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Municipalities face increasingly complex challenges from climate change-driven natural hazards that threaten health, infrastructure, and livelihoods. Addressing these risks requires ambitious climate policies that drive the societal transformations advocated in climate policy literature. This study examines factors enabling local governments to adopt ambitious flood risk management. Ambitious climate adaptation policies go beyond minimum regulatory requirements to reduce climate vulnerability and enhance resilience. They facilitate their community’s ability to bounce forward after confronting system disruptions and shocks. Given the dynamic nature of climate challenges, scholars emphasize the importance of having a capacity for transformation over achieving fixed outcomes. Accordingly, this study hypothesizes that city governments with higher Transformative Governance Capacity (TGC) are more likely to implement ambitious flood management strategies. TGC is characterized by behavioural qualities such as being learning-focused, proactive, and risk-accepting. Using survey data from 386 U.S. cities, we operationalize and quantify local governments’ TGC and analyze its association with ambitious flood management practices, as proxied by participation in the Community Rating System (CRS) – a voluntary programme that incentivizes communities to exceed national flood mitigation standards. The findings support the hypothesis that greater TGC is associated with higher levels of involvement in the CRS and higher CRS scores, underscoring the importance of this distinct type of behavioural capacity in addressing escalating climate threats. 

Abstract For$$E \subset \mathbb {N}$$, a subset$$R \subset \mathbb {N}$$isE-intersectiveif for every$$A \subset E$$having positive relative density,$$R \cap (A - A) \neq \varnothing $$. We say thatRischromatically E-intersectiveif for every finite partition$$E=\bigcup _{i=1}^k E_i$$, there existsisuch that$$R\cap (E_i-E_i)\neq \varnothing $$. When$$E=\mathbb {N}$$, we recover the usual notions of intersectivity and chromatic intersectivity. We investigate to what extent the known intersectivity results hold in the relative setting when$$E = \mathbb {P}$$, the set of primes, or other sparse subsets of$$\mathbb {N}$$. Among other things, we prove the following: (1) the set of shifted Chen primes$$\mathbb {P}_{\mathrm {Chen}} + 1$$is both intersective and$$\mathbb {P}$$-intersective; (2) there exists an intersective set that is not$$\mathbb {P}$$-intersective; (3) every$$\mathbb {P}$$-intersective set is intersective; (4) there exists a chromatically$$\mathbb {P}$$-intersective set which is not intersective (and therefore not$$\mathbb {P}$$-intersective). 

Online search and brokering (OSB) is the phenomenon in which youth search for information for their immigrant families on the Internet. Few studies exist on reflecting on the past as youth conduct OSB from childhood to adolescence to young adulthood. We conducted a retrospective study using semi-structured interviews of 27 young adults (ages 19 - 24) to examine their experience and perceptions of OSB over time (primary schooling, secondary schooling, undergraduate). We found that although all the interviewees shared a common experience of being an online searcher and information broker for their immigrant families, their stories exist on various dimensions which are constantly shifting and changing over time, as ecological factors influence searching behaviors. We discuss how the results from our study can serve as future references for researchers doing work in search research and designers who are currently working on improving design tools for searching. 

Abstract Recent large-scale societal disruptions, from the COVID-19 pandemic to intensifying wildfires and weather events, reveal the importance of transforming governance systems so they can address complex, transboundary, and rapidly evolving crises. Yet current knowledge of the decision-making dynamics that yield transformative governance remains scant. Studies typically focus on the aggregate outputs of government decisions, while overlooking their micro-level underpinnings. This is a key oversight because drivers of policy change, such as learning or competition, are prosecuted by people rather than organizations. We respond to this knowledge gap by introducing a new analytical lens for understanding policymaking, aimed at uncovering how characteristics of decision-makers and the structure of their relationships affect their likelihood of effectuating transformative policy responses. This perspective emphasizes the need for a more dynamic and relational view on urban governance in the context of transformation. 

Abstract We prove three results concerning the existence of Bohr sets in threefold sumsets. More precisely, lettingGbe a countable discrete abelian group and$$\phi _1, \phi _2, \phi _3: G \to G$$be commuting endomorphisms whose images have finite indices, we show that(1)If$$A \subset G$$has positive upper Banach density and$$\phi _1 + \phi _2 + \phi _3 = 0$$, then$$\phi _1(A) + \phi _2(A) + \phi _3(A)$$contains a Bohr set. This generalizes a theorem of Bergelson and Ruzsa in$$\mathbb {Z}$$and a recent result of the first author.(2)For any partition$$G = \bigcup _{i=1}^r A_i$$, there exists an$$i \in \{1, \ldots , r\}$$such that$$\phi _1(A_i) + \phi _2(A_i) - \phi _2(A_i)$$contains a Bohr set. This generalizes a result of the second and third authors from$$\mathbb {Z}$$to countable abelian groups.(3)If$$B, C \subset G$$have positive upper Banach density and$$G = \bigcup _{i=1}^r A_i$$is a partition,$$B + C + A_i$$contains a Bohr set for some$$i \in \{1, \ldots , r\}$$. This is a strengthening of a theorem of Bergelson, Furstenberg and Weiss. All results are quantitative in the sense that the radius and rank of the Bohr set obtained depends only on the indices$$[G:\phi _j(G)]$$, the upper Banach density ofA(in (1)), or the number of sets in the given partition (in (2) and (3)). 

Substituent-dependent reactivity and selectivity in the intramolecular reactions of arynes tethered with an allene are described. With a 1,3-disubstituted allene moiety, an Alder–ene reaction of an allenic C–H bond is preferred over a [2 + 2] cycloaddition, whereas a [2 + 2] cycloaddition of the terminal π-bond of the allene is preferred with a 1,1-disubstituted allene. With a 1,1,3-trisubstituted allene-tethered aryne, an Alder–ene reaction with an allylic C–H bond is preferred over a [2 + 2] cycloaddition. 

Surveys are an important vehicle for advancing research on urban policy and governance. The introduction of online tools eased survey-based data collection, making it cheaper and easier to obtain data from key informants like local elected officials or public administrators. However, the utility of web-based survey administration may be diminishing. To investigate this dynamic and search for strategies to support survey research in urban studies, we perform a systematic review of survey research in urban policy and administration scholarship and conduct an original survey follow-up experiment. Our findings identify a clear downward trend in survey response rates that was accentuated during the COVID-19 pandemic. Results from our survey experiment show distinctly different costs per solicitation and per completed survey, depending on administration mode. These findings stimulate discussion on how scholars may continue to use surveys to generate high-quality, empirically rigorous research on urban affairs in light of recent trends. 

Abstract We present the results of an experiment investigating the generation of high-order harmonics by a femtosecond near-infrared (NIR) laser pulse in the presence of an extreme ultraviolet (XUV) field provided by a free-electron laser (FEL), a process referred to as XUV-assisted high-order harmonic generation (HHG). Our experimental findings show that the XUV field can lead to a small enhancement in the harmonic yield when the XUV and NIR pulses overlap in time, while a strong decrease of the HHG yield and a red shift of the HHG spectrum is observed when the XUV precedes the NIR pulse. The latter observations are in qualitative agreement with model calculations that consider the effect of a decreased number of neutral emitters but are at odds with the predicted effect of the correspondingly increased ionization fraction on the phase matching. Our study demonstrates the technical feasibility of XUV-assisted HHG experiments at FELs, which may provide new avenues to investigate correlation-driven electron dynamics as well as novel ways to study and control propagation effects and phase matching in HHG.