Approximate Self-Assembly of the Sierpinski Triangle

The Tile Assembly Model is a Turing universal model that Winfree introduced in order to study the nanoscale self-assembly of complex (typically aperiodic) DNA crystals. Winfree exhibited a self-assembly that tiles the first quadrant of the Cartesian plane with specially labeled tiles appearing at exactly the positions of points in the Sierpinski triangle. More recently, Lathrop, Lutz, and Summers proved that the Sierpinski triangle cannot self-assemble in the "strict" sense in which tiles are not allowed to appear at positions outside the target structure. Here we investigate the strict self-assembly of sets that approximate the Sierpinski triangle. We show that every set that does strictly self-assemble disagrees with the Sierpinski triangle on a set with fractal dimension at least that of the Sierpinski triangle (roughly 1.585), and that no subset of the Sierpinski triangle with fractal dimension greater than 1 strictly self-assembles. We show that our bounds are tight, even when restricted to supersets of the Sierpinski triangle, by presenting a strict self-assembly that adds communication fibers to the fractal structure without disturbing it. To verify this strict self-assembly we develop a generalization of the local determinism method of Soloveichik and Winfree

Shuffle Invariance of the Super-RSK Algorithm

As in the $(k,l)$-RSK (Robinson-Schensted-Knuth) of [1], other super-RSK algorithms can be applied to sequences of variables from the set $\{t_1,...,t_k,u_1,...,u_l\}$, where $t_1<...<t_k$, and $u_1<...<u_l$. While the $(k,l)$-RSK of [1] is the case where $t_i<u_j$ for all $i$ and $j$, these other super-RSK's correspond to all the (\big{(}{{k+l}\atop{k}}\big{)} shuffles of the $t$'s and $u$'s satisfying the above restrictions that $t_1<...<t_k$ and $u_1<...<u_l$. We show that the shape of the tableaux produced by any such super-RSK is independent of the particular shuffle of the $t$'s and $u$'s.Comment: 22 page

Scaled tree fractals do not strictly self-assemble

In this paper, we show that any scaled-up version of any discrete self-similar {\it tree} fractal does not strictly self-assemble, at any temperature, in Winfree's abstract Tile Assembly Model.Comment: 13 pages, 3 figures, Appeared in the Proceedings of UCNC-2014, pp 27-39; Unconventional Computation and Natural Computation - 13th International Conference, UCNC 2014, London, ON, Canada, July 14-18, 2014, Springer Lecture Notes in Computer Science ISBN 978-3-319-08122-

Computational Extensive-Form Games

We define solution concepts appropriate for computationally bounded players playing a fixed finite game. To do so, we need to define what it means for a \emph{computational game}, which is a sequence of games that get larger in some appropriate sense, to represent a single finite underlying extensive-form game. Roughly speaking, we require all the games in the sequence to have essentially the same structure as the underlying game, except that two histories that are indistinguishable (i.e., in the same information set) in the underlying game may correspond to histories that are only computationally indistinguishable in the computational game. We define a computational version of both Nash equilibrium and sequential equilibrium for computational games, and show that every Nash (resp., sequential) equilibrium in the underlying game corresponds to a computational Nash (resp., sequential) equilibrium in the computational game. One advantage of our approach is that if a cryptographic protocol represents an abstract game, then we can analyze its strategic behavior in the abstract game, and thus separate the cryptographic analysis of the protocol from the strategic analysis

Results of post-test psychological examinations of the crewmen from the 90-day manned test of an advanced regenerative life support system

The following material presents the results of two temporally remote administrations of an identical projective personality assessment device (Rorschach Inkblot) using crew members aboard the 90-day test. The first administration took place during preselection crew psychodiagnostic testing in the period extending from mid-December 1969 through mid-January 1970. Second administration took place in late May and early June, 1971, approximately one year after termination of the test. During the 90-day program duration, the subjects participated in the crew training program, were selected and served as onboard crew during the 90-day test. The testing was undertaken in order to determine the character and extent of change (if any) in basic personality dynamics accompanying or caused by participation in the 90-day test program. Results indicate that significant personality changes occurred in three of the four onboard crew members. A detailed discussion of the results is provided. Objective scores which served as the basis for the discussion are presented in the Appendix

Nanoscale Structure and Elasticity of Pillared DNA Nanotubes

We present an atomistic model of pillared DNA nanotubes (DNTs) and their elastic properties which will facilitate further studies of these nanotubes in several important nanotechnological and biological applications. In particular, we introduce a computational design to create an atomistic model of a 6-helix DNT (6HB) along with its two variants, 6HB flanked symmetrically by two double helical DNA pillars (6HB+2) and 6HB flanked symmetrically by three double helical DNA pillars (6HB+3). Analysis of 200 ns all-atom simulation trajectories in the presence of explicit water and ions shows that these structures are stable and well behaved in all three geometries. Hydrogen bonding is well maintained for all variants of 6HB DNTs. We calculate the persistence length of these nanotubes from their equilibrium bend angle distributions. The values of persistence length are ~10 {\mu}m, which is 2 orders of magnitude larger than that of dsDNA. We also find a gradual increase of persistence length with an increasing number of pillars, in quantitative agreement with previous experimental findings. To have a quantitative understanding of the stretch modulus of these tubes we carried out nonequilibrium Steered Molecular Dynamics (SMD). The linear part of the force extension plot gives stretch modulus in the range of 6500 pN for 6HB without pillars which increases to 11,000 pN for tubes with three pillars. The values of the stretch modulus calculated from contour length distributions obtained from equilibrium MD simulations are similar to those obtained from nonequilibrium SMD simulations. The addition of pillars makes these DNTs very rigid.Comment: Published in ACS Nan

Haigus, mis põhjustas uue meditsiinieriala väljakujunemise

Poliomüeliit on viirushaigus, mis võib põhjustada ka jäsemete lõtvu halvatusi, bulbaarparalüüsi ja hingamispuudulikkust. 19. sajandi 80. aastatel ja 20. sajandi esimesel poolel puhkesid poliomüeliidiepideemiad Euroopas ja USAs. Hingamispuudulikkuse raviks konstrueeriti 1927. aastal esimene respiraator – nn raudne kops, mis võimaldas pikaajaliselt ravida hingamispuudulikkusega haigeid. Bulbaarparalüüsi korral hakati laialdaselt kasutama trahheostoomiat. Oluliselt paranesid hingamispuudulikkusega haigete ravi võimalused vahelduva positiivrõhuga hingamisaparaatide kasutuselevõtuga intratrahheaalseks ventilatsiooniks 1948. aastal ja mahuprintsiibil töötava Engströmi respiraatori rakendamisega. 1953. aastal avati Kopenhaagenis maailma esimene intensiivraviosakond. Massilise vaktsineerimise ja poliomüeliidi likvideerimise järel hakati saadud kogemusi rakendama kõikide kriitilises seisundis haigete ravis. Eesti Arst 2009; 88(5):376−38

2012 MLA Small Business, Big Returns

As librarians, more often than not, we are thrust into situations where we know little, and are expected to come back with the perfect catch of the day. Business research waters are murky, but take heart; you are not alone! Come learn from some of Michigan's most successful academic and public business librarians about how they serve the public. This presentation was from the Kresge Business Administration Library (Ross School of Business at the University of Michigan) perspective.http://deepblue.lib.umich.edu/bitstream/2027.42/90943/1/Seeman_BusinessLibrarians_ServingPublicatLarge_2012.ppthttp://deepblue.lib.umich.edu/bitstream/2027.42/90943/2/Seeman_BusinessLibrarians_ServingPublicatLarge_2012.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/90943/3/Additional Comments_MLA2012_Small_Business_Big_Returns.pd

Changing Glasses: Does Our World Look Different as a Vendor or a Librarian?

Librarians and the vendors work very closely together to ensure that information flows between the publishers and the users. However, the relationship can be adversarial at times as both might feel that the other party does not understand their needs. A number of people have had the opportunity to work for both vendors and libraries, revealing a great deal about how these different cultures operate and the impact on this important relationship. We can draw distinct lessons from the different jobs we have had over the years as each job and position provides a unique set of expectations and perspectives that should make a singular imprint on our occupational psyche. From each job, great or small, we can cull a lesson that will help us develop our work ethos. Through our diversity of work experience, we gain a better understanding of the work life and the different expectations and demands that are placed on people within organizations and companies.http://deepblue.lib.umich.edu/bitstream/2027.42/90960/1/Seeman_Changing Glasses_ATG_Final121311.dochttp://deepblue.lib.umich.edu/bitstream/2027.42/90960/2/ATG_corey_seeman.pd