102 research outputs found
A Sharp Concentration Inequality With Applications
No full textWe present a new general concentration-of-measure inequality and illustrate its power by applications in random combinatorics. The results find direct applications in some problems of learning theory. The work of the second author was supported by DGES grant PB96-0300 1 Introduction The phenomenon of measure concentration has recently received distinguished attention due to its much better understanding and its spectacular power and simplicity in applications. The basic methods for proving concentration inequalities have been (1) martingale methods---see McDiarmid [22], [23] for excellent surveys; (2) information-theoretic methods, see Alhswede, G'acs, and Korner [1], Marton [17], [18],[19], Dembo [5] and Massart [21]; (3) Talagrand's induction method [27],[25],[26], which led to a large variety of powerful new inequalities. Recently, a new proof technique emerged based on logarithmic Sobolev inequalities, see Ledoux [14],[13]. The method has been shown to provide the sharpest ine..
Pichia anomala and Candida oleophila in Biocontrol of Postharvest Diseases of Fruits: 20 Years of Fundamental and Practical Research
No full textModelling Impact Damage on Aircraft Structures (MIDAS): Predicting impact damage on (composite) aircraft based on maintenance data of (metal) aircraft
No full textIn this thesis, a methodology is presented to predict impact damage on next-generation (composite) aircraft based on maintenance data of in-service (metal) aircraft. To achieve this conversion, an analytical model is developed to Model Impact Damage on Aircraft Structures (MIDAS) for composite (-C ) and metal (-M ) aircraft. The model characterizes impact threats based on damage dimensions in two steps. First, for a given specific threat an impact event is approximated, and the corresponding damage (i.e. the permanent dent) is estimated. Second, the analytical model is reverse engineered to deduce the impact threat characteristics from the permanent damage. MIDAS-M implements a new transition region between the local and global deformation modes based on penetration limits, while composite variant (MIDAS-C) provides a novel approach for the permanent indentation in the post fiber breakage region.Aerospace Engineerin
A multi-scale computational scheme for anisotropic hydro-mechanical couplings in saturated heterogeneous porous media
No full textThis contribution discusses a coupled two-scale framework for hydro-mechanical problems in saturated heterogeneous porous geomaterials. The heterogeneous nature of such materials can lead to an anisotropy of the hydro-mechanical couplings and non-linear effects. Based on an assumed model of the mesostructure, the average macroscopic hydro-mechanical behaviour is extracted by means of a computational homogenisation procedure in a monolithic way. The ingredients needed to upscale the hydro-mechanical couplings are outlined. The two-scale simulation results are compared with direct numerical simulation for the consolidation of a particle-matrix porous material.Structural EngineeringCivil Engineering and Geoscience
Image_2_Genome-Wide Identification and Expression Analysis of Cutinase Gene Family in Rhizoctonia cerealis and Functional Study of an Active Cutinase RcCUT1 in the Fungal–Wheat Interaction.TIF
No full textWheat (Triticum aestivum L.) is a staple food of more than 50% of global population. Rhizoctonia cerealis is the causal agent of sharp eyespot, a devastating disease of cereal crops including wheat. Cutinases produced by fungal pathogens play important roles in host-pathogen compatible interactions, but little is known about cutinases in R. cerealis. In this study, we identified a total of six cutinase encoding genes from R. cerealis genome, designated as RcCUT1–RcCUT6, analyzed their expression patterns during the infection, and determined virulence role for RcCUT1. All the proteins, RcCUT1–RcCUT6, contain a highly conserved GYSKG motif and another conserved C-x(3)-D-x(2)-C-x(2)-[GS]-[GSD]-x(4)-[AP]-H motif in the carbohydrate esterase 5 domain. The RcCUT1, RcCUT2, RcCUT4, and RcCUT5 are predicted to be secreted proteins containing four cysteine residues. These six cutinase genes had different expression patterns during the fungal infection process to wheat, among which RcCUT1 was highly expressed across all the infection time points but RcCUT6 was not expressed at all and the others were expressed only at certain time points. Further, RcCUT1 was heterologously expressed in Escherichia coli to obtain a purified protein. The purified RcCUT1 was shown to possess the cutinase activity and be able to induce necrosis, H2O2 accumulation, and expression of defense-related genes when infiltrated into wheat and Nicotiana benthamiana leaves. In contrast, RcCUT1 protein with serine mutation at the first motif had no cutinase activity, consequently lost the ability to induce necrosis. Noticeably, application of the purified RcCUT1 with R. cerealis led to significantly higher levels of the disease in wheat leaves than application of the fungus alone. These results strongly suggest that RcCUT1 serves as a virulence factor for the fungus. This is the first investigation of the cutinase genes in R. cerealis and the findings provide an important insight into pathogenesis mechanisms of R. cerealis on wheat.</p
Algebraic intersection in regular polygons
No full textWe study the function \mbox{KVol} : (X,ω)\mapsto \mbox{Vol} (X,ω) \sup_{α,β} \frac{\mbox{Int} (α,β)}{l_g (α) l_g (β)}
defined on the moduli spaces of translation surfaces. More precisely, let be the Teichmüller discs of the original Veech surface arising from right-angled triangle with angles by the unfolding construction for . For and any , we establish the (sharp) bounds \frac{n}{2} \cot \fracπ{n} \leq \mbox{KVol}(X,ω) \leq \frac{n}{2} \cot \fracπ{n} \cdot \frac1{\sin \frac{2π}{n}}.
The lower bound is uniquely realized at .New version with the first author added and completely different methods. We focus on the case, the case is dealt with in a forthcoming paper by the first author. 30pages, 15 figure
Algebraic intersection in regular polygons
No full textNew version with the first author added and completely different methods. We focus on the case, the case is dealt with in a forthcoming paper by the first author. 30pages, 15 figuresWe study the function \mbox{KVol} : (X,\omega)\mapsto \mbox{Vol} (X,\omega) \sup_{\alpha,\beta} \frac{\mbox{Int} (\alpha,\beta)}{l_g (\alpha) l_g (\beta)} defined on the moduli spaces of translation surfaces. More precisely, let be the Teichm\"uller discs of the original Veech surface arising from right-angled triangle with angles by the unfolding construction for . For and any , we establish the (sharp) bounds \frac{n}{2} \cot \frac{\pi}{n} \leq \mbox{KVol}(X,\omega) \leq \frac{n}{2} \cot \frac{\pi}{n} \cdot \frac1{\sin \frac{2\pi}{n}}. The lower bound is uniquely realized at
Testing the evolutionary link between submillimetre galaxies and quasars: CO observations of QSOs at z~2
No full textWe have used the IRAM Plateau de Bure millimetre interferometer and the UKIRT 1–5 μm Imager Spectrometer (UIST) to test the connection between the major phases of spheroid growth and nuclear accretion by mapping CO emission in nine submillimetre-detected QSOs at z= 1.7–2.6 with black hole (BH) masses derived from near-infrared spectroscopy. When combined with one QSO obtained from the literature, we present sensitive CO(3–2) or CO(2–1) observations of 10 submillimetre-detected QSOs selected at the epoch of peak activity in both QSOs and submillimetre (submm) galaxies (SMGs). CO is detected in 5/6 very optically luminous (MB∼−28) submm-detected QSOs with BH masses MBH≃ 109–1010 M⊙, confirming the presence of large gas reservoirs of Mgas≃ 3.4 × 1010 M⊙. Our BH masses and dynamical mass constraints on the host spheroids suggest, at face value, that these optically luminous QSOs at z= 2 lie about an order of magnitude above the local BH–spheroid relation, MBH/Msph, although this result is dependent on the size and inclination of the CO-emitting region. However, we find that their BH masses are ∼30 times too large and their surface density is ∼300 times too small to be related to typical SMGs in an evolutionary sequence. Conversely, we measure weaker CO emission in four fainter (MB∼−25) submm-detected QSOs with properties, BH masses (MBH≃ 5 × 108 M⊙), and surface densities similar to SMGs. These QSOs appear to lie near the local MBH/Msph relation, making them plausible ‘transition objects’ in the proposed evolutionary sequence linking QSOs to the formation of massive young galaxies and BHs at high redshift. We show that SMGs have a higher incidence of bimodal CO line profiles than seen in our QSO sample, which we interpret as an effect of their relative inclinations, with the QSOs seen more face-on. Finally, we find that the gas masses of the four fainter submm-detected QSOs imply that their star formation episodes could be sustained for ∼10 Myr, and are consistent with representing a phase in the formation of massive galaxies which overlaps a preceding SMG starburst phase, before subsequently evolving into a population of present-day massive ellipticals
Deducing the physical characteristics of an impactor from the resultant damage on aircraft structures
No full textThis paper proposes an analytical model that uses historical damage dimension data to deduce physical impactor characteristics (size and energy) that has caused a certain resulting damage. Maintenance tasks occur in operations due to impact, however the source of the damage caused in the event remains in most cases unknown. Consequently, by inferring what has caused a certain type of damage from the distribution of the damage type and severity relative to impactor types, maintainers can be better prepared in terms of what to expect from a given impactor source. The developed model introduces a novel transition deformation region between the local deformation and the global plate deflection, allowing for fast and accurate predictions of the impact event. Using the known aluminium structural properties and damage dimensions, the damage data is converted into impactor data. The model is applied in a case study using 120 fuselage dent damages dimensions (length, width, and depth) from a Boeing 777 fleet. The results show that the model deduces impactor characteristics for 94% of the considered damages, ranging up to 240 J and 110 mm for impactor energy and radius respectively.Air Transport & OperationsAerospace Structures & Computational Mechanic
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