Structural dynamics of plant-pollinator mutualistic networks.

The discourse surrounding the structural organization of mutualistic interactions mostly revolves around modularity and nestedness. The former is known to enhance the stability of communities, while the latter is related to their feasibility, albeit compromising the stability. However, it has recently been shown that the joint emergence of these structures poses challenges that can eventually lead to limitations in the dynamic properties of mutualistic communities. We hypothesize that considering compound arrangements-modules with internal nested organization-can offer valuable insights in this debate. We analyze the temporal structural dynamics of 20 plant-pollinator interaction networks and observe large structural variability throughout the year. Compound structures are particularly prevalent during the peak of the pollination season, often coexisting with nested and modular arrangements in varying degrees. Motivated by these empirical findings, we synthetically investigate the dynamics of the structural patterns across two control parameters-community size and connectance levels-mimicking the progression of the pollination season. Our analysis reveals contrasting impacts on the stability and feasibility of these mutualistic communities. We characterize the consistent relationship between network structure and stability, which follows a monotonic pattern. But, in terms of feasibility, we observe nonlinear relationships. Compound structures exhibit a favorable balance between stability and feasibility, particularly in mid-sized ecological communities, suggesting they may effectively navigate the simultaneous requirements of stability and feasibility. These findings may indicate that the assembly process of mutualistic communities is driven by a delicate balance among multiple properties, rather than the dominance of a single one.

Reduced pulmonary oxygen diffusion at 36 weeks of postmenstrual age in small-for-gestational-age preterm infants of less than 32 weeks without bronchopulmonary dysplasia.

BACKGROUND: Small-for-gestational-age (SGA) preterm infants are at increased risk of developing bronchopulmonary dysplasia (BPD). There is limited information on pulmonary oxygen diffusion of SGA preterm infants, particularly in those without BPD. OBJECTIVE: To compare the pulmonary oxygen diffusion of SGA to that of appropriate-for-gestational-age (AGA) preterm infants without BPD. STUDY DESIGN: Preterm infants with a gestational age (GA) between 24.0 and 31.6 weeks were studied. The oxygen saturation (SpO2 ), fraction to inspired oxygen (FiO2 ), and the SpO2 to FiO2 ratio (SFR) were compared between SGA and AGA infants. The association between SGA and SFR at 36 weeks was assessed using a multiple regression analysis. In the subgroup without BPD, SGA were match-paired for GA and gender with AGA infants. RESULTS: We analyzed 1189 infants surviving at 36 weeks: 194 (16%) were SGA and 995 (84%) AGA. The incidence of BPD was significantly higher in SGA than AGA infants (32% vs. 13%; p = .000). Out of the 995 infants without BPD, 132 (13%) were SGA and 863 (87%) AGA. SGA was negatively associated with the SFR value at 36 weeks, independently from BPD. SGA infants without BPD had significantly higher (better) SFR at birth, but lower (worse) SpO2 and SFR and from 33 to 36 weeks than their matched AGA counterpart. At 36 weeks, median SpO2 and SFR values were 97.7 versus 98.4 (p = .006) and 465 versus 468 (p = .010) in match-paired SGA and AGA, respectively. CONCLUSION: Among preterm infants of less than 32 weeks and without BPD, SGA infants had a reduced pulmonary oxygen diffusion at 36 weeks in comparison with AGA infants.

Who Needs a Second Dose of Exogenous Surfactant?

OBJECTIVE: To identify prenatal and postnatal risk factors associated with surfactant redosing. STUDY DESIGN: Retrospective, single-regional center study including all infants born from 24 + 0 to 31 + 6 weeks of gestation in the Marche Region, Italy, and admitted to a single level III regional NICU from January 1, 2004, to February 28, 2021. Clinical factors associated with surfactant redosing were identified through logistic regression analysis. RESULTS: Of 1615 consecutive admissions, 662 infants were treated with exogenous surfactant: 462 (70%) received a single dose and 200 (30%) received more than 1 dose (25.5% two doses and 4.5% three doses). Risk of redosing was higher for infants born to mothers with hypertension in pregnancy (OR 3.95, P < .001), for small for gestational age (SGA) infants (OR 3.93, P < .001) and when the first surfactant dose was 100 mg/kg instead of 200 mg/kg (OR 4.56/4.61, P < .001). Infants with greater GA, delayed first surfactant administration, and milder respiratory distress syndrome had reduced risk of redosing. Infants who required multiple surfactant doses had a higher rate of bronchopulmonary dysplasia and mortality, as well as longer duration of respiratory support than patients that received 1 dose. CONCLUSIONS: Hypertension in pregnancy and SGA status were found to be statistically and clinically significant predictors of surfactant redosing. Understanding the pathophysiology of these conditions requires further investigation.

Respiratory distress syndrome in preterm infants of less than 32 weeks: What difference does giving 100 or 200 mg/kg of exogenous surfactant make?

BACKGROUND: Surfactant dosing and effective delivery could affect continuous positive airways pressure (CPAP)-failure. Nevertheless, information on exogenous surfactant dosing with current administration methods is limited. OBJECTIVE: To describe the effect of 100 or 200 mg/kg of surfactant as first-line treatment of respiratory distress syndrome in preterm infants of less than 32 weeks gestation. STUDY DESIGN: A retrospective single-center cohort study comparing two epochs, before and after switching from 100 to 200 mg/kg surfactant therapy. RESULTS: Six hundred and fifty-eight of the 1615 infants of less than 32 weeks were treated with surfactant: 282 received 100 mg/kg (S-100) and 376 received 200 mg/kg (S-200). There were no differences between S-100 and S-200 in perinatal data including prenatal corticosteroids, medication use, age at first surfactant administration and respiratory severity before surfactant. The S-200 vs. S-100 had fewer retreatments (17.0% vs. 47.2%, p < 0.001) and a shorter duration of oxygen therapy and mechanical ventilation (315 vs. 339 h, p = 0.018; 37 vs. 118 h, p = 0.000, respectively). There was no difference in postnatal corticosteroid use (S-200 10.0% vs. S-100 11.0%, p = 0.361). Bronchopulmonary dysplasia (BPD) was significantly lower in S-200 vs. S-100 when comparing either the 4 and 6-year periods before and after the dose switch (29.4% vs. 15.7%, p = 0.003, and 18.7% vs. 27.3%, p = 0.024, respectively) CONCLUSIONS: The switch from 100 to 200 mg/kg was associated with a marked reduction in the need for surfactant redosing, respiratory support, and BPD. This information could be important when designing a study in the modern era of less invasive administration as surfactant dosing and its effective delivery may affect the outcome.

Early nasal continuous positive airway pressure failure prediction in preterm infants less than 32 weeks gestational age suffering from respiratory distress syndrome.

BACKGROUND: Early continuous positive airway pressure (CPAP) and surfactant replacement are effective treatments for neonatal respiratory distress syndrome (RDS). CPAP is the first line in preterm infants needing respiratory support, with surfactant replacement in case of CPAP failure (CPAP-F). OBJECTIVES: To analyze incidence and factors associated with CPAP-F in preterm infants with RDS. DESIGN, SETTING AND PATIENTS: Single-center retrospective database analysis (2004-2017) of inborn infants, gestational age (GA) 24 + 0/7-31 + 6/7 weeks, not intubated on admission to the neonatal intensive care unit, managed with CPAP. CPAP-F was defined as intubation and surfactant administration in the first 72 h of life; CPAP success (CPAP-S) was CPAP alone without need for additional RDS treatments. Demographic, respiratory, and clinical data associated with CPAP-F were studied using logistic regression analysis. RESULTS: A total of 562 infants met the inclusion criteria: 252 (44.8%) were CPAP-F and 310 (55.2%) were CPAP-S. The CPAP-F, compared to CPAP-S group, had lower GA and birth weight, and were less likely to receive antenatal steroids or to be vaginal births. Logistic regression showed that the fraction of inspired oxygen (FiO2 ) ≥ 0.23 between 180 and 240 min of life (FiO2 180-240 min) was the strongest factor associated with CPAP-F (odds ratio: 16.01 [95% confidence interval: 10.34-24.81]). CONCLUSION: FiO2 180-240 min was highly predictive of CPAP-F in preterm infants. With this model for surfactant administration/CPAP-F, 11.2% of infants would have unnecessarily received treatment, but importantly, 27.7% would have been treated much earlier, with a potential reduction in air leaks and duration of mechanical ventilation.

An ecological approach to structural flexibility in online communication systems.

Human cognitive abilities are limited resources. Today, in the age of cheap information-cheap to produce, to manipulate, to disseminate-this cognitive bottleneck translates into hypercompetition for rewarding outcomes among actors. These incentives push actors to mutualistically interact with specific memes, seeking the virality of their messages. In turn, memes' chances to persist and spread are subject to changes in the communication environment. In spite of all this complexity, here we show that the underlying architecture of empirical actor-meme information ecosystems evolves into recurring emergent patterns. We then propose an ecology-inspired modelling framework, bringing to light the precise mechanisms causing the observed flexible structural reorganisation. The model predicts-and the data confirm-that users' struggle for visibility induces a re-equilibration of the network's mesoscale towards self-similar nested arrangements. Our final microscale insights suggest that flexibility at the structural level is not mirrored at the dynamical one.

Debunking myths about contraceptive safety among women in Kingston, Jamaica: Pilot randomized controlled trial.

OBJECTIVES: (1) To create a short motion graphic video to debias women, using evidence from cognitive psychology, of 2 common myths about safety of intrauterine devices (IUDs) and implants in Jamaica; and (2) to conduct a pilot study to evaluate video effectiveness. STUDY DESIGN: We conducted a series of 3 focus group discussions among target users to inform the development process of the script, story, character, and look of the intervention video. We randomized young, female nonusers of long-acting contraception at risk of pregnancy at a public clinic in Kingston in 2018-2019 to watch either the intervention (n = 113) or control video (n = 112). We used logistical regression to evaluate perceptions of method safety, naturalness, and uptake after 3 months of follow up. RESULTS: Almost all (n = 220; 97.8%) participants completed the 3-month interview. More women in the intervention arm perceived IUDs to be safe (59.1%) compared to the control arm (43.6%; p = 0.02). Perceived implant safety increased from enrollment to follow up in the intervention and control arms (10.9 and 2.7 percentage-point increases, respectively); however, the difference between arms at follow up was not statistically significant (p = 0.57). This appeared to be due to arm imbalances at enrollment. Study arms did not differ at follow up in perceived IUD naturalness (p = 0.36) or implant naturalness (p = 0.68). CONCLUSIONS: Findings from a pilot study of a video intervention suggest that using debiasing strategies from cognitive psychology has the potential to address misconceptions about contraceptive safety. A larger trial with adequate power is warranted. IMPLICATIONS: Evidence from a pilot randomized controlled trial suggested that use of debiasing strategies from cognitive psychology could be effective in correcting women's misconceptions about contraception safety and thus show promise for the design of future contraceptive promotion videos to increase uptake.

Oxygen saturation to fraction of inspired oxygen ratio in preterm infants on routine parenteral nutrition with conventional or fish oil containing lipid emulsions.

INTRODUCTION: The benefits of intravenous (IV) fish oil (FO), as a source of n-3 long-chain polyunsaturated fatty acids, on lung growth in preterm infants, remain controversial. AIM: To evaluate if IV FO improves lung growth in small preterm infants on routine parenteral nutrition (PN). MATERIALS AND METHODS: We retrospectively reviewed prospectively collected data of preterm infants with a birth weight <1250 g who received routine PN from birth. We compared patients who received FO containing IV lipid emulsions with infants who received conventional emulsions (CNTR). The oxygen saturation (SpO2 ) to a fraction of inspired oxygen (FiO2 ) ratio (SFR) at 36 weeks (W) of gestation was chosen as the primary outcome variable to assess lung growth. RESULTS: Four hundred and seventy-seven infants were studied: 240 received IV FO and 237 CNTR. While exposure to antenatal glucocorticoids was higher in IV FO group than in CNTR (95 vs 90%, P = .04), there were no differences in birth data, enteral and parenteral nutrition intakes, ventilator supports and drug therapies. The incidence of the most common complications of prematurity at 36 W was not different (bronchopulmonary dysplasia was 27 vs 21% in IV FO vs CNTR infants, P = .1). Weight gain from birth to 36 W was marginally, but significantly, higher (+0.5 g/kg/d, P = .03) in IV FO group vs CNTR. SFR increased from 32 W to 36 W in all study patients (P < .001). IV FO infants had significantly lower SpO2 from 33 W to 35 W (P < .001) and lower (worse) SFR at 36 W (432 ± 57 vs 444 ± 51, P = .026) compared to CNTR. CONCLUSION: Contrary to our hypothesis, the use of FO containing IV lipid emulsions for the routine PN of the preterm infant did not improve lung growth compared to the infants who received conventional IV lipid emulsions.

Online division of labour: emergent structures in Open Source Software.

The development Open Source Software fundamentally depends on the participation and commitment of volunteer developers to progress on a particular task. Several works have presented strategies to increase the on-boarding and engagement of new contributors, but little is known on how these diverse groups of developers self-organise to work together. To understand this, one must consider that, on one hand, platforms like GitHub provide a virtually unlimited development framework: any number of actors can potentially join to contribute in a decentralised, distributed, remote, and asynchronous manner. On the other, however, it seems reasonable that some sort of hierarchy and division of labour must be in place to meet human biological and cognitive limits, and also to achieve some level of efficiency. These latter features (hierarchy and division of labour) should translate into detectable structural arrangements when projects are represented as developer-file bipartite networks. Thus, in this paper we analyse a set of popular open source projects from GitHub, placing the accent on three key properties: nestedness, modularity and in-block nestedness -which typify the emergence of heterogeneities among contributors, the emergence of subgroups of developers working on specific subgroups of files, and a mixture of the two previous, respectively. These analyses show that indeed projects evolve into internally organised blocks. Furthermore, the distribution of sizes of such blocks is bounded, connecting our results to the celebrated Dunbar number both in off- and on-line environments. Our conclusions create a link between bio-cognitive constraints, group formation and online working environments, opening up a rich scenario for future research on (online) work team assembly (e.g. size, composition, and formation). From a complex network perspective, our results pave the way for the study of time-resolved datasets, and the design of suitable models that can mimic the growth and evolution of OSS projects.

Oxygen saturation/FIO2 ratio at 36 weeks' PMA in 1005 preterm infants: Effect of gestational age and early respiratory disease patterns.

OBJECTIVE: To assess oxygen diffusion at 36 weeks' post-menstrual age in preterm infants by means of the non-invasive oxygen saturation/fraction of inspired oxygen ratio (36w-SFR) and to identify factors associated with 36w-SFR - ie, gestational age (GA) and early respiratory disease patterns (ERP). METHODS: Retrospective analysis of prospectively collected data. SETTING: Neonatal Intensive Care Unit. PATIENTS: 1005 preterm infants born below 32 weeks' GA. INTERVENTIONS: 36w-SFR was the mean of SFR values over 24 h on the day infants reached 36 weeks' PMA. MAIN OUTCOME MEASURES: 36w-SFR. STATISTICS: descriptive statistics, univariate, and multivariate analysis to study associations of 36w-SFR, including GA and ERP. RESULTS: 36w-SFR was significantly different between infants with and without bronchopulmonary dysplasia (BPD) (371 vs 467, P < 0.001), and according to ERP (LowFIO2 466, pulmonary improvement-PI 460, pulmonary deterioration-PD 405, early persistent pulmonary deterioration-EPPD 344, P < 0.001). Significant differences were found either in BPD and in non-BPD patients according to ERP (P < 0.001). Patients without BPD had significant differences in 36w-SFR according to GA (P < 0.001), while infants with BPD and increasing GA at birth had a non-significant trend for increased 36w-SFR (P = 0.621). Factors associated with 36w-SFR were GA, being small for GA, sepsis, human milk feeding, and ERP. CONCLUSIONS: Preterm infants without BPD had a spectrum of oxygen diffusion impairment that was inversely associated with GA at birth. Infants with different patterns of ERP had significant differences in 36w-SFR.

A two dimensional electromechanical model of a cardiomyocyte to assess intra-cellular regional mechanical heterogeneities.

Experimental studies on isolated cardiomyocytes from different animal species and human hearts have demonstrated that there are regional differences in the Ca2+ release, Ca2+ decay and sarcomere deformation. Local deformation heterogeneities can occur due to a combination of factors: regional/local differences in Ca2+ release and/or re-uptake, intra-cellular material properties, sarcomere proteins and distribution of the intracellular organelles. To investigate the possible causes of these heterogeneities, we developed a two-dimensional finite-element electromechanical model of a cardiomyocyte that takes into account the experimentally measured local deformation and cytosolic [Ca2+] to locally define the different variables of the constitutive equations describing the electro/mechanical behaviour of the cell. Then, the model was individualised to three different rat cardiac cells. The local [Ca2+] transients were used to define the [Ca2+]-dependent activation functions. The cell-specific local Young's moduli were estimated by solving an inverse problem, minimizing the error between the measured and simulated local deformations along the longitudinal axis of the cell. We found that heterogeneities in the deformation during contraction were determined mainly by the local elasticity rather than the local amount of Ca2+, while in the relaxation phase deformation was mainly influenced by Ca2+ re-uptake. Our electromechanical model was able to successfully estimate the local elasticity along the longitudinal direction in three different cells. In conclusion, our proposed model seems to be a good approximation to assess the heterogeneous intracellular mechanical properties to help in the understanding of the underlying mechanisms of cardiomyocyte dysfunction.

Hyperventilation syndrome in adolescents with and without asthma.

BACKGROUND: Data on the prevalence of hyperventilation syndrome (HVS) in adolescents are scanty. OBJECTIVES: To determine the prevalence of HVS in a population of adolescents with and without asthma, and to verify whether HVS was related to asthma activity. METHODS: A population of adolescents was asked to self-complete a questionnaire, including the Nijmegen questionnaire to assess HVS, and a standardized asthma questionnaire. RESULTS: Seven hundred and sixty questionnaires were suitable for analysis. One hundred and twenty subjects (15.8%) were classified as asthmatic. Forty-seven subjects (6.2%) had a Nijmegen score ≥ 23, which was suggestive of HVS. Symptoms indicative of HVS were ten times more common in subjects with asthma (25%) than in those without asthma (2.5%). Nijmegen score was significantly higher in subjects with lifetime asthma (P < 0.001), current episodic asthma (P < 0.05) and current active asthma (P < 0.001) than in those with no asthma. In the whole population, girls presented HVS more frequently than boys (P < 0.001). There was a significant effect of gender (females, OR 3.2) and status of asthma (lifetime asthma, OR 11.2; current episodic asthma, OR 8.9; current active asthma, OR 41.5) on the probability of suffering from HVS. CONCLUSIONS: The prevalence of symptoms indicative of HVS in an unselected population of adolescents was relatively high. Symptoms were more common in girls and in subjects with asthma, and there was a significant effect of asthma activity on the probability of suffering from HVS. Further studies need to be performed in order to validate a screening tool for HVS in both adolescents and asthmatic subjects.