53,594 research outputs found
Set Membership with Non-Adaptive Bit Probes
No full textWe consider the non-adaptive bit-probe complexity of the set membership problem, where a set S of size at most n from a universe of size m is to be represented as a short bit vector in order to answer membership queries of the form "Is x in S?" by non-adaptively probing the bit vector at t places. Let s_N(m,n,t) be the minimum number of bits of storage needed for such a scheme. In this work, we show existence of non-adaptive and adaptive schemes for a range of t that improves an upper bound of Buhrman, Miltersen, Radhakrishnan and Srinivasan (2002) on s_N(m,n,t). For three non-adaptive probes, we improve the previous best lower bound on s_N(m,n,3) by Alon and Feige (2009)
Improved Explicit Data Structures in the Bit-Probe Model Using Error-Correcting Codes
No full textWe consider the bit-probe complexity of the set membership problem: represent an n-element subset S of an m-element universe as a succinct bit vector so that membership queries of the form "Is x ∈ S" can be answered using at most t probes into the bit vector. Let s(m,n,t) (resp. s_N(m,n,t)) denote the minimum number of bits of storage needed when the probes are adaptive (resp. non-adaptive). Lewenstein, Munro, Nicholson, and Raman (ESA 2014) obtain fully-explicit schemes that show that
s(m,n,t) = ((2^t-1)m^{1/(t - min{2⌊log n⌋, n-3/2})}) for n ≥ 2,t ≥ ⌊log n⌋+1 .
In this work, we improve this bound when the probes are allowed to be superlinear in n, i.e., when t ≥ Ω(nlog n), n ≥ 2, we design fully-explicit schemes that show that
s(m,n,t) = ((2^t-1)m^{1/(t-{n-1}/{2^{t/(2(n-1))}})}),
asymptotically (in the exponent of m) close to the non-explicit upper bound on s(m,n,t) derived by Radhakrishan, Shah, and Shannigrahi (ESA 2010), for constant n.
In the non-adaptive setting, it was shown by Garg and Radhakrishnan (STACS 2017) that for a large constant n₀, for n ≥ n₀, s_N(m,n,3) ≥ √{mn}. We improve this result by showing that the same lower bound holds even for storing sets of size 2, i.e., s_N(m,2,3) ≥ Ω(√m)
Set Membership with Two Classical and Quantum Bit Probes
No full textWe study the classical and quantum bit-probe versions of the static set membership problem : Given a subset, S (|S| ≤ n) of a universe, (|| = m ≫ n), represent it as a binary string in memory so that the query "Is x in S?" (x ∈ ) can be answered by making at most t probes into the string. Let s_{A}(m,n,t) denote the minimum length of the bit string in any scheme that solves this static set membership problem. We show that for n ≥ 4
s_A(m,n,t = 2) =
(m^{1-1/(n-1)}) (if n = 0 (mod 3));
(m^{1-1/n}) (if n = 1,2 (mod 3));
(m^{6/7}) (if n = 8,9).
These bounds are shown using a common scheme that is based on a graph-theoretic observation on orienting the edges of a graph of high girth. For all n ≥ 4, these bounds substantially improve on the previous best bounds known for this problem, some of which required elaborate constructions [Mirza Galib Anwarul Husain Baig and Deepanjan Kesh, 2020]. Our schemes are explicit. A lower bound of the form s_A(m,n,2) = Ω(m^{1-1/⌊{n/4}⌋}) was known for this problem. We show an improved lower bound of s_A(m,n,2) = Ω(m^{1-2/(n+3)}); this bound was previously known only for n = 3,5 [Mirza Galib Anwarul Husain Baig and Deepanjan Kesh, 2020; Mirza Galib Anwarul Husain Baig et al., 2019; Mirza Galib Anwarul Husain Baig and Deepanjan Kesh, 2018; Mirza Galib Anwarul Husain Baig et al., 2019; Mirza Galib Anwarul Husain Baig and Deepanjan Kesh, 2020].
We consider the quantum version of the problem, where access to the bit-string b ∈ {0,1}^s is provided in the form of a quantum oracle that performs the transformation _b: |i⟩ ↦ (-1)^{b_i} |i⟩. Let s_Q(m,n,2) denote the minimum length of the bit string that solves the above set membership problem in the quantum model (with adaptive queries but no error). We show that for all n ≤ m^{1/8}, we have s_{QA}(m,n,2) = (m^{7/8}). This upper bound makes crucial use of Nash-William’s theorem [Diestel, 2005] for decomposing a graph into forests. This result is significant because, prior to this work, it was not known if quantum schemes yield any advantage over classical schemes. We also consider schemes that make a small number of quantum non-adaptive probes. In particular, we show that the space required in this case, s_{QN}(m,n = 2,t = 2) = O(√m) and s_{QN}(m,n = 2,t = 3) = O(m^{1/3}); in contrast, it is known that two non-adaptive classical probes yield no savings. Our quantum schemes are simple and use only the fact that the XOR of two bits of memory can be computed using just one quantum query to the oracle
Acoustic radiation due to scattering of T-S wave by the mean-flow distortion induced by steady local suction
No full textSubstantial sound waves can be generated by boundary-layer instability modes when the latter are scattered by a rapid mean-flow distortion. This is a rather generic mechanism and operates when an oncoming T-S wave is scattered by a steady local suction slot. This paper focuses on this problem by extending a recently developed Local Scattering Theory (Wu & Dong, J. Fluid Mech. submitted), where a so-called transmission coefficient, defined as the ratio of the T-S wave amplitude downstream of the scatter to that upstream, is introduced to characterize the effect of a local scatter on boundary-layer instability and transition. As in the earlier work, the mathematical formulation is based on triple-deck formulism, but in order to accommodate the acoustic far field, which was not considered in the paper mentioned, the unsteady terms in the upper deck, which play a leading-order role in radiation, are retained, and the influence of the radiated sound on the near-wall perturbation is included. The upper deck equation for the pressure is the Helmholtz equation rather than the Laplace equation. This leads to a modified pressure-displacement relation, which is coupled with the linearized boundary-layer equations in the lower deck. Discretization of the whole system formulates a generalized eigenvalue problem, which is solved numerically. It is found that suction suppresses oncoming T-S waves, and this effect increases with the suction velocity and the slot width. The directivity is ndependent of the flow parameters only when the Mach number is low. The intensity of the radiated sound in general increases with the frequency, the suction velocity and the width of the suction slot. Interestingly, for O(1) suction velocities, the radiated sound is very weak, indicating that the gain of stabilizing effect does not cause aeroacoustic penalty
Sluggishness in the phase transformation in solid C<SUB>70</SUB>
No full textIn an earlier paper [G. Ghosh, V.S. Sastry, C.S. Sundar, T.S. Radhakrishnan, Solid State Commun. 105 (1998) 247] we have reported that at low temperatures the ideal hcp (c/a~1.63) solid C70transforms to a monoclinic structure, in a single step. The transition is broadened over a temperature interval of about 100 K, for a cooling rate ~0.0033 K/min, indicating the coexistence of two phases in this temperature range. The width of broadening is cooling-rate dependent [G. Ghosh, V.S. Sastry, C.S. Sundar, S. Sengupta, T.S. Radhakrishnan, Phys. Rev. B 58 (1998) 14 094]. We have observed experimentally that the transition from hcp to monoclinic in the solid C70 is sluggish which may cause the broadening in the transition. Our mean-field calculation in this paper, using the Landau free energy functional, indicates that the sluggishness originates from the growing interface due to the elastic strain between the two phases
Measuring industry-science links through inventor-author relations: A profiling method
No full textIn this pilot study we examine the performance of text-based profiling in recovering a set of validated inventor-author links. In a first step we match patents and publications solely based on their similarity in content. Next, we compare inventor and author names on the highest ranked matches for the occurrence of name matches. Finally, we compare these candidate matches with the names listed in a validated set of inventor-author names. Our text-based profile methodology performs significantly better than a random matching of patents and publications, suggesting that text-based profiling is a valuable complementary tool to the name searches used in previous studies.innovation; industry-science links; text-based profiling;
The maternal immune system during pregnancy and its influence on fetal development
No full textThe maternal immune system plays a critical role in the establishment, maintenance, and completion of a healthy pregnancy. However, the specific mechanisms utilized to achieve these goals are not well understood. Various cells and molecules of the immune system are key players in the development and function of the placenta and the fetus. Effector cells of the immune system act to promote and yet limit placental development. The T helper 1 (Th1)/T helper 2 (Th2) immune shift during pregnancy is well established. A fine balance between proinflammatory and anti-inflammatory influences is required. We herein review the evidence regarding maternal tolerance of fetal tissues and the underlying cell-mediated immune and humoral (hormones and cytokines) mechanisms. We also note the many unanswered questions in our understanding of these mechanisms. In addition, we summarize the clinical manifestations of an altered maternal immune system during pregnancy related to susceptibility to common viral, bacterial, and parasitic infections, as well as to autoimmune diseases.Peer reviewe
S-heterocyclic carbene with a disilane backbone
No full textPT: J; CR: AKASAKA T, 1999, ORG LETT, V1, P1509 AKASAKA T, 2000, J AM CHEM SOC, V122, P7134 ALCARAZO M, 2004, J AM CHEM SOC, V126, P13242 ALDER RW, 1999, CHEM COMMUN 0207, P241 ARDUENGO AJ, 1991, J AM CHEM SOC, V113, P361 ARDUENGO AJ, 1995, J AM CHEM SOC, V117, P11027 BAZINET P, 2003, J AM CHEM SOC, V123, P13314 BECKE AD, 1988, PHYS REV A, V38, P30989 BECKE AD, 1993, J CHEM PHYS, V98, P5648 BOURISSOU D, 2000, CHEM REV, V100, P39 DESPAGNETAYOUB E, 2004, J AM CHEM SOC, V126, P10198 DESPAGNETAYOUB E, 2005, ORGANOMETALLICS, V24, P338 ENDERS D, 2001, J ORGANOMET CHEM, V617 FABIAN J, 2000, J ORG CHEM, V65, P8940 FEKETE A, 2002, J ORGANOMET CHEM, V643, P278 FRANCL MM, 1982, J CHEM PHYS, V77, P3654 GRAHAM DC, 2005, J PHYS ORG CHEM, V18, P298 HAHN FE, 2000, ANGEW CHEM INT EDIT, V39, P541 HAHN FE, 2000, ANGEW CHEM, V112, P551 HERRMANN WA, 2002, ANGEW CHEM INT EDIT, V41, P1290 HERRMANN WA, 2002, ANGEW CHEM, V114, P1342 HILLIER AC, 2002, J ORGANOMET CHEM, V653, P69 HIRSCH A, 1993, CHEM BER, V126, P1061 HOZ T, 1993, CHEM SULFUR CONTAINI, P1 ISHITSUKA MO, 2004, TETRAHEDRON LETT, V45, P6321 JAFARPOUR L, 2001, ADV ORGANOMET CHEM, V46, P181 KRAHULIC KE, 2005, J AM CHEM SOC, V127, P4142 KYUSHIN S, 1994, CHEM LETT, P997 KYUSHIN S, 1996, J ORGANOMET CHEM, V521, P413 KYUSHIN S, 2000, CHEM LETT 0505, P494 LEE C, 1988, PHYS REV B, V37, P785 LIU MTH, 2003, J ORG CHEM, V68, P7471 MARTIN D, 2005, ANGEW CHEM INT EDIT, V44, P1700 MARTIN D, 2005, ANGEW CHEM, V117, P1728 MATSUMOTO H, 2000, J ORGANOMET CHEM, V611, P52 MOSS RA, 1980, ACCOUNTS CHEM RES, V13, P58 MOSS RA, 1988, J AM CHEM SOC, V110, P4443 OTTO M, 2004, J AM CHEM SOC, V126, P1016 PERRY MC, 2003, TETRAHEDRON-ASYMMETR, V14, P951 PIETRO WJ, 1982, J AM CHEM SOC, V104, P5039 WAKAHARA T, 2002, J AM CHEM SOC, V124, P9465 WIBERG N, 2002, CHEM-EUR J, V8, P2730 WIN WW, 1994, J ORG CHEM, V59, P5817; NR: 43; TC: 1; J9: ANGEW CHEM INT ED; PG: 4; GA: 989STSource type: Electronic(1
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
No full textIFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells
Letter from Carl Hayden to Fred S. Breen
No full textLetter from Carl T. Hayden to Fred S. Breen concerning the expenditure of $100,000 to purchase Bright Angel Trail
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