Understanding the “Pathway” Towards a Searcher’s Learning Objective

Search systems are often used to support learning-oriented goals. This trend has given rise to the “search-as-learning” movement, which proposes that search systems should be designed to support learning. To this end, an important research question is: How does a searcher’s type of learning objective (LO) influence their trajectory (or pathway ) toward that objective? We report on a lab study (N = 36) in which participants gathered information to meet a specific type of LO. To characterize LOs and pathways , we leveraged Anderson and Krathwohl’s (A&K’s) taxonomy [ 3 ]. A&K’s taxonomy situates LOs at the intersection of two orthogonal dimensions: (1) cognitive process (CP) (remember, understand, apply, analyze, evaluate, and create) and (2) knowledge type (factual, conceptual, procedural, and metacognitive knowledge). Participants completed learning-oriented search tasks that varied along three CPs (apply, evaluate, and create) and three knowledge types (factual, conceptual, and procedural knowledge). A pathway is defined as a sequence of learning instances (e.g., subgoals) that were also each classified into cells from A&K’s taxonomy. Our study used a think-aloud protocol, and pathways were generated through a qualitative analysis of participants’ think-aloud comments and recorded screen activities. We investigate three research questions. First, in RQ1, we study the impact of the LO on pathway characteristics (e.g., pathway length). Second, in RQ2, we study the impact of the LO on the types of A&K cells traversed along the pathway. Third, in RQ3, we study common and uncommon transitions between A&K cells along pathways conditioned on the knowledge type of the objective. We discuss implications of our results for designing search systems to support learning.

Effect of Space Configurational Attributes on Social Interactions in Urban Parks

Urban parks are one of the most common spaces for social interactions in modern cities. The design of park spaces, especially space configuration, has significant influences on people’s social behaviors in parks. In this study, the associations between space configurational attributes and social interactions were investigated using space syntax theory. An observation analysis of social behaviors was carried out in two urban parks in Beijing, China. Nine space configurational attributes, including depth to the gate, depth to the main road, connectivity, normalized angular integration (NAIN), and normalized angular choice (NACH) with three radii, were calculated using a segment model. The variance analysis and regression analysis reveal the strong joint effect of space type, space scale factors, and space configurational attributes on social interaction behaviors in parks. The personal interaction group contained 23% of the total observed people involved in social interactions. Pathway length, zone area, and NACH-10K (NACH with a radius of 10,000 m) are positively associated with the number of people involved in personal interactions. For the social interaction group (77% of the total observed people), the space scale and depth to main city road were found to have a positive and negative influence on social interaction intensity.

Electrophysiological Characteristics of Intra‐Atrial Reentrant Tachycardia in Adult Congenital Heart Disease: Implications for Catheter Ablation

Background Ultra‐high‐density mapping enables detailed mechanistic analysis of atrial reentrant tachycardia but has yet to be used to assess circuit conduction velocity (CV) patterns in adults with congenital heart disease. Methods and Results Circuit pathways and central isthmus CVs were calculated from consecutive ultra‐high‐density isochronal maps at 2 tertiary centers over a 3‐year period. Circuits using anatomic versus surgical obstacles were considered separately and pathway length <50th percentile identified small circuits. CV analysis was used to derive a novel index for prediction of postablation conduction block. A total of 136 supraventricular tachycardias were studied (60% intra‐atrial reentrant, 14% multiple loop). Circuits with anatomic versus surgical obstacles featured longer pathway length (119 mm; interquartile range [IQR], 80–150 versus 78 mm; IQR, 63–95; P <0.001), faster central isthmus CV (0.1 m/s; IQR, 0.06–0.25 versus 0.07 m/s; IQR, 0.05–0.10; P =0.016), faster non‐isthmus CV (0.52 m/s; IQR, 0.33–0.71 versus 0.38 m/s; IQR, 0.27–0.46; P =0.009), and fewer slow isochrones (4; IQR, 2.3–6.8 versus 6; IQR 5–7; P =0.008). Both central isthmus ( R 2 =0.45; P <0.001) and non‐isthmus CV ( R 2 =0.71; P <0.001) correlated with pathway length, whereas central isthmus CV <0.15 m/s was ubiquitous for small circuits. Non‐isthmus CV in tachycardia correlated with CV during block validation ( R 2 =0.94; P <0.001) and a validation map to tachycardia conduction time ratio >85% predicted isthmus block in all cases. Over >1 year of follow‐up, arrhythmia‐free survival was better for homogeneous CV patterns (90% versus 57%; P =0.04). Conclusions Ultra‐high‐density mapping‐guided CV analysis distinguishes atrial reentrant patterns in adults with congenital heart disease with surgical obstacles producing slower and smaller circuits. Very slow central isthmus CV may be essential for atrial tachycardia maintenance in small circuits, and non‐isthmus conduction time in tachycardia appears to be useful for rapid assessment of postablation conduction block.

Middle trapezius transfer for treatment of irreparable supraspinatus tendon tears- anatomical feasibility study

Purpose The purpose of this study was to investigate the anatomical feasibility of a middle trapezius transfer below the acromion for treatment of irreparable supraspinatus tendon tears. Methods This study involved 20 human cadaveric shoulders in 10 full-body specimens. One shoulder in each specimen was dissected and assessed for muscle and tendon extent, force vectors, and distance to the neurovascular structures. The opposite shoulder was used to evaluate the surgical feasibility of the middle trapezius transfer via limited skin incisions along with an assessment of range of motion and risk of neurovascular injury following transfer. Results The harvested acromial insertion of the middle trapezius tendon showed an average muscle length of 11.7 ± 3.0 cm, tendon length of 2.7 ± 0.9 cm, footprint length of 4.3 ± 0.7 cm and footprint width of 1.4 ± 0.5 cm. The average angle between the non-transferred middle trapezius transfer and the supraspinatus was 33 ± 10° in the transversal plane and 34 ± 14° in the coronal plane. The mean distance from the acromion to the neurovascular bundle was 6.3 ± 1.3 cm (minimum: 4.0 cm). During surgical simulation there was sufficient excursion of the MTT without limitation of range of motion in a retracted scapular position but not in a protracted position. No injuries to the neurovascular structures were noted. Conclusion Transfer of the acromial portion of the middle trapezius for replacement of an irreparable supraspinatus seems to be feasible in terms of size, vector, excursion, mobility and safety. However, some concern regarding sufficiency of transfer excursion remains as scapula protraction can increase the pathway length of the transfer. Level of evidence Basic Science Study/Anatomical Study

Water Vapor Pathways during Freeze-Drying of Foamed Product Matrices Stabilized by Maltodextrin at Different Concentrations

This study aimed to identify the water-vapor transport mechanisms through an aerated matrix during microwave freeze-drying. Due to the larger surface area and lower water vapor transport resistance of an aerated product compared to the solution, foam structures dry faster. Different foam structures were produced with different maltodextrin (MD) concentrations (10–40%) as a foam-stabilizing agent. Depending on the initial viscosity of the solution prior to foaming, the samples differed in overrun (41–1671%) and pore size (d50 = 58–553 µm). Experiments were partially performed in a freeze-drying chamber of a light microscope to visualize structural changes in-situ. Different mechanisms were identified explaining the accelerated drying of foams, depending on the MD concentration, above or below 30%. At lower MD concentration, high overruns could be produced prior to freezing with big bubbles and thin lamellae with short diffusion pathway length. At 40% MD concentration, the viscosity was too high to integrate much air into the product. Therefore, the foam overrun was low and the bubble size small. Under these conditions, the water vapor generates high pressure, resulting in the formation of channels between bubbles, thus creating the pathways with low resistance for a very fast water vapor mass transfer. In addition, microwave freeze-drying experiments using a pilot plant unit were conducted to validate the findings of the freeze-drying microscope. A reduction of the drying time from 150 min (10% MD) to 78 min (40% MD) was achieved.

Circuit Determinants of Ventricular Tachycardia Cycle Length: Characterization of Fast and Unstable Human VT

Background: Fast ventricular tachycardias (VTs) have been historically attributed to shorter path lengths with smaller reentrant circuit dimensions in animal models. The relationship between the dimensions of the reentrant VT circuit and tachycardia cycle length (TCL) has not been examined in humans. This study aimed to analyze the determinants of the rate of human VT with comparison of circuit dimensions and conduction velocity (CV) across a wide range of both stable and unstable VTs delineated by high-resolution mapping. Methods: 54 VTs with complete circuit delineation (>90% TCL) by high-resolution multielectrode mapping were analyzed in 49 patients (male 88%, 65 years [58-71], nonischemic 47%). Fast VT was defined as TCL <333 ms (rate >180 bpm). Unstable VT was defined by hemodynamic deterioration with an intrinsic mean arterial pressure <60 mmHg during a sustained episode. Results: The median TCL of VT was 365 ms (306-443 ms) and 24 fast VTs with TCL<333ms (180 bpm) were characterized. A wide range of CV was observed within the entrance (0.03-0.55 m/s), common pathway (0.03-0.77 m/s), exit (0.03-0.53m/s), and outer loop (0.17-1.13 m/s). There were no significant differences in the median dimensions of the isthmus and path length between fast versus slow VTs and unstable versus stable VTs. The outer loop CV was the only circuit component that correlated with TCL both in ischemic cardiomyopathy (r=-0.5, p=0.006) and nonischemic cardiomyopathy(r=-0.45, p=0.028). The duration of the longest diastolic electrogram was inversely correlated with the dimensions of common pathway (length: r=-0.46, p=0.001, width: r=-0.3, p=0.047) and predictive of VT termination by a single radiofrequency application (r=-0.41, p=0.023). Conclusions: Due to a wide spectrum of CV observed within the reentrant path during human VT, the dimensions of the circuit were not predictive of VT cycle length. For the first time, we demonstrate that the CV of the outer loop, rather than isthmus, is the principal determinant of the rate of VT. The size of the circuit was similar between fast versus slow VTs and unstable versus stable VTs. Long, continuous electrograms were indicative of spatially confined isthmus dimensions, confirmed by rapid termination of VT during radiofrequency delivery.

Effect of a Concurrent Cognitive Task, with Stabilizing Visual Information and Withdrawal, on Body Sway Adaptation of Parkinsonian’s Patients in an Off-Medication State: A Controlled Study

Background: In persons with Parkinson’s disease (pwPD) any additional somatosensory or distractor interference can influence the posture. When deprivation of vision and dual-task are associated, the effect on biomechanical performance is less consistent. The aim of this study was to evaluate the role of the visual deprivation and a cognitive task on the static balance in earlier stage PD subjects. Methods: Fifteen off-medication state pwPD (9 women and 6 men), 67.7 ± 7.3 years old, diagnosed PD since 5.4 ± 3.4 years, only Hoehn and Yahr state 2 and fifteen young control adults (7 women and 8 men) aged 24.9 ± 4.9 years, performed semi-tandem task under four randomized experimental conditions: eyes opened single-task, eyes closed single-task, eyes opened dual-task and eyes closed dual-task. The center of pressure (COP) was measured using a force plate and electromyography signals (EMG) of the ankle/hip muscles were recorded. Traditional parameters, including COP pathway length, ellipse area, mediolateral/anteroposterior root-mean-square and non-linear measurements were computed. The effect of vision privation, cognitive task, and vision X cognitive was investigated by a 2 (eyes opened/eyes closed) × 2 (postural task alone/with cognitive task) repeated-measures ANOVA after application of a Bonferroni pairwise correction for multiple comparisons. Significant interactions were further analyzed using post-hoc tests. Results: In pwPD, both COP pathway length (p < 0.01), ellipse area (p < 0.01) and mediolateral/anteroposterior root-mean-square (p < 0.01) were increased with the eyes closed, while the dual-task had no significant effect when compared to the single-task condition. Comparable results were observed in the control group for who COP pathway was longer in all conditions compared to eyes opened single-task (p < 0.01) and longer in conditions with eyes closed compared to eyes opened dual-task (p < 0.01). Similarly, all differences in EMG activity of pwPD were exclusively observed between eyes opened vs. eyes closed conditions, and especially for the forward leg’s soleus (p < 0.01) and backward tibialis anterior (p < 0.01). Conclusions: These results in pwPD without noticeable impairment of static balance encourage the assessment of both visual occlusion and dual-task conditions when the appearance of significant alteration during the dual-task could reveal the subtle worsening onset of the balance control.

Mental development is associated with cortical connectivity of the ventral and nonspecific thalamus of preterm newborns

The thalamus is a key hub for regulating cortical connectivity. Dysmaturation of thalamocortical networks that accompany white matter injury have been hypothesized as neuroanatomical correlate of late life neurocognitive impairment following preterm birth. Our objective was to find a link between thalamocortical connectivity measures at term equivalent age and two year neurodevelopmental outcome in preterm infants. Diffusion tensor MRI of 58 infants (postmenstrual age at birth, mean (SD), 29.71 (1.47) weeks) was used to trace connections between the cortex and thalami. We found strong correlation between mental developmental index and two complementary measures of thalamocortical networks: connectivity strength projected to a cortical skeleton and pathway length emerging from thalamic voxels (partial correlation, R=0.552 and R=0.535, respectively, threshold-free cluster enhancement, corrected p-value<0.05), while psychomotor development was not associated with thalamocortical connectivity. Post hoc stepwise linear regression analysis revealed that parental socioeconomic scale, postmenstrual age and the duration of mechanical ventilation at the intensive care unit contribute to the variability of outcome. Our findings independently validated previous observations in preterm infants, providing additional evidence injury or dysmaturation of tracts emerging from ventral specific and various non-specific thalamus projecting to late-maturing cortical regions are predictive of mental, but not psychomotor developmental outcomes.

novoPathFinder: a webserver of designing novel-pathway with integrating GEM-model

To increase the number of value-added chemicals that can be produced by metabolic engineering and synthetic biology, constructing metabolic space with novel reactions/pathways is crucial. However, with the large number of reactions that existed in the metabolic space and complicated metabolisms within hosts, identifying novel pathways linking two molecules or heterologous pathways when engineering a host to produce a target molecule is an arduous task. Hence, we built a user-friendly web server, novoPathFinder, which has several features: (i) enumerate novel pathways between two specified molecules without considering hosts; (ii) construct heterologous pathways with known or putative reactions for producing target molecule within Escherichia coli or yeast without giving precursor; (iii) estimate novel pathways with considering several categories, including enzyme promiscuity, Synthetic Complex Score (SCScore) and LD50 of intermediates, overall stoichiometric conversions, pathway length, theoretical yields and thermodynamic feasibility. According to the results, novoPathFinder is more capable to recover experimentally validated pathways when comparing other rule-based web server tools. Besides, more efficient pathways with novel reactions could also be retrieved for further experimental exploration. novoPathFinder is available at http://design.rxnfinder.org/novopathfinder/.

Assessing surface flow pathway connectivity in semi-natural unimproved grasslands using structure from motion

&lt;p&gt;In addition to providing a valuable habitat, semi-natural unimproved grasslands may have significant value as part of natural flood management strategies. However, further understanding of the hydrological functioning of these landscapes is required and this study is developing new methods for using proximal remote sensing techniques to assess surface flow pathway connectivity.&lt;/p&gt;&lt;p&gt;Purple moor grass (&lt;em&gt;Molinia caerulea&lt;/em&gt;) dominated fields are seasonally saturated and have a dense tussock structure, hypothesised to result in long surface flow pathways with low hydrological connectivity and greater surface roughness than neighbouring intensively managed improved grassland. Quantifying these surface flow pathways required fine-scale understanding of topography not available from available datasets such as airborne LiDAR. After prescribed burning (a local management practice) at a study site in South West England, the underlying &lt;em&gt;M. caerulea&lt;/em&gt; tussock structure and flow pathways were exposed. A DJI Mavic Air quadcopter was flown over the &lt;em&gt;M. caerulea&lt;/em&gt; field shortly after to capture this structure. A neighbouring improved grassland field of similar size and slope was also surveyed.&lt;/p&gt;&lt;p&gt;Drone surveys were carried out using an automated flight path over an area of 1.7ha of &lt;em&gt;M. caerulea&lt;/em&gt; and 2.2 ha of improved grassland. Imagery was captured with an overlap/sidelap of 85% and with a ground sampling distance of 25m. Ground control points were geolocated, using a GNSS with an accuracy of ~0.03m to constrain subsequent structure from motion (SFM) photogrammetry processing.&lt;/p&gt;&lt;p&gt;SFM was used to create dense point clouds, from which digital surface models (DSM) of the two sites were derived at a resolution of 0.03m. The standard deviation of points within each DSM grid cell was also calculated to describe the uncertainty resulting from converting point cloud data to raster. An automated classification method was developed, in R using the LidR package, to identify individual &lt;em&gt;M. caerulea&lt;/em&gt; tussocks. The edges of tussocks were characterised by greater error due to the variability in topography and therefore could be used to identify tussock features.&lt;/p&gt;&lt;p&gt;The resulting DSMs were used to quantify surface flow pathway length in both sites using the Arc GIS flow routing algorithm. This included flow pathway length and drainage density (length of flow path per unit area). &lt;em&gt;M. caerulea&lt;/em&gt; had longer, more sinuous surface flow pathways through the dense tussocks, with an average drainage density of 2.54m m&amp;#175;&amp;#178;. This was significantly greater than drainage density in the improved field (1.82m m&amp;#175;&amp;#178;). Flow pathways in the improved grassland were straighter and more in-line with the slope in comparison. Longer, tenuous surface flow pathways in &lt;em&gt;M. caerulea&lt;/em&gt; sites theoretically result in a slower velocity of surface runoff, reduced soil erosion, greater evapotranspiration and root uptake than improved grassland sites. It is proposed that this understanding will be incorporated into hydrological modelling to improve understanding of the hydrological functioning and possible natural flood management potential of these landscapes.&lt;/p&gt;