An Exploratory Approach to Manipulating Dynamic Stability: Investigating the Role of Visual Control during a Precision Foot Placement Task

ABSTRACT Background: The visual system provides the body with an accurate sensory system; designed to gather information at a distance and acts as a feedforward control mechanism during human locomotion. By doing so, visual information contributes coordination of the head-arm-trunk (HAT) segment and modulating foot placement. The purpose of this study was to examine the effects of a constrained pathway during a complex navigational stone-stepping task on HAT segment control and how the visual system guides locomotion during a complex foot placement task. Methods: Nine university-aged females (Mean age: 22.5 years old +/-1.75) participated in this study. Participants were instrumented with four rigid bodies (4x3 IRED markers) on the head, trunk and feet and two IRED markers on the wrists in order to measure kinematic data, collected by Optotrak system (NDI, Waterloo, Canada). Additionally, each participant was outfitted with an ASL H7-HS High Speed Head Mounted Optics (ASL, Bedford, USA) eye tracking unit to assess gaze behaviours. The experimental protocol required participants to perform 40 walking trials across four conditions (i.e., constrained and self-selected pathways; starting with either the left or the right foot), on a 7.2m x 1.2m raised-target platform. The platform consisted of 60 sloper-style rock climbing holds, whose location was designed to satisfy one of three criterion: 1) in line with natural footfall locations (e.g. normal step length and/or width dimensions of 60cm by 10cm); 2) greater or less than one of the dimensions of a natural step length or width; or 3) to act as a possible option/distractor on the pathway. The two constrained pathways were indicated with a high-contrasting moldable material placed inside each hold’s screw hole. Measurements were compared across conditions (i.e., constrained versus unconstrained), time points (e.g. first, middle, and last trial performed of each condition), and segment (Segment 1: first 3m of path or Segment 2: last 3m of path). The measurements included: horizontal and vertical pupil velocity RMS; average walking speed; trunk rotations about the hip (i.e., pitch and roll), and whole-body movement (i.e., ML COM variability). Results: Findings revealed that there was a significant difference between conditions such that: 1) the constrained vertical pupil RMS velocity was higher than the unconstrained (F(3,24)=4.71; p= .04; d=.46); 2) the unconstrained horizontal pupil RMS velocity was higher than the unconstrained (F(3,24)=4.40; p= .03; d=.36); 3) the constrained average walking speed was greater than the unconstrained (F(3,24)=23.27; p=0.04; d=.30); 4) the constrained trunk roll was greater than the unconstrained (F(3,21)=4.84; p=0.01; d=.45); and 5) the unconstrained dynamic stability margin minimum (DSMmin) was greater than the constrained (F(3,21)=4.89; p= .01; d=.41). Conclusions: The complex nature of the raised-target foot placement task challenged individuals from the start of each condition, forcing participants to learn how to control body movements—especially in the AP direction. During constrained condition, there was evidence to suggest that there was a greater regulation of trunk control than during unconstrained trials. This was attributed to the conditional demands of predetermined pathway to follow. However, during unconstrained trials, individuals were able to choose footholds, which were most likely based on their current state of stability. And thus, conditional demands of the pathway influenced gaze behaviours, such that during the constrained condition participants used a scanning behaviour (i.e., greater vertical pupil velocity RMS) whereas participants used more of a sampling behaviour (i.e., greater horizontal and slower vertical pupil velocities) during the free choice pathway condition. Therefore, the finding from this study suggest that gaze behaviours are influenced by stepping characteristics and these different gaze behaviours have different effects on trunk control

An Exploratory Approach to Manipulating Dynamic Stability: Investigating the Role of Visual Control during a Precision Foot Placement Task

ABSTRACT Background: The visual system provides the body with an accurate sensory system; designed to gather information at a distance and acts as a feedforward control mechanism during human locomotion. By doing so, visual information contributes coordination of the head-arm-trunk (HAT) segment and modulating foot placement. The purpose of this study was to examine the effects of a constrained pathway during a complex navigational stone-stepping task on HAT segment control and how the visual system guides locomotion during a complex foot placement task. Methods: Nine university-aged females (Mean age: 22.5 years old +/-1.75) participated in this study. Participants were instrumented with four rigid bodies (4x3 IRED markers) on the head, trunk and feet and two IRED markers on the wrists in order to measure kinematic data, collected by Optotrak system (NDI, Waterloo, Canada). Additionally, each participant was outfitted with an ASL H7-HS High Speed Head Mounted Optics (ASL, Bedford, USA) eye tracking unit to assess gaze behaviours. The experimental protocol required participants to perform 40 walking trials across four conditions (i.e., constrained and self-selected pathways; starting with either the left or the right foot), on a 7.2m x 1.2m raised-target platform. The platform consisted of 60 sloper-style rock climbing holds, whose location was designed to satisfy one of three criterion: 1) in line with natural footfall locations (e.g. normal step length and/or width dimensions of 60cm by 10cm); 2) greater or less than one of the dimensions of a natural step length or width; or 3) to act as a possible option/distractor on the pathway. The two constrained pathways were indicated with a high-contrasting moldable material placed inside each hold’s screw hole. Measurements were compared across conditions (i.e., constrained versus unconstrained), time points (e.g. first, middle, and last trial performed of each condition), and segment (Segment 1: first 3m of path or Segment 2: last 3m of path). The measurements included: horizontal and vertical pupil velocity RMS; average walking speed; trunk rotations about the hip (i.e., pitch and roll), and whole-body movement (i.e., ML COM variability). Results: Findings revealed that there was a significant difference between conditions such that: 1) the constrained vertical pupil RMS velocity was higher than the unconstrained (F(3,24)=4.71; p= .04; d=.46); 2) the unconstrained horizontal pupil RMS velocity was higher than the unconstrained (F(3,24)=4.40; p= .03; d=.36); 3) the constrained average walking speed was greater than the unconstrained (F(3,24)=23.27; p=0.04; d=.30); 4) the constrained trunk roll was greater than the unconstrained (F(3,21)=4.84; p=0.01; d=.45); and 5) the unconstrained dynamic stability margin minimum (DSMmin) was greater than the constrained (F(3,21)=4.89; p= .01; d=.41). Conclusions: The complex nature of the raised-target foot placement task challenged individuals from the start of each condition, forcing participants to learn how to control body movements—especially in the AP direction. During constrained condition, there was evidence to suggest that there was a greater regulation of trunk control than during unconstrained trials. This was attributed to the conditional demands of predetermined pathway to follow. However, during unconstrained trials, individuals were able to choose footholds, which were most likely based on their current state of stability. And thus, conditional demands of the pathway influenced gaze behaviours, such that during the constrained condition participants used a scanning behaviour (i.e., greater vertical pupil velocity RMS) whereas participants used more of a sampling behaviour (i.e., greater horizontal and slower vertical pupil velocities) during the free choice pathway condition. Therefore, the finding from this study suggest that gaze behaviours are influenced by stepping characteristics and these different gaze behaviours have different effects on trunk control

A canadian field test of finnish ayrshires: growth and reproductive performance

International audienc

International standards for fetal growth based on serial ultrasound measurements: the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project

Background: In 2006, WHO produced international growth standards for infants and children up to age 5 years on the basis of recommendations from a WHO expert committee. Using the same methods and conceptual approach, the Fetal Growth Longitudinal Study (FGLS), part of the INTERGROWTH-21st Project, aimed to develop international growth and size standards for fetuses. Methods: The multicentre, population-based FGLS assessed fetal growth in geographically defined urban populations in eight countries, in which most of the health and nutritional needs of mothers were met and adequate antenatal care was provided. We used ultrasound to take fetal anthropometric measurements prospectively from 14 weeks and 0 days of gestation until birth in a cohort of women with adequate health and nutritional status who were at low risk of intrauterine growth restriction. All women had a reliable estimate of gestational age confirmed by ultrasound measurement of fetal crown–rump length in the first trimester. The five primary ultrasound measures of fetal growth—head circumference, biparietal diameter, occipitofrontal diameter, abdominal circumference, and femur length—were obtained every 5 weeks (within 1 week either side) from 14 weeks to 42 weeks of gestation. The best fitting curves for the five measures were selected using second-degree fractional polynomials and further modelled in a multilevel framework to account for the longitudinal design of the study. Findings: We screened 13 108 women commencing antenatal care at less than 14 weeks and 0 days of gestation, of whom 4607 (35%) were eligible. 4321 (94%) eligible women had pregnancies without major complications and delivered live singletons without congenital malformations (the analysis population). We documented very low maternal and perinatal mortality and morbidity, confirming that the participants were at low risk of adverse outcomes. For each of the five fetal growth measures, the mean differences between the observed and smoothed centiles for the 3rd, 50th, and 97th centiles, respectively, were small: 2·25 mm (SD 3·0), 0·02 mm (3·0), and −2·69 mm (3·2) for head circumference; 0·83 mm (0·9), −0·05 mm (0·8), and −0·84 mm (1·0) for biparietal diameter; 0·63 mm (1·2), 0·04 mm (1·1), and −1·05 mm (1·3) for occipitofrontal diameter; 2·99 mm (3·1), 0·25 mm (3·2), and −4·22 mm (3·7) for abdominal circumference; and 0·62 mm (0·8), 0·03 mm (0·8), and −0·65 mm (0·8) for femur length. We calculated the 3rd, 5th 10th, 50th, 90th, 95th and 97th centile curves according to gestational age for these ultrasound measures, representing the international standards for fetal growth. Interpretation: We recommend these international fetal growth standards for the clinical interpretation of routinely taken ultrasound measurements and for comparisons across populations. Funding: Bill & Melinda Gates Foundation

On effective actions of BPS branes and their higher derivative corrections

We calculate in detail the disk level S-matrix element of one Ramond-Ramond field and three gauge field vertex operators in the world volume of BPS branes, to find four gauge field couplings to all orders of $\alpha'$ up to on-shell ambiguity. Then using these infinite couplings we find that the massless pole of the field theory amplitude is exactly equal to the massless pole S-matrix element of this amplitude for the $p=n$ case to all orders of $\alpha'$. Finally we show that the infinite massless poles and the contact terms of this amplitude for the $p=n+2$ case can be reproduced by the Born-Infeld action and the Wess-Zumino actions and by their higher derivative corrections.Comment: 26 pages, 2 figures, minor corrections,references added and version published in JHE

Poly(ADP-ribose) polymerase family member 14 (PARP14) is a novel effector of the JNK2-dependent pro-survival signal in multiple myeloma

Copyright @ 2013 Macmillan Publishers Limited. This is the author's accepted manuscript. The final published article is available from the link below.Regulation of cell survival is a key part of the pathogenesis of multiple myeloma (MM). Jun N-terminal kinase (JNK) signaling has been implicated in MM pathogenesis, but its function is unclear. To elucidate the role of JNK in MM, we evaluated the specific functions of the two major JNK proteins, JNK1 and JNK2. We show here that JNK2 is constitutively activated in a panel of MM cell lines and primary tumors. Using loss-of-function studies, we demonstrate that JNK2 is required for the survival of myeloma cells and constitutively suppresses JNK1-mediated apoptosis by affecting expression of poly(ADP-ribose) polymerase (PARP)14, a key regulator of B-cell survival. Strikingly, we found that PARP14 is highly expressed in myeloma plasma cells and associated with disease progression and poor survival. Overexpression of PARP14 completely rescued myeloma cells from apoptosis induced by JNK2 knockdown, indicating that PARP14 is critically involved in JNK2-dependent survival. Mechanistically, PARP14 was found to promote the survival of myeloma cells by binding and inhibiting JNK1. Moreover, inhibition of PARP14 enhances the sensitization of MM cells to anti-myeloma agents. Our findings reveal a novel regulatory pathway in myeloma cells through which JNK2 signals cell survival via PARP14, and identify PARP14 as a potential therapeutic target in myeloma.Kay Kendall Leukemia Fund, NIH, Cancer Research UK, Italian Association for Cancer Research and the Foundation for Liver Research

Ultrasound-based gestational-age estimation in late pregnancy.

OBJECTIVE: Accurate gestational-age (GA) estimation, preferably by ultrasound measurement of fetal crown-rump length before 14 weeks' gestation, is an important component of high-quality antenatal care. The objective of this study was to determine how GA can best be estimated by fetal ultrasound for women who present for the first time late in pregnancy with uncertain or unknown menstrual dates. METHODS: INTERGROWTH-21(st) was a large, prospective, multicenter, population-based project performed in eight geographically defined urban populations. One of its principal components, the Fetal Growth Longitudinal Study, aimed to develop international fetal growth standards. Each participant had their certain menstrual dates confirmed by first-trimester ultrasound examination. Fetal head circumference (HC), biparietal diameter (BPD), occipitofrontal diameter (OFD), abdominal circumference (AC) and femur length (FL) were measured every 5 weeks from 14 weeks' gestation until delivery. For each participant, a single, randomly selected ultrasound examination was used to explore all candidate biometric variables and permutations to build models to predict GA. Regression equations were ranked based upon minimization of the mean prediction error, goodness of fit and model complexity. An automated machine learning algorithm, the Genetic Algorithm, was adapted to evaluate > 64 000 potential polynomial equations as predictors. RESULTS: Of the 4607 eligible women, 4321 (94%) had a pregnancy without major complications and delivered a live singleton without congenital malformations. After other exclusions (missing measurements in GA window and outliers), the final sample comprised 4229 women. Two skeletal measures, HC and FL, produced the best GA prediction, given by the equation loge (GA) = 0.03243 × (loge (HC))(2) + 0.001644 × FL × loge (HC) + 3.813. When FL was not available, the best equation based on HC alone was loge (GA) = 0.05970 × (loge (HC))(2) + 0.000000006409 × (HC)(3) + 3.3258. The estimated uncertainty of GA prediction (half width 95% interval) was 6-7 days at 14 weeks' gestation, 12-14 days at 26 weeks' gestation and > 14 days in the third trimester. The addition of FL to the HC model led to improved prediction intervals compared with using HC alone, but no further improvement in prediction was afforded by adding AC, BPD or OFD. Equations that included other measurements (BPD, OFD and AC) did not perform better. CONCLUSIONS: Among women initiating antenatal care late in pregnancy, a single set of ultrasound measurements combining HC and FL in the second trimester can be used to estimate GA with reasonable accuracy. We recommend this tool for underserved populations but considerable efforts should be implemented to improve early initiation of antenatal care worldwide. © 2016 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology

Effects of American ginseng (Panax quinquefolius) on neurocognitive function: an acute, randomised, double-blind, placebo-controlled, crossover study

Over the last decade, Asian ginseng (Panax ginseng) has been shown to improve aspects of human cognitive function. American ginseng (Panax quinquefolius) has a distinct ginsenoside profile from P. ginseng, promising cognitive enhancing properties in preclinical studies and benefits processes linked to human cognition. The availability of a highly standardised extract of P. quinquefolius (Cereboost (TM)) led us to evaluate its neurocognitive properties in humans for the first time. This randomised, double-blind, placebo-controlled, crossover trial (N = 32, healthy young adults) assessed the acute mood, neurocognitive and glycaemic effects of three doses (100, 200 400 mg) of Cereboost (TM) (P. quinquefolius standardised to 10.65% ginsenosides). Participants' mood, cognitive function and blood glucose were measured 1, 3 and 6 h following administration. There was a significant improvement of working memory (WM) performance associated with P. quinquefolius. Corsi block performance was improved by all doses at all testing times. There were differential effects of all doses on other WM tasks which were maintained across the testing day. Choice reaction time accuracy and 'calmness' were significantly improved by 100 mg. There were no changes in blood glucose levels. This preliminary study has identified robust working memory enhancement following administration of American ginseng. These effects are distinct from those of Asian ginseng and suggest that psychopharmacological properties depend critically on ginsenoside profiles. These results have ramifications for the psychopharmacology of herbal extracts and merit further study using different dosing regimens and in populations where cognition is fragile

Composite GUTs: models and expectations at the LHC

We investigate grand unified theories (GUTs) in scenarios where electroweak (EW) symmetry breaking is triggered by a light composite Higgs, arising as a Nambu-Goldstone boson from a strongly interacting sector. The evolution of the standard model (SM) gauge couplings can be predicted at leading order, if the global symmetry of the composite sector is a simple group G that contains the SM gauge group. It was noticed that, if the right-handed top quark is also composite, precision gauge unification can be achieved. We build minimal consistent models for a composite sector with these properties, thus demonstrating how composite GUTs may represent an alternative to supersymmetric GUTs. Taking into account the new contributions to the EW precision parameters, we compute the Higgs effective potential and prove that it realizes consistently EW symmetry breaking with little fine-tuning. The G group structure and the requirement of proton stability determine the nature of the light composite states accompanying the Higgs and the top quark: a coloured triplet scalar and several vector-like fermions with exotic quantum numbers. We analyse the signatures of these composite partners at hadron colliders: distinctive final states contain multiple top and bottom quarks, either alone or accompanied by a heavy stable charged particle, or by missing transverse energy.Comment: 55 pages, 13 figures, final version to be published in JHE

Fetal growth velocity standards from the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project.

BACKGROUND: Human growth is susceptible to damage from insults, particularly during periods of rapid growth. Identifying those periods and the normative limits that are compatible with adequate growth and development are the first key steps toward preventing impaired growth. OBJECTIVE: This study aimed to construct international fetal growth velocity increment and conditional velocity standards from 14 to 40 weeks' gestation based on the same cohort that contributed to the INTERGROWTH-21st Fetal Growth Standards. STUDY DESIGN: This study was a prospective, longitudinal study of 4321 low-risk pregnancies from 8 geographically diverse populations in the INTERGROWTH-21st Project with rigorous standardization of all study procedures, equipment, and measurements that were performed by trained ultrasonographers. Gestational age was accurately determined clinically and confirmed by ultrasound measurement of crown-rump length at <14 weeks' gestation. Thereafter, the ultrasonographers, who were masked to the values, measured the fetal head circumference, biparietal diameter, occipitofrontal diameter, abdominal circumference, and femur length in triplicate every 5 weeks (within 1 week either side) using identical ultrasound equipment at each site (4-7 scans per pregnancy). Velocity increments across a range of intervals between measures were modeled using fractional polynomial regression. RESULTS: Peak velocity was observed at a similar gestational age: 16 and 17 weeks' gestation for head circumference (12.2 mm/wk), and 16 weeks' gestation for abdominal circumference (11.8 mm/wk) and femur length (3.2 mm/wk). However, velocity growth slowed down rapidly for head circumference, biparietal diameter, occipitofrontal diameter, and femur length, with an almost linear reduction toward term that was more marked for femur length. Conversely, abdominal circumference velocity remained relatively steady throughout pregnancy. The change in velocity with gestational age was more evident for head circumference, biparietal diameter, occipitofrontal diameter, and femur length than for abdominal circumference when the change was expressed as a percentage of fetal size at 40 weeks' gestation. We have also shown how to obtain accurate conditional fetal velocity based on our previous methodological work. CONCLUSION: The fetal skeleton and abdomen have different velocity growth patterns during intrauterine life. Accordingly, we have produced international Fetal Growth Velocity Increment Standards to complement the INTERGROWTH-21st Fetal Growth Standards so as to monitor fetal well-being comprehensively worldwide. Fetal growth velocity curves may be valuable if one wants to study the pathophysiology of fetal growth. We provide an application that can be used easily in clinical practice to evaluate changes in fetal size as conditional velocity for a more refined assessment of fetal growth than is possible at present (https://lxiao5.shinyapps.io/fetal_growth/). The application is freely available with the other INTERGROWTH-21st tools at https://intergrowth21.tghn.org/standards-tools/