Control of stochastic and induced switching in biophysical networks

Noise caused by fluctuations at the molecular level is a fundamental part of intracellular processes. While the response of biological systems to noise has been studied extensively, there has been limited understanding of how to exploit it to induce a desired cell state. Here we present a scalable, quantitative method based on the Freidlin-Wentzell action to predict and control noise-induced switching between different states in genetic networks that, conveniently, can also control transitions between stable states in the absence of noise. We apply this methodology to models of cell differentiation and show how predicted manipulations of tunable factors can induce lineage changes, and further utilize it to identify new candidate strategies for cancer therapy in a cell death pathway model. This framework offers a systems approach to identifying the key factors for rationally manipulating biophysical dynamics, and should also find use in controlling other classes of noisy complex networks.Comment: A ready-to-use code package implementing the method described here is available from the authors upon reques

Differences in Peer Bullying Victimization by Race and Gender: The Impact of Proficiency, Enjoyment, and Confidence in Math and Science

Despite a significant amount of study and intervention, racial minority students continue to perform at a lower level than their White peers, while female students lag behind their male peers, in terms of math and science achievement. The consistency and resiliency of this achievement gap suggests that these patterns of performance may have become societal expectations. As minority and female students attempt to increase their level of math and science academic performance, and, therefore, violate societal expectations, they may experience a higher risk of another pervasive problem: peer bullying victimization. Previous research has demonstrated that academic success, stereotype violation, race, and gender have all been associated with the experience of bullying. Using the 2011 8th grade, United States sample of the Trends in International Math and Science Study (TIMSS 2011), the current study attempts to determine if racial minority students report higher rates of bullying victimization than White students, and if female students report higher rates of bullying victimization than male students, after controlling for the effects of math and science ability, enjoyment, and confidence. Results indicate that female students do report significantly higher rates of victimization than their male peers, while Hispanic students report significantly higher rates of victimization than their White and Multi-Racial peers. However, while significant differences were shown to exist, those differences represented trivial effect sizes and, therefore, appear to have little noticeable impact on students’ bullying experiences. Results related to supplementary analyses, as well as limitations and implications for future research are also discussed

Poultry litter ash as a phosphorus source for greenhouse crop production

Phosphorus (P) is an essential nutrient for all life forms, including plants, but is a limited agricultural resource whose future availability is in question. Therefore, identification of alternative forms of P fertilizers is important. Poultry litter ash (PLA), a byproduct of bioenergy production, contains high concentrations of P comparable to conventional fertilizers. Forms of P contained in PLA have been characterized as having low water solubility. Nutrient losses during containerized plant production are high due to excessive inputs of water and nutrients and low nutrient sorption capacities of common horticultural substrate components. Environmental concerns over reduced water quality intensify this problem. Use of low soluble P sources has been recommended as a potential means of reducing P losses. Experiments were conducted to determine effects of PLA application on growth, quality, and nutrient uptake of two greenhouse crops (Verbena canadensis Britton ‘Homestead Purple’ and Lantana camara L.‘New Gold’), substrate chemical properties, and P losses during greenhouse crop production. In the first experiment, substrate leachate-pH increased 25% when PLA was applied instead of superphosphate (SP). Foliar P concentrations of verbena and lantana also increased 27 and 62%, respectively. Application of PLA did not reduce biomass of verbena or lantana. In a subsequent experiment, leachate-dissolved reactive phosphorus (DRP) and effluent-total phosphorus (TP) concentrations were reduced \u3e92% and 69%, respectively, through PLA application, however, plant growth and landscape establishment was not deleteriously affected. Water solubility of PLA-P decreased markedly as combustion temperature increased. Finally, in a third experiment, concentrations of DRP were reduced 24% through reduction of PLA rate, but were reduced 134% when PLA was topdressed instead of incorporated. Plant quality was improved with PLA incorporation. These results indicate that, while P loss reduction can be achieved through PLA application, lower substrate P concentrations do not necessarily reduce plant growth or quality

GENERAL FLIPS AND THE CD-INDEX

We generalize bistellar operations (often called flips) on simplicial manifolds to a notion of general flips on PL-spheres. We provide methods for computing the cd-index of these general flips, which is the change in the cd-index of any sphere to which the flip is applied. We provide formulas and relations among flips in certain classes, paying special attention to the classic case of bistellar flips. We also consider questions of flip-connecticity , that is, we show that any two polytopes in certain classes can be connected via a sequence of flips in an appropriate class

Model-Independent Description and Large Hadron Collider Implications of Suppressed Two-Photon Decay of a Light Higgs Boson

For a Standard Model Higgs boson with mass between 115 GeV and 150 GeV, the two-photon decay mode is important for discovery at the Large Hadron Collider (LHC). We describe the interactions of a light Higgs boson in a more model-independent fashion, and consider the parameter space where there is no two-photon decay mode. We argue from generalities that analysis of the $t\bar t h$ discovery mode outside its normally thought of range of applicability is especially needed under these circumstances. We demonstrate the general conclusion with a specific example of parameters of a type I two-Higgs doublet theory, motivated by ideas in strongly coupled model building. We then specify a complete set of branching fractions and discuss the implications for the LHC.Comment: 4 pages, 4 figure

Containment Forces in Low Energy States of Plasmoids

The application of Hamilton\u27s principle to the problem of the determination of the structure of low free energy state plasmoids is discussed. It is shown that Clebsch representations of the vector fields and representations involving side conditions on the functional result in the same sets of Euler–Lagrange equations. The relationship of these representations to the problem of containment forces in vortex structures (plasmoids) is considered. It is demonstrated that the lowest free energy state of an incompressible plasma is always Lorentz force and Magnus force free. For a compressible plasma obeying the adiabatic gas laws, the Magnus force is finite. Introduction of conservation of angular momentum as an additional side condition also results in finite containment force

Fault Slip and Exhumation History of the Willard Thrust Sheet, Sevier Fold‐Thrust Belt, Utah: Relations to Wedge Propagation, Hinterland Uplift, and Foreland Basin Sedimentation

Zircon (U‐Th)/He (ZHe) and zircon fission track thermochronometric data for 47 samples spanning the areally extensive Willard thrust sheet within the western part of the Sevier fold‐thrust belt record enhanced cooling and exhumation during major thrust slip spanning approximately 125–90 Ma. ZHe and zircon fission track age‐paleodepth patterns along structural transects and age‐distance relations along stratigraphic‐parallel traverses, combined with thermo‐kinematic modeling, constrain the fault slip history, with estimated slip rates of ~1 km/Myr from 125 to 105 Ma, increasing to ~3 km/Myr from 105 to 92 Ma, and then decreasing as major slip was transferred onto eastern thrusts. Exhumation was concentrated during motion up thrust ramps with estimated erosion rates of ~0.1 to 0.3 km/Myr. Local cooling ages of approximately 160–150 Ma may record a period of regional erosion, or alternatively an early phase of limited... (see full abstract in article)