Theoretical Cryptanalysis of the Klimov-Shamir Number Generator TF-1

The internal state of the Klimov-Shamir number generator TF-1 consists of four words of size w bits each, whereas its intended strength is 2^2w. We exploit an asymmetry in its output function to show that the internal state can be recovered after having 2^w outputs, using 2^1.5w operations. For w = 32 the attack is practical, but for their recommended w = 64 it is only of theoretical interest.     

耶路撒冷森林橄榄园休闲区

农业景观具有超越生产的价值。在以色列,自圣经时代开始,橄榄园就是根植于民间传说、历史与文化的景观。如今,以色列的人口密度不断增长,导致开放景观空间和农业区的大大减少。人口压力紧随着农业技术的进步,虽然提高了生产力,两者却共同导致我们熟知和珍惜的农业景观日趋罕见,而农业景观一直以来都是以色列文化的一部分。因此,当古兰尼建筑被委托设计一座橄榄园再利用于休闲时,他们的主要目标便是保留橄榄园的气氛和形式。老露台石墙由散落在现场的石块重建,用于休憩的座椅区被设计为露台墙的一部分。石头露台墙是该地区栽种橄榄树林的典型方式。石块收集于土地清理,石头挡土墙有利于保护倾斜的土地,尤其是在表层土壤薄且珍贵的情况下。传统的做法是将石块单     

Local urban growth controls and regional economic growth

Local land use regulations have been adopted to restrict population growth and urban sprawl in an attempt to prevent future problems like congestion, pollution, and loss of open space. However, when regulations become widespread in a region, it can be difficult for young workers and newcomers to find appropriate housing in the region. Because local governments may neglect the effects of their policies on the rest of the region, the resulting population size can be inefficient. We show that local adoption of housing regulations tends to over-restrict population growth when there are strong agglomeration economies in the regional production. On the other hand, when there is congestion in production, coordination among jurisdictions is undesirable if business interests are neglected.     

Validation of daily growth of African catfish Clarias gariepinus (Burchell 1822) young‐of‐the‐year from Lake Baringo,Kenya

The African catfish (Clarias gariepinus) is widely distributed in Africa, where it is a major food fish. The species comprises a significant component of commercial fishery landings in Kenya, and elsewhere in Africa. Nevertheless, little information or data exist on its age and growth characteristics, which is necessary for its sustainable management. This study determined this information from the microstructure of lapillar otoliths of the young‐of‐the‐year (YOY) of the species. Analysis of the otolith microstructure from fish of known age confirmed that one growth increment (circulus) was formed per day, forming the basis for their use to accurately age C. gariepinus YOY collected from Lake Baringo during the months of August and September 2007. The derived length–age relationship correlated significantly (Pearson Correlation, df = 53, P < 0.05), indicating that the YOY exhibited an average growth rate of 0.2285 cm day^?1. The largest specimen attained a total length of 40.5 cm in only 169 days. These results indicate that native C. gariepinus exhibits rapid growth, achieving a large size during the first year. Thus, they can be recommended for purposes of aquaculture.     

Fast generators for the Diffie-Hellman key agreement protocol and malicious standards

The Diffie-Hellman key agreement protocol is based on taking large powers of a generator of a prime-order cyclic group. Some generators allow faster exponentiation. We show that to a large extent, using the fast generators is as secure as using a randomly chosen generator. On the other hand, we show that if there is some case in which fast generators are less secure, then this could be used by a malicious authority to generate a standard for the Diffie-Hellman key agreement protocol which has a hidden trapdoor.     

A Comparison of State-of-the-Art Classification Techniques with Application to Cytogenetics

Several state-of-the-art techniques – a neural network, Bayesian neural network, support vector machine and naive Bayesian classifier – are experimentally evaluated in discriminating fluorescence   in situ hybridisation (FISH) signals. Highly-accurate classification of valid signals and artifacts of several cytogenetic probes (colours) is required for detecting abnormalities in FISH images. More than 3100 FISH signals are classified by each of the techniques into colour and as real or artifact with accuracies of around 98% and 88%, respectively. The results of the comparison also show a trade-off between simplicity represented by the naive Bayesian classifier, and high classification performance represented by the other techniques.     

Segmentation and classification of dot and non-dot-like fluorescence in situ hybridization signals for automated detection of cytogenetic abnormalities.

Signal segmentation and classification of fluorescence in situ hybridization (FISH) images are essential for the detection of cytogenetic abnormalities. Since current methods are limited to dot-like signal analysis, we propose a methodology for segmentation and classification of dot and non-dot-like signals. First, nuclei are segmented from their background and from each other in order to associate signals with specific isolated nuclei. Second, subsignals composing non-dot-like signals are detected and clustered to signals. Features are measured to the signals and a subset of these features is selected representing the signals to a multiclass classifier. Classification using a naive Bayesian classifier (NBC) or a multilayer perceptron is accomplished. When applied to a FISH image database, dot and non-dot-like signals were segmented almost perfectly and then classified with accuracy of approximately 80% by either of the classifiers.     

Optimal smoothing schedules for real-time streams

We consider the problem of smoothing real-time streams (such as video streams), where the goal is to reproduce a variable-bandwidth stream remotely, while minimizing bandwidth cost, space requirement, and playback delay. We focus on lossy schedules, where data may be dropped due to limited bandwidth or space. We present the following results. First, we determine the optimal tradeoff between buffer space, smoothing delay, and link bandwidth for lossy smoothing schedules. Specifically, this means that if two of these parameters are given, we can precisely calculate the value for the third which minimizes data loss while avoiding resource wastage. The tradeoff is accomplished by a simple generic algorithm, that allows one some freedom in choosing which data to discard. This algorithm is very easy to implement both at the server and at the client, and it enjoys the nice property that only the server decides which data to discard, and the client needs only to reconstruct the stream.In a second set of results we study the case where different parts of the data have different importance, modeled by assigning a real weight to each packet in the stream. For this setting we use competitive analysis, i.e., we compare the weight delivered by on-line algorithms to the weight of an optimal off-line schedule using the same resources. We prove that a natural greedy algorithm is 4-competitive. We also prove a lower bound of 1.23 on the competitive ratio of any deterministic on-line algorithm. Finally, we give a few experimental results which seem to indicate that smoothing is very effective in practice, and that the greedy algorithm performs very well in the weighted case.Received: 21 November 2001, Accepted: 6 November 2003, Published online: 6 February 2004Research supported in part by Israel Ministry of Science. An extended abstract of this paper appeared in Proc. 19th ACM Symp. on Principles of Distributed Computing, July 2000.     

Excessive software development: Practices and penalties

This study focuses on the tendency to develop software excessively, above and beyond need or available development resources. The literature pays little attention to this issue, overlooking its crucial impact and penalties. Terms used in reference to excessive software development practices include over-requirement, over-specification, over-design, gold-plating, bells-and-whistles, feature creep, scope creep, requirements creep, featuritis, scope overload and over-scoping. Some of these terms share the same meaning, some overlap, some refer to the development phase, and some to the final system. Via a systematic literature search, we first demonstrate the poor state of research about excessive software development practices in the information systems and project management areas. Then, we suggest a framework consolidating the problems associated with excessive software development in three ‘beyond’ categories (beyond needs, beyond resources, beyond plans), describe and analyze their causes, consequences, boundaries and overlapping zones. Finally, we discuss the findings and present directions for future research.