Uniformity is weaker than semi-uniformity for some membrane systems

We investigate computing models that are presented as families of finite computing devices with a uniformity condition on the entire family. Examples of such models include Boolean circuits, membrane systems, DNA computers, chemical reaction networks and tile assembly systems, and there are many others. However, in such models there are actually two distinct kinds of uniformity condition. The first is the most common and well-understood, where each input length is mapped to a single computing device (e.g. a Boolean circuit) that computes on the finite set of inputs of that length. The second, called semi-uniformity, is where each input is mapped to a computing device for that input (e.g. a circuit with the input encoded as constants). The former notion is well-known and used in Boolean circuit complexity, while the latter notion is frequently found in literature on nature-inspired computation from the past 20 years or so. Are these two notions distinct? For many models it has been found that these notions are in fact the same, in the sense that the choice of uniformity or semi-uniformity leads to characterisations of the same complexity classes. In other related work, we showed that these notions are actually distinct for certain classes of Boolean circuits. Here, we give analogous results for membrane systems by showing that certain classes of uniform membrane systems are strictly weaker than the analogous semi-uniform classes. This solves a known open problem in the theory of membrane systems. We then go on to present results towards characterising the power of these semi-uniform and uniform membrane models in terms of NL and languages reducible to the unary languages in NL, respectively.Comment: 28 pages, 1 figur

AND and/or OR: Uniform Polynomial-Size Circuits

We investigate the complexity of uniform OR circuits and AND circuits of polynomial-size and depth. As their name suggests, OR circuits have OR gates as their computation gates, as well as the usual input, output and constant (0/1) gates. As is the norm for Boolean circuits, our circuits have multiple sink gates, which implies that an OR circuit computes an OR function on some subset of its input variables. Determining that subset amounts to solving a number of reachability questions on a polynomial-size directed graph (which input gates are connected to the output gate?), taken from a very sparse set of graphs. However, it is not obvious whether or not this (restricted) reachability problem can be solved, by say, uniform AC^0 circuits (constant depth, polynomial-size, AND, OR, NOT gates). This is one reason why characterizing the power of these simple-looking circuits in terms of uniform classes turns out to be intriguing. Another is that the model itself seems particularly natural and worthy of study. Our goal is the systematic characterization of uniform polynomial-size OR circuits, and AND circuits, in terms of known uniform machine-based complexity classes. In particular, we consider the languages reducible to such uniform families of OR circuits, and AND circuits, under a variety of reduction types. We give upper and lower bounds on the computational power of these language classes. We find that these complexity classes are closely related to tallyNL, the set of unary languages within NL, and to sets reducible to tallyNL. Specifically, for a variety of types of reductions (many-one, conjunctive truth table, disjunctive truth table, truth table, Turing) we give characterizations of languages reducible to OR circuit classes in terms of languages reducible to tallyNL classes. Then, some of these OR classes are shown to coincide, and some are proven to be distinct. We give analogous results for AND circuits. Finally, for many of our OR circuit classes, and analogous AND circuit classes, we prove whether or not the two classes coincide, although we leave one such inclusion open.Comment: In Proceedings MCU 2013, arXiv:1309.104

Simulating counting oracles with cooperation

We prove that monodirectional shallow chargeless P systems with active membranes and minimal cooperation working in polynomial time precisely characterise P#P k , the complexity class of problems solved in polynomial time by deterministic Turing machines with a polynomial number of parallel queries to an oracle for a counting problem

Computational Complexity Theory in Membrane Computing: Seventeen Years After

In this work we revisit the basic concepts, definitions of computational complexity theory in membrane computing. The paper also discusses a novel methodology to tackle the P versus NP problem in the context of the aforementioned theory. The methodology is illustrated with a collection of frontiers of tractability for several classes of P systems.Ministerio de Economía, Industria y Competitividad TIN2017-89842-

Remarks on the Computational Power of Some Restricted Variants of P Systems with Active Membranes

In this paper we consider three restricted variants of P systems with active membranes: (1) P systems using out communication rules only, (2) P systems using elementary membrane division and dissolution rules only, and (3) polarizationless P systems using dissolution and restricted evolution rules only. We show that every problem in P can be solved with uniform families of any of these variants. This, using known results on the upper bound of the computational power of variants (1) and (3) yields new characterizations of the class P. In the case of variant (2) we provide a further characterization of P by giving a semantic restriction on the computations of P systems of this varian

Modification of a Substrate Roughness for a Fabrication of Freestanding Electroplated Metallic Microstructures

This study aims to demonstrate a simple fabrication technique of freestanding electroplated metallic microstructures by modifying a substrate roughness. The proposed technique utilizes counter effects between two forces, i.e. an intrinsic force causing shrinkage in an electroplated metallic microstructure, and an adhesive force adhering a metallic microstructure to a substrate. With the modification of substrate roughness until the adhesive force becomes weaker than the induced intrinsic force, electroplated metallic microstructures would spontaneously release from the substrate after the electroplating process. Three parameters, i.e. substrate roughness, electroplated square structure's area and electroplated rectangular structure's width-to-length ratio, were experimentally studied. The results showed that the electroplated structure with a smaller size and smaller width-to-length ratio was more easily detached from the substrate for a given substrate roughness. In addition, for the same electroplated structure, a substrate with less roughness allowed a detachment of electroplated microstructure more easily

Implantable Drug Delivery Systems

Traditional drug delivery methods provide very little, if any, control over the timing and pattern of drug release Medication concentration absorption at the point of action. Undefined medication concentration in plasma is a typical and obvious issue with the traditional dose method. Thus to overcome such problems efforts have been made by researchers and pharmaceutical scientists to the betterment of the drug delivery system and that lead to the development of the Novel Drug Delivery System (NDDS). NDDS is the approach and technology to deliver the drug in low concentration and follow the zero-order release of the drug in a controlled manner. Additionally, the NDDS's development results in the creation of an implantable drug delivery system (IDDS). a system for implantable medication delivery is a new approach of medicine delivery In this technique, the medicine is delivered under controlled conditions to the precise location where the implant is placed. The formulation, preparation, evaluation criteria, and future aspects of the implantable drug delivery system are the subjects of this study

Piezoresistant probe for measurement of velocity in one-dimensional incompressible flow

Radeći na problemu kalibracije sondi sa zagrejanim vlaknima u okviru rada [3], javila se potreba za sondom kojom se može meriti trenutna brzina u jednodimenzijskom vazdušnom mlazu. Ubrzo potom na Mašinskom fakultetu u Beogradu je razrađena ideja o prvoj domaćoj piezorezistivnoj sondi kojom se meri trenutni diferencijalni pritisak. Sonda je realizovana u saradnji sa IHTM, Centrom za mikroelektronske tehnologije i monokristale. Probna ispitivanja su pokazala da se sonda može uspešno koristiti za merenje trenutne brzine jednodimenzijskog nestišljivog strujanja. U tom smislu je posle prvenac sonde napravljeno još nekoliko sličnih sondi. U radu su dati osnovni elementi tehnološkog postupka za dobijanje senzora pritiska. Pored detaljnog opisa senzorskog čipa ovde su prikazani i drugi elementi sonde JR-p. Pre svakog merenja sondom ona mora da se baždari. Sonda JR-p se baždari statički i u kvazistacionarnom vazdušnom mlazu. Ovde su prikazani rezultati jednog takvog baždarenja.Working on the problem of calibration of hot wire probes within (3), we came to the need to have a probe for measuring the instantaneous velocity in a one-dimensional air jet. Soon after the idea concerned with the first domestic piezoresistant probe by means of which the instantaneous differential pressure can be measured was developed on the Faculty of Mechanical Engineering. The probe was realized in the collaboration with IHTM, the Center for microelectronic technology and monocrystals. First tests with the probe showed that it could be successfully used for measuring the instantaneous velocity in one-dimensional incompressible flows. In that sense, some more similar probes were produced after the pioneering one. In this paper the basic elements of the technological procedure for the production of the pressure sensor are given. In addition to a detailed description of the sensor chip we show here some other elements of the probe JR-p also. Before any use the probe must be calibrated. The probe JR-p is calibrated statically in a quasi-steady air jet. The results of such a calibration are presented here

Piezoresistant probe for measurement of velocity in one-dimensional incompressible flow

Radeći na problemu kalibracije sondi sa zagrejanim vlaknima u okviru rada [3], javila se potreba za sondom kojom se može meriti trenutna brzina u jednodimenzijskom vazdušnom mlazu. Ubrzo potom na Mašinskom fakultetu u Beogradu je razrađena ideja o prvoj domaćoj piezorezistivnoj sondi kojom se meri trenutni diferencijalni pritisak. Sonda je realizovana u saradnji sa IHTM, Centrom za mikroelektronske tehnologije i monokristale. Probna ispitivanja su pokazala da se sonda može uspešno koristiti za merenje trenutne brzine jednodimenzijskog nestišljivog strujanja. U tom smislu je posle prvenac sonde napravljeno još nekoliko sličnih sondi. U radu su dati osnovni elementi tehnološkog postupka za dobijanje senzora pritiska. Pored detaljnog opisa senzorskog čipa ovde su prikazani i drugi elementi sonde JR-p. Pre svakog merenja sondom ona mora da se baždari. Sonda JR-p se baždari statički i u kvazistacionarnom vazdušnom mlazu. Ovde su prikazani rezultati jednog takvog baždarenja.Working on the problem of calibration of hot wire probes within (3), we came to the need to have a probe for measuring the instantaneous velocity in a one-dimensional air jet. Soon after the idea concerned with the first domestic piezoresistant probe by means of which the instantaneous differential pressure can be measured was developed on the Faculty of Mechanical Engineering. The probe was realized in the collaboration with IHTM, the Center for microelectronic technology and monocrystals. First tests with the probe showed that it could be successfully used for measuring the instantaneous velocity in one-dimensional incompressible flows. In that sense, some more similar probes were produced after the pioneering one. In this paper the basic elements of the technological procedure for the production of the pressure sensor are given. In addition to a detailed description of the sensor chip we show here some other elements of the probe JR-p also. Before any use the probe must be calibrated. The probe JR-p is calibrated statically in a quasi-steady air jet. The results of such a calibration are presented here

Characterising the complexity of tissue P systems with fission rules

We analyse the computational efficiency of tissue P systems, a biologically-inspired computing device modelling the communication between cells. In particular, we focus on tissue P systems with fission rules (cell division and/or cell separation), where the number of cells can increase exponentially during the computation. We prove that the complexity class characterised by these devices in polynomial time is exactly P^#P, the class of problems solved by polynomial-time Turing machines with oracles for counting problems