Speeding up Exponentiation using an Untrusted Computational Resource

We present protocols for speeding up fixed-base variable-exponent exponentiation and variable-base fixed-exponent exponentiation using an untrusted computational resource. In the fixed-base protocols, the exponent may be blinded. In the variable-base protocols, the base may be blinded. The protocols are described for exponentiation in a cyclic group. We describe how to extend them to exponentiation modulo an integer where the modulus is the product of primes with single multiplicity. The protocols provide a speedup of over the square-and-multiply algorithm, where k is the bitlength of the exponent. One application of the protocols is to speed up exponentiation-based verification in discrete log-based signature and credential schemes. The protocols also allow signature verifiers to dynamically choose, for each message, the amount of work it would like to perform to verify the signature. This results in a work-security tradeoff. We introduce a fifth protocol to perform variable-base variable- exponent exponentiation, which also has this feature. Our model allows the trusted resource to perform computations in its idle time. The protocols facilitate the offloading of work to the offline stage, such that the work the trusted resource performs when it has to do an exponentiation is smaller. Our protocols are unconditionally secure.     

Further exploration of antimicrobial ketodihydronicotinic acid derivatives by multiple parallel syntheses

A synthetic reexamination of a series of ketodihydronicotinic acid class antibacterial agents was undertaken in an attempt to improve their therapeutic potential. A convenient new synthesis was developed involving hetero Diels-Alder chemistry producing 74 new analogs in a multiple parallel synthetic manner and these were examined in vitro for their antimicrobial potential. Several compounds demonstrated significant broad-spectrum activity against clinically derived bacterial strains but previously known 1-(2,4-difluorophenyl)-6-(4-dimethylaminophenyl)-4-pyridone-3-carboxylic acid (7) remained the most potent compound in this class. Cross-resistance with ciprofloxacin supported a commonality of mode of action. Permiabilization of Escherichia coli cells by polymyxin B significantly enhanced potency with these agents suggesting that poor cellular uptake was primarily responsible for the disappointing activity against bacteria that some of the analogs exhibited.     

Algorithms for non-uniform size data placement on parallel disks

We study an optimization problem that arises in the context of data placement in a multimedia storage system. We are given a collection of M multimedia objects (data items) that need to be assigned to a storage system consisting of N disks d₁,d₂,…,d_N. We are also given sets U₁,U₂,…,U_M such that U_i is the set of clients seeking the ith data item. Data item i has size s_i. Each disk d_j is characterized by two parameters, namely, its storage capacity C_j which indicates the maximum total size of data items that may be assigned to it, and a load capacity L_j which indicates the maximum number of clients that it can serve. The goal is to find a placement of data items to disks and an assignment of clients to disks so as to maximize the total number of clients served, subject to the capacity constraints of the storage system.We study this data placement problem for homogeneous storage systems where all the disks are identical. We assume that all disks have a storage capacity of k and a load capacity of L. Previous work on this problem has assumed that all data items have unit size, in other words s_i=1 for all i. Even for this case, the problem is NP-hard. For the case where s_i{1,…,Δ} for some constant Δ, we develop a polynomial time approximation scheme (PTAS). This result is obtained by developing two algorithms, one that works for constant k and one that works for arbitrary k. The algorithm for arbitrary k guarantees that a solution where at least -fraction of all clients are assigned to a disk (under certain assumptions). In addition we develop an algorithm for which we can prove tight bounds when s_i{1,2}. In fact, we can show that a -fraction of all clients can be assigned (under certain natural assumptions), regardless of the input distribution.     

New quinoxaline-piperazine-oxazole conjugates: Synthesis,in vitro anticancer,in silico ADMET,and molecular docking studies

In this paper, we describe the synthesis of some new quinoxaline-piperazine-oxazole amide conjugates 6a-n from 3-chloroquinoxaline-2-carbonitrile using well-known reaction sequences. The synthesized compounds were characterized by ¹H NMR,¹³C NMR, and mass spectral analysis. The compounds were tested for their in vitro antiproliferative activity toward four different cancer cell lines such as PC-3, MCF-7, DU-145, and A-549 by MTT method. The compounds, 6c, 6h, 6i , and 6n were found to be more potent than the standard Erlotinib. In vitro tyrosine kinase EGFR inhibition studies using four potent compounds revealed that 6n has double inhibiting tendency with value IC₅₀ of 0.22 μM and 6h with value of IC₅₀ 0.27 μM compared to reference compound. Molecular docking studies of active compounds, 6c , 6h , 6i , and 6n on EGFR receptor suggested that all the compounds have more binding energies than that of Erlotinib. Furthermore, the in silico pharmacokinetic profile was accomplished for the active compounds, 6c , 6h , 6i , and 6n using SWISS/ADME and pk CSM, whereas compounds, 6h , 6i , and 6c followed Lipinski rule, Veber rule, Egan rule and Muegge rule. The remaining compound 6n did not follow Lipinski rule, Ghose rule because one common violation, that is, because of high molecular weight (MW > 350).     

Design,Synthesis, and Biological Evaluation of 1,2,4-Oxadiazole-Isoxazole Linked Quinazoline Derivatives as Anticancer Agents

Russian Journal of General Chemistry - A series of novel 1,2,4-oxadiazole-isoxazole linked quinazoline compounds is designed, synthesized and screened for anticancer activity on four human cancer...     

Entropy generation analysis of tangent hyperbolic fluid in quadratic Boussinesq approximation using spectral quasi-linearization method

Applied Mathematics and Mechanics - In many industrial applications, heat transfer and tangent hyperbolic fluid flow processes have been garnering increasing attention, owing to their immense...     

WEB-spline based mesh-free finite element analysis for the approximation of the stationary Navier–Stokes problem

The objective in this paper is to discuss the existence and the uniqueness of a weighted extended B$B$-spline (WEB-spline) based discrete solution for the stationary incompressible Navier–Stokes equations. The WEB-spline discretization is newly developed methodology which satisfies the inf–sup condition or Ladyshenskaya–Babus?ka–Brezzi (LBB) condition. The main advantage of these new elements over standard finite elements is that they use regular grids instead of irregular partitions of the domain, thus eliminating the difficult and time-consuming pre-processing step. An error estimate for this WEB-spline based discrete solution is also obtained.