Prehabilitation bundle can reduce incidence of postoperative pulmonary complications

INTRODUCTION

Elective major colorectal surgery is still associated with postoperative morbidity and mortality. Preoperative optimization can potentially reduce postoperative pulmonary complications, which significantly prolong recovery and increase the risk of mortality. The aim of this study was to evaluate the effect of the prehabilitation bundle on postoperative pulmonary complications.

METHODS

All patients undergoing elective colorectal procedure for benign or malignant diagnosis before and after the introduction of the prehabilitation bundle were enrolled in the study. Prehabilitation was focused on nutritional support, regular aerobic and muscle strength exercise, preoperative optimization of anaemia, improvement of oral hygiene including regular chlorhexidine mouth wash, psychological support, restriction of smoking and alcohol consumption. In addition to the general characteristics, compliance with individual measures, incidence of pulmonary complications and length of stay were monitored.

RESULTS

A total of 596 patients were included in the study (226 before and 370 after the implementation of the package). After the introduction of prehabilitation, the incidence of postoperative pulmonary complications decreased significantly - 29 (13%) vs. 17 (4.6%), RR: 0.21-0.67), p=0.001 and shorter length of stay was observed à 9.7 (±8.8) to 7.7 (±5.5) days (p=0.0005). Except for optimization of anaemia, compliance with the individual components of the established bundle was very good.

CONCLUSION

Introduction of a prehabilitation bundle focused on improvement of cardiorespiratory capacity, optimization of diet and oral hygiene, can reduce the risk of postoperative pulmonary complications and shorten the length of stay.

OP0220 CRITERIA ASSOCIATED WITH TREATMENT DECISIONS IN JUVENILE IDIOPATHIC ARTHRITIS WITH A FOCUS ON ULTRASONOGRAPHY: RESULTS FROM THE JIRECHO COHORT

Background

Treatment of children with juvenile idiopathic arthritis (JIA) is a major challenge in paediatric rheumatology. The presence of synovitis, which is difficult to detect in children, is associated with structural damage. Musculoskeletal ultrasonography (MSUS) can be used in JIA patients to reveal subclinical synovitis.

Objectives

Our aim was to determine if the use of MSUS is associated with therapeutic modifications in JIA. Secondary outcomes were to identify other factors associated with therapeutic modifications.

Methods

We conducted an observational study based on the JIRECHO multicentre cohort which was developed to provide a systematic MSUS follow-up for JIA patients. Follow-up occurred every six months and included clinical and US examinations. We included children who underwent MSUS of the elbows, wrists, second metacarpophalangeal joints, knees and ankles. Synovitis in US was defined by the presence of joint effusion and/or synovial hypertrophy in B-mode (≥ grade 1) associated or not with Doppler signals (≥ grade 1). US was performed by expert sonographers with good experience in the field of JIA who previously participated in the study of the reliability of the OMERACT paediatric US synovitis definitions and scoring system in JIA (1). Clinical and biological data, disease activity score and information on therapeutics were collected.

Results

We included 112 patients with 185 visits in total. Three groups of patients were defined according to their therapeutic status: increased(22%), decreased(14%) or stable(64%) treatment. First, we compared patients with treatment escalation with the other patients. Patients with “increased treatment” had more synovitis in B-mode US than the other patients (80% vs. 65%, p=0.06). There was no difference for the presence of synovitis in Power Doppler (PD) US (30% vs 23%, p=0.4). Patient’s and physician’s visual analogue scale (VAS) scores were significantly higher in patients with therapeutic escalation [3.3 vs 1.7, p<0.01 and 3.6 vs 1.6, p<0.0001] as well as disease activity score and inflammatory biological markers. Then, we compared patients with therapeutic de-escalation with the other patients. There was no difference in the presence of synovitis in US when compared with patients with stable treatment (62% vs. 69%, p=0.5) but there was less synovitis in B-mode ≥ grade 2 (8% vs. 24%, p=0.05).

We performed ROC curves analysis that showed that the sensitivity and specificity of the US in B-mode was similar to the physician’s VAS, disease score activity or inflammatory biological markers (Figure 1).

Figure 1.

ROC curves for clinical and biological items and US in B-mode in patients with « therapeutic escalation »

Conclusion

In our study, MSUS of ten joints was not statistically associated with treatment escalation or de-escalation in B-mode and PD in patients with JIA.

References

[1]Rossi-Semerano, L. et al. Application of the OMERACT synovitis ultrasound scoring system in juvenile idiopathic arthritis: a multicenter reliability exercise. Rheumatol. Oxf. Engl. (2020) doi:10.1093/rheumatology/keaa804.

Disclosure of Interests

None declared

POS0411 COMPARISON OF MTX-POLYGLUTAMATE ACCUMULATION PROFILES IN PERIPHERAL BLOOD MONONUCLEAR CELLS AND ERYTHROCYTES DURING 6 MONTHS MTX-THERAPY IN THE METHOTREXATE MONITORING (MeMo) TRIAL

Background

Optimal dosing of methotrexate (MTX) in rheumatoid arthritis (RA) remains challenging. To this end, monitoring of intracellular MTX polyglutamates (MTX-PGs) in red blood cells (RBCs) has been investigated as a potential marker of MTX (non-)response, with contradictory results. As enucleated, non-proliferative cells, mature RBCs lack regulated folate metabolism and are devoid of folylpolyglutamate synthetase (FPGS) activity catalyzing the conversion of MTX to MTX-PGs. Therefore, it has been argued that analysis of MTX-PG in immune-effector cells, represented by peripheral blood mononuclear cells (PBMCs), would be more relevant. However, no prospective study has been performed measuring MTX-PG levels in PBMCs nor in comparison with RBCs.

Objectives

To investigate the pharmacokinetics of MTX-PG accumulation in RBCs and PBMCs in newly diagnosed RA patients in the early phase of MTX treatment.

Methods

In a clinical prospective cohort study (Methotrexate Monitoring (NTR7149)), RA patients were administered MTX op to 25 mg/week, as described before. (1) At 1, 2, 3 and 6 months after start of therapy, blood was collected and RBCs were isolated by centrifugation and PBMCs after Ficoll density gradient centrifugation. MTX-PG1-6 concentrations in these cells were analyzed using a UPLC-MS/MS method with including custom-made stable isotopes of MTX-PG1-6 as internal standards. (2) UPLC-MS/MS measurements for MTX-PG1-6 were performed with a Waters Acquity BEH C18 column coupled to an AB Sciex 6500+ with the ESI operating on the positive mode. MTX dosing and concomitant treatments were in conformity with clinical practice. (3)

Results

46 consecutive patients were included in this study; 76% female, mean age: 57.8 years, mean baseline DAS28-ESR: 3.5, as described before. (1) Mean dosage was 10.5 mg (SD: 1.5) at baseline, 16.3 mg (2.5) at month 1, 22.7 mg (4.5) at month 2, 19.5 mg (6.3) at month 3 and 19.1 mg (6.2) at month 6.

MTX-PG accumulation in PBMCs and RBCs revealed a disparate profile in both MTX-PG distribution and absolute accumulation levels (Figure 1A/B). Remarkably, MTX-PG distribution in PBMCs was mainly composed of MTX-PG1 (58%), and to a lesser extent MTX-PG2 (27%) and MTX-PG3 (15%). Longer chain MTX-PG4-6 were also detectable in PBMCs, but at lower levels (mean: 4.0 – 6.7 fmol/10^6 cells) than MTX-PG1-3. Moreover, this MTX-PG distribution profile in PBMCs remained constant over a MTX therapy period of 6 months (Figure 1A). The RBC MTX-PG accumulation profile shows mainly MTX-PG1 and lower levels of MTX-PG2-6 at 1 month after the start of therapy. After 3 months of therapy, MTX-PG3 is the main PG-moiety with also MTX-PG4,5,6 being detected. This profile is largely similar after 6 months of therapy. With respect to total intracellular MTX-PG1-6 accumulation, PBMCs had significantly (p<0.001) 10-20-fold higher levels than RBCs at all analyzed time points (Figure 1A/B). Total MTX-PG1-6 levels in RBCs and PBMCs at all time points were weakly correlated (r=0.41, p<0.01) (Figure 1C).

Figure 1.

Individual MTX-PG concentrations in PBMCs (A) and RBCs (B) during the first 6 months of MTX administration (note the different scaling of the y-axes). At 6 months, 36 patients were still on MTX treatment. Panel (C): Spearman’s correlation plot of total MTX-PGs in RBCs versus PBMCs of all time points.

The disparate MTX-PG accumulation and distribution profiles in PBMCs versus RBCs of RA patients may be associated with the shorter life span of PBMCs and the low FPGS activity in RBCs. (4)

No significant relation between MTX-PGs and DAS28 was found (data not shown).

Conclusion

This study shows that in newly diagnosed RA patients starting MTX therapy, MTX-PG concentrations in PBMCs are significantly 10-20-fold higher than in RBCs over a period of 6 months, with a disparate MTX-PG distribution profile in PBMCs (highest: MTX-PG1) than RBCs (highest: MTX-PG3).

References

[1]RCF Hebing, Arthr Rheum (2021)

[2]E den Boer, Anal Bioanal Chem (2013)

[3]J Smolen, Ann Rheum Dis (2020)

[4]IB Muller, Ther Drug Monit (2019)

Acknowledgements

Acknowledgements: We would like to thank all participating patients and Pfizer (grant 53233663 / WI230458), AmsterdamUMC (AI&II extension grant) and NVKC (Noyons grant 2018)

Disclosure of Interests

Renske Hebing Grant/research support from: Pfizer (grant 53233663 / WI230458), NVKC (Netherlands Society for Clinical Chemistry, Noyons grant 2018) and AmsterdamUMC (extension grant), Marry Lin: None declared, Eduard Struys: None declared, Sohaila Mahmoud: None declared, Ittai Muller: None declared, Sandra Heil: None declared, Pieter Griffioen: None declared, WIllem Lems: None declared, Bart van den Bemt Speakers bureau: Pfizer, UCB, Sanofi-Aventis, Galapagos, Amgen and Eli Lilly, Michael Nurmohamed Grant/research support from: Pfizer grant 53233663 / WI230458, Gerrit Jansen: None declared, Robert De Jonge Grant/research support from: NVKC (Netherlands Society for Clinical Chemistry, Noyons grant)

AB0061 PHARMACOKINETICS OF METHOTREXATE POLYGLUTAMATES IN PERIPHERAL BLOOD MONONUCLEAR CELLS OF RA PATIENTS IS SIMILAR AFTER SUBCUTANEOUS OR ORAL ADMINISTRATION IN THE METHOTREXATE MONITORING (MeMo) TRIAL

Background

Pharmacokinetics of methotrexate (MTX) after oral and subcutaneous administration to RA patients differs: MTX levels in plasma and MTX-polyglutamate (MTX-PG) accumulation in erythrocytes are higher during equidosed subcutaneous compared to oral MTX treatment. (1,2) No data are available whether administration route of MTX differentially impacts the intracellular concentrations of MTX-PGs in peripheral blood mononuclear cells (PBMCs) during MTX therapy.

Objectives

To investigate the pharmacokinetics of MTX-PGs in PBMCs of newly diagnosed RA patients receiving oral or subcutaneous MTX in the early phase (1, 2, 3 and 6 months) of MTX treatment.

Methods

In a clinical prospective cohort study (MeMo study (NTR7149)), RA patients were

administered oral (n=24) or subcutaneous (n=22) MTX up to 25 mg MTX/week, as described before. (1) At 1, 2, 3 and 6 months after the start of therapy, PBMCs were isolated via Ficoll density gradient centrifugation. Individual MTX-PG forms (MTX-PG1-6) in PBMCs were analyzed by a UPLC-MS/MS method including custom-made stable isotopes of MTX-PG1-6 as internal standards (3). UPLC-MS/MS measurements of the PBMCs were performed with a Waters Acquity BEH C18 column coupled to an AB Sciex 6500+ with the ESI operating on the positive mode. Dosing, concomitant treatments and DAS28-ESR assessments were in conformity with clinical practice. (4)

Results

46 consecutive patients were included in this study; 76% female, mean age: 57.8 years, BMI: 25.8, smokers: 20%, mean baseline DAS28-ESR: 3.5, as described before. (1) MTX dose at baseline was 10.5 mg (SD: 1.5) for both groups, 15.4 mg (4.4) and 16.8 mg (1.8) at 1 month, 22.8 mg (3.9) and 22.4 mg (5.2) at 2 months, 20.1 mg (6.3) and 20.8 mg (5.6) at 3 months, and 19.7 mg (6.1) and 18.5 mg (6.7) at 6 months for oral and subcutaneous use, respectively. MTX-PG analyses in PBMCs for individual and total MTX-PGs revealed no significant differences between oral and subcutaneous administration groups at 1, 2, 3, and 6 months (Figure 1). Linear regression of LN transformed MTX-PG levels in PBMCs and administration route, corrected for age, baseline DAS28, smoking, BMI, eGFR and MTX dose, showed a trend towards higher MTX-PG levels in PBMCs after subcutaneous MTX administration compared to oral administration (data not shown). MTX-PG distribution in PBMCs was mainly composed of MTX-PG1 (58%), and to a lesser extent MTX-PG2 (27%) and MTX-PG3 (15%). Longer chain MTX-PGs beyond MTX-PG4 were detectable in PBMCs, but at levels lower than MTX-PG1-3 (mean: 4.0 – 6.7 fmol/106 cells). Total MTX-PG accumulation in PBMCs was approximately 10-20 fold higher than in erythrocytes. PBMC accumulation was rather stable, whereas RBC MTX-PG accumulation increased between 1 to 3 months to reach a plateau (Figure 1).

Figure 1.

Loess regression of MTX-PG concentrations in PBMCs (MTX-PG1-3) and RBCs (MTX-PG1-6) of RA patients during the first 6 months of oral or subcutaneous MTX administration. At 6 months, 18 patients using oral and 18 patients using subcutaneous MTX were still continuing MTX treatment. Means (lines) and SE (grey areas) are depicted.

Conclusion

This study demonstrated that MTX-PG accumulation in PBMCs early on in the MTX treatment of RA patients was not significantly different between oral or subcutaneous MTX administration routes.

References

[1]RCF Hebing et al, Arthritis Rheum (2021); 60:339-348

[2]M Hoekstra et al, J Rheumatol (2004); 31:645-8

[3]E Den Boer et al, Anal Bioanal Chem (2013); 405: 1673-1681

[4]J Smolen et al, Ann Rheum Dis (2020); 79:685-699

Acknowledgements

We would like to thank all participating patients and Pfizer (grant 53233663 / WI230458), NVKC (Noyons grant) and AmsterdamUMC (AI&II extension grant).

Disclosure of Interests

Renske Hebing Grant/research support from: Pfizer, grant number 53233663 / WI230458, Amsterdam UMC (AI&II extension grant), NVKC (Netherlands Society for Clinical Chemistry, Noyons grant), Marry Lin: None declared, Eduard Struys: None declared, Sohaila Mahmoud: None declared, Ittai Muller: None declared, WIllem Lems: None declared, Bart van den Bemt Speakers bureau: Pfizer, UCB, Sanofi-Aventis, Galapagos, Amgen and Eli Lilly, Gerrit Jansen: None declared, Robert De Jonge Grant/research support from: NVKC (Netherlands Society for Clinical Chemistry, Noyons grant), Michael Nurmohamed Grant/research support from: Pfizer grant

AB0251 INCREASED ACCUMULATION OF ERYTHROCYTE METHOTREXATE POLYGLUTAMATES DURING EARLY PHASE SUBCUTANEOUS VERSUS ORAL METHOTREXATE TREATMENT OF RHEUMATOID ARTHRITIS PATIENTS

Background:

Optimal dosing of methotrexate (MTX) for individual rheumatoid arthritis (RA) patients to achieve adequate disease control is an ongoing challenge. Assessment of erythrocyte MTX-polyglutamates (PGs) levels has been employed as a tool to monitor clinical response of RA patients in the first 3-12 months of treatment and MTX-PG2-4 and total MTX-PGs were associated with a lower DAS28 over 9 months.1 However, data from earlier time points, MTX-PG6 and per route of administration are unavailable.

Objectives:

To investigate the pharmacokinetics and -dynamics of erythrocyte MTX-PG accumulation in RA patients receiving oral or subcutaneous MTX in the early phase (1, 2, and 3 months) of MTX treatment initiation.

Methods:

In a clinical prospective cohort study (MeMo study (NTR7149)), newly diagnosed RA patients were administered oral (n=24) or subcutaneous (n=22) MTX, mostly according to the COBRA-light schedule (start 10 mg MTX, increased to 25 mg MTX in 8 weeks). At 1, 2, and 3 months after start of therapy, blood was collected and individual MTX-PGs (MTX-PG1 – MTX-PG6) were analyzed in erythrocytes at a minimal detection limit of 1 nmol/L, using a validated UHPLC-MS/MS method with labeled internal standards.1 Dosing, concomitant treatments and DAS28-ESR assessments were in conformity with clinical practice. Adverse events were recorded.

Results:

46 consecutive patients were included in this study; 76% female, mean age: 57.8 years, BMI: 25.8, 20% smokers, mean baseline DAS28-ESR: 3.5. Notwithstanding marked interpatient variability, patients starting subcutaneous MTX had accumulated significantly higher (approximately 2-fold) long chain MTX-PGs (MTX-PG4-6) when compared to patients in the oral MTX group at 1 and 2 months (Figure 1A, Table 1). Similarly, MTX-PG1-6 and MTX-PG3 accumulation were higher in subcutaneous MTX-users at month 1 (p=0.022 and p=0.011) compared to the oral group (median 68.6 nmol/L (IQR:40.5) vs 51.9 (55.6) and 17.4 (11.1) vs 11.2 (15.6), respectively (Figure 1B, Table 1).

Table 1.

Linear regression of MTX-PG levels and administration route, corrected for age, baseline DAS28, smoking, BMI, eGFR and MTX dose.

monthß (P-value)1ß (P-value)2ß (P-value)3MTX-PG1-61.65 (0.022)1.51 (0.073)1.30 (0.233)MTX-PG1,21.13 (0.599)1.19 (0.470)1.12 (0.623)MTX-PG31.75 (0.011)1.51 (0.071)1.19 (0.439)MTX-PG4-61.97 (0.036)2.04 (0.033)1.55 (0.136)

Mean MTX dose at baseline was 10.5mg (SD 1.5) for both groups, 15.4 (4.4) and 16.8 (1.8) at 1 month and 22.8 (3.9) and 22.4 (5.2) at 2 months for oral and subcutaneous use respectively.

DAS28 decreased with 1.6 in the oral group and 1.1 in the subcutaneous group (p=0.382). With and without corrections for age, baseline DAS28, eGFR, MTX dose (1 month before sampling), smoking and BMI, no significant relation between MTX-PG concentrations and DAS28 was observed during the first 3 months of treatment.

43 patients reported any side effect, mostly headache and dizziness, which was similar in both groups and uncorrelated with MTX-PG levels.

No association was found between MTX-PG1 levels and number of days between timing of blood withdrawal and last administration.

Figure 1.

Erythrocyte long chain MTX-PG(A) and total MTX-PG(B) accumulation in RA patients of the first 3 months of oral(C) or subcutaneous(D) MTX administration. At 3 months, 18 patients using oral and 18 patients using subcutaneous MTX were still continuing MTX treatment. Medians and IQR are depicted.

Conclusion:

This study shows the feasibility of measuring erythrocyte MTX-PGs early on in the treatment of RA patients with MTX and demonstrated significantly higher accumulation of MTX-PGs following subcutaneous versus oral MTX administration. Early phase erythrocyte MTX-PG analyses may hold potential for positioning in optimizing individual patient MTX dose scheduling.

References:

[1]de Rotte MC, et al. Methotrexate polyglutamates in erythrocytes are associated with lower disease activity in patients with rheumatoid arthritis. Ann Rheum Dis 2015(74):408-14.

Acknowledgements:

We would like to thank all participating patients and Pfizer (grant 53233663 / WI230458).

Disclosure of Interests:

Renske Hebing Grant/research support from: Pfizer, Ittai Muller: None declared, Marry Lin: None declared, Sohaila Mahmoud: None declared, Sandra Heil: None declared, WIllem Lems: None declared, Michael Nurmohamed: None declared, Robert De Jonge: None declared, Gerrit Jansen: None declared

The "Golden Hours" Algorithm For the Management of the Multisystem Inflammatory Syndrome in Children (MIS-C)

The global concern of increasing number of children presenting with multisystem inflammatory syndrome in children (MIS-C) related to the coronavirus disease (COVID-19) has escalated the need for a case-oriented clinical approach that provides timely diagnosis and management. The aim of this study is to share our experience in managing 64 MIS-C patients of North African ethnicity guided by a risk-based algorithm. Sixty-four patients met the inclusion criteria, 19 (30%) patients were categorized as mild and moderate risk groups and cared for in an isolation ward and 45 patients who belonged to the high-risk group (70%) were admitted to the pediatric intensive care unit (PICU). Positive laboratory evidence of COVID-19 was found in 62 patients. Fever and dysfunction in 2 or more organs were confirmed in all cases (100%). Fifty patients (78%) presented with gastrointestinal symptoms, meanwhile only 10 patients (16%) had respiratory manifestations. Cardiac involvement was reported in 55 (86%) cases; hypotension and shock were found in 45 patients (70%) therein circulatory support and mechanical ventilations were needed for 45 and 13 patients respectively. Intravenous immunoglobulins (IVIG) were used for all cases and methylprednisolone was used in 60 patients (94%). Fifty-eight (91%) patients were discharged home after an average of 9 days of hospitalization. The mortality rate was 9% (6 patients). Conclusion. A single Egyptian center experience in the management of MIS-C patients guided by a proposed bed side algorithm is described. The algorithm proved to be a helpful tool for first-line responders, and helped initiate early treatment with IVIG.

Thumb Polydactyly with Symphalangism

Three cases of thumb polydactyly in which one of the components demonstrates symphalangism are reported. This is a very rare anomaly and only one similar case could be found in the literature. The rarity of this anomaly was explained by the occurrence of two different abnormal molecular events along two different limb growth axes. Finally, the anomaly does not fit into the classification systems described for thumb polydactyly.

Measurement of the centrality dependence of the charged-particle pseudorapidity distribution in proton-lead collisions at [Formula: see text] TeV with the ATLAS detector

The centrality dependence of the mean charged-particle multiplicity as a function of pseudorapidity is measured in approximately 1 [Formula: see text]b[Formula: see text] of proton-lead collisions at a nucleon-nucleon centre-of-mass energy of [Formula: see text] [Formula: see text] using the ATLAS detector at the Large Hadron Collider. Charged particles with absolute pseudorapidity less than 2.7 are reconstructed using the ATLAS pixel detector. The [Formula: see text] collision centrality is characterised by the total transverse energy measured in the Pb-going direction of the forward calorimeter. The charged-particle pseudorapidity distributions are found to vary strongly with centrality, with an increasing asymmetry between the proton-going and Pb-going directions as the collisions become more central. Three different estimations of the number of nucleons participating in the [Formula: see text] collision have been carried out using the Glauber model as well as two Glauber-Gribov inspired extensions to the Glauber model. Charged-particle multiplicities per participant pair are found to vary differently for these three models, highlighting the importance of including colour fluctuations in nucleon-nucleon collisions in the modelling of the initial state of [Formula: see text] collisions.

Two-particle Bose-Einstein correlations in pp collisions at [Formula: see text] 0.9 and 7 TeV measured with the ATLAS detector

The paper presents studies of Bose-Einstein Correlations (BEC) for pairs of like-sign charged particles measured in the kinematic range [Formula: see text] 100 MeV and [Formula: see text] 2.5 in proton collisions at centre-of-mass energies of 0.9 and 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. The integrated luminosities are approximately 7 [Formula: see text]b[Formula: see text], 190 [Formula: see text]b[Formula: see text] and 12.4 nb[Formula: see text] for 0.9 TeV, 7 TeV minimum-bias and 7 TeV high-multiplicity data samples, respectively. The multiplicity dependence of the BEC parameters characterizing the correlation strength and the correlation source size are investigated for charged-particle multiplicities of up to 240. A saturation effect in the multiplicity dependence of the correlation source size parameter is observed using the high-multiplicity 7 TeV data sample. The dependence of the BEC parameters on the average transverse momentum of the particle pair is also investigated.

Evidence of Wγγ Production in pp Collisions at sqrt[s]=8 TeV and Limits on Anomalous Quartic Gauge Couplings with the ATLAS Detector

This Letter reports evidence of triple gauge boson production pp→W(ℓν)γγ+X, which is accessible for the first time with the 8 TeV LHC data set. The fiducial cross section for this process is measured in a data sample corresponding to an integrated luminosity of 20.3  fb^{-1}, collected by the ATLAS detector in 2012. Events are selected using the W boson decay to eν or μν as well as requiring two isolated photons. The measured cross section is used to set limits on anomalous quartic gauge couplings in the high diphoton mass region.

Identification and energy calibration of hadronically decaying tau leptons with the ATLAS experiment in pp collisions at [Formula: see text][Formula: see text]

This paper describes the trigger and offline reconstruction, identification and energy calibration algorithms for hadronic decays of tau leptons employed for the data collected from pp collisions in 2012 with the ATLAS detector at the LHC center-of-mass energy [Formula: see text] [Formula: see text]. The performance of these algorithms is measured in most cases with [Formula: see text] decays to tau leptons using the full 2012 dataset, corresponding to an integrated luminosity of 20.3 fb[Formula: see text]. An uncertainty on the offline reconstructed tau energy scale of 2-4 %, depending on transverse energy and pseudorapidity, is achieved using two independent methods. The offline tau identification efficiency is measured with a precision of 2.5 % for hadronically decaying tau leptons with one associated track, and of 4 % for the case of three associated tracks, inclusive in pseudorapidity and for a visible transverse energy greater than 20 [Formula: see text]. For hadronic tau lepton decays selected by offline algorithms, the tau trigger identification efficiency is measured with a precision of 2-8 %, depending on the transverse energy. The performance of the tau algorithms, both offline and at the trigger level, is found to be stable with respect to the number of concurrent proton-proton interactions and has supported a variety of physics results using hadronically decaying tau leptons at ATLAS.

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at [Formula: see text]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[Formula: see text] of [Formula: see text] TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with [Formula: see text] GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between [Formula: see text] GeV and [Formula: see text] 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 presented.

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at [Formula: see text]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[Formula: see text] of [Formula: see text] TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with [Formula: see text] GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between [Formula: see text] GeV and [Formula: see text] 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 presented.

Observation and measurements of the production of prompt and non-prompt [Formula: see text] mesons in association with a [Formula: see text] boson in [Formula: see text] collisions at [Formula: see text] with the ATLAS detector

The production of a [Formula: see text] boson in association with a [Formula: see text] meson in proton-proton collisions probes the production mechanisms of quarkonium and heavy flavour in association with vector bosons, and allows studies of multiple parton scattering. Using [Formula: see text] of data collected with the ATLAS experiment at the LHC in [Formula: see text] collisions at [Formula: see text], the first measurement of associated [Formula: see text] production is presented for both prompt and non-prompt [Formula: see text] production, with both signatures having a significance in excess of [Formula: see text]. The inclusive production cross-sections for [Formula: see text] boson production (analysed in [Formula: see text] or [Formula: see text] decay modes) in association with prompt and non-prompt [Formula: see text] are measured relative to the inclusive production rate of [Formula: see text] bosons in the same fiducial volume to be [Formula: see text] and [Formula: see text] respectively. Normalised differential production cross-section ratios are also determined as a function of the [Formula: see text] transverse momentum. The fraction of signal events arising from single and double parton scattering is estimated, and a lower limit of [Formula: see text] at [Formula: see text] confidence level is placed on the effective cross-section regulating double parton interactions.

Measurement of three-jet production cross-sections in [Formula: see text] collisions at 7 [Formula: see text] centre-of-mass energy using the ATLAS detector

Double-differential three-jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of [Formula: see text] using the ATLAS detector at the large hadron collider. The measurements are presented as a function of the three-jet mass [Formula: see text], in bins of the sum of the absolute rapidity separations between the three leading jets [Formula: see text]. Invariant masses extending up to 5  TeV are reached for [Formula: see text]. These measurements use a sample of data recorded using the ATLAS detector in 2011, which corresponds to an integrated luminosity of [Formula: see text]. Jets are identified using the anti-[Formula: see text] algorithm with two different jet radius parameters, [Formula: see text] and [Formula: see text]. The dominant uncertainty in these measurements comes from the jet energy scale. Next-to-leading-order QCD calculations corrected to account for non-perturbative effects are compared to the measurements. Good agreement is found between the data and the theoretical predictions based on most of the available sets of parton distribution functions, over the full kinematic range, covering almost seven orders of magnitude in the measured cross-section values.

Search for production of [Formula: see text] resonances decaying to a lepton, neutrino and jets in [Formula: see text] collisions at [Formula: see text] TeV with the ATLAS detector

A search is presented for narrow diboson resonances decaying to [Formula: see text] or [Formula: see text] in the final state where one [Formula: see text] boson decays leptonically (to an electron or a muon plus a neutrino) and the other [Formula: see text] boson decays hadronically. The analysis is performed using an integrated luminosity of 20.3 fb[Formula: see text] of [Formula: see text] collisions at [Formula: see text] TeV collected by the ATLAS detector at the large hadron collider. No evidence for resonant diboson production is observed, and resonance masses below 700 and 1490 GeV are excluded at 95 % confidence level for the spin-2 Randall-Sundrum bulk graviton [Formula: see text] with coupling constant of 1.0 and the extended gauge model [Formula: see text] boson respectively.

Search for direct pair production of a chargino and a neutralino decaying to the 125 GeV Higgs boson in [Formula: see text] TeV [Formula: see text] collisions with the ATLAS detector

A search is presented for the direct pair production of a chargino and a neutralino [Formula: see text], where the chargino decays to the lightest neutralino and the [Formula: see text] boson, [Formula: see text], while the neutralino decays to the lightest neutralino and the 125 GeV Higgs boson, [Formula: see text]. The final states considered for the search have large missing transverse momentum, an isolated electron or muon, and one of the following: either two jets identified as originating from bottom quarks, or two photons, or a second electron or muon with the same electric charge. The analysis is based on 20.3 [Formula: see text] of [Formula: see text] proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with the Standard Model expectations, and limits are set in the context of a simplified supersymmetric model.

Search for production of [Formula: see text] resonances decaying to a lepton, neutrino and jets in [Formula: see text] collisions at [Formula: see text] TeV with the ATLAS detector

A search is presented for narrow diboson resonances decaying to [Formula: see text] or [Formula: see text] in the final state where one [Formula: see text] boson decays leptonically (to an electron or a muon plus a neutrino) and the other [Formula: see text] boson decays hadronically. The analysis is performed using an integrated luminosity of 20.3 fb[Formula: see text] of [Formula: see text] collisions at [Formula: see text] TeV collected by the ATLAS detector at the large hadron collider. No evidence for resonant diboson production is observed, and resonance masses below 700 and 1490 GeV are excluded at 95 % confidence level for the spin-2 Randall-Sundrum bulk graviton [Formula: see text] with coupling constant of 1.0 and the extended gauge model [Formula: see text] boson respectively.

Search for Scalar Charm Quark Pair Production in pp Collisions at sqrt[s]=8 TeV with the ATLAS Detector

The results of a dedicated search for pair production of scalar partners of charm quarks are reported. The search is based on an integrated luminosity of 20.3  fb^{-1} of pp collisions at sqrt[s]=8  TeV recorded with the ATLAS detector at the LHC. The search is performed using events with large missing transverse momentum and at least two jets, where the two leading jets are each tagged as originating from c quarks. Events containing isolated electrons or muons are vetoed. In an R-parity-conserving minimal supersymmetric scenario in which a single scalar-charm state is kinematically accessible, and where it decays exclusively into a charm quark and a neutralino, 95% confidence-level upper limits are obtained in the scalar-charm-neutralino mass plane such that, for neutralino masses below 200 GeV, scalar-charm masses up to 490 GeV are excluded.

Search for [Formula: see text] decays in [Formula: see text] collisions at [Formula: see text] = 8 TeV with the ATLAS detector

A search for a massive [Formula: see text] gauge boson decaying to a top quark and a bottom quark is performed with the ATLAS detector in [Formula: see text] collisions at the LHC. The dataset was taken at a centre-of-mass energy of [Formula: see text] and corresponds to [Formula: see text] of integrated luminosity. This analysis is done in the hadronic decay mode of the top quark, where novel jet substructure techniques are used to identify jets from high-momentum top quarks. This allows for a search for high-mass [Formula: see text] bosons in the range 1.5-3.0 [Formula: see text]. [Formula: see text]-tagging is used to identify jets originating from [Formula: see text]-quarks. The data are consistent with Standard Model background-only expectations, and upper limits at 95 % confidence level are set on the [Formula: see text] cross section times branching ratio ranging from [Formula: see text] to [Formula: see text] for left-handed [Formula: see text] bosons, and ranging from [Formula: see text] to [Formula: see text] for [Formula: see text] bosons with purely right-handed couplings. Upper limits at 95 % confidence level are set on the [Formula: see text]-boson coupling to [Formula: see text] as a function of the [Formula: see text] mass using an effective field theory approach, which is independent of details of particular models predicting a [Formula: see text] boson.

Measurement of the top-quark mass in the fully hadronic decay channel from ATLAS data at [Formula: see text]

The mass of the top quark is measured in a data set corresponding to 4.6 [Formula: see text] of proton-proton collisions with centre-of-mass energy [Formula: see text] TeV collected by the ATLAS detector at the LHC. Events consistent with hadronic decays of top-antitop quark pairs with at least six jets in the final state are selected. The substantial background from multijet production is modelled with data-driven methods that utilise the number of identified [Formula: see text]-quark jets and the transverse momentum of the sixth leading jet, which have minimal correlation. The top-quark mass is obtained from template fits to the ratio of three-jet to dijet mass. The three-jet mass is calculated from the three jets produced in a top-quark decay. Using these three jets the dijet mass is obtained from the two jets produced in the [Formula: see text] boson decay. The top-quark mass obtained from this fit is thus less sensitive to the uncertainty in the energy measurement of the jets. A binned likelihood fit yields a top-quark mass of [Formula: see text].

Measurement of spin correlation in top-antitop quark events and search for top squark pair production in pp collisions at √s=8 TeV using the ATLAS detector

A measurement of spin correlation in tt[over ¯] production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3  fb^{-1}. The correlation between the top and antitop quark spins is extracted from dilepton tt[over ¯] events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to A_{helicity}=0.38±0.04, in agreement with the standard model prediction. A search is performed for pair production of top squarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.

Search for Higgs and Z Boson Decays to J/ψγ and ϒ(nS)γ with the ATLAS Detector

A search for the decays of the Higgs and Z bosons to J/ψγ and ϒ(nS)γ (n=1,2,3) is performed with pp collision data samples corresponding to integrated luminosities of up to 20.3  fb^{-1} collected at sqrt[s]=8  TeV with the ATLAS detector at the CERN Large Hadron Collider. No significant excess of events is observed above expected backgrounds and 95% C.L. upper limits are placed on the branching fractions. In the J/ψγ final state the limits are 1.5×10^{-3} and 2.6×10^{-6} for the Higgs and Z boson decays, respectively, while in the ϒ(1S,2S,3S)γ final states the limits are (1.3,1.9,1.3)×10^{-3} and (3.4,6.5,5.4)×10^{-6}, respectively.

Performance of the ATLAS muon trigger in pp collisions at [Formula: see text] TeV

The performance of the ATLAS muon trigger system is evaluated with proton-proton collision data collected in 2012 at the Large Hadron Collider at a centre-of-mass energy of 8 TeV. It is primarily evaluated using events containing a pair of muons from the decay of [Formula: see text] bosons. The efficiency of the single-muon trigger is measured for muons with transverse momentum [Formula: see text] GeV, with a statistical uncertainty of less than 0.01 % and a systematic uncertainty of 0.6 %. The [Formula: see text] range for efficiency determination is extended by using muons from decays of [Formula: see text] mesons, [Formula: see text] bosons, and top quarks. The muon trigger shows highly uniform and stable performance. The performance is compared to the prediction of a detailed simulation.

Search for Higgs boson pair production in the γγbb[over ¯] final state using pp collision data at sqrt[s]=8 TeV from the ATLAS detector

Searches are performed for resonant and nonresonant Higgs boson pair production in the γγbb[over ¯] final state using 20  fb^{-1} of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider. A 95% confidence level upper limit on the cross section times branching ratio of nonresonant production is set at 2.2 pb, while the expected limit is 1.0 pb. The difference derives from a modest excess of events, corresponding to 2.4 standard deviations from the background-only hypothesis. The limit observed in the search for a narrow X→hh resonance ranges between 0.7 and 3.5 pb as a function of the resonance mass.

Search for dark matter in events with heavy quarks and missing transverse momentum in [Formula: see text] collisions with the ATLAS detector

This article reports on a search for dark matter pair production in association with bottom or top quarks in [Formula: see text] of [Formula: see text] collisions collected at [Formula: see text] TeV by the ATLAS detector at the LHC. Events with large missing transverse momentum are selected when produced in association with high-momentum jets of which one or more are identified as jets containing [Formula: see text]-quarks. Final states with top quarks are selected by requiring a high jet multiplicity and in some cases a single lepton. The data are found to be consistent with the Standard Model expectations and limits are set on the mass scale of effective field theories that describe scalar and tensor interactions between dark matter and Standard Model particles. Limits on the dark-matter-nucleon cross-section for spin-independent and spin-dependent interactions are also provided. These limits are particularly strong for low-mass dark matter. Using a simplified model, constraints are set on the mass of dark matter and of a coloured mediator suitable to explain a possible signal of annihilating dark matter.

Measurements of the Nuclear Modification Factor for Jets in Pb+Pb Collisions at √(s)NN]=2.76 TeV with the ATLAS detector

Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at √(s)NN=2.76  TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14  nb(-1), respectively. The jets are identified with the anti-k(t) algorithm with R=0.4, and the spectra are measured over the kinematic range of jet transverse momentum 32<p(T)<500  GeV and absolute rapidity |y|<2.1 and as a function of collision centrality. The nuclear modification factor R(AA) is evaluated, and jets are found to be suppressed by approximately a factor of 2 in central collisions compared to pp collisions. The R(AA) shows a slight increase with p(T) and no significant variation with rapidity.

Measurements of the [Formula: see text] production cross sections in association with jets with the ATLAS detector

This paper presents cross sections for the production of a [Formula: see text] boson in association with jets, measured in proton-proton collisions at [Formula: see text] with the ATLAS experiment at the large hadron collider. With an integrated luminosity of [Formula: see text], this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentum of [Formula: see text] and multiplicities up to seven associated jets. The production cross sections for [Formula: see text] bosons are measured in both the electron and muon decay channels. Differential cross sections for many observables are also presented including measurements of the jet observables such as the rapidities and the transverse momenta as well as measurements of event observables such as the scalar sums of the transverse momenta of the jets. The measurements are compared to numerous QCD predictions including next-to-leading-order perturbative calculations, resummation calculations and Monte Carlo generators.

Search for invisible particles produced in association with single-top-quarks in proton-proton collisions at [Formula: see text] with the ATLAS detector

A search for the production of single-top-quarks in association with missing energy is performed in proton-proton collisions at a centre-of-mass energy of [Formula: see text] with the ATLAS experiment at the large hadron collider using data collected in 2012, corresponding to an integrated luminosity of [Formula: see text] fb[Formula: see text]. In this search, the [Formula: see text] boson from the top quark is required to decay into an electron or a muon and a neutrino. No deviation from the standard model prediction is observed, and upper limits are set on the production cross-section for resonant and non-resonant production of an invisible exotic state in association with a right-handed top quark. In the case of resonant production, for a spin-[Formula: see text] resonance with a mass of [Formula: see text] GeV, an effective coupling strength above [Formula: see text] is excluded at 95[Formula: see text] confidence level for the top quark and an invisible spin-[Formula: see text] state with mass between [Formula: see text] and [Formula: see text] GeV. In the case of non-resonant production, an effective coupling strength above [Formula: see text] is excluded at 95[Formula: see text] confidence level for the top quark and an invisible spin-[Formula: see text] state with mass between [Formula: see text] and [Formula: see text] GeV.

Search for resonant diboson production in the [Formula: see text] final state in [Formula: see text] collisions at [Formula: see text] TeV with the ATLAS detector

This paper reports on a search for narrow resonances in diboson production in the [Formula: see text] final state using [Formula: see text] collision data corresponding to an integrated luminosity of [Formula: see text] fb[Formula: see text] collected at [Formula: see text] TeV with the ATLAS detector at the Large Hadron Collider. No significant excess of data events over the Standard Model expectation is observed. Upper limits at the 95 % confidence level are set on the production cross section times branching ratio for Kaluza-Klein gravitons predicted by the Randall-Sundrum model and for Extended Gauge Model [Formula: see text] bosons. These results lead to the exclusion of mass values below 740 and 1590 GeV for the graviton and [Formula: see text] boson respectively.

Measurement of the production and lepton charge asymmetry of [Formula: see text] bosons in Pb+Pb collisions at [Formula: see text] with the ATLAS detector

A measurement of [Formula: see text] boson production in lead-lead collisions at [Formula: see text] is presented. It is based on the analysis of data collected with the ATLAS detector at the LHC in 2011 corresponding to an integrated luminosity of 0.14 [Formula: see text] and 0.15 [Formula: see text] in the muon and electron decay channels, respectively. The differential production yields and lepton charge asymmetry are each measured as a function of the average number of participating nucleons [Formula: see text] and absolute pseudorapidity of the charged lepton. The results are compared to predictions based on next-to-leading-order QCD calculations. These measurements are, in principle, sensitive to possible nuclear modifications to the parton distribution functions and also provide information on scaling of [Formula: see text] boson production in multi-nucleon systems.

Jet energy measurement and its systematic uncertainty in proton-proton collisions at [Formula: see text] TeV with the ATLAS detector

The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector using proton-proton collision data with a centre-of-mass energy of [Formula: see text] TeV corresponding to an integrated luminosity of [Formula: see text][Formula: see text]. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells using the anti-[Formula: see text] algorithm with distance parameters [Formula: see text] or [Formula: see text], and are calibrated using MC simulations. A residual JES correction is applied to account for differences between data and MC simulations. This correction and its systematic uncertainty are estimated using a combination of in situ techniques exploiting the transverse momentum balance between a jet and a reference object such as a photon or a [Formula: see text] boson, for [Formula: see text] and pseudorapidities [Formula: see text]. The effect of multiple proton-proton interactions is corrected for, and an uncertainty is evaluated using in situ techniques. The smallest JES uncertainty of less than 1 % is found in the central calorimeter region ([Formula: see text]) for jets with [Formula: see text]. For central jets at lower [Formula: see text], the uncertainty is about 3 %. A consistent JES estimate is found using measurements of the calorimeter response of single hadrons in proton-proton collisions and test-beam data, which also provide the estimate for [Formula: see text] TeV. The calibration of forward jets is derived from dijet [Formula: see text] balance measurements. The resulting uncertainty reaches its largest value of 6 % for low-[Formula: see text] jets at [Formula: see text]. Additional JES uncertainties due to specific event topologies, such as close-by jets or selections of event samples with an enhanced content of jets originating from light quarks or gluons, are also discussed. The magnitude of these uncertainties depends on the event sample used in a given physics analysis, but typically amounts to 0.5-3 %.