Longer Gaps Research Articles

The impact of COVID-19 on HIV treatment and care delivery in South and Southeast Asia: a qualitative study

The COVID-19 pandemic has significantly impacted HIV treatment worldwide, but its effects on South and Southeast Asia, particularly in India, Indonesia, and Thailand, have been less evident. Our aim was to study the perceptions of providers and policymakers to understand how interventions were implemented as part of pandemic responses and how their effectiveness was viewed. We conducted a qualitative study with semi-structured interviews focusing on the shifts in HIV care in response to the pandemic. Between June and July 2021, 40 individuals were invited for interviews; 33 (83%) agreed. Participants included 25 (76%) providers and 8 (24%) policymakers, who were from India (10; 30%), Indonesia (10; 30%), and Thailand (10; 30%), along with 3 (9.1%) regional policymakers. Sixteen (48%) were female. Our findings revealed four major themes: (1) limitations in accessing HIV care due to movement restrictions and shutdowns, such as transportation issues; (2) diversion of healthcare resources away from HIV care to COVID-19 responses, leading to reallocation of providers and hospital space; (3) setbacks in HIV-related policy implementation as COVID-19 emergency responses took priority; (4) the expansion of HIV differentiated service delivery interventions, allowing longer gaps between visits and larger-volume prescription refills to delay returns to healthcare facilities. These changes have raised concerns about the long-term consequences on HIV epidemic control and future pandemic responses. However, they have also presented opportunities for innovative care delivery, which should be sustained to address these challenges effectively.

Pediatric Palliative Epilepsy Surgery: A Report From the Pediatric Epilepsy Research Consortium (PERC) Surgery Database

BackgroundEpilepsy surgery is an underutilized resource for children with drug-resistant epilepsy. Palliative and definitive surgical options can reduce seizure burden and improve quality of life. Palliative epilepsy surgery is often seen as a “last resort” compared to definitive surgical options. We compare patient characteristics between palliative and definitive epilepsy surgical patients and present palliative surgical outcomes from the Pediatric Epilepsy Research Consortium surgical database. MethodsThe Pediatric Epilepsy Research Consortium Epilepsy Surgery database is a prospective registry of patients aged 0-18 years undergoing evaluation for epilepsy surgery at 20 pediatric epilepsy centers. We included all children with completed surgical therapy characterized as definitive or palliative. Demographics, epilepsy type, age of onset, age at referral, etiology of epilepsy, treatment history, time-to-referral/evaluation, number of failed anti-seizure medications (ASMs), imaging results, type of surgery, and postoperative outcome were acquired. ResultsSix hundred forty patients undergoing epilepsy surgery were identified. Patients undergoing palliative procedures were younger at seizure onset (median: 2.1 vs 4 years, P= 0.0008), failed more ASM trials before referral for presurgical evaluation (P=<0.0001), and had longer duration of epilepsy before referral for surgery (P=<0.0001). During presurgical evaluation, patients undergoing palliative surgery had shorter median duration of video-EEG data collected (P=0.007) but number of cases where ictal data were acquired was similar between groups. The most commonly performed palliative procedure was corpus callosotmy (31%), followed by lobectomy (21%) and neuromodulation (82% responsive neurostimulation vs 18% deep brain stimulation). Palliative patients were further categorized into traditionally palliative procedures vs traditionally definitive procedures. The majority of palliative patients had 50% reduction or better in seizure burden. Seizure free outcomes were significantly higher among those with traditional definitive surgeries, 41% (95% confidence interval: 26% to 57%) compared with traditional palliative surgeries and 9% (95% confidence interval: 2% to 17%). Rate of seizure freedom was 46% at 24 months or greater of follow-up in the traditional definitive group. ConclusionsPatients receiving palliative epilepsy surgery trialed more ASMs, were referred later after becoming drug resistant, and had longer gaps between drug resistance and epilepsy surgery compared with patients undergoing definitive epilepsy surgery. The extent of surgical evaluation is impacted if surgery is thought to be palliative. A majority of palliative surgery patients achieved >50% seizure reduction at follow-up, both in groups that received traditionally palliative and traditionally definitive surgical procedures. Palliative surgical patients can achieve greater seizure control and should be referred to an epilepsy surgery center promptly after failing two appropriate anti-seizure medications.

Performance of Transition Metal Supported Al2O3 Coated on Honeycomb Catalysts and Its Segmentation on Exhaust Gasses Oxidation

The oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) under segmented honeycomb catalysts was investigated using actual exhaust gas mixtures from a gasoline-fueled internal combustion engine of a motorcycle. The honeycomb catalysts were prepared through a wet process, resulting in four types coated with transition metals (Cu, Cr, Fe, and Ni) supported on Al2O3. The oxidation of CO and HC was monitored using an exhaust gas analyzer across a range of air-to-fuel ratios (AFR), from lean to rich, under stationary conditions. The results demonstrate that the honeycomb catalysts effectively decreased CO and HC concentrations in the exhaust gas. Among the transition metal oxide honeycomb catalysts, Cr and Ni exhibited high CO and HC conversion rates, surpassing those observed with Cu. The average CO and HC conversion calculations, spanning from lean to rich air-to-fuel ratios, were consistent with the actual conversion rates achieved. Furthermore, the study investigated the effect of honeycomb segmentation on CO and HC conversion. Surprisingly, the catalytic performance of Cr and Ni remained high even with longer gaps in the honeycomb. Interestingly, the conversion of CO and HC over the iron oxide honeycomb catalyst increased as the gap in the honeycomb became longer. This is likely due to an increase in the gap size and enhanced re-mixing of reactants (CO, HC, and O2) caused by recirculation. Thus, this study provides valuable elucidation on the potential application of segmented honeycomb catalysts for reducing CO and HC emissions in exhaust gases.

Predictors of Transition Outcomes in Cystic Fibrosis: Analysis of National Patient Registry and CF RISE (Responsibility. Independence. Self-care. Education) Data

ObjectiveTo identify predictors of change in lung function and body weight during healthcare transition in cystic fibrosis (CF). MethodsWe conducted a retrospective cohort study using data from the CF Foundation Patient Registry (CFFPR) and the web-based transition program CF RISE (Responsibility. Independence. Self-care. Education) for patients ages 16 to 25 who transitioned to adult care from 2013 through 2019. We modeled change in FEV1 % predicted and weight using linear regression fit with generalized estimating equations. Predictors included gap in care (time between last pediatric and first adult outpatient visit), transition program engagement, and sociodemographic and medical factors. ResultsAmong 12,420 adolescents and young adults (AYAs), 3,876 transitioned to adult care with a median gap in care of 7.6 months. Patients from CF centers with higher rates of CF RISE engagement had improved lung function and weight at their first adult outpatient visit. Coverage on a parent’s insurance plan and absence of CF complications predicted increased lung function. History of a non-lung transplant and sinus disease predicted increased weight. Comorbid diabetes mellitus and gaps in care >3 months predicted decreased lung function with longer gaps in care associated with greater decrease. A gap in care of 6-9 months predicted decreased weight. Control variables including baseline FEV1 and weight, and exacerbation status were also statistically significant. ConclusionsFindings suggest two promising targets to improve transition of AYAs with CF: increasing AYA engagement in CF RISE and reducing gaps in care during the transition period.

An atmospheric pressure plasma afterglow to charge ultrafine aerosol particles

A novel flowing plasma system aimed at increasing charging efficiency of particulate matter and effective removal through electrostatic precipitation is studied. Nanoparticles are passed through the spatial afterglow of an atmospheric pressure radio-frequency glow discharge plasma. Particle charging efficiencies and polarities are measured at different plasma-aerosol gaps, aerosol and plasma flow rates, plasma powers, and afterglow DC bias. Various timescales are calculated to explain the transport of charge carriers that facilitate particle charging processes. The experimental results showed increased charging efficiency and net positive charging at longer gaps between the afterglow and aerosol stream and lower aerosol flow rates. Timescale analysis indicates that when ample residence time is provided, transport of charge carriers shifts from ambi-polar diffusion to free diffusion, and electrons are rapidly lost from the afterglow, resulting in highly efficient, net positive charging of particles. The charging efficiency of particles in optimized operating conditions was comparable or higher than reported collection efficiencies of electrostatic precipitators. The findings overall demonstrate that glow discharges are capable of charging particles not immersed in the plasma bulk, and such systems show promise for improving performance of particle mitigation technology.

Graph Machine Learning for Improved Imputation of Missing Tropospheric Ozone Data.

Gaps in the measurement series of atmospheric pollutants can impede the reliable assessment of their impacts and trends. We propose a new method for missing data imputation of the air pollutant tropospheric ozone by using the graph machine learning algorithm "correct and smooth". This algorithm uses auxiliary data that characterize the measurement location and, in addition, ozone observations at neighboring sites to improve the imputations of simple statistical and machine learning models. We apply our method to data from 278 stations of the year 2011 of the German Environment Agency (Umweltbundesamt - UBA) monitoring network. The preliminary version of these data exhibits three gap patterns: shorter gaps in the range of hours, longer gaps of up to several months in length, and gaps occurring at multiple stations at once. For short gaps of up to 5 h, linear interpolation is most accurate. Longer gaps at single stations are most effectively imputed by a random forest in connection with the correct and smooth. For longer gaps at multiple stations, the correct and smooth algorithm improved the random forest despite a lack of data in the neighborhood of the missing values. We therefore suggest a hybrid of linear interpolation and graph machine learning for the imputation of tropospheric ozone time series.

Continuous speech with pauses inserted between words increases cortical tracking of speech envelope.

The decoding multivariate Temporal Response Function (decoder) or speech envelope reconstruction approach is a well-known tool for assessing the cortical tracking of speech envelope. It is used to analyse the correlation between the speech stimulus and the neural response. It is known that auditory late responses are enhanced with longer gaps between stimuli, but it is not clear if this applies to the decoder, and whether the addition of gaps/pauses in continuous speech could be used to increase the envelope reconstruction accuracy. We investigated this in normal hearing participants who listened to continuous speech with no added pauses (natural speech), and then with short (250 ms) or long (500 ms) silent pauses inserted between each word. The total duration for continuous speech stimulus with no, short, and long pauses were approximately, 10 minutes, 16 minutes, and 21 minutes, respectively. EEG and speech envelope were simultaneously acquired and then filtered into delta (1-4 Hz) and theta (4-8 Hz) frequency bands. In addition to analysing responses to the whole speech envelope, speech envelope was also segmented to focus response analysis on onset and non-onset regions of speech separately. Our results show that continuous speech with additional pauses inserted between words significantly increases the speech envelope reconstruction correlations compared to using natural speech, in both the delta and theta frequency bands. It also appears that these increase in speech envelope reconstruction are dominated by the onset regions in the speech envelope. Introducing pauses in speech stimuli has potential clinical benefit for increasing auditory evoked response detectability, though with the disadvantage of speech sounding less natural. The strong effect of pauses and onsets on the decoder should be considered when comparing results from different speech corpora. Whether the increased cortical response, when longer pauses are introduced, reflect improved intelligibility requires further investigation.

Digital Nerve Injury: Assessment and Treatment.

Undertreated digital nerve injuries may result in sensory deficits and pain. Early recognition and treatment will optimize outcomes, and providers should maintain a high index of suspicion when assessing patients with open wounds. Acute, sharp lacerations may be amenable to direct repair while avulsion injuries or delayed repairs require adequate resection and bridging with nerve autograft, processed nerve allograft, or conduits. Conduits are most appropriate for gaps less than 15 mm, and processed nerve allografts have demonstrated reliable outcomes across longer gaps.

Isoperistaltic gastric tube for long gap esophageal atresia (LGEA) in newborn, infants, and toddlers: a case-control study from a tertiary center.

Limited evidence exists about outcomes after gastric tube formation as "rescue" technique to avoid esophageal replacement in long gap esophageal atresia (LGEA). The last ERNICA Consensus Conference on the Management of LGEA has placed the techniques of gastric tubulization among the priorities for future research. Evaluate personal experience with Isoperistaltic Gastric Tube (IGT) and compare its outcomes with other more popular techniques for LGEA. A case-control study has been conducted. A retrospective monocentric analysis of LGEA patients (period: 2010-19) has been conducted in all consecutive IGT patients and each of these has been type matched with two cases of LGEA treated with other techniques. The follow-up (FU) considered was 24-months. IGT and controls showed no statistically significant differences regarding preoperative variables like sex, gestational age, birth weight, syndromes, and EA type. However, IGT patients had a significantly longer esophageal GAP under boost pressure (4.5 vertebral bodies vs. 3.6, p = 0.019) at time of surgery. The analysis showed no statistical difference among the two groups about perioperative outcomes, ICU, or overall postoperative stay. No differences have been shown between IGT and controls during the follow-up regarding GERD, esophagitis, fundoplication, dysphagia, vocal cord paralysis, stenosis, and dilatations, auxologic data, need for anastomosis revision, oral aversion, and death. Isoperistaltic Gastric Tube is safe and effective even in LGEA patients with longer gaps, with good perioperative, post-operative and middle-term outcomes. This procedure may be considered as an alternative to avoid esophageal substitution when a primary anastomosis seems impossible for a residual gap after traction and growth techniques.

Myopic macular Bruch’s membrane defects

PurposeTo examine histologic characteristics of macular Bruchś membrane defects (BMD) in axially elongated eyes. DesignHistomorphometric study. MethodsUsing light microscopy, we examined enucleated human globes for BMDs. ResultsIn 247 eyes, BMDs were detected in 15 (6.1%) eyes (axial length:27.0–36.0 mm), in 10 of them in the macular region. Prevalence and size of BMDs (mean:1.93 ± 1.62 mm; range:0.22mm–6.24 mm) correlated with longer axial length (OR:1.52; 95%CI:1.19,1.94; P = 0.001) and higher prevalence of scleral staphylomas (OR:16.3; 95%CI:2.67,99.3; P < 0.001). The BMDs were smaller than corresponding gaps in the retinal pigment epithelium (RPE) (1.93 ± 1.62 mm versus 2.61 mm ± 1.73 mm; P = 0.003), and larger than corresponding gaps in the inner nuclear layer (0.43 ± 0.76 mm; P = 0.008) and inner limiting membrane bridges (0.13 ± 0.33 mm; P = 0.001). Choriocapillaris thickness, BM thickness and RPE cell density did not vary (all P > 0.05) between the BDM border and adjacent areas. In the BMD, choriocapillaris and RPE were absent. The sclera was thinner in the BDM area than in adjacent areas (0.28 ± 0.19 mm versus 0.36 ± 0.13 mm; P = 0.006). ConclusionsBMDs as hallmarks of myopic macular degeneration are characterized by longer gaps in the RPE and smaller gaps in the outer nuclear layer and inner nuclear layer, by localized scleral thinning, and by a spatial association with scleral staphylomas. Thickness of the choriocapillaris and density of the RPE cell layer, both absent within the BDMs, do not vary between the BMD border and adjacent regions. The results suggest an association between BDMs and absolute scotomas, stretching of the adjacent retinal nerve fiver layer, and an axial elongation-associated stretching effect on BM as etiology of the BDMs.

Disparities in Loss to Follow-Up Among Adults With Congenital Heart Disease in North Carolina.

The AHA/ACC Adult Congenital Heart Disease guidelines recommend that most adults with congenital heart disease (CHD) follow-up with CHD cardiologists every 1 to 2 years because longer gaps in care are associated with adverse outcomes. This study aimed to determine the proportion of patients in North Carolina who did not have recommended follow-up and to explore predictors of loss to follow-up. Patients ages ≥18 years with a healthcare encounter from 2008 to 2013 in a statewide North Carolina database with an ICD-9 code for CHD were assessed. The proportion with cardiology follow-up within 24 months following index encounter was assessed with Kaplan-Meier estimates. Cox regression was utilized to identify demographic factors associated with differences in follow-up. 2822 patients were identified. Median age was 35 years; 55% were female. 70% were white, 22% black, and 3% Hispanic; 36% had severe CHD. The proportion with 2-year cardiology follow-up was 61%. Those with severe CHD were more likely to have timely follow-up than those with less severe CHD (72% vs 55%, P < .01). Black patients had a lower likelihood of follow-up than white patients (56% vs 64%, P = .01). Multivariable Cox regression identified younger age, non-severe CHD, and non-white race as risk factors for a lower likelihood of follow-up by 2 years. 39% of adults with CHD in North Carolina are not meeting AHA/ACC recommendations for follow-up. Younger and minority patients and those with non-severe CHD were particularly vulnerable to inadequate follow-up; targeted efforts to retain these patients in care may be helpful.

Impact of Different Types of Data Loss on Optimal Continuous Glucose Monitoring Sampling Duration.

Aims: To determine if a longer duration of continuous glucose monitoring (CGM) sampling is needed to correctly assess the quality of glycemic control given different types of data loss. Materials and Methods: Data loss was generated in two different methods until the desired percentage of data loss (10-50%) was achieved with (1) eliminating random individual CGM values and (2) eliminating gaps of a predefined time length (1-5 h). For CGM metrics, days required to cross predetermined targets for median absolute percentage error (MdAPE) for the different data loss strategies were calculated and compared with current international consensus recommendation of >70% of optimal data sampling. Results: Up to 90 days of CGM data from 291 adults with type 1 diabetes were analyzed. MdAPE threshold crossing remained virtually constant for random CGM data loss up to 50% for all CGM metrics. However, the MdAPE crossing threshold increased when losing data with longer gaps. For all CGM metrics assessed in our study (%T70-180, %T < 70, %T < 54, %T > 180, and %T > 250), up to 50% data loss in a random manner did not cause any significant change on optimal sampling duration; however, >30% of data loss in gaps up to 5 h required longer optimal sampling duration. Conclusions: Optimal sampling duration for CGM metrics depends on percentage of data loss as well as duration of data loss. International consensus recommendation for 70% CGM data adequacy is sufficient to report %T70-180 with 2 weeks of data without large data gaps.

Synergy of human platelet lysate and laminin to enhance the neurotrophic effect of human adipose-derived stem cells

Synergy of human platelet lysate and laminin to enhance the neurotrophic effect of human adipose-derived stem cells

Impact of Gaps in Care during Adult Care Transfer in Sickle Cell Disease

The transition from pediatric to adult health care is critical to the care of young adults with sickle cell disease (SCD). Young adults with SCD, compared with children with SCD, are at risk for a marked increase in disease severity, frequency of acute complications, healthcare utilization, and mortality. 1-4 Professional societies and healthcare experts recommend that young adults with chronic health conditions should transfer to adult-centered healthcare within 6 months of their last pediatric visit. 5-8 However, the effect of a 6-month transfer interval on healthcare utilization in SCD has not been studied. Given the complex health care needs of young adults with SCD, 9-15 it remains unclear whether the recommended 6-month transfer interval 5 is optimal. We hypothesized that longer gaps between pediatric and adult care would be associated with greater healthcare utilization in the first 2 to 6 years of adult care.This study included patients with SCD who were followed by a pediatric sickle cell program in the mid-southern US, participated in a transition to adult care program, 16 and fulfilled an initial adult visit to a partner adult SCD facility during the years 2011-2017. Participants were retrospectively followed from their first adult visit through December 31, 2017. Transfer gap was defined as the time (in months) between the last pediatric and the first adult sickle cell clinic visit. We estimated the association between varying transfer gaps from pediatric to adult care and the rate of healthcare utilization (inpatient, emergency department, and outpatient visits) in the first 2 to 6 years of adult care using negative binomial regression. Transfer gaps were evaluated at <2, ≥2 to <6, ≥6 to <9, and ≥9 months to evaluate whether adult health care utilization increased as the gap in SCD-specific care increased. Transfer gaps were also dichotomized at 6 months (>6 vs ≤6) to evaluate the current recommendation to complete transfer of patients to adult care within 6 months. 6,7 Healthcare resource utilization was analyzed for the complete follow-up (up to 6 years) and for the first 2 years of adult care to assess the immediate effects of delayed transfer.In total, 172 young adults with SCD (52% male, 63% HbSS/HbSβ 0-thalassemia) transferred to adult care at a median age of 18 years during the years 2011-2017 (Table 1). Approximately 83% of the included participants transferred to adult care within the recommended 6 months. young adults with transfer gaps ≥9 months had 2.86 (95%CI: 1.32, 6.20) times the rate of acute healthcare visits (inpatient and emergency department combined) compared to those with <2 months transfer gap (Table 2). The incidence rate ratio increased (IRR: 4.06; 95%CI: 1.65, 9.94) when evaluating the first 2 years of adult care. When evaluating the recommended transfer gap (6 months) as a dichotomous variable, those with gaps >6 months had 2.27 (95%CI: 1.18, 4.40) times the rate of acute care visits compared to those with ≤6 months transfer gap (Table 3). The incidence rate ratio increased slightly (IRR: 2.37; 95%CI: 1.29, 4.37) when evaluating the first 2 years of adult care only. There were no apparent associations between transfer gap duration and outpatient visits during the first 6 years in adult care; however, when restricted to the first 2 years of adult care, those with gaps >6 months had 1.32 (95%CI: 1.01, 1.72) times the rate of outpatient visits compared to those with gaps ≤6 months.Consistent with current guidelines, transfer gaps between pediatric and adult-centered care of greater than 6 months were found to be associated with increased acute healthcare resource utilization. Therefore, SCD transition programs would be well-served to consider policies for young adults that initiate adult care within 6 months of leaving pediatric care. Future studies should continue to investigate duration of transfer gaps from pediatric to adult care for their long-term clinical effects and explore interventions to reduce the transfer gap in the SCD population. [Display omitted] DisclosuresShah: Novartis: Consultancy, Research Funding, Speakers Bureau; GBT: Research Funding, Speakers Bureau; Alexion: Speakers Bureau; Guidepoint Global: Consultancy; GLG: Consultancy; Emmaus: Consultancy. Hankins: Bluebird Bio: Consultancy; UpToDate: Consultancy; Vindico Medical Education: Consultancy; Global Blood Therapeutics: Consultancy.

Modelling Place Visit Probability Sequences during Trajectory Data Gaps Based on Movement History

The acquisition of human trajectories facilitates movement data analytics and location-based services, but gaps in trajectories limit the extent in which many tracking datasets can be utilized. We present a model to estimate place visit probabilities at time points within a gap, based on empirical mobility patterns derived from past trajectories. Different from previous models, our model makes use of prior information from historical data to build a chain of empirically biased random walks. Therefore, it is applicable to gaps of varied lengths and can be fitted to empirical data conveniently. In this model, long gaps are broken into a chain of multiple episodes according to past patterns, while short episodes are estimated with anisotropic location transition probabilities. Experiments show that our model is able to hit almost 60% of the ground truth for short gaps of several minutes and over 40% for longer gaps up to weeks. In comparison, existing models are only able to hit less than 10% and 1% for short and long gaps, respectively. Visit probability distributions estimated by the model are useful for generating paths in data gaps, and have potential for disaggregated movement data analysis in uncertain environments.

Contraceptive Use Patterns among Women of Reproductive Age in Two Southeastern States.

Unintended pregnancies remain an important public health issue. Modern contraception is an important clinical service for reducing unintended pregnancy. This study examines contraception use among a representative sample of women residing in two southeastern U.S. states. A cross-sectional statewide survey assessing women's contraceptive use and reproductive health experiences was conducted in Alabama and South Carolina. Characteristics of the study population were compared across contraceptive use categories and multivariable regression analysis was performed examining relationships between covariates of interest and contraceptive use outcomes. Approximately 3,775 women were included in the study population. Overall, 26.5% of women reported not using any contraception. Short-acting hormonal methods were the most commonly reported (26.3%), followed by permanent methods (24.4%), long-acting reversible contraception (LARC; 14.3%), and barrier/other methods (8.5%). Nonuse was more prevalent among women with some college or an associate's degree, incomes between $25,000 and $50,000, no health insurance, and longer gaps in care. LARC use among women with Medicaid as a pay source was higher than use among privately insured women and higher in South Carolina than Alabama. Both nonuse and LARC use were higher among women with no insurance. Study findings are largely consistent with previous research using similar population-based surveys. LARC use was higher among the study population relative to what is observed nationally. Factors enabling access to contraceptive services, particularly for lower income women, were associated with contraception use patterns. These findings provide important context for understanding individuals' access to resources and are important for fostering increased access to contraceptive services among women in these two states.

Across‐frequency interference in visual temporal gap detection revisited

AbstractPurposeAt EVER2017, we reported that visual detection of a temporal gap becomes difficult when spatial frequency separation is introduced between markers delimiting the gap. In that report, however, gap thresholds were measured separately, in different runs, for within‐frequency and across‐frequency gap detection. Therefore, our previous findings may be simply explained by the effect of spatial‐frequency specific adaptation on visible persistence. Here, we reassessed the across‐frequency interference in gap detection using a procedure uncontaminated by spatial‐frequency specific adaptation.MethodsGaussian‐windowed sinusoidal gratings were used for gap markers. Spatial frequencies of the leading and trailing markers were manipulated to be either 2 or 4 cpd. Gap thresholds were measured using a two‐interval, two‐alternative forced choice method with a two‐down/one‐up interleaved adaptive staircase procedure targeting 70.7% correct detection: Four staircases corresponding to the four combinations of marker frequencies were interleaved in a single run and randomly selected in each trial. Sixteen observers with normal vision completed two runs, and the mean of estimated thresholds between two runs for each condition were subject to analysis.ResultsGap thresholds for across‐frequency markers (2‐4 and 4‐2 conditions) were significantly higher than those for within‐frequency markers (2‐2 and 4‐4 conditions). For within‐frequency gap detection, gap thresholds were significantly higher for 4 cpd than for 2 cpd markers, which was consistent with the well‐known decreased temporal resolution with increasing spatial frequency.ConclusionWe confirmed our previous findings that temporal gaps bounded by different frequency markers are more difficult to detect than those bounded by identical frequency markers. We propose that perceptual discontinuity signaling the frequency separation interferes with gap representation and longer gaps are required for correct gap detection.

Blue galaxies: modelling nebular He ii emission in high redshift galaxies

ABSTRACT Using cosmological simulations to make useful, scientifically relevant emission line predictions is a relatively new and rapidly evolving field. However, nebular emission lines have been particularly challenging to model because they are extremely sensitive to the local photoionization balance, which can be driven by a spatially dispersed distribution of stars amidst an inhomogeneous absorbing medium of dust and gas. As such, several unmodelled mysteries in observed emission line patterns exist in the literature. For example, there is some question as to why He ii λ4686/H β ratios in observations of lower metallicity dwarf galaxies tend to be higher than model predictions. Since hydrodynamic cosmological simulations are best suited to this mass and metallicity regime, this question presents a good test case for the development of a robust emission line modelling pipeline. The pipeline described in this work can model a process that produces high He ii λ4686/H β ratios and eliminate some of the modelling discrepancy for ratios below 3 per cent without including AGNs, X-ray binaries, high mass binaries, or a top-heavy stellar initial mass function. These ratios are found to be more sensitive to the presence of 15 Myr or longer gaps in the star formation histories than to extraordinary ionization parameters or specific star formation rates. They also closely correspond to the WR phase of massive stars. In addition to the investigation into He ii λ4686/H β ratios, this work charts a general path forward for the next generation of nebular emission line modelling studies.

Relationships between yield, rotation length, and abundance of Olpidium brassicae and Pyrenochaeta sp. in the rhizosphere of oilseed rape

Oilseed rape yields in the UK have been found to decline with more frequent cropping in a rotation. Previously, two soil-borne organisms (Olpidium brassicae (Chytridiomycota) and Pyrenochaeta sp. (Ascomycota)) were identified as having high relative abundance in rhizosphere fungal communities associated with oilseed rape crops where yield decline had been recorded. In order to better understand these organisms' association with the oilseed rape crop, the current study was designed to investigate the fungal rhizosphere microbiome of oilseed rape grown in a wide range of rotational frequencies. Samples collected from a long-term rotation trial site at three time points through the growing season were used to determine fungal community composition, and quantification of O. brassicae and Pyrenochatea sp. Analyses showed the combined root and rhizosphere fungal communities were similar across all oilseed rape rotations, largely due to the high relative abundance of O. brassicae, irrespective of cropping frequency. Olpidium brassicae abundance peaked in March (mid-season) in all rotations, before declining in abundance by June (pre-harvest). In contrast, Pyrenochaeta sp. increased in abundance throughout the season, with significantly higher levels reached in June than earlier in the season. Pyrenochaeta sp. had a greater abundance early in the season (January) in continuously grown and alternate oilseed rape (grown one year in two) than in rotations with longer gaps between oilseed rape crops This study concludes that O. brassicae cannot be solely associated with yield decline of OSR observed in short rotation cropping due to its prevalence in the extended rotations examined (up to 6-year gap).

Sex biased individual variation in movement patterns of a highly mobile, near-shore marine planktivore, the reef manta ray Mobula alfredi.

We examined individual variation and the role of sex on the movements of the reef manta ray Mobula alfredi. Specifically, we analysed several movement metrics using 6 years of nightly observations (1 January 2009-31 December 2014) of 118 individually identifiable manta rays at two discrete but spatially proximate sites, locally known as Manta Heaven and Manta Village, 15 km apart on the west side of the island of Hawaii, USA. Males were slightly more often (33.5%, model fitted mean, P < 0.05) observed than females at Manta Heaven, but females were much more often (156.4%, model fitted mean, P < 0.05) observed at Manta Village. Movement patterns among individuals varied greatly, but the level of variation was similar between sexes. Some animals, mainly females, displayed more resident patterns, whereas other, more mobile, animals moved between sites more frequently and had longer gaps between sightings. We did not detect discrete behavioural groups; rather, individuals varied along a continuous spectrum from many observations and high affinity to few observations and low fidelity to survey locations. These complex and variable movement patterns observed at the individual level, between sexes and between two nearby sites, in Hawaii's manta rays highlight the need for finer scale considerations in conservation and management of highly mobile marine populations.