Human astroviruses are a common cause of viral gastroenteritis and are often underdiagnosed. While infections are typically mild or asymptomatic in immunocompetent hosts, astrovirus can cause prolonged and severe disease in immunocompromised individuals. Here, we conducted a case-control study to evaluate the clinical presentation of astrovirus infections in paediatric oncology patients. Our findings were compared to two groups: (1) norovirus infections in the same immunocompromised cohort, and (2) a cohort of immunocompetent children with and without diarrheal symptoms. Astrovirus was detected in 9.8% of immunocompromised patients, with prolonged shedding seen in multiple cases. Astrovirus infection was associated with an increased odds of diarrhoea, although this association weakened when adjusting for co-infections. In contrast, norovirus was not significantly associated with diarrhoea in immunocompromised patients, despite prolonged shedding in 24% of the cohort. High rates of co-infection with adenovirus and Clostridium difficile may have influenced symptom patterns. In the immunocompetent cohort, astrovirus was not associated with diarrhoea, while norovirus showed a strong association with symptoms. These findings indicate that astrovirus infections are more likely to cause diarrhoea in immunocompromised paediatric patients, while often asymptomatic in immunocompetent children. Norovirus showed the opposite trend, highlighting distinct roles of host immune status in shaping clinical outcomes. These findings highlight the importance of considering astrovirus as a potential contributor to gastrointestinal symptoms in immunocompromised children and call for broader diagnostic testing and further research on viral co-infections and persistence.
Microplastic (particles <5 mm) is an emerging environmental concern that threatens aquatic ecosystems worldwide. While extensive research has documented the ubiquity of microplastic in marine and coastal environments and its assimilation by organisms at all trophic levels, comparatively little is known about microplastic occurrence in rural riverine ecosystems. Even less information exists for salmon-bearing streams, where microplastic pollution may hinder salmonid conservation and recovery efforts. We examined the presence and concentration of microplastic in Scott Creek, a small coastal California (USA) watershed with minimal urban development. Our study quantified suspended microplastic in surface waters and in the gastrointestinal (GI) tracts of juvenile Steelhead Trout (Oncorhynchus mykiss). Microplastic was detected in 93 % of water samples, indicating that Scott Creek routinely transports and cycles microplastic. Concentrations were higher in late summer than in spring, although monthly spatial patterns were largely consistent among sites. In juvenile steelhead, 60.6 % of GI tracts contained one or more types of microplastic. For both surface waters and juvenile steelhead, microplastic was predominantly small (<5 mm) dark blue, black, and transparent fiber-type particles, with fragments, shards and foams encountered less frequently. These findings suggest that fish ingest microplastic at low frequencies, or that ingested particles may pass rapidly through their digestive systems. This study provides one of the first assessments of microplastic in a minimally urbanized, salmon-bearing watershed. Our results serve as a baseline for evaluating the ecological implications of microplastic pollution in small coastal creeks and its potential to influence native salmonid populations. Data Availability The surface water and steelhead microplastic datasets generated and analyzed during the current study are publicly available via Zenodo (DOI: 10.5281/zenodo.18038857).
Comprehenders in many of the world's languages exhibit a preference or a greater ease in comprehending transitive relative clauses (RCs) when associating the dislocated head with a subject position. Some theories relate this preference to an early prediction that an animate head will serve as a subject. We present a picture selection experiment with eye-tracking investigating the role of such predictions in comprehending transitive RCs in Santiago Laxopa Zapotec, an Oto-Manguean language of southern Mexico where RCs are ambiguous unless they contain a resumptive pronoun. Patterns of offline choices and incremental looking suggest that Santiago Laxopa Zapotec comprehenders avoid forming predictive interpretations of the RC head, and do not take its animacy into account in early processing. Instead, comprehenders exhibit a later, animacy-sensitive bias to interpret the RC-internal co-argument as a subject. Overall, we take this pattern as evidence that a comprehender's structural predictions must be somehow dependent on experience-based tuning, while more universal pressures like similarity-based interference remain fixed. The lingering question for theories of cross-linguistic processing is how much of our predictive mechanism is tunable: do we tune just the distribution of expected structures which directs predictions, or also the practice of deploying predictions itself? We discuss how either of these approaches might explain the pattern we observe in Santiago Laxopa Zapotec, and highlight that an answer to this question will depend on continued investigations across a diverse sample of the world's languages.
This study analyzes how changes in forage species distribution affected Coastal Pelagic Species (CPS) vessel participation and target decisions in the U.S. West Coast fishery over the 2013–2017 period. We develop discrete choice models for the choice of species targeted: Pacific sardine (Sardinops sagax), market squid (Doryteuthis opalescens), Northern anchovy (Engraulis mordax), Chub (Scomber japonicus) and Jack (Trachurus symmetricus) mackerels or other Non-CPS species, and landing port during a specific day. We estimate separate nested logit models by fleet segments, which were defined previously using cluster analysis on vessel attributes such as fished area, average annual revenue, CPS diversification, and degree of reliance on CPS. An environmentally informed species distribution model (SDM) is used as a proxy for expected availability of forage species. We find that harvesters demonstrate flexibility in their fishing strategies in response to environmental and economic conditions. The study suggests that while some decisions are state-dependent, harvesters still have the capacity for adaptation. These insights are crucial for understanding the resilience of fisheries in the face of environmental variability and for informing management strategies to support sustainable fishing into the future.
Many of the oceans' top predatory fishes at low to mid latitudes face an uncertain future as their vulnerable larvae deal with higher environmental temperature and reduced productivity associated with climate change. However, ocean ecosystem models that predict a general decline of zooplankton prey with warming and stratification hardly ever account for complexities in pelagic food webs that might make them resilient in providing food resources for larvae. We illustrate such complexities in comparing feeding interactions of larval Southern Bluefin Tuna (SBT) between two studies conducted 35 y apart in the same spawning region off northwest Australia. In the first (1987), SBT larvae fed and grew at low rates demonstrably limited by zooplankton prey. In the second (2022), feeding and growth were significantly higher despite substantially warmer conditions. The difference reflects a realignment in larval feeding preference from copepods to appendicularians, which allows a more direct and efficient energy transfer pathway from the microbially dominated food web base to higher-level consumers. These findings reset thinking on bluefin larvae feeding preferences, demonstrate high growth on an appendicularian diet up to 30 °C, and align with predictions of appendicularians being an environmentally selected zooplankton category in warming oligotrophic waters.
In this article, we further develop the Riemann–Hilbert formalism introduced in our earlier work [Gharakhloo and Its, SIGMA 16 (2020), 100] for the asymptotic analysis of Toeplitz+Hankel determinants with distinct Toeplitz and Hankel symbols. In that work, we showed that the associated Riemann–Hilbert problem can be analyzed by the Deift–Zhou nonlinear steepest descent method under a special restriction on the winding numbers of the symbols. This restriction excludes several natural cases, including the zero–winding configuration for both ϕ and w. The main goal of the present paper is to extend the asymptotic analysis of Toeplitz+Hankel determinants to a broader class of winding–number configurations. As an application, we study the case associated with the Ising model on the zig–zag layered half–plane with critical boundary magnetic field, for which the winding numbers of the Toeplitz and Hankel symbols are 0 and −1, respectively. In this setting, we compute the asymptotics of the norms of the corresponding system of orthogonal polynomials.
Like many of Earth's subtropical open ecosystems, the African savanna originated in the Miocene Epoch (23.0 to 5.3 Ma), one of the best historical analogs for future climate states. The first C4 grass, C3 tree, and shrub savanna developed in the subtropics after ~10 Ma in northwest Africa, but the terrestrial sedimentary record of the region is not well preserved, making it difficult to determine when, how, and why the African landscape opened. Here, we leverage plant-wax biomarkers extracted from the marine sedimentary archive to document the origination and history of open ecosystems through Miocene northwest Africa. We show that a C3 grass-rich savanna with no modern analog replaced closed woodlands and forests during the middle Miocene (~15 to 14 Ma), a period of global cooling and aridification. This nonanalog ecosystem transitioned into the C4 savanna in stages in the late Miocene (most rapidly between 7.4 to 6.4 Ma) as global temperatures cooled and aridity increased, roughly coincident with several C4 expansions in other subtropical regions. Our new vegetation history, put in the context of other records, links initial ecosystem opening and C4 expansion to periods of global cooling and drying. It is consistent with a nonlinear system of feedbacks between climate, consumers (herbivory and fire), and plant-trait interactions that allows small changes in one parameter to have dramatic effects on regional vegetation structure and composition. The geologic record indicates that the response of subtropical open ecosystems to future climate perturbations will depend on the nature and strength of these feedbacks.
Orthoflavivirus RNA genomes resist host 5'-3' exoribonucleases to produce subgenomic flaviviral RNAs (sfRNAs). This resistance is conferred by exoribonuclease-resistant RNA (xrRNA) structures within the viral 3' untranslated region that often occur in tandem, and whose function can be coupled. In dengue virus serotype 2 (DENV2), this coupling results in changing patterns of sfRNA identity and abundance associated with the ability of the virus to adapt to host vs. vector infections. The physical basis of this coupling was unknown. Using a combination of virology, biochemistry, bioinformatics, structural biology, and biophysics, we explored the structural and sequence determinants of tandem xrRNA coupling in DENV2. We discovered that the spatial proximity, order, and structural integrity of the tandem xrRNAs are all important for coupling. Furthermore, an unpaired A-rich linker that lies between the two xrRNAs is essential in stabilizing a specific structure that correlates to coupling. This A-rich sequence likely forms tertiary contacts with an adjacent stem-loop structure to form a physical bridge between the two xrRNAs, a finding that is supported by a mid-resolution cryo-electron microscopy (cryo-EM) map of the DENV2 tandem xrRNAs. Disruption of the structure of this bridge by mutation changes the relative orientation or spacing between the tandem xrRNAs, which is correlated to their functional coupling. These findings help provide an explanation for the coupling between tandem xrRNAs, suggesting a new mechanistic hypothesis in which the two tandem xrRNAs can simultaneously encounter Xrn1.IMPORTANCEDengue virus (DENV) generates non-coding subgenomic flaviviral RNAs (sfRNAs) that affect several cellular pathways and are important for successful infection. These sfRNAs are formed by structured RNA elements in the viral genome called exoribonuclease-resistant RNAs (xrRNAs), which fold into a distinct three-dimensional topology to block degradation by host cell exoribonucleases and often occur in tandem. Specific patterns of sfRNAs made during infection are important for host vs. vector fitness, and in DENV2, this pattern depends on functional coupling between tandem xrRNAs. However, the source of this functional coupling was unknown. We determined that an unpaired A-rich linker between the tandem xrRNAs is necessary for creating a structural bridge between the tandem xrRNAs. This bridge appears to favor a specific orientation between the tandem xrRNAs that is correlated to coupling and therefore to the patterns and relative abundance of sfRNAs produced during infection.
BACKGROUND: The accuracy of relative stopping power (RSP) is a critical aspect for safe treatment planning in proton therapy. Dual-energy CT (DECT) has the ability to estimate RSP more accurately than conventional single-energy CT (SECT) due to its improved material separation. RSP accuracy is commonly determined in homogeneous phantom material as it can be more challenging to determine in heterogeneous biological tissues. Proton CT (pCT) is a modality that directly determines RSP and can be used as a comparative benchmark for evaluating the RSP accuracy of DECT and SECT derived values across homogeneous and heterogeneous material. PURPOSE: In this study, DECT was compared to SECT in both homogeneous phantom inserts of known RSP and heterogeneous tissue samples of unknown RSP using pCT as a quantitative reference. The purpose of this study was to assess the ability of DECT to improve RSP estimation over SECT in unknown RSP of heterogeneous tissues. METHODS: A variety of homogeneous phantom inserts were scanned using pCT, DECT, and SECT. The estimated RSP from each imaging modality was compared to the RSP of each insert directly measured using a multilayer ionization chamber (MLIC). Scans of heterogeneous tissue samples were also acquired using pCT, DECT, and SECT. The images from each modality were registered and a variety of tissue regions of interest were contoured. The percent difference of DECT and SECT derived RSP values compared to pCT was calculated across both homogeneous phantom and heterogeneous tissue regions and compared. RESULTS: The mean absolute percentage error for the inserts compared to the known RSP was 1.6% ± 1.6% in pCT, 1.1% ± 1.6% in DECT, and 4.6% ± 6.2% in SECT. For inserts with relative electron density greater than 0.93 and excluding true water and aluminum, DECT average percent difference compared to pCT was -0.5% ± 0.02% while in SECT it was -1.5% ± 0.07%. In biological tissue, excluding enamel, the average percent difference for DECT compared to pCT was -0.3% ± 1.1%, while for SECT the percent difference compared to pCT was 0.6% ± 3.0%. CONCLUSIONS: Fast kV-switching DECT obtained smaller RSP deviations from pCT compared to SECT in homogeneous tissue-equivalent phantom inserts. In heterogeneous tissue samples, DECT maintained improved RSP accuracy compared to SECT.
