Representing Fitness Landscapes by Valued Constraints to Understand the Complexity of Local Search

Local search is widely used to solve combinatorial optimisation problems and to model biological evolution, but the performance of local search algorithms on different kinds of fitness landscapes is poorly understood. Here we consider how fitness landscapes can be represented using valued constraints, and investigate what the structure of such representations reveals about the complexity of local search. First, we show that for fitness landscapes representable by binary Boolean valued constraints there is a minimal necessary constraint graph that can be easily computed. Second, we consider landscapes as equivalent if they allow the same (improving) local search moves; we show that a minimal constraint graph still exists, but is NP-hard to compute. We then develop several techniques to bound the length of any sequence of local search moves. We show that such a bound can be obtained from the numerical values of the constraints in the representation, and show how this bound may be tightened by considering equivalent representations. In the binary Boolean case, we prove that a degree 2 or treestructured constraint graph gives a quadratic bound on the number of improving moves made by any local search; hence, any landscape that can be represented by such a model will be tractable for any form of local search. Finally, we build two families of examples to show that the conditions in our tractability results are essential. With domain size three, even just a path of binary constraints can model a landscape with an exponentially long sequence of improving moves. With a treewidth-two constraint graph, even with a maximum degree of three, binary Boolean constraints can model a landscape with an exponentially long sequence of improving moves.

A minimal constraint device for imaging nuclei in live Drosophila contractile larval muscles reveals novel nuclear mechanical dynamics

Muscle contractions produce reiterated cytoplasmic mechanical variations, which potentially influence nuclear mechanotransduction, however information regarding the dynamics of muscle nuclei in the course of muscle contraction is still missing.

Pengaruh Pemberian Beberapa Bakteri Terhadap Kelangsungan Hidup Benih Ikan Lele Dumbo (Clarias sp.) [The Effect Of Bacteria Supply To Survival Rate Juvenile Of African Catfish (Clarias sp.) ]

Commodities African catfish (Clarias sp) is a rapidly growing commodity in Indonesia. Clarias gariepinus is one of the leading commodities and have a good market. African catfish hatchery fish is generally done in areas that have abundant water resources so that a minimal constraint on the area of water. Therefore applied a closed system with the addition of bacteria recirculation degrading organic material that is expected to reduce the accumulation of organic material, there by increasing the survival of African catfish fry. This study aimed to investigate the influence of bacteria that degrade organic material in a closed recirculation system on the survival of fish fry of African catfish (Clarias sp.). This research using Completely Randomized Design with four treatments and five replications of each K treatment (0%), A (1%) (6.0x108 CFU / ml), B (3%) (1.8x109 CFU / ml ) and C (5%) (3.0x109). added bacteria consisting of Pseudomonas pseudomallei with similarity index (97.81%), Pseudomonas stutzeri with similarity index (97.81%), Pseudomonas stutzeri with similarity index ( 61.21%) The results of this study indicate that the addition of Pseudomonas pseudomallei (97.81%), Pseudomonas stutzeri (97.81%) and Pseudomonas stutzeri (61.21%) gave significant differences (p <0.05) against survival of fish fry of African catfish.

Strong popular sovereignty and constitutional legitimacy

Recent critiques of attempts to ground constitutional legitimacy in the constituent power of a strong popular sovereign have tended to focus upon the tension between strong popular sovereignty and central assumptions of liberal constitutionalism. Foremost among these assumptions are the need to reconcile disagreement regarding controversial matters of common concern and the value of the rule of law. The weakness of such critiques, however, is that they presuppose a commitment to liberal principles and values that an advocate of strong popular sovereignty need not share. In this paper, I argue that recourse to liberal assumptions is unnecessary in order to demonstrate the inability of a theory of strong popular sovereignty to issue in a viable account of constitutional legitimacy. Theories of constitutional legitimacy grounded in strong popular sovereignty and constituent power, I contend, simply lack the basic resources for an adequate theory of constitutional legitimacy because they do not offer normative grounds for an assessment of whether any particular constitution is or is not legitimate. The paper is structured in three sections. Section 1 demonstrates that Carl Schmitt’s theory of constitutional legitimacy – which remains the primary source of contemporary appeals to strong popular sovereignty and constituent power – sustains a normative interpretation. Section 2 then develops a minimal constraint on an adequate normative theory of constitutional legitimacy. Finally, in Section 3, I demonstrate why a normative account of constitutional legitimacy based on strong popular sovereignty and constituent power is, at least without supplementation from normative concepts derived from a weaker conception of popular sovereignty, unable to meet this constraint.

13-Helix folding of a β/γ-peptide manifold designed from a “minimal-constraint” blueprint

A bottom-up design rationale was used to select an alternating β/γ-peptide motif which folds into a well-defined 13-helix in solution.

Choice of handedness and automated suturing for anthropomorphic dual-arm surgical robots

SUMMARYLaparoscopic and Single Port Access Surgery (SPAS) present unique dexterity challenges related to dual-arm operations in confined spaces and tele-manipulation of highly dexterous surgical slaves. In an effort to reduce tele-manipulation burden, new paradigms for semi-automating surgical tasks are needed. This paper presents a new minimal constraint suturing and automated choice of handedness for anthropomorphic dual-arm robots. The automated choice of handedness supports surgeons during tele-manipulation of complex robotic slaves where dexterity and workspace constraints are difficult to learn. This criterion is also used to support automated dual-arm rendezvous for quicker suture exchange during dual-arm suturing. The minimal constraint algorithm presented in this paper allows surgeons to operate within a shared-control tele-manipulation framework whereby the surgeon controls the needle insertion speed and the robot controls the needle orientation while respecting a minimalistic set of tissue constraints. This framework is evaluated on a novel insertable robotic end-effectors platform for SPAS. A simulation study demonstrates the effectiveness of the automated choice of handedness criterion through a study of dexterity limitations of each arm. Additional simulations show the proposed algorithm for automated rendezvous and suture exchange.