Asynchronous techniques for system-on-chip design

SoC design will require asynchronous techniques as the large parameter variations across the chip will make it impossible to control delays in clock networks and other global signals efficiently. Initially, SoCs will be globally asynchronous and locally synchronous (GALS). But the complexity of the numerous asynchronous/synchronous interfaces required in a GALS will eventually lead to entirely asynchronous solutions. This paper introduces the main design principles, methods, and building blocks for asynchronous VLSI systems, with an emphasis on communication and synchronization. Asynchronous circuits with the only delay assumption of isochronic forks are called quasi-delay-insensitive (QDI). QDI is used in the paper as the basis for asynchronous logic. The paper discusses asynchronous handshake protocols for communication and the notion of validity/neutrality tests, and completion tree. Basic building blocks for sequencing, storage, function evaluation, and buses are described, and two alternative methods for the implementation of an arbitrary computation are explained. Issues of arbitration, and synchronization play an important role in complex distributed systems and especially in GALS. The two main asynchronous/synchronous interfaces needed in GALS-one based on synchronizer, the other on stoppable clock-are described and analyzed

Asynchronous Pulse Logic

This thesis explores a new way of computing with CMOS digital circuits, single-track--handshake asynchronous pulse-logic (STAPL). These circuits are similar to quasi delay-insensitive (QDI) circuits, but the normal four-phase QDI handshake is replaced with a simpler two-phase pulsed handshake. While a delay-insensitive two-phase handshake requires complicated decoding circuits, the pulsed handshake maintains the simpler, electrically beneficial signaling senses of four-phase handshaking by using timing assumptions that are easy to meet. We cover many aspects of designing moderately large digital systems out of STAPL circuits, from the communicating-process level to the production-rule and transistor level. We study the theory of operation of pulsed asynchronous circuits, starting with simple pulse repeaters; hence we progress to a general theory of operation for pulsed asynchronous circuits. This theory is a generalization of the theory of operation of synchronous digital circuits. We then develop the family of STAPL circuits. This is a complete family of dataflow processes: the presented circuits can compute unconditionally as well as conditionally; they can also store state and arbitrate. Next, we present some aspects of automatic design-tools for compiling from a higher-level description to STAPL circuits. Many of these aspects apply equally well to tools for QDI circuits; in particular, we study boolean-simplification operations that may be used for improving the performance of slack-elastic asynchronous systems. Finally, a simple 32-bit microprocessor is presented as a demonstration that the circuits and design methods work as described. Comparisons are made, mainly with QDI asynchronous design-styles: SPICE simulations in 0.6-µm CMOS suggest that a system built out of automatically compiled STAPL circuits performs at about three times higher throughput (650--700~MHz in 0.6-µm CMOS) compared with a similar system built out of carefully hand-compiled QDI circuits; the STAPL system uses about twice the energy per operation and twice the area; in other words, the STAPL system improves on the QDI system by four to five times as measured by the Et^2 and At^2 metrics

Speed and Energy Performance of an Asynchronous MIPS R3000 Microprocessor

This paper presents the speed and energy figures for an asynchronous implementation of a MIPS R3000 microprocessor. The design is almost entirely QDI and introduces a new fine-grained pipeline. The performance figures show that this design is four times as efficient as equivalent clocked designs and that its cycle time in FO4 units compares to that of high-performance dynamic pipelines

The global repressor FliZ antagonizes gene expression by σS-containing RNA polymerase due to overlapping DNA binding specificity

FliZ, a global regulatory protein under the control of the flagellar master regulator FlhDC, was shown to antagonize σS-dependent gene expression in Escherichia coli. Thereby it plays a pivotal role in the decision between alternative life-styles, i.e. FlhDC-controlled flagellum-based motility or σS-dependent curli fimbriae-mediated adhesion and biofilm formation. Here, we show that FliZ is an abundant DNA-binding protein that inhibits gene expression mediated by σS by recognizing operator sequences that resemble the −10 region of σS-dependent promoters. FliZ does so with a structural element that is similar to region 3.0 of σS. Within this element, R108 in FliZ corresponds to K173 in σS, which contacts a conserved cytosine at the −13 promoter position that is specific for σS-dependent promoters. R108 as well as C(−13) are also crucial for DNA binding by FliZ. However, while a number of FliZ binding sites correspond to known σS-dependent promoters, promoter activity is not a prerequisite for FliZ binding and repressor function. Thus, we demonstrate that FliZ also feedback-controls flagellar gene expression by binding to a site in the flhDC control region that shows similarity only to a −10 element of a σS-dependent promoter, but does not function as a promoter

Pharmacokinetic aspects of retinal drug delivery

Drug delivery to the posterior eye segment is an important challenge in ophthalmology, because many diseases affect the retina and choroid leading to impaired vision or blindness. Currently, intravitreal injections are the method of choice to administer drugs to the retina, but this approach is applicable only in selected cases (e.g. anti-VEGF antibodies and soluble receptors). There are two basic approaches that can be adopted to improve retinal drug delivery: prolonged and/or retina targeted delivery of intravitreal drugs and use of other routes of drug administration, such as periocular, suprachoroidal, sub-retinal, systemic, or topical. Properties of the administration route, drug and delivery system determine the efficacy and safety of these approaches. Pharmacokinetic and pharmacodynamic factors determine the required dosing rates and doses that are needed for drug action. In addition, tolerability factors limit the use of many materials in ocular drug delivery. This review article provides a critical discussion of retinal drug delivery, particularly from the pharmacokinetic point of view. This article does not include an extensive review of drug delivery technologies, because they have already been reviewed several times recently. Instead, we aim to provide a systematic and quantitative view on the pharmacokinetic factors in drug delivery to the posterior eye segment. This review is based on the literature and unpublished data from the authors' laboratory.Peer reviewe

Living Labs as Open-Innovation Networks

Living labs bring experimentation out of companies’ R&D departments to real-life environments with the participation and co-creation of users, partners, and other parties. This study discusses living labs as four different types of networks characterized by open innovation: utilizer-driven, enabler-driven, provider-driven, and user-driven. The typology is based on interviews with the participants of 26 living labs in Finland, Sweden, Spain, and South Africa. Companies can benefit from knowing the characteristics of each type of living lab; this knowledge will help them to identify which actor drives the innovation, to anticipate likely outcomes, and to decide what kind of role they should play while "living labbing". Living labs are networks that can help them create innovations that have a superior match with user needs and can be upscaled promptly to the global market

UPPSALA KONSERT OCH KONGRESS : En undersökning av investeringskalkylen

Beslutet om att bygga Uppsala Konsert och Kongress har varit ett omdebatterat ämne i Uppsala där kritik har framförts mot bland annat de kalkyler som varit en del av beslutsunderlaget till investeringen. Kritiker uttryckte att om beslutsfattarna hade fått en mer rättvisande bild av intäkterna och kostnaderna, hade beslutet om att uppföra byggnaden aldrig gått igenom. Att det fanns frågetecken kring kalkylerna bekräftades av en kort genomgång av dem, då det visade sig att stora poster i den inte hade specificerats.Med bakgrund av detta är syftet att svara på frågorna på vilket sätt kalkylunderlaget för driftsverksamheten varit bristfälligt samt vad som kan ha legat bakom detta. Materialet som använts för att svara på frågorna har varit en intervju med personen som varit ansvarig för kalkylerna samt dokumenten som haft anknytning till investeringskalkylerna, i form av rapporter och verksamhetsbeskrivningar, som varit en del av beslutsunderlaget.Slutsatsen är att kalkylunderlaget för driftsverksamheten, som presenterades inför beslutet om att bygga Uppsala Konsert och Kongress, har varit bristfälligt på flera punkter och att detta kan ha påverkats av flera faktorer såsom personliga intressen och förväntningar. Detta innebar i sin tur att beslutet om att bygga Uppsala Konsert och Kongress kom att fattas på ofullständiga grunder

UPPSALA KONSERT OCH KONGRESS : En undersökning av investeringskalkylen

Beslutet om att bygga Uppsala Konsert och Kongress har varit ett omdebatterat ämne i Uppsala där kritik har framförts mot bland annat de kalkyler som varit en del av beslutsunderlaget till investeringen. Kritiker uttryckte att om beslutsfattarna hade fått en mer rättvisande bild av intäkterna och kostnaderna, hade beslutet om att uppföra byggnaden aldrig gått igenom. Att det fanns frågetecken kring kalkylerna bekräftades av en kort genomgång av dem, då det visade sig att stora poster i den inte hade specificerats.Med bakgrund av detta är syftet att svara på frågorna på vilket sätt kalkylunderlaget för driftsverksamheten varit bristfälligt samt vad som kan ha legat bakom detta. Materialet som använts för att svara på frågorna har varit en intervju med personen som varit ansvarig för kalkylerna samt dokumenten som haft anknytning till investeringskalkylerna, i form av rapporter och verksamhetsbeskrivningar, som varit en del av beslutsunderlaget.Slutsatsen är att kalkylunderlaget för driftsverksamheten, som presenterades inför beslutet om att bygga Uppsala Konsert och Kongress, har varit bristfälligt på flera punkter och att detta kan ha påverkats av flera faktorer såsom personliga intressen och förväntningar. Detta innebar i sin tur att beslutet om att bygga Uppsala Konsert och Kongress kom att fattas på ofullständiga grunder