Elusive Problems Research Articles

Evaluating the light environment as a contributor to colour differences among related bird species

Abstract Understanding the diversity of colour in nature has been one of the more elusive evolutionary problems. In the terrestrial environment, comparative analyses have associated differences in colour between species to light environment, background, and receiver perception. However, these account for only a small fraction of colour diversity, and it has been difficult to explain why a certain species is the colour it is. Here we examine colour variation across 12 very similar species of warblers belonging to the genus Phylloscopus, whose general brightness along an achromatic axis has previously been related to light intensity in their habitat. Many of these species also show variation in the colour of several plumage regions, including the wing bar, belly, and white vs. green in the outer tail feathers. We ask if these differences can be connected to the spectrum of light found in the habitat of each species. We find little evidence that contrast between patches and adjacent plumage or colour per se is affected by light environment. We argue that the heterogeneity of light environments experienced within a habitat and throughout the day make it unlikely that downwelling irradiance alone has a direct influence on colour variation. Accordingly, other features must have driven colour evolution. Diversification may be driven by environmental characteristics, such as background, or unrelated to environment altogether, reflecting the possibility that many different variants may effectively stimulate a receiver, and those that appear in a certain species reflect stochastic processes (e.g. mutation) and contingency (form of the ancestor).

Towards identifying the characteristics of youth with severe and enduring mental health problems in practice: a qualitative study

A group of youth with severe and enduring mental health problems (SEMHP) falls between the cracks of the child-and-adolescent psychiatry (CAP) system. An insufficient understanding of these youth’s mental health problems results in a failure to accurately identify and provide support to these youth. To gain a deeper understanding, the aim of this study is to explore characteristics of youth with SEMHP in clinical practice based on the experiences of youth and clinicians in CAP. This qualitative study consisted of 20 semi-structured interviews with 10 youth with lived experience and 10 specialized clinicians in CAP. Both a thematic and content analysis was conducted to identify, assess, and report themes associated with youth with SEMHP. Themes were individual characteristics such as trauma, masking, self-destructive behavior, interpersonal distrust as well as environmental and systematic characteristics including parental stressors, social isolation and societal stressors, which go beyond the existing classifications. These characteristics profoundly impact youth’s daily functioning across various life domains, creating an interactive process, ultimately leading to elusive mental health problems and overwhelming feelings of hopelessness. The authors recommend proper assessment of characteristics in all life domains affected and their perpetuating effect on SEMHP during diagnostics in CAP. Engaging in a dialogue with youth themselves is crucial due to the nature of youth’s characteristics, which frequently transcend traditional classifications and may not be immediately discernible. It also requires an integrated care approach, entailing collaborations between educational institutions and mental healthcare providers, and attention to potential indicators of deficits in the healthcare system and society.

Resilient Hospital Design: From Crimea War to COVID-19.

Serious COVID-19 nosocomial infection has demonstrated a need to design our health services in a different manner. Triggered by the current crisis and the interest in rapid deployable hospital, this article discusses how hospital building layouts can be improved to streamline the patient pathways and thus to reduce the risk of hospital-related infections. Another objective of this work is to explore the possibility to develop flexible and scalable hospital building layouts through modular construction. This enables hospitals to better cope with different future demands and thereby enhance the resilience of the healthcare facilities. During the first wave of COVID-19, approximate one-seventh to one-fifth COVID-19 patients and majority of infected healthcare workers acquired the disease in NHS hospitals. Similar issues emerged during the Crimean War (1853-1856) when more soldiers died from infectious diseases rather than of battlefield casualties in Scutari Hospital. This led to an important collaborative work between Florence Nightingale, who looked into this problem statistically, and Isambard Kingdom Brunel, who designed the rapid deployment Renkioi Hospital which yielded a death rate 90% lower than that in Scutari Hospital. While contemporary medical research and practice have moved beyond Nightingale's concept of contagion, challenges of optimizing hospital building layouts to support healing and effectively combat nosocomial infections still pose elusive problems that require further investigation. Through case study investigations, this article evaluates the risk of nosocomial infections of airborne transmissions under different building layouts, and this provides essential data for infection control in the new-build or refurbished healthcare projects. Improved hospital layout can be achieved through reconfiguration of rooms and concourse. Design interventions through evidence-based infection risk analysis can reduce congestion and provide extra separation and compartmentalization which will contribute the reduced nosocomial infection rate. A resilient hospital shall be able to cope with unexpected circumstances and be flexible to change when new challenges arise, without compromising the safety and well-being of frontline medical staff and other patients. Such an organizational resilience depends on not only flexible clinical protocols but also flexible hospital building layouts. The latter allows hospitals to get better prepared for rapidly changing patient expectations, medical advances, and extreme weather events. The reconfigurability of an existing healthcare facility can be further enhanced through modular construction, standardization of building components, and additional space considered.

Towards causal mechanisms of consciousness through focused transcranial brain stimulation.

Conscious experience represents one of the most elusive problems of empirical science, namely neuroscience. The main objective of empirical studies of consciousness has been to describe the minimal sets of neural events necessary for a specific neuronal state to become consciously experienced. The current state of the art still does not meet this objective but rather consists of highly speculative theories based on correlates of consciousness and an ever-growing list of knowledge gaps. The current state of the art is defined by the limitations of past stimulation techniques and the emphasis on the observational approach. However, looking at the current stimulation technologies that are becoming more accurate, it is time to consider an alternative approach to studying consciousness, which builds on the methodology of causal explanations via causal alterations. The aim of this methodology is to move beyond the correlates of consciousness and focus directly on the mechanisms of consciousness with the help of the currently focused brain stimulation techniques, such as geodesic transcranial electric neuromodulation. This approach not only overcomes the limitations of the correlational methodology but will also become another firm step in the following science of consciousness.

Aflatoxin biocontrol in practice requires a multidisciplinary, long-term approach

One of the most elusive food safety problems is the contamination of staple crops with the highly carcinogenic aflatoxins produced byAspergillussection Flavi fungi. Governments, farmers, institutions, consumers, and companies demand aflatoxin solutions. Many aflatoxin management technologies exist, but their real-life use and effectiveness is determined by diverse factors. Biocontrol products based on atoxigenic isolates ofA. flavuscan effectively reduce aflatoxins from field to fork. However, development, testing, and registration of this technology is a laborious process. Further, several barriers prevent the sustainable use of biocontrol products. There are challenges to have the products accepted, to make them available at scale and develop mechanisms for farmers to buy them, to have the products correctly used, to demonstrate their value, and to link farmers to buyers of aflatoxin-safe crops. Developing an effective aflatoxin management technology is the first, major step. The second one, perhaps more complicated and unfortunately seldomly discussed, is to develop mechanisms to have it used at scale, sustainably, and converged with other complementary technologies. Here, challenges and actions to scale the aflatoxin biocontrol technology in several countries in sub-Saharan Africa are described with a view to facilitating aflatoxin management efforts in Africa and beyond.

Remarks on the inconsistency measure of the Analytic Hierarchy Process

The Analytic Hierarchy Process (AHP) is a popular Multi-Criteria Decision Making (MCDM) method. The workability of AHP made it suitable for solving complicated and elusive decision problems that subsequently led to its widespread applications in highly diverse fields. However, AHP has also received criticisms on various fronts, one of which is the rank reversal problem. When a replica of an existing alternative is introduced in the Multi-Criteria Decision (MCD) setting, it sometimes causes rank order reversal among alternatives. However, the addition of a replica of an alternative in the MCD setting is not limited to the rank reversal problem, but it also affects the inconsistency measure computed for the decision-maker (DM). An empirical study was conducted using AHP to measure the changes in the inconsistency of the DM on a well-defined and familiar MCD problem. The results indicate that when a replica is added to a pair-wise comparison matrix, the inconsistency of the DM reduces. It is found that there are two sources of inconstancy in a pair-wise preference matrix. One is intransitivity and another is the limitation of the 1–9 ratio scale. It is found that an inconsistency up to 50% is purely because of limitations of the ratio scale and higher inconsistencies are purely because of intransitivity in preferences defined by the DM. Therefore, the DMs should review and revise their preferences when their inconsistency exceeds 50%. This 50% threshold is also useful in deciding whether to apply a prediction algorithm to identify near consistent matrices. If the inconsistency of a matrix is above 50%, the prediction algorithms used to improve the consistency cannot be applied on the original inconsistent matrix because the source of inconsistency is intransitivity which means that the DM either does not have complete information about the problem or has not attended to the problem carefully.

Current Challenges and Opportunities Toward Understanding Hydrogen Embrittlement Mechanisms in Advanced High-Strength Steels: A Review

Hydrogen embrittlement (HE) is one of the most dangerous yet most elusive embrittlement problems in metallic materials. Advanced high-strength steels (AHSS) are particularly prone to HE, as evidenced by the serious degradation of their load-bearing capacity with the presence of typically only a few parts-per-million H. This strongly impedes their further development and application and could set an abrupt halt for the weight reduction strategies pursued globally in the automotive industry. It is thus important to understand the HE mechanisms in this material class, in order to develop effective H-resistant strategies. Here, we review the related research in this field, with the purpose to highlight the recent progress, and more importantly, the current challenges toward understanding the fundamental HE mechanisms in modern AHSS. The review starts with a brief introduction of current HE models, followed by an overview of the state-of-the-art micromechanical testing techniques dedicated for HE study. Finally, the reported HE phenomena in different types of AHSS are critically reviewed. Focuses are particularly placed on two representative multiphase steels, i.e., ferrite–martensite dual-phase steels and ferrite–austenite medium-Mn steels, with the aim to highlight the multiple dimensions of complexity of HE mechanisms in complex AHSS. Based on this, open scientific questions and the critical challenges in this field are discussed to guide future research efforts.

Coherence-based characterization of macroscopic quantumness

One of the most elusive problems in quantum mechanics is the transition between classical and quantum physics. This problem can be traced back to the Schr\"{o}dinger's cat. A key element that lies at the center of this problem is the lack of a clear understanding and characterization of macroscopic quantum states. Our understanding of Macroscopic Quantumness relies on states such as the Greenberger-Horne-Zeilinger(GHZ) or the NOON state. Here we take a first principle approach to this problem. We start from coherence as the key quantity that captures the notion of quantumness and demand the quantumness to be collective and macroscopic. To this end, we introduce macroscopic coherence which is the coherence between macroscopically distinct quantum states. We construct a measure that quantifies how global and collective the coherence of the state is. Our work also provides a first-principle way to derive well-established states like the GHZ and the NOON state as the states that maximize our measure. This new approach paves the way towards a better understanding of the Quantum-to-Classical transition.

Catechol-thiol-based dental adhesive inspired by underwater mussel adhesion

The critical problem associated with the underwater mussel adhesive catechol-based 3,4-dihydroxy-L-phenylalanine (DOPA) is its sensitivity to oxidation. To overcome this problem, mussels underwent etching in the presence of acidic pH conditions (<3.0), and thiol chemistry was used to control the propensity of DOPA for oxidation. Similar strategies deployed by mussels are also actively utilized in dental adhesives which undergo etching in the presence of phosphoric acid derivatives to maximize the bonding strength and adapt thiol chemistries to minimize shrinkage stress. In view of the similarities between dental and underwater mussel adhesives, we employ in this study the strategy of mussel adhesion—the combination of DOPA and thiol chemistry with acid etching—to one of the most critical issues in dental adhesives, namely, the dentin bonding with zirconia. As a result, the adhesion bonding between zirconia and dentin, one of the most elusive problems in dentistry, has improved compared to the commercially available adhesive resin formulation. In addition, in view of the similar human oral and mussel adhesive environments, our findings will considerably contribute to the translation of the adhesive system inspired by mussels. Statement of significanceMussels are effectively operated by creating an acidic environment when adhering with 3,4-dihydroxy-l-phenylalanine (DOPA)–thiol redox chemistry for underwater bonding. Similarly, in dental adhesives, phosphoric acid-based etching is used for dentin-bonding materials. In view of the similarity between dental adhesives and underwater mussel adhesives, the combination of DOPA and thiol chemistry with acid etching can be used to overcome one of the most critical issues in dentin medical adhesives. The proposed adhesion method produces high adhesion strengths compared to those currently used in dentin and zirconia adhesives. Here, we extend and evaluate dentin and zirconia dental adhesives by mixing with mussel (DOPA)–thiol redox chemistry and acid etching.

Finite energy Lyapunov function candidate for fractional order general nonlinear systems

The construction of Lyapunov function candidates and the norm of infinite energy solutions remain among the most elusive unsolved problems of fractional order systems. This paper develops a new framework to construct finite energy Lyapunov function candidates for fractional order general nonlinear systems with randomness, uncertainty, time-delay or memory. Fundamentals of fractional order system and equilibrium are revisited to start up the investigation, where the pseudo and true states of fractional order systems are considered. The process of constructing fractional order Lyapunov function candidate is mainly divided into three steps: Firstly, converting the original system into an equivalent Volterra integro-differential equation, where the weak singularity of fractional order system is included. Secondly, the fractional order Lyapunov function candidate is derived by canceling out the weak singularity that acts as the catalyst, and is absorbed into the fractional finite energy terms. Lastly, the first order derivative of the proposed Lyapunov function candidate is negative definite and bounded by power-law relevant terms. From finite energy aspect, the proposed fractional order Lyapunov function candidate is composed of potential, kinetic and/or Riesz potential energies in terms of physics. The fractional order Lyapunov’s theorem and asymptotic stability of equilibrium points are discussed, and some non-Lp stable cases have been shown as fractional order finite energy ones. The impacts of fractional order, region of attraction and initialization state on the stability of equilibrium points are presented as well. Some classical integer order and fractional order results can be deduced from this work. A number of examples are illustrated to substantiate the effectiveness of the proposed unified framework.

Transmissible cancer and the evolution of sex.

The origin and subsequent maintenance of sex and recombination are among the most elusive and controversial problems in evolutionary biology. Here, we propose a novel hypothesis, suggesting that sexual reproduction not only evolved to reduce the negative effects of the accumulation of deleterious mutations and processes associated with pathogen and/or parasite resistance but also to prevent invasion by transmissible selfish neoplastic cheater cells, henceforth referred to as transmissible cancer cells. Sexual reproduction permits systematic change of the multicellular organism’s genotype and hence an enhanced detection of transmissible cancer cells by immune system. Given the omnipresence of oncogenic processes in multicellular organisms, together with the fact that transmissible cancer cells can have dramatic effects on their host fitness, our scenario suggests that the benefits of sex and concomitant recombination will be large and permanent, explaining why sexual reproduction is, despite its costs, the dominant mode of reproduction among eukaryotes.

Unacceptable failure rate of a ceramic-coated posterior cruciate-substituting total knee arthroplasty.

BackgroundAseptic loosening is one of the most elusive problems in total knee arthroplasty. We compared the failure rates of posterior cruciate-substituting total knee arthroplasty utilizing implants with hardened surface coating to a previous cohort of patients who underwent the procedure with traditional cruciate-retaining noncoated cobalt-chrome implants.MethodsA retrospective study was conducted of 1099 total knee arthroplasties performed from 2009 to 2017. Two hundred forty-nine total knee arthroplasties performed from January 2015 to March 2017 under a single design were reviewed retrospectively and compared to the author’s previous 850 total knee arthroplasties performed from January 2009 to December 2014 under a different design.ResultsThis series demonstrated an alarming debonding of cement in the tibial implant. The resultant failure rate of 6% (P < .001) is higher than observed in 850 total knee arthroplasties in the previous 5 years and higher than those reported in the literature giving cause for concern regarding this implant.ConclusionsDue to the observed excessive failure rate, the authors recommend exercising high levels of caution using this implant with hardened surface treatment until further testing can be ascertained as to the root cause of failure.

Expert System for Simulation of Pest and Disease Diagnosis in Onion Plant Using Putty Shafer Method and Rule-Based Approach

The expert system is trying to adopt a system of human knowledge into a computer so that the computer can solve problems like the experts. The expert system is well designed in order to solve a particular problem by mimicking the work of the expert. The development of an expert system is expected to be resolved problems with the help of experts. The problems addressed by an expert not only the problems that rely on algorithms but sometimes elusive problems. An expert with knowledge and experience can overcome these problems. The application of an expert system in this study is made to diagnose pests and diseases in onion plants based on the web. The Data Collection method used is literature studies, interviews and observation. The stages of research used are literature review, data processing analyst, and Onion analyzed and photographed which then is uploaded and analyzed, Dempster Shafer method, application development, evaluation. In the last stage is the pilot study conducted using a Blackbox method and testing to the user. The result of the research is in the form of an expert system application that can diagnose pests and diseases of onion as many as 7 types of diseases. The output system is in the form of onion disease searching result obtained based on the symptoms inputted by the user. The result of Blackbox Testing is all functions of the application successfully run well. Testing to the users rated well both appearance and information of the application.

Fe isotope composition of bulk chondrules from Murchison (CM2): Constraints for parent body alteration, nebula processes and chondrule-matrix complementarity

Chondrules are a major constituent of primitive meteorites. The formation of chondrules is one of the most elusive problems in cosmochemistry. We use Fe isotope compositions of chondrules and bulk chondrites to constrain the conditions of chondrule formation. Iron isotope compositions of bulk chondrules are so far only known from few studies on CV and some ordinary chondrites. We studied 37 chondrules from the CM chondrite Murchison. This is particularly challenging, as CM chondrites contain the smallest chondrules of all chondrite groups, except for CH chondrites. Bulk chondrules have δ56Fe between −0.62 and +0.24‰ relative to the IRMM-014 standard. Bulk Murchison has as all chondrites a δ56Fe of 0.00‰ within error. The δ56Fe distribution of the Murchison chondrule population is continuous and close to normal. The width of the δ56Fe distribution is narrower than that of the Allende chondrule population. Opaque modal abundances in Murchison chondrules is in about 67% of the chondrules close to 0 vol.%, and in 33% typically up to 6.5 vol.%. Chondrule Al/Mg and Fe/Mg ratios are sub-chondritic, while bulk Murchison has chondritic ratios. We suggest that the variable bulk chondrule Fe isotope compositions were established during evaporation and recondensation prior to accretion in the Murchison parent body. This range in isotope composition was likely reduced during aqueous alteration on the parent body. Murchison has a chondritic Fe isotope composition and a number of chondritic element ratios. Chondrules, however, have variable Fe isotope compositions and chondrules and matrix have complementary Al/Mg and Fe/Mg ratios. In combination, this supports the idea that chondrules and matrix formed from a single reservoir and were then accreted in the parent body. The formation in a single region also explains the compositional distribution of the chondrule population in Murchison.

Research and application of local perceptron neural network in highway rectifier for time series forecasting

Time series forecasting is one of the most effective ways to settle the elusive problems of increased penetration of energy industry and financial field. In recent years, neural networks are utilized in time series forecasting owing to the rationality and practicability. However, neural networks always overrate the performance of training data, which results in underestimating the test error. In this work, four important training tactics are proposed for the training and modeling of the networks, and the proposed model has a better forecasting result and a better extrapolation performance. The numerical simulation shows that the proposed methods have broader application in time series forecasting, it is not only effective for over-fitting problems but also has promoted the model accuracy considerably.

Existence of Superdirective Radiation Modes in Thin-Wire Nanoloops

The problem of obtaining broadband superdirective radiation from an electrically small, easy to manufacture antenna is among the most challenging and elusive problems in electromagnetics. Superdirective arrays tend to be narrowband and sensitive to tolerancing, while a single superdirective radiator typically requires a very complicated and difficult to manufacture design. In this Article, we report on a new and transformative discovery, the fact that broadband superdirectivity naturally occurs for a single thin-wire nanoloop of the appropriate material composition and size. Full-wave simulations have revealed end-fire directivity of above 4.0 (6 dBi) for a nanoloop with radius less than 0.2 wavelength. This surprising phenomenon is explained in two ways: by comparison with two-element superdirective arrays and via a spherical multipole decomposition. This finding offers a solution to the problem of the inherently short-range communication of nanodevices and thus had the potential to strongly impact the f...

Missing piece of the puzzle in the science of consciousness: Resting state and endogenous correlates of consciousness.

Consciousness still stands as one of the most interesting and the most elusive problems of neuroscience. Finding its correlates is the first step toward its satisfactory explanation. Several theories have proposed its correlates but none of them seem to be generally accepted even though most of them share some very similar elements. These elements are the activity of the thalamus, which is considered by some as the central region for consciousness, and gamma synchronization, which should be the general principal for the emergence of conscious experience. However, all of these proposed theories share one characteristic and that is that they do not take into consideration the recently discovered endogenous activity of the brain, which is generally associated with the default mode network. Although the activity of this large scale brain network is in correlation with various levels of consciousness it is still missing in discussions of consciousness. This review recognizes the importance of endogenous activity and points out the important discoveries of endogenous activity that could be an important step toward a satisfactory explanation of consciousness.

Introduction to the theme issue 'Cerebral cartography: a vision of its future'.

Introduction to the theme issue 'Cerebral cartography: a vision of its future'.

Agricultural origins from the ground up: archaeological approaches to plant domestication.

The timing, geographical locations, causes, and consequences of crop domestication have long been major concerns of archaeologists, and agricultural origins and dispersals are currently more relevant than ever to scientists seeking solutions to elusive problems involving food insecurity and global health disparities. Perennial research issues that archaeologists continue to tackle include (1) thinking outside centers of origin that were based on limited and insufficient past knowledge; (2) distinguishing between single and multiple domestications of specific crops; (3) measuring the pace of domestication; and (4) decoupling domestication from agricultural economies. Paleoethnobotanists have expanded their toolkits to include analysis of ancient and modern DNA and have added increasingly sophisticated techniques in the field and the laboratory to derive precise chronological sequences to assess morphological changes in ancient and often fragmentary archaeobotanical remains and to correctly interpret taphonomy and context. Multiple lines of archaeological evidence are ideally brought together, and whenever possible, these are integrated with information from complementary sources. We discuss current perspectives and anthropological approaches to research that have as their goals the fuller and broader understanding of ancient farming societies, the plants that were domesticated, the landscapes that were created, and the culinary legacies that were passed on.

Rural Development Initiatives and the Activities of NonGovernmental Organisations (Ngos): Implication for Social Work Intervention

The paper addresses the issues of rural development initiatives and the activities of non-government organizations in the promotion and development of individuals and groups in the society today. The effectiveness of the role performance of NGOs measured against their ability to engender the preconditions to the attainment of rural development objectives. NGOs are yet to wholly generate these success ingredients. This failure is due to the paradox of performance at different levels in society. The dynamics of operations of NGOs produce some latent inhibiting consequences which constrain the attainment of anticipated grassroots development. Thus, this paper identifies some of these shortcomings and concludes that concerted global research efforts are needed to understand better these nascent but elusive problems and to offer management strategies. The paper further shows that despite the existence of NGOs across the nation, their activities show their desire to propagate and run their agenda of creating wealth for their organization. It is recommended that most social workers and social development experts should be involved in rendering professional services through NGO activities in order to enhance development in society.