insight into the large compressive hoop stress that ultimately causes the secondary buckling of the shell.
38
MIZUKOSHI, Yuki, and Masatoshi SHIMODA. "Shape Optimization Method for Designing Ridges on Shell Structure." Proceedings of Design & Systems Conference 2019.29 (2019): 2103. http://dx.doi.org/10.1299/jsmedsd.2019.29.2103.
Full text
39
Baires, Sarah E. "A Microhistory of Human and Gastropod Bodies and Souls During Cahokia's Emergence." Cambridge Archaeological Journal 27, no. 2 (November 21, 2016): 245–60. http://dx.doi.org/10.1017/s095977431600055x.
Full textAbstract:
This article examines the role of mortuary practice in the emergence (c. ad 1050–1100) of Cahokia, the largest pre-Columbian Native American city north of Mexico. The parallel partitioning of human and gastropod bodies in ridge-top mortuary mounds is examined and I argue that the presence of gastropods buried alongside human bodies served to connect the living world of humans with the watery underworld of the dead. From a microhistorical perspective, this paper focuses on the processing and deposition of bodies and their subsequent interment in ridge-top burials to parse the potential relationships between such mortuary practice and Cahokia's emergence as a complex polity. The paper presents data on the association of shell materials with human bodies from six previously excavated ridge-tops for comparison with new data on shell materials and human burials from Wilson Mound, a small ridge-top located on the western edge of Cahokia. Together, these data suggest the emergence of Cahokia was embedded in newly articulated relationships with persons enacted through the process of disarticulating the dead for burial mediated with mollusc shell.
40
Moro, Alan, and Vlasta Ćosović. "A Proposal for Taxonomic Re-Evaluation of Vaccinites Species from the Santonian Limestones of Southern Istria (Croatia)." Geologia Croatica 57, no. 2 (2004): 139–47. http://dx.doi.org/10.4154/gc.2004.11.
Full textAbstract:
Rudists, especially members of the family Hippuritidae, were commondwellers on the Adriatic Carbonate Platform during the LateCretaceous. Morphological elements (ligamental ridge, teeth, pillars,length of the contour around the inner margin of the outer shell layerand the ratio between this length and the distance between the suturesof the pillars) from the transverse shell sections permit different speciesto be defined within the family. Transverse sections of Vaccinitesspecimens from the Santonian limestones in southern Istria show differentvalues of the angle between the teeth and the ligament ridge,between the ligamental ridge and the E pillar (P2), and of the ratiobetween the length of the contour and the pillar suture distance. Clusteranalyses (Ward’s and Unweighted pair–group average methods)using measured elements, allowed the definition of three speciesgroups from seventeen species at the beginning of study.
41
Yang, Jiayu, Yingying Xia, Shaohu Li, Tingting Chen, Jilong Zhang, Zhiyuan Weng, Huiwei Zheng, et al. "Gene Regulation during Carapacial Ridge Development of Mauremys reevesii: The Development of Carapacial Ridge, Ribs and Scutes." Genes 13, no. 9 (September 19, 2022): 1676. http://dx.doi.org/10.3390/genes13091676.
Full textAbstract:
The unique topological structure of a turtle shell, including the special ribs–scapula relationship, is an evolutionarily novelty of amniotes. The carapacial ridge is a key embryonic tissue for inducing turtle carapace morphologenesis. However, the gene expression profiles and molecular regulatory mechanisms that occur during carapacial ridge development, including the regulation mechanism of rib axis arrest, the development mechanism of the carapacial ridge, and the differentiation between soft-shell turtles and hard-shell turtles, are not fully understood. In this study, we obtained genome-wide gene expression profiles during the carapacial ridge development of Mauremys reevesii using RNA-sequencing by using carapacial ridge tissues from stage 14, 15 and 16 turtle embryos. In addition, a differentially expressed genes (DEGs) analysis and a gene set enrichment analysis (GSEA) of three comparison groups were performed. Furthermore, a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was used to analyze the pathway enrichment of the differentially expressed genes of the three comparative groups. The result displayed that the Wnt signaling pathway was substantially enriched in the CrTK14 vs. the CrTK15 comparison group, while the Hedgehog signaling pathway was significantly enriched in the CrTK15 vs. the CrTK16 group. Moreover, the regulatory network of the Wnt signaling pathway showed that Wnt signaling pathways might interact with Fgfs, Bmps, and Shh to form a regulatory network to regulate the carapacial ridge development. Next, WGCNA was used to cluster and analyze the expression genes during the carapacial ridge development of M. reevesii and P. sinensis. Further, a KEGG functional enrichment analysis of the carapacial ridge correlation gene modules was performed. Interesting, these results indicated that the Wnt signaling pathway and the MAPK signaling pathway were significantly enriched in the gene modules that were highly correlated with the stage 14 and stage 15 carapacial ridge samples of the two species. The Hedgehog signaling pathway was significantly enriched in the modules that were strongly correlated with the stage 16 carapacial ridge samples of M. reevesii, however, the PI3K-Akt signaling and the TGF-β signaling pathways were significantly enriched in the modules that were strongly correlated with the stage 16 carapacial ridge samples of P. sinensis. Furthermore, we found that those modules that were strongly correlated with the stage 14 carapacial ridge samples of M. reevesii and P. sinensis contained Wnts and Lef1. While the navajo white 3 module which was strongly correlated with the stage 16 carapacial ridge samples of M. reevesii contained Shh and Ptchs. The dark green module strongly correlated with the stage 16 carapacial ridge samples of P. sinensis which contained Col1a1, Col1a2, and Itga8. Consequently, this study systematically revealed the signaling pathways and genes that regulate the carapacial ridge development of M. reevesii and P. sinensis, which provides new insights for revealing the molecular mechanism that is underlying the turtle’s body structure.
42
Alibardi, Lorenzo, and Michael B. Thompson. "Morphogenesis of shell and scutes in the turtle Emydura macquarii." Australian Journal of Zoology 47, no. 3 (1999): 245. http://dx.doi.org/10.1071/zo99001.
Full textAbstract:
Formation of the scutes and dermis of the embryonic shell of the turtle Emydura macquarii was studied using light and electron microscopy. Shell morphogenesis begins at embryonic stage 15 and the shape of the shell is mostly completed by embryonic stage 19. The carapace anlagen arises as a thickening of the skin in the dorsal part of the mid-trunk region between the anterior and posterior limbs. This thickening extends ventro-laterally to form ridges at the margins of the carapace. Each ridge forms as a thick epidermal placode over a condensation of mesenchymal cells. The epidermis behind the advancing margins of the carapace is cuboidal or columnar but does not form placodes. The margins of the carapace expand rapidly in all directions. The plastron anlagen is derived from epidermal cells localised in the latero-ventral regions between the fore- and hind-limbs. Plastron placodes are present laterally, while the mid-ventral and central epidermis remains cuboidal or columnar but does not form placodes at embryonic stage 16. The plastron thickening rapidly moves from a latero-ventral position to a flat ventral position between embryonic stages 16 and 19. Dermal–epidermal anchoring complexes occur throughout placodes of both the carapace and plastron, but are rare in non-placode areas. The accumulation of a dense mesenchyme beneath the shell epidermis forms a dermal cushion that surrounds the body cavity. The superficial dermis close to the epidermis is made of mesenchymal fibroblasts at embryonic stage 19, although the inner-most areas contain bipolar fibroblasts and extracellular fibrils. Scutes with serrations at their borders form as invaginations of the epidermis into the dermis in the mid-dorsal areas of the embryo at embryonic stages 18–19. Dermal–epidermal anchoring complexes are located around the infoldings that form the scutes of the hinge region. The epidermis of the shell has 2–3 suprabasal cells at embryonic stages 19–22, and lacks keratinisation before embryonic stage 22 when it has 4–6 suprabasal layers with 2–3 external layers made of flat cells. The dermis thickens and has numerous collagen fibrils after embryonic stage 19. The formation of dermal bones begins at embryonic stage 18–19 in the plastron. Only small areas of the carapace near to the bridge have begun to form dermal bone at embryonic stage 19. Calcification begins at embryonic stage 19, but is still incomplete at embryonic stages 24–25.
43
Rengel, Miriam, Klaus Hodapp, and Jochen Eislöffel. "SK 1: A possible case of triggered star formation in perseus." Proceedings of the International Astronomical Union 2, S237 (August 2006): 217–21. http://dx.doi.org/10.1017/s1743921307001500.
Full textAbstract:
AbstractAccording to a triggered star formation scenario (e.g. Martin-Pintado & Cernicharo 1987) outflows powered by young stellar objects shape the molecular clouds, can dig cavities, and trigger new star formation. NGC 1333 is an active site of low- and intermediate star formation in Perseus and is a suggested site of self-regulated star formation (Norman & Silk 1980). Therefore it is a suitable target for a study of triggered star formation (e.g. Sandell & Knee 2001, SK1). On the other hand, continuum sub-mm observations of star forming regions can detect dust thermal emission of embedded sources (which drive outflows), and further detailed structures.Within the framework of our wide-field mapping of star formation regions in the Perseus and Orion molecular clouds using SCUBA at 850 and 450 μm, we mapped NCG 1333 with an area of around 14′× 21′. The maps show more structure than the previous maps of the region observed in sub-mm. We have unveiled the known embedded SK 1 source (in the dust shell of the SSV 13 ridge) and detailed structure of the region, among some other young protostars.In agreement with the SK 1 observations, our map of the region shows lumpy filaments and shells/cavities that seem to be created by outflows. The measured mass of SK 1 (~0.07 M) is much less than its virial mass (~0.2-1 M). Our observations support the idea of SK 1 as an event triggered by outflow-driven shells in NGC 1333 (induced by an increase in gas pressure and density due to radiation pressure from the stellar winds that have presumably created the dust shell). This kind of evidences provides a more thorough understanding of the star formation regulation processes.
44
Lyson, Tyler R., and Walter G. Joyce. "A new species of Palatobaena (Testudines: Baenidae) and a maximum parsimony and Bayesian phylogenetic analysis of Baenidae." Journal of Paleontology 83, no. 3 (May 2009): 457–70. http://dx.doi.org/10.1666/08-172.1.
Full textAbstract:
New Palatobaena material from the Hell Creek Formation (Maastrichtian), including the first skull and shell association, from southwestern North Dakota represents a new species named herein Palatobaena cohen. the material consists of 4 skulls, 2 lower jaws, and 2 shells and represents a true biological population (spatially and temporally restricted), which provides unprecedented access to ontogenetic and other intraspecific variation found in this taxon. the skull's round shape and lack of a lingual ridge on the greatly expanded triturating surface indicate its Palatobaena affinities, but it differs from both previously existing Palatobaena taxa in a number of features. the addition of shell characters to the most inclusive baenid phylogenetic analyses (Maximum parsimony and Bayesian) to date indicate that Pa. cohen is sister taxon to the other Palatobaena taxa. Notably, both the maximum parsimony analysis and Bayesian analysis provide strong support for Plesiobaena antiqua as sister to the Palatobaena clade. in addition, both analyses provide strong support for Stygiochelys estesi as sister to the Eocene clade of Baena arenosa and Chisternon undatum, which significantly reduces this clades' ghost lineage. the baenid topology reveals a demonstrably homoplastic trend towards the reduction of the temporal emargination and unique thickening of the posterior portion of the parietals that corresponds with the K/T boundary and is hypothesized to have provided limited protection from increasingly effective mammalian predators.
45
Søndergaard, Niels, and David J. Chappell. "Ray and wave scattering in smoothly curved thin shell cylindrical ridges." Journal of Sound and Vibration 377 (September 2016): 155–68. http://dx.doi.org/10.1016/j.jsv.2016.05.019.
Full text
46
Gan, Zhibin, Dongsheng Zhang, Xinzheng Li, and Chunsheng Wang. "Gibbosaverruca weijiai, a new verrucid (Crustacea, Thoracica) species from the Weijia Guyot deep-sea seamount in the West Pacific." European Journal of Taxonomy 739 (March 18, 2021): 158–67. http://dx.doi.org/10.5852/ejt.2021.739.1273.
Full textAbstract:
A new species of verrucid barnacle, Gibbosaverruca weijiai sp. nov., is described and illustrated based on specimens collected from a deep-sea seamount, Weijia Guyot, in the West Pacific. This is the third barnacle species reported from Weijia Guyot. The new species is distinguished from its congeners by its extremely long caudal appendage. In terms of shell morphology, G. weijiai sp. nov. is most similar to G. gibbosa and G. sulcata but differs from them by the intermediate articular ridges of its movable tergum and scutum, which are distinctly wider than the axial ridges. The COI and 16S rRNA sequences of the holotype of G. weijiai sp. nov. are presented to support future research, and a key to extant species of the genus Gibbosaverruca Young, 2002 is provided.
47
Al-Rashed, Rashed, Francisco López Jiménez, Joel Marthelot, and Pedro M. Reis. "Buckling patterns in biaxially pre-stretched bilayer shells: wrinkles, creases, folds and fracture-like ridges." Soft Matter 13, no. 43 (2017): 7969–78. http://dx.doi.org/10.1039/c7sm01828b.
Full text
48
Xie, Wenjun, Yanyun Zhao, Zhidong Zhang, Qing Liu, Jiangbao Xia, Jingkuan Sun, Jiayi Tian, and Tongqiu Sun. "Shell sand properties and vegetative distribution on shell ridges of the Southwestern Coast of Bohai Bay." Environmental Earth Sciences 67, no. 5 (February 4, 2012): 1357–62. http://dx.doi.org/10.1007/s12665-012-1578-2.
Full text
49
Mookerjea, Bhaswati. "Star Formation Triggered by the Expanding Bubble S111." Astrophysical Journal 926, no. 1 (February 1, 2022): 4. http://dx.doi.org/10.3847/1538-4357/ac4258.
Full textAbstract:
Abstract This paper investigates the impact of radiative and mechanical feedback from O-type stars on their parent molecular clouds and the triggering of formation of a future generation of stars. We study the infrared bubble S111 created by the embedded massive stellar cluster G316.80–0.05. A significant fraction of gas in shells created due to the compression of the ambient medium by expanding bubbles is photodissociated by the stellar radiation. The kinematics of the shells are thus best studied using spectroscopic observations of singly ionized carbon, the most dominant species. We have used velocity-resolved maps of the 2P3/2 → 2P1/2 transition of [C ii] at 158 μm, the J = 2–1 transition of 13CO and C18O, and the J = 1–0 transition of HCO+ to study the rim of the bubble S111 that partly coincides with the southern part of the infrared dark ridge G316.75. The [C ii] spectra conclusively show evidence of a shell expanding with a moderate velocity of ∼7 km s−1, which amounts to a kinetic energy that is ∼0.5–40 times the thermal energy of the H ii region. The pressure causing the expansion of the H ii region arises mainly from hydrogen ionization and dust-processed radiation. Among the far-infrared sources located in compressed shells, we find the core G316.7799–0.0942 to show broad spectral features consistent with outflow activity and conclude that it is a site of active star formation. Based on the age of the H ii region we conclude that this expanding H ii region is responsible for triggering the current star formation activity in the region.
50
Iancu, Stefania Andrada, Daniel Referendaru, Ilinca-Antigona Iancu, Anamaria Bechir, and Horia Mihail Barbu. "Immediate postoperative complications after lateral ridge augmentation – a clinical comparison between bone shell technique and sticky bone." Journal of Medicine and Life 15, no. 4 (April 2022): 533–38. http://dx.doi.org/10.25122/jml-2021-0347.
Full textAbstract:
Nowadays, implant dentistry is strongly interconnected to bone augmentation procedures. Lateral ridge augmentation is often an imperative treatment stage for successful, prosthetic-driven implant placement. This study aimed to comparatively analyze the immediate postoperative complications of two horizontal bone grafting procedures: sticky bone and bone shell technique. Records of patients with lateral ridge augmentation were analyzed to identify immediate postoperative complications. The study group included 80 patients divided into 40 control (bone-shell technique – BS) and 40 tests (sticky bone –SB). More patients reported moderate and severe pain in the BS – group (11 patients – 27.5%) than in the SB group (6 patients – 15%). In the BS group, the incidence of severe and moderate trismus, neurosensory disturbances, and important hematoma was higher. There was an increased inflammatory response following the bone shell technique, while the sticky bone technique proved reduced surgical morbidity. There was no difference between the two groups in the risk of dehiscence or infection.