scholarly journals Mineralogy, Geochemistry and Provenance of Coastal Sands from Greece: New Insights on the REE Content of Black Coastal Sands from Aggelochori Area, N.-Greece

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 693
Author(s):  
Argyrios Papadopoulos ◽  
Stylianos Lazaridis ◽  
Afroditi Kipourou-Panagiotou ◽  
Nikolaos Kantiranis ◽  
Antonios Koroneos ◽  
...  
Keyword(s):  
Major And Trace Elements ◽  
Heavy Minerals ◽  
Sea Waves ◽  
Complex Flow ◽  
Fine Grained ◽  
Microscopy Analysis ◽  
Beach Sands ◽  
Geochemical Analyses ◽  
The One ◽  
Black Color

Beach sands from Aggelochori coast line are investigated for their geochemistry and REE content, mineralogy and their provenance. These fluvial sands bear heavy minerals enriched horizons (containing minerals such as magnetite, zircon, ilmenite, hematite, rutile and titanite) that can be distinguished due to their black color and are formed usually due to the action of sea waves that deposit the heavy minerals and remove the lighter ones. After a suitable processing (washing, sieving, drying and magnetic separation) of the samples, the mineral constituents and their presence (wt.%) were estimated by XRD. Among the samples, the one being simultaneously the more fine grained and the more zircon-enriched (as suggested by XRPD data and optical microscopy analysis) has been selected for further geochemical analyses. The major and trace elements contents were compared to previously studied REE enriched beach sands from Kavala and Sithonia. Beach sands from Aggelochori area appear to have relatively low REE contents. Considering the provenance of these sediments, we suggest that these sands, are a product of the erosion of multi-sources, including the near-by Monopigado granite, as well as metamorphic rocks, as indicated by the presence of rutile and both ilmenite and magnetite in some samples. Therefore, there are indications of a complex flow pattern that existed at the paleo-catchment area of the deposition.

Improving the Mechanical Properties of AZ31 Mg Alloy by High Ratio Extrusion

2006 ◽  
Vol 503-504 ◽  
pp. 865-870 ◽  
Author(s):  
Yongjun Chen ◽  
Qu Dong Wang ◽  
Jianguo Peng ◽  
Chun Quan Zhai
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
High Ratio ◽  
Extrusion Ratio ◽  
Mg Alloy ◽  
Fine Grained ◽  
Az31 Mg Alloy ◽  
Industry Applications ◽  
One Step ◽  
The One

Experiments were conducted both to evaluate the potential for grain refinement, the subsequent mechanical properties at room temperature in samples of AZ31 Mg alloy and also to investigate the relationship between one-step and two-step high ratio extrusion (HRE). The one-step HRE was undertaken using a high extrusion ratio of 70:1 at 250, 300 and 350°C. And the two-step HRE was conducted with an extrusion ratio of 7 for the first step at 250, 300 and 350°C, followed by a second-step extrusion with an extrusion ratio of 10 at 250, 300 and 350°C. The initial grain size in the AZ31 ingot was 100μm and that after one-step HRE became similar to 5μm, after two-step HRE at 250, 300 and 350°C were 2, 4, 7μm, respectively, resulting in superior mechanical properties at ambient temperature. The microstructure of two-step HRE was finer and uniformer than that of one-step HRE and the strength of one-step and two-step HRE were similar, moreover, the elongation of one-step HRE was improved markedly than that of two-step HRE. Dynamic recrystallization and adjacent grain broking during HRE is introduced to explain the effects of one-step and two-step HRE on the microstructure and mechanical properties of AZ31 Mg alloy. The current results imply that the simple HRE method might be a feasible processing method for industry applications, and the multiply steps extrusion are effective to fabricate high strength of fine grained hcp metals.

scholarly journals Additive-error fine-grained quantum supremacy

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 329
Author(s):  
Tomoyuki Morimae ◽  
Suguru Tamaki
Keyword(s):  
Quantum Computing ◽  
Complexity Theory ◽  
Polynomial Time ◽  
Boolean Circuits ◽  
Exponential Time ◽  
Fine Grained ◽  
Additive Error ◽  
Universal Quantum ◽  
The One ◽  
Computing Models

It is known that several sub-universal quantum computing models, such as the IQP model, the Boson sampling model, the one-clean qubit model, and the random circuit model, cannot be classically simulated in polynomial time under certain conjectures in classical complexity theory. Recently, these results have been improved to ``fine-grained" versions where even exponential-time classical simulations are excluded assuming certain classical fine-grained complexity conjectures. All these fine-grained results are, however, about the hardness of strong simulations or multiplicative-error sampling. It was open whether any fine-grained quantum supremacy result can be shown for a more realistic setup, namely, additive-error sampling. In this paper, we show the additive-error fine-grained quantum supremacy (under certain complexity assumptions). As examples, we consider the IQP model, a mixture of the IQP model and log-depth Boolean circuits, and Clifford+T circuits. Similar results should hold for other sub-universal models.

Dinosaur trackways from the Upper Cretaceous Oldman and Dinosaur Park formations (Belly River Group) of southern Alberta, Canada, reveal novel ichnofossil preservation style

2015 ◽  
Vol 52 (8) ◽  
pp. 630-641 ◽  
Author(s):  
François Therrien ◽  
Darla K. Zelenitsky ◽  
Annie Quinney ◽  
Kohei Tanaka
Keyword(s):  
Natural Area ◽  
Geochemical Composition ◽  
Fine Grained ◽  
Depositional Settings ◽  
Internal Structures ◽  
Southern Alberta ◽  
Dinosaur Tracks ◽  
Geochemical Analyses ◽  
Water Saturated ◽  
Mineralogical Compositions

Dinosaur tracksites recently discovered in exposures of the Belly River Group in the Milk River Natural Area (MRNA) and Dinosaur Provincial Park (DPP) of southern Alberta represent a novel type of ichnofossils. The tracks, all referable to hadrosaurs, occur as sideritic or calcareous concretions protruding above fine-grained deposits and are here termed concretionary tracks. Detailed sedimentological, petrographic, and geochemical analyses reveal that, although the MRNA and DPP tracks are of different mineralogical compositions (calcium carbonate versus siderite, respectively), they display similar internal structures (microscopic convoluted laminations) and occur in depositional settings indicative of wet paleoenvironments, where the ground was soft and water saturated. These characteristics suggest that concretionary tracks are footprint casts that formed as groundwater rich in dissolved carbonates flooded depressions left in the soft substrate. As the ponded water evaporated, minerals began to precipitate and mix with clastic material transported into the depressions, settling as finely laminated mud within the tracks and filling them either completely or partially. The geochemical composition of the precipitate would depend on the prevalent groundwater conditions (e.g., pH, dissolved carbonate and sulphate concrentrations). Cementation of the tracks occurred relatively soon after burial (<100 years), possibly in response to microbial activity and saturation by mineral-rich groundwater, and modern erosion exposed the concretionary tracks by removing the softer host unit. Recognition of this novel type of ichnofossils suggests dinosaur tracks may be more common than previously thought. Unfortunately, concretionary tracks tend to break apart rapidly when the encasing and underlying substrate erodes away, altering their diagnostic shape and rendering them indistinguishable from nonichnogenic concretions. As such, concretionary tracks may be transient ichnofossils in the badlands, explaining why they are rarely recognized.

Conclusion

2020 ◽  
pp. 243-252
Author(s):  
Ted Nannicelli
Keyword(s):  
Moral Psychology ◽  
Applied Ethics ◽  
The Other ◽  
Ethical Criticism ◽  
Artistic Creation ◽  
Fine Grained ◽  
Parallel Path ◽  
Ethical Context ◽  
The One ◽  
Future Work

This chapter summarizes the book’s central claims and looks at paths for future work on the applied ethics of artistic creation and ethical criticism. It suggests the need for two parallel strands of inquiry: On the one hand, as the term “applied ethics” suggests, there is a need for a finer-grained understanding of both the artistic and ethical contexts of artistic creation—an understanding that will need to be informed by research across a number of fields, including anthropology, art history, and moral psychology. On the other hand, whatever details of that context are revealed by this fine-grained analysis, there will be a more abstract conceptual challenge about how to reconcile the norms of that art-historical and ethical context with those in currency in the art-historical and ethical context from which one is judging the work. So, the parallel path of inquiry is in metaethics.

scholarly journals Traceable Attribute-Based Secure Data Sharing with Hidden Policies in Mobile Health Networks

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xueyan Liu ◽  
Yukun Luo ◽  
Xiaotao Yang
Keyword(s):  
Bilinear Pairing ◽  
Health Networks ◽  
Access Policy ◽  
Fine Grained ◽  
Attribute Based Encryption ◽  
Data Owner ◽  
Data User ◽  
Efficient Scheme ◽  
And Performance ◽  
The One

The growing need to store, share, and manage medical and health records has resulted in electronic medical health sharing system (mHealth), which provides intelligent medical treatment for people. Attribute-based encryption (ABE) is regarded as a new cryptology to enhance fine-grained access control over encrypted sharing data in mHealth. However, some existing attribute-based mHealth systems not only violate the one-to-many application characteristics of attribute-based encryption mechanism but also destroy the anonymity of user. In this study, an efficient scheme is proposed to tackle the above defaults and offer two-way anonymity of data owner and data user by introducing a pseudoidentity. The computation of hidden access policy is reduced by removing the bilinear pairing, whereas the interaction between cloud storage and data user is avoided to save bandwidth during trapdoor generation. We also consider the temporal factor of the uploaded information by introducing access validity. Security and performance analyses show that the proposed scheme is efficient without reducing security.

scholarly journals Volcanic Grinding Tools in Ustica Island (Tyrrhenian Sea, Italy): Local Production vs. Import of Morgantina-Type Millstones in the Hellenistic-Roman Period

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 389
Author(s):  
Patrizia Santi ◽  
Franco Foresta Martin ◽  
Francesca Spatafora ◽  
Sandro de Vita ◽  
Alberto Renzulli
Keyword(s):  
Bronze Age ◽  
Mediterranean Area ◽  
Major And Trace Elements ◽  
Alkaline Basalt ◽  
Tyrrhenian Sea ◽  
Local Production ◽  
Middle Bronze Age ◽  
Southern Tyrrhenian Sea ◽  
The Mediterranean ◽  
Geochemical Analyses

This archaeometric study was focused on 28 grey to dark-grey lava artifacts found in Ustica Island (Southern Tyrrhenian Sea, Italy) and referable to different grinding tools: saddle querns, rotary Morgantina-type millstones, rotary hand-mills and one small mortar. Mineralogy, petrography and bulk rock geochemical analyses emphasized that most of the grinding artifacts belonged to the Na-Alkaline series of Ustica, mainly basalts, hawaiites and mugearites. Nevertheless, some millstone samples did not match major and trace elements of Ustica lavas, in particular, one high-TiO2 Na-Alkaline basalt from Pantelleria Island, some tholeiitic/transitional basalts from the Iblei Mountains and one Calcalkaline basaltic andesite, most likely from the Aeolian Archipelago. The Hellenistic–Roman re-colonisation of Ustica Island, after ca. one millennium of nearly complete abandonment, was testified by the import of the non-local Morgantina-type rotary millstones, very widespread in the Mediterranean area from 4th–3rd century BC. This import of millstones represented, for the Ustica inhabitants, a real breakthrough for developing a local production of grinding artifacts on the basis of the new rotary technique which was much more efficient than that of the archaic saddle querns, largely used in the Middle Bronze Age. The results are also discussed in the framework of the overall volcanic millstone trade in the Mediterranean area and the different milling technology in antiquity.

scholarly journals Attribute-Guard: Attribute-Based Flow Access Control Framework in Software-Defined Networking

2020 ◽  
Vol 2020 ◽  
pp. 1-18 ◽  
Author(s):  
Xianwei Zhu ◽  
ChaoWen Chang ◽  
Qin Xi ◽  
ZhiBin Zuo
Keyword(s):  
Access Control ◽  
Software Defined Networking ◽  
Authentication Protocol ◽  
Network Characteristics ◽  
Fine Grained ◽  
Control Framework ◽  
Data Plane ◽  
Data Validity ◽  
The One ◽  
Matching Field

Software-defined networking (SDN) decouples the control plane from the data plane, offering flexible network configuration and management. Because of this architecture, some security features are missing. On the one hand, because the data plane only has the packet forwarding function, it is impossible to effectively authenticate the data validity. On the other hand, OpenFlow can only match based on network characteristics, and it is impossible to achieve fine-grained access control. In this paper, we aim to develop solutions to guarantee the validity of flow in SDN and present Attribute-Guard, a fine-grained access control and authentication scheme for flow in SDN. We design an attribute-based flow authentication protocol to verify the legitimacy of the validity flow. The attribute identifier is used as a matching field to define a forwarding control. The flow matching based on the attribute identifier and the flow authentication protocol jointly implement fine-grained access control. We conduct theoretical analysis and simulation-based evaluation of Attribute-Guard. The results show that Attribute-Guard can efficiently identify and reject fake flow.

Ontology-Based Data Warehousing and Mining Approaches in Petroleum Industries

2011 ◽  
pp. 211-236 ◽  
Author(s):  
Shastri L. Nimmagadda ◽  
Heinz Dreher
Keyword(s):  
Data Structures ◽  
Data Warehousing ◽  
Heterogeneous Data ◽  
Knowledge Mapping ◽  
Financial Decisions ◽  
Fine Grained ◽  
Knowledge Models ◽  
Visualization Of Data ◽  
The One ◽  
Commercial Organizations

Several issues of database organization of petroleum industries have been highlighted. Complex geo-spatial heterogeneous data structures complicate the accessibility and presentation of data in petroleum industries. Objectives of the current research are to integrate the data from different sources and connecting them intelligently. Data warehousing approach supported by ontology, has been described for effective data mining of petroleum data sources. Petroleum ontology framework, narrating the conceptualization of petroleum ontology and methodological architectural views, has been described. Ontology based data warehousing with fine-grained multidimensional data structures, facilitate to mining and visualization of data patterns, trends, and correlations, hidden under massive volumes of data. Data structural designs and implementations deduced, through ontology supportive data warehousing approaches, will enable the researchers in commercial organizations, such as, the one of Western Australian petroleum industries, for knowledge mapping and thus interpret knowledge models for making million dollar financial decisions.

scholarly journals Visual attention is available at a task-relevant location rapidly after a saccade

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Tao Yao ◽  
Madhura Ketkar ◽  
Stefan Treue ◽  
B Suresh Krishna
Keyword(s):  
Eye Movements ◽  
Spatial Attention ◽  
Spatial Location ◽  
Temporal Analysis ◽  
Neuronal Population ◽  
Attentional Modulation ◽  
Attention Task ◽  
Fine Grained ◽  
The One ◽  
Precise Time

Maintaining attention at a task-relevant spatial location while making eye-movements necessitates a rapid, saccade-synchronized shift of attentional modulation from the neuronal population representing the task-relevant location before the saccade to the one representing it after the saccade. Currently, the precise time at which spatial attention becomes fully allocated to the task-relevant location after the saccade remains unclear. Using a fine-grained temporal analysis of human peri-saccadic detection performance in an attention task, we show that spatial attention is fully available at the task-relevant location within 30 milliseconds after the saccade. Subjects tracked the attentional target veridically throughout our task: i.e. they almost never responded to non-target stimuli. Spatial attention and saccadic processing therefore co-ordinate well to ensure that relevant locations are attentionally enhanced soon after the beginning of each eye fixation.

Identifying and determining SPARQL endpoint characteristics

2014 ◽  
Vol 10 (3) ◽  
pp. 226-244 ◽  
Author(s):  
Johannes Lorey
Keyword(s):  
Real World ◽  
Performance Metrics ◽  
Knowledge Bases ◽  
Distributed Query Processing ◽  
Data Repositories ◽  
Content Type ◽  
Fine Grained ◽  
Distributed Query ◽  
Extensive Evaluation ◽  
The One

Purpose – The purpose of this study is to introduce several metrics that enable universal and fine-grained characterization of arbitrary Linked Data repositories. Publicly accessible SPARQL endpoints contain vast amounts of knowledge from a large variety of domains. However, oftentimes these endpoints are not configured to process specific workloads as efficiently as possible. Assisting users in leveraging SPARQL endpoints requires insight into functional and non-functional properties of these knowledge bases. Design/methodology/approach – This study presents comprehensive approaches for deriving these metrics. More specifically, the study utilizes concrete SPARQL queries to determine corresponding values. Furthermore, it validates and discusses the introduced metrics through extensive evaluation on real-world SPARQL endpoints. Findings – The evaluation determined that endpoints exhibit different characteristics. While it comes as no surprise that latency and throughput are influenced by the network infrastructure, the costs for join operations depend on a number of factors that are not obvious to a data consumer. Moreover, as the author discusses mean, median and upper quartile values, it was found both endpoints behaving consistently as well as repositories offering varying levels of performance. Originality/value – On the one hand, the contribution of the authors work lies in assisting data consumers in evaluation of the quality of service of publicly available SPARQL endpoints. On the other hand, the performance metrics introduced in this study can also be considered as additional input features for distributed query processing frameworks. Moreover, the author provides a universal means for discerning characteristics of different SPARQL endpoints without the need of (synthetic or real-world) query workloads.

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