We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

/pdf/functional-nucleic-acid-sensors-k8tlieshyr.pdf

Functional Nucleic Acid Sensors

We describe an autonomous DNA nanorobot capable of transporting molecular payloads to cells, sensing cell surface inputs for conditional, triggered activation, and reconfiguring its structure for payload delivery. The device can be loaded with a variety of materials in a highly organized fashion and is controlled by an aptamer-encoded logic gate, enabling it to respond to a wide array of cues. We implemented several different logical AND gates and demonstrate their efficacy in selective regulation of nanorobot function. As a proof of principle, nanorobots loaded with combinations of antibody fragments were used in two different types of cell-signaling stimulation in tissue culture. Our prototype could inspire new designs with different selectivities and biologically active payloads for cell-targeting tasks.

http://science.sciencemag.org/content/sci/335/6070/831.full.pdf

A logic-gated nanorobot for targeted transport of molecular payloads

Since benchmarks drive computer science research and industry product development, which ones we use and how we evaluate them are key questions for the community. Despite complex runtime tradeoffs due to dynamic compilation and garbage collection required for Java programs, many evaluations still use methodologies developed for C, C++, and Fortran. SPEC, the dominant purveyor of benchmarks, compounded this problem by institutionalizing these methodologies for their Java benchmark suite. This paper recommends benchmarking selection and evaluation methodologies, and introduces the DaCapo benchmarks, a set of open source, client-side Java benchmarks. We demonstrate that the complex interactions of (1) architecture, (2) compiler, (3) virtual machine, (4) memory management, and (5) application require more extensive evaluation than C, C++, and Fortran which stress (4) much less, and do not require (3). We use and introduce new value, time-series, and statistical metrics for static and dynamic properties such as code complexity, code size, heap composition, and pointer mutations. No benchmark suite is definitive, but these metrics show that DaCapo improves over SPEC Java in a variety of ways, including more complex code, richer object behaviors, and more demanding memory system requirements. This paper takes a step towards improving methodologies for choosing and evaluating benchmarks to foster innovation in system design and implementation for Java and other managed languages.

/pdf/the-dacapo-benchmarks-java-benchmarking-development-and-3pc03s7g9q.pdf

The DaCapo benchmarks: java benchmarking development and analysis

Recent development of solution-phase molecular-scale Boolean calculations using deoxyribozymes is potentially an important step toward the development of autonomous therapeutic and diagnostic devices. Here, the construction of basic YES, AND, ANDNOT, and ANDANDNOT deoxyribozyme-based logic gates is described. Protocols for testing gate activity using fluorescent oligonucleotide probes have been provided, and pointers for gate optimization are included.

Solution-Phase Molecular-Scale Computation With Deoxyribozyme-Based Logic Gates and Fluorescent Readouts

Molecular spiders are nanoscale walkers made with DNA enzyme legs attached to a common body. They move over a surface of DNA substrates, cleaving them and leaving behind product DNA strands, which they are able to revisit. Simple one-dimensional models of spider motion show significant superdiffusive motion when the leg-substrate bindings are longer-lived than the leg-product bindings. This gives the spiders potential as a faster-than-diffusion transport mechanism. However, analysis shows that single-spider motion eventually decays into an ordinary diffusive motion, owing to the ever increasing size of the region of cleaved products. Inspired by cooperative behavior of natural molecular walkers, we propose a symmetric exclusion process model for multiple walkers interacting as they move over a one-dimensional lattice. We show that when walkers are sequentially released from the origin, the collective effect is to prevent the leading walkers from moving too far backwards. Hence, there is an effective outward pressure on the leading walkers that keeps them moving superdiffusively for longer times, despite the growth of the product region. Multi-spider systems move faster and farther than single spiders or systems with multiple simple random walkers.

Cooperative linear cargo transport with molecular spiders

We propose a way of implementing a biomolecular computer in the laboratory using deoxyribozyme logic gates inside a microfluidic reaction chamber. We build upon our previous work, which simulated the operation of a flip-flop and an oscillator based on deoxyribozymes in a continuous stirred-tank reactor (CSTR). Unfortunately, using these logic gates in a laboratory-size CSTR is prohibitively expensive, because the reagent quantities needed are too large. This motivated our decision to design a microfluidic system. We would like to use a rotary mixer, so we examine how it operates, show how we have simulated its operation, and discuss how it affects the kinetics of the system. We then show the result of simulating both a flip-flop and an oscillator inside our rotary mixing chamber, and discuss the differences in results from the CSTR setting.

https://www.cs.unm.edu/~treport/tr/05-03/towards.pdf

Towards practical biomolecular computers using microfluidic deoxyribozyme logic gate networks

We survey common biochemical constraints useful for the design of DNA code words for DNA computation. We define the DNA Code Constraint Problem and cover biochemistry topics relevant to DNA libraries. We examine which biochemical constraints are best suited for DNA word design.

/pdf/designing-nucleotide-sequences-for-computation-a-survey-of-3fadbb2ybs.pdf

Designing nucleotide sequences for computation: a survey of constraints

Recurrent neural networks (RNN) are simple dynamical systems whose computational power has been attributed to their short-term memory. Short-term memory of RNNs has been previously studied analytically only for the case of orthogonal networks, and only under annealed approximation, and uncorrelated input. Here for the first time, we present an exact solution to the memory capacity and the task-solving performance as a function of the structure of a given network instance, enabling direct determination of the function--structure relation in RNNs. We calculate the memory capacity for arbitrary networks with exponentially correlated input and further related it to the performance of the system on signal processing tasks in a supervised learning setup. We compute the expected error and the worst-case error bound as a function of the spectra of the network and the correlation structure of its inputs and outputs. Our results give an explanation for learning and generalization of task solving using short-term memory, which is crucial for building alternative computer architectures using physical phenomena based on the short-term memory principle.

/pdf/memory-and-information-processing-in-recurrent-neural-4xp8puz4vn.pdf

Darko Stefanovic

Papers

Solution-Phase Molecular-Scale Computation With Deoxyribozyme-Based Logic Gates and Fluorescent Readouts

Cooperative linear cargo transport with molecular spiders

Towards practical biomolecular computers using microfluidic deoxyribozyme logic gate networks

Designing nucleotide sequences for computation: a survey of constraints

Memory and Information Processing in Recurrent Neural Networks