Best-fit Parameter Values Research Articles

1313. MIC Profiling of Ceftazidime-Avibactam (CAZ/AVI) Against Two Carbapenemase producing Klebsiella pneumoniae Isolates

BackgroundCarbapenemases confer resistance against a broad range of beta-lactams with a prevalence of 40-60% among CRE (carbapenem-resistant Enterobacteriaceae). CAZ-AVI is commonly used to treat infections due to CPE (carbapenemase-producing Enterobacteriaceae), typically guided by susceptibility testing with a single AVI concentration. This methodology does not take into consideration varying AVI concentration observed in vivo, and may not reliably predict positive clinical outcomes. Our objective was to investigate a novel susceptibility testing method to guide CAZ-AVI therapy.MethodsTwo bloodstream K. pneumoniae isolates (CAZ/AVI susceptible) from an abdominal source were recovered from 2 unrelated patients. Both patients were treated with CAZ/AVI, but had discordant outcomes: KP118 (eradication within 24h) and KP286 (persistent bacteremia for over 30 days). Carbapenemase production in the 2 isolates was confirmed via Carba NP test, and CAZ susceptibility was determined in a clinically relevant range of AVI concentration (0 - 16 mg/L). The concentration-response was characterized by the sigmoid inhibitory maximum effect (Emax) model. The best-fit parameter values were used to predict %T > MICi associated with CAZ/AVI exposures expected in peritoneal fluid after standard dosing (2.5g q8h). These CAZ/AVI exposures were simulated in the hollow-fiber infection model (HFIM), and the bacterial responses were correlated to observed clinical outcomes.ResultsThe AVI-dependent reduction in CAZ MIC was well characterized in both strains (R2 > 0.98). In HFIM, sustained suppression of KP118 (T > MICi = 100%) was observed over 5 days, but not with KP286 (T > MICi < 100%). These observations are consistent with the clinical courses of the patients.ConclusionThe discordant patient outcomes could be explained by MIC profiling of CAZ/AVI. This method appears to be more robust than conventional susceptibility testing, and the clinical utility of this approach should be further investigated.Disclosures All Authors: No reported disclosures

A search for the dimuon decay of the Standard Model Higgs boson with the ATLAS detector

A search for the dimuon decay of the Standard Model (SM) Higgs boson is performed using data corresponding to an integrated luminosity of 139 fb−1 collected with the ATLAS detector in Run 2 pp collisions at s=13 TeV at the Large Hadron Collider. The observed (expected) significance over the background-only hypothesis for a Higgs boson with a mass of 125.09 GeV is 2.0σ (1.7σ). The observed upper limit on the cross section times branching ratio for pp→H→μμ is 2.2 times the SM prediction at 95% confidence level, while the expected limit on a H→μμ signal assuming the absence (presence) of a SM signal is 1.1 (2.0). The best-fit value of the signal strength parameter, defined as the ratio of the observed signal yield to the one expected in the SM, is μ=1.2±0.6.

MIC profiling of ceftazidime/avibactam against two carbapenemase-producing Klebsiella pneumoniae isolates

ObjectivesThe aim of this study was to correlate the results of a modified susceptibility testing method with outcomes of ceftazidime/avibactam (CAZ/AVI) therapy. MethodsTwo bloodstream K. pneumoniae isolates (CAZ/AVI-susceptible) from an abdominal source were recovered from two unrelated patients. Both patients were treated with CAZ/AVI but had discordant outcomes: KP118 (eradication within 24 h) and KP286 (persistent bacteraemia for over 30 days). Carbapenemase production in the two isolates was confirmed by Carba NP test. The CAZ minimum inhibitory concentration (MIC) was determined with escalating AVI concentrations (0–16 mg/L). The concentration–response was characterised by the sigmoid inhibitory maximum effect model. The best-fit parameter values were used to predict %T > MICi associated with CAZ/AVI exposures expected in peritoneal fluid after standard dosing (2.5 g every 8 h). These CAZ/AVI exposures were simulated in a hollow-fibre infection model (HFIM), and the bacterial responses were correlated with observed clinical outcomes. ResultsThe AVI-dependent reduction in CAZ MIC was well characterised in both bacterial isolates (r2 ≥ 0.98). In the HFIM, sustained suppression of KP118 (T > MICi = 100%) was observed over 5 days, but not with KP286 (T > MICi < 100%). These observations are consistent with the clinical course of the patients. ConclusionsThe discordant patient outcomes could be potentially explained by MIC profiling of CAZ/AVI. This method appears to be more robust than conventional susceptibility testing in predicting positive clinical outcome of CAZ/AVI therapy, and the clinical utility of this approach should be further investigated.

Primordial universe with the running cosmological constant

Theoretically, the running of the cosmological constant in the IR region is not ruled out. On the other hand, from the QFT viewpoint, the energy released due to the variation of the cosmological constant in the late Universe cannot go to the matter sector. For this reason, the phenomenological bounds on such a running are not sufficiently restrictive. The situation can be different in the early Universe when the gravitational field was sufficiently strong to provide an efficient creation of particles from the vacuum. We develop a framework for systematically exploring this possibility. It is supposed that the running occurs in the epoch when the Dark Matter already decoupled and is expanding adiabatically, while the usual matter should be regarded approximately massless and can be abundantly created from vacuum due to the decay of vacuum energy. By using the handy model of Reduced Relativistic Gas for describing the warm Dark Matter, we consider the dynamics of both cosmic background and linear perturbations and evaluate the impact of the vacuum decay on the matter power spectrum and to the first CMB peak. Additionally, using the combined SNIa+BAO data, we find the best-fit values for the free parameters of the model.

Modeling and analysis of a H1N1 model with relapse and effect of Twitter

Twitter can play an important role in the control of influenza epidemics. We introduce a quantitative approach to evaluate the effects of Twitter on the modeling of the spread of influenza epidemics in this paper. Statistically significant correlations between the number of the percentage of tweets that are self-reporting flu and data of influenza-like illness reported cases are found from Pearson correlation and cross-correlation analyses, during the 2009 H1N1 flu outbreak in England. A new H1N1 model with relapse which involves impact of Twitter are also proposed. Stability of all the equilibria of our model are obtained. The occurrence of backward and forward bifurcation are also established. The best-fit parameter values in our model are identified by gray wolf optimizer and nonlinear least square method from the above data. For determining key parameters during the outbreak of the disease with Twitter impact, the uncertainty and sensitivity analyses are explored by using a Latin hypercube sampling (LHS) method and evaluating the partial rank correlation coefficients (PRCCs). Our results show that Twitter reports have important implications for the control of infectious diseases and Twitter can serve as a good indicator of influenza epidemics.

Viscous Ricci dark energy model with matter creation: Exact solution and observational tests

In this paper, the dissipative mechanism (bulk viscosity and matter creation) is introduced to describe the effects of cosmic non-perfect fluid on the Ricci dark energy (RDE) model. We consider matter creation and bulk viscosity as two independent irreversible processes. Assuming suitable forms of the bulk viscous coefficient and matter creation rate, we find the exact solution of the field equations. We carry out fitting analysis on the cosmological parameters in the model by using Type Ia supernovae data, observational Hubble data and baryon acoustic oscillation (BAO) data with cosmic microwave background. We plot the trajectory of cosmological parameters with the best-fit values of model parameters and discuss all possible (deceleration, acceleration and their transitions) evolutions of the model. The current values of deceleration parameter and equation of state parameter are found to be $$q_0=-0.362$$ and $$\omega _{\mathrm {eff}}=-0.575$$ , respectively. The age of the Universe is found to be $$t_0\simeq 13.397$$ Gyr, which is very close to the $$\Lambda $$ CDM model. We further discuss the geometrical diagnostic parameters such as statefinder and Om to distinguish the model with $$\Lambda $$ CDM model. Finally, we discuss the behaviour of energy conditions for our model and find that the model satisfies the null energy condition (NEC), weak energy condition (WEC) and dominant energy condition (DEC) while it violates strong energy condition (SEC).

Impact of media reports on the early spread of COVID-19 epidemic

Media reports can modify people’s knowledge of emerging infectious diseases, and thus changing the public attitudes and behaviors. However, how the media reports affect the development of COVID-19 epidemic is a key public health issue. Here the Pearson correlation and cross-correlation analyses are conducted to find the statistically significant correlations between the number of new hospital notifications for COVID-19 and the number of daily news items for twelve major websites in China from January 11th to February 6th 2020. To examine the implication for transmission dynamics of these correlations, we proposed a novel model, which embeds the function of individual behaviour change (media impact) into the intensity of infection. The nonlinear least squares estimation is used to identify the best-fit parameter values in the model from the observed data. To determine impact of key parameters with media impact and control measures for the later outcome of the outbreak, we also carried out the uncertainty and sensitivity analyses. These findings confirm the importance of the responses of individuals to the media reports, and the crucial role of experts and governments in promoting the public under self-quarantine. Therefore, for mitigating epidemic COVID-19, the media publicity should be focused on how to guide people’s behavioral changes by experts, and the management departments and designated hospitals of the COVID-19 should take effective quarantined measures, which are critical for the control of the disease.

Probing kinematics and fate of Bianchi type I universe in Brans–Dicke theory

In this paper, we examine the existence of Bianch type I Brans–Dicke universe by performing statistical test from [Formula: see text] and SN Ia observational data sets. We find that anisotropic Brans-Dicke ([Formula: see text] BD) model provides a reasonable fit with observational data. In addition to [Formula: see text], we also use Akaike information creation (AIC) and Bayes information creation (BIC) to determine the values of best fit parameters. The model under consideration represents a transitioning universe from early decelerating phase to current accelerating phase. We obtain the present age of the universe as 13.732 Gyrs, which is in good agreement with WMAP observations. The physical behavior of particle horizon and [Formula: see text] parameter of the derived model are also discussed.

Modeling the Effects of Meteorological Factors and Unreported Cases on Seasonal Influenza Outbreaks in Gansu Province, China.

Influenza usually breaks out seasonally in temperate regions, especially in winter, infection rates and mortality rates of influenza increase significantly, which means that dry air and cold temperatures accelerate the spread of influenza viruses. However, the meteorological factors that lead to seasonal influenza outbreaks and how these meteorological factors play a decisive role in influenza transmission remain unclear. During the epidemic of infectious diseases, the neglect of unreported cases leads to an underestimation of infection rates and basic reproduction number. In this paper, we propose a new non-autonomous periodic differential equation model with meteorological factors including unreported cases. First, the basic reproduction number is obtained and the global asymptotic stability of the disease-free periodic solution is proved. Furthermore, the existence of periodic solutions and the uniformly persistence of the model are demonstrated. Second, the best-fit parameter values in our model are identified by the MCMC algorithm on the basis of the influenza data in Gansu province, China. We also estimate that the basic reproduction number is 1.2288 (95% CI:(1.2287, 1.2289)). Then, to determine the key parameters of the model, uncertainty and sensitivity analysis are explored. Finally, our results show that influenza is more likely to spread in low temperature, low humidity and low precipitation environments. Temperature is a more important factor than relative humidity and precipitation during the influenza epidemic. In addition, our results also show that there are far more unreported cases than reported cases.

Observational constraints on holographic dark energy model with matter creation

In this paper, we consider a holographic dark energy model driven by the gravitationally induced adiabatic matter creation with constant creation rate. It is assumed that the present accelerating stage is a consequence of the negative pressure describing the irreversible process of gravitational matter creation. Exact solutions are obtained to discuss the evolution of the universe. We obtain the best-fit values of the model parameters through MCMC method by the use of EMCEE python package on latest observational data. With the best-fit values, it is found that the universe shows transition from decelerated phase to accelerated phase. We carry out the diagnostic analysis to distinguish our model with other standard dark energy models. We also discuss the cosmography analysis of our model. We analyse the model by applying Akaike information criterion (AIC) and Bayesian information criterion (BIC) based on the penalization associated to the number of parameters. The results show that the model behaves quintessence like and approaches to $\Lambda $ CDM model in late time.

Multisensory Integration Develops Prior to Crossmodal Recalibration.

It has been hypothesized that crossmodal recalibration plays a crucial role for the development of multisensory integration capabilities [1]. To test the developmental trajectory of multisensory integration and crossmodal recalibration, we used a combined ventriloquist/ventriloquist aftereffect paradigm [2] in children aged 5-9 years. The ventriloquist effect (indicating multisensory integration), that is, the shift of auditory localization toward simultaneously presented but spatially discrepant visual stimuli, was larger in children than in adults, which was attributed to a lower auditory localization precision in the children. In fact, the size of the ventriloquist effect depended on the visual stimulus reliability in both children and adults. In all groups, the ventriloquist effect was best explained by a causal inference model. In contrast to their multisensory integration capabilities, 5-year-old children did not recalibrate. The immediate ventriloquist aftereffect (indicating recalibration after a single exposure to a spatially discrepant audio-visual stimulus) emerged in 6- to 7-year-old children, whereas the cumulative ventriloquist aftereffect (reflecting recalibration to the audio-visual spatial discrepancies over the complete experiment) was not observed before the age of 8 years. First, in contrast to common beliefs, the present results provide evidence that multisensory integration precedes rather than follows crossmodal recalibration during development. Second, we report developmental evidence for a dissociation of the processes involved in multisensory integration and immediate as well as cumulative recalibration. We speculate that multisensory integration is a prerequisite for crossmodal recalibration, because the multisensory percept, rather than unimodal cues, might comprise a crucial signal for the calibration of the sensory systems.

Implications of JLA data for k-essence model of dark energy with given equation of state

We investigated implications of recently released `Joint Light-curve Analysis' (JLA) supernova Ia (SNe Ia) data for dark energy models with time varying equation of state of dark energy, usually expressed as $w(z)$ in terms of variation with corresponding redshift $z$. From a comprehensive analysis of the JLA data, we obtain the observational constraints on the different functional forms of $w(z)$, corresponding to different varying dark energy models often considered in literature, \textit{viz.} CPL, JBP, BA and Logarithmic models. The constraints are expressed in terms of parameters ($w_a, w_b$) appearing in the chosen functional form for $w(z)$, corresponding to each of the above mentioned models. Realising dark energy with varying equation of state in terms of a homogeneous scalar field $\phi$, with its dynamics driven by a $k-$essence Lagrangian $L=VF(X)$ with a constant potential $V$ and a dynamical term $F(X)$ with $X=(1/2)\nabla^\mu\phi\nabla_\mu\phi$ we reconstructed form of the function $F(X)$. This reconstruction has been performed for different varying dark energy models at best-fit values of parameters ($w_a, w_b$) obtained from analysis of JLA data. In the context of $k-$essence model, we also investigate the variation of adiabatic sound speed squared, $c_s^2(z)$, and obtained the domains in ($w_a, w_b$) parameter space corresponding to the physical bound $ c_s^2>0$ implying stability of density perturbations.

An improved ASM-GDA approach to evaluate the production kinetics of loosely bound and tightly bound extracellular polymeric substances in biological phosphorus removal process.

This study established an extended activated sludge model no. 2 (ASM2) for providing a new recognition of the contributions of both loosely-bound EPS (LB-EPS) and tightly-bound EPS (TB-EPS) into phosphorus (P) removal by incorporating their formation and degradation processes during the anaerobic–aerobic cycle. For determining the best-fit values for the new model parameters (kh,TB-EPS, kh,LB-EPS, fPP,TB-EPS, and fPP,LB-EPS) in this extended ASM2, a novel and convenient gradient descent algorithm (GDA) based ASM (ASM-GDA) method was developed. Sensitivity analysis of fPP,TB-EPS, fPP,LB-EPS, kh,TB-EPS, and kh,LB-EPS on the model target outputs of SPO4, XTB-EPS, XLB-EPS, and XPP proved the accuracy of the chosen parameters. Eight batch experiments conducted under different influential chemical oxygen demand (COD) and P conditions were quantitatively and qualitatively analyzed. Respectively, 9.37–9.64% and 4.17–4.29% of P removal by TB-EPS and LB-EPS were achieved. Self-Organizing Map (SOM) has shown its high performance for visualization and abstraction for exhibiting the high correlations of the influential COD/P concentrations and the P% removal by TB-EPS (and LB-EPS). Comprehensive analyses of the influences of influential COD and P concentration on the biological phosphorus removal process help us in successfully establishing the mechanism kinetics of production and degradation of P in a dynamic P biological-treatment model.

Probing bulk viscous matter-dominated model in Brans-Dicke theory

We explore a matter-dominated model with bulk viscosity in Brans-Dicke theory to interpret the observed cosmic accelerating expansion phenomena. We obtain the exact solution of the field equations by taking constant bulk viscous coefficient (which potentially could explain the present accelerated expansion of the Universe) and Brans-Dicke scalar field proportional to some power of the scale factor. The model is studied statistically using the available astronomical data and then compare using the tools taken from information criterion. Using the best-fit values of model parameters we find that the model shows transition from decelerated phase to accelerated phase. The effective equation of state parameter is within the quintessence region ($-1\leq \omega <0$). Thus, the model shows quintessence behavior and approaches to $\varLambda $CDM model in late time. It does not cross the phantom divide line and hence it is free from big-rip singularity. The viscous model also alleviates the age problem. We discuss two diagnostic parameters, namely statefinder and $Om(z)$ and compare the model with the existing models by plotting the trajectories. We also apply Akaike information criterion $(\mathit{AIC})$ and Bayesian information criterion $(\mathit{BIC})$ to discriminate the viscous model based on the penalization associated to the number of parameters. The analyses based on the $\mathit{AIC}$ indicates that there is less support for the viscous model when compared to the $\varLambda $CDM model, while those based on the $\mathit{BIC}$ indicates that there is strong evidence against it in favor of the $\varLambda $CDM model.

Kinetics study on esterification of acrylic acid and ethanol over acidic cation-exchange resin beads Amberlyst 35

Abstract The heterogeneous kinetics and adsorption behavior for the esterification of acrylic acid and ethanol were studied by using a fixed-bed reactor over an acidic cation-exchange resin beads, Amberlyst 35. The reaction experiments were conducted at 318.15 K–348.15 K under atmospheric pressure. The influences of molar ratios of ethanol to acrylic acid in the feed (θBo) and the mass transfer resistances on the kinetic behavior were also investigated. The experimental results show that the equilibrium conversion of acrylic acid increases with increasing reaction temperature and θBo. Moreover, the adsorption experiments were also made to determine the relative adsorption strengths among the reacting species. The results reveal that the magnitude of adsorption strengths obeyed the sequence of water > acrylic acid > ethanol > ethyl acrylate. The kinetic data obtained from the present study were correlated with the ideal-quasi-homogeneous (IQH), the non-ideal-quasi-homogeneous (NIQH), the Langmuir-Hinshelwood-Hougen-Waston (LHHW), the Eley-Rideal (ER) models, the modified LHHW (M-LHHW) and the modified ER (M-ER). The best-fitted values of the kinetic parameters were reported. The correlated results indicated that the M-LHHW model provides the best representation for this reaction system.

Probing galaxy cluster and intra-cluster gas with luminous red galaxies

We use the cross-correlation between the thermal Sunyaev-Zeldovich (tSZ) signal measured by the Planck satellite and the luminous red galaxy (LRG) samples provided by the SDSS DR7 to study the properties of galaxy cluster and intra-cluster gas. We separate the samples into three redshift bins z_1=(0.16, 0.26), z_2=(0.26, 0.36), z_3=(0.36, 0.47), and stack the Planck y-map against LRGs to derive the averaged y-profile for each redshift bin. We then fit the stacked profile with the theoretical prediction from the universal pressure profile (UPP) by using the Markov-Chain Monte-Carlo method. We find that the best-fit values of the UPP parameters for the three bins are generally consistent with the previous studies, except for the noticeable evolution of the parameters in the three redshift bins. We simultaneously fit the data in the three redshift bins together, and find that the original UPP model cannot fit the data at small angular scales very well in the first and third redshift bins. The joint fits can be improved by including an additional parameter eta to change the redshift-dependence of the model (i.e. E(z)^{8/3} -> E(z)^{8/3+eta}) with best-fit value as eta=-3.11^{+1.09}_{-1.13}. This suggests that the original UPP model with less redshift-dependence may provide a better fit to the stacked thermal Sunyaev-Zeldovich profile.

Observational constraints on EoS parameters of various modified Chaplygin gas models

Cosmological models of a class of modified Chaplygin gas as a candidate of unified dark matter and energy are studied to determine observational constraints on its EoS parameters using the background data. These data consist of $$H(z)-z$$ (OHD) data, baryonic acoustic oscillations peak parameter data, CMB shift parameter and SN Ia (Union 2.1) data. Best-fit value of present Hubble parameter ( $$H_{0}$$ ), present matter density ( $$\Omega _{m0}$$ ) and present age of the Universe ( $$t_{0}$$ ) has been determined in all these models. The acceptable range of values of the EoS parameters is determined in the analysis. Variations of EoS parameter ( $$\omega$$ ), squared sound speed ( $$c^2_{s}$$ ) and deceleration parameter (q) with redshift are also studied here. Akaike information criteria and Bayesian information criterion are used to check the suitability of the models. Density perturbation and CMB temperature anisotropy have also been studied.

Variable Chaplygin gas in Kaluza–Klein framework

We investigate cosmological features of the variable Chaplygin gas (VCG) describing a unified dark matter–energy scenario in a universe governed by the five dimensional (5D) Kaluza–Klein (KK) gravity. In such a proposal, the VCG evolves from the dust-like phase to the phantom or the quintessence phases. It is concluded that the background evolution for the KK-type VCG definition is equivalent to that for the dark energy interacting with the dark matter. Next, after performing neo-classical tests, we calculated the proper, luminosity, and angular diameter distances. Additionally, we construct a connection between the VCG in the KK universe and a homogenous minimally coupled scalar field by introducing its self-interacting potential and also we confirm the stability of the KK-type VCG model by making use of thermodynamics. Moreover, we use data from type Ia supernova, observational H(z) dataset and Planck-2015 results to place constraints on the model parameters. Subsequently, according to the best-fit values of the model parameters we analyze our results numerically.

Self-gravitating gaseous spheres in 5D framework

One of the suitable theoretical ideas for the polytrope in the Kaluza–Klein cosmology is discussed. Assuming a 5-dimensional (5D) spacetime model described by the Kaluza–Klein theory of gravity, we implement the energy density and pressure of the polytrope which is a self-gravitating gaseous sphere and still very useful as a crude approximation for more realistic stellar models. Next, we obtain the best-fit values of auxiliary parameters given in the model according to recent observational dataset. Finally, we study some cosmological features and the thermodynamical stability of the model.

A novel framework to compare the effectiveness of β-lactamase inhibitors against extended-spectrum β-lactamase-producing Enterobacteriaceae

ObjectivesExtended-spectrum β-lactamases (ESBLs) present a serious challenge in the treatment of Gram-negative bacterial infections. ESBLs mediate resistance to most β-lactams, which may be reversed with the addition of an active β-lactamase inhibitor (such as tazobactam, relebactam and avibactam). However, various ESBLs may exhibit different susceptibilities to these inhibitors, which could impact efficacy. We proposed a framework for comparing the efficacy of these inhibitors when combined with the same β-lactam. MethodsThree clinical isolates of Klebsiella pneumoniae harbouring CTX-M-15 and one Escherichia coli isolate with SHV-12 were examined. Piperacillin MICs were determined by broth dilution using escalating concentrations of tazobactam, relebactam and avibactam. The resulting MICs were characterized as response to inhibitor concentrations using an inhibitory sigmoid Emax model. Using the best-fit parameter values, the model was conditioned with fluctuating inhibitor concentrations to simulate instantaneous MICi profiles for each isolate–inhibitor pair. Using a simulated exposure of 4 g piperacillin every 8 h, %fT > MICi was estimated for each piperacillin/inhibitor combination. A hollowfibre infection model was subsequently used to validate the predicted effectiveness of selected combinations. ResultsIn all scenarios, piperacillin MIC reductions were well characterized with increasing inhibitor concentrations. As predicted by %fT > MICi, combining piperacillin with avibactam (61.4%–73.6%) was found to be superior to tazobactam (13.5%–44.5%) for suppressing bacterial growth over time. ConclusionWe illustrated a practical approach to compare the performance of different inhibitors. This platform may be used clinically to identify the optimal pairing of various β-lactams and β-lactamase inhibitors for individual isolates producing ESBLs.