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Seabird strandings on the Brazilian coast: What influences spatial and temporal patterns?
Seabirds exhibit physiological adaptations that allow them to forage in the marine environment and undertake long-distance migrations during non-reproductive periods. As a result, they face various natural and anthropogenic pressures, which can lead to extreme fatigue and even death. Stranded bodies that float in the sea can wash ashore, providing valuable ecological information. This study aimed to analyze seabird strandings along the south and southeast coasts of Brazil between 2016 and 2019, focusing on spatiotemporal and potential environmental and anthropogenic influences. Using data from the Santos Basin Beach Monitoring Project, we calculated ecological indices of abundance, richness, and diversity for the entire seabird community and separately by migratory behavior (resident, southern migratory, northern migratory). Statistical modeling revealed a strong decreasing trend in strandings from south to north, with higher events on the southern coast (Santa Catarina and Paraná) and lower on the southeast coast (São Paulo). Resident species and northern migratory species showed peak strandings in spring, while southern migratory peaked in winter. These spatial and temporal patterns reflected birds’ home ranges, reproductive cycles, and migratory behaviors. Environmental variables influenced strandings differently depending on species migration behavior and ecological indices, highlighting the role of oceanographic processes in carcass drift and the impact of climatic events on species mortality. This study is the first to demonstrate a spatiotemporal pattern of seabird strandings on the Brazilian coast, providing valuable insights into seabird dynamics in the Santos Basin and offering important data for conservation efforts.
Material composition and constitutive model development of red mud-based filler for highway tunnel invert filling applications: A comprehensive study
To address the global environmental challenges posed by red mud waste, this paper proposes utilizing red mud as a filling material for highway tunnel inverts. It is imperative to thoroughly investigate the theoretical foundation of red mud-based filling (RMBF) materials for this application. This study explores the optimal ratio of RMBF and, drawing on the results of triaxial compression tests in conjunction with soil structural parameters and Duncan-Chang theory, proposes and defines for the first time the strengthening parameter (Sp) of RMBF to derive its constitutive model. The test data were systematically compared and analyzed with the results of theoretical calculations. The findings indicate that RMBF, which is composed of red mud, cement, steel slag, slaked lime, EDTA-2Na, water and curing agent mixed in a specific proportion, can meet the strength requirements. When used for filling the invert of a highway tunnel, 1.068 tons of red mud can be recycled from 1 cubic meter of RMBF. The stress-strain curve of the RMBF exhibits an evident peak, indicating strain softening characteristics, while the strengthening stress-strain curve clearly demonstrates strain hardening characteristics. The discrepancy between the stress-strain curve predicted by the RMBF model considering Sp and the actual test curve is within 10%, confirming the model’s rationality and applicability.
Handy divisions: Hand-specific specialization of prehensile control in bimanual tasks
When hammering a nail, why do right-handers wield the hammer in the right hand? The complementary dominance theory suggests a somewhat surprising answer. The two hands are specialized for different types of tasks: the dominant for manipulating objects, and the non-dominant for stabilizing objects. Right-handers wield the moving object with their right hand to leverage the skills of both hands. Functional specialization in hand use is often illustrated using examples of object manipulation. However, the complementary dominance theory is supported by wrist kinematics rather than object manipulation data. Therefore, our goal was to determine whether this theory extends to object manipulation. We hypothesized that hand-specific differences will be evident in the kinematics of hand-held objects and in the control of grip forces in right-handed individuals. Right-handed participants held two instrumented objects that were coupled by a spring. They moved one object while stabilizing the other object in various bimanual tasks. They performed motions of varying difficulty by tracking predictable or unpredictable targets. The two hands switched roles (stabilization vs movement) in various experimental blocks. The changing spring length perturbed both objects. We quantified the movement performance by measuring the objects’ positions, and grip force control by measuring grip-load coupling in the moving hand and mean grip force in the stabilizing hand. The right hand produced more accurate object movement, along with stronger grip-load coupling, indicating superior predictive control of the right hand. In contrast, the left hand stabilized the object better and exerted a higher grip force, indicating superior impedance control of the left hand. Task difficulty had a weak effect on grip-load coupling during object movement and no effect on mean grip force during object stabilization. These behavioral results demonstrate that complementary dominance extends to object manipulation, though the weak effect of task difficulty on grip characteristics warrants further investigation. Neurophysiological investigations can now examine the hemisphere-specific neural mechanisms underlying these behavioral differences.
Genotypic drug resistance and transmission clusters of Mycobacterium tuberculosis isolates among Ethiopian returnees from Saudi Arabia
Background Human migration significantly contributes to the global spread of infectious diseases. In recent years, Ethiopia has experienced an increased influx of returnees from the Kingdom of Saudi Arabia. These migrants were often held in densely populated and inadequately ventilated detention centers and faced a heightened risk of tuberculosis transmission. This study investigates the genotypic drug resistance and transmission clusters of M. tuberculosis among returnees from various detention centers in the Kingdom of Saudi Arabia. Whole genome sequencing (WGS) is employed to characterize the genotypic drug resistance patterns and transmission clusters of M. tuberculosis isolates in presumptive TB cases. Methodology Following symptom screening for presumptive TB, sputum samples were collected from 161 Xpert MTB/RIF-confirmed returnees between August and December 2022. The samples were further cultured on Lowenstein-Jensen media, with 66.5% (107/161) yielding positive results. The M. tuberculosis strains were classified, and genotypic drug susceptibility was predicted. Transmission clusters were identified using a distance threshold of 12 single nucleotide polymorphisms (SNPs). Results Among the 88 isolates, Lineage 4 was the most prevalent, representing 65.9% of M. tuberculosis cases among returnees. Sub-lineage 4.2.2.2 was the most dominant within this group, comprising 33% (29/88) of the isolates. Among the isolates, 40 gene mutations conferring resistance to first- and second-line anti-TB drugs were identified. Sixteen transmission clusters were identified, suggesting possible transmission events and a likely origin within the detention centers of the Kingdom of Saudi Arabia (KSA). The proportion of MDR-TB among newly diagnosed cases was 2.3% (2/88). Conclusion The clustering patterns of M. tuberculosis strain among KSA returnees possibly suggest increased transmission rates in congregate settings. Most importantly, the identified prevalence of MDR-TB, particularly among newly diagnosed TB cases, underscores the need to strengthen robust screening practices for returning migrants before they reintegrate into the community to curb TB/DR-TB transmission.