**3. Data trust in the virtual world**

After the 4th industrial revolution, the virtual world has grown rapidly. The real thing has been converted into data from the virtual world, and the virtual world has even played a role in leading the real world. Here, we have a question about the reliability of data about whether the real thing is becoming data accurately in the virtual world. In the virtual world, trust technology is emerging as an important issue. We can think of blockchain as one of these trust technologies.

Blockchain was first proposed in 2008 in Satoshi Nakamoto's paper "Bitcoin: P2P Electronic Money System". Blockchain can be said to be a technology that gives trust in transactions between individuals. A blockchain consists of blocks containing data and a chain that connects them. It is a blockchain to create and connect blocks, and consensus algorithms are used in this process. Any of the nodes participating in the network can create blocks, but not all generated blocks are connected, and only one block is recognized and connected. Since only one block among many blocks is connected to the previous block and the remaining blocks are discarded, consensus among participating nodes to select one block is essential. As a method of reaching consensus, consensus algorithms such as Proof of Work (PoW) and Proof of Stake (PoS) are used. If it is recognized as a unique block by all nodes, the node that created the block will receive cryptocurrency as a reward. This action is called mining, and a blockchain connected only with blocks created by mining is called a Canonical Chain.

Blockchain is developing and evolving as shown in **Table 1** [9]. Blockchain 1.0 was a period of innovation in the financial system with the advent of Bitcoin. Bitcoin is meaningful in that it attempts a single global financial system based on decentralization and decentralization, which are the core values of blockchain.

#### **Table 1.**

*Blockchain paradigm evolution direction.*

Blockchain 2.0 is a period of contract automation centered on Ethereum smart contracts. It made it possible to execute contracts with legal effect online only with computer code without a transaction intermediary. It is a period that showed the potential for development as an online trading platform. Blockchain 3.0 is the stage in which blockchain technology is spread and applied to various industries. In order to solve the problems of the previous blockchain, technological improvements such as changes in consensus algorithms, improvement of transaction processing speed, and in-house decision-making functions are being made [10]. While it is expected that artificial intelligence will be applied to more expanded fields in Blockchain 3.0, more various applications of blockchain and artificial intelligence are expected to appear in the Metaverse environment.

### **4. Blockchain-based Metaverse**

#### **4.1 Ethereum code**

Ethereum is a platform network designed to operate various decentralized applications (DApps), based on its own blockchain. Just as the basic framework and details of Internet standards were documented as RFCs, Ethereum Request for Comment (ERC) documents the details of Ethereum. In DApps using the Ethereum network, the basic protocol for issuing tokens is expressed as ERC-number as shown in **Table 2**. ERC-number is a protocol to follow when issuing tokens from DApps using the Ethereum network. Ethereum standard documents start with ERC-20, ERC-165, ERC-223, ERC-621, ERC-721, ERC-777, ERC-827, ERC-884, ERC-998, ERC-1155, ERC-1404 etc. [11].

Among them, ERC-20 is a protocol related to replaceable tokens, and ERC-20 tokens have the same value and function and can be exchanged with each other. The Ethereum project is issuing tokens based on ERC-20 and allowing investment and various businesses to take place.

ERC-721 is a protocol for NFT (Non-Fungible Tokens). NFT guarantees uniqueness by keeping encrypted transaction history permanently on the blockchain. Each token has a unique recognition value, authenticating the ownership of digital assets and assigning a value to the transaction. NFT has been mainly used to commemorate special moments or to collect digital assets, and recently it is creating a new digital content business by combining it with Metaverse.

**Table 2.** *ERC(Ethereum request for comment)-number.*


*Edited by Yves Rybarczyk*

Rehabilitation enables people with sensorimotor and cognitive disabilities to regain functions and autonomy. However, over the past few years, there has been a reduction in healthcare providers to assist patients. Fortunately, this decline has been accompanied by an increase in technological applications to support health systems. This new paradigm brings promising perspectives but raises questions regarding the therapy assisted by computers. To address these issues, this book intends to clarify the multidisciplinary aspects of medical engineering. The volume covers studies on the technical challenges in and barriers to the development of efficient rehabilitation and assistive technologies. It also provides a comprehensive approach to the recent advances in tele-health as a complementary medium to support the recovery process and to enhance patients' empowerment.

ISBN 978-1-78923-883-9

Assistive and Rehabilitation Engineering

Published in London, UK © 2019 IntechOpen © 858667192 / iStock


**6. Discussion and Perspectives**

In the study, we have defined instruments by using central subspaces of the dual of a C∗-algebra. We have checked its consistency with the definition in the von Neumann algebraic setting. This result means that the extension of the measurement theory to C∗-algebra in the paper is valid. Furthermore, we have proposed a unification of the measurement theory and the sector theory: we have defined and characterized the centrality of instruments. In addition, we have discussed the operational characterization and macroscopic nature of quantum measurement. In the context, we have actively used the disjointness of states to distinguish different output values of the meter. Our results are, of course, applicable to systems described by C\*-algebras generated from field operators, and the macroscopic aspects of quantum fields can now be discussed in terms of measurement theory.

In the setting of AQFT, we use a local net {A(O)}O∈R1 on a space *M*1 in order to describe the DP phenomena. In describing the measurement of DPs, only the use of the local net first adopted is not enough. In fact, to detect (the effect of) DPs, we need an operation wherein some probe is brought closer to the spatial scale at which DPs are generated. We introduced an extension of a local net to mathematically describe the operation at the level of observable algebras.

**Definition 12.** *Let* {A(O)}O∈R1 *and* {B(O)}O∈R2 *be local nets on M*1 *and M*2*, respectively.* {B(O)}O∈R2 *is an extension of* {A(O)}O∈R1 *if it satisfies the following three conditions:* (*i*) *M*1 ⊂ *M*2*.* (*ii*) R1 ⊂ R2*.* (*iii*)*Forevery*O∈R1*,*A(O)⊂B(O)*.*

We use the extensions of a local net because the construction of the composite system of the system of interest and a measuring apparatus is not so simple. In particular, the construction of the composite system by the tensor product is not always applicable to quantum fields.

Let {B(O)}O∈R2 be a local net on *M*2 and an extension of a local net {A(O)}O∈R1 on *M*1. We suppose that *M*1 is bounded. The composite system of the original system and a probe, which is close to the original system on the spatial scale where DPs are generated, is described by {B(O)}O∈R2 as a quantum field. Furthermore, the material system, which is a part of the composite system, is assumed to be localized in the neighborhood of *M*1. In the composite system, the generation and annihilation of DPs constantly occur near non-uniform materials in the unstable situation where light continues to incident constantly. By measuring the emitted light at regions far from *M*1, we check (or estimate) the effect of DPs generated in *M*1.

Constructing a concrete model of DPs as a quantum field in order to correlate experiments of DPs with the theory is a future task. We hope to describe the DP phenomena as open systems at the next stage. In the future, clarification of the relationship between this study and the recent trends in DP research [33] is required. Moreover, the mathematical theory of quantum measurement for quantum systems described by C∗-algebras should be further developed.

**Funding:** This research received no external funding.

**Acknowledgments:** The author thanks anonymous reviewers for their comments to improve the quality of this paper.

**Conflicts of Interest:** The author declares no conflict of interest.


*3.2. Bid Preparation and Energy Deviations*

The participation of VRE producers in balancing markets involves the preparation and submission of bids, typically for a period of one hour, creating large difficulties for producers to keep a stable and efficient operation without curtailments or deviations. Specifically, WPPs need to bid their expected active power, *Pbid*(*T*), in day-ahead and intra-day markets, based on forecasts that use time horizons between 18 h and 42 h (for DAMs), and between 2 h and 7 h (for intra-day markets), ahead of real-time operation. At real-time, considering the data obtained from wind parks, there is the possibility to compute the average production, *Pavg*(*T*), for a particular period of time *T*.

From the point of view of the grid, WPPs produce instantaneous power, *p*(*t*), based on the wind speed, the characteristics and power of wind turbines and the configuration of wind parks. The energy, *E*(*T*), produced during a period of time *T*, is computed as follows:

$$E(T) = \int\_0^T p(t)dt = T \times P\_{\text{avg}}.\tag{1}$$

The deviation, *Edev*(*T*), in period *T* is given by the following formula:

$$E\_{d\sigma\eta}(T) = T \times P\_{\text{avg}} - T \times P\_{\text{bind}} = T(P\_{\text{avg}} - P\_{\text{bind}}) \,. \tag{2}$$

Figure 1 illustrates the relation between these variables for a particular hour of operation (*T* = 1). It shows the traded/scheduled power, *Pbid*(*T*), of a particular wind power producer in the day-ahead market (red curve). The corresponding energy, *Ebid*(*T*), is represented by the orange area. The real production of the wind power producer is given by *p*(*t*) (solid blue curve). The difference between the instantaneous power and the scheduled power gives the energy deviation, *Edev*(*T*), which is represented by the light blue area.

**Figure 1.** Bids of wind power producers and the associated deviations.

Considering now that wind power producers are allowed to make only single bids in the balancing market (i.e., bids without considering aggregation of WPPs), the maximum expected power that they can submit, *PBMbid*(*T*), is defined by the difference between the minimum instantaneous deviation and the traded power:

$$P\_{BMbid}(T) = (-1)^{\varepsilon} \times \left( \min\left( |p(t)| \right) - P\_{bid}(T) \right) \tag{3}$$

where *t* = 1, ... , 60, and the bid is of the type upward regulation, i.e., *c* = 0 (for a downward regulation bid, consider the maximum instead of the minimum, and *c* = 1).

Figure 1 shows that the submission of *PBMbid*(*T*) to the balancing market, and its subsequent acceptance by the system operator, results in a waste of energy (the difference between the dashed and solid blue curves). For the particular case of the secondary reserve market, the waste of energy may be even larger than that. Accordingly, existing products associated with the balancing market may not be considered adequate to deal with the variability and uncertainty of VRE. A possible solution to overcome the problem is to consider aggregated bids involving VRE producers and conventional generation. However, not all power systems allow aggregated bids, specially for the case of BMs.


*Adherence of* Candida albicans *on Polymethyl Methacrylate in Probiotics Solution DOI: http://dx.doi.org/10.5772/intechopen.112321*

substances secreted by tissue which have the ability to stimulate microbial growth. Parker first used the term probiotic in relation to its modern usage, defining it as "organisms and substances that contribute to intestinal microbial balance." Later, Fuller amended this definition by emphasizing the important role of probiotics in establishing the balance of intestinal microbial. This reformed definition emphasizes on the requirement of viability for probiotics and introduces the aspect of a beneficial effect on the host. Havenaar et al. expanded the definition further to include mono or mixed cultures of microorganisms applied to animals or humans that improve the properties of the indigenous microflora. Salminen and Schaafsma further broadened the definition of probiotics to include dairy products such as fermented cereals, sauerkraut, and salami that contain viable probiotic microorganisms. This definition showed that probiotics benefit, effect health and nutrition of the host. Salminen and Schaafsma broadened the definition of probiotics even further by no longer limiting the proposed health effects to influences on the indigenous microflora.

According to today's definition, probiotics are called "healthy bacteria" with many health benefits such as preventing intestinal infections, improving immunity, lactose intolerance and intestinal microbial balance, and anti-hypercholesterolemia and antihypertensive effect, and reduces traveler's diarrhea. Recent research has also focused on their use in the treatment of skin and mouth diseases [2].

### **2.2 Probiotics and oral cavity**

Because oral cavity is the first section of the gastrointestinal tract, it is logical to think that some probiotics may affect the oral microbiota. The most commonly used probiotic bacterial strains are the *genera Lactobacillus* and *Bifidobacterium*. Specific *lactobacilli* species are yet to be identified as exclusively in oral microbiota, although some common ones include *L. paracasei, L. plantarum, L. rhamnosus, and L. salivarius. Bifidobacteria* is among the first anaerobic bacteria to colonize in the oral cavity, and possible species isolated from oral samples are *B. bifidum, B. dentium, and B. longum*. Culture-based studies confirm that *bifidobacteria* is among the first anaerobes in the oral cavity. Indeed, both *lactobacilli* and *bifidobacteria* can be found in breast milk, suggesting early exposure of the oral cavity to these bacteria [4].

### **2.3 Potential mechanisms of probiotic effects in the oral cavity**

Probiotics can improve oral health through three main mechanisms: normalization of oral microbiota, modulation of the immune response, and metabolic effects. By inhibiting harmful bacteria and promoting beneficial bacteria, probiotics can help restore balance in the mouth and reduce the risk of gum disease and tooth decay. Probiotics can also modulate the immune response and prevent inflammation, particularly in individuals with compromised immune systems. Lastly, probiotics can have metabolic effects that improve overall oral health by breaking down food particles and preventing the buildup of plaque and tartar. In summary, the potential mechanisms of probiotic action in the oral cavity resemble those in the intestine and can benefit oral health significantly [5].


**4. Life Practices**

In the face of crisis, practices are critical, intertwined with the practical wisdom that shapes and is reshaped by practice. The significance of practice is clear in Rachel Carson's close observation of sea creatures, and Robin Wall Kimmerer's existential and scientific engagement with wild strawberries and pecan trees, and her study of the Potawatomi language. Here I identify four practices that are important to reshaping and deepening practical wisdom for ecological justice: attending, searching, imagining, and communal living and acting. To ground the proposals, I draw especially on the wisdom of activist scholars and scholar activists.


*Editorial* **Ecology of Predation and Scavenging and the Interface: A Special Issue**

**Marcos Moleón**

Department of Zoology, University of Granada, 18071 Granada, Spain<EMAIL_ADDRESS>or<EMAIL_ADDRESS>
Predation and scavenging are pervasive ecological interactions in both terrestrial and aquatic environments. The ecology, evolution and conservation of scavengers, and especially predators, have received wide scientific attention and public awareness. However, the close connection that exists between predation and scavenging has not been made explicit until recently [1–3]. The propensity to hunt or scavenge a prey may vary within individuals, among different individuals within a population, and among different populations and species, depending on an intricate array of both intrinsic (e.g., morphology, body condition) and extrinsic (e.g., availability of alternative food sources) factors. In turn, the recognition that carnivorous animals may obtain meat by either hunting prey or scavenging their carcasses has profound implications, from individual morphology, physiology, and behavior to population, community, and ecosystem structure and functioning [1–5].

Given the novelty of this integrative research topic, many relevant questions have yet to be resolved. This Special Issue, through the three research papers and the three reviews that comprise it, aims to deal with some of these questions from diverse perspectives and methodological approaches.

In the first paper of this SI, Ordiz et al. [6] describe, in detail, the predatory and scavenging behavior of wolves (*Canis lupus*) and bears (*Ursus arctos*) in a Swedish area to understand the intrinsic and extrinsic conditions that favor the coexistence of these competing top carnivores. They show that bears and wolves were connected by frequent indirect interactions, mainly through bear scavenging of wolf kills. Scavenging by bears diminished in the moose calving season, when both carnivores turned to the abundant and vulnerable calves as the main food source. Additionally, not all bears were equally prone to scavenging wolf kills, as these carcasses were avoided by females with cubs of the year, i.e., the bear population sector that is more vulnerable to predation.

Teurlings et al. [7] explore a major anti-scavenger strategy of the other top carnivore, the Eurasian lynx (*Lynx lynx*). To prevent scavenger access to the remains of large prey, and thus to secure subsequent meals, lynxes and other felids usually hide their kills by covering them with different materials, such as vegetation and snow. This study, conducted in an area of southeastern Norway, shows that this caching behavior is an efficient anti-scavenger strategy, as cached prey (namely, roe deer, *Capreolus capreolus*) were discovered later than non-cached prey by both vertebrate (especially, birds) and invertebrate scavengers. These results are crucial to fully explain the functional responses of lynxes to their prey, and lynx–prey dynamics in general.

In the next empirical study, Teurlings et al. [8] further focus on the Eurasian lynx–roe deer system to investigate whether above-ground ecological processes linked to predation can trigger cascading effects on below-ground processes via carrion supply and decomposition. Unlike similar studies conducted in other systems, Teurlings et al. did not detect any effect of carcass remains on key chemical parameters of soil and vegetation about two years after death. These findings could be explained by the relatively small size of roe dear carcasses and by their efficient consumption by lynxes and scavengers.

The first review of this SI, made by Luna et al. [9], compares the scientific effort that has been devoted to date to predation and scavenging processes in urban habitats, which

**Citation:** Moleón, M. Ecology of Predation and Scavenging and the Interface: A Special Issue. *Diversity* **2021**, *13*, 95. https://doi.org/ 10.3390/d13020095

Received: 18 February 2021 Accepted: 19 February 2021 Published: 22 February 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

are increasingly represented in the planet Earth. The authors found that predation has been far more studied than scavenging. Moreover, urban ecologists became interested in scavenging several decades later than predation. The study species and areas of articles on scavenging were a subset of the species and areas studied in articles on predation. Luna et al. conclude that proper recognition of both the predatory and scavenging facets of carnivores will be needed to fully understand their role in urban food webs and their ecological consequences for urban environments.

A key question in predation–scavenging research is to identify the adaptations that make a species successful in exploiting a given niche within the predation–scavenging gradient. In this line, Potier [10] reviews the visual specializations associated with predatory and scavenging diurnal raptors. He finds that the eye size relative to body mass, as well as binocularity (as opposed to an enlarged field of view), increases towards the predation extreme of the gradient. He also identifies a qualitative anatomical difference between typical predators and more opportunistic and scavenger species, with the former having a second, temporally positioned fovea (probably used during prey capture) in addition to the central fovea that occurs in all species. These findings highlight the close relationship between visual system specializations and foraging ecology, which was often unrelated to phylogeny.

In the last contribution to this SI, Moleón and Sánchez-Zapata [11] reveal the important, though largely overlooked, role that carrion plays in the landscapes of fear and disgust. By reviewing the scientific literature, they identify the main ways in which carrion may be scary and disgusting, namely the principal interaction pathways between carcasses and their visitors (both carnivore and herbivore species) that expose the former to predators (see Ordiz et al. [6] for an empirical example in this SI) and parasites at carcass sites. In addition, they identify major knowledge gaps, which are mostly related to the disgusting facet of carrion. The presented conceptual framework may help to understand animal behavior and ecological processes, including cascading effects, around carrion resources.

The papers and reviews of this SI are proof of the explicit interest in the relationship between predation and scavenging that has currently pervaded many research groups worldwide. Nevertheless, as evidenced by this SI, important knowledge gaps still arise. For instance, investigations into marine, freshwater, and tropical terrestrial environments, as well as on invertebrates, would be especially welcome. I hope this SI may contribute to inspire future research ideas and effort on this general topic. Overall, the growing body of scientific knowledge on the interface between predation and scavenging will definitely dismiss the traditional view that they are disconnected ecological processes.

**Funding:** The author was supported by a research contract Ramón y Cajal from the Spanish Ministry of Economy and Competitiveness (RYC-2015-19231) and by a project from the Spanish Ministry of Economy, Industry and Competitiveness and EU ERDF funds (CGL2017-89905-R).

**Acknowledgments:** I would like to thank all the authors for their remarkable contribution to this SI. I also wish to thank the staff members at the MDPI editorial office for their dedicated support.

**Conflicts of Interest:** The author declares no conflict of interest.

#### **References**


**CURRENT TOPICS IN ANESTHESIOLOGY**

Edited by **Riza Hakan Erbay**

#### **Current Topics in Anesthesiology**

http://dx.doi.org/10.5772/63140 Edited by Riza Hakan Erbay

#### **Contributors**

Zeki Tuncel Tekgül, Burcu Özalp Horsanalı, Mustafa Ozan Horsanali, Jesse Musokota Mumba, Freddy Kasandji Kabambi, Christian Tshebeletso Ngaka, Ayse Belin Ozer, Sibel Ozcan, Takashi Kawano, Fabricio Locatelli, İsmail Demirel, Esef Bolat, Aysun Yıldız Altun, Yusuke Asakura, Maho Kinoshita, Yusuke Kasuya, Makoto Ozaki, Yuta Matsunaga, Masahiko Tsuchiya

#### **© The Editor(s) and the Author(s) 2017**

The moral rights of the and the author(s) have been asserted.

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#### **Notice**

Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book.

First published in Croatia, 2017 by INTECH d.o.o. eBook (PDF) Published by IN TECH d.o.o. Place and year of publication of eBook (PDF): Rijeka, 2019. IntechOpen is the global imprint of IN TECH d.o.o. Printed in Croatia

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