Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

A comparative study on the anti-microbial activity of Mussa acuminate Colla (Banana blossom) and Allium Sativum (Garlic) extracts against Staphylococcus aureus and Escherichia coli

The plants were extracted using 95% ethanol and was subjected to a ROTAVAP machine. The extracts were evaluated using Disk Diffusion Method, Kirby-Bauer Test and Broth Macro Dilution. For the Kirby-Bauer Test, 100 mg/mL concentration of the extracts of Banana Blossom against Staphylococcus Aureus had an inhibition zone of 4mm (Trial 1) and 5mm (Trial 2) having a mean of 3 2.65. On the other hand, 100 mg/mL concentration of the extract of Garlic against Staphylococcus Aureus showed an inhibition zone of 6mm (Trial 1), 6mm (Trial 2) and 5mm (Trial 3) having a mean of 5.67 0.58. Ethanolic plant extracts showed antimicrobial activity against the Gram-positive and Gram-negative microorganisms

Charmonium and e(+)e(-) pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at root s(NN)=2.76 TeV

The ALICE Collaboration at the LHC has measured the J/psi and psi' photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at root s(NN) = 2.76 TeV. The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 mu b(-1). The cross section for coherent and incoherent J/psi production in the rapidity interval -0.9 e(+)e(-) has been measured and found to be in agreement with models implementing QED at leading order

Charmonium and e+e 12 pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at 1asNN = 2.76 Tev

The ALICE Collaboration at the LHC has measured the J/\u3c8 and \u3c8\u2032 photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at 1asNN = 2.76 Tev. The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 \u3bcb-1. The cross section for coherent and incoherent J/\u3c8 production in the rapidity interval -0.9<y<0.9, are d\u3c3J/\u3c8 coh/dy = 2.38-0.24 +0.34 (sta+sys) mb and d\u3c3J/\u3c8 inc/dy = 0.98-0.17 +0.19(sta+sys) mb, respectively. The results are compared to theoretical models for J/\u3c8 production and the coherent cross section is found to be in good agreement with those models incorporating moderate nuclear gluon shadowing at Bjorken-x around 10-3, such as EPS09 parametrization. In addition the cross section for the process \u3b3\u3b3\u2192e + e - has been measured and found to be in agreement with models implementing QED at leading order

Mid-rapidity anti-baryon to baryon ratios in pp collisions at sqrt(s) = 0.9, 2.76 and 7 TeV measured by ALICE

The ratios of yields of anti-baryons to baryons probes the mechanisms of baryon-number transport. Results for anti-p over p, anti-Lambda over Lambda, anti-Xi+ over Xi 12 and anti-Omega+ over Omega- in pp collisions at 1as = 0.9, 2.76 and 7 TeV, measured with the ALICE detector at the LHC, are reported. Within the experimental uncertainties and ranges covered by our measurement, these ratios are independent of rapidity, transverse momentum and multiplicity for all measured energies. The results are compared to expectations from event generators, such as PYTHIA and HIJING/B, that are used to model the particle production in pp collisions. The energy dependence of anti-p/p, anti-Lambda/Lambda, antiXi+/Xi- and anti-Omega+/Omega- , reaching values compatible with unity for 1as = 7 TeV, complement the earlier anti-p/p measurement of ALICE. These dependencies can be described by exchanges with the Regge-trajectory intercept of alpha_J 48 0.5, which are suppressed with increasing rapidity interval Delta_y. Any significant contribution of an exchange not suppressed at large Delat_y (reached at LHC energies) is disfavoure

Energy dependence of the transverse momentum distributions of charged particles in pp collisions measured by ALICE

Differential cross sections of charged particles in inelastic pp collisions as a function of pT have been measured at 1as = 0.9, 2.76 and 7 TeV at the LHC. The pT spectra are compared to NLO-pQCD calculations. Though the differential cross section for an individual 1as cannot be de- scribed by NLO-pQCD, the relative increase of cross section with 1as is in agreement with NLO-pQCD. Based on these measurements and observations, procedures are discussed to construct pp reference spectra at 1as = 2.76 and 5.02 TeV up to pT = 50 GeV/c as required for the calculation of the nuclear modification factor in nucleus\u2013nucleus and proton\u2013nucleus collisions