Pair Threshold Research Articles

Online Algorithms for the Interval Scheduling Problem in the Cloud: Affinity Pair Threshold Based Approaches

Online Algorithms for the Interval Scheduling Problem in the Cloud: Affinity Pair Threshold Based Approaches

Ion Pair Supramolecular Structure Identified by ATR-FTIR Spectroscopy and Simulations in Explicit Solvent*.

The present work uses ATR-FTIR spectroscopy assisted by simulations in explicit solvent and frequency calculations to investigate the supramolecular structure of carboxylate alkali-metal ion pairs in aqueous solutions. ATR-FTIR spectra in the 0.25-4.0 M concentration range displayed cation-specific behaviors, which enabled the measurement of the appearance concentration thresholds of contact ion pairs between 1.9 and 2.6 M depending on the cation. Conformational explorations performed using a non-local optimization method associated to a polarizable force-field (AMOEBA), followed by high quantum chemistry level (RI-B97-D3/dhf-TZVPP) optimizations, mode-dependent scaled harmonic frequency calculations and electron density analyses, were used to identify the main supramolecular structures contributing to the experimental spectra. A thorough analysis enables us to reveal the mechanisms responsible for the spectroscopic sensitivity of the carboxylate group and the respective role played by the cation and the water molecules, highlighting the necessity of combining advanced experimental and theoretical techniques to provide a fair and accurate description of ion pairing.

On optimal thresholds for pairs trading in a one-dimensional diffusion model

We study the static maximization of long-term averaged profit, when optimal preset thresholds are determined to describe a pairs trading strategy in a general one-dimensional ergodic diffusion model of a stochastic spread process. An explicit formula for the expected value of a certain first passage time is given, which is used to derive a simple equation for determining the optimal thresholds. Asymptotic arbitrage in the long run of the threshold strategy is observed. doi:10.1017/S1446181121000298

Virtual corrections to gg \u2192 ZH in the high-energy and large-mt limits

We compute the next-to-leading order virtual corrections to the partonic cross-section of the process gg → ZH, in the high-energy and large-mt limits. We use Padé approximants to increase the radius of convergence of the high-energy expansion in {m}_t^2/s , {m}_t^2/t and {m}_t^2/u and show that precise results can be obtained down to energies which are fairly close to the top quark pair threshold. We present results both for the form factors and the next-to-leading order virtual cross-section.

Systematics of fully heavy tetraquarks

In this work, we systematically study the mass spectrum of the fully heavy tetraquark in an extended chromomagnetic model, which includes both color and chromomagnetic interactions. Numerical results indicate that the energy level is mainly determined by the color interaction, which favors the color-sextet $|(QQ{)}^{{6}_{c}}(\overline{Q}\overline{Q}{)}^{{\overline{6}}_{c}}⟩$ configuration over the color-triplet $|(QQ{)}^{{\overline{3}}_{c}}(\overline{Q}\overline{Q}{)}^{{3}_{c}}⟩$ one. The chromomagnetic interaction mixes the two color configurations and gives small splitting. The ground state is always dominated by the color-sextet configuration. We find no stable state below the lowest heavy quarkonium pair thresholds. Most states may be wide since they have at least one $S$-wave decay channel into two $S$-wave mesons. One possible narrow state is the ${1}^{+}$ $bb\overline{b}\overline{c}$ state with a mass 15719.1 MeV. It is just above the ${\ensuremath{\eta}}_{b}{\overline{B}}_{c}$ threshold. But this channel is forbidden because of the conservation of the angular momentum and parity.

Lepton collider indirect signatures of dark CP-violation

We study an extension of the Standard Model (SM) in which two copies of the SM Higgs doublet are added to the scalar sector. These extra doublets do not develop a vacuum expectation value, hence, they are inert. This essentially leads to a 3-Higgs Doublet Model (3HDM) with 2 inert and 1 active scalar doublets, which we denote as I(2+1)HDM. We allow for CP-violation in the inert sector, where the lightest inert state is protected from decaying to SM particles through the conservation of a Z_2 symmetry, so that it is a Dark Matter (DM) candidate. For this scenario, we identify a smoking gun signature of dark CP-violation in the form of production thresholds of pairs of inert neutral Higgs bosons at an e^+e^- collider.

Methemoglobin Modulation as an Intravascular Contrast Agent for Magnetic Resonance Imaging: Proof of Concept.

Objective: The aim of this feasibility study was to investigate methemoglobin modulation in vivo as a potential magnetic resonance imaging (MRI) gadolinium based contrast agent (GBCA) alternative. Recently, gadolinium tissue deposition was identified and safety concerns were raised after adverse effects were discovered in canines and humans. Because of this, alternative contrast agents are warranted. One potential alternative is methemoglobinemia induction, which can create T1-weighted signal in vitro. Canines with hereditary methemoglobinemia represent a unique opportunity to investigate methemoglobin modulation. Our objective was to determine if methemoglobinemia could create high intravascular T1-signal in vivo with reversal using methylene blue.Methods: To accomplish this study, a 1.5-year-old male-castrated mixed breed canine with hereditary methemoglobinemia underwent 3T-MRI/MRA with T1-weighted sequences including 3D-T1-weighted Magnetization Prepared Rapid Acquisition Gradient Echo (MPRAGE) and 3D-Time-Of-Flight (TOF). Images were acquired during baseline methemoglobinemia and rescued using intravenous methylene blue (1 mg/kg). Intravascular T1-signal was compared between baseline methemoglobinemia and post-methylene blue. N = 10 separate T1-signal measurements were acquired for each vascular structure, normalized to muscle. Significance was determined using paired two-tailed t-tests and threshold alpha = 0.05. Fold-change was also calculated using the ratio of T1-signal between methemoglobinemia and post-methylene blue states.Results: At baseline, methemoglobin levels measured 19.5% and decreased to 4.9% after methylene blue. On 3D-T1-weighted MPRAGE, visible signal change was present in internal vertebral venous plexus (IVVP, 1.34 ± 0.09 vs. 0.83 ± 0.05, p < 0.001, 1.62 ± 0.06-fold) and external jugular veins (1.54 ± 0.07 vs. 0.87 ± 0.06, p < 0.001, 1.78 ± 0.10-fold). There was also significant change in ventral spinal arterial signal (1.21 ± 0.11 vs. 0.79 ± 0.07, p < 0.001, 1.54 ± 0.16-fold) but not in carotid arteries (2.12 ± 0.10 vs. 2.16 ± 0.11, p = 0.07, 0.98 ± 0.03-fold). On 3D-TOF, visible signal change was in IVVP (1.64 ± 0.14 vs. 1.09 ± 0.11, p < 0.001, 1.50 ± 0.11-fold) and there was moderate change in external jugular vein signal (1.51 ± 0.13 vs. 1.19 ± 0.08, p < 0.001, 1.27 ± 0.07-fold). There were also small but significant differences in ventral spinal arterial signal (2.00 ± 0.12 vs. 1.78 ± 0.10, p = 0.002, 1.13 ± 0.10-fold) but not carotid arteries (2.03 ± 0.17 vs. 1.99 ± 0.17, p = 0.15, 1.02 ± 0.04-fold).Conclusion: Methemoglobin modulation produces intravascular contrast on T1-weighted MRI in vivo. Additional studies are warranted to optimize methemoglobinemia induction, sequence parameters for maximal tissue contrast, and safety parameters prior to clinical implementation.

Defining Time-to-Collision Thresholds by the Type of Lead Vehicle in Non-Lane-Based Traffic Environments

While anecdotal evidence suggests the consideration of a constant time-to-collision (TTC) threshold in advanced driver assistance systems, yet the prospect of the warning criterion acting as a catalyst for the evaluation of conflict severities in non-lane based traffic environments needs further assessment. The current study attempts to provide a copula-based framework to capture the potential dependence between TTC and centerline separation between the interacting vehicles in staggered-following events according to lead vehicle type. Detailed trajectory data extracted from the video footage of urban roads were used for the purpose of this study. Considering negative association between the considered variables and checked by the performance measures, the bivariate Frank copula model is found acceptable to model the bivariate dependency structure between TTC and CS. In particular, the results of the study corroborate a pragmatic decreasing relationship of TTC with increasing CS and decrease in lead vehicle size- a finding which indicates that the risk level of riders in staggered-following scenario varies by the type of front vehicle ahead and the lateral positioning of the vehicles. Based on the results presented in this paper, our recommendation is to use different minimum TTC thresholds for different centerline separations and leader-follower pairs to suitably evaluate traffic safety in such non-lane based traffic environments.

The Optimal Thresholds of Pairs Trading with a Stop-Loss Condition

The Optimal Thresholds of Pairs Trading with a Stop-Loss Condition

All-heavy tetraquarks

In this work we study the mass spectra of the fully-heavy tetraquark systems, i.e. $cc\bar{c}\bar{c}$, $bb\bar{b}\bar{b}$, $bb\bar{c}\bar{c}/cc\bar{b}\bar{b}$, $bc\bar{c}\bar{c}/cc\bar{b}\bar{c}$, $bc\bar{b}\bar{b}/bb\bar{b}\bar{c}$, and $bc\bar{b}\bar{c}$, within a potential model by including the linear confining potential, Coulomb potential, and spin-spin interactions. It shows that the linear confining potential has important contributions to the masses and is crucial for our understanding of the mass spectra of the fully-heavy tetraquark systems. For the fully-heavy tetraquarks $Q_1Q_2\bar{Q}_3\bar{Q}_4$ our explicit calculations suggest that no bound states can be formed below the thresholds of any meson pairs $(Q_1\bar{Q}_3)$-$(Q_2\bar{Q}_4)$ or $(Q_1\bar{Q}_4)$-$(Q_2\bar{Q}_3)$. Thus, we do not expect narrow fully-heavy tetraquark states to be existing in experiments.

Radiative and pionic transitions Zc(4020)0→X(3872)γ and Zc(4020)±→X(3872)π±

The radiative transitions from the neutral exotic $Z_c(4020)^0$ resonance to $X(3872)$ with emission of a photon and the pionic transitions from the charged $Z_c(4020)^\pm$ to $X(3872)$ and a charged pion $\pi^\pm$ are considered for both charmoniumlike states being charmed meson-antimeson molecules. The underlying processes for these transitions are the decays of the charmed vector meson to pseudoscalar plus a photon or a pion. It is found that the discussed transition rates typically amount to a branching fraction of several permil with a peak at the vector meson pair threshold.

Quantification of DNA double-strand breaks using Geant4-DNA.

PurposeThis study aims to standardize the simulation procedure in measuring DNA double‐strand breaks (DSBs), by using advanced Monte Carlo toolkits, and newly introduced experimental methods for DNA DSB measurement.MethodsFor the experimental quantification of DNA DSB, an innovative DNA dosimeter was used to produce experimental data. GATE in combination with Geant4‐DNA toolkit were exploited to simulate the experimental environment. The PDB4DNA example of Geant4‐DNA was upgraded and investigated. Parameters of the simulation such energy threshold (ET) for a strand break and base pair threshold (BPT) for a DSB were evaluated, depending on the dose.ResultsSimulations resulted to minimum differentiation in comparison to experimental data for ET = 19 ± 1 eV and BPT = 10 bp, and high differentiation for ET<17.5 eV or ET>22.5 eV and BPT = 10 bp. There was also small differentiation for ET = 17.5 eV and BPT = 6 bp. Uncertainty has been kept lower than 3%.ConclusionsThis study includes first results on the quantification of DNA double‐strand breaks. The energy spectrum of a LINAC was simulated and used for the first time to irradiate DNA molecules. Simulation outcome was validated on experimental data that were produced by a prototype DNA dosimeter.

A non-relativistic model for the tetraquark**The authors acknowledge the support received from the brazilian funding agencies FAPESP (contract 12/50984-4), CNPq and CAPES. V. R. Debastiani also acknowledges the support from Generalitat Valenciana in the Program Santiago Grisolia (Exp. GRISOLIA/2015/005)

We use a non-relativistic model to study the spectroscopy of a tetraquark composed of in a diquark-antidiquark configuration. By numerically solving the Schrödinger equation with a Cornell-inspired potential, we separate the four-body problem into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and tensor) are used to describe the splitting structure of the spectrum and are also extended to the interaction between diquarks. Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained. We find that the spin-dependent interaction is sizable in the diquark-antidiquark system, despite the heavy diquark mass, and also that the diquark has a finite size if treated in the same way as the systems. We find that the lowest S-wave T4c tetraquarks might be below their thresholds of spontaneous dissociation into low-lying charmonium pairs, while orbital and radial excitations would be mostly above the corresponding charmonium pair thresholds. Finally, we repeat the calculations without the confining part of the potential and obtain bound diquarks and bound tetraquarks. This might be relevant to the study of exotic charmonium in the quark-gluon plasma. The T4c states could be investigated in the forthcoming experiments at the LHC and Belle II.

Discordance in Xpert® MTB/RIF assay results among low bacterial load clinical specimens in Bangladesh.

The Xpert® MTB/RIF assay detects Mycobacterium tuberculosis (MTB) and rifampicin (RIF) resistance. RIF-resistant (RIF-R) MTB cases detected using Xpert on sputum specimens at three private-sector TB screening centres in Dhaka, Bangladesh, were subjected to consecutive confirmatory Xpert testing, the results of which were MTB-positive/RIF-susceptible, MTB-positive/RIF-indeterminate or MTB-negative. To assess the possible causes of discordant MTB and RIF-R results. Discordant confirmatory Xpert test results were subjected to further investigations using the GenoType® MTBDRplus assay, culture and rpoB gene sequencing. The confirmatory Xpert test was performed on a remnant or a second specimen collected from individuals with an initial RIF-R result (n = 69); 22 (32%) results were discordant, 20 of which had an 'MTB detected-very low' result. Further investigations were mostly concordant with the confirmatory Xpert test. Average variability in paired cycle threshold (Ct) values were higher in 'MTB detected-very low' results vs. specimens with low, medium or high detected MTB results (P < 0.05); discordant results were mostly observed in specimens with 'MTB detected-very low' (20/22). Repeating the Xpert test and comparing with other available tests should be considered in case of 'MTB detected-very low, RIF resistance detected' results on Xpert.

Higgs boson pair production at future hadron colliders: From kinematics to dynamics

The measurement of the triple Higgs coupling is a key benchmark for the LHC and future colliders. It directly probes the Higgs potential and its fundamental properties in connection to new physics beyond the Standard Model. There exist two phase space regions with an enhanced sensitivity to the Higgs self-coupling, the Higgs pair production threshold and an intermediate top pair threshold. We show how the invariant mass distribution of the Higgs pair offers a systematic way to extract the Higgs self-coupling, focusing on the leading channel $pp\to hh+X\to b\bar b\ \gamma\gamma+X$. We utilize new features of the signal events at higher energies and estimate the potential of a high-energy upgrade of the LHC and a future hadron collider with realistic simulations. We find that the high-energy upgrade of the LHC to 27 TeV would reach a 5$\sigma$ observation with an integrated luminosity of 2.5 ab$^{-1}$. It would have the potential to reach 15% (30%) accuracy at the 68% (95%) confidence level to determine the SM Higgs boson self-coupling. A future 100 TeV collider could improve the self-coupling measurement to better than 5% (10%) at the 68% (95%) confidence level.

Paired threshold graphs

Threshold graphs are recursive deterministic network models that have been proposed for describing certain economic and social interactions. One drawback of this graph family is that it has limited generative attachment rules. To mitigate this problem, we introduce a new class of graphs termed Paired Threshold (PT) graphs described through vertex weights that govern the existence of edges via two inequalities. One inequality imposes the constraint that the sum of weights of adjacent vertices has to exceed a specified threshold. The second inequality ensures that adjacent vertices have a weight difference upper bounded by another threshold. We provide a conceptually simple characterization and decomposition of PT graphs, analyze their forbidden induced subgraphs and present a method for performing vertex weight assignments on PT graphs that satisfy the defining constraints. Furthermore, we describe a polynomial-time algorithm for recognizing PT graphs. We conclude our exposition with an analysis of the intersection number, diameter and clustering coefficient of PT graphs.

Hadron Form Factors at BESIII

Form factors of hadron provide fundamental information about its structure and dynamics. They constitute a rigorous test of non-perturbative QCD as well as of phenomenological models. Based on data samples collected with BESIII detector at BEPCII collider, born cross section of [Formula: see text] and proton effective form factors are measured at 12 center-of-mass energies between 2.2324 and 3.671 GeV. The ratio [Formula: see text]s are extracted by fitting polar angle distribution of proton for data samples with large statistics. For data between 3.773 and 4.6 GeV, we use initial state radiation (ISR) method to study [Formula: see text] by tagged or un-tagged ISR photon, where the pair cross section, effective form factors and [Formula: see text]s are obtained from proton pair threshold to about 3 GeV. For [Formula: see text] and [Formula: see text], the pair cross section and [Formula: see text] form factors are measured near threshold. With data scanned in 2015 from 2-3.08 GeV, charged Kaon pair cross section and form factors are measured at 21 center-of-mass energies.

Mixing model for bottomoniumlike Zb resonances

The isovector bottomoniumlike exotic resonances $Z_b(10610)$ and $Z_b(10650)$ are very close to the thresholds of heavy meson pairs $B \bar B^* \, ( \bar B B^*)$ and $B^* \bar B^*$, and are naturally understood as `molecular' states made of the corresponding meson-antimeson pairs. The picture with a full separation of the two channels cannot be exact and a cross-feed between the states necessarily takes place. A simple model is considered here describing the mixing between the channels in terms of one parameter. The model reasonably describes the current data on the decays of the $Z_b$ resonances to bottomonium plus a pion and predicts the rate and a distinctive interference pattern for the decay $Z_b(10650) \to B \bar B^* \, ( \bar B B^*)$ as well as excess of the mass splitting between the resonances over the mass difference between $B^*$ and $B$ mesons.

Some properties of the states at the hidden-strangeness mixed 12++12− heavy meson pair threshold in e+e− annihilation

The threshold behavior of $e^+ e^-$ annihilation is considered in the channels $B_{s0} \bar B_s^* + c.c.$, $B_{s1} \bar B_s + c.c.$, and $B_{s1} \bar B_s^* +c.c.$, where $B_{s0}$ and $B_{s1}$ are the excited bottom-strange $J^P=0^+$ and $J^P = 1^+$ mesons. It is argued that due to the heavy quark spin symmetry (HQSS) only one coherent combination of the first two channels is produced in the $S$ wave as well as the third channel. Thus, if there exist threshold molecular peaks in the considered channels, only two of such peaks can be formed in the annihilation. The properties of such threshold states are discussed, including the heavy-light spin structure and the related transitions to bottomonium plus light mesons, as well as mixing with the channels with and without hidden strangeness.

The arc space of the Grassmannian

We study the arc space of the Grassmannian from the point of view of the singularities of Schubert varieties. Our main tool is a decomposition of the arc space of the Grassmannian that resembles the Schubert cell decomposition of the Grassmannian itself. Just as the combinatorics of Schubert cells is controlled by partitions, the combinatorics in the arc space is controlled by plane partitions (sometimes also called 3d partitions). A combination of a geometric analysis of the pieces in the decomposition and a combinatorial analysis of plane partitions leads to invariants of the singularities. As an application we reduce the computation of log canonical thresholds of pairs involving Schubert varieties to an easy linear programming problem. We also study the Nash problem for Schubert varieties, showing that the Nash map is always bijective in this case.