We show that the programs of any classical (as opposed to parallel or interactive) computation model or programming language that satisfies natural postulates of effectiveness (which specialize Gurevich’s Sequential Postulates) can be simulated by a random access machine (RAM) with only constant overhead. In essence, the effectiveness postulates assert the following: states can be represented a...

Oblivious RAM (ORAM) is a cryptographic primitive that allows a trusted CPU to securely access untrusted memory, such that the access patterns reveal nothing about sensitive data. ORAM is known to have broad applications in secure processor design and secure multi-party computation for big data. Unfortunately, due to a well-known logarithmic lower bound by Goldreich and Ostrovsky (Journal of th...

We introduce WORM-ORAM, a first mechanism that combines Oblivious RAM (ORAM) access privacy and data confidentiality with Write Once Read Many (WORM) regulatory data retention guarantees. Clients can outsource their database to a server with full confidentiality and data access privacy, and, for data retention, the server ensures client access WORM semantics. In general simple confidentiality a...

There have been several attempts recently at using homomorphic encryption to increase the efficiency of Oblivious RAM protocols. One of the most successful has been Onion ORAM, which achieves O(1) communication overhead with polylogarithmic server computation. However, it has a number of drawbacks. It requires a very large block size of B = Ω(log N), with large constants. Although it needs only...

In the setting of cloud computing a user wishes to delegate its data, as well as computations over this data, to a cloud provider. Each computation may read and modify the data, and these modifications should persist between computations. Minding the computational resources of the cloud, delegated computations are modeled as RAM programs. In particular, the delegated computations’ running time ...

T ypical enterprise IT environments consist of numerous independent and distributed servers, networks, and storage devices. To improve efficiency, customers increasingly seek to bring these disparate systems under one umbrella of control. Utility computing facilitates this effort by aggregating such systems into a single, centrally managed pool of resources. To adequately address user expectati...

We investigate the role of ram pressure stripping in the Virgo cluster using N-body simulations. Radial orbits within the Virgo cluster's gravitational potential are modeled and analyzed with respect to ram pressure stripping. The N-body model consists of 10 000 gas cloud complexes which can have inelastic collisions. Ram pressure is modeled as an additional acceleration on the clouds located a...

High capacity Last Level Cache (LLC) architectures have been proposed to mitigate the widening processor-memory speed gap. These LLC architectures have been realized using DRAM or SpinTransfer-Torque Random Access Memory (STT-RAM) memory technologies. It has been shown that STT-RAM LLC provides improved energy efficiency compared to DRAM LLC. However, existing STT-RAM LLC suffers from increased...

Non-volatile resistive memories, such as phase-change RAM (PRAM) and spin transfer torque RAM (STT-RAM), have emerged as promising candidates because of their fast read access, high storage density, and very low standby power. Unfortunately, in scaled technologies, high storage density comes at a price of lower reliability. In this article, we first study in detail the causes of errors for PRAM...

For ram-gill ventilators such as tunas and mackerels (family Scombridae) and billfishes (families Istiophoridae, Xiphiidae), fusions binding the gill lamellae and filaments prevent gill deformation by a fast and continuous ventilatory stream. This study examines the gills from 28 scombrid and seven billfish species in order to determine how factors such as body size, swimming speed, and the deg...