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A computerized adaptive test (CAT) is usually administered to small groups of examinees at frequent time intervals. It is often the case that examinees who take the test earlier share information with examinees who will take the test later, thus increasing the risk that many items may become known. Item overlap rate for a group of examinees refers to the number of overlapping items encountered by these examinees divided by the test length. For a specific item pool, different item selection algorithms may yield different item overlap rates. An important issue in designing a good CAT item selection algorithm is to keep item overlap rate below a preset level. In doing so, it is important to investigate what the lowest rate could be for all possible item selection algorithms. In this paper we rigorously prove that if every item has an equal possibility to be selected from the pool in a fixed-length CAT, the number of overlapping items among any α randomly sampled examinees follows the hypergeometric distribution family for α ≥ 1. Thus, the expected values of the number of overlapping items among any randomly sampled α examinees can be calculated precisely. These values may serve as benchmarks in controlling item overlap rates for fixed-length adaptive tests.
There are a number of microphysics and transport processes that can be extremely important to suppress or enhance the growth of these instabilities. I will provide a detailed description of how the hydrodynamic instability evolutions can be modified by incorporating the viscosity, surface tension, diffuse interface, and compressibility of the flows into the governing equations and growth rates.
Complexity stratification for CHD is an integral part of clinical research due to its heterogenous clinical presentation and outcomes. To support our ongoing research efforts into CHD requiring disease severity stratifications, a simplified CHD severity classification system was developed and verified, with potential utility for clinical researchers without specialist CHD knowledge or access to clinical/medical records.
Method:
A two-tiered analysis approach was undertaken. First-tier analysis included the audit of a comprehensive system based on: i) timing of intervention, ii) cardiac morphology, and iii) cardiovascular physiology using real patient data (n = 30), across 10 common CHD lesions. Second-tier analysis allowed for a simplified version of the classification system using morphology as a stand-alone predictor. Twelve clinicians of varying specialities involved in CHD care ranked 10 common lesions from least to most severe based on typical presentation and clinical course.
Results:
First-tier analysis identified that cardiac morphology was the principal driver of complexity. Second-tier analysis largely confirmed the ranking and classification of the lesions into the broad CHD severity groups, although some variation was noted, specifically among non-cardiac specialists. This simplified version of the classicisation system, with morphology as a stand-alone predictor of severity, allowed for effective stratification for the purposes of analysis.
Conclusion:
The findings presented here support this comprehensive and simple CHD severity classification system with broad utility in CHD research, particularly among clinicians and researchers with limited knowledge of CHD. The model may be applied to produce locally relevant research tools.
Chapter 26 analyzes the political economy of higher education finance from an international perspective. This analysis documents and explains the increasingly stratified nature of higher education institutions by social class and, often, by level of public financing per student. It discusses the possible economic rationale for such stratification and unequal public investment in different strata. It also analyzes why some countries’ governments assume a high fraction of the cost of higher education expansion and others make families and students bear most of the cost. This comparative international analysis suggests that politics play a very important role in defining how higher education is financed and how that financing is used to shape the higher education system. The chapter makes the case that the “public” function of higher education is highly contested politically because of its direct role in providing access to higher productivity jobs and higher earnings figured in discussions about the worldwide trend toward expanding higher education through private institutions (many, for profit), and, in some societies, through increasing the share of private tuition payments in the financing of public institutions.
This chapter presents a view on context as understood within functional models of language, specifically the theoretical framework of Systemic Functional Linguistics (SFL). Amongst the functional approaches to language, SFL is recognized as a framework which has maintained an account of context that has prioritized its relationship with lexicogrammar, allowing it to make a causal connection between culture and language. The aim of this chapter is to highlight and explain the principal ways in which context works within the SFL framework and explore the main themes and parameters which situate context within an integrated theory of language as a semiotic resource. As no theory emerges in a vacuum, the first part of the chapter will consider the historical development of context as a concept within SFL theory with reference to how context is situated in other related functional grammars. Following this, we examine two areas of challenge related to the approach to context outlined in the chapter. Finally, the chapter concludes with closing remarks and key directions for future research in this area.
How international (and other social) systems are stratified – how social positions are arranged in ranked relations of super-, sub-, and co-ordination – is obviously central to their structure and functioning. This chapter looks at two broad types of vertical differentiation: single (or convergent) hierarchies and heterarchies (or multiply ranked orders). I begin with a 2x2 typology of hierarchies, based on whether they are restricted to a single issue or institution and whether they have a single axis of stratification. Among multi-layer systems, which are the norm in international relations, I look at various types of “states systems,” which have different types of relations between more or less autonomous polities; “imperial” systems, which have a single axis of super- and subordination; and “heterarchies,” which have multiple axes of stratification. The chapter concludes by considering the distinctive ways in which typologies explain.
This chapter advocates viewing the structures of international political systems through the lens of multiple dimensions of social differentiation; the structured processes by which social actors and positions are produced, populated, related, reproduced, and transformed. Social differentiation involves, at minimum, establishing who has what authority over whom with respect to which activities; that is, differentiating actors, activities, and authorities (which usually are complexly interrelated). And in addition to institutional and normative dimensions, which are notoriously excluded from the Waltzian account of structure, social differentiation has important material or geo-technical dimensions that are also ignored in the Waltzian account (which is not, as is often claimed, materialist). More generally, I argue that rather than seek to identify a small number of structural models composed of a few elements, we should aim for a checklist of dimensions of differentiation that illuminate some recurrently important features of the structures of some social and political systems of interest.
Scholars have attempted to theorise the social structure of the international system from the perspective of the ‘middle powers’ for decades. However, scholars have struggled to agree on the essential dispositional characteristics of this category of actors, stunting theoretical progress. Drawing on sociological and literary approaches to the rhetoric of the ‘middle class’ in domestic societies, this article shifts the terms of this debate away from asking who the ‘middle powers’ are or what their ‘essence’ is, to ask what actors do with the term in practice. Combining this with and contributing to scholarship on hierarchy in international relations, I recast ‘middle powers’ as a category of practice and argue that one of the term's main uses is to differentiate certain status-anxious states – that hold no real prospect of achieving great power status – from ‘small states’ that occupy the lowest stratum of stratification within the ‘grading of powers’. Following an illustrative case study of Australian and Canadian attempts to establish the ‘middle power’ category in the 1940s, the article then outlines the contributions of the argument for the study of status and hierarchy in world politics.
Chapter 1 presents the purpose of the book – i.e. describing how a text-based description of three world languages can be developed. The Systemic Functional Linguistic theory informing these descpriptons is introduced, including modellng of context and discourse semantics,and the basic theoretical parameters of metafunciton, rank and stratification.The nature argumentation in relation to grammar description is outlined.
Recent genetic evidence implicates glutamatergic-receptor variations in schizophrenia. Glutamatergic excess during early life in people with schizophrenia may cause excitotoxicity and produce structural deficits in the brain. Cortical thickness and gyrification are reduced in schizophrenia, but only a subgroup of patients exhibits such structural deficits. We delineate the structural variations among unaffected siblings and patients with schizophrenia and study the role of key glutamate-receptor polymorphisms on these variations.
Methods
Gaussian Mixture Model clustering was applied to the cortical thickness and gyrification data of 114 patients, 112 healthy controls, and 42 unaffected siblings to identify subgroups. The distribution of glutamate-receptor (GRM3, GRIN2A, and GRIA1) and voltage-gated calcium channel (CACNA1C) variations across the MRI-based subgroups was studied. The comparisons in clinical symptoms and cognition between patient subgroups were conducted.
Results
We observed a “hypogyric,” “impoverished-thickness,” and “supra-normal” subgroups of patients, with higher negative symptom burden and poorer verbal fluency in the hypogyric subgroup and notable functional deterioration in the impoverished-thickness subgroup. Compared to healthy subjects, the hypogyric subgroup had significant GRIN2A and GRM3 variations, the impoverished-thickness subgroup had CACNA1C variations while the supra-normal group had no differences.
Conclusions
Disrupted gyrification and thickness can be traced to the glutamatergic receptor and voltage-gated calcium channel dysfunction respectively in schizophrenia. This raises the question of whether MRI-based multimetric subtyping may be relevant for clinical trials of agents affecting the glutamatergic system.
In order for democratic deliberative interactions in educational settings to fruitfully occur, certain favorable conditions must obtain. In this chapter, I chiefly concern myself with one of these putative conditions, namely that of school integration, believed by many liberal scholars to be necessary for consensus-building and legitimate decision-making. I provide a critical assessment of the belief that integration is a necessary facilitative condition for democratic deliberation in the classroom. I demonstrate that liberal versions of democratic deliberation predicated on this condition are puzzlingly inattentive both to the inevitability of segregation, as well as the inequities occasioned by “school integration.” I then move to probe the possibilities for democratic education in the absence of integration. I argue that neither the possibilities for deliberation nor the cultivation of civic virtue turn on an environment being “integrated.” Indeed, some kinds of segregation may be more conducive to fostering both deliberation and civic virtue.
Chapter 4 begins by exploring the productive tension that can exist between gestural articulation and formal continuity in Schubert’s music, and its affinity with Schubert’s paratactic forms which exploit unexpected disjunction as a formal premise. It focuses on the expositional interpolations in Schubert’s sonatas that exhibit characteristics normally associated with development sections. The three analytical case studies that follow have been chosen for their distinctive approach to this formal practice, and demonstrate its early stages of development in D36/i and D353/i as well as a mature example, D804/i. Three fundamental questions underline my analyses: first, in what sense do the interpolations in Schubert’s first-movement expositions function as development (D353/i); second, the question of whether or not synthesis of the formal dialectic is achieved (D36/i), and finally, what the implications of this are for the articulation of a lyrically conceived teleology (D804/i). This chapter also contains a methodological interlude wherein I define my extension of Edward T. Cone’s concept of stratification to Schubert’s music and its relevance to the sonatas.
We obtain a complete topological classification of $k$-folding map-germs on generic surfaces in $\mathbb {R}^3$, discover new robust features of surfaces and recover, in a unified way, many of the robust features that were obtained previously by considering the contact of a surface with lines, planes or spheres.
A large body of archaeological and anthropological research suggests that warfare is more common when societies are stratified. This is true for societies based on either sedentary foraging or agriculture. We argue that warfare in stratified societies does not require climatic or technological shocks, and results from competition among rival elites over land rent. In our model, elites recruit specialized warriors by offering booty in the event of victory, which may involve elevation to elite status. After each elite recruits an army, the rival elites must decide whether to attack, defend, or flee. We solve for the equilibrium at the combat stage as a function of army sizes, and use backward induction to solve for the equilibrium army sizes. If stratification is relatively low (the land rents are small relative to commoner food income), elites can sometimes win through intimidation without fighting an actual war. But if stratification is high, such equilibria disappear and the only outcome is a mixed-strategy equilbrium with a positive probability of open war. In either case, successful elites expand their territory. Fiscal constraints on the capacity of elites to recruit warriors can sometimes limit warfare, but do not prevent it entirely.
This chapter constructs a formal model of our hypothesis from Chapter 9 about the rise of Uruk. We assume there are many open sites where people can obtain food by foraging, farming, or pastoralism. There is also one site controlled by a local elite. We start from an equilibrium with mild stratification, reflecting the conditions of the ’Ubaid period. A climate shift toward increasing aridity reduces the productivities of sites dependent on rainfall but does not affect the productivity of the elite-controlled site where irrigation is based on river water. This lowers commoner food income and shifts population toward elite-controlled land. The declining standard of living for commoners makes it profitable for the elite to create urban workshops producing textiles and other goods, where manufacturing has aggregate increasing returns to scale. The taxation of manufacturing allows the elite to enforce monopolistic output restrictions, driving up the price of manufactured goods and driving down the wage. Organized elites may want to establish city-states based upon manufacturing even if they lack interest in public goods, because taxation can be used to enhance private elite consumption. The key tradeoff for the elite involves profit from manufacturing versus land rent from agriculture.
After an introductory section that frames some conceptual issues surrounding the emergence of city-states, most of the chapter is devoted to a chronological narrative describing the case of southern Mesopotamia. This includes sections on the pre-’Ubaid period, the ’Ubaid period, the Uruk period, and the post-Uruk period. The key puzzle is how to explain the transition from scattered villages and small towns in the ’Ubaid period to large city-states with tens of thousands of residents in the Uruk period. Following the main narrative, we review causal hypotheses on this subject proposed by archaeologists and economists. These include ideas about climate change, migration, food production, manufacturing, trade, warfare, and culture. We also offer a synthesis of our own. In our view, the prime mover was increasing aridity, which motivated migration from outlying areas toward the south. As this process unfolded, commoner living standards fell, which enabled local elites in the south to employ commoners at a lower wage. When the wage had fallen far enough, urban manufacturing became profitable. Elite taxation of urban manufacturing was probably easier than taxation of rural agriculture, and this provided the fiscal foundations for early city-states like Uruk.
This chapter constructs a theory about the origins of inequality. Our model involves a continuum of sites that have differing productivities with respect to food. All sites are initially open, and free mobility of agents across sites tends to equalize the food incomes of the agents. However, an organized group that is large enough relative to the land area of a site can establish property rights over that site and keep other agents from entering. As climate or technology improves, population densities grow, and over time the best sites become closed. This generates insider–outsider inequality, where different groups have different standards of living depending on the productivities of their sites. Eventually insiders at the best sites find it profitable to hire outsiders to work on their land, either by paying them a wage or requiring them to pay land rent. This gives elite–commoner inequality, or stratification. Class positions become hereditary. Technical progress makes commoners worse off in the long run because as regional population rises, more sites are closed. The sites that remain open are the least desirable. These predictions are consistent with archaeological evidence from southwest Asia, Europe, Polynesia, and the Channel Islands of California.
This paper synthesizes evidence for the origin and spread of the Indo-European languages from three disciplines – genomic research, archaeology, and, especially, linguistics – to reassess the validity of the Anatolian and Steppe Hypotheses. Research on ancient DNA reveals a massive migration off the steppe c. 2500 BCE, providing exceptionally strong support for the Steppe hypothesis. However, intriguing questions remain, such as why ancient Greek and Indo-Iranian populations had a smaller proportion of steppe ancestry, and Anatolian apparently had none at all. Lexical and archaeological evidence for wheels and looms provides essential clues about the early separation of Anatolian from the Indo-European community and the late entrance of Greek into the Aegean area. Evidence from the morphologies of the Indo-European languages supports these findings: the morphological patterns of the Anatolian languages show clear archaism, implying earlier separation, while the morphologies of Indo-Iranian and Greek display an array of similarities pointing to relatively late areal contact. Both the lexical and the morphological evidence, then, alongside the genomic and archaeological record, suggests that the Steppe hypothesis offers a preferable solution. Ultimately, these conclusions demonstrate the need for more dynamic models of change, including considerations of contact, stratification, and cross-disciplinary approaches.
We emphasize that the ability for a corpus to provide accurate estimates of a linguistic parameter depends on the combined influence of domain considerations (coverage bias and selection bias) and distribution considerations (corpus size). By using a series of experimental corpora on the domain of Wikipedia articles, we can demonstrate the impact of corpus size, coverage bias, selection bias, and stratification on representativeness. Empirical results show that robust sampling methods and large sample sizes can only give you a better representation of the operational domain (i.e. overcome selection bias). However, by themselves, these factors cannot help you achieve accurate quantitative-linguistic analyses for the actual domain (i.e. overcome coverage bias) Uncontrolled domain considerations can lead to unpredictable results with respect to accuracy.
We show that attending to domain considerations in corpus design involves three steps: (1) describing the domain as fully as possible; (2) operationalizing the domain; (3) sampling the texts. Describing the domain requires defining the boundaries of the domain: what texts belong within the domain and what do not? Describing the domain requires identifying important internal categories of texts that reflect qualitative variation within the domain. Domain description should be carried out systematically using a range of sources that can be evaluated for quality and triangulated. Operationalizing the domain refers to specifying the set of texts that are available for sampling; operational domains are always precisely bounded and specified. A sampling frame is an itemized list of all texts (from the operational domain) that are available for sampling. A sampling unit is the individual “object” (usually a text) that will be included in the corpus. Stratification is the process of collecting texts according to identified categories within the domain, and is usually desirable in corpus design. Proportionality refers to the relative sizes of strata within the sample. Strata can be proportional or equal-sized. Sampling methods can be broadly categorized as random and nonrandom.