Attempting to Acutely Manipulate Ground Contact Time Imbalances Impairs Running Economy

Running economy (RE) is a key performance determinant. Biomechanical markers have been linked to RE, including ground contact time (GCT), cadence, and vertical oscillation (VO). Recently, we showed a strong relationship between GCT imbalances and RE. Because these markers can be tracked real-time with consumer-wearable devices, runners now have access to instant feedback concerning their mechanics. PURPOSE: Determine if attempting to correct GCT imbalances real-time alters mechanics and RE. METHODS: 7 recreational runners (38 ± 15 years, 24.7 ± 2.8 kg/m2, 5 male) completed 2, 10-minute running trials (9.65 km/hr) on separate days. For both trials, subjects ran with a heart rate (HR) monitor/watch that measured GCT, GCT imbalances, cadence, and VO. For the control (CT) trial, subjects were not permitted to receive feedback from the watch. During the feedback (FB) trial, the watch was set to display GCT imbalances, and subjects were prompted every 20-30 seconds to monitor/attempt to correct any imbalances. Both trials were preceded by a dynamic warmup and 5-minute jog. For the FB trial warmup, subjects were acclimated to the watch and allowed to experiment with manipulating their GCT imbalances. VO2 was monitored continuously throughout each 10-minute trial, and average values from 6 to 9 minutes were determined for each trial. Average values for all running biomechanical variables were calculated from 0.5 minutes to 9.5 minutes. Comparisons between trials were made with a dependent sample t-test. RESULTS: The FB trial elicited a significantly higher (p = .011) working VO2 (35.5 ± 1.6 ml/kg/min) compared to the CT trial (33.4 ± 1.8 ml/kg/min). There were no other significant differences between trials for the other measured variables. Average values for each variable by trial were as follows: RER (CT: .91 ± .04; FB: .92 ± .05), HR (CT: 159 ± 26 bpm; FB: 163 ± 24 bpm), GCT % difference (CT: 1.69 ± .67%; FB: 1.70 ± 1.70%), GCT absolute difference (CT: 9 ± 3 ms; FB: 8 ± 7 ms), GCT (CT: 272 ± 26 ms; FB: 268 ± 31 ms), Cadence (CT: 165 ± 9 steps/min; FB: 167 ± 9 steps/min); VO (CT: 9.3 ± 2.0 cm; FB: 9.2 ± 1.9 cm), VO ratio (CT: 9.5 ± 1.6 cm/m; FB: 9.5 ± 1.6 cm/m). CONCLUSIONS: Acutely attempting to correct GCT imbalances did not result in improved mechanics and actually impaired RE. Altering mechanics based on real-time feedback from consumer-wearable devices may impair performance in the short term. Given that GCT imbalances have been linked to impaired RE, future research should determine how to better correct these imbalances rather than attempting to acutely manipulate them

Regulating global capital flows for long-run development

This repository item contains a single issue of the Pardee Center Task Force Reports, a publication series that began publishing in 2009 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future. The Task Force was co-sponsored by the BU Pardee Center, the Initiative for Policy Dialogue at Columbia University, and the Global Development and Environment Institute at Tufts University, and it met at Boston University in September 2011. The Task Force Co-Chairs authored an Issues In Brief on this subject in November 2011 published by the Pardee Center.This report is the product of the Pardee Center Task Force on Regulating Global Capital Flows for Long-Run Development convened in September 2011 on behalf of the Pardee Center’s Global Economic Governance Initiative led by Kevin P. Gallagher, Associate Professor of International Relations at Boston University. Gallagher co-chaired the Task Force along with Stephany Griffith-Jones and José Antonio Ocampo of the Initiative for Policy Dialogue (IPD) at Columbia University. With contributions from a dozen prominent scholars and practitioners in the field of global finance and development, the report is intended to contribute expert knowledge to an important and very timely debate concerning whether and how nations can use what have been traditionally referred to as capital controls (classified in the report as ‘capital account regulations’ or CARs) to prevent and mitigate financial crises caused by short-term speculative capital flows in developing countries. Based on discussions among members at the September 2011 meeting, the report posits that there is a clear rationale for capital account regulations in the wake of the 2008 financial crisis, that the design and monitoring of such regulations is essential for their effectiveness, and that a limited amount of global and regional cooperation would be useful to ensure that CARs can form an effective part of the macroeconomic policy toolkit. The protocol for deploying capital account regulations in developing countries that is put forth here stands in stark contrast to a set of guidelines for the use of capital controls endorsed by the board of the International Monetary Fund (IMF) in March 2011. However the Task Force’s recommendations are more in sync with the set of “coherent conclusions” on capital account regulations endorsed by the G-20 in November 2011. Our hope is that this Pardee Center Task Force Report will help inform the discussions and decisions of policymakers and the IMF as they move forward on this issue under the rubric of the G-20 recommendations

Porous Media Matric Potential and Water Content Measurements During Parabolic Flight

Control of water and air in the root zone of plants remains a challenge in the microgravity environment of space. Due to limited flight opportunities, research aimed at resolving microgravity porous media fluid dynamics must often be conducted on Earth. The NASA KC-135 reduced gravity flight program offers an opportunity for Earth-based researchers to study physical processes in a variable gravity environment. The objectives of this study were to obtain measurements of water content and matric potential during the parabolic profile flown by the KC-135 aircraft. The flight profile provided 20–25 s of microgravity at the top of the parabola, while pulling 1.8 g at the bottom. The soil moisture sensors (Temperature and Moisture Acquisition System: Orbital Technologies, Madison, WI) used a heat-pulse method to indirectly estimate water content from heat dissipation. Tensiometers were constructed using a stainless steel porous cup with a pressure transducer and were used to measure the matric potential of the medium. The two types of sensors were placed at different depths in a substrate compartment filled with 1–2 mm Turface (calcined clay). The ability of the heat-pulse sensors to monitor overall changes in water content in the substrate compartment decreased with water content. Differences in measured water content data recorded at 0, 1, and 1.8 g were not significant. Tensiometer readings tracked pressure differences due to the hydrostatic force changes with variable gravity. The readings may have been affected by changes in cabin air pressure that occurred during each parabola. Tensiometer porous membrane conductivity (function of pore size) and fluid volume both influence response time. Porous media sample height and water content influence time-to-equilibrium, where shorter samples and higher water content achieve faster equilibrium. Further testing is needed to develop these sensors for space flight applications

Similar ultrafast dynamics of several dissimilar Dirac and Weyl semimetals

Recent years have seen the rapid discovery of solids whose low-energy electrons have a massless, linear dispersion, such as Weyl, line-node, and Dirac semimetals. The remarkable optical properties predicted in these materials show their versatile potential for optoelectronic uses. However, little is known of their response in the picoseconds after absorbing a photon. Here we measure the ultrafast dynamics of four materials that share non-trivial band structure topology but that differ chemically, structurally, and in their low-energy band structures: ZrSiS, which hosts a Dirac line node and Dirac points; TaAs and NbP, which are Weyl semimetals; and Sr$_{1-y}$Mn$_{1-z}$Sb$_2$, in which Dirac fermions coexist with broken time-reversal symmetry. After photoexcitation by a short pulse, all four relax in two stages, first sub-picosecond, and then few-picosecond. Their rapid relaxation suggests that these and related materials may be suited for optical switches and fast infrared detectors. The complex change of refractive index shows that photoexcited carrier populations persist for a few picoseconds

Surface Heat Fluxes Drive a Two‐Phase Response in Southern Ocean Mode Water Stratification

AbstractSubantarctic mode waters have low stratification and are formed through subduction from thick winter mixed layers in the Southern Ocean. To investigate how surface forcing affects the stratification in mode water formation regions in the Southern Ocean, a set of adjoint sensitivity experiments are conducted. The objective function is the annual‐average stratification over the mode water formation region, which is evaluated from potential temperature and salinity adjoint sensitivity experiments. The analysis of impacts, from the product of sensitivities and forcing variability, identifies the separate effects of the wind stress, heat flux, and freshwater flux, revealing that the dominant control on stratification is from surface heat fluxes, as well as a smaller effect from zonal wind stress. The adjoint sensitivities of stratification to surface heat flux reveal a surprising change in sign over 2 years lead time: surface cooling leads to the expected initial local decrease in stratification, but there is a delayed response leading to an increase in stratification. This delayed response in stratification involves effective atmospheric damping of the surface thermal contribution, so that eventually the oppositely‐signed advective haline contribution dominates. This two‐phase response of stratification is found to hold over mode water formation regions in the South Indian and Southeast Pacific sectors of the Southern Ocean, where there are strong advective flows linked to the Antarctic Circumpolar Current.</jats:p

Changes in lipid levels and incidence of cardiovascular events following tofacitinib treatment in patients with psoriatic arthritis: a pooled analysis acrossphase III and long‐term extension studies

Objective: The risk of cardiovascular disease (CVD) is higher in patients with psoriatic arthritis (PsA) compared to the general population. Tofacitinib is an oral Janus kinase inhibitor for the treatment of PsA. Because tofacitinib increases circulating lipid levels in some patients, we evaluated CVD risk factors and major adverse cardiovascular events (MACE) in patients with active PsA receiving tofacitinib 5 or 10 mg twice daily plus conventional synthetic disease‐modifying antirheumatic drugs. Methods: Data were pooled from 2 phase III studies (Efficacy and Safety of Tofacitinib in Psoriatic Arthritis [OPAL Broaden] and Tofacitinib in Patients with Psoriatic Arthritis With Inadequate Response to TNF Inhibitors [OPAL Beyond]) and 1 ongoing long‐term extension (Open‐Label Extension Study of Tofacitinib in Psoriatic Arthritis [OPAL Balance], data cutoff January 2017; database not locked). Outcomes included fasting lipid levels, blood pressure, hypertension‐related adverse events (AEs; including hypertension, high blood pressure, and increased blood pressure), and MACE. Results: Overall, 783 tofacitinib‐treated patients were included. Percentage increases from baseline in low‐density lipoprotein cholesterol (LDL‐c) and high‐density lipoprotein cholesterol (HDL‐c) levels ranged from 9% to 14% for tofacitinib 5 mg and 10 mg at 3 and 6 months; no meaningful changes in LDL‐c:HDL‐c or total cholesterol:HDL‐c ratios were observed. Blood pressure remained stable for 24 months. Fifty‐eight patients (7.4%) had hypertension‐related AEs; none were fatal (incidence rate [IR] per 100 patient‐years 4.81 [95% confidence interval (95% CI) 3.65–6.22]). Five patients (0.6%) had MACE (IR 0.24 [95% CI 0.05–0.70]); 2 were fatal. Conclusion: Serum lipid level increases at month 3 following tofacitinib treatment in PsA were consistent with observations in rheumatoid arthritis and psoriasis. The IR of hypertension‐related AEs and MACE was low; long‐term follow‐up is ongoing

The Brazilian Tunable Filter Imager for the SOAR telescope

This paper presents a new Tunable Filter Instrument for the SOAR telescope. The Brazilian Tunable Filter Imager (BTFI) is a versatile, new technology, tunable optical imager to be used in seeing-limited mode and at higher spatial fidelity using the SAM Ground-Layer Adaptive Optics facility at the SOAR telescope. The instrument opens important new science capabilities for the SOAR community, from studies of the centers of nearby galaxies and the insterstellar medium to statistical cosmological investigations. The BTFI takes advantage of three new technologies. The imaging Bragg Tunable Filter concept utilizes Volume Phase Holographic Gratings in a double-pass configuration, as a tunable filter, while a new Fabry-Perot (FP) concept involves technologies which allow a single FP etalon to act over a large range of interference orders and spectral resolutions. Both technologies will be in the same instrument. Spectral resolutions spanning the range between 25 and 30,000 can be achieved through the use of iBTF at low resolution and scanning FPs beyond R ~2,000. The third new technologies in BTFI is the use of EMCCDs for rapid and cyclically wavelength scanning thus mitigating the damaging effect of atmospheric variability through data acquisition. An additional important feature of the instrument is that it has two optical channels which allow for the simultaneous recording of the narrow-band, filtered image with the remaining (complementary) broad-band light. This avoids the uncertainties inherent in tunable filter imaging using a single detector. The system was designed to supply tunable filter imaging with a field-of-view of 3 arcmin on a side, sampled at 0.12" for direct Nasmyth seeing-limited area spectroscopy and for SAM's visitor instrument port for GLAO-fed area spectroscopy. The instrument has seen first light, as a SOAR visitor instrument. It is now in comissioning phase.Comment: accepted in PAS

Obtaining cross-sections of paint layers in cultural artifacts using femtosecond pulsed lasers

Recently, ultrafast lasers exhibiting high peak powers and extremely short pulse durations have created a new paradigm in materials processing. The precision and minimal thermal damage provided by ultrafast lasers in the machining of metals and dielectrics also suggests a novel application in obtaining precise cross-sections of fragile, combustible paint layers in artwork and cultural heritage property. Cross-sections of paint and other decorative layers on artwork provide critical information into its history and authenticity. However, the current methodology which uses a scalpel to obtain a cross-section can cause further damage, including crumbling, delamination, and paint compression. Here, we demonstrate the ability to make controlled cross-sections of paint layers with a femtosecond pulsed laser, with minimal damage to the surrounding artwork. The femtosecond laser cutting overcomes challenges such as fragile paint disintegrating under scalpel pressure, or oxidation by the continuous-wave (CW) laser. Variations in laser power and translational speed of the laser while cutting exhibit different benefits for cross-section sampling. The use of femtosecond lasers in studying artwork also presents new possibilities in analyzing, sampling, and cleaning of artwork with minimal destructive effects