Search for magnetic monopoles produced via the Schwinger mechanism.

Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism1. By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles, if they exist2. Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model3-7 but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size8,9 and strong coupling to photons2,10. Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb-Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe11. It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 × 109, of Pb-Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.

MoEDAL Search in the CMS Beam Pipe for Magnetic Monopoles Produced via the Schwinger Effect.

We report on a search for magnetic monopoles (MMs) produced in ultraperipheral Pb-Pb collisions during Run 1 of the LHC. The beam pipe surrounding the interaction region of the CMS experiment was exposed to 184.07 µb^{-1} of Pb-Pb collisions at 2.76 TeV center-of-mass energy per collision in December 2011, before being removed in 2013. It was scanned by the MoEDAL experiment using a SQUID magnetometer to search for trapped MMs. No MM signal was observed. The two distinctive features of this search are the use of a trapping volume very close to the collision point and ultrahigh magnetic fields generated during the heavy-ion run that could produce MMs via the Schwinger effect. These two advantages allowed setting the first reliable, world-leading mass limits on MMs with high magnetic charge. In particular, the established limits are the strongest available in the range between 2 and 45 Dirac units, excluding MMs with masses of up to 80 GeV at a 95% confidence level.

First Search for Dyons with the Full MoEDAL Trapping Detector in 13 TeV pp Collisions.

The MoEDAL trapping detector consists of approximately 800 kg of aluminum volumes. It was exposed during run 2 of the LHC program to 6.46 fb^{-1} of 13 TeV proton-proton collisions at the LHCb interaction point. Evidence for dyons (particles with electric and magnetic charge) captured in the trapping detector was sought by passing the aluminum volumes comprising the detector through a superconducting quantum interference device (SQUID) magnetometer. The presence of a trapped dyon would be signaled by a persistent current induced in the SQUID magnetometer. On the basis of a Drell-Yan production model, we exclude dyons with a magnetic charge ranging up to five Dirac charges (5g_{D}) and an electric charge up to 200 times the fundamental electric charge for mass limits in the range 870-3120 GeV and also monopoles with magnetic charge up to and including 5g_{D} with mass limits in the range 870-2040 GeV.

Magnetic Monopole Search with the Full MoEDAL Trapping Detector in 13 TeV pp Collisions Interpreted in Photon-Fusion and Drell-Yan Production.

MoEDAL is designed to identify new physics in the form of stable or pseudostable highly ionizing particles produced in high-energy Large Hadron Collider (LHC) collisions. Here we update our previous search for magnetic monopoles in Run 2 using the full trapping detector with almost four times more material and almost twice more integrated luminosity. For the first time at the LHC, the data were interpreted in terms of photon-fusion monopole direct production in addition to the Drell-Yan-like mechanism. The MoEDAL trapping detector, consisting of 794 kg of aluminum samples installed in the forward and lateral regions, was exposed to 4.0 fb^{-1} of 13 TeV proton-proton collisions at the LHCb interaction point and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges equal to or above the Dirac charge are excluded in all samples. Monopole spins 0, ½, and 1 are considered and both velocity-independent and-dependent couplings are assumed. This search provides the best current laboratory constraints for monopoles with magnetic charges ranging from two to five times the Dirac charge.

Search for Magnetic Monopoles with the MoEDAL Forward Trapping Detector in 13 TeV Proton-Proton Collisions at the LHC.

MoEDAL is designed to identify new physics in the form of long-lived highly ionizing particles produced in high-energy LHC collisions. Its arrays of plastic nuclear-track detectors and aluminium trapping volumes provide two independent passive detection techniques. We present here the results of a first search for magnetic monopole production in 13 TeV proton-proton collisions using the trapping technique, extending a previous publication with 8 TeV data during LHC Run 1. A total of 222 kg of MoEDAL trapping detector samples was exposed in the forward region and analyzed by searching for induced persistent currents after passage through a superconducting magnetometer. Magnetic charges exceeding half the Dirac charge are excluded in all samples and limits are placed for the first time on the production of magnetic monopoles in 13 TeV pp collisions. The search probes mass ranges previously inaccessible to collider experiments for up to five times the Dirac charge.

Relationship between cognitive reserve, brain volume, and neuropsychological performance in amnestic and nonamnestic MCI.

Cognitive Reserve (CR) is a theoretical construct that influences the onset and course of cognitive and structural changes that occur with aging and mild cognitive impairment (MCI). There is a paucity of research that examines the relationship of CR and brain volumes in amnestic (aMCI) and nonamnestic (naMCI) separately. This study is a retrospective chart review of MCI patients who underwent neuropsychological evaluation and brain MRI with NeuroReader™ (NR). NR is an FDA-cleared software that standardizes MRI volumes to a control sample. Classifications of aMCI and naMCI were based on Petersen criteria. CR was measured as education, occupation, and word reading. Data analysis included bivariate correlations between CR, neuropsychological test scores, and NR-brain volumes by MCI subtype. The Benjamini-Hochberg method corrected for multiple comparisons. The sample included 91 participants with aMCI and 41 with naMCI. Within naMCI, positive correlations were observed between CR and whole brain volume, total gray matter, bifrontal, left parietal, left occipital, and bilateral cerebellum. Within aMCI, no significant correlations were observed between CR and brain volumes. Positive correlations with CR were observed in language, attention, and visual learning in both aMCI and naMCI groups. The current study adds to the minimal literature on CR and naMCI. Results revealed that CR is associated with volumetrics in naMCI only, though cognitive findings were similar in both MCI groups. Possible explanations include heterogeneous disease pathologies, disease stage, or a differential influence of CR on volumetrics in MCI. Additional longitudinal and biomarker studies will better elucidate this relationship.

Molecular evidence of Bartonella DNA in ixodid ticks in Czechia.

We report the development of a novel method for detection of Bartonella DNA in ixodid ticks. The assay is based on a specific amplification of a part of 16S rRNA gene and 16S-23S rRNA intergenic spacer region of Bartonella sp. by nested PCR and Southern blot hybridization with specific DNA probe; the method is highly sensitive and specific. The screening of 327 unfed ticks collected in different urban and suburban areas of Czechia in 2003-2005 revealed the presence of Bartonella DNA in four Ixodes ricinus individuals (1.2%), two males, one female and one nymph.

Effect of phosphate on the expression of protein-Ser/Thr kinase pkg2 in Streptomyces granaticolor.

A time-correlated expression of eukaryotic-like protein Ser/Thr kinase Pkg2 of Streptomyces granaticolor was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR) and by transcriptional fusion experiments. In a complex medium the activity of pkg2 promoter was constant during the life cycle. Direct RNA analysis proved the presence of corresponding pkg2 transcript. S1 nuclease protection analysis of the transcription initiation site showed that pkg2 gene is expressed as a leaderless mRNA. Under phosphate starvation the promoter activity was detectable merely in the early exponential phase. Under these conditions turning off of pkg2 promoter and cessation of pkg2 transcript level coincided with the start of granaticin production.

Protein phosphorylation in microorganisms.

The covalent modification of proteins by phosphorylation constitutes a major regulatory mechanism. It was first recognized in mammalian tissues. A conclusive evidence for the occurrence of protein phosphorylation and protein kinases in coliform bacteria was obtained in 1978. Several phosphate labeled proteins were found when Salmonella typhimurium was pulse-labeled with 32p(i) and solubilized bacterial contents were analyzed by SDS-polyacrylamide gel electrophoresis. In streptomycetes protein phosphorylation has not yet been demonstrated. We found that Streptomyces albus possesses a protein kinase activity. This in vitro protein phosphorylation is cAMP-independent.

Pattern of phosphoproteins during cell differentiation in Streptomyces collinus.

Transition from vegetative cells to aerial mycelium and spores of Streptomyces collinus is accompanied by changes in the pattern of proteins phosphorylated. Preparation from spores exhibits lower phosphorylation activity than those of vegetative cells and aerial mycelium. Phosphorylation of proteins from aerial mycelium was markedly stimulated by the presence of Mn2+. Our data indicate that phosphorylation of proteins on Ser/Thr residues is involved in transition of vegetative cells to aerial mycelium.

Protein phosphorylation in Streptomyces albus.

The phosphorylated proteins of Streptomyces albus, radioactively labeled with [32P]orthophosphate have been analyzed by gel electrophoresis and autoradiography. More than 10 protein species were found to be phosphorylated. With [32P]ATP as substrate cell free extracts phosphorylated endogenous proteins in vitro which were predominantly phosphorylated in vivo. From cell extract which exhibited active phosphorylated in vitro, a protein kinase has been partially purified. The kinase activity was identified in fractions corresponding to a 90 kDa protein.

Oxazepam in the treatment of anxiety states: a controlled study.

Twenty-six psychoneurotic inpatients received oxazepam (60-120 mg daily) or placebo for one to two weeks. The strongest evidence for the superiority of oxazepam over placebo was that a greater proportion of oxazepam-treated patients remained on the study the full two weeks than placebo-treated patients. Patients' self-evaluations on the MMPI also favored oxazepam. Behavioral ratings by clinicians and ward personnel on the BPRS, symptom checklist, and assessment of global disorder did not discriminate the active drug from placebo as well as self-ratings did. Most of the differences found favored oxazepam, although some failed to reach acceptable levels of significance. It is suggested that the relative similarity of neurotic individuals to normal individuals with respect to pathology (e.g. anxiety, tension, depression) and difficulties in life and that the subjectivity of experience and the absence of gross and easily demonstrable symptoms make evaluation of improvement difficult. Symptom measurement on behavioral rating devices is probably less effective in discriminating drug-placebo differences in neurotic syndromes than in psychotic syndromes.

Detection and characterization of feline Bartonella henselae in the Czech Republic.

The aims of the study were to characterize isolates of Bartonella henselae and to determine the prevalence of bacteremic domestic cats in urban and suburban parts of Prague, Czech Republic. Five (18%) gram-negative fastidious bacterial single-cat isolates were recovered from 27 hemocultures incubated without previous freezing. Four of these isolates originated from flea infested stray cats (n=6) and one from a shelter cat without any ectoparasites (n=21). None of the 34 previously frozen specimens from flea free pet cats yielded any bacteria. All five isolates were catalase and oxidase negative. Their enzymatic activity, RFLP profile of citrate synthetase gene (gltA) and DNA-DNA hybridization results were typical of B. henselae. According to their PvuII and BglI ribotypes the isolates could be allocated to two homogeneous groups. Ribotype HindIII and RFLP of 16S-23S rRNA spacer region analysis gave unique profiles different from those of Bartonella quintana, Bartonella elizabethae and Bartonella clarridgeiae. The 16S rRNA type-specific amplification revealed an identical profile typical of B. henselae genotype II for all the cat isolates studied. Pulsed-field gel electrophoresis (PFGE) assigned a different profile to each of the isolates studied. Determination of the enzymatic activity, RFLP of gltA gene, RFLP of 16S-23S rRNA spacer region, and HindIII ribotype could be efficient tools for identification of B. henselae isolates. Ribotyping (PvuII, BglI), 16S rRNA typing and PFGE may be useful methods to prospect ecology and epidemiology of the agent.

Improved method for rapid purification of protein kinase from streptomycetes.

Protein kinase from Streptomyces lincolnensis was purified nearly to homogeneity using a high performance liquid chromatography (HPLC) and a Pharmacia FPLC system. The procedure used employed column chromatography on DE-53, followed by FPLC affinity chromatography with serine- or threonine-Sepharose (prepared as described in this paper) and gel filtration using a Superose 12 or TSK G3000SW column. Starting with 3.5 g of mycelial proteins, approximately 1 mg of pure enzyme was obtained. The procedure is simple and highly reproducible. The protein kinase thus obtained was nearly pure by silver staining after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified protein kinase phosphorylated substrate proteins at the seryl residues.

Inhibition of beta-galactosidase synthesis in Escherichia coli after infection with different DNA and RNA phages.

Infection of Escherichia cooi with T1, T2r+, T3 and T4 phages leads to an immediate inhibition of beta-galactosidase synthesis. Similar results were obtained with the virulent mutant of phage lambda. The degree of inhibition of beta-galactosidase synthesis depends on the time delay between the addition of the inducer and the phage particles, and on the amount of phage DNA, which has penetrated into the host cell. RNA phage MS2 exhibited no inhibitory effect on enzyme synthesis.

The activity of Escherichia coli DNA-dependent RNA polymerase on DNA templates of different origin. The effect of cAMP.

DNA isolated from different T phages served as a better template for the synthetic activity of unmodified Escherichia coli RNA polymerase in the in vitro system than did the host DNA. cAMP significantly stimulated the activity of such a preparation of RNA polymerase. The stimulation was more pronounced with the host DNA template than with phage DNA. However, the synthetic activity of Escherichia coli RNA polymerase was greater in the presence of cAMP than without it when phage DNA served as the template.

Catabolite repression during single and multiple induction in Escherichia coli.

Intracellular concentration of cAMP regulates the synthesis of enzymes sensitive to catabolite repression. The relationship between the single and multiple induction of beta-galactosidase (EC 3.2.1.23), L-tryptophanase (EC 4.1.99.1), D-serine deaminase (EC 4.2.1.14), L-asparaginase (EC 3.5.1.1) and L-malate dehydrogenase (EC 1.1.1.37) was studied and the effect of cAMP level on the induction in Escherichia coli Crookes (ATCC 8739) was investigated. A varying degree of catabolite repression was observed during induction of individual enzymes induced separately on different energy sources. The synthesis of l-tryptophanase was most sensitive, whereas l-asparaginase was not influenced at all. Exogenous cAMP was found to overcome partially the catabolite repression of beta-galactosidase and D-serine deaminase, both during single induction. The synthesis of l-malate dehydrogenase was negatively influenced by the multiple induction even in the presence of cAMP; on the other hand, the synthesis of l-tryptophanase was stimulated, independently of the level of the exogenous cAMP. Similarly, the activity of L-asparaginase slightly but significantly increased during the multiple induction of all five enzymes; here too the activity increase did not depend on exogenous cAMP.

The effect of glucose on cellobiose uptake and beta-D-glucosidase activity in Streptomyces granaticolor.

Glucose inhibits the inducible synthesis of beta-D-glucosidase in Streptomyces granaticolor. Neither cAMP nor cGMP influence the inhibitory effect of glucose. Glucose also inhibits the inducible synthesis of the cellobiose uptake system but has no effect on its activity. This may be the mechanism underlying glucose inhibition of induction of beta-D-glucosidase in S. granaticolor.

Effect of protein phosphorylation on the activity of RNA polymerase in streptomycetes.

RNA polymerase was isolated from Streptomyces granaticolor and protein kinase was partially purified from Streptomyces albus. When RNA polymerase was treated with protein kinase in vitro the activity of RNA polymerase was markedly enhanced. Furthermore, a protein of M = 65 kDa was isolated which, after being phosphorylated, stimulated RNA polymerase activity in vitro. Because neither the beta-subunits nor the alpha-subunits of RNA polymerase were phosphorylated it is assumed that phosphorylation of the 65 kDa protein may regulate the activity of RNA polymerase in streptomycetes.

Constitution of the metabolic type of streptomycetes during the first hours of cultivation.

Using the examples of biosynthesis of streptomycin, bialaphos, actinorhodin, oligoketides and autoregulators during the first hours of streptomycete cultivation, it is stressed that the external environment in cooperation with the internal metabolic abilities of the cell determines the metabolic type that would develop during the life cycle of the producing streptomycetes. If we accept that a certain metabolic type (from the point of view of the production of secondary metabolites) was determined already during the first hours of cultivation of the microorganisms, we must also admit that the availability of primary metabolites in the so-called production phase of growth (stationary phase, idiophase, etc.) is to a certain extent determined by the very early stages of strain development.