Larger spleens and greater splenic contraction during exercise may be an adaptive characteristic of Nepali Sherpa at high-altitude.

OBJECTIVES: The Sherpa ethnic group living at altitude in Nepal may have experienced natural selection in response to chronic hypoxia. We have previously shown that Sherpa in Kathmandu (1400 m) possess larger spleens and a greater apnea-induced splenic contraction compared to lowland Nepalis. This may be significant for exercise capacity at altitude as the human spleen responds to stress-induced catecholamine secretion by an immediate contraction, which results in transiently elevated hemoglobin concentration ([Hb]). METHODS: To investigate splenic contraction in response to exercise at high-altitude (4300 m; Pb = ~450 Torr), we recruited 63 acclimatized Sherpa (29F) and 14 Nepali non-Sherpa (7F). Spleen volume was measured before and after maximal exercise on a cycle ergometer by ultrasonography, along with [Hb] and oxygen saturation (SpO2). RESULTS: Resting spleen volume was larger in the Sherpa compared with Nepali non-Sherpa (237 ± 62 vs. 165 ± 34 mL, p < .001), as was the exercise-induced splenic contraction (Δspleen volume, 91 ± 40 vs. 38 ± 32 mL, p < .001). From rest to exercise, [Hb] increased (1.2 to 1.4 g.dl-1), SpO2 decreased (~9%) and calculated arterial oxygen content (CaO2) remained stable, but there were no significant differences between groups. In Sherpa, both resting spleen volume and the Δspleen volume were modest positive predictors of the change (Δ) in [Hb] and CaO2 with exercise (p-values from .026 to .037 and R2 values from 0.059 to 0.067 for the predictor variable). CONCLUSIONS: Larger spleens and greater splenic contraction may be an adaptive characteristic of Nepali Sherpa to increase CaO2 during exercise at altitude, but the direct link between spleen size/function and hypoxia tolerance remains unclear.

Differential splenic responses to hyperoxic breathing at high altitude in Sherpa and lowlanders.

The human spleen contracts in response to stress-induced catecholamine secretion, resulting in a temporary rise in haemoglobin concentration ([Hb]). Recent findings highlighted enhanced splenic response to exercise at high altitude in Sherpa, possibly due to a blunted splenic response to hypoxia. To explore the potential blunted splenic contraction in Sherpas at high altitude, we examined changes in spleen volume during hyperoxic breathing, comparing acclimatized Sherpa with acclimatized individuals of lowland ancestry. Our study included 14 non-Sherpa (7 female) residing at altitude for a mean continuous duration of 3 months and 46 Sherpa (24 female) with an average of 4 years altitude exposure. Participants underwent a hyperoxic breathing test at altitude (4300 m; barrometric pressure = âˆ¼430 torr; P O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$  = âˆ¼90 torr). Throughout the test, we measured spleen volume using ultrasonography and monitored oxygen saturation ( S p O 2 ${S_{{\mathrm{p}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ). During rest, Sherpa exhibited larger spleens (226 ± 70 mL) compared to non-Sherpa (165 ± 34 mL; P < 0.001; effect size (ES) = 0.95, 95% CI: 0.3-1.6). In response to hyperoxia, non-Sherpa demonstrated 22 ± 12% increase in spleen size (35 ± 17 mL, 95% CI: 20.7-48.9; P < 0.001; ES = 1.8, 95% CI: 0.93-2.66), while spleen size remained unchanged in Sherpa (-2 ± 13 mL, 95% CI: -2.4 to 7.3; P = 0.640; ES = 0.18, 95% CI: -0.10 to 0.47). Our findings suggest that Sherpa and non-Sherpas of lowland ancestry exhibit distinct variations in spleen volume during hyperoxia at high altitude, potentially indicating two distinct splenic functions. In Sherpa, this phenomenon may signify a diminished splenic response to altitude-related hypoxia at rest, potentially contributing to enhanced splenic contractions during physical stress. Conversely, non-Sherpa experienced a transient increase in spleen size during hyperoxia, indicating an active tonic contraction, which may influence early altitude acclimatization in lowlanders by raising [Hb].

Effective interactive engagement strategies for MOOC forum discussion: A self-efficacy perspective.

This mixed methods sequential explanatory study identified and explained the features of engagement strategies for MOOC forum discussion that help low-achieving students make significant progress. Triangulated data were collected from MOOC learners' (n = 335) scores in two reading assessments, their posts to the embedded online discussion forum, and their self-reflection learning journals. Based on learning progress between pre- and post-assessment tasks, MOOC learners are divided into three groups: 1) little, 2) moderate, and 3) significant progress. According to a statistical analysis of the quantified posts, surprisingly, the low-scoring students from the pre-test who demonstrated significant progress later engaged in significantly fewer peer-peer and peer-teacher interactions in the online discussion forum. Guided by self-efficacy literature, the reflective journals of these learners suggested that 1) learner-content interactions may help them advance learning and obtain new information and linguistic knowledge from the peer-made learning materials in the discussion forum; 2) they did not share and exchange ideas and answers with their peers. Instead, they prefer learning from others' discussions and wish to get quick feedback and suggestions on their contributions to the discussion forum; and 3) peer-peer and peer-teacher interactions were proposed as two solutions to regulate their online learning experience as they lack self-discipline and time-management skills. Implications include teachers' continuous support to encourage low-achieving students to learn peer-generated content and quick feedback on their contributions to the discussion forum.

The effect of background elements of pictures on the visual attention among ASD children with intellectual disabilities, children with intellectual disabilities and typical development: Evidence from eye-tracking and fMRI.

Traditional picture books for children come with colourful images and a multitude of elements to attract attention and increase the reading interest of typical-developing (TD) children. However, children with Autism Spectrum Disorder (ASD) are less capable of filtering out unimportant elements in pictures and focusing on social items (e.g., human faces). This study proposed that the removal of background and less important elements in the pictures of children's storybooks could facilitate better attention and enhance children with ASD's focus on the main object and thus the intended meaning of the storybook. We adopted pictures from a well-known children's book and modified them by removing the inessential background elements. Then, ASD children with intellectual disabilities (ASD+ID) (n = 40), children with ID (n = 38) and TD (n = 40) were asked to view the original and modified pictures in an eye-tracking experiment, respectively. Additionally, brain activation of ASD+ID participants (n = 10) was recorded as they were viewing those pictures in an fMRI scan. Eye-tracking found that ASD+ID children viewed the modified pictures with significantly longer average fixations, fewer fixations, fewer saccades, and higher fixation/saccade duration ratio. Contrary to the original pictures, no significant differences were found among ASD+ID, ID only and TD. Especially, ASD+ID group showed highly similar visual patterns to the TD participants when viewing the modified pictures and particularly focusing on the main character in the pictures. Additional fMRI evidence on ASD+ID group also revealed that modified pictures were associated with enhanced activation in bilateral fusiform gyri as compared to those from original pictures, which might suggest increased visual attention. Theoretical and practical implications were discussed in light of our findings.

Insights into the genetic histories and lifeways of Machu Picchu's occupants.

Machu Picchu originally functioned as a palace within the estate of the Inca emperor Pachacuti between ~1420 and 1532 CE. Before this study, little was known about the people who lived and died there, where they came from or how they were related to the inhabitants of the Inca capital of Cusco. We generated genome-wide data for 34 individuals buried at Machu Picchu who are believed to have been retainers or attendants assigned to serve the Inca royal family, as well as 34 individuals from Cusco for comparative purposes. When the ancient DNA results are contextualized using historical and archaeological data, we conclude that the retainer population at Machu Picchu was highly heterogeneous with individuals exhibiting genetic ancestries associated with groups from throughout the Inca Empire and Amazonia. The results suggest a diverse retainer community at Machu Picchu in which people of different genetic backgrounds lived, reproduced, and were interred together.

How education level influences internet security knowledge, behaviour, and attitude: a comparison among undergraduates, postgraduates and working graduates.

During the pandemic, the prevailing online learning has brought tremendous benefits to the education field. However, it has also become a target for cybercriminals. Cybersecurity awareness (CSA) or Internet security awareness in the education sector turns out to be critical to mitigating cybersecurity risks. However, previous research indicated that using education level alone to judge CSA level received inconsistent results. This study postulated Social Educational Level (SEL) as a moderator with an extended Knowledge-Attitude-Behaviour model, used students' year level as a proxy for the impact of education level, and used work exposure for the influence of social education level, to compare CSA among undergraduates, postgraduates and working graduates. The participants in the study were divided into six groups, namely year 1 university students, year 2-3university students, final-year students, postgraduate students, young working graduates, and experienced working graduates. The Human Aspects of Information Security Questionnaire was used to conduct a large-scale survey. The multivariate regression model analysis showed significant differences among the knowledge, attitude and behaviour dimensions across groups with different conditions of year-level and work exposure. However, it was found that SEL played a more significant role than an individual's education level. The study suggested that a greater endeavour be committed to educating the public at large together with individuals, institutes, corporate and governments to improve the national CSA level.

Development and validation of a PLE scale from academic administrative perspective (PLES-AA) in tertiary education: A pilot study in China.

The study aims to construct and validate a rubric to assess the effectiveness of PLEs from an academic administrative perspective (PLER-AA) in tertiary education in China. A qualitative-quantitative sequential mixed-method design was used for the scale validation. A total of 206 teachers and administrative staff participated in the Confirmative Factor Analysis (CFA), which supported the 4-dimensional scale, with policy (n = 4), program design (n = 4), curriculum/instruction (n = 4), and capacity (n = 4). Meanwhile, another 189 teachers and administrative staff participated in the current sequence of PLE applications in higher education surveys, revealing a developing phase in China. Consequently, the rubric can be used as a benchmark that provides insight to educators and administrators in developing PLEs in tertiary education in China and worldwide.