Salmonella Typhimurium is a Gram-negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and ...proliferates inside a Salmonella-containing vacuole where Salmonella is exposed and survives oxidative stress induced by H
O
through modulation of gene expression. After exposure of Salmonella to H
O
, the expression of the porin-encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post-transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA.
In this work we sought to evaluate the transcriptional and post-transcriptional regulation of ompX under H
O
stress. We demonstrate that ompX expression is induced at the transcriptional level in S. Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H
O
does not translate into increased protein levels in the wild-type strain, suggesting that ompX mRNA is also regulated at a post-transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H
O
-induced stress in Salmonella during the exponential growth phase in Lennox broth.
Our results demonstrate that ompX mRNA is regulated in response to H
O
by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.
We discuss a technique for measuring a charged particle's momentum by means of multiple Coulomb scattering (MCS) in the MicroBooNE liquid argon time projection chamber (LArTPC). This method does not ...require the full particle ionization track to be contained inside of the detector volume as other track momentum reconstruction methods do (range-based momentum reconstruction and calorimetric momentum reconstruction). We motivate use of this technique, describe a tuning of the underlying phenomenological formula, quantify its performance on fully contained beam-neutrino-induced muon tracks both in simulation and in data, and quantify its performance on exiting muon tracks in simulation. Using simulation, we have shown that the standard Highland formula should be re-tuned specifically for scattering in liquid argon, which significantly improves the bias and resolution of the momentum measurement. With the tuned formula, we find agreement between data and simulation for contained tracks, with a small bias in the momentum reconstruction and with resolutions that vary as a function of track length, improving from about 10% for the shortest (one meter long) tracks to 5% for longer (several meter) tracks. For simulated exiting muons with at least one meter of track contained, we find a similarly small bias, and a resolution which is less than 15% for muons with momentum below 2 GeV/c. Above 2 GeV/c, results are given as a first estimate of the MCS momentum measurement capabilities of MicroBooNE for high momentum exiting tracks.
Liquid Argon Time Projection Chambers (LArTPCs) are ideally suited to perform long-baseline neutrino experiments aiming to measure CP violation in the lepton sector, and determine the ordering of the ...three neutrino mass eigenstates. LArTPCs have used projective wire readouts for charge detection since their conception in 1977. However, wire readouts are notoriously fragile and therefore a limiting factor in the design of any large mass detectors. Furthermore, a wire readout also introduces intrinsic ambiguities in event reconstruction. Within the ArgonCube concept—the liquid argon component of the DUNE near detector—we are developing a pixelated charge readout for LArTPCs. Pixelated charge readout systems represent the single largest advancement in the sensitivity of LArTPCs. They are mechanically robust and provide direct 3D readout, serving to minimise reconstruction ambiguities, enabling more advanced triggers, further reducing event pile-up and improving background rejection. This article presents first results from a pixelated LArTPC prototype built and operated in Bern.
NEW is the first phase of NEXT-100 experiment, an experiment aimed at searching for neutrinoless double-beta decay. NEXT technology combines an excellent energy resolution with tracking capabilities ...thanks to a combination of optical sensors, PMTs for the energy measurement and SiPMs for topology reconstruction. Those two tools result in one of the highest background rejection potentials in the field. This work describes the tracking plane that will be constructed for the NEW detector which consists of close to 1800 sensors with a 1-cm pitch arranged in twenty-eight 64-SiPM boards. Then it focuses in the development of the electronics needed to read the 1800 channels with a front-end board that includes per-channel differential transimpedance input amplifier, gated integrator, automatic offset voltage compensation and 12-bit ADC. Finally, a description of how the FPGA buffers data, carries out zero suppression and sends data to the DAQ interface using CERN RD-51 SRS's DTCC link specification complements the description of the electronics of the NEW detector tracking plane.
This paper describes the design and construction of the MicroBooNE liquid argon time projection chamber and associated systems. MicroBooNE is the first phase of the Short Baseline Neutrino program, ...located at Fermilab, and will utilize the capabilities of liquid argon detectors to examine a rich assortment of physics topics. In this document details of design specifications, assembly procedures, and acceptance tests are reported.
NEXT-DEMO is a prototype of NEXT (Neutrino Experiment with Xenon TPC), anexperiment to search for neutrino-less double beta decay using a 100 kg radio-pure, 90% enriched (136Xe isotope) high-pressure ...gaseous xenon TPC with electroluminescence readout. The detectoris based on a PMT plane for energy measurements and a SiPM tracking plane for topological eventfiltering. The experiment will be located in the Canfranc Underground Laboratory in Spain. Front-end electronics, trigger and data-acquisition systems (DAQ) have been built. The DAQis an implementation of the Scalable Readout System (RD51 collaboration) based on FPGA. Ourapproach for trigger is to have a distributed and reconfigurable system in the DAQ itself. Moreover, the trigger allows on-line triggering based on the detection of primary or secondary scintillationlight, or a combination of both, that arrives to the PMT plane.
Oxidative stress is the main mechanism behind efficient disinfectants, causing damage in bacterial macromolecules. Importantly, bacteria activate resistance mechanisms in response to damage generated ...by oxidative stress. Strategies allowing pathogens to survive oxidative stress are highly conserved among microorganisms. Many of these strategies entail genomic responses triggered by signals transduced through Two Component Systems (TCS). Recently, we demonstrated that the TCS ArcAB (specifically ArcA) participates in bacterial responses to hypochlorite, regulating the uptake of this toxic compound and being involved in resistance and survival inside neutrophils, where hypochlorous acid abounds. Here, we demonstrated that ArcA is required in the response to oxidative stress generated by hypochlorite, independent of its cognate sensor ArcB or the Asp54 of ArcA, the only phosphorylable residue in ArcA, which is required to function as a gene regulator. Our results suggest that ArcA could have additional functions to respond to oxidative stress, independent of its regulatory activity, which might require interaction with other unknown relevant proteins.
•ArcA is required in the response to oxidative stress generated by hypochlorite, independent of its cognate sensor ArcB.•Functionality of ArcA is independent of acetyl phosphate activity when the cell is under oxidative stress.•Our results suggest that ArcA is probably interacting with an unknown factor under the effect of Reactive Oxygen Species.
We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino ($\nu_{\mu}$) scattering on argon with a muon and a proton in the final ...state, 40Ar $(\nu_{\mu},μp)X$. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an exposure of 4.59 × 1019 protons on target. Events are selected to enhance the contribution of CC quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single differential cross sections in final state muon and proton kinematics. We measure the integrated per-nucleus CCQE-like cross section (i.e., for interactions leading to a muon, one proton, and no pions above detection threshold) of (4.93 ± 0.76stat ± 1.29sys)×10-38 cm2, in good agreement with theoretical calculations. The single differential cross sections are also in overall good agreement with theoretical predictions, except at very forward muon scattering angles that correspond to low-momentum-transfer events.
We describe the concept and procedure of drifted-charge extraction developed in the MicroBooNE experiment, a single-phase liquid argon time projection chamber (LArTPC). This technique converts the ...raw digitized TPC waveform to the number of ionization electrons passing through a wire plane at a given time. A robust recovery of the number of ionization electrons from both induction and collection anode wire planes will augment the 3D reconstruction, and is particularly important for tomographic reconstruction algorithms. A number of building blocks of the overall procedure are described. The performance of the signal processing is quantitatively evaluated by comparing extracted charge with the true charge through a detailed TPC detector simulation taking into account position-dependent induced current inside a single wire region and across multiple wires. Some areas for further improvement of the performance of the charge extraction procedure are also discussed.
PDF
