Height Restrictions for Dual-energy X-ray Absorptiometry: What Are Our Options for Body Composition and Bone Health Precision?

ABSTRACT: Redinger, AL, Russell, JL, Allen, SMF, and Baker, BS. Height restrictions for dual-energy x-ray absorptiometry: what are our options for body composition and bone health precision? J Strength Cond Res XX(X): 000-000, 2024-Dual-energy X-ray absorptiometry (DXA) is commonly used for testing athlete's body composition, but many athletes are too tall. The first aim was to assess the viability of combining upper- and lower-body regions of interest (ROI), creating a combined scan for tall athletes who do not fit on the table and second, to provide practical solutions to DXA users who routinely scan tall athletes. Sixty subjects (34.8 ± 11.9 years; 171 ± 9 cm) completed 2 total-body DXA scans for baseline precision testing, using GE Lunar Prodigy (LP) or Hologic Horizon A (HA) models. Next, an upper body ROI from the skull to the distal femoral condyles was combined with a flipped scan (feet-to-head) ROI encompassing the proximal tibial plateau to the distal foot. Soft and bone tissue coefficient of variance (CV%) were calculated between the baseline scans and for the newly combined ROI scan. The combined ROI scan added 0.25-0.63% and 0.01-4.35% error rates for the LP and HA, respectively. An exploratory assessment of a GE Lunar iDXA demonstrated results similar to the HA with 4%+ error. The combined ROI scan is a user-friendly and precise method for older LP systems adding less than 1% error; however, newer DXA systems cannot use the stitched scan technique. Coaches and practitioners who use newer DXAs must prioritize consistently using the same boney landmarks (head, jaw, or feet) and ROI heights to provide precise longitudinal assessments of tall athletes' bone and body composition, until larger DXA tables become available.

External Load Fluctuations Across an Amateur Athletic Union Basketball Season.

ABSTRACT: Kutson, CW, Russell, JL, Strack, D, Coutts, AJ, and McLean, BD. External load fluctuations across an Amateur Athletic Union basketball season. J Strength Cond Res 38(3): 592-598, 2024-Amateur Athletic Union (AAU) competitions are an important component of the developmental pathway for youth basketball athletes. Despite its relative importance, there is currently a paucity of research investigating the physical demands in AAU basketball. Therefore, the purpose of this study was to examine the physical demands encountered over the course of an AAU basketball season. External training load was quantified using inertial sensors (Catapult T6) from one male AAU basketball team (age: 17.5 ± 0.5 years, height: 197.3 ± 10.0 cm, and mass: 89.4 ± 11.6 kg) over the course of the 2021 AAU season and categorized post hoc into high-, medium-, and low-minute groups based on mean playing minutes. After player categorization, 2 linear mixed models were constructed, one for PlayerLoad (PL) and one for duration, to examine the differences across player category, month of the season, and activity types (practices or games). The results show that the highest training loads were encountered by high-minute players, who had total PLs of 9,766 ± 1,516 AU, 13,207 ± 2,561 AU, and 7,071 ± 2,122 AU during April, May, and June, respectively. Highly variable training loads were also evident over the course of a season, with peak PL values as high as 4,921 AU per week. Practitioners should be aware that AAU basketball players experience variable loads throughout the season, which peak around congested competition/tournament periods. In addition, players with high game minutes accumulate the most load over the course of a season. This information may be used to better inform planning and periodizing strategies during developmental phases.

Finding the Signal in the Noise-Interday Reliability and Seasonal Sensitivity of 84 Countermovement Jump Variables in Professional Basketball Players.

ABSTRACT: Mercer, RAJ, Russell, JL, McGuigan, LC, Coutts, AJ, Strack, DS, and McLean, BD. Finding the signal in the noise-interday reliability and seasonal sensitivity of 84 countermovement jump variables in professional basketball players. J Strength Cond Res 37(2): 394-402, 2023-This study examined the measurement characteristics of countermovement jump (CMJ) variables in basketball athletes using different variable selection criteria. Test-retest reliability (noise) and seasonal variability (signal) CMJ data were collected from 13 professional basketball athletes playing for the same club throughout 1 competitive season. Interday reliability (coefficient of variation [CV] and intraclass correlation coefficients) were calculated over 3 preseason tests conducted on 3 consecutive days. To evaluate sensitivity, signal-to-noise ratio (SNR) was calculated by dividing seasonal variability (CV) from 8 in-season CMJ tests (collected from November to February) by preseason reliability (CV). Players performed 3 CMJs each testing day, and 3 data analysis techniques were applied: a single variable from the trial with either the best jump height (BestJH; calculated by flight time) or the best flight time to contraction time (BestFT:CT) and mean output across 3 jumps (Mean3). Mean3 was the most reliable data analysis technique, with 79 and 82 of 84 variables displaying lower interday CVs compared with BestJH and BestFT:CT, respectively. Overall, many CMJ measures display seasonal changes that are greater than the inherent noise, with 77 variables producing SNR of >1.00 for Mean3 compared with 65 and 58 variables for BestJH and BestFT:CT, respectively. To improve reliability and sensitivity, it is recommended that practitioners use the average of multiple CMJ trials and regularly reassess measurement characteristics specific to their cohort and environment.

Advanced fellowship training for cardiology fellows in acute care cardiology.

Hospitalised children have become more medically complex and increasingly require specialised teams and units properly equipped to care for them. Within paediatric cardiology, this trend, which is well demonstrated by the expansion of cardiology-specific ICUs, has more recently led to the development of acute care cardiology units to deliver team-based and condition-focused inpatient care. These care teams are now led by paediatric cardiologists with particular investment in the acute care cardiology environment. Herein, we describe the foundation and development of an Acute Care Cardiology Advanced Training Fellowship to meet the clinical, scholarly, and leadership training needs of this emerging care environment.

Understanding 'monitoring' data-the association between measured stressors and athlete responses within a holistic basketball performance framework.

This study examined associations between cumulative training load, travel demands and recovery days with athlete-reported outcome measures (AROMs) and countermovement jump (CMJ) performance in professional basketball. Retrospective analysis was performed on data collected from 23 players (mean±SD: age = 24.7±2.5 years, height = 198.3±7.6 cm, body mass = 98.1±9.0 kg, wingspan = 206.8±8.4 cm) from 2018-2020 in the National Basketball Association G-League. Linear mixed models were used to describe variation in AROMs and CMJ data in relation to cumulative training load (previous 3- and 10-days), hours travelled (previous 3- and 10-day), days away from the team's home city, recovery days (i.e., no travel/minimal on-court activity) and individual factors (e.g., age, fatigue, soreness). Cumulative 3-day training load had negative associations with fatigue, soreness, and sleep, while increased recovery days were associated with improved soreness scores. Increases in hours travelled and days spent away from home over 10 days were associated with increased sleep quality and duration. Cumulative training load over 3 and 10 days, hours travelled and days away from home city were all associated with changes in CMJ performance during the eccentric phase. The interaction of on-court and travel related stressors combined with individual factors is complex, meaning that multiple athletes response measures are needed to understand fatigue and recovery cycles. Our findings support the utility of the response measures presented (i.e., CMJ and AROMs), but this is not an exhaustive battery and practitioners should consider what measures may best inform training periodization within the context of their environment/sport.

Enhancing Implementation of Complex Critical Care Interventions through Interprofessional Education.

Background: Many critical care interventions that require teamwork are adopted slowly and variably despite strong evidence supporting their use. We hypothesize that educational interventions that target the entire interprofessional team (rather than professions in isolation) are one effective way to enhance implementation of complex interventions in the intensive care unit (ICU). Objective: As a first step toward testing this hypothesis, we sought to qualitatively solicit opinions about team dynamics, evidence translation, and interprofessional education as well as current knowledge, attitudes, and practices surrounding the use of one example of a team-based practice in the ICU-preventive postextubation noninvasive ventilation (NIV). Methods: We conducted a qualitative evaluation using semistructured interviews and focus groups with nurses, respiratory therapists, and physicians working in four ICUs in four hospitals within an integrated health system. ICUs were selected based on variation in academic versus community status. We iteratively analyzed transcripts using a thematic content analysis approach. Results: From December 2018 to January 2019, we conducted 32 interviews (34 people) and 3 focus groups (20 people). Participants included 31 nurses, 15 respiratory therapists, and 8 physicians. Participants had favorable views of how their teams work together but discussed ways team dynamics (e.g., leader inclusiveness) impact care coordination. Participants viewed interprofessional education favorably and shared suggestions regarding preferred content and delivery (e.g., include both profession-specific and team-oriented content). Though participants reported frequently using NIV as a treatment, they described rarely using NIV as a preventive strategy, and nurses and respiratory therapists described challenges to use such as perceived patient discomfort. There were ICU-specific differences in management of patients at a high risk for respiratory failure after extubation, with some preferring to delay extubation. Conclusion: Participants reported optimism that interprofessional education can be an acceptable and effective way to improve translation of evidence into practice. Participants also detailed patient-specific and ICU-wide barriers to the implementation of preventive postextubation NIV. This information about teamwork in the ICU, suggestions for interprofessional education, and barriers and facilitators to use of a target evidence-based practice can inform the development of novel educational strategies in ways that increase acceptability, appropriateness, and feasibility of the intervention.

Successful Reduction of Postoperative Chest Tube Duration and Length of Stay After Congenital Heart Surgery: A Multicenter Collaborative Improvement Project.

Background Congenital heart disease practices and outcomes vary significantly across centers, including postoperative chest tube (CT) management, which may impact postoperative length of stay (LOS). We used collaborative learning methods to determine whether centers could adapt and safely implement best practices for CT management, resulting in reduced postoperative CT duration and LOS. Methods and Results Nine pediatric heart centers partnered together through 2 learning networks. Patients undergoing 1 of 9 benchmark congenital heart operations were included. Baseline data were collected from June 2017 to June 2018, and intervention-phase data were collected from July 2018 to December 2019. Collaborative learning methods included review of best practices from a model center, regular data feedback, and quality improvement coaching. Center teams adapted CT removal practices (eg, timing, volume criteria) from the model center to their local resources, practices, and setting. Postoperative CT duration in hours and LOS in days were analyzed using statistical process control methodology. Overall, 2309 patients were included. Patient characteristics did not differ between the study and intervention phases. Statistical process control analysis showed an aggregate 15.6% decrease in geometric mean CT duration (72.6 hours at baseline to 61.3 hours during intervention) and a 9.8% reduction in geometric mean LOS (9.2 days at baseline to 8.3 days during intervention). Adverse events did not increase when comparing the baseline and intervention phases: CT replacement (1.8% versus 2.0%, P=0.56) and readmission for pleural effusion (0.4% versus 0.5%, P=0.29). Conclusions We successfully lowered postoperative CT duration and observed an associated reduction in LOS across 9 centers using collaborative learning methodology.

Image-guided chest tube drainage in the management of chylothorax post cardiac surgery in children: a single-center case series.

BACKGROUND: In children, chylothorax post cardiac surgery can be difficult to treat, may run a protracted course, and remains a source of morbidity and mortality. OBJECTIVE: To analyze the experience with percutaneous image-guided chest-tube drainage in the management of post-cardiac-surgery chylothoraces in children. MATERIALS AND METHODS: We conducted a single-center retrospective case series of 37 post-cardiac-surgery chylothoraces in 34 children (20 boys; 59%), requiring 48 drainage procedures with placement of 53 image-guided chest tubes over the time period 2004 to 2015. We analyzed clinical and procedural details, adverse events and outcomes. Median age was 0.6 years, median weight 7.2 kg. RESULTS: Attempted treatments of chylothoraces prior to image-guided chest tubes included dietary restrictions (32/37, 86%), octreotide (12/37, 32%), steroids (7/37, 19%) and thoracic duct ligation (5/37, 14%). Image-guided chest tubes (n=43/53, 81%) were single unilateral in 29 children, bilateral in 4 (n=8/53, 15%), and there were two ipsilateral tubes in one (2/53, 4%). Effusions were isolated, walled-off, in 33/53 (62%). In 20/48 procedures (42%) effusions were septated/complex. The mean drainage through image-guided chest tubes was 17.3 mL/kg in the first 24 h, and 13.4 mL/kg/day from diagnosis to chest tube removal; total mean drainage from all chest tubes was 19.6 mL/kg/day. Nine major and 27 minor maintenance procedures were required during 1,207 tube-days (rate: 30 maintenance/1,000 tube-days). Median tube dwell time was 21 days (range 4-57 days). There were eight mild adverse events, three moderate adverse events and no severe adverse events related to image-guided chest tubes. Radiologic resolution was achieved in 26/37 (70%). Twenty-three children (68%) survived to discharge; 11 children (32%) died from underlying cardiac disease. CONCLUSION: Management of chylothorax post-cardiac-surgery in children is multidisciplinary, requiring concomitant multipronged approaches, often through a protracted course. Multiple image-guided chest tube drainages can help achieve resolution with few complications. Interventional radiology involvement in tube care and maintenance is required. Overall, mortality remains high.

Quantifying Training and Game Demands of a National Basketball Association Season.

Purpose: There are currently no data describing combined practice and game load demands throughout a National Basketball Association (NBA) season. The primary objective of this study was to integrate external load data garnered from all on-court activity throughout an NBA season, according to different activity and player characteristics. Methods: Data from 14 professional male basketball players (mean ± SD; age, 27.3 ± 4.8 years; height, 201.0 ± 7.2 cm; body mass, 104.9 ± 10.6 kg) playing for the same club during the 2017-2018 NBA season were retrospectively analyzed. Game and training data were integrated to create a consolidated external load measure, which was termed integrated load. Players were categorized by years of NBA experience (1-2y, 3-5y, 6-9y, and 10 + y), position (frontcourt and backcourt), and playing rotation status (starter, rotation, and bench). Results: Total weekly duration was significantly different (p < 0.001) between years of NBA playing experience, with duration highest in 3-5 year players, compared with 6-9 (d = 0.46) and 10+ (d = 0.78) year players. Starters experienced the highest integrated load, compared with bench (d = 0.77) players. There were no significant differences in integrated load or duration between positions. Conclusion: This is the first study to describe the seasonal training loads of NBA players for an entire season and shows that a most training load is accumulated in non-game activities. This study highlights the need for integrated and unobtrusive training load monitoring, with engagement of all stakeholders to develop well-informed individualized training prescription to optimize preparation of NBA players.

Measuring Physical Demands in Basketball: An Explorative Systematic Review of Practices.

BACKGROUND: Measuring the physical work and resultant acute psychobiological responses of basketball can help to better understand and inform physical preparation models and improve overall athlete health and performance. Recent advancements in training load monitoring solutions have coincided with increases in the literature describing the physical demands of basketball, but there are currently no reviews that summarize all the available basketball research. Additionally, a thorough appraisal of the load monitoring methodologies and measures used in basketball is lacking in the current literature. This type of critical analysis would allow for consistent comparison between studies to better understand physical demands across the sport. OBJECTIVES: The objective of this systematic review was to assess and critically evaluate the methods and technologies used for monitoring physical demands in competitive basketball athletes. We used the term 'training load' to encompass the physical demands of both training and game activities, with the latter assumed to provide a training stimulus as well. This review aimed to critique methodological inconsistencies, establish operational definitions specific to the sport, and make recommendations for basketball training load monitoring practice and reporting within the literature. METHODS: A systematic review of the literature was performed using EBSCO, PubMed, SCOPUS, and Web of Science to identify studies through March 2020. Electronic databases were searched using terms related to basketball and training load. Records were included if they used a competitive basketball population and incorporated a measure of training load. This systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO Registration # CRD42019123603), and approved under the National Basketball Association (NBA) Health Related Research Policy. RESULTS: Electronic and manual searches identified 122 papers that met the inclusion criteria. These studies reported the physical demands of basketball during training (n = 56), competition (n = 36), and both training and competition (n = 30). Physical demands were quantified with a measure of internal training load (n = 52), external training load (n = 29), or both internal and external measures (n = 41). These studies examined males (n = 76), females (n = 34), both male and female (n = 9), and a combination of youth (i.e. under 18 years, n = 37), adults (i.e. 18 years or older, n = 77), and both adults and youth (n = 4). Inconsistencies related to the reporting of competition level, methodology for recording duration, participant inclusion criteria, and validity of measurement systems were identified as key factors relating to the reporting of physical demands in basketball and summarized for each study. CONCLUSIONS: This review comprehensively evaluated the current body of literature related to training load monitoring in basketball. Within this literature, there is a clear lack of alignment in applied practices and methodological framework, and with only small data sets and short study periods available at this time, it is not possible to draw definitive conclusions about the true physical demands of basketball. A detailed understanding of modern technologies in basketball is also lacking, and we provide specific guidelines for defining and applying duration measurement methodologies, vetting the validity and reliability of measurement tools, and classifying competition level in basketball to address some of the identified knowledge gaps. Creating alignment in best-practice basketball research methodology, terminology and reporting may lead to a more robust understanding of the physical demands associated with the sport, thereby allowing for exploration of other research areas (e.g. injury, performance), and improved understanding and decision making in applying these methods directly with basketball athletes.

Achieving Minimal Heat Conductivity by Ballistic Confinement in Phononic Metalattices.

Controlling the thermal conductivity of semiconductors is of practical interest in optimizing the performance of thermoelectric and phononic devices. The insertion of inclusions of nanometer size in a semiconductor is an effective means of achieving such control; it has been proposed that the thermal conductivity of silicon could be reduced to 1 W/m/K using this approach and that a minimum in the heat conductivity would be reached for some optimal size of the inclusions. Yet the experimental verification of this design rule has been limited. In this work, we address this question by studying the thermal properties of silicon metalattices that consist of a periodic distribution of spherical inclusions with radii from 7 to 30 nm, embedded into silicon. Experimental measurements confirm that the thermal conductivity of silicon metalattices is as low as 1 W/m/K for silica inclusions and that this value can be further reduced to 0.16 W/m/K for silicon metalattices with empty pores. A detailed model of ballistic phonon transport suggests that this thermal conductivity is close to the lowest achievable by tuning the radius and spacing of the periodic inhomogeneities. This study is a significant step in elucidating the scaling laws that dictate ballistic heat transport at the nanoscale in silicon and other semiconductors.

Center Variation in Chest Tube Duration and Length of Stay After Congenital Heart Surgery.

BACKGROUND: Nearly every child undergoing congenital heart surgery has chest tubes placed intraoperatively. Center variation in removal practices and impact on outcomes has not been well described. This study evaluated variation in chest tube management practices and outcomes across centers. METHODS: The study included patients undergoing any of 10 benchmark operations from June 2017 to May 2018 at participating Pediatric Acute Care Cardiology Collaborative (PAC3) and Pediatric Cardiac Critical Care Consortium (PC4) centers. Clinical data from PC4 centers were merged with chest tube data from PAC3 centers. Practices and outcomes were compared across centers in univariate and multivariable analysis. RESULTS: The cohort included 1029 patients (N = 9 centers). Median chest tube duration varied significantly across centers for 9 of 10 benchmark operations (all P ≤ .03), with a "model" center noted to have the shortest duration for 9 of 10 operations (range, 27.9% to 87.4% shorter duration vs other centers across operations). This effect persisted in multivariable analysis (P < .0001). The model center had higher volumes of chest tube output before removal (median, 8.5 mL/kg/24 h [model] vs 2.2 mL/kg/24 h [other centers]; P < .001], but it did not have higher rates of chest tube reinsertion (model center 1.3% vs 2.1%; P = .59) or readmission for pleural effusion (model center 4.4% vs 3.0%; P = .31), and had the shortest length of stay for 7 of 10 operations. CONCLUSIONS: This study suggests significant center variation in chest tube removal practices and associated outcomes after congenital heart surgery. Best practices used at the model center have informed the design of an ongoing collaborative learning project aimed at reducing chest tube duration and length of stay.

Adaptive Shape Ripening and Interparticle Bridging of l-Arginine-Stabilized Silica Nanoparticles during Evaporative Colloidal Crystal Assembly.

During evaporative self-assembly of colloidal crystal films, spherical l-arginine-stabilized silica colloids adapt to different close-packed geometries by faceting and forming bridge connections with their nearest neighbors. We systematically studied the morphological changes of 37 and 138 nm diameter colloids during evaporative assembly and compared them to 65 nm Stöber silica colloids prepared without l-arginine. Colloidal crystal films were grown from particles that had been dialyzed against water or l-arginine, and tetraethyl orthosilicate (TEOS) and/or l-arginine were added to solutions during colloidal film growth. Solid-state 29Si NMR spectra showed the presence of l-arginine and incompletely condensed silica in colloids grown from silica seeds in l-arginine solutions. These colloids were especially susceptible to chemical ripening during the colloidal assembly process, adopting faceted shapes that reflected the packing symmetry of the colloidal crystal films. The addition of l-arginine and TEOS accelerated these shape changes by catalyzing the hydrolysis and olation of silica and by adding a source of silica to the solution, respectively. This chemistry provides a route to single-component and binary colloidal crystals composed of nonspherical silica building blocks.

Colloidal crystal order and structure revealed by tabletop extreme ultraviolet scattering and coherent diffractive imaging.

Colloidal crystals with specific electronic, optical, magnetic, vibrational properties, can be rationally designed by controlling fundamental parameters such as chemical composition, scale, periodicity and lattice symmetry. In particular, silica nanospheres -which assemble to form colloidal crystals- are ideal for this purpose, because of the ability to infiltrate their templates with semiconductors or metals. However characterization of these crystals is often limited to techniques such as grazing incidence small-angle scattering that provide only global structural information and also often require synchrotron sources. Here we demonstrate small-angle Bragg scattering from nanostructured materials using a tabletop-scale setup based on high-harmonic generation, to reveal important information about the local order of nanosphere grains, separated by grain boundaries and discontinuities. We also apply full-field quantitative ptychographic imaging to visualize the extended structure of a silica close-packed nanosphere multilayer, with thickness information encoded in the phase. These combined techniques allow us to simultaneously characterize the silica nanospheres size, their symmetry and distribution within single colloidal crystal grains, the local arrangement of nearest-neighbor grains, as well as to quantitatively determine the number of layers within the sample. Key to this advance is the good match between the high harmonic wavelength used (13.5nm) and the high transmission, high scattering efficiency, and low sample damage of the silica colloidal crystal at this wavelength. As a result, the relevant distances in the sample - namely, the interparticle distance (≈124nm) and the colloidal grains local arrangement (≈1µm) - can be investigated with Bragg coherent EUV scatterometry and ptychographic imaging within the same experiment simply by tuning the EUV spot size at the sample plane (5µm and 15µm respectively). In addition, the high spatial coherence of high harmonics light, combined with advances in imaging techniques, makes it possible to image near-periodic structures quantitatively and nondestructively, and enables the observation of the extended order of quasi-periodic colloidal crystals, with a spatial resolution better than 20nm. In the future, by harnessing the high time-resolution of tabletop high harmonics, this technique can be extended to dynamically image the three-dimensional electronic, magnetic, and transport properties of functional nanosystems.

Chylothorax and pleural effusion in contemporary extracardiac fenestrated fontan completion.

BACKGROUND: We hypothesized that chylothorax could be a sign of intolerance to the Fontan physiology, and thus patients who develop chylothorax or pleural effusion have worse medium-term to long-term survival. METHODS: A total of 324 patients who underwent the Fontan operation between 2000 and 2013 were included. Chylothorax was defined as ≥5 mL/kg/day of chylomicron-positive chest drainage fluid no earlier than postoperative day 5 or drainage with >80% lymphocytes. Outcomes were compared between the chylothorax and non-chylothorax groups by the Kaplan-Meier method and log-rank test. Independent predictors of chylothorax and number of days of any chest drainage were analyzed with multivariable logistic regression and multivariable generalized negative binomial regression for count data, respectively. RESULTS: Chylothorax occurred in 78 patients (24%). Compared with the non-chylothorax group, the chylothorax group had a longer duration of chest tube requirement (median, 18 days vs 9 days; P < .000) and a longer length of hospital stay (median, 19 days vs 10 days; P < .000). Eight patients (10.3%) required thoracic duct ligation. The chylothorax group had lower freedom from death (P = .013) and from composite adverse events (P = .021). No predictor was found for chylothorax. Pulmonary atresia (P = .031) and pre-Fontan pulmonary artery pressure (P = .01) were predictive of prolonged pleural effusion (>14 days). CONCLUSIONS: Occurrence of chylothorax following the Fontan operation can be a marker of poorer medium-term clinical outcomes. It is difficult to predict occurrence of chylothorax owing to its multifactorial nature and involvement of lymphatic compensatory capacity that is unmasked only after the Fontan operation.

Confined Chemical Fluid Deposition of Ferromagnetic Metalattices.

A magnetic, metallic inverse opal fabricated by infiltration into a silica nanosphere template assembled from spheres with diameters less than 100 nm is an archetypal example of a "metalattice". In traditional quantum confined structures such as dots, wires, and thin films, the physical dynamics in the free dimensions is typically largely decoupled from the behavior in the confining directions. In a metalattice, the confined and extended degrees of freedom cannot be separated. Modeling predicts that magnetic metalattices should exhibit multiple topologically distinct magnetic phases separated by sharp transitions in their hysteresis curves as their spatial dimensions become comparable to and smaller than the magnetic exchange length, potentially enabling an interesting class of "spin-engineered" magnetic materials. The challenge to synthesizing magnetic inverse opal metalattices from templates assembled from sub-100 nm spheres is in infiltrating the nanoscale, tortuous voids between the nanospheres void-free with a suitable magnetic material. Chemical fluid deposition from supercritical carbon dioxide could be a viable approach to void-free infiltration of magnetic metals in view of the ability of supercritical fluids to penetrate small void spaces. However, we find that conventional chemical fluid deposition of the magnetic late transition metal nickel into sub-100 nm silica sphere templates in conventional macroscale reactors produces a film on top of the template that appears to largely block infiltration. Other deposition approaches also face difficulties in void-free infiltration into such small nanoscale templates or require conducting substrates that may interfere with properties measurements. Here we report that introduction of "spatial confinement" into the chemical fluid reactor allows for fabrication of nearly void-free nickel metalattices by infiltration into templates with sphere sizes from 14 to 100 nm. Magnetic measurements suggest that these nickel metalattices behave as interconnected systems rather than as isolated superparamagnetic systems coupled solely by dipolar interactions.

Double Replication of Silica Colloidal Crystal Films.

Inverse opals made by polymerizing vinyl monomers inside a colloidal crystal have lattice dimensions that are contracted relative to the original hard template. This effect was studied in order to investigate the possibility of making double replicas of varying pore sizes from different materials, and to gain a better understanding of the polymer contraction behavior during replication. The degree of lattice contraction was measured using colloidal crystal films formed from silica spheres with diameters in the range 33-225 nm, and polymers pEDMA [poly(1,2-ethanediol dimethacrylate)], pDVB [poly(divinylbenzene)], pHDMA [poly(1,6-hexanediol dimethacrylate)], pBDMA [poly(1,4-butanediol dimethacrylate)], and a 5:4 copolymer mixture of pEDMA/pDVB. The degree of lattice contraction depended on the alkyl chain length of the monomer, as well as the degree of cross-linking, with up to 32% contraction observed for pEDMA when the silica template was removed. However, filling the polymer inverse opals with silica or titania returned the lattice spacing closer to its original size, an effect that can be rationalized in terms of the driving forces for contraction. Double replication of both single-component and binary silica colloidal crystals therefore generated silica and titania replicas of the original lattice. Thus, double replication provides a pathway for accessing periodic structures that are difficult to synthesize directly from materials such as titania.

Binary Colloidal Crystal Films Grown by Vertical Evaporation of Silica Nanoparticle Suspensions.

Despite intensive research efforts in the synthesis of binary colloidal crystals, the production of well ordered binary colloidal crystal films over large areas continues to be synthetically challenging. In this paper, we investigate the phase behavior of binary mixtures of l-arginine-stabilized 36 and 22 nm silica nanoparticles deposited as centimeter-scale thin films onto a vertical substrate via evaporative assembly. By adjusting the temperature and relative colloid composition under high humidity conditions, we controlled the order of the resultant colloidal crystal films. The domain size of the AB2 binary crystalline phase increased with an excess of small (B) particles and a very slow evaporation rate below 45 °C, with the best results obtained at 30° and 35 °C.

The Utility of Cardiopulmonary Exercise Testing for the Prediction of Outcomes in Ambulatory Children With Dilated Cardiomyopathy.

BACKGROUND: Unlike adult patients, the utility of cardiopulmonary exercise testing (CPET) in children as a prognostic tool is unclear. We sought to examine the associations of CPET with outcomes in children with dilated cardiomyopathy (DCM). METHODS: This was a single-center, retrospective review of children with DCM who underwent CPET. The primary endpoint for this study was a time-dependent composite outcome of hospitalization for management of decompensated heart failure, initiation of mechanical circulatory support, heart transplant, or death. RESULTS: We examined 52 children with DCM who underwent CPET at median age 12.6 years (interquartile range [IQR], 9.9-14.6 years). At first CPET, the median peak heart rate was 80% (IQR, 70-88%) of predicted, median peak oxygen consumption 62% (IQR, 45-77%) of predicted, and median minute ventilation/carbon dioxide production slope 34.9 (IQR, 27.9-39.4). Eighteen (35%) patients reached the composite outcome during follow-up. Univariable factors associated with the composite outcome included: lower peak heart rate predicted, lower blood pressure response, lower peak oxygen consumption predicted, and higher minute ventilation/carbon dioxide production slope. The association between exercise performance and composite outcome was linear; thus, no reliable cutoff point could be identified. Serial CPET had been performed in 30 patients; clinically, those with deterioration of exercise capacity had poorer outcomes. CONCLUSIONS: Cardiopulmonary exercise testing is feasible in children with DCM and is useful to predict outcomes. The finding of lower exercise capacity and lower blood pressure response should prompt closer follow-up. In those with serial testing, a decline in exercise capacity may be a marker of clinical deterioration.

Canadian Cardiovascular Society/Canadian Pediatric Cardiology Association Position Statement on Pulse Oximetry Screening in Newborns to Enhance Detection of Critical Congenital Heart Disease.

Congenital heart disease is the most common congenital malformation and approximately 3 in 1000 newborns have critical congenital heart disease (CCHD). Timely diagnosis affects morbidity, mortality, and disability, and newborn pulse oximetry screening has been studied to enhance detection of CCHD. In this position statement we present an evaluation of the literature for pulse oximetry screening. Current detection strategies including prenatal ultrasound examination and newborn physical examination are limited by low diagnostic sensitivity. Pulse oximetry screening is safe, noninvasive, easy to perform, and widely available with a high specificity (99.9%) and moderately high sensitivity (76.5%). When an abnormal saturation is obtained, the likelihood of having CCHD is 5.5 times greater than when a normal result is obtained. The use of pulse oximetry combined with current strategies has shown sensitivities of up to 92% for detecting CCHD. False positive results can be minimized by screening after 24 hours, and testing the right hand and either foot might further increase sensitivity. Newborns with abnormal screening results should undergo a comprehensive assessment and echocardiography performed if a cardiac cause cannot be excluded. Screening has been studied to be cost neutral to cost effective. We recommend that pulse oximetry screening should be routinely performed in all healthy newborns to enhance the detection of CCHD in Canada.