Expert Observers Research Articles

Calibrating Human Attention as Indicator Monitoring #drought in the Twittersphere

AbstractState climatologists and other expert drought observers have speculated about the value of monitoring Twitter for #drought and related hashtags. This study statistically examines the relationships between the rate of tweeting using #drought and related hashtags, within states, accounting for drought status and news coverage of drought. We collected and geolocated tweets, 2017–18, and used regression analysis and a diversity statistic to explain expected and identify unexpected volumes of tweets. This provides a quantifiable means to detect state-weeks with a volume of tweets that exceeds the upper limit of the prediction interval. To filter out instances where a high volume of tweets is related to the activities of one person or very few people, a diversity statistic was used to eliminate anomalous state-weeks where the diversity statistic did not exceed the 75th percentile of the range for that state’s diversity statistic. Anomalous state-weeks in a few cases preceded the onset of drought but more often coincided with or lagged increases in drought. Tweets are both a means of sharing original experience and a means of discussing news and other recent events, and anomalous weeks occurred throughout the course of a drought, not just at the beginning. A sum-to-zero contrast coefficient for each state revealed a difference in the propensity of different states to tweet about drought, apparently reflecting recent and long-term experience in those states, and suggesting locales that would be most predisposed to drought policy innovation.

Semi-automated Analysis of Ventilation-Perfusion Single-Photon Emission Tomography in the Diagnosis of Pulmonary Embolism - Does it add extra value?

Diagnosis of pulmonary embolism using V/P-SPECT may include the application of advanced image-processing techniques to identify V/P-mismatches. Aim of this study was to evaluate the benefit in clinical decision making in the diagnosis of pulmonary embolism.by whether adding to conventional reading a software that automatically calculates and visualizes the ventilation/perfusion-quotient pixel by pixel. 63 consecutive patients with a clinical suspicion of PE who underwent V/P-SPECT were included in this retrospective study. Images were randomly ordered both for standard as well as for software-assisted reading using V/P-quotients. Studies were read independently by 2 experienced and 2 inexperienced raters. Diagnostic performance and observer agreement of all readers and both reading methods were determined. Expert observers consistently achieved a high diagnostic accuracy both in conventional as well as in software-assisted reporting (sensitivity: 0.94 vs. 0.94, specificity: 0.96vs. 0.97, LR+: 17.32 vs. 28.86, LR- stayed constant at 0.06). For inexperienced readers, diagnostic performance improved: sensitivity raised from 0.74 to 0.85 and specificity from 0.86 to 0.95, LR+ raised from 5.20 to 15.69, LR- decreased from 0.31 to 0.16. Inter-rater reliability (Fleiss' κ) improved from 0.63 to 0.86 by using V/P quotient. Benefit from a software-tool that calculates V/P-ratio automatically is only small when used by experienced physicians If inexperienced readers use the software, the diagnostic accuracy increases. Images generated by automated calculation of V/P-mismatches are easy to read and their use might help to standardize and objectify interpretation of V/P-SPECT in the diagnosis of PE.

Character Synthesis of Ballet Archetypes on Robots Using Laban Movement Analysis: Comparison Between a Humanoid and an Aerial Robot Platform with Lay and Expert Observation

Imitation of human movement by robots is an important area of research to create expressive systems that are able to interact with humans in social settings. One lens through which imitation may be investigated is that of character archetypes, commonly found in human story-telling. Classical ballet, a form of story-telling through movement, makes extensive use of such archetypes. This paper reviews how Laban Movement Analysis creates a descriptive taxonomy in which features of interest may be identified and reported from human performers to robotic platforms, specifically for a BeBop aerial drone and a Nao humanoid platform. To determine the success of this approach, the paper also presents evaluation by lay human viewers that validates the character transfer. Moreover, this paper offers more nuance into this evaluation by querying two specialized groups of experts, which frequently deviated from lay ratings and, thus, offer deeper insight into both the success of the character transfer and the importance of prior training in movement perception. This work may be useful in human-facing scenarios where character archetypes facilitate engagement, identification, and understanding between robots and human counterparts. Further, it highlights nuances in working with expert artists to create broadly applicable designs.

The Tale of Two Capital Cities: the Effects of Urbanisation and Spatial Planning Heritage in Zimbabwe and Zambia

This paper examines the effects of urbanisation in the capital cities of Zimbabwe and Zambia with specific reference to their inherited spatial planning systems. Many cities around the world are faced with urbanisation challenges, owing largely to population growth caused rural-urban migration. Most of this urbanisation occurs as people search for favourable economic opportunities and a better life. The paper analyses the colonial spatial planning legacy of the two countries, highlighting how inherited spatial planning practices in Zimbabwe and Zambia has continued to influence urban development in the rapidly urbanising cities of Harare and Lusaka. Data was obtained from document reviews and the analysis of secondary data. Some data was acquired through interviews from expert planners and observations. The results revealed that urbanisation is an enduring phenomenon in these capital cities, and the growth of slums and informal settlements is very pronounced there. Although efforts have been made to address challenges associated with urbanisation, these have not been sufficient. Moreover, although Harare and Lusaka are experiencing rapid urbanisation, minimal priority is given to deliberately reviewing their spatial planning systems and addressing their urbanisation challenges. Noteworthy attempts have been made to control urbanisation in Harare and Lusaka, but these have largely been inadequate due to the lack of will to review the adopted colonial spatial planning frameworks in Zimbabwe and Zambia. There is need, therefore, for strong spatial planning institutions and sustainable statutory frameworks that address contemporary urbanisation problems in these Third World cities.

DETECTION OF PLANT LEAF DISEASES USING IMAGE PROCESSING

Agriculture is no doubt a very crucial industry to Malaysia in terms of the amount of GDP it is contributing. It would definitely be a nightmare if anything bad happens to the industry. As we all may know, plant is prone to diseases and it is often inevitable. The best way to keep the impact as minimal as possible is to be able to detect the diseases as quickly as possible. The traditional way of identifying plant diseases is done by the manual observation of experts of the field. This method is very expensive, tedious, inaccurate and consumes a lot of time as well. With the advent of image processing throughout the years, automatic detection of plant disease has been made possible by capturing and processing the image of the plant leaves. By going through the few image processing phases, like acquisition of image, pre-processing, segmentation, extraction of features and classification, the condition of the plant, whether infected or not, will be identified. There are several techniques that has emerged recently to carry out the process for each of the phases like SVM, GLCM, Otsu’s thresholding and etc. MATLAB is a powerful software that are often used for image processing and machine learning algorithms. In this project, the system is being implemented using MATLAB to detect plant diseases through processing image of the plant leaves. In this project, comparison between using k-means clustering and Color Thresholding has been done to evaluate whether which performs better on the target dataset. Moreover, feature extraction of the image will be done using a pretrained CNN model which is ResNet-50 and GLCM to compare whether which performs better as a feature extractor to extract features of the leaf images. SVM are being used as a classifier in this project to classify the diseases on the leaf. Overall the project was able to achieve a maximum classification accuracy of 96.63%.

К вопросу о развитии рыболовства у калмыков в дореволюционный период

The article seeks to examine respective sources and show that the Oirats – ancestors of Kalmyks – had been engaged in fishery activities since ancient time, and on arrival in Russia’s borders borrowed neither fishing techniques nor terms but would rather make use of their original ones. Materials and Methods. The work analyzes historical data related to fishing practices of the Kalmyks and published in various scientific papers. It also involves quite a number of expert observations. The study employs historical genetic, historical systemic, and historical comparative research methods. Results and Conclusions. A number of scholars to have dealt with Kalmyk studies believed that since ancient time the Kalmyks had been engaged exclusively in nomadic livestock breeding, leaving any other branches of economic production totally undeveloped, and their fishing activities in the Lower Volga, thus,viewed as a desperate measure caused by impoverishment only. The study shows the Oirat population had been well familiar with this industry back in their historical ancestral lands. Already the early 18th century witnesses the adoption of central and provincial government decrees supposed to regulate quite shaped fishery activities and distinguish Kalmyk-occupied fishery areas from those of Russian settlers. In the mid-to-late 19th and early 20th centuries, fishery proved central to economies of Kalmyk-inhabited districts adjacent to the Volga and Caspian Sea. It can also be noted that the development of fishing practices within the Kalmyk community definitely strengthened its economic basis and increased vital resources.

The Use of Android Game to Improve Impaired Hearing Student Vocabulary Mastery

In general, problems that occur in the actual are the discovery of instruments that have not been tested for problem solving abilities. The aim of this research is to reveal the content validity and interrater reliability of the instrument for evaluating the problem solving abilities that have been prepared. The research method is used a quantitative description by 3 expert judgments, they are experts in research and evaluation, mathematics education experts, and mathematics teachers. The instrument was developed in the form of an expert observation sheet with 3 aspects of assessment, they are the aspect of content eligibility, construction aspects, and language aspects, which of each aspect has 4 categories, which are very relevant, relevant, quite relevant, and highly irrelevant. Data were analyzed using the Aiken's V formula to determine the level of instrument validity and to determine the level of consistency / constancy between assessors using Instraclass Correlation Coefficient (ICC) analysis with the help of SPSS version 23.0. the results of analysis of the content validity of all items valued above 0.3 which means that all aspects assessed by experts are valid. Interrater reliability test using ICC obtained a value of 0.516, which means that all aspects of the instrument for evaluating problem solving abilities that have been rated have a level of consistency. Thus, the instrument of problem-solving ability that has been tested for validity and reliability can be used by educators to determine the level of students' problem solving abilities appropriately

Are Self-Assessment and Peer Assessment of Added Value in Training Complex Pediatric Surgical Skills?

Self-assessment aids "reflection-before-practice," which is expected to result in a better understanding of one's strengths and weaknesses and consequently a better overall performance. This is, however, rarely used in surgical training. This study aims to evaluate the correlation between self-, peer-, and expert assessment on surgical skills of pediatric surgical trainees. A competency assessment tool for the posterior sagittal anorectoplasty (CAT-PSARP) was previously developed and validated. During international hands-on pediatric colorectal workshops in 2019 and 2020, participants practiced the PSARP on an inanimate anorectal malformation model. They were assisted by a peer and assessed by two independent expert observers, using the CAT-PSARP. After the training session, both self- and peer assessment were completed, using the same CAT-PSARP. A total of 79 participants were included. No correlation was found between the overall CAT-PSARP scores of the expert observers and the self-assessment (r = 0.179, p = 0.116), while a weak correlation was found between experts and peer assessment (r = 0.317, p = 0.006). When comparing the self-assessment scores with peer assessment, a moderate correlation was found for the overall performance score (r = 0.495, p < 0.001). Additionally, the participants who were first to perform the procedure scored significantly better than those who trained second on the overall performance (mean 27.2 vs. 24.4, p < 0.001). Participants, peers, and experts seemed to have a unique view on the performance during training because there was little correlation between outcomes of the trainees and the experts. Self-assessment may be useful for reflection during training; however, expert assessment seems to be essential for assessment of surgical skills.

Physicians’ and nurses’ work time allocation and workflow interruptions in emergency departments: a comparative time-motion study across two countries

BackgroundGlobally, emergency department (ED) work is fast-paced and subject to interruptions, placing high coordination and communication demands on staff. Our study aimed to compare ED staffs’ work time allocation and...

Preventative measures in form of a restriction of certain actions, collateral, and house arrest: questions of their correlation and practices of application

The subject of this research is the norms of criminal procedure legislation regulating the application of preventative measures in criminal proceedings, as well as court decisions made on the basis of the results of processing applications on selection of preventative measures. Based examination of law enforcement practice, the expert observations and proposals in scientific literature, the author carefully analyzes the flaws of the current system of preventative measures in the criminal procedure, problematic aspects of correlation of restriction of certain actions, collateral, house arrest, as well as separate restriction, imposition of which upon a suspect (accused) is allowable in accordance with Part 6 of the Article 105.1 of the Criminal Procedure Code of the Russian Federation. The conclusion is made that the current system of preventative measures is not perfect, and practical application of various preventative measures reveals the formality of the established hierarchical structure of preventative measures in the criminal procedure legislation from soft to a more strict form. Analysis of case law demonstrates the it is often impossible to clearly and unambiguously demarcate the measures of prevention on form of a restriction of certain actions and collateral, restriction of certain actions and house arrest, which leads the author to conclude on the reasonableness of regulation of restriction of certain actions as another form of procedural compulsion.

Ho.Re.Ca. logistics and European medieval structured cities: A search for cost generators

This paper examines the current organisation of Hotel-Restaurant-Café/Catering (Ho.Re.Ca.) logistics in medieval structured cities from a microeconomic perspective. The paper aims to distinguish Ho.Re.Ca. specific cost generators and to provide different stakeholders with guidelines on improving the efficiency and sustainability of delivery operations. Therefore, a Ho.Re.Ca. specific costs function has been developed and calculates both internal (economic) as external (social and environmental) costs. The developed cost function follows a 3-steps approach: exploratory expert interviews and observations, the development of the cost function and, validation by the same business experts. The main findings are that mostly the characteristics of the goods determine the way Ho.Re.Ca. goods are delivered nowadays. However, the location of demand and supply for the goods and the specific handling conditions also have a significant influence. The following specific cost generators are distinguished: all labour-based activities rise the internal costs structures substantially. Congestion and city quality issues are identified as major external costs generators. Originating from these results, transport operators should focus on improving labour-based activities such as the service time by investing in e.g. innovative (un)loading equipment. For governments, the internalisation of congestion-related externalities by e.g. road pricing is decisive.

Applying Hierarchy of Expert Performance (HEP) to investigative interview evaluation: strengths, challenges and future directions

The purpose of this paper is to systematically examine the research literature on the decision of expert interviewers within the theoretical framework of the Hierarchy of Expert Performance (HEP). After providing an overview of the HEP framework, existing research in the investigative interviewing at each of the eight levels of the HEP framework is reviewed. The results identify areas of strength in reliability between experts’ observations (Level 2) and of weakness in reliability between experts’ conclusions (Level 6). Biases in investigative interview experts’ decision making is also revealed at biasability between expert conclusions (Level 8). Moreover, no published data are available in reliability within experts at the level of observations (Level 1) or conclusions (Level 5), biasability within or between expert observations (Level 3 and 4) and biasability within expert conclusions (Level 7). The findings highlight areas where future research and practical endeavour are much needed for the investigative interview.

Workflow disruptions and provider situation awareness in acute care: An observational study with emergency department physicians and nurses

BackgroundThe fast-paced and rapidly changing environment of an Emergency Department (ED) requires providers to have a high level of situation awareness (SA). However, acute clinical care also encompasses a multitude of interruption-laden work processes that might degrade SA. It is therefore important to understand how frequent interruptions affect ED provider cognition in general and SA in particular. ObjectiveWe aimed to examine how sources and contents of provider workflow interruptions influence situation awareness of ED physicians and nurses. MethodsThis prospective, multi-method study combined standardized observations, self-reports of ED providers, and ED administrative data of staffing and patient load. Expert observers identified ED providers’ workflow interruptions during 90min observation sessions. Afterwards, each provider reported perceived disruptiveness and situation awareness. Controlling for patient load, patient acuity and staffing, we conducted regression analyses to explore prospective associations between interruptions and provider outcomes. ResultsDuring 74 observation sessions of overall 110h and 40min, we observed 1205 workflow interruptions (mean rate: 10.9 interruptions/hour). Provider situation awareness was fairly high (M = 7.10; scale 0–10) with no difference between ED physicians and nurses. After controlling for ED workload data, we observed that high rates of interruptions were associated with lower levels of situation awareness (β = −0.27). Further analyses revealed that particularly interruptions by telephone/beeper, technical malfunctions as well as interruptive communication related to completed cases were correlated to low SA. DiscussionThis study in a naturalistic ED setting shows that ED physicians and nurses continuously cope with disruptions and interruptions. Our findings reveal that highly interruptive workflow environments impede providers' situation awareness. Moreover, it sheds light on specific sources and contents of interruptions that influence providers’ SA in acute care. ConclusionFrequent workflow interruptions can degrade ED providers’ situation awareness. A deeper understanding of how avoidable and unavoidable interruptions affect provider cognitions with particular focus on social and technology-related disruptions is required. Further emphasis should be placed on the effective application of work re-design in this context to foster safe and efficient patient care.

De la declaración a la existencia de los derechos humanos. Consideraciones de fenomenología y ontología social

En este artículo reflexiono sobre la posibilidad de conceptualizar los derechos humanos como hechos institucionales, lo cual permite enmarcarlos en una perspectiva más amplia que las meramente jurídicas y morales. La propuesta se basa en la ontología social de John Searle, aunque intento replantearla desde la fenomenología de Edmund Husserl y la teoría de los actos sociales de Adolf Reinach. En la parte final introduzco problemáticas relacionadas con el papel de los Estados nacionales en la institucionalización de los derechos humanos. Para ello me apoyo en la idea de Hannah Arendt de que los derechos humanos presuponen el derecho a tener derechos y la pongo en relación con observaciones más recientes de especialistas.

Exploring the use of high and low demand simulation for human performance assessment during multiorgan retrieval with the joint scrub practitioner

IntroductionThe National Organ Retrieval Service (NORS) 2015 review recommended a Joint Scrub Practitioner for abdominal and cardiac teams during combined organ retrieval. To evaluate the feasibility of this role, and...

Strategies for evaluating self-efficacy and observed success in the practice of yoga postures for therapeutic indications: methods from a yoga intervention for urinary incontinence among middle-aged and older women

BackgroundMost clinical investigations involving yoga lack adequate description of the specific yoga elements, including physical postures. Few studies have measured self-efficacy regarding the performance of yoga postures or assessed observed success in performing postures.MethodsWe developed and piloted several tools to evaluate self-efficacy and observed success in practicing yoga in the context of a randomized feasibility trial of an Iyengar-based yoga intervention for urinary incontinence in ambulatory women ≥50 years. At the end of the 12-week yoga intervention involving twice weekly group yoga classes and once weekly home practice, participants rated their self-efficacy in performing each of the included 15 yoga postures on a 5-point Likert scale. During the 12th week, an expert yoga consultant observed participants and rated their competency in performing postures on a 5-point scale. Participants completed a questionnaire about self-efficacy in adhering to home yoga practice. We examined the distribution of and correlations between scores on the above measures.ResultsAmong 27 participants (mean age 65 years), the range of means for self-efficacy ratings for individual postures was 3.6 to 4.5. The range of means for observed competency ratings for individual postures was 3.3 to 5.0. Mean self-efficacy rating for confidence in adhering to the assigned once-weekly home yoga practice was 2.8 (range 1 to 5). Posture self-efficacy was inversely correlated with participant age (p = 0.01) and positively correlated with self-reported physical function (p = 0.03) and mobility (p = 0.01). No significant correlations were found between posture self-efficacy scale scores and expert-observed yoga competency ratings or practice adherence self-efficacy scores.ConclusionsThese measures hold promise for advancing yoga research and practice by describing methods to: 1) measure self-efficacy in performing specific yoga postures; 2) use an expert observer to assess participants’ competence in performing yoga postures; and 3) measure self-efficacy in adhering to home practice. These proposed measures can be used to describe specific components of yoga interventions, to assess whether study participants are able to learn to practice physical aspects of yoga and/or maintain this practice over time, as well as to investigate relationships between self-efficacy and competency in performing yoga postures to achieve specific health outcomes.Trial registrationClinicalTrials.gov, NCT02342678, January 21, 2015.

PENILAIAN IMPLEMENTASI KURIKULUM 2013 PADA MATA PELAJARAN PENJASKES TINGKAT SEKOLAH DASAR NEGERI 4 MEMPAWAH HILIR

AbstractThis study aims to find out:1) Curriculum 2013 implementation, 2) describe the constraints faced in the implementation of the curriculum 2013, 3) the strategy used in the implementation 2013 curriculum in the orchestra education in public elementary school 4 Mempawah. This study is an evaluation research using the CIPP (Contex, Input, Process and Product) developed by Stufflebeam. Data was obtained through curriculum expert validation questionnaires, observation and interviews. Data analysis was carried out qualitative. The results of the study show that: 1) the implementation of the Curriculum 2013 has largely gone smoothly, from 4 schools incorporated only 1 school has not fully planned the implementation of Curriculum 2013, due to the lack of socialization and assistance to teacher and the lack of available facilities at school, 2) the obstacles  faced in the implementation of the  Curriculum 2013 were the lamitations of orchestra teacher and the limited of  infrastructure to support practical activities and the lack of supporting books, library and internet network. 3) the strategy to overcome the obctacles in the implementation of curriculum 2013 that needs to be prepared furthur is to make good planning based on needs analysis and the existence of good synergies between the central goverment and the provincial as well as local government. There are still many confusions, this is due to the large number of assesment components that must be carried out as demands of the Curriculum 2013. Keywords: Assesment Implementation of the Curriculum 2013, Physical Education

Time series clustering to examine presence of decrement in Parkinson's finger-tapping bradykinesia.

Parkinson's disease is diagnosed based on expert clinical observation of movements. One important clinical feature is decrement, whereby the range of finger motion decreases over the course of the observation. This decrement has been assumed to be linear but has not been examined closely.We previously developed a method to extract a time series representation of a finger-tapping clinical test from 137 smart- phone video recordings. Here, we show how the signal can be processed to visualize archetypal progression of decrement. We use k-means with features derived from dynamic time warping to compare similarity of time series. To generate the archetypal time series corresponding to each cluster, we apply both a simple arithmetic mean, and dynamic time warping barycenter averaging to the time series belonging to each cluster.Visual inspection of the cluster-average time series showed two main trends. These corresponded well with participants with no bradykinesia and participants with severe bradykinesia. The visualizations support the concept that decrement tends to present as a linear decrease in range of motion over time.Clinical relevance- Our work visually presents the archetypal types of bradykinesia amplitude decrement, as seen in the Parkinson's finger-tapping test. We found two main patterns, one corresponding to no bradykinesia, and the other showing linear decrement over time.

Developing an Innovation Management Strategy for Educating Managers on Disaster risk reduction

In modern conditions of increasing threats, challenges, dangers and threats of various types, it is necessary to create a system of innovative training of managers. The paper considers the formation of an innovation management strategy for education of managers on disaster risk reduction and the development of methodological support for this activity. In the course of work to achieve the goal, key tasks were solved: the organizational basis for the formation of an integrated education system was justified, proposals for creating an information and organizational learning innovation were developed, and the basis for a new unified innovative information and communication educational platform was created. Methodological recommendations for innovative training of managers are proposed. The research methodology provides for the creation of innovative and technological matrixes of Executive education based on modern methods of analysis and synthesis, expert assessments, modeling, analogies, and observation. The results of the research are the main provisions of the innovation management strategy for education of managers on disaster risk reduction, organizational and methodological support for this activity. On their basis, a comprehensive system of training managers has been created, and modern training programs and practices in the field of disaster management have been introduced. Recommendations for the consolidation of key modern achievements of science and technology in the educational sphere are formulated. The study may be of interest to state authorities in the formation and implementation of the state strategy of innovative management of education of managers, which provides a high modern level of training.

Model-based unsupervised clustering for distinguishing Cuvier's and Gervais' beaked whales in acoustic data

Passive acoustic monitoring (PAM), particularly autonomous platforms, offers many advantages in monitoring phonating deep-diving marine mammals in oceanic environment. Relevant data can be obtained day and night continuously over long durations and in any weather conditions. It provides a cost-efficient solution with greater detection ranges when compared to traditional large research vessel and aerial visual surveys requiring keeping expert observers on station for long periods of time and relying on good visibility and calm seas. Therefore, PAM is becoming a preferred tool to assess population dynamics trends and health of deep-water marine mammal stocks. However the large volumes of collected data require robust automatic detection and classification algorithms to identify marine mammals in recordings. As for beaked whales, one of the challenging automatic processing goals is the identification of different species to advance our understanding of their role in the marine ecosystem. At present, traditional detection and classification methods employ searches for acoustic events above a user-defined signal-to-noise ratio threshold in the frequency band of interest and further rely on an experienced operator's manual inspection for species classification and removal of false positives. Current passive monitoring data collection systems yield large volumes of acoustic data, therefore a manual classification approach becomes very time-consuming and impractical. This paper focuses on developing a multi-stage automatic classifier for beaked whale species. The proposed method utilizes unsupervised machine clustering of signal attributes extracted from potential detection events flagged by an energy-band detector. The proposed algorithm was benchmarked against a manually annotated workshop dataset and applied to acoustic data collected in the northern Gulf of Mexico. The algorithm classifies beaked whale species in automatic mode with minimal operator involvement only at the validation stage. When compared with the manually annotated classification dataset, the proposed method achieved a recall rate of 82.8% for Cuvier's and 77.9% for Gervais' species in automatic mode. New insights on habitat use by different species of beaked whales in the Gulf of Mexico were gained when using the species-specific classifier. The high spatial resolution acoustic monitoring results showed that the habitat preferences of two dominating beaked whale species in the Gulf of Mexico support the habitat division (ecological niche) hypothesis.