Multidimensional subset sum problem

This thesis explores new modifications to the successful LLL approach to solving the Subset Sum problem. This work is an optimization of the matrix representation of an instance. Traditionally, the basis matrix contained only one column with set elements and the sum. In this thesis we suggest having several data columns (thus introducing multidimensionality). This allows us to reduce the size of coulmn entries which changes the complexity of the problem. Splitting the data into multiple columns greatly simplifies the task of solving the Subset Sum problem. However, other problems arise when we try to generate multiple columns. Here we try to find the optimal way to do the split and present the results. Our main goal was to try to solve the current hardest Subset Sum problem instances: the ones with density slightly greater than 1. Dramatic improvement in the rate of success was observed (up to 1500 %) compared to one- dimensional implementations

Age-related deterioration of rod vision in mice

Even in healthy individuals, aging leads to deterioration in visual acuity, contrast sensitivity, visual field, and dark adaptation. Little is known about the neural mechanisms that drive the age-related changes of the retina and, more specifically, photoreceptors. According to one hypothesis, the age-related deterioration in rod function is due to the limited availability of 11-cis-retinal for rod pigment formation. To determine how aging affects rod photoreceptors and to test the retinoid-deficiency hypothesis, we compared the morphological and functional properties of rods of adult and aged B6D2F1/J mice. We found that the number of rods and the length of their outer segments were significantly reduced in 2.5-year-old mice compared with 4-month-old animals. Aging also resulted in a twofold reduction in the total level of opsin in the retina. Behavioral tests revealed that scotopic visual acuity and contrast sensitivity were decreased by twofold in aged mice, and rod ERG recordings demonstrated reduced amplitudes of both a- and b-waves. Sensitivity of aged rods determined from single-cell recordings was also decreased by 1.5-fold, corresponding to not more than 1% free opsin in these photoreceptors, and kinetic parameters of dim flash response were not altered. Notably, the rate of rod dark adaptation was unaffected by age. Thus, our results argue against age-related deficiency of 11-cis-retinal in the B6D2F1/J mouse rod visual cycle. Surprisingly, the level of cellular dark noise was increased in aged rods, providing an alternative mechanism for their desensitization

A Security Enhancement and Proof for Authentication and Key Agreement (AKA)

In this work, we consider Authentication and Key Agreement (AKA), a popular client-server Key Exchange (KE) protocol, commonly used in wireless standards (e.g., UMTS), and widely considered for new applications. We discuss natural potential usage scenarios for AKA, attract attention to subtle vulnerabilities, propose a simple and efficient AKA enhancement, and provide its formal proof of security. The vulnerabilities arise due to the fact that AKA is not a secure KE in the standard cryptographic sense, since Client C does not contribute randomness to the session key. We argue that AKA remains secure in current deployments where C is an entity controlled by a single tamper-resistant User Identity Module (UIM). However, we also show that AKA is insecure if several Client\u27s devices/UIMs share his identity and key. We show practical applicability and efficiency benefits of such multi-UIM scenarios. As our main contribution, we adapt AKA for this setting, with only the minimal changes, while adhering to AKA design goals, and preserving its advantages and features. Our protocol involves one extra PRFG evaluation and no extra messages. We formally prove security of the resulting protocol. We discuss how our security improvement allows simplification of some of AKA security heuristics, which may make our protocol more efficient and robust than AKA even for the current deployment scenarios

Free IF: How to Omit Inactive Branches and Implement S-Universal Garbled Circuit (Almost) for Free

Two-party Secure Function Evaluation (SFE) allows two parties to evaluate a function known to both parties on their private inputs. In some settings, the input of one of the parties is the definition of the computed function, and requires protection as well. The standard solution for SFE of private functions (PF-SFE) is to rely on Universal Circuits (UC), which can be programmed to implement any circuit of size s. Recent UC optimizations report the cost of UC for s-gate Boolean circuits is \approx 5s log s. Instead, we consider garbling that allows evaluating one of a given set S of circuits. We show how to evaluate one of the circuits in S at the communication cost comparable to that of evaluating the largest circuit in S. In other words, we show how to omit generating and sending inactive GC branches. Our main insight is that a garbled circuit is just a collection of garbled tables, and as such can be reused to emulate the throw-away computation of an inactive execution branch without revealing to the Evaluator whether it evaluates active or inactive branch. This cannot be proven within the standard BHR garbled circuits framework because the function description is inseparable from the garbling by denition. We carefully extend BHR in a general way, introducing topology-decoupling circuit garbling. We preserve all existing constructions and proofs of the BHR framework, while allowing this and other future constructions which may treat garbled tables separately from function description. Our construction is presented in the semi-honest model

Topical Agenda in Public Administration of Modern Russia: The Factors of Formation

The author focuses on the formation of topical agenda in the political space of modern Russia. The article attempts to substantiate the author’s position on such aspects of the political agenda as its complex composition, the degree of effectiveness, the degree of official agenda being congruenced with real needs of social development, the problem of dominating an agenda of a certain type as an instrument of political domination

Finite element modelling of contact interaction between wheel and rail with three-layered thin coating

The stress-strain of thin multilayered coatings covered the surface of the rail is studied near the region of side contact in turning motion. The stress-strain state is studied for various geometric and mechanical coating parameters’ values. A theoretical and a finite element models are developed. Stress-strain state analysis has been made based on models developed and recommendations were given for an optimal coating parameters’ selection

Examining the role of cone-expressed RPE65 in mouse cone function

Abstract Efficient chromophore supply is paramount for the continuous function of vertebrate cone photoreceptors. It is well established that isomerization of all-trans- to 11-cis- retinoid in the retinal pigmented epithelium by RPE65 is a key reaction in this process. Mutations in RPE65 result in a disrupted chromophore supply, retinal degeneration, and blindness. Interestingly, RPE65 has recently been found to also be expressed in cone photoreceptors in several species, including mouse and human. However, the functional role of cone-expressed RPE65 has remained unknown. Here, we used loss and gain of function approaches to investigate this issue. First, we compared the function of cones from control and RPE65-deficient mice. Although we found that deletion of RPE65 partially suppressed cone dark adaptation, the interpretation of this result was complicated by the abnormal cone structure and function caused by the chromophore deficiency in the absence of RPE65 in the pigmented epithelium. As an alternative approach, we generated transgenic mice to express human RPE65 in the cones of mice where RPE65 expression is normally restricted to the pigmented epithelium. Comparison of control (RPE65-deficient) and transgenic (RPE65-expressing) cones revealed no morphological or functional changes, with only a slight delay in dark adaptation, possibly caused by the buffering of retinoids by RPE65. Together, our results do not provide any evidence for a functional role of RPE65 in mouse cones. Future studies will have to determine whether cone-expressed RPE65 plays a role in maintaining the long-term homeostasis of retinoids in cones and their function and survival, particularly in humans

Stacked Garbling: Garbled Circuit Proportional to Longest Execution Path

Secure two party computation (2PC) of arbitrary programs can be efficiently achieved using garbled circuits (GC). The bottleneck of GC efficiency is communication. It is widely believed that for direct 2PC evaluation of a Boolean circuit, it is necessary to transmit the entire GC, including garbled truth tables corresponding to subcomputations whose output is ultimately discarded by conditional logic. This folklore belief is false. We propose a novel GC technique, stacked garbling, that eliminates the communication cost of inactive conditional branches. We extend the ideas of conditional GC evaluation explored in (Kolesnikov, Asiacrypt 18) and (Heath and Kolesnikov, Eurocrypt 20). Unlike these works, ours is for general 2PC where no player knows which conditional branch is taken. Our garbling scheme, Stack, requires communication proportional to the longest execution path rather than to the entire circuit. Stack is compatible with state-of-the-art techniques, such as free XOR and half-gates. Stack is a garbling scheme. As such, it can be plugged into a variety of existing protocols, and the resulting round complexity is the same as that of standard GC. The approach does incur computation cost quadratic in the conditional branching factor vs linear in standard schemes, but the tradeoff is beneficial for most programs: GC computation even on weak hardware is faster than GC transmission on fast channels. We implemented Stack in C++. Stack reduces communication cost by approximately the branching factor: for 16 branches, communication is reduced by 10.5x. In terms of wall-clock time for circuits with branching factor 16 over a 50 Mbps WAN on a laptop, Stack outperforms state-of- the-art half-gates-based 2PC by more than 4x