The Muscle-Mechanical Compromise Framework: Implications for the Scaling of Gait and Posture

Many aspects of animal and human gait and posture cannot be predicted from purely mechanical work minimization or entirely based on optimizing muscle efficiency. Here, the Muscle-Mechanical Compromise Framework is introduced as a conceptual paradigm for considering the interactions and compromises between these two objectives. Current assumptions in implementing the Framework are presented. Implications of the compromise are discussed and related to the scaling of running mechanics and animal posture

Improving the Performance of the Education Sector: The Valuable, Challenging, and Limited Role of Random Assignment Evaluations

In an attempt to improve the quality of educational research, the U.S. Department of Education%u2019s Institute of Education Sciences has provided funding for 65 randomized controlled trials of educational interventions. We argue that this research methodology is more effective in providing guidance to extremely troubled schools about how to make some progress than guidance to schools trying to move from making some progress to becoming high performance organizations. We also argue that the conventional view of medical research -- discoveries made in specialized laboratories that are then tested using randomized control trials -- is an inaccurate description of the sources of advances in medical practice. Moreover, this conventional view of the sources of advances in medical practice leads to incorrect inferences about how to improve educational research. We illustrate this argument using evidence from the history of medical research on the treatment of cystic fibrosis.

SU(3)/SU(2): the simplest Wess-Zumino-Witten term

The observation that SU(3)/SU(2) ~ S^5 implies the existence of a particularly simple quantized topological action, or Wess-Zumino-Witten (WZW) term. This action plays an important role in anomaly cancellation in extensions of the Standard Model electroweak sector. A closed form is presented for the action coupled to arbitrary gauge fields. The action is shown to be equivalent to a limit of the WZW term for SU(3) x SU(3) / SU(3). By reduction of SU(3) x U(1) / SU(2) x U(1) to SU(2) x U(1) / U(1), the construction gives a topological derivation of the WZW term for the Standard Model Higgs field.Comment: 11 pages, 1 figure; references adde

Full Open Population Capture-Recapture Models with Individual Covariates

Traditional analyses of capture-recapture data are based on likelihood functions that explicitly integrate out all missing data. We use a complete data likelihood (CDL) to show how a wide range of capture-recapture models can be easily fitted using readily available software JAGS/BUGS even when there are individual-specific time-varying covariates. The models we describe extend those that condition on first capture to include abundance parameters, or parameters related to abundance, such as population size, birth rates or lifetime. The use of a CDL means that any missing data, including uncertain individual covariates, can be included in models without the need for customized likelihood functions. This approach also facilitates modeling processes of demographic interest rather than the complexities caused by non-ignorable missing data. We illustrate using two examples, (i) open population modeling in the presence of a censored time-varying individual covariate in a full robust-design, and (ii) full open population multi-state modeling in the presence of a partially observed categorical variable

Ionization, Kinematics, and Extent of the Diffuse Ionized Gas Halo of NGC 5775

We present key results from deep spectra of the Diffuse Ionized Gas (DIG) halo of the edge-on galaxy NGC 5775. [NII]6583 has been detected up to about z=13 kpc above the plane in one of two vertically oriented long slits -- making this the spiral galaxy with the greatest spectroscopically detected halo extent in emission. Key diagnostic line ratios have been measured up to about z=8 kpc, allowing the source of ionization and physical state to be probed. Ionization by a dilute radiation field from massive stars in the disk can explain some of the line ratio behavior, but departures from this picture are clearly indicated, most strongly by the rise of [OIII]/Halpha with z. Velocities of the gas in both slits approach the systemic velocity of the galaxy at several kpc above the plane. We interpret this trend as a decrease in rotation velocity with z, with essentially no rotation at heights of several kpc. Such a trend was observed in the edge-on galaxy NGC 891, but here much more dramatically. This falloff is presumably due to the gravitational potential changing with z, but will also depend on the hydrodynamic nature of the disk-halo cycling of gas and projection effects. More detailed modeling of the ionization and kinematics of this and other edge-ons will be presented in future papers.Comment: figures 1, 2a-d and 3 included. ApJ Letters, in pres