Search for composite and exotic fermions at LEP 2

A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio

Search for charginos in e+e- interactions at sqrt(s) = 189 GeV

An update of the searches for charginos and gravitinos is presented, based on a data sample corresponding to the 158 pb^{-1} recorded by the DELPHI detector in 1998, at a centre-of-mass energy of 189 GeV. No evidence for a signal was found. The lower mass limits are 4-5 GeV/c^2 higher than those obtained at a centre-of-mass energy of 183 GeV. The (\mu,M_2) MSSM domain excluded by combining the chargino searches with neutralino searches at the Z resonance implies a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 31.0 GeV/c^2 for tan(beta) \geq 1.Comment: 22 pages, 8 figure

Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP

Promptly decaying lightest neutralinos and long-lived staus are searched for in the context of light gravitino scenarios. It is assumed that the stau is the next to lightest supersymmetric particle (NLSP) and that the lightest neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of the production of these particles is found. Hence, lower mass limits for both kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is found to be greater than 71.5 GeV/c^2. In the search for long-lived stau, masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10 to 150 \eVcc . Combining this search with the searches for stable heavy leptons and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc may be set for the stau mas

Hadronization properties of b quarks compared to light quarks in e+e- -> q qbar from 183 to 200 GeV

The DELPHI detector at LEP has collected 54 pb^{-1} of data at a centre-of-mass energy around 183 GeV during 1997, 158 pb^{-1} around 189 GeV during 1998, and 187 pb^{-1} between 192 and 200 GeV during 1999. These data were used to measure the average charged particle multiplicity in e+e- -> b bbar events, _{bb}, and the difference delta_{bl} between _{bb} and the multiplicity, _{ll}, in generic light quark (u,d,s) events: delta_{bl}(183 GeV) = 4.55 +/- 1.31 (stat) +/- 0.73 (syst) delta_{bl}(189 GeV) = 4.43 +/- 0.85 (stat) +/- 0.61 (syst) delta_{bl}(200 GeV) = 3.39 +/- 0.89 (stat) +/- 1.01 (syst). This result is consistent with QCD predictions, while it is inconsistent with calculations assuming that the multiplicity accompanying the decay of a heavy quark is independent of the mass of the quark itself.Comment: 13 pages, 2 figure

National identity predicts public health support during a global pandemic

Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = −0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics.publishedVersio

Microbial Influence on Arsenic Speciation: In Search of the Origins of Arsenic Resistance

Early life on Earth had to cope with heat, acidity and high dissolved metal(loid) concentrations. Arsenic (As) is one metalloid enriched in geothermal waters. In order to survive toxic arsenic levels, microorganisms developed arsenic resistance mechanisms for arsenic species present at that time. Modern hot springs provide an analog to early Earth conditions in terms of temperature and dissolved arsenic concentrations. The nucleic acid data suggest a hyperthermophilic root of life, which supports the hypothesis of hot springs providing ideal conditions to investigate the evolution of microbial arsenic resistance. Geothermal pools in Wai-O-Tapu, New Zealand, with different temperature, pH and redox condition were studied for their arsenic speciation and microbial diversity. On an Eh-pH diagram, all pools plotted within the arsenite (H 3AsO 3) stability field. Alongside arsenite, however, HPLC-ICPMS analyses also detected arsenate, organic arsenic and unknown arsenic species, suggesting active microbial transformation of As[III] via one or more arsenic resistance mechanisms

Thio arsenic species measurements in marine organisms and geothermal waters

Recently two new classes of arsenic species have been identified, thio-methylated arsenic species in marine organisms where the oxygen bonded to arsenic is replaced by an S group and thioarsenate species in sulfide rich water environments. Here we describe the use of HPLC-ICPMS to measure thio arsenic species found in marine biota and a geothermal water sample from a sulfide rich environment. Thio-methylated arsenic species were separated using an Alantis C18 reverse phase column and elution with an aqueous 20 mM phosphate buffer (pH3). Thioarsenate species were separated using an Ion Pac, AS16 anion exchange column with a sodium hydroxide gradient (20–100 mM) and the use of an anionic self-regenerating suppressor to remove sodium ions before the ICPMS spray chamber. Thio-methylated arsenic species in marine biota are stable to freeze drying and microwave extraction with methanol–water (1:1 v/v) at 70 °C. Rotational mixing at 25 °C for long periods causes the loss of species. Freeze–thawing of extracts results in oxidation of species. Thio-methylated arsenic species in extracts are stable if the solvent is removed and the residues stored dry in a dessicator. Thioarsenate species in water samples are stable during analysis if manipulated under a nitrogen atmosphere and if during chromatography mobile phases are degassed and precautions taken to exclude air from samples

Microbial Influence on Arsenic Speciation: In Search of the Origins of Arsenic Resistance

Early life on Earth had to cope with heat, acidity and high dissolved metal(loid) concentrations. Arsenic (As) is one metalloid enriched in geothermal waters. In order to survive toxic arsenic levels, microorganisms developed arsenic resistance mechanisms for arsenic species present at that time. Modern hot springs provide an analog to early Earth conditions in terms of temperature and dissolved arsenic concentrations. The nucleic acid data suggest a hyperthermophilic root of life, which supports the hypothesis of hot springs providing ideal conditions to investigate the evolution of microbial arsenic resistance. Geothermal pools in Wai-O-Tapu, New Zealand, with different temperature, pH and redox condition were studied for their arsenic speciation and microbial diversity. On an Eh-pH diagram, all pools plotted within the arsenite (H 3AsO 3) stability field. Alongside arsenite, however, HPLC-ICPMS analyses also detected arsenate, organic arsenic and unknown arsenic species, suggesting active microbial transformation of As[III] via one or more arsenic resistance mechanisms