Nonlinear Machine Learning and Design of Reconfigurable Digital Colloids

Digital colloids, a cluster of freely rotating “halo particles tethered to the surface of a central particle, were recently proposed as ultra-high density memory elements for information storage. Rational design of these digital colloids for memory storage applications requires a quantitative understanding of the thermodynamic and kinetic stability of the configurational states within which information is stored. We apply nonlinear machine learning to Brownian dynamics simulations of these digital colloids to extract the low-dimensional intrinsic manifold governing digital colloid morphology, thermodynamics, and kinetics. By modulating the relative size ratio between halo particles and central particles, we investigate the size-dependent configurational stability and transition kinetics for the 2-state tetrahedral (N=4) and 30-state octahedral (N=6) digital colloids. We demonstrate the use of this framework to guide the rational design of a memory storage element to hold a block of text that trades off the competing design criteria of memory addressability and volatility

The Role of Conflict and Conflict Management/Resolution in Face to Face and Remote Collaboration: A Content Analysis of a Controlled Experiment

Collaborating effectively is essential in getting work done. Regardless of physical location, being able to effectively communicate ideas and tasks to one another is essential in completing successful work. The objective of the study is to observe conflict and conflict management techniques and see how they affect a group's ability to produce good work. The study is a content analysis of video and audio produced by a separate study conducted by researchers at the University of North Carolina at Chapel Hill. The UNC study focused on the relationship between the lab environment (face to face vs. remote) of a scientific experiment and the quality of the lab reports produced. The tapes from the UNC study were coded according to a coding system devised to capture types of conflict and types of conflict management/resolution techniques. Descriptive statistics taken from the coding were compared to lab grades to infer possible affects that conflict and conflict management/resolution may have on the final lab grades

Evidence for Ubiquitous Collimated Galactic-Scale Outflows along the Star-Forming Sequence at z~0.5

We present an analysis of the MgII 2796, 2803 and FeII 2586, 2600 absorption line profiles in individual spectra of 105 galaxies at 0.3<z<1.4. The galaxies, drawn from redshift surveys of the GOODS fields and the Extended Groth Strip, fully sample the range in star formation rates (SFRs) occupied by the star-forming sequence with stellar masses log M_*/M_sun > 9.5 at 0.3<z<0.7. Using the Doppler shifts of the MgII and FeII absorption lines as tracers of cool gas kinematics, we detect large-scale winds in 66+/-5% of the galaxies. HST/ACS imaging and our spectral analysis indicate that the outflow detection rate depends primarily on galaxy orientation: winds are detected in ~89% of galaxies having inclinations (i) <30 degrees (face-on), while the wind detection rate is only ~45% in objects having i>50 degrees (edge-on). Combined with the comparatively weak dependence of the wind detection rate on intrinsic galaxy properties, this suggests that biconical outflows are ubiquitous in normal, star-forming galaxies at z~0.5. We find that the wind velocity is correlated with host galaxy M_* at 3.4-sigma significance, while the equivalent width of the flow is correlated with host galaxy SFR at 3.5-sigma significance, suggesting that hosts with higher SFR may launch more material into outflows and/or generate a larger velocity spread for the absorbing clouds. Assuming that the gas is launched into dark matter halos with simple, isothermal density profiles, the wind velocities measured for the bulk of the cool material (~200-400 km/s) are sufficient to enable escape from the halo potentials only for the lowest-M_* systems in the sample. However, the outflows typically carry sufficient energy to reach distances of >50 kpc, and may therefore be a viable source of cool material for the massive circumgalactic medium observed around bright galaxies at z~0. [abridged]Comment: Submitted to ApJ. 61 pages, 25 figures, 4 tables, 4 appendices. Uses emulateapj forma

Evolutionary predictions for a parasite metapopulation: Modelling salmon louse resistance to pest controls in aquaculture

publishedVersio

Hypoxia as a target for drug combination therapy of liver cancer

Hepatocellular carcinoma (HCC) is the third most frequentcause of cancer deaths worldwide. The standard of care for intermediate HCC is transarterial chemoembolization, which combines tumour embolization with locoregional delivery of the chemotherapeutic doxorubicin. Embolization therapies induce hypoxia, leading to the escape and proliferation of hypoxia-adapted cancer cells. The transcription factor that orchestrates responses to hypoxia is hypoxia-inducible factor 1 (HIF-1). The aim of this work is to show that targeting HIF-1 with combined drug therapy presents an opportunity for improving outcomes for HCC treatment. HepG2 cells were cultured under normoxic and hypoxic conditions exposed to doxorubicin, rapamycin and combinations thereof, and analyzed for viability and the expression of hypoxia-induced HIF-1α in response to these treatments. A pilot study was carried out to evaluate the antitumour effects of these drug combinations delivered from drug-eluting beads in vivo using an ectopic xenograft murine model of HCC. A therapeutic doxorubicin concentration that inhibits the viability of normoxic and hypoxic HepG2 cells and above which hypoxic cells are chemoresistant was identified, together with the lowest effective dose of rapamycin against normoxic and hypoxicHepG2 cells. It was shown that combinations of rapamycinand doxorubicin are more effective than doxorubicin alone. Western Blotting indicated that both doxorubicin and rapamycin inhibit hypoxia-induced accumulation of HIF-1α. Combination treatments were more effective in vivo than either treatment alone. mTOR inhibition can improve outcomes of doxorubicin treatment in HCC Anti-Cancer

A metapopulation model reveals connectivity-driven hotspots in treatment resistance evolution in a marine parasite

In salmon aquaculture, the sustainable management of salmon lice (Lepeophtheirus salmonis) is limited by the adaptive capacity of the parasite. This is evident in the repeated evolution of pesticide resistance in the salmon louse population. To better prepare for resistance, we constructed a numerical metapopulation model that predicts the evolutionary dynamics of lice across an interconnected farm network. This model integrates within-farm population dynamics and between-farm louse dispersal, the latter using outputs from a state-of-the-art particle-tracking model. Distinct from previous metapopulation models, it also simulates spatial and temporal genetic variation arising from selection. The model was parameterized to simulate the evolution of resistance to the pesticide azamethiphos on farms in southern Norway. It successfully reproduced the rapid (within 10 years) evolution of azamethiphos resistance following extensive delousing treatments. It also identified strong spatial patterns in resistance, with regions of high farm connectivity being potential hotspots of louse adaptation. Rates of infestation and evolution were significantly reduced when highly connected farms were excluded from the simulation, compared to when low-connectivity or random sites were excluded. This model can be a valuable tool for coordinating pest management at a regional scale, in a way that slows or prevents the spread of resistance.A metapopulation model reveals connectivity-driven hotspots in treatment resistance evolution in a marine parasitepublishedVersio

Effective mass and quantum lifetime in a Si/Si0.87Ge0.13/Si two-dimensional hole gas

Measurements of Shubnikov de Haas oscillations in the temperature range 0.3–2 K have been used to determine an effective mass of 0.23 m0 in a Si/Si0.87Ge0.13/Si two-dimensional hole gas. This value is in agreement with theoretical predictions and with that obtained from cyclotron resonance measurements. The ratio of the transport time to the quantum lifetime is found to be 0.8. It is concluded that the 4 K hole mobility of 11 000 cm2 V−1 s−1 at a carrier sheet density of 2.2×1011 cm−2 is limited by interface roughness and short-range interface charge scattering