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IntroductionThe Systems Thinking Accelerator (SYSTAC) is a community to engage, connect and collaborate to elevate the field of systems thinking with a focus on low- and middle-income countries, highlighting the need to identify existing capacities within research and at the practice level. The study aimed to explore if there is a perceived need for and benefit from the application of Systems Thinking tools for analysis and diagnosis of problem-solving within Healthcare in the Region of the Americas in 2021 and the existing capabilities.MethodsThe identification and deconstruction of the needs, demands, and opportunities regarding systems thinking in the Americas were approached by: (i) adapting the tools and Systems Thinking definition to reflect regional nuances, (ii) identifying stakeholder exercise, (iii) needs assessment survey distribution, (iv) stakeholder mapping analysis, (v) workshop. More information on the adaptation and execution of each tool can be found below.Results123 stakeholders were identified, of which 40 participated in the needs assessment survey. 72% of respondents indicated little knowledge of the tools and approaches of systems thinking but a high interest in developing them, as stated by 87% of respondents. Qualitative tools were most frequently used, such as brainstorming, problem trees, and stakeholder mapping. Systems thinking is mainly used when conducting research, implementing, and evaluating projects. A clear need and want for training and developing capacities in health systems thinking were identified. However, in practice, systems thinking faces challenges like resistance to change and to the transformation of health processes, barriers at the institutional level, and other administrative disincentives that hinder its application, being institutional transparency, political will, and the articulation of the actors the main challenges.DiscussionStrengthening and building personal and institutional capacities in systems thinking theory and practice requires overcoming challenges such as lack of transparency and inter-institutional cooperation, the low political will to implement it, and difficult stakeholders' integration. As a first step, it is crucial to understand further the stakeholder network and the capacity needs of the region, gain buy-in from strategic players to establish the use of system thinking as a priority, and develop a roadmap.

Gamete size variation between the sexes is central to the concept of sex roles, however, to what extent gamete size variation within the sexes relates to sex role variation remains unclear. Comparative and theoretical studies suggest that, when clutch size is invariable, polyandry is linked to a reduction of egg size, while increased female-female competition for mates favors early breeding when females cannot monopolize multiple males. To understand whether and how breeding phenology, egg size, and mating behavior are related at the individual level, we studied the reproductive histories of 424 snowy plover females observed in the wild over a 15-year period. Egg size, but not polyandry, were highly repeatable for individual females. Consistent with theoretical predictions, we found that polyandrous females were the earliest breeders and that early clutches contained smaller eggs than clutches initiated later. Neither egg size nor mating behavior showed clear signs of an age-related deterioration, on the contrary, prior experience acquired either through age or local recruitment enabled females to nest early. Taken together, these results suggest that gamete size variation is not linked to mating behavior at the individual level, and, consequently, the adaptive potential of such variation appears to be limited., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE).)

Objectives: Different studies have reported the association between perceived stress and unhealthy diet choices. We aimed to determine whether there is a relationship between perceived stress and fat intake among undergraduate medical students., Methods/principal Findings: A cross-sectional study was performed including first-year medical students. The outcome of interest was the self-report of fat intake assessed using the Block Screening Questionnaire for Fat Intake (high vs. low intake), whereas the exposure was perceived stress (low/normal vs. high levels). The prevalence of high fat intake was estimated and the association of interest was determined using prevalence ratios (PR) and 95% confidence intervals (95%CI). Models were created utilizing Poisson regression with robust standard errors. Data from 523 students were analyzed, 52.0% female, mean age 19.0 (SD 1.7) years. The prevalence of high fat intake was 42.4% (CI: 38.2%-46.7%). In multivariate model and compared with those with lowest levels of stress, those in the middle (PR = 1.59; 95%CI: 1.20-2.12) and highest (PR = 1.92; 95%CI: 1.46-2.53) categories of perceived stress had greater prevalence of fat intake. Gender was an effect modifier of this association (p = 0.008)., Conclusions: Greater levels of perceived stress were associated with higher fat intake, and this association was stronger among males. More than 40% of students reported having high fat consumption. Our results suggest the need to implement strategies that promote decreased fat intake.

The association between coronary artery calcification (CAC) and coronary artery disease is well established. The objectives of this article are to define the cross-sectional anatomy of the coronary arteries and to demonstrate the prevalence of CAC as seen on routine computed tomography (CT) of the thorax. A CT scan of a cadaver heart was performed in normal anatomic position. Additionally, a retrospective analysis of 103 consecutive thoracic scans was done by three experienced radiologists. The cross-sectional anatomy of the coronary arteries is described based on both these studies, and the prevalence of coronary calcification from the retrospective review was determined. The left anterior descending was the most commonly calcified artery (43% of all patients) followed in order by the left coronary (37%), circumflex (33%), and right coronary (20%). Seventy-nine percent of patients older than age 65 demonstrated coronary calcification on CT. This prevalence approaches that of reported autopsy series. Knowledge and understanding of the cross-sectional anatomy of coronary arteries is essential for detection of coronary artery calcification. We recommend that the presence of CAC should be reported on all thoracic CT scans because coronary calcification may signal unsuspected coronary artery disease.

Objectives: The objective of this study is to evaluate the mild physiologic changes of elastase-induced pulmonary emphysema in the pig by radionuclide scintigraphy and to correlate these findings with high-resolution computed tomography (HRCT) and histologic examination., Methods: Eight 7- to 12-week-old Yorkshire pigs were studied. Perfusion and ventilation studies were performed in six pigs at 1- or 2-week intervals after elastase instillation. HRCT was simultaneously performed for correlation with radionuclide scintigraphy. For the perfusion scans, technetium 99m (99mTc) macroaggregated albumin (MAA) was used, and both planar and single-photon emission CT (SPECT) images were obtained. Ventilation studies were performed with xenon-133 gas with dynamic sequential imaging., Results: Histopathologic findings demonstrated dilatation and destruction of the alveoli and were similar to those previously reported by the authors. The SPECT perfusion images showed significantly impaired perfusion of the involved segment of the lung, corresponding to the region where elastase was instilled. The planar xenon-133 ventilation scintigraphy did not show abnormal air trapping. The mild emphysema induced with elastase manifested as decreased and impaired perfusion with no detectable ventilation abnormalities. The sensitivity of SPECT perfusion studies for the detection of the mild changes of elastase-induced pulmonary emphysema were higher than that of HRCT., Conclusions: The perfusion studies reflect functional or physiologic changes in contrast to structural changes seen on HRCT. This pig model was valuable to study the scintigraphic manifestation of elastase-induced pulmonary emphysema.

The authors evaluated the early morphologic changes of elastase-induced pulmonary emphysema in the pig and correlated the findings with high-resolution computed tomography (HRCT). Nine Yorkshire pigs were included in this investigation; in seven, pulmonary emphysema was induced by 2 mg/kg body weight of elastase instilled selectively into the left lower lobe bronchus. Animals were studied by CT at 0, 1, 2, 3, 7, 14, and 21 days. At the completion of the experiment, the lungs were removed, inflated, fixed and dried, and subsequently sliced corresponding to the CT sections. The gross appearance, histologic appearance, and HRCT were correlated. On HRCT, sequential changes from early edema to development of emphysema were noted. Panlobular, centrilobular and paraseptal emphysema were observed. Elastase-induced pulmonary emphysema in the pig is a useful and reproducible animal model, and high-resolution computed tomography depicts the morphologic changes observed both by gross pathologic observations and histologic observations.

Standard, thin-section, and reference phantom computed tomography (CT) were performed to evaluate 75 consecutive patients with solitary pulmonary nodules. Follow-up was available for 62 nodules in 59 patients; 53 of the nodules were benign and nine were malignant. Twenty-one of the 62 nodules were assessed as benign with thin-section CT, while 33 of the 62 nodules were assessed as benign with reference phantom CT. Two of the nodules classified as benign with both thin-section and reference phantom CT proved to be malignant (a peripheral, ossified carcinoid and a 3.5-cm-diameter calcified carcinoma). The sensitivity of reference phantom CT (58%) for classification of benign nodules was higher than the sensitivity of thin-section CT (36%). The sensitivity of standard CT was lowest (12%). The presence of fat at thin-section CT was a reliable criterion for benignancy in six hamartomas. While both thin-section and reference phantom CT were useful in the identification of benign pulmonary nodules, reference phantom CT increased sensitivity by 22% compared with thin-section CT.

Left ventricular end-diastolic pressure (LVEDP) is a reliable indicator of the diastolic function of the left ventricle. The purpose of this study was to correlate the radiographic assessment of pulmonary hemodynamics with LVEDP. The study population consisted of 104 consecutive patients with four categories of LVEDP: less than 13 mm Hg (n = 26), 13-19 mm Hg (n = 30), 20-24 mm Hg (n = 24), and more than 24 mm Hg (n = 24). Chest radiographs obtained within 24 hours of cardiac catheterization were assessed for evidence of congestive heart failure (CHF) by three experienced radiologists. Findings were graded from 0 to 3 (normal to abnormal) on the basis of the following signs of CHF: redistribution, perihilar and perivascular haze, peribronchial cuffing, pulmonary artery-bronchus ratio, septal lines, subpleural edema, air-space edema, pleural effusion, cardiomegaly, and overall radiographic assessment of CHF. A consensus report was then generated. In patients with LVEDP over 20 mm Hg, 38% did not show CHF in the overall assessment. Correlation between radiographic signs of CHF and LVEDP was limited.

The purpose of this investigation was to optimize the reconstruction algorithm and the slice thickness of computed tomography (CT) for the study of the fine structure of the lung. In 75 patients, we performed routine thoracic CT examination and obtained two high-resolution CT (HRCT) slices at the same level using the standard and bone algorithms, or using the slice thickness of 1.5 mm and 3.0 mm. Side-by-side comparison of the standard and bone images revealed that more branching of the small vessels and more small bronchi could be recognized on the bone image than on the standard image. Thickened bronchovascular bundles and interlobular septa were demonstrated more clearly on the bone image than on the standard image. There was no significant difference in the CT attenuation value between the standard and bone images. The difference between 1.5 mm and 3.0 mm images when demonstrating the small vessels and bronchi was minimal in such lesions as lymphangitis carcinomatosa and radiation fibrosis. Thus HRCT, with a slice thickness of 1.5 mm and 3.0 mm reconstructed by the bone algorithm, is suitable for the demonstration of the fine structure of the lung.