Isaiah and the computer: A preliminary report

In the eighth century B.C.E. there lived in Jerusalem a prophet of royal descent whose name was Isaiah ben Amoż. His oracles, mostly in poetry, are concerned with the contemporary political scene dominated by the Assyrians, with the fate of the Jewish people in history in general, with the mutual relationship between God and Man, and with the ultimate fate of Mankind in the fullness of time. For Jews, these oracles are perhaps second in importance only to the Pentateuch. For Christians, they are of greatest relevance because no other book influenced Jesus to the same extent. And for humanity they are so much the expression of an idealistic Weltanschauungthat they are quoted wherever educators and statesmen try to imbue their audiences with the vision of, and the hope for, a better world. They are collected in sixty-six chapters, constituting the first and longest book of the “Latter Prophets.” The project was funded by the Technion and by the Israel Academy of Sciences and Humanities, Jerusalem.     

State of the art review of inspection technologies for condition assessment of water pipes

This paper reviews the state-of-the-art of inspection techniques and technologies towards condition assessment of water distribution and transmission mains. Pipe condition assessment is the determination of its current condition, including structural health, impact on water quality, and hydraulic capacity. The collection and analysis of relevant data and information is the first and a paramount step to detect and monitor critical indicators to prevent or mitigate catastrophic failures. The technologies include conventional non-destructive inspection and advanced sensor techniques for condition monitoring. This paper focuses on the inspection techniques and technologies for structural deterioration of water pipes. Technologies like smart pipe, augmented reality, and intelligent robots are also briefly discussed and summarized.     

Session-Key Generation Using Human Passwords Only

We present session-key generation protocols in a model where the legitimate parties share only a human-memorizable password, and there is no additional set-up assumption in the network. Our protocol is proven secure under the assumption that enhanced trapdoor permutations exist. The security guarantee holds with respect to probabilistic polynomial-time adversaries that control the communication channel (between the parties), and may omit, insert, and modify messages at their choice. Loosely speaking, the effect of such an adversary that attacks an execution of our protocol is comparable with an attack in which an adversary is only allowed to make a constant number of queries of the form "is w the password of Party A." We stress that the result holds also in case the passwords are selected at random from a small dictionary so that it is feasible (for the adversary) to scan the entire directory. We note that prior to our result, it was not known whether or not such protocols were attainable without the use of random oracles or additional set-up assumptions.     

Influence of Obstacles on the Development of Gravity Current Prior to Backdraft

The phenomenon of backdraft is closely linked to the formation of a flammable region due to the mixing process between the unburned gases accumulated in the compartment and the fresh air entering the compartment through a recently created opening. The flow of incoming fresh air is called the gravity current. Gravity current prior to backdraft has already been studied, Fleischmann (1993, Backdraft phenomena, NIST-GCR-94-646. University of California, Berkeley) and Fleischmann (1999, Numerical and experimental gravity currents related to backdrafts, Fire Safety Journal); Weng et al. (2002, Exp Fluids 33:398–404), but all simulations and experiments found in the current literature are systematically based on a perfectly regular volume, usually parallelipedic in shape, without any piece of furniture or equipment in the compartment. Yet, various obstacles are normally found in real compartments and the question is whether they affect the gravity current velocity and the level of mixing between fresh and vitiated gases. In the work reported here, gravity current prior to backdraft in compartment with obstacles is investigated by means of three-dimensional CFD numerical simulations. These simulations use as a reference case the backdraft experiment test carried out by Gojkovic (2000, Initial Backdraft. Department of Fire Safety Engineering, Lunds Tekniska Högskola Universitet, Report 3121). The Froude number, the transit time and the ignition time are obtained from the computations and compared to the tests in order to validate the model.     

General Composition and Universal Composability in Secure Multiparty Computation

Concurrent general composition relates to a setting where a secure protocol is run in a network concurrently with other, arbitrary protocols. Clearly, security in such a setting is what is desired, or even needed, in modern computer networks where many different protocols are executed concurrently. Canetti (FOCS 2001) introduced the notion of universal composability and showed that security under this definition is sufficient for achieving concurrent general composition. However, it is not known whether or not the opposite direction also holds. Our main result is a proof that security under concurrent general composition, when interpreted in the natural way under the simulation paradigm, is equivalent to a variant of universal composability, where the only difference relates to the order of quantifiers in the definition. (In newer versions of universal composability, these variants are equivalent.) An important corollary of this theorem is that existing impossibility results for universal composability (for all its variants) are inherent for definitions that imply security under concurrent general composition, as formulated here. In particular, there are large classes of two-party functionalities for which it is impossible to obtain protocols (in the plain model) that remain secure under concurrent general composition. We stress that the impossibility results obtained are not “black-box,” and apply even to non-black-box simulation. Our main result also demonstrates that the definition of universal composability is somewhat “minimal” in that the composition guarantee provided by universal composability implies the definition itself. This indicates that the security definition of universal composability is not overly restrictive. An extended abstract of this work appeared in the 44th FOCS, 2003. Yehuda Lindell: Most of this work was carried out while the author was at the IBM T.J. Watson Research Center.     

Lower Bounds and Impossibility Results for Concurrent Self Composition

In the setting of concurrent self composition, a single protocol is executed many times concurrently in a network. In this paper, we prove lower bounds and impossibility results for secure protocols in this setting. First and foremost, we prove that there exist large classes of functionalities that cannot be securely computed under concurrent self composition, by any protocol. We also prove a communication complexity lower bound on protocols that securely compute a large class of functionalities in this setting. Specifically, we show that any protocol that computes a functionality from this class and remains secure for m concurrent executions, must have bandwidth of at least m bits. The above results are unconditional and hold for any type of simulation (i.e., even for non-black-box simulation). In addition, we prove a severe lower bound on protocols that are proven secure using black-box simulation. Specifically, we show that any protocol that computes the blind signature or oblivious transfer functionalities and remains secure for m concurrent executions, where security is proven via black-box simulation, must have at least m rounds of communication. Our results hold for the plain model, where no trusted setup phase is assumed. While proving our impossibility results, we also show that for many functionalities, security under concurrent self composition (where a single secure protocol is run many times) is actually equivalent to the seemingly more stringent requirement of security under concurrent general composition (where a secure protocol is run concurrently with other arbitrary protocols). This observation has significance beyond the impossibility results that are derived by it for concurrent self composition. This paper combines results that appeared in extended abstracts in Lindell (35th STOC, pp. 683–692, 2003; 1st Theory of Cryptography Conference (TOC), LNCS, vol. 2951, pp. 203–222, 2004).     

Relationship between initial competence and ability to profit from cues in brain-damaged individuals.

To study the relationships between competence and ability to profit from cues, the effects of premorbid education on current test performances, and whether the ability to profit from cues is uniform across tasks in brain-damaged persons, 62 left hemiplegics were tested consecutively on the WAIS Block Design (BD) and Similarities (SIM) tests, under standard and specially designed cuing conditions. Results indicate that the ability to profit from cues is a linear function of competence levels in both tasks. In BD, premorbid education was unrelated to either competence or cues gain. In SIM, education correlated with current competence but not with cues. No relationship was found between ability to gain from cues across tasks. Some significant clinical and theoretical implications from the data are discussed. (37 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of arbitrary defects in photonic crystals by use of the source-model technique

A novel method derived from the source-model technique is presented to solve the problem of scattering of an electromagnetic plane wave by a two-dimensional photonic crystal slab that contains an arbitrary defect (perturbation). In this method, the electromagnetic fields in the perturbed problem are expressed in terms of the field due to the periodic currents obtained from a solution of the corresponding unperturbed problem plus the field due to yet-to-be-determined correction current sources placed in the vicinity of the perturbation. Appropriate error measures are suggested, and a few representative structures are presented and analyzed to demonstrate the versatility of the proposed method and to provide physical insight into waveguiding and defect coupling mechanisms typical of finite-thickness photonic crystal slabs.