M, Membranes, and OM

We examine the extent to which the action for the membrane of M-theory (the eleven-dimensional construct which underlies and unifies all of the known string theories) simplifies in the so-called Open Membrane (OM) limit, a limit which lies at the root of the various manifestations of noncommutativity in the string context. In order for the discussion to be relatively self-contained, we start out by reviewing why the strings of ten-dimensional string theory are in fact membranes (M2-branes) living in eleven dimensions. After that, we recall the definition of OM theory, as well as the arguments showing that it is part of a larger, eleven-dimensional structure known as Galilean or Wrapped M2-brane (WM2) theory. WM2 theory is a rich theoretical construct which is interesting for several reasons, in particular because it is essentially a toy model of M-theory. We then proceed to deduce a membrane action for OM/WM2 theory, and spell out its implications for the four different types of M2-branes one can consider in this setting. For two of these types, the action in question can be simplified by gauge-fixing to a form which implies a discrete membrane spectrum. The boundary conditions for the remaining two cases do not allow this same gauge choice, and so their dynamics remain to be unraveled.Comment: LaTeX 2e, 8 pages; aimed at phenomenologists. Invited talk given by A. Guijosa at the X Mexican School of Particles and Fields, Playa del Carmen, Mexico, November 200

Treatment of combined atlantoaxial fractures in the elderly with C1-C2 posterior screw-rod instrumentation

Introducción: Dado que la instrumentación posterior tornillo-barra C1-C2 ha demostrado tener buenos resultados postoperatorios en diferentes tipos de patologías con inestabilidad atlantoaxial independiente de la edad, es razonable pensar en su potencial aplicabilidad en el escenario de las fracturas atlantoaxiales combinadas en pacientes adultos mayores, para quienes el manejo quirúrgico ha demostrado ser beneficioso. Objetivo: Realizar una descripción retrospectiva de los resultados postoperatorios obtenidos en pacientes adultos mayores con fracturas atlantoaxiales combinadas llevados a manejo quirúrgico con instrumentación posterior tornillo-barra C1-C2. Materiales y Métodos: Se realizó revisión de las historias clínicas de pacientes mayores de 65 años admitidos a dos hospitales de la ciudad de Bogotá DC entre enero de 2016 hasta enero de 2017, diagnosticados con fracturas traumáticas agudas combinadas del atlas y del axis y llevados a instrumentación posterior C1-C2 con constructos tornillo-barra. De la historia clínica se tomaron datos demográficos, clínicos, tipos de fractura, estado neurológico, estado de dolor, estado de fusión ósea, entre otros. Resultados: Se obtuvieron siete pacientes masculinos, con edad promedio 72,3 años. Ninguno presentó complicaciones perioperatorias o deterioro neurológico postoperatorio. Se evidenció fusión ósea y estabilidad del constructo en el 100% de los pacientes al año postoperatorio, con resolución completa del dolor cervical en 5 individuos, y parcial en los dos restantes. Conclusiones: La instrumentación posterior con constructos tornillo-barra C1-C2 es una excelente opción para el manejo quirúrgico de pacientes adultos mayores con fracturas atlantoaxiales combinadas dada su baja tasa de complicaciones y alta tasa de fusión ósea.Introduction: Since C1-C2 posterior screw-rod instrumentation has shown good postoperative results in different types of pathologies with atlantoaxial instability independent of age, it is reasonable to think about its potential applicability in the scenario of combined atlantoaxial fractures in elderly patients, for whom surgical management has proven beneficial. Objective: To perform a retrospective description of the postoperative results obtained in elderly patients with combined atlantoaxial fractures brought to surgical management with C1-C2 posterior screw-rod instrumentation. Materials and Methods: Medical records of patients older than 65 years admitted to two hospitals in the city of Bogotá DC from January 2016 to January 2017, diagnosed with combined acute traumatic fractures of the atlas and the axis, taken to later C1-C2 posterior screw-rod instrumentation were reviewed. Demographic and clinical data, type of fractures, neurological status, pain status, bone fusion status, among others, were collected. Results: Seven male patients were obtained, with an average age of 72.3 years. None presented perioperative complications or postoperative neurological deterioration. Bone fusion and stability of the construct were evidenced in 100% of the patients a year after surgery, with complete resolution of cervical pain in 5 individuals, and partial resolution in the remaining two. Conclusions: C1-C2 posterior screw-rod instrumentation is an excellent option for the surgical management of elderly patients with combined atlantoaxial fractures given its low rate of complications and high rate of bone fusion

Spectroscopic Characterization of Galaxy Clusters in RCS-1: Spectroscopic Confirmation, Redshift Accuracy, and Dynamical Mass–Richness Relation

We present follow-up spectroscopic observations of galaxy clusters from the first Red-sequence Cluster Survey (RCS-1). This work focuses on two samples, a lower redshift sample of ∼30 clusters ranging in redshift from z ∼ 0.2–0.6 observed with multiobject spectroscopy (MOS) on 4–6.5-m class telescopes and a z ∼ 1 sample of ∼10 clusters 8-m class telescope observations. We examine the detection efficiency and redshift accuracy of the now widely used red-sequence technique for selecting clusters via overdensities of red-sequence galaxies. Using both these data and extended samples including previously published RCS-1 spectroscopy and spectroscopic redshifts from SDSS, we find that the red-sequence redshift using simple two-filter cluster photometric redshifts is accurate to σz ≈ 0.035(1 + z) in RCS-1. This accuracy can potentially be improved with better survey photometric calibration. For the lower redshift sample, ∼5 per cent of clusters show some (minor) contamination from secondary systems with the same red-sequence intruding into the measurement aperture of the original cluster. At z ∼ 1, the rate rises to ∼20 per cent. Approximately ten  per cent of projections are expected to be serious, where the two components contribute significant numbers of their red-sequence galaxies to another cluster. Finally, we present a preliminary study of the mass–richness calibration using velocity dispersions to probe the dynamical masses of the clusters. We find a relation broadly consistent with that seen in the local universe from the WINGS sample at z ∼ 0.05

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV