Longitudinal Stream Research Articles

Tectonic versus rock-controlled mountain fronts – Geomorphometric and geostatistical approach (Sowie Mts., Central Europe)

Distinguishing between mountain fronts of various origins is an issue of considerable scientific and practical importance. Whereas morphometry is often applied to fault-generated fronts and a range of indices has been proposed to assess their activity, comparative studies of fault-generated and fault-line escarpments seem very rare. In this paper we analyze two mountain fronts delimiting the Sowie Mountains block (SW Poland, Central Europe) from the opposite sides. One is evidently a fault-generated escarpment, whereas the other one coincides with a distinct lithological boundary, although along an old Variscan fault, and appears to be a fault-line escarpment. These two fronts are characterized in terms of sinuosity, spacing ratio, slope characteristics, altitude variability using geostatistical approach, longitudinal stream profiles, drainage basin characteristics and the presence of mid-slope flats within the elevated block. Clustering and statistical hypothesis testing were used to recognize patterns of spatial similarities and differences. The main findings emerging from this study are as follows. The two mountain fronts are different in terms of morphological characteristics, but only some indices and parameters have discriminating value, mainly SL index, drainage basin typology, altitude variability in the frontal zone. Some parameters, such as drainage basin asymmetry and the altitude position of water divide flats, change non-systematically and their interpretation remains ambiguous. Their variability probably reflects local controls. Overall, the results strongly indicate that geomorphic histories of the mountain fronts and overarching controls of their long-term evolution were different. Morphometric properties and landform features, if considered in isolation and without statistical treatment, appear to be ambiguous in interpretation. This applies particularly to drainage basin properties. However, drainage basin clustering using a k-means algorithm helped to discriminate between the fronts and may be recommended for similar studies elsewhere.

Velocity rate of screw streams in the site of submerged vanes

Introduction. The formation mechanism of longitudinal screw streams (LSS) along the upstream and downstream face of submerged vanes (SV) is considered. Acting along with the artificial transversal circulation (ATC), these streams protect the water intake from the channel sediments. The intensities and directions of LSS and ATC depend on the regime of flow, the planned-geometric characteristics of the vanes. Recommendations concerning the purpose of SV’s rational characteristics in the aspect of steady formation of all three protective streams in the flow for river damless intakes are contradictory and require clarification. The purpose of the study is to analyze the velocity rate of the LSS in SV site at various planned-geometric characteristics of the vane and hydraulic modes of its operation based on a physical model with an erosion-resistant channel (without water separation), as well as to determine an efficient range of setting angles of the SV’s to the tray board in terms of formation of steady and intensive LSS along the upstream and downstream face of the vane.
 Materials and methods. Model physical hydraulic studies and theoretical calculations were used. Five hydraulic modes of SV’s operation were studied, with various planned-geometric characteristics, using the physical model with an erosion-resistant channel (without water separation). The obtained experimental data were summarized and analyzed.
 Results. Results of laboratory hydraulic studies of LSS velocity rate in LSS site were presented. Experimental graphic dependence diagrams were plotted characterizing the intensity and direction of the LSS along upstream and downstream faces of the vane.
 Conclusions. A determining influence of the setting angle of the vane to the tray board (bank line) on the intensity and direction of the LSS in SV’s site was found out. Experimentally, an efficient SV setting angle was determined in terms of the formation of steady and intensive LSS along the upstream and the downstream vane face with practically usable direction.

Test-retest reliability and sample size estimates after MRI scanner relocation

ObjectiveMany factors can contribute to the reliability and robustness of MRI-derived metrics. In this study, we assessed the reliability and reproducibility of three MRI modalities after an MRI scanner was relocated to a new hospital facility. MethodsTwenty healthy volunteers (12 females, mean age (standard deviation) ​= ​41 (11) years, age range [25–66]) completed three MRI sessions. The first session (S1) was one week prior to the 3T GE HDxt scanner relocation. The second (S2) occurred nine weeks after S1 and at the new location; a third session (S3) was acquired 4 weeks after S2. At each session, we acquired structural T1-weighted, pseudo-continuous arterial spin labelled, and diffusion tensor imaging sequences. We used longitudinal processing streams to create 12 summary MRI metrics, including total gray matter (GM), cortical GM, subcortical GM, white matter (WM), and lateral ventricle volume; mean cortical thickness; total surface area; average gray matter perfusion, and average diffusion tensor metrics along principal white matter pathways. We compared mean MRI values and variance at the old scanner location to multiple sessions at the new location using Bayesian multi-level regression models. K-fold cross validation allowed identification of important predictors. Whole-brain analyses were used to investigate any regional differences. Furthermore, we calculated within-subject coefficient of variation (wsCV), intraclass correlation coefficient (ICC), and dice similarity index (SI) of cortical segmentations across scanner relocation and within-site. Additionally, we estimated sample sizes required to robustly detect a 4% difference between two groups across MRI metrics. ResultsAll global MRI metrics exhibited little mean difference and small variability (bar cortical gray matter perfusion) both across scanner relocation and within-site repeat. T1- and DTI-derived tissue metrics showed ​< ​|0.3|% mean difference and <1.2% variance across scanner location and <|0.4|% mean difference and <0.8% variance within the new location, with between-site intraclass correlation coefficient (ICC) ​> ​0.80 and within-subject coefficient of variation (wsCV) ​< ​1.4%. Mean cortical gray matter perfusion had the highest between-session variability (6.7% [0.3, 16.7], estimate [95% uncertainty interval]), and hence the smallest ICC (0.71 [0.44,0.92]) and largest wsCV (13.4% [5.4, 18.1]). No global metric exhibited evidence of a meaningful mean difference between scanner locations. However, surface area showed evidence of a mean difference within-site repeat (between S2 and S3). Whole-brain analyses revealed no significant areas of difference between scanner relocation or within-site. For all metrics, we found no support for a systematic difference in variance across relocation sites compared to within-site test-retest reliability. Necessary sample sizes to detect a 4% difference between two independent groups varied from a maximum of n ​= ​362 per group (cortical gray matter perfusion), to total gray matter volume (n ​= ​114), average fractional anisotropy (n ​= ​23), total gray matter volume normalized by intracranial volume (n ​= ​19), and axial diffusivity (n ​= ​3 per group). ConclusionCortical gray matter perfusion was the most variable metric investigated (necessitating large sample sizes to identify group differences), with other metrics showing substantially less variability. Scanner relocation appeared to have a negligible effect on variability of the global MRI metrics tested. This manuscript reports within-site test-retest variability to act as a tool for calculating sample size in future investigations. Our results suggest that when all other parameters are held constant (e.g., sequence parameters and MRI processing), the effect of scanner relocation is indistinguishable from within-site variability, but may need to be considered depending on the question being investigated.

Simulation of the Pneumatic System of a Seed Drill with a Vertical Flow Direction

The purpose of the work is to reveal the influence of conical directing agents on the speed and trajectory of particles movement in the vertical pneumatic conduit of the sowing machine and to establish their rational parameters. With the help of numerical modeling the particle flight trajectories in the air flow were obtained. The carried out researches have shown expediency of application of the conical directing agent, allowing to take away a longitudinal stream of particles from walls of a pneumatic conduit and to centre their trajectories of movement along an axis of a pneumatic conduit. Particles are focused to the center of the distributor when the distributor covers the area of pneumatic conduit cross-section close to 25%.

Lives as Collections of Strands: An Essay in Descriptive Psychology

In this article I generalize the notion of multiple self-aspects to create a descriptive framework in which lives are partitioned into containers of activities called strands. Strands are nearly decomposable life modules, structured, stable, and concurrent longitudinal streams of extended duration whose momentary cross-sections constitute self-aspects. They are differentiated by five features: the person’s role, the cast, the setting, norms and values, and habits and routines. Strands contain projects and episodes and are replete with narrative. Each strand is continuous (i.e., strands persist when a person moves between them), and for the most part strands are mutually asynchronous. From a first-person perspective, the strands are continuous and concurrent, but only one strand is in the foreground at a given time (i.e., transitions between strands are akin to a figure-ground reversal). Furthermore, a life is different from the sum of its strands: It is a nonlinear system that can take on configurations not predictable from a comprehensive description of the individual strands. Two such examples are the achievement of greatness despite severe handicaps and instances of extreme self-sacrifice. I also discuss the research potential of a proposed smartphone app called LifeMaps.

MRI-Based Manual versus Automated Corpus Callosum Volumetric Measurements in Multiple Sclerosis.

Corpus callosum atrophy is a neurodegenerative biomarker in multiple sclerosis (MS). Manual delineations are gold standard but subjective and labor intensive. Novel automated methods are promising but require validation. We aimed to compare the robustness of manual versus automatic corpus callosum segmentations based on FreeSurfer. Nine MS patients (6 females, age 38±13 years, disease duration 7.3±5.2 years) were scanned twice with repositioning using 3-dimensional T1 -weighted magnetic resonance imaging on three scanners (two 1.5 T and one 3.0 T), that is, six scans/patient, on the same day. Normalized corpus callosum areas were measured independently by a junior doctor and neuroradiologist. The cross-sectional and longitudinal streams of FreeSurfer were used to segment the corpus callosum volume. Manual measurements had high intrarater (junior doctor .96 and neuroradiologist .96) and interrater agreement (.94), by intraclass correlation coefficient (P<.001). The coefficient of variation was lowest for longitudinal FreeSurfer (.96% within scanners; 2.0% between scanners) compared to cross-sectional FreeSurfer (3.7%, P = .001; 3.8%, P = .058) and the neuroradiologist (2.3%, P = .005; 2.4%, P = .33). Longitudinal FreeSurfer was also more accurate than cross-sectional (Dice scores 83.9±7.5% vs. 78.9±8.4%, P<.01 relative to manual segmentations). The corpus callosum measures correlated with physical disability (longitudinal FreeSurfer r = -.36, P<.01; neuroradiologist r = -.32, P<.01) and cognitive disability (longitudinal FreeSurfer r = .68, P<.001; neuroradiologist r = .64, P<.001). FreeSurfer's longitudinal stream provides corpus callosum measures with better repeatability than current manual methods and with similar clinical correlations. However, due to some limitations in accuracy, caution is warranted when using FreeSurfer with clinical data.

Longitudinal Mapping of Cortical Thickness Measurements: An Alzheimer's Disease Neuroimaging Initiative-Based Evaluation Study.

Longitudinal studies of development and disease in the human brain have motivated the acquisition of large neuroimaging data sets and the concomitant development of robust methodological and statistical tools for quantifying neurostructural changes. Longitudinal-specific strategies for acquisition and processing have potentially significant benefits including more consistent estimates of intra-subject measurements while retaining predictive power. Using the first phase of the Alzheimer's Disease Neuroimaging Initiative (ADNI-1) data, comprising over 600 subjects with multiple time points from baseline to 36 months, we evaluate the utility of longitudinal FreeSurfer and Advanced Normalization Tools (ANTs) surrogate thickness values in the context of a linear mixed-effects (LME) modeling strategy. Specifically, we estimate the residual variability and between-subject variability associated with each processing stream as it is known from the statistical literature that minimizing the former while simultaneously maximizing the latter leads to greater scientific interpretability in terms of tighter confidence intervals in calculated mean trends, smaller prediction intervals, and narrower confidence intervals for determining cross-sectional effects. This strategy is evaluated over the entire cortex, as defined by the Desikan-Killiany-Tourville labeling protocol, where comparisons are made with the cross-sectional and longitudinal FreeSurfer processing streams. Subsequent linear mixed effects modeling for identifying diagnostic groupings within the ADNI cohort is provided as supporting evidence for the utility of the proposed ANTs longitudinal framework which provides unbiased structural neuroimage processing and competitive to superior power for longitudinal structural change detection.

Experimental study on combustion characteristics and lean blow-out limits of non-premixed oxy-methane flames in a porous-plate reactor

The combustion characteristics and lean blow-out (LBO) limits of non-premixed oxy-methane flames in a face-to-face two-porous-plates reactor are experimentally investigated in this study. The reactor mimics the process of oxygen permeation and oxy-fuel combustion inside high-temperature membrane reactors (HTMRs). The fuel (CH4) was supplied together with CO2 in the main longitudinal stream while the oxygen was supplied via the upper and lower rectangular porous plates. The experiments were conducted over ranges of equivalence ratio (0.5, 0.7 and 1.0), CO2 percentage in the oxidizer mixture (0, 27, 35, 55 and 70%), and fuel firing rate (0.5, 0.75, 1.0, 1.5, 2, 2.5 and 3 kW). At fixed CO2%, there was insignificant increase in flame length while increasing the equivalence ratio. The flame luminous intensity was found to be decreasing while increasing CO2%. Increase in the LBO limit was obtained with the increase in the equivalence ratio at fixed fuel firing rate. The minimum limit of O2% to allow for a visible flame was found to be about 21% (79% CO2) at stoichiometric condition. The increase in fuel firing rate decreased CO2% at blow-out condition due to attainment of the required flow speed that overwhelmed the increase in flame speed.

Lateral ventricle volume trajectories predict response inhibition in older age-A longitudinal brain imaging and machine learning approach.

ObjectiveIn a three-wave 6 yrs longitudinal study we investigated if the expansion of lateral ventricle (LV) volumes (regarded as a proxy for brain tissue loss) predicts third wave performance on a test of response inhibition (RI).Participants and methodsTrajectories of left and right lateral ventricle volumes across the three waves were quantified using the longitudinal stream in Freesurfer. All participants (N = 74;48 females;mean age 66.0 yrs at the third wave) performed the Color-Word Interference Test (CWIT). Response time on the third condition of CWIT, divided into fast, medium and slow, was used as outcome measure in a machine learning framework. Initially, we performed a linear mixed-effect (LME) analysis to describe subject-specific trajectories of the left and right LV volumes (LVV). These features were input to a multinomial logistic regression classification procedure, predicting individual belongings to one of the three RI classes. To obtain results that might generalize, we evaluated the significance of a k-fold cross-validated f1-score with a permutation test, providing a p-value that approximates the probability that the score would be obtained by chance. We also calculated a corresponding confusion matrix.ResultsThe LME-model showed an annual ∼ 3.0% LVV increase. Evaluation of a cross-validated score using 500 permutations gave an f1-score of 0.462 that was above chance level (p = 0.014). 56% of the fast performers were successfully classified. All these were females, and typically older than 65 yrs at inclusion. For the true slow performers, those being correctly classified had higher LVVs than those being misclassified, and their ages at inclusion were also higher.ConclusionMajor contributions were: (i) a longitudinal design, (ii) advanced brain imaging and segmentation procedures with longitudinal data analysis, and (iii) a data driven machine learning approach including cross-validation and permutation testing to predict behaviour, solely from the individual’s brain “signatures” (LVV trajectories).

Comparative study between rivers in Tarim Basin in northwest China and Evros Vallis on Mars

The morphometric characteristics of the Kaidu River and Keriya River in the extremely arid Tarim Basin, and the Evros Vallis on Mars were compared to study the formation of the dendritic Evros Vallis, which has great significance for exploring ancient climate of Mars. The following results were obtained: (a) the average sinuosities of Kaidu River, Keriya River, and Evros Vallis are 1.17, 1.35, and 1.32 respectively. (b) the average bifurcation ratios are 3.84, 4.73 and 3.43 respectively. (c) the average stream length ratios are 2.21, 3.86 and 2.08 respectively. (d) the stream frequencies are 0.017, 0.028 and 0.002 respectively. (e) the drainage densities are 0.195 km−1 and 0.217 km−1, and 0.048 km−1 respectively. (f) the stream gradients are 3.74‰, 7.03‰ and 1.63‰ respectively. (g) the stream fractal dimensions are 1.70, 1.0 and 1.68 respectively. Paleodischarge estimations at different stream segments of Evros Vallis support the hypothesis that the V-bend area that joints the eastern and western segments possibly has a tectonic origin. Geomorphological evidence (e.g., tributaries) from high-resolution images and stream morphometric parameters from a comparative analysis (e.g., concave upward longitudinal profile and stream fractal dimension) support previous hypothesis that Evros Vallis is a mature drainage system formed by precipitation-driven surface runoff. This drainage process occurred either in a continuously warm-wet climate that lasted long enough on early Mars or in regional hydrologic cycles consisting of precipitation and occasionally returned runoff in intermittently clement climates.

Wearable bluetooth sensors for capturing relational variables and temporal variability in relationships: A construct validation study.

The advent of wearable sensor technologies has the potential to transform organizational research by offering the unprecedented opportunity to collect continuous, objective, highly granular data over extended time periods. Recent evidence has demonstrated the potential utility of Bluetooth-enabled sensors, specifically, in identifying emergent networks via colocation signals in highly controlled contexts with known distances and groups. Although there is proof of concept that wearable Bluetooth sensors may be able to contribute to organizational research in highly controlled contexts, to date there has been no explicit psychometric construct validation effort dedicated to these sensors in field settings. Thus, the two studies described here represent the first attempt to formally evaluate longitudinal Bluetooth data streams generated in field settings, testing their ability to (a) show convergent validity with respect to traditional self-reports of relational data; (b) display discriminant validity with respect to qualitative differences in the nature of alternative relationships (i.e., advice vs. friendship); (c) document predictive validity with respect to performance; (d) decompose variance in network-related measures into meaningful within- and between-unit variability over time; and (e) complement retrospective self-reports of time spent with different groups where there is a "ground truth" criterion. Our results provide insights into the validity of Bluetooth signals with respect to capturing variables traditionally studied in organizational science and highlight how the continuous data collection capabilities made possible by wearable sensors can advance research far beyond that of the static perspectives imposed by traditional data collection strategies. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Uplift analysis on a pericratonic region: An example in the Sierras de Córdoba (29°–34°S), Argentina

The Sierras de Córdoba (Argentina) is a mountain belt located in the most distal (pericratonic) part of the South-Central Andean foreland, in the easternmost end of the Sierras Pampeanas (Pampean ranges) broken foreland. Although this region is considered an excellent example for settings where basement thrusting generates relief and intermontane basin systems, hundreds of kilometers away from the Cordilleran front, the driving mechanisms and main controls on topography are still poorly understood. Given that the landscape, and particularly the rivers, react to changes in climate and tectonics on timescales between 103 and 106 yrs, we used DEM-based morphometry (elevation patterns, local relief, and analysis of 242 longitudinal stream profiles) to evaluate the main controls on modern topography. We focus on the morphologies of the main streams and their tributaries using metrics of the channel concavity and normalized channel steepness index (ksn). The distribution of local relief, concavity and ksn values was compared with the present-day topography, tectonic structures, rock-type and modern rainfall patterns. The stream longitudinal profiles show homogeneous concavities and ksn background values, with some local anomalies. Local structures (east and west vergent thrusts) in the Sierras de Córdoba seem to be the most fundamental controls on the formation of these anomalies, slope-break knickpoints as well as deep incision (high local relief). This suggests localized and accelerated rock uplift rates, which produce localized increases in the gradient along the longitudinal stream profile. It is important to notice that the highest ksn values were reported on the eastern range flanks, coincident with the highest values of mean annual rainfall. However, high ksn values appear to be maintained even with greater rainfall. Our study provides new insights on the Neogene Sierra de Córdoba uplift evolution, which will assist future sampling and modelling (cosmogenic nuclides analysis, thermochronology and GPS analysis).

22. Multicentric test-retest reproducibility of human hippocampal volumes with FreeSurfer 6.0: A comparison between standard and longitudinal hippocampal subfields segmentation streams applied to 3D T1, 3D FLAIR and high-resolution 2D T2 neuroimaging

Introduction The Italian AD-NET project is a multicentric initiative focused on the early recognition of Alzheimer’s Disease integrating clinical, imaging, and molecular data. This preliminary study reports test-retest reproducibility of hippocampus and its subfields segmentation, using the FreeSurfer 6.0 longitudinal processing with FLAIR alone and together with high-resolution T2. Materials and Methods Six clinical MRI sites across Italy currently participate in the project. The acquisition protocol included a 3D sagittal T1 both at the beginning and at the end of the scanning session, a 3D axial FLAIR and a high-resolution coronal T2. Each site recruited 5 healthy volunteers who were scanned in two different sessions a week apart. The preliminary results presented in this study are referred to 12 subjects. The images were processed according to the longitudinal stream of FreeSurfer 6.0. A within-session T1 averaging was performed to improve the reproducibility and FLAIR images were used in PIAL surface reconstruction. Then both standard hippocampal subfields segmentation (SHS) stream using the high-resolution T2 and longitudinal hippocampal subfields (LHS) stream were executed. The test-retest reproducibility error (RE) of the segmented volumes was calculated as the absolute volume differences across sessions relative to their mean. For each volume, the average RE value across subjects was calculated. Results The average RE related to the LHS stream ( ≈ 2%) is lower than using the SHS stream ( ≈ 3%). As shown in figure, the reproducibility with the LHS stream is higher for any volume except for the hippocampal fissure (Hp_ fiss). Irrespective of the stream used, the findings are generally better than those of other published studies, where no FLAIR and high-resolution T2 images were used. Conclusions Preliminary results of this study suggest high volume reproducibility for the different hippocampal subfields and the whole hippocampus. Moreover, the LHS stream showed a better reproducibility compared to the SHS stream. Acknowledgments This study was supported by the Italian Minister of Health, grant number: NET-2011-02346784.

Weight gain as a predictor of frontal and temporal lobe volume loss in bipolar disorder: A prospectiveMRIstudy

A sizable fraction of people with bipolar I disorder (BDI) experience a deteriorating clinical course with increasingly frequent mood episodes and chronic disability. This is believed to result from neurobiological illness progression, or neuroprogression. Excessive weight gain predicts neuroprogression across multiple brain illnesses, but no prospective studies have investigated this in BDI. The objective of this study was to determine whether BDI patients who experienced clinically significant weight gain (CSWG; gaining ≥7% of baseline weight) over 12months had greater 12-month brain volume loss in frontal and temporal regions important to BDI. In 55 early-stage BDI patients we measured (i) rates of CSWG, (ii) the number of days with mood symptoms, using NIMH LifeCharts, and (iii) baseline and 12-month brain volumes, using 3T MRI. We quantified brain volumes using the longitudinal processing stream in FreeSurfer v6.0. We used general linear models for repeated measures to investigate whether CSWG predicted volume loss, adjusting for potentially confounding clinical and treatment variables. After correction for multiple comparisons, CSWG in patients predicted greater volume loss in the left orbitofrontal cortex (effect size [ES; Cohen's d]=-1.01, P=0.002), left cingulate gyrus (ES=-1.31, P<0.001), and left middle temporal gyrus (ES=-0.96, P=0.004). Middle temporal volume loss predicted more days with depression (β=-0.406, P=0.010). These are the first prospective data on weight gain and neuroprogression in BDI. CSWG predicted neuroprogression, and neuroprogression predicted a worse clinical illness course. Trials of weight loss interventions are needed to confirm the causal direction of the weight gain-neuroprogression relationship, and to determine whether weight loss is a disease-modifying treatment.

Effect of glatiramer acetate on cerebral grey matter pathology in patients with relapsing-remitting multiple sclerosis

IntroductionIn this two year longitudinal study we compare the progression of grey matter (GM) damage in MS patients treated with glatiramer acetate (GA) for relapsing-remitting multiple sclerosis (RRMS) respect to untreated patients. MethodsWe studied thirty-five treated with GA and thirty-five untreated RRMS subjects matched for age, gender, disease duration and EDSS. Each patient underwent neurological examination every 6 months and 3-Tesla MRI at study entry (T0), after 1 year (T1) and 2 years (T2). At T0, T1 and T2, the number of new cortical lesions (CLs) was assessed on double inversion recovery images. By using the longitudinal stream of FreeSurfer, the cortical thickness and volume changes of several cerebral structures were evaluated after 2 years. ResultsThe mean number of new CLs was significantly lower in GA group compared to untreated patients both at T1 (0.9 ± 1.0 vs 1.7 ± 1.0, p < 0.05) and at T2 (1.4 ± 1.3 vs 2.9 ± 1.8, p < 0.001). Volume loss of thalamus (−0.5% ± 0.2% vs. −1.1% ± 0.4%; p < 0.001), globus pallidus (−4.4% ± 3.1% vs. −8.2% ± 4.5%; p < 0.001), hippocampus (−0.7% ± 0.3% vs. −1.5% ± 0.5%; p < 0.001) and cerebellum (−0.5% ± 0.3% vs. −0.9% ± 0.4%; p < 0.001) was also lower in the GA group. A more pronounced cortical thinning was observed in cingulate (p = 0.04), cuneus and frontomarginal gyrus (p = 0.01 for both comparisons) of the untreated patients. ConclusionOur findings suggest that GA exerts its immunomodulatory action at the level of GM either reducing the accumulation of CLs and slowing down the GM atrophy progression. Despite a confirmation in a larger sample size is required, our results suggest a possible effect of GA on GM damage.

Trajectories of brain development in school-age children born preterm with very low birth weight

Preterm birth (gestational age < 37 weeks) with very low birth weight (VLBW, birth weight ≤ 1500 g) is associated with lifelong cognitive deficits, including in executive function, and persistent alterations in cortical and subcortical structures. However, it remains unclear whether “catch-up” growth is possible in the preterm/VLBW brain. Longitudinal structural MRI was conducted with children born preterm with VLBW (n = 41) and term-born peers participating in the Norwegian Mother and Child Cohort Study (MoBa) (n = 128) at two timepoints in early school age (mean ages 8.0 and 9.3 years). Images were analyzed with the FreeSurfer 5.3.0 longitudinal stream to assess differences in development of cortical thickness, surface area, and brain structure volumes, as well as associations with executive function development (NEPSY Statue and WMS-III Spatial Span scores) and perinatal health markers. No longitudinal group × time effects in cortical thickness, surface area, or subcortical volumes were seen, indicating similar brain growth trajectories in the groups over an approximately 16-month period in middle childhood. Higher IQ scores within the VLBW group were associated with greater surface area in left parieto-occipital and inferior temporal regions. Among VLBW preterm-born children, cortical surface area was smaller across the cortical mantle, and cortical thickness was thicker occipitally and frontally and thinner in lateral parietal and posterior temporal areas. Smaller volumes of corpus callosum, right globus pallidus, and right thalamus persisted in the VLBW group from timepoint 1 to 2. VLBW children had on average IQ 1 SD below term-born MoBa peers and significantly worse scores on WMS-III Spatial Span. Executive function scores did not show differential associations with morphometry between groups cross-sectionally or longitudinally. This study investigated divergent or “catch-up” growth in terms of cortical thickness, surface area, and volumes of subcortical gray matter structures and corpus callosum in children born preterm/VLBW and did not find group × time interactions. Greater surface area at mean age 9.3 in left parieto-occipital and inferior temporal cortex was associated with higher IQ in the VLBW group. These results suggest that preterm VLBW children may have altered cognitive networks, yet have structural growth trajectories that appear generally similar to their term-born peers in this early school age window.

Contrasting Responses among Aquatic Organism Groups to Changes in Geomorphic Complexity Along a Gradient of Stream Habitat Restoration: Implications for Restoration Planning and Assessment

Many stream restoration projects aim to increase geomorphic complexity, assuming that this increases habitat heterogeneity and, thus, biodiversity. However, empirical data supporting these linkages remain scant. Previous assessments of stream restoration suffer from incomplete quantification of habitat complexity, or a narrow focus on only one organism group and/or one restoration measure, limiting learning. Based on a comprehensive quantification of geomorphic complexity in 20 stream reaches in northern Sweden, ranging from streams channelized for timber floating to restored and reference reaches, we investigated responses of macroinvertebrates, diatoms, and macrophytes to multiple geomorphic metrics. Sediment size heterogeneity, which was generally improved in restored sites, favored macroinvertebrate and diatom diversity and macroinvertebrate abundance. In contrast, macrophyte diversity responded to increased variation along the longitudinal stream profile (e.g., step-pools), which was not consistently improved by the restoration. Our analyses highlight the value of learning across multiple restoration projects, both in identifying which aspects of restoration have succeeded, and pinpointing other measures that might be targeted during adaptive management or future restoration. Given our results, a combination of restoration measures targeting not only sediment size heterogeneity, but also features such as step-pools and instream wood, is most likely to benefit benthic biota in streams.

Evolving population data linkage services to transform large-scale biobanking services

IntroductionMany population data linkage centres have been established to provide a mechanism for making linked administrative data available to approved third parties within robust governance frameworks. While current models support a wide variety of research, modifications are required for linked administrative data to better position biobanking research infrastructure.&#x0D; Objectives and ApproachWe have sought to reconfigure population data linkage services to enhance the value of a newly established state-of-the art population and disease biobank embedded within a state based pathology network, equipped with robotic technology, with the capacity to store and process more than 3 million samples from participants consenting to data linkage and future unspecified research.&#x0D; ResultsThree data service streams have been developed: longitudinal data linkage, cohort management and targeted recruitment. Traditional infrastructure for population data linkage will support the longitudinal data linkage stream, making data and biospecimens available for research, without direct patient identifiers. Technical and governance changes are necessary to enable the rapid release of contemporaneous patient and health system data for cohort management and recruitment purposes. The cohort management stream seeks to significantly reduce the manual follow-up of administrative data. The newly developed targeted recruitment service will leverage on the jurisdictional data holdings and structure of the health system and pathology network, to identify optimal sites and service providers for patient recruitment at scale, in an expedited manner.&#x0D; Conclusion/ImplicationsModest changes to population data infrastructure have significant potential to enhance biobank research infrastructure. By fast tracking biospecimen accrual for diseases of population subgroups of strategic importance, this new service is intended to promote biobank viability, accelerate the pace of clinical trials recruitment and improve patient access to trials.

Estimating fish alpha- and beta-diversity along a small stream with environmental DNA metabarcoding

Environmental DNA (eDNA) metabarcoding has been increasingly applied to biodiversity surveys in stream ecosystems. In stream networks, the accuracy of eDNA-based biodiversity assessment depends on whether the upstream eDNA influx affects downstream detection. Biodiversity assessment in low-discharge streams should be less influenced by eDNA transport than in high-discharge streams. We estimated α- and β-diversity of the fish community from eDNA samples collected in a small Michigan (USA) stream from its headwaters to its confluence with a larger river. We found that α-diversity increased from upstream to downstream and, as predicted, we found a significant positive correlation between β-diversity and physical distance (stream length) between locations indicating species turnover along the longitudinal stream gradient. Sample replicates and different genetic markers showed similar species composition, supporting the consistency of the eDNA metabarcoding approach to estimate α- and β-diversity of fishes in low-discharge streams.

Stream network conflation with topographic DEMs

This paper presents DEM-Stream-Conflation (DSC) algorithm – a scale-independent robust technique of aligning vector streams with flowpaths dictated by raster DEMs. Designed as an alternative to both stream-burning and threshold-dependent stream segmentation techniques, DSC utilizes the existing vector flowlines to identify the channel heads and a sink filled hydrologically conditioned DEM to resolve the flowpaths. The algorithm conceptually initiates the movement of water on a DEM at the starting node of channel heads, from which it traces the path of water to its ultimate watershed outlet. Each trace represents a stream, which is in perfect alignment with the direction dictated by the raster DEM. The algorithm is tested with different DEMs, and its efficacy is demonstrated through the replication of the original vector drainage pattern, derivation of geomorphic attributes that are independent of tested DEM scale, and the visualization of monotonically decreasing longitudinal stream profiles.