Design of conditions for emergence of self-replicators

A self-replicator is usually understood to be an object of definite form that promotes the conversion of materials in its environment into a nearly identical copy of itself. The challenge of engineering novel, micro- or nano-scale self-replicators has attracted keen interest in recent years, both because exponential amplification is an attractive method for generating high yields of specific products, and also because self-reproducing entities have the potential to be optimized or adapted through rounds of iterative selection. Substantial steps forward have been achieved both in the engineering of particular self-replicating molecules, and also in characterizing the physical basis for possible mechanisms of self-replication. At present, however, there is need for a theoretical treatment of what physical conditions are most conducive to the emergence of novel self-replicating structures from a reservoir of building blocks on a desired time-scale. Here we report progress in addressing this need. By analyzing the dynamics of a generic class of heterogeneous particle mixtures whose reaction rates emerge from basic physical interactions, we demonstrate that the spontaneous discovery of self-replication is controlled by relatively generic features of the chemical space, namely: the dispersion in the distribution of reaction timescales and bound-state energies. Based on this analysis, we provide quantitative criteria that may aid experimentalists in designing a system capable of producing self-replicators, and in estimating the likely timescale for exponential growth to start.Comment: Supplementary Information is under the Ancillary Files ---

Information-theoretic bound on the entropy production to maintain a classical nonequilibrium distribution using ancillary control

There are many functional contexts where it is desirable to maintain a mesoscopic system in a nonequilibrium state. However, such control requires an inherent energy dissipation. In this article, we unify and extend a number of works on the minimum energetic cost to maintain a mesoscopic system in a prescribed nonequilibrium distribution using ancillary control. For a variety of control mechanisms, we find that the minimum amount of energy dissipation necessary can be cast as an information-theoretic measure of distinguishability between the target nonequilibrium state and the underlying equilibrium distribution. This work offers quantitative insight into the intuitive idea that more energy is needed to maintain a system farther from equilibrium.Comment: 6 pages, 2 figure

Morphogen Gradient from a Noisy Source

We investigate the effect of time-dependent noise on the shape of a morphogen gradient in a developing embryo. Perturbation theory is used to calculate the deviations from deterministic behavior in a simple reaction-diffusion model of robust gradient formation, and the results are confirmed by numerical simulation. It is shown that such deviations can disrupt robustness for sufficiently high noise levels, and the implications of these findings for more complex models of gradient-shaping pathways are discussed.Comment: Four pages, three figure

Statistical Physics of Self-Replication

Self-replication is a capacity common to every species of living thing, and simple physical intuition dictates that such a process must invariably be fueled by the production of entropy. Here, we undertake to make this intuition rigorous and quantitative by deriving a lower bound for the amount of heat that is produced during a process of self-replication in a system coupled to a thermal bath. We find that the minimum value for the physically allowed rate of heat production is determined by the growth rate, internal entropy, and durability of the replicator, and we discuss the implications of this finding for bacterial cell division, as well as for the pre-biotic emergence of self-replicating nucleic acids.Comment: 4+ pages, 1 figur

Extending electron orbital precession to the molecular case: Can orbital alignment be used to observe wavepacket dynamics?

The complexity of ultrafast molecular photoionization presents an obstacle to the modelling of pump-probe experiments. Here, a simple optimized model of atomic rubidium is combined with a molecular dynamics model to predict quantitatively the results of a pump-probe experiment in which long range rubidium dimers are first excited, then ionized after a variable delay. The method is illustrated by the outline of two proposed feasible experiments and the calculation of their outcomes. Both of these proposals use Feshbach 87Rb2 molecules. We show that long-range molecular pump-probe experiments should observe spin-orbit precession given a suitable pump-pulse, and that the associated high-frequency beat signal in the ionization probability decays after a few tens of picoseconds. If the molecule was to be excited to only a single fine structure state state, then a low-frequency oscillation in the internuclear separation would be detectable through the timedependent ionization cross section, giving a mechanism that would enable observation of coherent vibrational motion in this molecule.Comment: 9 pages, 10 figures, PRA submissio

Oxidation processes in magneto-optic and related materials

The surface oxidation processes of thin films of magneto-optic materials, such as the rare-earth transition metal alloys have been studied, starting in ultrahigh vacuum environments, using surface analysis techniques, as a way of modeling the oxidation processes which occur at the base of a defect in an overcoated material, at the instant of exposure to ambient environments. Materials examined have included FeTbCo alloys, as well as those same materials with low percentages of added elements, such a Ta, and their reactivities to both O2 and H2O compared with materials such as thin Fe films coated with ultrathin adlayers of Ti. The surface oxidation pathways for these materials is reviewed, and XPS data presented which indicates the type of oxides formed, and a critical region of Ta concentration which provides optimum protection

The University of Alabama Libraries and Student Support Services Partnership: Non-Traditional Outreach to Academic Support Programs

Abstract: At the University of Alabama Libraries we have partnered with the Student Support Services TRiO program, a grant-funded program through the U. S. Department of Education that works to increase the retention and graduation rates of first generation college students, students with limited family income, and students with disabilities. We have developed a program that utilizes a combination of classroom instruction in the library and outreach hours at the Student Support Services building, we are able to engage with the students on multiple levels while remaining cognizant of any accommodations they may require. We provide instruction on utilizing the library’s website as well as one-on-one consultations for students who need research support. Although this program is only in its second semester it has proved quite successful and we see great potential for expansion to other non-traditional academic services on campus. Originally presented at the Atlanta Area Bibliographic Instruction Group conference, June 2016.https://ir.una.edu/libfacpresentation/1002/thumbnail.jp

Outreach to Student Support Services at the University of Alabama: Engaging While Including

Outreach programs on university campuses are crucial to reducing anxiety in students from diverse backgrounds who may not have been introduced to an academic library environment, its resources, and its role in their academic success. Traditional liaison programs are geared towards students within their majors; as the campus evolves, so must the role of the liaison. At the University of Alabama Libraries we have partnered with the Student Support Services (SSS) TRiO program, a grant-funded program through the U. S. Department of Education that works to increase the retention and graduation rates of first generation college students, students with limited family income, and students with disabilities. Boasting a 91% average retention rate, the program works with a broad spectrum of students. By the numbers, the students in the program are 65% female, 74% are low income and first generation, and 62% are Black or African American. The presenters, working in conjunction with the Academic Counselors in SSS, have created a comprehensive outreach program through which they are able to engage with the students on multiple levels while remaining cognizant of the pressures and needs of the individual students in the program. In addition to open houses, instruction, and Libguides, the presenters have also secured spaces within the Student Support Services building during high traffic periods for visibility and ease of interaction. Meeting with students in familiar spaces provides them a comfortable way to interact and learn research skills, website navigation, and other services that the library provides. Once the student has established a relationship with the librarian, they are more likely to visit the library and utilize more library services, which contributes to the student’s overall academic success.https://ir.una.edu/libfacpresentation/1004/thumbnail.jp

Partnering with Academic Support Programs to Promote Student Success

Outreach programs on university campuses are crucial to reducing anxiety in students from diverse backgrounds who may not have been introduced to an academic library environment, its resources, and its role in their academic success. Traditional liaison programs are geared towards students within their majors; as the campus evolves, so must the role of the liaison. At the University of Alabama Libraries we have partnered with the Student Support Services (SSS) TRiO program, a grant-funded program through the U. S. Department of Education that works to increase the retention and graduation rates of first generation college students, students with limited family income, and students with disabilities. The presenters, working in conjunction with the Academic Counselors in SSS, have created a comprehensive outreach program through which they are able to engage with the students on multiple levels while remaining cognizant of the pressures and needs of the individual students in the program.https://ir.una.edu/libfacpresentation/1009/thumbnail.jp