Shell Production Research Articles

Biomineralization plasticity and environmental heterogeneity predict geographical resilience patterns of foundation species to future change.

Although geographical patterns of species' sensitivity to environmental changes are defined by interacting multiple stressors, little is known about compensatory processes shaping regional differences in organismal vulnerability. Here, we examine large-scale spatial variations in biomineralization under heterogeneous environmental gradients of temperature, salinity and food availability across a 30° latitudinal range (3,334km), to test whether plasticity in calcareous shell production and composition, from juveniles to large adults, mediates geographical patterns of resilience to climate change in critical foundation species, the mussels Mytilus edulis and M.trossulus. We find shell calcification decreased towards high latitude, with mussels producing thinner shells with a higher organic content in polar than temperate regions. Salinity was the best predictor of within-region differences in mussel shell deposition, mineral and organic composition. In polar, subpolar, and Baltic low-salinity environments, mussels produced thin shells with a thicker external organic layer (periostracum), and an increased proportion of calcite (prismatic layer, as opposed to aragonite) and organic matrix, providing potentially higher resistance against dissolution in more corrosive waters. Conversely, in temperate, higher salinity regimes, thicker, more calcified shells with a higher aragonite (nacreous layer) proportion were deposited, which suggests enhanced protection under increased predation pressure. Interacting effects of salinity and food availability on mussel shell composition predict the deposition of a thicker periostracum and organic-enriched prismatic layer under forecasted future environmental conditions, suggesting a capacity for increased protection of high-latitude populations from ocean acidification. These findings support biomineralization plasticity as a potentially advantageous compensatory mechanism conferring Mytilus species a protective capacity for quantitative and qualitative trade-offs in shell deposition as a response to regional alterations of abiotic and biotic conditions in future environments. Our work illustrates that compensatory mechanisms, driving plastic responses to the spatial structure of multiple stressors, can define geographical patterns of unanticipated species resilience to global environmental change.

Evolution and diversity of alpha-carbonic anhydrases in the mantle of the Mediterranean mussel (Mytilus galloprovincialis)

The α-carbonic anhydrases (α-CAs) are a large and ancient group of metazoan-specific enzymes. They generate bicarbonate from metabolic carbon dioxide and through calcium carbonate crystal formation play a key role in the regulation of mineralized structures. To better understand how α-CAs contribute to shell mineralization in the marine Mediterranean mussel (Mytilus galloprovincialis) we characterized them in the mantle. Phylogenetic analysis revealed that mollusc α-CA evolution was affected by lineage and species-specific events. Ten α-CAs were found in the Mediterranean mussel mantle and the most abundant form was named, MgNACR, as it grouped with oyster nacreins (NACR). Exposure of the Mediterranean mussel to reduced water salinity (18 vs 37 ppt), caused a significant reduction (p < 0.05) in mantle esterase activity and MgNACR transcript abundance (p < 0.05). Protonograms revealed multiple proteins in the mantle with α–CA hydratase activity and mapped to a protein with a similar size to that deduced for monomeric MgNACR. Our data indicate that MgNACR is a major α–CA enzyme in mantle and that by homology with oyster nacreins likely regulates mussel shell production. We propose that species-dependent α-CA evolution may contribute to explain the diversity of bivalve shell structures and their vulnerability to environmental changes.

A high-resolution perspective on MIS 5c-d lithic assemblages from Klasies River main site Cave 1

Klasies River contains an extensive MIS 5 MSA sequence, mostly from what has been described as the MSA ll, MSA 2a or the Mossel Bay techno-complex. The current Witness Baulk excavations undertaken between 2015 and 2016 allows for a renewed and detailed investigation of the variability of the lithic technology from the lowermost part of the MSA ll. This assemblage is equivalent to Deacon's SASL sub-member and Layers 17a and b of Singer and Wymer. Two phases are recognized: An MIS 5c phase in layer SMONE (Singer & Wymer layer 17a) and an MIS 5d phase in layers BOS One and BOS Two (Singer & Wymer layer 17 b). The two phases are characterized by commonalities such as a focus on quartzite utilisation, the presence of a main unidirectional reduction system, similar end products which comprise of points, blades and flakes and a low amount of formal tools. However, this high-resolution investigation of the layers reveals temporal variability. In the Shell Midden ONE (SMONE) layer cores and products are relatively lighter and small debitage is more frequent. There are more flake end products and compared to the lower layer, there are fewer tool types. In the Black Occupational Soil (BOS) layer points and blades are more numerous, products are heavier, core types are more variable, and a higher frequency and variety of tool types occur. Such detailed differences within the MIS 5 assemblages from Klasies River, not described before, shows that the MSA ll is not a homogeneous entity, and that subtle patterning occurs that may link to different technological strategies. Compared to other MIS 5 sites on the southern Cape, namely Blombos Cave, Pinnacle Point and Cape St. Blaize, a common pattern in place provisioning is seen, although the technology shows differences between the sites. This study indicates the value of more detailed studies of MIS 5 assemblages as a tool to understand variability from a more refined perspective.

Evolutionary Algorithm for Aerospace Shell Product Digital Production Line Scheduling Problem

The production of aerospace shell products is directly related to the safety and reliability of aerospace products. In this work, the aerospace shell product digital production line scheduling problem (ASPDPLSP) was studied, and a solution was developed. In the production process, it is necessary to decide the processing machine and time of each operation. In order to create a scientific shell product production plan, we propose an operation scheduling algorithm (OSA). Based on the constraints of the inspection process, the OSA has two heuristic task scheduling rules. Then, in order to further optimize the product production plan, an improved genetic algorithm (IGA) is proposed. Considering the repeatability caused by random search, a method for the initial population generation with similar and diverse characteristics is proposed. Two of these generation rules retain symmetry and randomness. IGA was used to optimize the order in which the products were processed, resulting in lower costs. Simulation experiments showed that the proposed algorithm solved ASPDPLSP well and provided suggestions to produce aerospace shell products.

Application of the Glass-Metal Composite Made by Spin Casting Method for Pressure Hulls of Deep-Sea Submersibles

In this work the manufacturing techniques of layered constructional material metal-glass-metal by method of centrifugal casting are considered. The scheme of installation for production of cylindrical shells from a glass-metal composite is provided, the research of the main technological modes providing reliable connection of aluminium coverings with the glass which is in a plastic state is conducted optimum values of temperature parameters are defined. Methods of electronic microscopy have investigated the diffusive layer which is formed on border glass-aluminium.

Pre-Design of Bio-Briquette Production Using Kenari Shell

At present, coconut shell charcoal briquettes are one of the alternative energy sources that are in demand by the export market. The purpose of this research was to produce an alternative briquette product based on local natural materials. Kenari shell is a waste of natural materials or biomass. The characteristics of Kenari shells have the same structure with coconut shell. The pre-design of briquette production of this Kenari shell used pre-treatment process stages, charcoal making, destruction, printing with adhesive variation, drying, and SNI quality of briquette quality analysis. The results of pre-design of bio-briquette production of Kenari shell showed that the application of the method and the basic ingredients of waste could produce the product of charcoal briquettes equal to charcoal briquettes of coconut shell.

Knowledge Co-production in Contested Spaces: An Evaluation of the North Slope Borough – Shell Baseline Studies Program

Supporting the development of trusted and usable science remains a key challenge in contested spaces. This paper evaluates a collaborative research agreement between the North Slope Borough of Alaska and Shell Exploration and Production Company—an agreement that was designed to improve collection of information and management of issues associated with the potential impacts of oil and gas development in the Arctic. The evaluation is based on six categories of knowledge co-production indicators: external factors, inputs, processes, outputs, outcomes, and impacts. Two sources of data were used to assess the indicators: interviews with steering committee members and external science managers (n = 16) and a review of steering committee minutes. Interpretation of the output and outcome indicators suggests that the Baseline Studies Program supported a broad range of research, though there were differences in how groups perceived the relevance and legitimacy of project outcomes. Several input, process, and external variables enabled the co-production of trusted science in an emergent boundary organization and contested space; these variables included governance arrangements, leveraged capacities, and the inclusion of traditional knowledge. Challenges to knowledge co-production on the North Slope include logistics, differences in cultures and decision contexts, and balancing trade-offs among perceived credibility, legitimacy, and relevance. Reinforced lessons learned included providing time to foster trust, developing adaptive governance approaches, and building capacity among scientists to translate community concerns into research questions.

The effect of aquaculture gear on the growth and shape of the oyster Crassostrea virginica during a “finishing period” in Chesapeake Bay, USA

Growth of the oyster aquaculture industry on the US east coast has accelerated in recent decades due to advances in breeding technologies and grow-out methods. As the industry grows, competition in the market place is likely to increase attention to product quality, for example, shell conformation and meat content. This study investigated how gear type and tidal zone location influenced shell shape and product quality of Crassostrea virginica during a four month “finishing” period at an oyster farm on Fishing Creek MD on the eastern shore of Chesapeake Bay. For these experiments, a mix of sub-market sized, triploid oysters from two local farms were deployed in four gear treatments that varied in water column location and exposure to wave action: OysterGro™ floats, a rack and bag system, a bottom cage placed in the intertidal, and a bottom cage placed subtidally, which represents the ‘control’ treatment (no change of gear type for finishing). Shell height, length, width, and weight (total and wet meat) were measured each month from August to December 2015 and an index of shell shape relative to an idealized 3-2-1 ratio of height to length to width was calculated. Overall, oysters grew well in all gear types (3.0–-4.8 mm increase in shell height per month) and experienced relatively low mortality (4–8% across treatments) – mean height of oysters from each gear treatment exceeded market size by the end of the experiment. Gear treatment had a significant effect on oyster height and weight at the end of the experiment (P < 2.0e–05) and the OysterGro™ treatment produced the largest gains in growth compared to all other treatments (2.3-2.5 fold– increase in wet or total weight). Gear type also affected shell shape (P = 0.023), with significantly lower mean 3-2-1 ratio deviations (more ideal, rounded shells) in the OysterGro™ compared to subtidal bottom cage or rack and bag gear. Shell shape improved the most between initial and final time points for the OysterGro™ treatment, while the rack and bag and bottom cage subtidal treatments showed no improvement. This study provides some of the first data on growth performance and shell shape using the OysterGro™ system in Chesapeake Bay and overall, results indicate that floating gear such as the OysterGro™ system may be a valuable method to finish oysters, facilitating good growth, and improving shape over a relatively short period of time.

Production and detachment of oxide crystal shells on bubble walls during experimental vesiculation of andesitic magmas

The mutual affinity between bubbles and oxide crystals (especially magnetite) is well established and their tendency to remain in contact once they become connected (either by nucleation of one upon the other, or by attachment) has led to models of oxide transport via bubbles in natural melts. However, despite the widespread acceptance of bubble–oxide association, there is little direct textural evidence for these processes. We present results from a series of decompression experiments on andesitic melts, during which aggregates of bubbles and oxides formed because of hydrogen loss through the capsule walls causing oxidation of the melt. Experimental charges were imaged using 3D X-ray computed tomography that revealed complex bubble + oxide aggregates, with small oxide crystals coating part of the outer bubble surfaces in a shell-like morphology. These shells have smooth inner and rugose outer surfaces. Sometimes, additional concentric shells or partial shells can be found around bubbles, in the glass between the bubble wall and another shell. We quantified the volumes of bubbles and oxides and the oxides’ compositions. We measured the surface area where the bubbles and oxides are in contact, thus quantifying their interface in 3D, and used these measurements to investigate the process of oxide shell formation. The complexity of the oxide textures when studied in 3D reveals a range of bubble–oxide interactions, from continuous generation, detachment and disintegration. These processes carry important implications on why such textures seem to have a low preservation potential in natural environments. Nevertheless, we have found natural samples that resemble our experimental results in a range of rock compositions from different geological environments that could have formed either due to rapid oxidation via the fluid phase or by bubbles harvesting different crystals.

Onshore and offshore evidences for four abrupt “warming” episodes during MIS 6 at the westernmost tip of continental Europe: did they control the migrations of Neanderthals?

The total shell production typical of the Pupilla association in the onshore site of Nantois (Brittany, France) evidenced for the first time four brief, abrupt, warm and humid episodes during the Upper Saalian (MIS 6) loess deposition. These “warming” events were also found in the marine deposits of the Celtic Sea (MD03-2692 core). Comparison with the variations of the sea-level, show that the “warming” episodes were not only of regional interest but corresponded to global events ruled by precession and insolation cycles. Other comparisons with biomarker records (mollusсs, charcoal and rodents) of the Paris Basin (Villiers-Adam) and Jersey Island (La Cotte de Saint Brolade) confirm the existence of these warmer events. Tentative correlations with the discontinuous Neanderthal dwelling phases recorded in Brittany suggest that these populations were mainly (only?) present in Westernmost Europe during the warmer episodes.

Effects of calcination on synthesis of hydroxyapatite derived from oyster shell powders

Oysters abound on the west coast of Taiwan and waste oyster shell production exceeds 0.12 million tons per year. The wide availability and natural-biological origin of oyster shells, containing several trace elements that will remain in the crystalline structure of synthesized HA making its composition alike human bone, will benefit the overall physiological functioning after implantation. In this study, solid-state reactions between oyster shell powders (CaCO3) and dicalcium phosphate dihydrate (DCPD) were performed through ball milling and subsequently calcining at various temperatures (900, 1000, 1100, and 1200 °C) and durations (1, 3, 5, and 10 h). The XRD results showed that we have successfully synthesized high phase-purity HA from DCPD and oyster shell powders through 1 h of milling and then calcined at 1000 °C for 10 h or at 1200 °C for 1 h. The crystallite size of as-prepared HA was around 45.3 nm, while the particle sizes were 2.23 and 2.59 μm, respectively. According to the FTIR analysis of as-prepared HA powders calcined at 1000 °C for 10 h or at 1200 °C for 1 h, the carbonate ion peaks observed for the specimen closely matched those of A- and B-type carbonates. It is worth noting that the final products composed of single-phase HA or biphasic calcium phosphate (HA+β-TCP) can easily be prepared by using different calcination temperatures and times, although we intended to produce pure HA from oyster shell powders.

Sediment contributing invasive dreissenid species in a calcareous shallow lake – Possible implications for shortening life span of lakes by filling

Although the ecosystem transforming impact of the invasive dreissenid mussels has been widely reported in short-to-mid time scale studies, little is known about the contribution of the spent shells to sediments accumulating on the lake bottom. The question whether the shell production significantly reduces the lifespan of the lake by increasing sedimentation rate is particularly interesting in those shallow lakes where the calcium supply is sufficient to maintain the high mussel biomass production permanently, and where the alkaline water does not favor shell dissolution. Lake Balaton, a large calcareous, shallow lake in Central Europe invaded by dreissenids (Dreissena polymorpha, Dreissena rostriformis bugensis), provides an ideal testing ground for this scenario. Therefore, we made calculations based on recent population abundance datasets (2000–2018), estimated the whole habitable, hard surface coastline and the muddy bottom of the pelagic area which is also gradually becoming inhabited by D. r. bugensis, using high resolution aerial photographs and analyzing seismic sections. We created four scenarios: (1) if no dreissenids are present (applying basic sedimentation rate); (2) if D. r. bugensis had not been introduced to the lake (only D. polymorpha); (3) if D. r. bugensis occupies the hard surfaces of the coastline (the current dominant situation); (4) if D. r. bugensis colonizes the entire lake bottom (a probable future model). Different sedimentation rates obtained from the literature were used to model the filling of Lake Balaton. The shell production of the new invader, D. r. bugensis can shorten the lake’s lifespan by one to two-thirds, depending on the model, and whether the mussel density currently observed at the shoreline is extended to the whole lake bottom. Attention is called to shallow calcareous lakes with low pre-invasion sedimentation rates in which the shell contribution of invasive mollusks has the potential to shorten lifespan.

Customer Satisfaction Survey on Sunflower Shell Waste Animal Feed Pellet

Abstract The purpose of this study is to investigate customer satisfaction toward the newly formulated sunflower shell waste-based animal feed pellet (PI2019002187). Survey was conducted through internet-based platform that is provided through QR code to trial participants with mix Likert scale questionnaires and opinion-based questionnaires. The surveys finding indicate that most participants rated the products is good value for money (50%). About half of the respondent rate the product as high quality meanwhile approximately 78.6% rate that the product is met their pet feeding requirement very well. Overall, more than 2/3 of the participants is somewhat satisfied with the product and provide positive feedback on their intention on re-purchasing and recommending the product to their family, friends and colleague. ANOVA analysis were further performed on the survey data and it display a significant correlation of customer satisfaction with sunflower shell waste-based pellet pet feeding requirement, product quality and money value as well as it effect toward behavioural intention on re-purchasing and recommendation.

运载火箭筒体壳段自动铆接路径的仿真优化分析

运载火箭筒体壳段自动铆接路径的仿真优化分析

Modelling seawater carbonate chemistry in shellfish aquaculture regions: Insights into CO2 release associated with shell formation and growth

Mollusc aquaculture is a high-value industry that is increasing production rapidly in Europe and across the globe. In recent years, there has been discussion of the potential wide-ranging environmental benefits of this form of food production. One aspect of mollusc aquaculture that has received scrutiny is the production of calcareous shells (CaCO3). Mollusc shell growth has sometimes been described as a sink for atmospheric CO2, as it locks away carbon in solid mineral form. However, more rigorous carbonate chemistry modelling, including concurrent changes in seawater pCO2, pH, dissolved inorganic carbon, and total alkalinity, shows that calcification is a net CO2 source to the atmosphere. Combined with discussions about whether mollusc respiration should be included in carbon footprint modelling, this suggests that greater in-depth understanding is required before shellfish aquaculture can be included in carbon trading schemes and footprint calculations. Here, we show that regional differences in the marine carbonate system can alter the amount of CO2 released per unit CaCO3 formation. Our carbonate chemistry modelling shows that a coastal mussel farm in southern Portugal releases up to ~0.290 g of CO2 per g of CaCO3 shell formed. In comparison, an identical farm in the coastal Baltic Sea would produce up to 33% more CO2 per g of CaCO3 (~0.385 g-CO2·(g-CaCO3)−1). This spatial variability should therefore also be considered if mollusc aquaculture is to be included in future carbon trading schemes, and in planning future expansion of production across the industry.

Layout Optimization of Flexible Manufacturing Cells Based on Fuzzy Demand and Machine Flexibility

Layout flexibility is critical for the performance of flexible manufacturing cells, especially in dynamic production environment. To improve layout flexibility, layout optimization should consider more flexible factors based on existed models. On the one hand, not only should the current production demands be covered, but also the future uncertain demands should be considered so that the cell can adapt to the dynamic changes in a long term. On the other hand, the flexibility of machines should be balanced in the layout in order to guarantee that the cell can deal with dynamic new product introduction. Starting from these two points, we formulate a layout optimization model based on fuzzy demand and machine flexibility and then develop a genetic algorithm with bilayer chromosome to solve the model. We apply this new model to a flexible cell of shell products and test its performance by comparing it with the classical two-stage model. The total logistics path of the new model is shown to be significantly shorter than the classical model. Then we carry out adaptability experiments to test the flexibility of the new model. For the dynamic situation of both the fluctuation of production demands and the introduction of new products, the new model shows obvious advantages to the classical model. The results indicate that this advantage becomes greater as the dynamics becomes greater, which implies that considering fuzzy demand and machine flexibility is necessary and reasonable in layout optimization, especially when the dynamics of the production environment is dramatic.

Recycling Cullet from Quartz Ceramic Shells Used in Investment Casting

The use of low-temperature quartz modifications in pulverized form creates additional risks in the manufacture of molds, since polymorphic transformations decrease their crack resistance. In practice, individual layers of the shell wall or the mold as a whole often crack and even disintegrate. In many casting shops, the lining is preliminarily roasted. That may somewhat improve the consequences of polymorphic transformations in the quartz, but steady heating of the molds through the filler to reduce the odds of cracking prolongs the process and increases the energy consumption. The best-known approach to minimizing the cracking and disintegration of shell molds on roasting is to replace the filler: instead of quartz dust, it is possible to use disperse quartz sand of polyfractional composition, sillimanite, pulverized alumosilicate, globular corundum, or fused quartz. However, those materials are expensive and their use is inconsistent with the requirements of resource conservation in casting. A possible material might be silica-based ceramic cullet from the shells used in steel and aluminum investment casting. At present, such cullet is not recycled. It is dumped or used as filler in the flasks used for shaping shells. Chemical and phase analysis shows that the ceramic cullet formed after removing the steel and aluminum castings contains not only quartz and high-temperature tridymite and cristobalite phases (the base) but also 5–10% iron and iron scale and 3–5% aluminum and its oxides. The use of such ceramic cullet in shell production eliminates repeated polymorphic transformation of the quartz in roasting and sealing the molds, which would change the volume, density, and crystal lattice of the material. That increases the crack resistance and strength of the shells and minimizes the waste of the castings produced. Residual iron and aluminum and their oxides improve the utility of the mold. Tests of this recycling method in production conditions confirm its effectiveness.

4. Improvement of techniques of seedling production of pen shell in Fisheries Research and Education Agency

4. Improvement of techniques of seedling production of pen shell in Fisheries Research and Education Agency

Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system

Research Article| August 08, 2018 Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system J.L. Pickering; J.L. Pickering † 1Department of Earth and Environmental Science, Vanderbilt University, Nashville, Tennessee 37235, USA †Present address: Shell International Exploration and Production, Inc., Houston, Texas 77082, USA; jennifer.pickering@shell.com. Search for other works by this author on: GSW Google Scholar M.S. Diamond; M.S. Diamond 1Department of Earth and Environmental Science, Vanderbilt University, Nashville, Tennessee 37235, USA Search for other works by this author on: GSW Google Scholar S.L. Goodbred; S.L. Goodbred 1Department of Earth and Environmental Science, Vanderbilt University, Nashville, Tennessee 37235, USA Search for other works by this author on: GSW Google Scholar C. Grall; C. Grall 2Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar J.M. Martin; J.M. Martin 3Shell International Exploration and Production, Inc., Houston, Texas 77082, USA Search for other works by this author on: GSW Google Scholar L. Palamenghi; L. Palamenghi 4Faculty of Geosciences, University of Bremen, Bremen 28359, Germany Search for other works by this author on: GSW Google Scholar C. Paola; C. Paola 5Department of Earth Sciences and St. Anthony Falls Laboratory, University of Minnesota, Minneapolis, Minnesota 55455, USA Search for other works by this author on: GSW Google Scholar T. Schwenk; T. Schwenk 4Faculty of Geosciences, University of Bremen, Bremen 28359, Germany Search for other works by this author on: GSW Google Scholar R.S. Sincavage; R.S. Sincavage 1Department of Earth and Environmental Science, Vanderbilt University, Nashville, Tennessee 37235, USA Search for other works by this author on: GSW Google Scholar V. Spieß V. Spieß 4Faculty of Geosciences, University of Bremen, Bremen 28359, Germany Search for other works by this author on: GSW Google Scholar GSA Bulletin (2019) 131 (1-2): 58–70. https://doi.org/10.1130/B31941.1 Article history received: 08 Oct 2017 rev-recd: 02 Mar 2018 accepted: 15 Jun 2018 first online: 08 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation J.L. Pickering, M.S. Diamond, S.L. Goodbred, C. Grall, J.M. Martin, L. Palamenghi, C. Paola, T. Schwenk, R.S. Sincavage, V. Spieß; Impact of glacial-lake paleofloods on valley development since glacial termination II: A conundrum of hydrology and scale for the lowstand Brahmaputra-Jamuna paleovalley system. GSA Bulletin 2018;; 131 (1-2): 58–70. doi: https://doi.org/10.1130/B31941.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract To better define the base of the Brahmaputra River paleovalley, we analyzed an extensive borehole data set from the subaerial Bengal delta and a 255-km-long multichannel seismic survey along the modern river. The data reveal that the paleovalley floor is defined by a gravel unit containing boulder-sized clasts up to 30 cm in diameter, deposited after ca. 30 ka but before ca. 9 ka. Paleohydrology during that time and the previous glacial maximum was characterized by a weak monsoon and reduced river discharge, both of which are inconsistent with large valley formation. However, our work indicates that glacial-lake outburst floods sourced from the Tibetan reaches of the Brahmaputra were routed through the lowstand valley, producing megaflood-scale discharge capable of transporting gravel and cannibalizing the valley margins. The timing of these glacial-lake outburst flood–driven discharge events was coincident with valley development and explains the anomalously large width of the valley and basal gravel surface. Despite the underfit scale of Brahmaputra discharge following the last glacial period, a strengthening monsoon and high sediment discharge in the early Holocene subsequently contributed to the efficient infilling of the massive paleovalley by the mid-Holocene. In a sequence stratigraphic context, this work provides an example of a major unconformity that developed late in the eustatic cycle (i.e., during early transgression rather than an earlier, protracted response to sea-level lowering) and in response to a perturbation originating in the catchment instead of changing accommodation in the basin. As such, it represents a geologically instantaneous time surface that can be used as a marker for stratigraphic correlation but one that is not in phase with eustatic sea-level fall. You do not currently have access to this article.

MORTALITY, PRODUCTION AND QUALITY OF EGGS OF DIFFERENT REARING SYSTEMS

ABSTRACT The conventional production of eggs in cage systems is intense and compromises the laying hens welfare. More demanding consumer markets have been pushing to abolish the use of cages and thus provide better welfare in poultry laying. This research evaluated the mortality, production, and egg quality of two alternative production systems (free-range and organic free range free-range) and compared them with the conventional system. The research was carried out in two commercial poultry farms and the variables egg weight, shell egg resistance, Haugh unit, mortality and production were recorded during eight months. The results showed that the conventional system presented better production, lower mortality and better shell egg quality. The alternative systems had better internal egg quality. Alternative systems had greater variability in outcomes and problems with disease control, which indicate greater difficulty for proper management.