3,353 research outputs found
[Doc Wildman and John Sutton in Martin TT]
No full textImage of Doc Wildman and Lt. John Sutton seated in a Martin TT floatplane
[John Sutton and His Crew, with Martin TT]
No full textImage of John Sutton (right) standing on a seaplane transport cart in the water while his Martin TT is worked on in the background
Isomorphisms in co-TT graphs
No full text2019 Spring.Includes bibliographical references.A threshold tolerance graph is a graph where each vertex v is assigned a weight wv and a tolerance tv, and there is an edge between two vertices vx and vy if and only if wx + wy ≥ min(tx,ty). A co-TT graph is the complement of a threshold tolerance graph. Recognition of these graphs can be done in O(n2) time; however no polynomial-time algorithm to identify isomorphisms between pairs of TT or co-TT graphs was previously known. We give an algorithm to identify these isomorphisms, which takes O(n2) time
tt*-geometry and pluriharmonic maps
No full textInternational audienceIn this paper we use the real differential geometric definition of a metric (an unimodular oriented metric) tt*-bundle of Cortés and the author to define a map from the space of metric (unimodular oriented metric) tt*-bundles of rank r over a complex manifold M to the space of pluriharmonic maps from M to (respectively ), where (p,q) is the signature of the metric. In the sequel the image of the map is characterized. It follows, that in signature (r,0) the image of is the whole space of pluriharmonic maps. This generalizes a result of Dubrovin
performance of the low-rank TT-SVD for large dense tensors on modern multicore CPUs
No full textThere are several factorizations of multidimensional tensors into lower-dimensional components, known as ``tensor networks."" We consider the popular ``tensor-train"" (TT) format and ask, How efficiently can we compute a low-rank approximation from a full tensor on current multicore CPUs? Compared to sparse and dense linear algebra, kernel libraries for multilinear algebra are rare and typically not as well optimized. Linear algebra libraries like BLAS and LAPACK may provide the required operations in principle but often at the cost of additional data movements for rearranging memory layouts. Furthermore, these libraries are typically optimized for the compute-bound case (e.g., square matrix operations), whereas low-rank tensor decompositions lead to memory bandwidth limited operations. We propose a ``TT singular value decomposition"" (TT-SVD) algorithm based on two building blocks: a ``Q-less tall-skinny QR"" factorization and a fused tall-skinny matrix-matrix multiplication and reshape operation. We analyze the performance of the resulting TT-SVD algorithm using the roofline performance model. In addition, we present performance results for different algorithmic variants for shared-memory as well as distributed-memory architectures. Our experiments show that commonly used TT-SVD implementations suffer severe performance penalties. We conclude that a dedicated library for tensor factorization kernels would benefit the community: Computing a low-rank approximation can be as cheap as reading the data twice from main memory. As a consequence, an implementation that achieves realistic performance will move the limit at which one has to resort to randomized methods that only process part of the data.Numerical Analysi
"_Pst-tt!", circa 1962
No full textA dark figure marked "Merchants" opens a door labeled "Back Door Deals". Written on recto: "_Pst-tt!".Crim
Microbiology Topics. ABOUT THE AUTHOR Measurement of Microbial Cells by Optical Density
No full text"Microbiology Topics" discusses various topics in microbiology of practical use in validation and compliance. We intend this column to be a useful resource for daily work applications. Reader comments, questions, and suggestions are needed to help us fulfill our objective for this column. Please send your comments and suggestions to column coordinator Scott Sutton at scott. [email protected] or journal coordinating editor Susan Haigney at [email protected]. KEY POINTS The following key points are discussed: Quality control (QC) microbiology tests require controlled levels of inocula and require fresh preparations of cells for those inocula The concentration of cells in a suspension can be estimated by optical density, but this must be confirmed by plate count The optical density readings against cell mass are specific to the microorganism species The qualification of these readings must be confirmed after major maintenance to the bench top spectrophotometer (e.g., after replacement of the bulb). There are, of course, two problems with these instructions. The first is that the technician is instructed to use an inoculum of about 10 8 microorganisms per milliliter and then instructed to determine this by plate count. Colony forming units (CFU) and cells (micro-organisms and spores) are different measures. This will inevitably lead to difficulties as the unfortunate lab worker cannot guarantee the number of cells in the suspension, only the number of CFU found. However, we can accept the scientific inaccuracy, as the numbers will generally work out. The more serious problem is the instruction to use the plate count CFU for determination of the inoculum for the test, and that the suspension shall be used immediately. This quite frankly cannot be done. If you use the suspension immediately, the plate counts are unavailable; if you use the plate counts to set the inoculum, then the suspension is at least a day old. DETERMINATION OF INOCULUM FOR THE AET Contrast these instructions with those in the United States Pharmacopeia (USP) (2) for the same exercise: Scott Sutton are needed to help us fulfill our objective fo fo for this column. Please send your comments an an and d d su u ugg gg gges es etions to column coordinator Scott Su Su Sutt tt tton n n at sc sc scot ot ott. t. t. [email protected] or journal co co coor o o dina a nating e e editor Susan Haigney at shaigney@ y@ [email protected]. KEY POINTS suspending fluid … Add sufficient suspend fluid to reduce the microbial count to about micro-organisms per milliliter…Remove imm ately a suitable sample from each suspension d d de d termine the number of colony-forming u per milliliter in each suspension by plate coun membrane filtration (2.6.12). This value se KEY POINTS The following key points are discuss sed ed: Quality control (QC) microbiolog gy test sts s re equ quire controlled levels of inocula and nd r re equi ire f fresh sh preparations of cells for those inocula The co o onc ncen en ntr tr trat at atio io ion n n of cells in n a a su uspen nsi sion o can be es s sti i imated b b by y y op op opti ti tical dens nsity, y, b but ut this s mu must s be membrane filtration (2.6.12). This value se to determine the inoculum and the baselin use in the test. The suspensions shall be u immediately." There are, of course, two problems with these t t tion n ns. s. s. T T The he he f f fir ir irst st i is s s th th hat at t t th h he t t tec e echnicia an is is i ins nstr truc u te an an an ino no noculum of a a abo out 10 0 0 8 8 8 m m mic croorg gan nisms s pe per m c co conf f fir rmed by p p plate te te c c cou o o nt t Th h he op p ptical den n nsit t ty r re rea adin ings gs a agai inst st cel e l m mass a are r s s sp s ec ec ec e ifi i ic to th h h he e e e m m mi m croo o o org gan an anis is sm specie ie es Th Th Th he q qu l l alif if ifi i ication of the h h se readings mu t t st be confirmed e e e a a a after m m m maj j j jor o o mai ai aint t ten e e ance ce ce t t to o o the e e be b b nc c ch h h t t top sp sp sp spec ec e ect t tropho ho ho hoto to to tom m meter r (e (e (e.g g g., aft fter er er r repla ace ement nt nt of the bulb) a a and d d th th then n n i i instru u ucte e ed to o o d d deter erm mine e thi his s by by plat C C Colony f f fo o orm m ming un n nits ( ( (CF C CFU) U) a and nd ce ells s ( (mi mic cro-or an an and d d d sp p por r res es es es) ) ) ) are d d dif f ffer er er ere e en e t measu ur u es es es. T This w w wil ill l l in l l lead d d d t t t to o o di di di dif fficulties as t t the unfortun t t ate lab wo k k rke guar r r ran a a a tee th th th he e e e numb mb mb ber of f f f ce ce ce cell ll lls s in t t the he he s s sus u u pens ns nsi i i the e e nu nu nu numb m m m er o o of CFU U U foun n n nd d. d. d H H Ho ow o ev ver er r, , w w we can n n a a ac scientific inaccuracy as the numbers will genera of the bulb) ) ). DE DE DE DETE TE TE TERM RM RM RMIN IN IN INAT AT AT ATIO IO IO ION N N N OF OF OF OF I I INO NO NOCU CU CULU LU LUM M M FO FO FOR R R scientific inaccuracy, y as the numbers will g genera ou ou ou out. t t t Th Th Th The e e e mo mo mo more re re re s s ser er er erio io io ious us us us p p p pro r ro robl bl bl blem em em i i is s s th th the e e in in inst st stru ru ruct ct ctio o th th th the e e e pl pl pl plat at at a e e e e co co co coun un un unt t t t CF CF CF CFU U U U fo fo fo for r r r de de de dete te te t rm rm rmin in inat at atio io ion n n of of of t t the he he i i in
Search for tt¯ H/ A→ tt¯ tt¯ production in the multilepton final state in proton–proton collisions at √s = 13 TeV with the ATLAS detector
No full textA search for a new heavy scalar or pseudo-scalar Higgs boson (H/A) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks (H/A → tt¯) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb −1 of proton–proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the tt¯ H/ A production cross-section times the branching ratio of H/A → tt¯ range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar H or the pseudo-scalar A, contributes to the tt¯ tt¯ final state, values of tan β below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to tan β below 1.6 or 0.6 when both particles are considered. [Figure not available: see fulltext.] © 2023, The Author(s)
Search for tt ̄H/A→tt ̄tt ̄ production in proton–proton collisions at s=13 TeV with the ATLAS detector
No full textA search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair (tt ̄H/A), and with the H/A decaying into a tt ̄ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139fb-1. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the tt ̄+jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the tt ̄H/A→tt ̄tt ̄ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the H and A contribute to the tt ̄tt ̄ cross-section, tanβ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a tt ̄ pair
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TT&C SYSTEM FOR NASDA NEW GROUND NETWORK
No full textInternational Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, NevadaIn response to a NASDA decision to upgrade their satellite ground network (GN) to provide worldwide coverage as well as interoperability with other agencies, MELCO has assembled remote ground stations that include the L-3 Communications Telemetry & Instrumentation (L-3 T&I) NETstar 20001 TT&C system. Software developed by Mitsubishi Electric Corporation (MELCO) controls a variety of COTS products in the remote stations, including the L-3 T&I system. L-3 T&I’s TT&C system provides modem services, high accuracy ranging, Doppler compensation, command verification, and CCSDS protocol processing for a wide range of LEO/MEO/GEO satellites.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection
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