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.

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.

Polymorphonuclear leukocyte functions and multiple sclerosis.

We tested peripheral blood from 60 patients with definite multiple sclerosis (MS) and 60 healthy controls for polymorphonuclear leukocyte (PMNL) functions and found significant disorders in adherence (9.07% +/- 8.18% for patients versus 28.97% +/- 5.76% for controls), chemotaxis (18.32 +/- 3.1 for patients versus 30.49 +/- 4.52 for controls), phagocytosis (73.6 +/- 25.25 for patients versus 111.2 +/- 25.7 for controls), and bactericidal action (10.35% +/- 5% for patients versus 25.09% +/- 4.82% for controls). All differences were significant (p < 0.001). We confirmed the results by retesting 3 to 8 months later. The depressed PMNL functions in MS patients may explain their increased susceptibility to infections of the respiratory, digestive, and urinary tracts.

The pinch technique at two loops

It is shown that the fundamental properties of gauge independence, gauge invariance, unitarity, and analyticity of the S matrix lead to the unambiguous generalization of the pinch technique algorithm to two loops.

Characteristics of Pseudomonas aeruginosa in relation to laboratory-induced resistance to gentamicin.

Pseudomonas aeruginosa strain C2 was habituated to gentamicin by serial passage in broth containing increasing concentrations of the antibiotic and up to 250 microgram/ml. The resistant progenies differed from the parent strain in antibiotic susceptibility to two other aminoglycosides, colonial morphology, lytic phage patterns, phage adsorption, and agglutination with the seven Fisher's antisera. All the progenies failed to grow at 42 degrees C and oxidised glucose in O/F tubes after incubation at 37 degrees C for three days but were catalase- and oxidase-positive. Reversion to the original properties of the parent strain was demonstrated in all cases after 10 serial subcultures in antibiotic-free broth.

Differentiation of Serratia marcescens and Serratia liquefaciens by tests for lipase and phospholipase production.

The production of lipase and phospolipase by certain members of the Enterobacteriaceae was examined by thin-layer chromatography of resting-cell suspensions incubated with triolein or lecithin. Most strains of Serratia marcescens produced both enzymes while most strains of Serratia liquefaciens exhibited strong lipase but only a minor phospholipase activity. Enterobacter spp. (25 strains), Klebsiella pneumoniae (20 strains), Escherichia coli (15 strains), Citrobacter freundii (7 strains) and Proteus spp. (20 strains) lacked both types of enzymic activity except for the following: three strains of Enterobacter cloacae, two of Proteus mirabilis and three of Proteus vulgaris possessed slight lipase activity; about one-half of the Enterobacter aerogenes and Enterobacter hafniae strains examined produced slight phospholipase activity. It is suggested that tests for lipase and phospholipase should be used in conjunction with those for DNAase production and sugar fermentation for the differentiation of S. marcescens and S. liquefaciens.

Differences in adherence to buccal epithelial cells, in phagocytosis and in killing by neutrophils between human and non-human strains of Candida albicans.

The adherence of strains of Candida albicans to buccal epithelial cells as well as the phagocytosis of these organisms by human polymorphonuclear leucocytes (PMNL) was studied. The strains of C. albicans were obtained from patients' urine. from bird faeces and from soil. The strains of C. albicans obtained from patients and the environment displayed greater adhering ability (23.8 +/- 6.4 and 27.5 +/- 5.2 respectively) than the avian strains (14.4 +/- 2.2) (P < 0.01). Strains obtained from the environment were resistant to phagocytosis (81.6 +/- 0.2 organisms ingested per 200 PMNL) and killing (8.4 +/- 2.6%) by PMNL as compared to human and avian strains (P < 0.01). These observations indicate that environmental strains of C. albicans may be more virulent for human beings.

Phagocytosis and antimicrobicidal activity of polymorphonuclear leucocytes against gentamicin-sensitive and resistant strains of Pseudomonas aeruginosa.

The ability of human polymorphonuclear leucocytes (PMNs) to ingest and kill gentamicin-sensitive and resistant Pseudomonas aeruginosa strains was studied. Strains becoming resistant to gentamicin either by laboratory training or through an R-factor were more susceptible to the phagocytic and bactericidal function of the PMNs. These results may explain previous clinical and laboratory observations indicating that gentamicin-resistant strains are less virulent.

In vitro activity of ticarcillin, carbenicillin and ampicillin against some gram-negative bacilli.

alpha-Carboxy-3-thienylmethyl penicillin (ticarcillin) is a relatively new semisynthetic penicillin which is more active than carbenillin against Pseudomonas aeruginosa. Among the strains tested, those isolated from the respiratory tract showed an increased susceptibility to carbenicillin and ticarcillin. As with carbenicillin, synergistic activity against P. aeruginosa could be demonstrated with ticarcillin in combination with gentamicin. Like other penicillins, the antibacterial activity was influenced by the inoculum size. The antibacterial activity of ticarcillin showed the compound to be almost equally active with carbenicillin and ampicillin against Escherichia coli and Klebsiella aerogenes, but less active than acrbenicillin and ampicillin against indole-negative Proteus strains. Regarding the indole-positive Proteus species, at relatively low antibiotic concentrations the proportion of strains sensitive to ticarcillin was greater than to carbenicillin or ampicillin whereas at relatively high antibiotic concentrations the converse was the case. It is interesting to note that a high proportion of strains of E. coli and K. aerogenes were resistant to the three penicillins even at a concentration of 200 mug/ml, while 70% of Proteus strains were inhibited by these drugs at the same concentration. Disc susceptibility tests with ticarcillin were carried out according to BAUER-KIRBY method.

In vivo potentiation of polymorphonuclear leukocyte function by ciprofloxacin.

Ciprofloxacin was administered to 10 healthy volunteers at a dose of 250 mg orally. Serum and polymorphonuclear leukocytes (PMNLs) were obtained from all subjects before the administration of the drug and 12 hours after the administration. In addition serum was obtained from all subjects at 24 and 48 hours after ciprofloxacin administration. All sera and PMNLs were used for the chemotactic, phagocytic and killing determinations of the PMNLs. The results demonstrated that serum obtained 12 hours after the administration of ciprofloxacin potentiates PMNL chemotactic activity (chemotactic index (CI) = 33.0 +/- 4.2 microns (means +/- S.D.)) as compared to the chemotactic activity generated by serum obtained prior to administration of the drug, CI = 20.4 +/- 4.4 microns (p < 0.01). Serum obtained 24 and 48 hours after ciprofloxacin administration did not stimulate PMNL function. The administration of ciprofloxacin did not have any direct influence on the PMNLs in terms of their chemotactic response. Furthermore, serum obtained after the administration of ciprofloxacin markedly enhanced PMNL phagocytosis and killing of all organisms tested. Ciprofloxacin also acted directly on the PMNLs and increased their bactericidal activity. These results demonstrate that ciprofloxacin potentiates PMNL function in vivo which may be of potential clinical benefit.

Effects of methylprednisolone and dexamethasone on polymorphonuclear leukocyte adherence in vivo.

It has been proposed that corticosteroids may be effective in the treatment of shock and the adult respiratory distress syndrome (ARDS) by inhibiting complement-induced granulocyte aggregation and by disaggregating granulocyte aggregates in vitro. In the present investigation we have examined the effects of sera from patients who had received comparable doses of methylprednisolone (MP) and dexamethasone (DEX) on the adherence of polymorphonuclear leukocytes (PMNs). Sera obtained from patients that had received MP markedly reduced PMN adherence with maximum effect noted by 8 h. In contrast, sera from patients receiving DEX had no effect on PMN adherence. The results of this study indicate that MP may be more effective in the treatment of septic shock and other conditions associated with microvascular leukostasis.

Adherence of Candida albicans to epithelial cells from normal and cancerous urinary bladders.

Patients with malignancies are at high risk to develop infections by Candida albicans. We have compared the adherence of C. albicans isolated from urine cultures to bladder epithelial cells obtained from healthy volunteers and patients with cancer of the bladder. The mean number of C. albicans adhering per epithelial cell from areas infiltrated from cancer was significantly higher as compared to cells obtained from intact areas of cancerous bladders and from normal bladders. The increased adherence of C. albicans to cancerous epithelial cells suggests that malignancies are associated with alterations of the epithelial cell surface which render the cells more susceptible to colonization by C. albicans. The increased colonization may predispose these patients to C. albicans infections.

[Evaluation of the efficacy of antimicrobial drugs in ophthalmic solutions]. / Evaluation de l'efficacité des agents antimicrobiens dans les solutions ophtalmiques.

The antimicrobial efficacy of preservatives in ophthalmic solutions was tested. Five strains were used as challenge organisms. They represented bacteria, yeasts and molds. Sixty per cent of the ophthalmic solutions showed a good preservation against S. aureus ATCC 6538, according to the standards and in 40% of cases, the bacteria disappeared on the second week. Against E. coli ATCC 8739, 90% of the samples were well preserved and in 10% the bacteria disappeared by the second week. Against Ps. aeruginosa ATCC 9027, C. Albicans ATCC 10231 and Asp. niger ATCC 16404, the ophthalmic solutions showed a 100% preservation. The majority of the products showed a satisfactory preservation. They contained declared preservatives and sometimes combinations of two antimicrobial agents.

The influence of carbohydrate-containing media on some biological properties of Staphylococcus aureus.

After growth of S. aureus strains on glucose medium all the colonies obtained were negative for coagulase production. About half of the colonies grown on mannitol or maltose media were coagulase negative. Thermostable-nuclease and hemolysin activity were not affected by the carbohydrate media.

Survival of bacteriophage 1 of the Salmonella typhimurium phage typing scheme in 4 different types of sterile soil.

The survival of bacteriophage 1 of the Salmonella typhimurium phage typing scheme was studied in four different types of sterile soil at 4.20 and 37 degrees C. The longevity of the phage was generally short, not exceeding 36 days and depended on the temperature and the type of soil.