The primary focus of this article is to capture heterogeneous treatment effects measured by the conditional average treatment effect. A model averaging estimation scheme is proposed with multiple candidate linear regression models under heteroskedastic errors, and the properties of this scheme are explored analytically. First, it is shown that our proposal is asymptotically optimal in the sense of achieving the lowest possible squared error. Second, the convergence of the weights determined by our proposal is provided when at least one of the candidate models is correctly specified. Simulation results in comparison with several related existing methods favor our proposed method. The method is applied to a dataset from a labor skills training program.

I argue that the epistemic aim of scientific theorizing (EAST) is producing theories with the highest possible number and degree of theoretical virtues (call this “TV-EAST”). I trace TV-EAST’s logical empiricist origins and discuss its close connections to Kuhn’s and Laudan’s problem-solving accounts of the aim of science. Despite TV-EAST’s antirealist roots, I argue that if one adopts the realist view that EAST is finding true theories, one should also endorse TV-EAST. I then defend TV-EAST by showing that it addresses the challenges raised against using the “aim of science” metaphor and offers significant advantages over the realist account.

A 13,500-year-old record from Langohr Wetland in the Gallatin Range of southwestern Montana offers new insights into the vegetation and fire history at middle elevations within the Greater Yellowstone Ecosystem. Pollen data suggest that following deglaciation, a tundra–steppe established until warmer and wetter conditions than before could support Picea parkland. The development of an open, predominantly Pinus mixed-conifer forest from ca. 9300–7000 cal yr BP suggests warming summer temperatures led to an increase in forest cover and fire activity; the increase in tree abundance supported infrequent, stand-replacing fires approximately every 600 years. Picea and Pseudotsuga increased their presence at ca. 7000 cal yr BP, and the mixed-conifer forest became denser during the Mid- and Late Holocene, suggesting summers became cooler and wetter. The additional fuel load led to increased fire activity, with stand-replacing fires occurring approximately every 350 years in the Late Holocene. The forest surrounding Langohr Wetland experienced less change in vegetation composition and structure and fewer fire episodes than other low- and high-elevation sites in the Greater Yellowstone Ecosystem. The stability of this forested ecosystem over thousands of years is likely a result of its cool mesic mid-elevation setting, limiting the frequency of intense fire episodes.

Detecting cracks in underwater dams is crucial for ensuring the quality and safety of the dam. However, underwater dam cracks are easily obscured by aquatic plants. Traditional single-view visual inspection methods cannot effectively extract the feature information of the occluded cracks, while multi-view crack images can extract the occluded target features through feature fusion. At the same time, underwater turbulence leads to nonuniform diffusion of suspended sediments, resulting in nonuniform flooding of image feature noise from multiple viewpoints affecting the fusion effect. To address these issues, this paper proposes a multi-view fusion network (MVFD-Net) for crack detection in occluded underwater dams. First, we propose a feature reconstruction interaction encoder (FRI-Encoder), which interacts the multi-scale local features extracted by the convolutional neural network with the global features extracted by the transformer encoder and performs the feature reconstruction at the end of the encoder to enhance the feature extraction capability and at the same time in order to suppress the interference of the nonuniform scattering noise. Subsequently, a multi-scale gated adaptive fusion module is introduced between the encoder and the decoder for feature gated fusion, which further complements and recovers the noise flooding detail information. Additionally, this paper designs a multi-view feature fusion module to fuse multi-view image features to restore the occluded crack features and achieve the detection of occluded cracks. Through extensive experimental evaluations, the MVFD-Net algorithm achieves excellent performance when compared with current mainstream algorithms.

In this article, we consider the relationship between conceptual blending, creativity and morphological change, within the framework of Diachronic Construction Morphology (DCxM; Norde & Trousdale 2023). In particular, we suggest that a refinement to models of creativity in the literature might help to account better for different types of morphological change (Norde & Trousdale 2024). This is achieved via a contrastive analysis of two different sets of changes: (a) the creation of English libfixes (Zwicky 2010; Norde & Sippach 2019), e.g. snowmaggedon and spooktacular, and (b) the development of Dutch pseudoparticiples (Norde & Trousdale 2024), e.g. bebrild ‘bespectacled’ and ontstekkerd ‘with all plugs removed’.

Semantic extensibility captures the semantic side of productivity. It is the likelihood that a given sense of a linguistic expression will support extension to new senses. Even though linguistic expressions are naturally polysemous, semantic extensibility is constrained. In previous literature, it has been argued that semantic extensions are motivated by mostly one-directional conceptual operations such as metaphor and metonymy, and that in any polysemous expression only one or a few so-called ‘sanctioning’ senses have privileged status in supporting new extensions. One factor believed to determine sanctioning status is high frequency. Drawing on three case studies from the history of English, involving change in the adjective awful, the preposition and adverb about and the multifunctional item so, this article provides diachronic evidence from semantic loss to support this view. On the one hand, it is shown that when old sanctioning senses go into decline, this also impacts the senses derived from them, underscoring the motivational relations that tie extended senses to sanctioning senses. On the other hand, what typically initiates a decline in a sanctioning sense is a frequency increase elsewhere in the polysemy network coincident with the emergence of a new sanctioning sense, underscoring the role of frequency in determining sanctioning status and the directionality of sanctioning relations.

In this paper, we investigate the relation between head movement and the synthesis-periphrasis distinction in the verbal domain. We use the term synthesis to refer to verbal expressions in which the lexical verb bears all the verbal inflection in a clause (e.g. rode in English). In contrast, a periphrastic verbal expression additionally contains an auxiliary verb (specifically, be or have), and verbal inflection is distributed between the lexical verb and the auxiliary (e.g. had ridden). We argue for two crosslinguistic generalizations: AfTonomy and *V-Aux. According to AfTonomy, affixal Ts vary as to whether they are in a head movement relation with a verb. *V-Aux states that in periphrasis, the lexical verb and the auxiliary cannot be related by head movement. Existing analyses of periphrasis can account for one or the other generalization, but not for both. We further argue that this tension between the two generalizations is resolved if we adopt the hypothesis that both head movement and periphrasis are tied to selection. More specifically, we propose that head movement is parasitic on a selectional relation (following Svenonius 1994, Julien 2002, Matushansky 2006, Pietraszko 2017, Preminger 2019) and that auxiliaries are merged as specifiers selected by functional heads such as T (Pietraszko 2017, 2023).