Doubles and Negatives are Positive (in Self-Assembly)

In the abstract Tile Assembly Model (aTAM), the phenomenon of cooperation occurs when the attachment of a new tile to a growing assembly requires it to bind to more than one tile already in the assembly. Often referred to as ``temperature-2'' systems, those which employ cooperation are known to be quite powerful (i.e. they are computationally universal and can build an enormous variety of shapes and structures). Conversely, aTAM systems which do not enforce cooperative behavior, a.k.a. ``temperature-1'' systems, are conjectured to be relatively very weak, likely to be unable to perform complex computations or algorithmically direct the process of self-assembly. Nonetheless, a variety of models based on slight modifications to the aTAM have been developed in which temperature-1 systems are in fact capable of Turing universal computation through a restricted notion of cooperation. Despite that power, though, several of those models have previously been proven to be unable to perform or simulate the stronger form of cooperation exhibited by temperature-2 aTAM systems. In this paper, we first prove that another model in which temperature-1 systems are computationally universal, namely the restricted glue TAM (rgTAM) in which tiles are allowed to have edges which exhibit repulsive forces, is also unable to simulate the strongly cooperative behavior of the temperature-2 aTAM. We then show that by combining the properties of two such models, the Dupled Tile Assembly Model (DTAM) and the rgTAM into the DrgTAM, we derive a model which is actually more powerful at temperature-1 than the aTAM at temperature-2. Specifically, the DrgTAM, at temperature-1, can simulate any aTAM system of any temperature, and it also contains systems which cannot be simulated by any system in the aTAM

The Power of Duples (in Self-Assembly): It's Not So Hip To Be Square

In this paper we define the Dupled abstract Tile Assembly Model (DaTAM), which is a slight extension to the abstract Tile Assembly Model (aTAM) that allows for not only the standard square tiles, but also "duple" tiles which are rectangles pre-formed by the joining of two square tiles. We show that the addition of duples allows for powerful behaviors of self-assembling systems at temperature 1, meaning systems which exclude the requirement of cooperative binding by tiles (i.e., the requirement that a tile must be able to bind to at least 2 tiles in an existing assembly if it is to attach). Cooperative binding is conjectured to be required in the standard aTAM for Turing universal computation and the efficient self-assembly of shapes, but we show that in the DaTAM these behaviors can in fact be exhibited at temperature 1. We then show that the DaTAM doesn't provide asymptotic improvements over the aTAM in its ability to efficiently build thin rectangles. Finally, we present a series of results which prove that the temperature-2 aTAM and temperature-1 DaTAM have mutually exclusive powers. That is, each is able to self-assemble shapes that the other can't, and each has systems which cannot be simulated by the other. Beyond being of purely theoretical interest, these results have practical motivation as duples have already proven to be useful in laboratory implementations of DNA-based tiles

Producibility in Hierarchical Self-assembly

Three results are shown on producibility in the hierarchical model of tile self-assembly. It is shown that a simple greedy polynomial-time strategy decides whether an assembly α is producible. The algorithm can be optimized to use O(|α | log2 |α|) time. Cannon, Demaine, Demaine, Eisenstat, Patitz, Schweller, Summers, and Winslow [5] showed that the problem of deciding if an assembly α is the unique producible terminal assembly of a tile system T can be solved in O(|α|2|T | + |α||T |2) time for the special case of noncooperative “temperature 1” systems. It is shown that this can be improved to O(|α||T | log |T |) time. Finally, it is shown that if two assemblies are producible, and if they can be overlapped consistently – i.e., if the positions that they share have the same tile type in each assembly – then their union is also producible.

HIROIMONO Is NP-Complete

In a Hiroimono puzzle, one must collect a set of stones from a square grid, moving along grid lines, picking up stones as one encounters them, and changing direction only when one picks up a stone. We show that deciding the solvability of such puzzles is NP-complete

Hinged Dissections Exist

We prove that any finite collection of polygons of equal area has a common hinged dissection. That is, for any such collection of polygons there exists a chain of polygons hinged at vertices that can be folded in the plane continuously without self-intersection to form any polygon in the collection. This result settles the open problem about the existence of hinged dissections between pairs of polygons that goes back implicitly to 1864 and has been studied extensively in the past ten years. Our result generalizes and indeed builds upon the result from 1814 that polygons have common dissections (without hinges). Our proofs are constructive, giving explicit algorithms in all cases. For two planar polygons whose vertices lie on a rational grid, both the number of pieces and the running time required by our construction are pseudopolynomial. This bound is the best possible, even for unhinged dissections. Hinged dissections have possible applications to reconfigurable robotics, programmable matter, and nanomanufacturing.Massachusetts Institute of Technology/Akamai Presidential FellowshipNational Science Foundation (U.S.) (Graduate Research Fellowship

PERSEPSI PERAWAT MENGENAI KEBUTUHAN SPIRITUAL DAN PEMENUHAN KEBUTUHAN SPIRITUAL PASIEN DI INSTALASI GAWAT DARURAT

Patient overcrowding and rapid patient turnover in emergency department cause nurses to be less than optimal in providing patients spiritual needs. This condition can affect the emergency nurses' perceptions of spirituality and fulfill the patient's spiritual needs. The unmet of emergency patients spiritual needs can results a poor treatment. With a good perception of spirituality, nurses will have the ability to meet the patients spiritual needs. The aim of this study is to describe nurses’ perception of spiritual needs and fulfill the spiritual needs of patients in the emergency department. This study was used descriptive survey research. Samples were taken using total sampling technique and obtained 75 participants. Data were taken using the Spiritual Care Giving Scale (SCGS) questionnaire and analyzed by univariate analysis. The results showed that more than a half of emergency nurses considered spiritual needs and fulfilled the patient’s spiritual needs as very important (57,3%). Every aspect of fulfilling spiritual needs is also perceived to be very important by emergency nurses. An aspect that need to be improved are values in fulfilling spiritual needs. The value of spirituality is interpreted as a very important part of holistic nursing. Consequently, emergency nurses need to improve their understanding of spirituality so that the implementation of fulfilling patients spiritual needs in emergency department can be positively reinforced. Keywords : emergency nurse, perception, spiritua