199,971 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)
Trust, family firms, and M&A quality
No full textThis paper examines the effect of trust on the quality of M&A across family and non-family firms. We find that family firms are associated with better M&A quality than non-family firms and that M&A deals involving high trust are of better quality. When we consider the association of trust, family firms and their interaction, we find that trust is the channel/mechanism through which family firms are associated with better M&A quality. Collectively, these results suggest that trust enables family firms to build long-term relationships with employees, suppliers and customers, and potentially mitigate the Type I agency problems
Bactrocera (Bactrocera) digressa Radhakrishnan, s.str.
No full textBactrocera (Bactrocera) digressa Radhakrishnan Bactrocera (Bactrocera) digressa Radhakrishnan, 1999. Rec.Zool.Surv. India, 97(4):1. Holotype ♀. India (Tamil Nadu: Salem dist., Shevroy Hills, Semmanathan) (ZSI) [not examined] Bactrocera (Daculus) yercaudiae Drew, 2002. Raffles Bull.Zool., 50(2): 346. Holotype ♂. India (Tamil Nadu: Yercaud, 15 Km from Yercaud) (BMNH) [not examined]; syn.nov. Material examined INDIA: Karnataka: 11 ♂, Bangalore, 916m, 10.vii.1989, S. Ramani; 2 ♂, same data except 11.vii.1989; 1 ♂, same data except 4.ii.1989; 2 ♂, same data except 3.vii.1988, G. Bhat; 3 ♂, Bangalore, Hessaraghatta, 916m, 14.iii.1987, G. Bhat; 3 ♂ same data except 23.i.1988; 2 ♂ same data except 9.vii.1988; 2 ♂, 1♀, Bangalore, GKVK, 4.ii.2008, David, K. J.; 1 ♂, same data except 20.i.2008; 1 ♂, same data except 8.vi.2008, Sudha, M.; 1 ♂, Gouribidanur, 29.vi.2009, Praveen; 1 ♂, Mandya, 24-30.vii.1989, Gubbaiah; 2 ♂, Tamil Nadu, Yercaud, 3.vii.1992, S. Ramani (UASB); 2 ♀, Karnataka, Gowribidanur, Kolar, 23.vii.07, Naveen Kumar (NBAII). Radhakrishnan (1999) described Bactrocera digressa based on two females collected from Salem district, Tamil Nadu. The diagnostic characters of the species are reddish brown scutum, bifid aculeus tip, absence of acrostichal and anterior supra-alar setae. Later, Drew and Raghu (2002) described Bactrocera (Daculus) yercaudiae based on males collected from Yercaud, Tamil Nadu and Bangalore which responded to cue lure. Perusal of original description of the two species showed complete congruence of characters except costal band, which was mentioned as confluent with vein R 2+ 3 in Bactrocera digressa and slightly overlapping R in B. yercaudiae. Material mentioned above which were keyed out as Bactrocera yercaudiae were examined to confirm the identity. Examination of aculeus tip of the females revealed that it has a bifid aculeus and all the characters are in concordance with that of B. digressa except for a slightly overlapping costal band which might have been overlooked by Radhakrishnan (1999) because it is very faint beyond vein R 2+3. Hence we propose B. yercaudiae as a junior synonymn of B. digressa. Since all the Asian species in subgenus Daculus are aberrant Bactrocera s.str. and true Daculus are African, B. digressa is retained in subgenus Bactrocera (Copeland et al., 2004). As per ICZN rules, Bactrocera digressa Radhakrishnan is the valid name. Three females have been reared from fruits of Alangium lamarkii collected from Yercaud, Tamil Nadu and are deposited in BMNH (Ian M. White, pers. comm.)Published as part of David, K. J. & Ramani, S., 2011, An illustrated key to fruit flies (Diptera: Tephritidae) from Peninsular India and the Andaman and Nicobar Islands, pp. 1-31 in Zootaxa 3021 on page 1
Platessa arborea C. Radhakrishnan, S. Sherly & B. Karthick 2022, sp. nov.
No full textPlatessa arborea C. Radhakrishnan, S. Sherly & B. Karthick sp. nov. (Figs 1–67, Fig. 9 represents the holotype) LM Description (Figs 1–60):—Valve elliptical with narrowly rounded apices. Raphe-sternum valve (RSV): Length: 6.5–9.5 µm, width: 3.5–4.5 µm, ratio length/width: 1.6–2.2 (n = 60). Axial area narrow and hardly discernible, visible only near center of the valve; central area nearly rectangular shape, bordered by 2–3 shorter striae frequently more widely spaced. Striae radiate throughout the valve, 22–24 in 10 µm. Raphe slightly filiform expanded proximal raphe endings. Sternum valve (SV): wide axial area, Length: 6.0–9.0 µm, width: 3.5–4.5 µm. Striae densely arranged 22–24 in 10 µm, parallel at centre, radiate towards apices. SEM Description (Figs 61–67):—Raphe-sternum valve (RSV): Externally, raphe filiform, slight curvature found near ends (Figs 61 & 63). Proximal raphe ends positioned in a broadened shallow groove, distal raphe located in the shallow groove with cone-shaped endings, and both ends slightly bend to the same side (Fig. 61). Striae mostly uniseriate; however found biseriate at 2–3 striae near apices. (Fig. 61). Areolae, apically slit-like throughout the valve, only at the center of the valve it is round-shaped towards axial area (Fig. 61). Internally, proximal raphe ends are strongly hooked, a very remarkable feature which is infrequent in other Platessa species, and its distal ends are curved on opposite sides, terminating in well-developed helictoglossae (Figs 64, 65). Striae lowered between raised virgae. Width of the interstriae is wider than the striae. Striae internally rectangular to round in shape and mostly covered with hymen (Figs 64, 65). An apparent depression is observed on the central nodule (Figs 64, 65). Sternum valve (SV), externally, axial area covered with several irregular shape depressions distributed on the surface of the valve (Fig. 62). Striae uniseriate, however, found biseriate at more than 10 striae near the valve mantle (Fig. 62). Interstriae is raised, and the width of striae is unequal (Fig. 62). Internally, axial area is flat and features are not easily visible (Fig. 66). Biseriate striae found near the mantle with hymenated areolae. Interstriae raised its width slightly more than the striae (Fig. 67). Holotype (designated here):—Slide #58/55, Sample #2878; deposited at the Diatom Collection, Agharkar Research Institute Herbarium (AHMA), Pune, India. Type locality:— INDIA, Sikkim, composite tree moss sample collected on 22 November 2019 on the way to Khecheopalri Lake, West Sikkim district (27.34829 °N, 88.19187 °E; elevation 1794 m a.s.l.) by Radhakrishnan Cheran. Etymology:—Named after the habitat (tree) on which it was found. In Latin, the tree is called an Arbor.Published as part of Sherly, Sheena, Radhakrishnan, Cheran & Karthick, Balasubramanian, 2022, Platessa arborea sp. nov. (Bacillariophyceae): A new tree moss dwelling diatom from the Eastern Himalayas, India, pp. 151-158 in Phytotaxa 552 (2) on pages 152-153, DOI: 10.11646/phytotaxa.552.2.2, http://zenodo.org/record/669098
Impact of Fractional Derivative and Brownian Motion on the Solutions of the Radhakrishnan-Kundu-Lakshmanan Equation
No full textThe fractional-stochastic Radhakrishnan-Kundu-Lakshmanan equation (FSRKLE) is considered here. To attain new hyperbolic, elliptic, rational, and trigonometric stochastic-fractional solutions, we use two various methods such as the sine-cosine and the Jacobi elliptic function methods. The solutions acquired are important in understanding some interesting physical phenomena due to the significance of the Radhakrishnan-Kundu-Lakshmanan equation in designing the propagation of solitons through an optical fiber. Furthermore, we graph some of the obtained solutions in 3D to display the influence of fractional derivative and multiplicative noise on these solutions. Finally, we show that when the order of fractional derivative decreases, the surface shrinks, while the multiplicative noise stabilizes the solutions of FSRKLE a round zero
ERp44 mediates a thiol-independent retention of formylglycine-generating enzyme in the endoplasmic reticulum
No full textMariappan M, Radhakrishnan K, Dierks T, Schmidt B, von Figura K. ERp44 mediates a thiol-independent retention of formylglycine-generating enzyme in the endoplasmic reticulum. JOURNAL OF BIOLOGICAL CHEMISTRY. 2008;283(10):6375-6383.Inside the endoplasmic reticulum (ER) formylglycine-generating enzyme (FGE) catalyzes in newly synthesized sulfatases the post-translational oxidation of a specific cysteine. Thereby formylglycine is generated, which is essential for sulfatase activity. Here we show that ERp44 interacts with FGE forming heterodimeric and, to a lesser extent, also heterotetrameric and octameric complexes, which are stabilized through disulfide bonding between cysteine 29 of ERp44 and cysteines 50 and 52 in the N-terminal region of FGE. ERp44 mediates FGE retrieval to the ER via its C-terminal RDEL signal. Increasing ERp44 levels by overexpression enhances and decreasing ERp44 levels by silencing reduces ER retention of FGE. Suppressing disulfide bonding by mutating the critical cysteines neither abrogates ERp44.FGE complex formation nor interferes with ERp44-mediated retention of FGE, indicating that noncovalent interactions between ERp44 and FGE are sufficient to mediate ER retention. The N-terminal region of FGE harboring Cys(50) and Cys(52) is dispensible for catalytic activity in vitro but required for FGE-mediated activation of sulfatases in vivo. This in vivo activity is affected neither by overexpression nor by silencing of ERp44, indicating that a further ER component interacting with the N-terminal extension of FGE is critical for sulfatase activation
An Improved Bound on the Zero-Error List-Decoding Capacity of the 4/3 Channel
No full textWe prove a new upper bound on the size of codes C 1,2,3,4
with the property that every four distinct codewords in C have a coordinate where they all differ. Specifically, we provide a self-contained proof that such codes have size at most 26n/19 + o(n), that is, rate bounded asymptotically by 6/19 ≤ 0.3158 (measured in bits). This improves the previous best upper bound of 0.3512 due to (Arikan 1994), which in turn improved the 0.375 bound that followed from general bounds for perfect hashing due to (Fredman and Komlós, 1984) and (Körner and Marton, 1988). Finally, using a combination of our approach with a simple idea which exploits powerful bounds on the minimum distance of codes in the Hamming space, we further improve the upper bound to 0.31477
Myopia: part 1
No full textIn the first of a three-part series looking at myopia, Dr Peter Allen and Dr Hema Radhakrishnan describe the reasons why for some people emmetropisation fails to occur, leaving them myopic
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No full textNot AvailableBilateral eyestalk ablation can accelerate somatic and reproductive growth in spiny lobsters (Quakenbush and Hernkind 1981, Radhakrishnan and Vijayakumaran 1984a, b). In studies of the spiny lobsters Panulirus homarus and P. ornatus, we obseerved interesting changes in morphology and in feeding and reproductive behavior after eyestalk ablation.Not Availabl
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