The mm-colored composition poset

We generalize Bj\"{o}rner and Stanley's poset of compositions to $m$-colored compositions. Their work draws many analogies between their (1-colored) composition poset and Young's lattice of partitions, including links to (quasi-)symmetric functions and representation theory. Here we show that many of these analogies hold for any number of colors. While many of the proofs for Bj\"{o}rner and Stanley's poset were simplified by showing isomorphism with the subword order, we remark that with 2 or more colors, our posets are not isomorphic to a subword order.Comment: 12 pages, 1 figur

THE EFFECTS OF FATIGUE ON RACE WALKING TECHNIQUE

The purpose of this study was to measure the effects of fatigue on gait parameters during race walking. Research has shown that fatigued athletes require gait alterations in order to maintain speed. Eighteen competitive race walkers walked either 5 km or 10 km at a pace equivalent to 105% of their season’s best time. Junior athletes walked 5 km, while senior athletes (mostly 20 km walkers) walked 10 km. Kinetic data were collected using a Gaitway treadmill (1000 Hz). Data were collected at three points during the 5 km walks and at four points during the 10 km walks. Repeated measures ANOVA showed that there were significant differences in impulse and contact time parameters (p < .01). The kinetic and temporal changes occurred as early as 1 km. Athletes are recommended to race at a constant pace to reduce the effects of fatigue

MUSCLE ACTIVITY OF THE STANCE KNEE IN ELITE RACE WALKERS

The purpose of this study was to compare knee muscle activity in race walkers with different knee extension patterns. Three international athletes walked over two force plates recording at 1000 Hz. Video data were simultaneously recorded at 100 Hz; the digitised data were combined with the force data to calculate net muscle moments and joint powers. EMG testing was carried out on three muscles which cross the knee. The two walkers with legal techniques had similar moment and power patterns, whereas the non-legal walker experienced a longer period of eccentric flexor moment at the beginning of stance, which may have affected his ability to extend his knee correctly. After this, all three athletes experienced a period of isometric contraction at the knee. Achieving correct technique requires both strength endurance exercises and mobility development

Monomial Nonnegativity and the Bruhat Order

We show that five nonnegativity properties of polynomials coincide when restricted to polynomials of the form x1, pi(1) ... xn,pi(n) - x1, sigma(1) ... xn, sigma(n), where $\pi and sigma are permutations in Sn. In particular, we show that each of these properties may be used to characterize the Bruhat order on Sn

THE CONTRIBUTION OF THE FLIGHT PHASE IN ELITE RACE WALKING

Although race walkers are not permitted a visible flight phase, previous research has found that most competitors do experience very brief losses of contact. The purpose of this study was to assess the role of the flight phase in elite race walking. Seventeen international athletes race walked over two force plates recording at 1000 Hz. Video data were simultaneously recorded at 100 Hz and used to calculate kinematic variables such as step length. The mean flight time was 0.030 s (± .011) while the mean distance travelled during this phase was 0.12 m (± .05). It was calculated that without flight times, athletes would have slower mean velocities, particularly if mean cadence remained the same. However, the contribution of flight phases in race walking does not just allow for greater step lengths and faster speeds, but also more time for lower limb repositioning

GROUND REACTION FORCES OF NATIONAL LEVEL RACE WALKERS

The purpose of this study was to measure and analyse ground reaction force variables during race walking. Fourteen national level race walkers, eight men and six women, walked at race pace over two force plates recording at 1000 Hz. Men and women had comparable force trace patterns except for the magnitude of the weight-loading peak force. There were similarities with normal ground reaction force patterns, although the drop in vertical force at midstance and subsequent rise in vertical push-off force typical of normal walking were not observed. This was considered to be due to the straightened knee rule of race walking and the need to reduce vertical displacment and flight time. The medial forces were greater than those in normal walking and this may be related to the frontal plane motions of the pelvis

Re-engineering Nascom's network management architecture

The development of Nascom systems for ground communications began in 1958 with Project Vanguard. The low-speed systems (rates less than 9.6 Kbs) were developed following existing standards; but, there were no comparable standards for high-speed systems. As a result, these systems were developed using custom protocols and custom hardware. Technology has made enormous strides since the ground support systems were implemented. Standards for computer equipment, software, and high-speed communications exist and the performance of current workstations exceeds that of the mainframes used in the development of the ground systems. Nascom is in the process of upgrading its ground support systems and providing additional services. The Message Switching System (MSS), Communications Address Processor (CAP), and Multiplexer/Demultiplexer (MDM) Automated Control System (MACS) are all examples of Nascom systems developed using standards such as, X-windows, Motif, and Simple Network Management Protocol (SNMP). Also, the Earth Observing System (EOS) Communications (Ecom) project is stressing standards as an integral part of its network. The move towards standards has produced a reduction in development, maintenance, and interoperability costs, while providing operational quality improvement. The Facility and Resource Manager (FARM) project has been established to integrate the Nascom networks and systems into a common network management architecture. The maximization of standards and implementation of computer automation in the architecture will lead to continued cost reductions and increased operational efficiency. The first step has been to derive overall Nascom requirements and identify the functionality common to all the current management systems. The identification of these common functions will enable the reuse of processes in the management architecture and promote increased use of automation throughout the Nascom network. The MSS, CAP, MACS, and Ecom projects have indicated the potential value of commercial-off-the-shelf (COTS) and standards through reduced cost and high quality. The FARM will allow the application of the lessons learned from these projects to all future Nascom systems

Recent Transits of the Super-Earth Exoplanet GJ 1214b

We report recent ground-based photometry of the transiting super-Earth exoplanet GJ1214b at several wavelengths, including the infrared near 1.25 microns (J-band). We observed a J-band transit with the FLAMINGOS infrared imager and the 2.1-meter telescope on Kitt Peak, and we observed several optical transits using a 0.5-meter telescope on Kitt Peak and the 0.36-meter Universidad de Monterrey Observatory telescope. Our high-precision J-band observations exploit the brightness of the M-dwarf host star at this infrared wavelength as compared to the optical, as well as being significantly less affected by stellar activity and limb darkening. We fit the J-band transit to obtain an independent determination of the planetary and stellar radii. Our radius for the planet (2.61^+0.30_-0.11 Earth radii) is in excellent agreement with the discovery value reported by Charbonneau et al. based on optical data. We demonstrate that the planetary radius is insensitive to degeneracies in the fitting process. We use all of our observations to improve the transit ephemeris, finding P=1.5804043 +/- 0.0000005 days, and T0=2454964.94390 +/- 0.00006 BJD.Comment: Accepted for ApJ Letters, 7 pages, 3 Figures, 2 Table

Maternal obesity has little effect on the immediate offspring but impacts on the next generation

Maternal obesity during pregnancy has been linked to an increased risk of obesity and cardiometabolic disease in the offspring, a phenomenon attributed to developmental programming. Programming effects may be transmissible across generations through both maternal and paternal inheritance, although the mechanisms remain unclear. Using a mouse model, we explored the effects of moderate maternal diet-induced obesity (DIO) on weight gain and glucose-insulin homeostasis in first-generation (F1) and second-generation offspring. DIO was associated with insulin resistance, hyperglycemia and dyslipidemia before pregnancy. Birth weight was reduced in female offspring of DIO mothers (by 6%, P = .039), and DIO offspring were heavier than controls at weaning (males by 47%, females by 27%), however there were no differences in glucose tolerance, plasma lipids, or hepatic gene expression at 6 months. Despite the relative lack of effects in the F1, we found clear fetal growth restriction and persistent metabolic changes in otherwise unmanipulated second-generation offspring with effects on birth weight, insulin levels, and hepatic gene expression that were transmitted through both maternal and paternal lines. This suggests that the consequences of the current dietary obesity epidemic may also have an impact on the descendants of obese individuals, even when the phenotype of the F1 appears largely unaffected