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1.
We study a leader follower game with two players: a terrorist and a state where the later one installs facilities that provide support in case of a terrorist attack. While the Terrorist attacks one of the metropolitan areas to maximize his utility, the State, which acts as a leader, installs the facilities such that the metropolitan area attacked is the one that minimizes her disutility (i.e., minimizes ‘loss’). We solve the problem efficiently for one facility and we formulate it as a mathematical programming problem for a general number of facilities. We demonstrate the problem via a case study of the 20 largest metropolitan areas in the United States. 相似文献
2.
Noga Alon Oded Goldreich Johan Hstad Ren Peralta 《Random Structures and Algorithms》1992,3(3):289-304
We present three alternative simple constructions of small probability spaces on n bits for which any k bits are almost independent. The number of bits used to specify a point in the sample space is (2 + o(1)) (log log n + k/2 + log k + log 1/?), where ? is the statistical difference between the distribution induced on any k bit locations and the uniform distribution. This is asymptotically comparable to the construction recently presented by Naor and Naor (our size bound is better as long as ? < 1/(k log n)). An additional advantage of our constructions is their simplicity. 相似文献
3.
Rapid liquid chromatography-ultraviolet determination of organic acids and phenolic compounds in red wine and must 总被引:1,自引:0,他引:1
A reversed-phase liquid chromatography-ultraviolet (LC-UV) method is proposed for the rapid simultaneous analysis of the main carboxylic acids and polyphenols in must and wine. Good resolution was obtained for citric, tartaric, malic, lactic, acetic, caffeic, ellagic and gallic acids, (-)-epicatechin, quercetin and resveratrol. A novel silica-based column containing ether-linked phenyl groups, with polar end-capping and suitable for low-pH aqueous mobile phases was used and found to be superior to others tested. The method employed a mixture of 0.2% TFA in water and acetonitrile as eluents, showed linearity and precision, and was applied to samples of must and wine. 相似文献
4.
Summary Let be a circle domain in the Riemann sphere whose boundary has -finite linear measure. We show that is rigid in the sense that any conformal homeomorphism of onto any other circle domain is equal to the restriction of a Möbius transformation. Previously, Kaufman and Bishop have independently found examples of non-rigid circle, domains whose boundary is a Cantor set of (Hausdorff) dimension one.Oblatum 19-VI-1992 & 2-IV-1993Supported by NSF and Sloan Foundation 相似文献
5.
We study the nucleation of a single pore in a fluctuating lipid membrane, specifically taking into account the membrane fluctuations, as well as the shape fluctuations of the pore. For large enough pores, the nucleation free energy is well-described by shifts in the effective membrane surface tension and the pore line tension. Using our framework, we derive the stability criteria for the various pore formation regimes. In addition to the well-known large-tension regime from the classical nucleation theory of pores, we also find a low-tension regime in which the effective line and surface tensions can change sign from their bare values. The latter scenario takes place at sufficiently high temperatures, where the opening of a stable pore of finite size is entropically favorable. 相似文献
6.
Oded Schramm 《Inventiones Mathematicae》1992,107(1):543-560
Summary This paper proves that given a convex polyhedronP 3 and a smooth strictly convex bodyK 3, there is some convex polyhedronQ combinatorically equivalent toP whichmidscribes K; that is, all the edges ofQ are tangent toK. Furthermore, with some stronger smoothness conditions on K, the space of all suchQ is a six dimensional differentiable manifold.Oblatum 18-V-1991 相似文献
7.
Chakraborty D Horchler S Krätzner R Varkey SP Pinkas J Roesky HW Usón I Noltemeyer M Schmidt HG 《Inorganic chemistry》2001,40(11):2620-2624
Reaction of t-BuP(O)(OSiMe(3))(OH) with Me(3)Al leads to the formation of [Me(2)Al(mu-O)(2)P(OSiMe(3))(t-Bu)](2) (1) whereas Me(2)AlCl reacts with Ph(2)P(O)(OH) to yield [(Cl)(Me)Al(mu-O)(2)PPh(2)](2) (2). These compounds represent the first examples of functionalized dimeric four-ring type aluminophosphonate systems. The double four-ring type gallophosphonate, namely, [t-BuPO(3)GaMe](4), reacts with n-Bu(4)NHF(2) under ambient conditions, resulting in the formation of a monomeric gallophosphonate [n-Bu(4)N][MeGa[t-BuPO(2)(OH)](3)] (3). These derivatives have been adequately characterized using various spectroscopic techniques and X-ray diffraction studies. 相似文献
8.
Nir Sukenik Francesco Tassinari Shira Yochelis Oded Millo Lech Tomasz Baczewski Yossi Paltiel 《Molecules (Basel, Switzerland)》2020,25(24)
The spin–spin interactions between chiral molecules and ferromagnetic metals were found to be strongly affected by the chiral induced spin selectivity effect. Previous works unraveled two complementary phenomena: magnetization reorientation of ferromagnetic thin film upon adsorption of chiral molecules and different interaction rate of opposite enantiomers with a magnetic substrate. These phenomena were all observed when the easy axis of the ferromagnet was out of plane. In this work, the effects of the ferromagnetic easy axis direction, on both the chiral molecular monolayer tilt angle and the magnetization reorientation of the magnetic substrate, are studied using magnetic force microscopy. We have also studied the effect of an applied external magnetic field during the adsorption process. Our results show a clear correlation between the ferromagnetic layer easy axis direction and the tilt angle of the bonded molecules. This tilt angle was found to be larger for an in plane easy axis as compared to an out of plane easy axis. Adsorption under external magnetic field shows that magnetization reorientation occurs also after the adsorption event. These findings show that the interaction between chiral molecules and ferromagnetic layers stabilizes the magnetic reorientation, even after the adsorption, and strongly depends on the anisotropy of the magnetic substrate. This unique behavior is important for developing enantiomer separation techniques using magnetic substrates. 相似文献
9.
A non-localizing pulse sequence to quantify the total amount of N-acetylaspartate (NAA) in the whole brain (WBNAA) was introduced recently [Magn. Reson. Med. 40, 684–689 (1998)]. However, it is known that regional magnetic field inhomogeneities, ΔB0s, arising from susceptibility differences at tissue interfaces, shift and broaden local resonances to outside the integration window, leading to an underestimation of the true amount of NAA in the entire brain. To quantify the upper limit of this loss, the whole-head proton MR spectrum (1H-MRS) of the water was integrated over the same frequency width as the NAA. The ratio of this area/total-water-line was 75 ± 5% in 5 volunteers. The procedure was repeated with the brain-only water peak, obtained by summing signals only from voxels within that organ from a three-dimensional chemical-shift-imaging (3D CSI) set. It indicated that <10% of the water signal loss occurred in the brain. Therefore, by analogy, WBNAA accounts for >90% of that metabolite. 相似文献
10.
The existence of sparse pseudorandom distributions is proved. These are probability distributions concentrated in a very small set of strings, yet it is infeasible for any polynomial-time algorithm to distinguish between truly random coins and coins selected according to these distributions. It is shown that such distributions can be generated by (nonpolynomial) probabilistic algorithms, while probabilistic polynomial-time algorithms cannot even approximate all the pseudorandom distributions. Moreover, we show the existence of evasive pseudorandom distributions which are not only sparse, but also have the property that no polynomial-time algorithm may find an element in their support, except for a negligible probability. All these results are proved independently of any intractability assumption. 相似文献