A true concurrent model of smart contracts executions

The development of blockchain technologies has enabled the trustless execution of so-called smart contracts, i.e. programs that regulate the exchange of assets (e.g., cryptocurrency) between users. In a decentralized blockchain, the state of smart contracts is collaboratively maintained by a peer-to-peer network of mutually untrusted nodes, which collect from users a set of transactions (representing the required actions on contracts), and execute them in some order. Once this sequence of transactions is appended to the blockchain, the other nodes validate it, re-executing the transactions in the same order. The serial execution of transactions does not take advantage of the multi-core architecture of modern processors, so contributing to limit the throughput. In this paper we propose a true concurrent model of smart contract execution. Based on this, we show how static analysis of smart contracts can be exploited to parallelize the execution of transactions.Comment: Full version of the paper presented at COORDINATION 202

What might it mean to democratize school reform?

Celem edukacji jest przygotowanie jednostek do życia w nowym świecie globalnych połączeń, konkurencji i rynku pracy za pomocą procesów edukacyjnych, które umożliwiają studentom bycie przygotowanymi do aktywności, odpowiedzialności i deliberacji. Z tego to powodu szkoły i nauczyciele są w centrum uwagi. Wiele reform polega na ograniczaniu autonomii szkół. Odbieranie nauczycielom prawa do decydowania, patrzenie na poprawę szkoły z perspektywy programów, które ograniczają nauczycieli do osób odczytujących polecenia i scenariusze oraz nakazują kolejne działania, a także w coraz większym stopniu przekazują kontrolę do urzędów centralnych, to nie nowe zjawiska. Ostatnio coraz silniej nauczyciele rozpoznawani są jako niezbędni liderzy szkolnych zmian. W jaki sposób osoby pracujące na uniwersytetach mogą podjąć wysiłek dla zmiany sytuacji w szkołach. Zamiast krótkich i prostych reform i programów, które znane są z tego, że w porównaniu z programami długofalowymi mają niewielki wpływ, nasza praca ze szkołami powinna opierać się na relacjach profesjonalnych. Demokratyczna reforma szkoły jest możliwa. Pracując, aby połączyć szkoły, uniwersytety i społeczności w zaangażowane sieci wsparcia, możemy doprowadzić do wzmocnienia efektów i sukcesu reform w sposób, który umożliwi inspirowanie uczniów, nauczycieli, uniwersytetów i całych społeczeństw.The goal of education is to prepare individuals for the new world of global connections, competition and the labor market by means of an educational process that works to get students ready for activity, responsibility and deliberation. Within these issues schools and teachers are the focus of much concern. Many reform efforts work to remove autonomy from the school. “Deskilling,” viewing school improvement through the lens of packaged programs that work to script teachers, prescribe what they should do in their context, and pull more and more control to central authorities, is not a new phenomenon. Recently, however, teachers have been recognized as necessary leaders in school reform. How might those based in universities proceed to work and change the situation we find in schools? Rather than one-shot, one-way school reform efforts and programs which are known to have little impact compared to long-term, collegial work, our work with schools should be based on building professional relationships. Democratic school reform is possible. By working (as it was mentioned) to link schools, universities and communities in engaged, reciprocal, networks of support we can strengthen the outcomes and the success of school reform in ways that lift up students, teachers, communities, universities and democratic societies themselves

Short term synaptic depression model—Analytical solution and analysis

In this article we present analytical solutions of the single and pair pulse time evolution of a plastic neocortical synapse described by the TM-model. We show that this model is equivalent to the receptor-desensitization model with three kinetic states. For the TM-model we derive the analytical form of a measure of paired pulse depression. We analyze the sensitivity of the synaptic depression phenomenon on model parameters and derive the relative importance of each of the parameters. The closed form of the measure of synaptic depression allows fitting the model to experimental data. The fitted parameters are used to make predictions about the asymptotic properties of the postsynaptic currents. We show that for synapses with the ratio of inactivation and recovery rates of the same order, the synaptic depression does not preclude the rate-coding of information: e.g. in the pyramid–pyramid connections of adult rat neocortex, rate-coding is possible for higher frequencies

Conversations, dialog and deliberation : leaders moving towards the democratization of school reform

This work emerged over the course of the conference, Re/forming Education: Linking Schools, Universities and Communities for Democratic School Reform. During sessions held as part of the conference, participants were asked to engage in dialog about the issues presented. These dialog sessions, held most often in small groups, included note taking and group writing. As a result, this piece is the product of the multiple voices (Superintendent, Principal, Professor, Non-governmental Organizations) present during the conference. While the piece in no way reflects the complete thoughts of one individual, it does share some of the essence of the deliberation that occurred

Preliminary studies of frozen gravel properties related to underground mining

1. Introduction -- 2. Literature review -- 3. Testing -- 3.1. Description of material used -- 3.2. Sample preparation -- 3.3. Uniaxial compressive tests -- 3.3.1. Testing procedure and test results -- 3.3.2. Conclusions -- 3.4. Water jet cutting tests -- 3.4.1. Equipment used -- 3.4.2. Test procedures -- 3.4.3. Details of test parameters -- 3.4.4. Range of parameters tested -- 3.4.5. Test results -- 3.4.6. Conclusions regarding jet cutting tests -- 4. Final remarks and conclusions -- References.This report describes research conducted by Drs. Frank J. Skudrzyk, Clark R. Barker and Marian Mazurkiewicz over a period of time from February 15 to April 15, 1982 for the University of Alaska, Fairbanks. The scope of the project, established through discussions with Dr. Chris Lambert, representing the UA, was to conduct pilot studies of frozen gravel properties related to underground mining in permafrost: high pressure water jet cutting characteristics and uniaxial compressive test (uniaxial compressive strength and Young's modulus measurement). It has been agreed that the tests would be conducted on an artificial material simulating the frozen gravel

What Might it Mean to Democratize School Reform?

The goal of education is to prepare individuals for the new world of global connections, competition and the labor market by means of an educational process that works to get students ready for activity, responsibility and deliberation. Within these issues schools and teachers are the focus of much concern. Many reform efforts work to  remove autonomy from the school. “Deskilling,” viewing school improvement through the lens of packaged programs that work to script teachers, prescribe what they should do in their context, and pull more and more control to central authorities, is not a new phenomenon. Recently, however, teachers have been recognized as necessary leaders in school reform.How might those based in universities proceed to work and change the situation we find in schools? Rather than one-shot, one-way school reform efforts and programs which are known to have little impact compared to long-term, collegial work, our work with schools should be based on building professional relationships. Democratic school  reform is possible. By working (as it was mentioned) to link schools, universities and communities in engaged, reciprocal, networks of support we can strengthen the outcomes and the success of school reform in ways that lift up students, teachers, communities, universities and democratic societies themselves

Multiple Pulsejet Boring Device

A method and device for boring a hole [5] through a material along a desired path includes an umbilical subsystem [2000] connected to a boring subsystem [3000] having a plurality of pulsejets [3100]. These pulsejets [3100] repeatedly receive and ignite a combustible fluid [7] in a combustion chamber [3230] causing a portion of the fluid [7] to be forced out of a nozzle [3260] at high speeds as a fluid slug [10] that impacts materials ahead of the pulsejet [3100]. A controller [3310] controls the amount of fluid provided to each pulsejet [3100], and the firing timing, thereby controlling the intensity in which each slug [10] impacts the material. By modulating the intensity and firing sequence of each of the pulsejets [3100], material ahead of the boring subsystem [3000] is differentially bored thereby allowing steering of the boring subsystem [3000]

System for Rapidly Boring Through Materials

The present invention is a self-contained, high-energy liquid rock-boring system that will bore a small-diameter access hole [5] several hundred meters through hard granite and other obstacles within minutes of deployment. It employs a land unit [100] platform subsystem [1000] with an energetic fluid fuel reservoir [1300] and a boring subsystem [3000] having a plurality of pulsejets [3100]. Each pulsejet [3100] repeatedly ignites the energetic fluid [7] causing a plurality of rapidly-expanding gas bubbles [3250] which create and force a plurality liquid slugs [10] ahead of them rapidly out through a nozzle [3260] causing the slugs [10] to impact against materials ahead of the nozzles [3260], boring an access hole [5]. The system also employs an umbilical subsystem [2000] connecting the boring [3000] and the platform subsystems [1000]. The system can be used to rapidly bore an access hole [5] to provide air and resources to trapped miners. Alternatively, the system may also be used to bore an access hole [5] to underground threatening targets to neutralize them