Signalling, cell cycle and pluripotency in embryonic stem cells

International audienc

Social Dynamics of Gang Involvement: A Mathematical Approach

Gangs have played a significant role in the social and political history of the United States, and continue to impact the country today, as gang violence and participation rates continue to grow. In this paper, we explore the dynamics of gang involvement between at-risk individuals, gang members, and reformed gang members using an SIR-type model. We investigate the effect that social influence of reformed gang members has on the at-risk population using a general function, which takes into account the cost of gang membership and a threat factor. Our results show that the influence of the reformed population is highly sensitive to initial gang member population size, recidivism, and cost

The Battlefield of Pluripotency

SummaryHow embryonic stem cells maintain the potential to differentiate into multiple cell lineages is still unclear. In this issue of Cell, Niwa et al. (2005) show that a duel between the transcription factors Oct3/4 and Cdx2 can restrict embryonic stem cells to either embryonic or placental fate. The vulnerability of lineage potential to transcriptional perturbation may reflect an essential feature of pluripotency

Sensitivity analysis of the space shuttle to ascent wind profiles

A parametric sensitivity analysis of the space shuttle ascent flight to the wind profile is presented. Engineering systems parameters are obtained by flight simulations using wind profile models and samples of detailed (Jimsphere) wind profile measurements. The wind models used are the synthetic vector wind model, with and without the design gust, and a model of the vector wind change with respect to time. From these comparison analyses an insight is gained on the contribution of winds to ascent subsystems flight parameters

Stream Water Quality to Support HUC 12 Prioritization in the Lake Wister Watershed, Oklahoma: August 2017 through May 2019

Nonpoint source pollution associated with human land use (agriculture and urbanization) is one of the leading causes of impairment to waterways in the United States (EPA 2000). The primary pollutants associated with agricultural and urban land use are sediment and nutrients which enter nearby streams during rain events and are then carried downstream. These sediments and nutrients may result in water quality issues in the downstream water bodies like increased algal growth or decreased water clarity (e.g. Smith et al., 1999). Best management practices (BMPs) are often used to mitigate the effects of nonpoint source pollution in the watershed. Practices such as riparian buffers installed along the edge of field and conservation tillage (e.g., no-till, spring-till, and cover crops) slow overland flow, reducing erosion and nutrient loss from the landscape (Schoumans et al. 2014). Installing BMPs throughout the entire watershed would have the greatest effect at reducing nonpoint source pollution; however, this is not socially or economically feasible. Targeting critical source areas or priority watersheds for BMPs installation, optimizes the benefits while reducing the overall (Sharpley et al. 2000)

Impact of a Student Leadership Experience on the Development of Creativity in Undergraduate Students

The purpose of this study was to examine the impact of a leadership experience on the development of creativity in undergraduate students in order to help student affairs professionals, faculty, and administrators better understand how they can develop creativity in their students. A phenomenological study was conducted on students who held a leadership position as a Resident Assistant or cabinet member of a student organization on the campus of a small institution in the Midwestern United States. The study consisted of an open-ended survey and semistructured interviews. Key findings from this study include insight into various aspects of students’ experiences in leadership including event planning, supervisors, collaboration, impact on communication, looking past failure, incorporation of interests into their roles, redefining creativity through their roles, and the students’ creative self-efficacy. These findings additionally provide support for the idea that a leadership experience is an effective method for teaching creativity to undergraduate students

Watershed Investigative Support to the Poteau Valley Improvement Authority: Stream Water Quality to Support HUC 12 Prioritization in the Lake Wister Watershed, Oklahoma

Nonpoint source pollution associated with human land use (agriculture and urbanization) is one of the leading causes of impairment to waterways in the United States (EPA, 2000). The primary pollutants associated with agricultural and urban land use are sediment and nutrients which enter nearby streams during rain events and are then carried downstream. These sediments and nutrients may result in water quality issues in the downstream water bodies like increased algal growth or decreased water clarity (e.g. Smith et al., 1999)

Design and Fabrication of FDM 3D Printed Strain Sensors

As technology related to virtual reality, prosthetics, and robotics advances there appears a need for better sensor technology to augment these systems. In particular, many of the systems must interphase with the human body or the environment while maintaining large amounts of mobility and flexibility. This creates the demand for flexible electronics in particular flexible strain sensors to monitor movement. The work presented here explores the feasibility of commercially available elastic filament and desktop Fused Deposition Modeling (FDM) 3D printing as a simple and cost-effective route to develop flexible single-axis strain sensors. 3D printing allows for the rapid production and prototyping of designs at relatively low cost. 3D printing is used to fabricate the strain sensor substrate. The sensitivity of the strain sensor is then observed by calculating the gauge factor from experimental data. From this, the viability of FDM 3D printing and commercially available filament for the creation of strain sensors can be determined. Three sensors measuring approximately 2100 μm by 199 μm are fabricated. Results demonstrate gauge factors from 1 to 2 at 38.6% strain with high linearity and little hysteresis. Additionally, two smaller strain sensors, measuring approximately 696 μm by 203 μm, are fabricated with gauge factors of nearly 0.9 at 13% strain. Results show that stress accumulation and permanent deformation play an essential role in determining the functionality of these 3D printed sensors. The results from this work demonstrate the potential of additive manufacturing to produce complex designs and sensor platforms for a wide range of applications

Agreement Level of Running Temporal Measurements, Kinetics, and Force-Time Curves Calculated from Inertial Measurement Units

Inertial measurement units (IMUs) and wearable sensors have enabled athlete monitoring and research to become more ecologically valid due to their small size and low cost. IMUs and accelerometers that are placed on the body close to the point of impact and that record at sufficiently high frequencies have demonstrated the highest validity when measuring temporal gait event moments such as ground contact time (GCT) and flight time (FT) as well as peak forces (PF) during upright running. While the use of IMUs has increased in the sport performance and athlete monitoring realm, the potential of the technology’s ability to estimate running force-time curves utilizing the two-mass model (TMM) remains unexplored. The purpose of this study was two-fold. First, was to determine the validity of measuring temporal gait events and peak forces utilizing a commercially available shank-mounted inertial measurement unit. Second, was to determine the validity of force-time curves generated from the TMM utilizing data from shank-mounted inertial measurement units. Ten subjects voluntarily completed submaximal treadmill tests equipped with a force plate while wearing shank-mounted IMUs on each leg. Using the raw data from the IMUs, GCT, FT, total step time (ST), PF, and two-mass model-based force-time (F-t) curves were generated for 25 steps at 8 different speeds. Paired sample T-tests were performed on the gait events and peak force between the IMU and treadmill with both individual step comparison and averages per each speed. 95% confidence intervals were calculated for each timepoint of the force time curves. No statistically significant differences (p \u3e 0.05) and nearly perfect relationships were observed for the step averages for each speed with FT, ST, and PF. Confidence intervals of the corrected mean difference suggest that F-t curves calculated from the TMM may not be valid when assessing the running population as a whole. When performing a sub-group analysis of skilled runners and recreational runners, F-t curves derived from shank-mounted IMUs may be more valid in skilled runners than recreational runners. In skilled runners, the 95% CI for the mean difference contained zero within the first 60% of the GCT duration, whereas the 95% CI recreational runners contained a zero-value in a smaller percentage of the GCT located only in the middle of the GCT at the curve peak height. The results of this study suggest that interchangeability between shank-mounted IMUs and force plates may be very limited when estimating temporal gait events and kinetics. While agreement was low between F-t curves after the peak in skilled runners, use of shank-mounted IMUs to estimate F-t curves may have several benefits still in skilled runners when assessing peak forces and force development from initial contact until peak force