The present study addressed the influence of lithological variability on hydrothermal alteration processes in the Çubuk region of Ankara, recognized globally for its agate occurrences. The objective was to clarify how differing host rocks, tuff and ignimbrite in Karadana, and perlitic units in Yukarıemirler, affect secondary mineral formation and alteration pathways. A combination of mineralogical (X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy) and geochemical (energy-dispersive X-ray spectroscopy, whole-rock geochemistry, δ18O–δD) methods was utilized to characterize alteration assemblages and fluid conditions. The alteration sequence progressed through five stages, beginning with unaltered volcanic rocks. In the second stage, smectite-group clays, particularly montmorillonite, were formed under mildly alkaline and low-temperature conditions (pH 7.5–9.0; T 43–50°C). This initial clay formation was followed by zeolitization along two distinct pathways: clinoptilolite crystallized (K-rich, Si/Al ~4.2) in the Karadana tuff–ignimbrite units, while heulandite formed (Ca-rich, Si/Al ~2.7) in the perlitic host rocks of Yukarıemirler. These variations are attributed to differences in host-rock composition, permeability, and hydrothermal fluid chemistry. In more advanced stages, mordenite and chabazite precipitated under progressively higher pH and temperature conditions (pH 9.5–10.0; T 70–80°C). In the final stage, opal–quartz formed due to silica supersaturation triggered by a drop in pH, despite rising temperatures (pH ~8.5–9.0; T ~250°C). The paragenetic sequence confirms that clay mineral formation preceded zeolitization in both zones. Variations in zeolite types reflect strong lithological and hydrochemical controls, as well as the origin of the hydrothermal fluids; clinoptilolite formation in Karadana is associated with Na- and K-rich supergene fluids, while Ca-rich hypogene fluids promoted heulandite precipitation in Yukarıemirler. This study presents the first detailed paragenetic model for zeolite–clay alteration in the Çubuk volcanic system and offers new insights into post-caldera hydrothermal evolution in Central Anatolia.

Gcd-graphs over the ring of integers modulo n are a natural generalization of unitary Cayley graphs. The study of these graphs has foundations in various mathematical fields, including number theory, ring theory, and representation theory. Using the theory of Ramanujan sums, it is known that these gcd-graphs have integral spectra; i.e., all their eigenvalues are integers. In this work, inspired by the analogy between number fields and function fields, we define and study gcd-graphs over polynomial rings with coefficients in finite fields. We establish some fundamental properties of these graphs, emphasizing their analogy to their counterparts over ${\mathbb {Z}}.$

In this paper, we present two corpus-based case studies which cast doubt on the postulation of a distinction between complements and modifiers in pre-head position in the English noun phrase. Based on examples such as medical student, the paper focuses on ordering patterns as an easily observable criterion, rather than more difficult or less reliable criteria such as anaphoric replacement or stress patterns. The conclusion is that the pre-head dependents treated as complements in, for example, the Cambridge Grammar of the English Language (Huddleston & Pullum et al. 2002), should rather be treated as type-dependents. This conclusion, at least as far as ordering patterns are concerned, is in line with the postulation of a “classifier” function in approaches to English noun phrases such as Feist (2009).

This editorial discusses the common practice of using normality tests as a preliminary step for choosing between parametric and non-parametric methods. The editorial argues that such pre-testing is theoretically unfounded and practically harmful, as parametric tests are robust to moderate deviations from normality, while reliance on normality tests can distort error rates and mislead researchers.

Although the relevance of the dynamic nature of teams has generated a thriving literature, contributions have originated from a variety of disciplines. This situation has hindered scholarly understanding and collaboration. To assess the state of the dynamic teams’ field in an unbiased and comprehensive way, a literature review relying upon bibliometric techniques combined with content analysis was conducted. Considering all disciplines that have examined the subject, this study aimed at defining its knowledge structure, identifying its main research lines, methods, and key theoretical framework. Results revealed eight research lines. Teams/teamwork, membership change, performance, dynamic team, and membership change were found as the motor themes. In turn, decentralised control, access control, multi-robot system, and distributed system were found as themes that are either emerging or disappearing. The latter themes, related to the engineering and computing fields, are emerging and are likely to become central and developed. Future research lines are suggested.