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  1. Md Rezal RS, Hassali MA, Saleem F, Kumar R
    Value Health, 2015 Nov;18(7):A848-9.
    PMID: 26534536 DOI: 10.1016/j.jval.2015.09.420
    Conference abstrract
    Objectives: Antimicrobial resistance is associated with irrational use of antibiotics in general practice. We aimed to assess the frequency with which patients with Upper Respiratory Tract Infections were prescribed with antibiotics and the patterns of antibiotic prescription at primary healthcare centres in Malaysia.
    Methods: The study targeted all primary public healthcare centres in the district of Kota Setar, Kedah, Malaysia. A retrospective prescription analysis was conducted whereby prescriptions from 1st January 2014 to 31st March 2014 were screened and retrieved for antibiotics prescribed for upper respiratory infections. The data was entered into Microsoft Excel spread sheet, and exported to Statistical Package for Social Sciences, version 20 for further analysis. Frequencies and percentages were used to summarize the data. The Jonckheere–Terpstra test was used to evaluate the trend of antibiotic prescription. Where significant associations were reported, effect size was calculated by using Kendall tau correlation coefficient. P value of <0.05 was considered to be of statistical significance.
    Results: For the period of three months, 123,524 prescriptions were screened and analysed. 2270 (31.8%) prescriptions contained antibiotics prescribed for all URTIs visits. Among all antibiotics, macrolides were the most commonly prescribed antibiotic, constituting of 61% (n=1404) of total antibiotics prescribed for all cases. The Jonckheere–Terpstra test revealed a statistical relationship between prescribers and the diagnosis of the disease (p=0·001). Furthermore, a weak positive trend of association was reported with FMS being more accurate in diagnosis followed by MOs and AMOs (τ=0·122).
    Conclusions: Practicing physicians should adhere to the standard treatment practices, as antibiotic use in viral aetiology is ineffective, and encourages the persistence development of resistance. A comprehensive development of national antibiotic stewardship program is recommended to ensure organised and regulated control of antibiotic use in Malaysia.
  2. Tan BY, Shafie AA, Hassali MA, Saleem F, Kumar R
    Value Health, 2015 Nov;18(7):A831.
    PMID: 26534439 DOI: 10.1016/j.jval.2015.09.317
    Objectives: Medication adherence to treatment recommendations has major impact on health outcomes. Numerous interventions to improve medication adherence among the patients have been studied in clinical trials, including calendar packaging and patient reminder letters. Therefore, this study is aimed to explore hypertensive patient’s perceptions towards calendar packaging and its impact on medication adherence.
    Methods: A qualitative method was adopted, whereby two focus group sessions were conducted among 16 conveniently sampled hypertensive patients from a community based non-governmental organisation in the state of Penang, Malaysia. A pre validated focus group guide was constructed and used for data collection. Collected data was transcribed verbatim and analysed by thematic content analysis to identify the emerging themes.
    Results: Each focus group consisted of 8 hypertensive patients. Thematic content analysis resulted into 3 major themes (knowledge and familiarity with the medicines names and their packaging; perception about the packaging and labelling of medicines; knowledge and views of calendar packaging) and each theme was further divided into 2 sub themes. Majority of the hypertensive patients were not familiar with their medication names, however they were able to identify their medications based on the appearance and packaging. Participants agreed that calendar packaging is a great intervention to increase awareness among patients about regular medicine use and increase medication adherence.
    Conclusions: The study concluded that hypertensive patients relied on the packaging and labelling on the medications to identify their medications. Thus, packaging and labelling of the medications play an important role in improving medication adherence and reduce medication errors. This finding can help to enhance the drug manufacturers to pay attention on the drug packaging in order to increase medication adherence among the patients.
  3. Chow CK, Ramasundarahettige C, Hu W, AlHabib KF, Avezum A, Cheng X, et al.
    Lancet Diabetes Endocrinol, 2018 10;6(10):798-808.
    PMID: 30170949 DOI: 10.1016/S2213-8587(18)30233-X
    BACKGROUND: Data are scarce on the availability and affordability of essential medicines for diabetes. Our aim was to examine the availability and affordability of metformin, sulfonylureas, and insulin across multiple regions of the world and explore the effect of these on medicine use.

    METHODS: In the Prospective Urban Rural Epidemiology (PURE) study, participants aged 35-70 years (n=156 625) were recruited from 110 803 households, in 604 communities and 22 countries; availability (presence of any dose of medication in the pharmacy on the day of audit) and medicine cost data were collected from pharmacies with the Environmental Profile of a Community's Health audit tool. Our primary analysis was to describe the availability and affordability of metformin and insulin and also commonly used and prescribed combinations of two medicines for diabetes management (two oral drugs, metformin plus a sulphonylurea [either glibenclamide (also known as glyburide) or gliclazide] and one oral drug plus insulin [metformin plus insulin]). Medicines were defined as affordable if the cost of medicines was less than 20% of capacity-to-pay (the household income minus food expenditure). Our analyses included data collected in pharmacies and data from representative samples of households. Data on availability were ascertained during the pharmacy audit, as were data on cost of medications. These cost data were used to estimate the cost of a month's supply of essential medicines for diabetes. We estimated affordability of medicines using income data from household surveys.

    FINDINGS: Metformin was available in 113 (100%) of 113 pharmacies from high-income countries, 112 (88·2%) of 127 pharmacies in upper-middle-income countries, 179 (86·1%) of 208 pharmacies in lower-middle-income countries, 44 (64·7%) of 68 pharmacies in low-income countries (excluding India), and 88 (100%) of 88 pharmacies in India. Insulin was available in 106 (93·8%) pharmacies in high-income countries, 51 (40·2%) pharmacies in upper-middle-income countries, 61 (29·3%) pharmacies in lower-middle-income countries, seven (10·3%) pharmacies in lower-income countries, and 67 (76·1%) of 88 pharmacies in India. We estimated 0·7% of households in high-income countries and 26·9% of households in low-income countries could not afford metformin and 2·8% of households in high-income countries and 63·0% of households in low-income countries could not afford insulin. Among the 13 569 (8·6% of PURE participants) that reported a diagnosis of diabetes, 1222 (74·0%) participants reported diabetes medicine use in high-income countries compared with 143 (29·6%) participants in low-income countries. In multilevel models, availability and affordability were significantly associated with use of diabetes medicines.

    INTERPRETATION: Availability and affordability of essential diabetes medicines are poor in low-income and middle-income countries. Awareness of these global differences might importantly drive change in access for patients with diabetes.

    FUNDING: Full funding sources listed at the end of the paper (see Acknowledgments).

  4. Mente A, Dehghan M, Rangarajan S, McQueen M, Dagenais G, Wielgosz A, et al.
    Lancet Diabetes Endocrinol, 2017 10;5(10):774-787.
    PMID: 28864143 DOI: 10.1016/S2213-8587(17)30283-8
    BACKGROUND: The relation between dietary nutrients and cardiovascular disease risk markers in many regions worldwide is unknown. In this study, we investigated the effect of dietary nutrients on blood lipids and blood pressure, two of the most important risk factors for cardiovascular disease, in low-income, middle-income, and high-income countries.

    METHODS: We studied 125 287 participants from 18 countries in North America, South America, Europe, Africa, and Asia in the Prospective Urban Rural Epidemiology (PURE) study. Habitual food intake was measured with validated food frequency questionnaires. We assessed the associations between nutrients (total fats, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, carbohydrates, protein, and dietary cholesterol) and cardiovascular disease risk markers using multilevel modelling. The effect of isocaloric replacement of saturated fatty acids with other fats and carbohydrates was determined overall and by levels of intakes by use of nutrient density models. We did simulation modelling in which we assumed that the effects of saturated fatty acids on cardiovascular disease events was solely related to their association through an individual risk marker, and then compared these simulated risk marker-based estimates with directly observed associations of saturated fatty acids with cardiovascular disease events.

    FINDINGS: Participants were enrolled into the study from Jan 1, 2003, to March 31, 2013. Intake of total fat and each type of fat was associated with higher concentrations of total cholesterol and LDL cholesterol, but also with higher HDL cholesterol and apolipoprotein A1 (ApoA1), and lower triglycerides, ratio of total cholesterol to HDL cholesterol, ratio of triglycerides to HDL cholesterol, and ratio of apolipoprotein B (ApoB) to ApoA1 (all ptrend<0·0001). Higher carbohydrate intake was associated with lower total cholesterol, LDL cholesterol, and ApoB, but also with lower HDL cholesterol and ApoA1, and higher triglycerides, ratio of total cholesterol to HDL cholesterol, ratio of triglycerides to HDL cholesterol, and ApoB-to-ApoA1 ratio (all ptrend<0·0001, apart from ApoB [ptrend=0·0014]). Higher intakes of total fat, saturated fatty acids, and carbohydrates were associated with higher blood pressure, whereas higher protein intake was associated with lower blood pressure. Replacement of saturated fatty acids with carbohydrates was associated with the most adverse effects on lipids, whereas replacement of saturated fatty acids with unsaturated fats improved some risk markers (LDL cholesterol and blood pressure), but seemed to worsen others (HDL cholesterol and triglycerides). The observed associations between saturated fatty acids and cardiovascular disease events were approximated by the simulated associations mediated through the effects on the ApoB-to-ApoA1 ratio, but not with other lipid markers including LDL cholesterol.

    INTERPRETATION: Our data are at odds with current recommendations to reduce total fat and saturated fats. Reducing saturated fatty acid intake and replacing it with carbohydrate has an adverse effect on blood lipids. Substituting saturated fatty acids with unsaturated fats might improve some risk markers, but might worsen others. Simulations suggest that ApoB-to-ApoA1 ratio probably provides the best overall indication of the effect of saturated fatty acids on cardiovascular disease risk among the markers tested. Focusing on a single lipid marker such as LDL cholesterol alone does not capture the net clinical effects of nutrients on cardiovascular risk.

    FUNDING: Full funding sources listed at the end of the paper (see Acknowledgments).

  5. Kumar R, Htwe O, Baharudin A, Rhani SA, Ibrahim K, Nanra JS, et al.
    J Spinal Cord Med, 2023 Jul;46(4):682-686.
    PMID: 35604343 DOI: 10.1080/10790268.2022.2067972
    OBJECTIVE: MLC601/MLC901 has demonstrated neuroprotective and neuroregenerative properties that enhance neurological recovery in stroke and traumatic brain injury. We aimed to evaluate its safety and potential efficacy in patients with severe spinal cord injury.

    METHODS: Patients with American Spinal Injury Association (ASIA) Impairment Scale (AIS) A and B were included in an open-label cohort study. Each received a course of MLC601/MLC901 for 6 months in addition to standard care and rehabilitation. Key endpoints were safety, AIS grade and motor scores at month 6 (M6).

    RESULTS: Among 30 patients included (mean age 42.2 ± 17.6 years, 24 men), 20 patients had AIS A while 10 patients had AIS B at baseline. Ten patients experienced 14 adverse events including one serious adverse event and six deaths, none were considered treatment-related. AIS improved in 25% of AIS A and 50% of AIS B. Improvement in ASIA motor score was seen most with cervical injury (median change from baseline 26.5, IQR: 6-55). These findings appear to be better than reported rates of spontaneous recovery for SCI AIS A and B.

    CONCLUSION: MLC601/MLC901 is safe and may have a role in the treatment of patients with SCI. A controlled trial is justified.

  6. Gujjar KR, van Wijk A, Kumar R, de Jongh A
    J Evid Based Dent Pract, 2019 06;19(2):140-155.
    PMID: 31326046 DOI: 10.1016/j.jebdp.2019.01.009
    OBJECTIVES: The aim of this study was to evaluate the effectiveness of technology-based interventions for the treatment of dental anxiety in children and adults.

    DATA SOURCES: A systematic search using relevant keywords was conducted in PubMed-Medline, EMBASE, PsycINFO, CINAHL, Scopus, and The Cochrane Library.

    INCLUSION CRITERIA: Randomized controlled trials (RCTs) that compared technology-based interventions with inactive controls in the treatment of moderate to severe dental anxiety were included.

    RESULTS: A total of seven RCTs were included in the review. These studies investigated the effectiveness of video modeling, computerized cognitive behavioral therapy, virtual reality exposure therapy, and distraction with music and audiovisual video material. Six studies examining video modeling, computerized cognitive behavioral therapy, virtual reality exposure therapy, and distraction (audiovisual) showed significantly greater reductions in dental anxiety than inactive controls in both children and adults. None of the included studies followed Consolidated Standards of Reporting Trials guidelines completely or reported sufficient data, thereby precluding a possible meta-analysis. Four out of seven included studies were assessed to be at high risk of bias.

    CONCLUSIONS: A limited number of studies supported the effectiveness of technology-based interventions in the treatment of dental anxiety in children and adults.

    CLINICAL SIGNIFICANCE: The quality of the methods of studies on the effects of technology-based interventions allows only limited inferences on the effects of these interventions. However, within the limitations of the systematic review, the results converge to suggest that technology-based interventions may be useful as an adjunct to standard dental care. High-quality RCTs are needed to determine the (relative) effectiveness of these interventions.

    PROSPERO REGISTRATION NUMBER: CRD42017064810.

  7. Yusuf S, Rangarajan S, Teo K, Islam S, Li W, Liu L, et al.
    N Engl J Med, 2014 08 28;371(9):818-27.
    PMID: 25162888 DOI: 10.1056/NEJMoa1311890
    BACKGROUND: More than 80% of deaths from cardiovascular disease are estimated to occur in low-income and middle-income countries, but the reasons are unknown.
    METHODS: We enrolled 156,424 persons from 628 urban and rural communities in 17 countries (3 high-income, 10 middle-income, and 4 low-income countries) and assessed their cardiovascular risk using the INTERHEART Risk Score, a validated score for quantifying risk-factor burden without the use of laboratory testing (with higher scores indicating greater risk-factor burden). Participants were followed for incident cardiovascular disease and death for a mean of 4.1 years.
    RESULTS: The mean INTERHEART Risk Score was highest in high-income countries, intermediate in middle-income countries, and lowest in low-income countries (P<0.001). However, the rates of major cardiovascular events (death from cardiovascular causes, myocardial infarction, stroke, or heart failure) were lower in high-income countries than in middle- and low-income countries (3.99 events per 1000 person-years vs. 5.38 and 6.43 events per 1000 person-years, respectively; P<0.001). Case fatality rates were also lowest in high-income countries (6.5%, 15.9%, and 17.3% in high-, middle-, and low-income countries, respectively; P=0.01). Urban communities had a higher risk-factor burden than rural communities but lower rates of cardiovascular events (4.83 vs. 6.25 events per 1000 person-years, P<0.001) and case fatality rates (13.52% vs. 17.25%, P<0.001). The use of preventive medications and revascularization procedures was significantly more common in high-income countries than in middle- or low-income countries (P<0.001).
    CONCLUSIONS: Although the risk-factor burden was lowest in low-income countries, the rates of major cardiovascular disease and death were substantially higher in low-income countries than in high-income countries. The high burden of risk factors in high-income countries may have been mitigated by better control of risk factors and more frequent use of proven pharmacologic therapies and revascularization. (Funded by the Population Health Research Institute and others.).
    Note: Malaysia is a study site (Author: Yusoff K)
  8. Peffault de Latour R, Röth A, Kulasekararaj AG, Han B, Scheinberg P, Maciejewski JP, et al.
    N Engl J Med, 2024 Mar 14;390(11):994-1008.
    PMID: 38477987 DOI: 10.1056/NEJMoa2308695
    BACKGROUND: Persistent hemolytic anemia and a lack of oral treatments are challenges for patients with paroxysmal nocturnal hemoglobinuria who have received anti-C5 therapy or have not received complement inhibitors. Iptacopan, a first-in-class oral factor B inhibitor, has been shown to improve hemoglobin levels in these patients.

    METHODS: In two phase 3 trials, we assessed iptacopan monotherapy over a 24-week period in patients with hemoglobin levels of less than 10 g per deciliter. In the first, anti-C5-treated patients were randomly assigned to switch to iptacopan or to continue anti-C5 therapy. In the second, single-group trial, patients who had not received complement inhibitors and who had lactate dehydrogenase (LDH) levels more than 1.5 times the upper limit of the normal range received iptacopan. The two primary end points in the first trial were an increase in the hemoglobin level of at least 2 g per deciliter from baseline and a hemoglobin level of at least 12 g per deciliter, each without red-cell transfusion; the primary end point for the second trial was an increase in hemoglobin level of at least 2 g per deciliter from baseline without red-cell transfusion.

    RESULTS: In the first trial, 51 of the 60 patients who received iptacopan had an increase in the hemoglobin level of at least 2 g per deciliter from baseline, and 42 had a hemoglobin level of at least 12 g per deciliter, each without transfusion; none of the 35 anti-C5-treated patients attained the end-point levels. In the second trial, 31 of 33 patients had an increase in the hemoglobin level of at least 2 g per deciliter from baseline without red-cell transfusion. In the first trial, 59 of the 62 patients who received iptacopan and 14 of the 35 anti-C5-treated patients did not require or receive transfusion; in the second trial, no patients required or received transfusion. Treatment with iptacopan increased hemoglobin levels, reduced fatigue, reduced reticulocyte and bilirubin levels, and resulted in mean LDH levels that were less than 1.5 times the upper limit of the normal range. Headache was the most frequent adverse event with iptacopan.

    CONCLUSIONS: Iptacopan treatment improved hematologic and clinical outcomes in anti-C5-treated patients with persistent anemia - in whom iptacopan showed superiority to anti-C5 therapy - and in patients who had not received complement inhibitors. (Funded by Novartis; APPLY-PNH ClinicalTrials.gov number, NCT04558918; APPOINT-PNH ClinicalTrials.gov number, NCT04820530.).

  9. Velmurugan C, Sundaram T, Sampath Kumar R, Vivek B, Sheshadrishekar D, Ashok Kumar BS
    Med J Malaysia, 2011 Mar;66(1):22-6.
    PMID: 23765138
    The hypoglycemic and hypolipidemic effect of Ethanolic extract of Ougeinia oojeinensis (200mg/kg) bark was evaluated with measurements including, Body weight, blood glucose level, urine glucose and biochemical parameters. The ethanolic extracts of the powdered bark was tested for its efficacy in alloxan-induced diabetic rats. Animals were induced for diabetes with Alloxan (150 mg/kg of body weight- i.p.) and treated orally with Ethanolic extract of Ougeinia oojeinensis. The extracts were also evaluated for acute oral toxicity studies and its effect on different biochemical parameters. The extracts showed significant (p<0.01) antihyperglycemic and hypolipidemic activity as compared to diabetic control. The extract shows beneficial effects on blood glucose and urine glucose level. It also reduces the elevated biochemical parameters such as triglycerides (TGL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), Total Cholesterol (TC) and increased the reduced level of high density lipoprotein (HDL) and body weight, which might be due to presence of steroids, tannins, alkaloids and triterpenoids present in that extract. Thus ethanolic extract could serve as good oral hypoglycemic agents and seems to be promising for the development of phytomedicines for diabetes mellitus.
  10. Segasothy M, Thyaparan A, Sivalingam S, Kamal A, Vijaya Kumar R
    Med J Malaysia, 1986 Mar;41(1):19-23.
    PMID: 3796342
    594 intravenous urograms done at the General Hospital, Ipoh, from January 1981 to March 1985 were reviewed for renal papillary necrosis (RPN). 11 cases (1.8%) of RPN were detected. Of these three were due to diabetes mellitus;eight were due to analgesic nephropathy. There was an equal incidence
    in males and females, contrary to the experience in the West and Australia. RPN was observed mainly in the older age groups. Five of the 11 cases of RPN presented as renal colic.
  11. Kumar D, Rishabh Kumar R, Kujur A, Kumar C, Sunderam S, Kashyap V, et al.
    Malays J Med Sci, 2020 Jul;27(4):108-118.
    PMID: 32863750 DOI: 10.21315/mjms2020.27.4.10
    Background: This study intends to find the growth patterns of selected school children. Globally accepted statistical methods were used to evaluate the data and prepare a growth chart.

    Methods: This cross-sectional study was conducted with school-going children from 16 selected schools of a tribal district in Jharkhand using multistage cluster random sampling. In each selected school, 60 students, 30 boys and 30 girls, were chosen randomly, totaling 960 children (full data was for 935 children only). Growth charts were created using Lambda-Mu-Sigma (LMS) chart maker version 2.5 for height, weight and body mass index (BMI). In the charts, the LMS values with Z scores for each age and respective height and weight for boys and girls were recorded.

    Results: The 468 boys and 467 girls were in the range of 6-14 years of age. Percentile values obtained for the measured heights in centimetres were evaluated and compared with Indian Academy of Pediatrics reference charts for boys and girls for the same age group, and our values were found to be on the lower side. We were able to plot a growth chart of the data set; as the tribal children's ethnicity is different, this growth chart might be used to assess nutritional status.

    Conclusion: We concluded that growth curves for height, weight, and BMI may be used for evaluating children of age 6-14 years in the tribal population. The measures can be a good indicator of their nourishment status and overall growth patterns, which might be indigenous to their ethnicity. A larger sample size of similar tribal populations may give a clearer picture.

  12. Duong M, Islam S, Rangarajan S, Leong D, Kurmi O, Teo K, et al.
    Lancet Glob Health, 2019 05;7(5):e613-e623.
    PMID: 31000131 DOI: 10.1016/S2214-109X(19)30070-1
    BACKGROUND: The associations between the extent of forced expiratory volume in 1 s (FEV1) impairment and mortality, incident cardiovascular disease, and respiratory hospitalisations are unclear, and how these associations might vary across populations is unknown.

    METHODS: In this international, community-based cohort study, we prospectively enrolled adults aged 35-70 years who had no intention of moving residences for 4 years from rural and urban communities across 17 countries. A portable spirometer was used to assess FEV1. FEV1 values were standardised within countries for height, age, and sex, and expressed as a percentage of the country-specific predicted FEV1 value (FEV1%). FEV1% was categorised as no impairment (FEV1% ≥0 SD from country-specific mean), mild impairment (FEV1% <0 SD to -1 SD), moderate impairment (FEV1%

  13. Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.
    Eur Phys J C Part Fields, 2017;77(12):845.
    PMID: 31985736 DOI: 10.1140/epjc/s10052-017-5317-4
    A search is presented for an excess of events with heavy-flavor quark pairs (

    t

    t
    ¯


    and

    b

    b
    ¯


    ) and a large imbalance in transverse momentum in data from proton-proton collisions at a center-of-mass energy of 13


    TeV

    . The data correspond to an integrated luminosity of 2.2



    fb

    -
    1



    collected with the CMS detector at the CERN LHC. No deviations are observed with respect to standard model predictions. The results are used in the first interpretation of dark matter production in

    t

    t
    ¯


    and

    b

    b
    ¯


    final states in a simplified model. This analysis is also the first to perform a statistical combination of searches for dark matter produced with different heavy-flavor final states. The combination provides exclusions that are stronger than those achieved with individual heavy-flavor final states.
  14. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(9):773.
    PMID: 31713548 DOI: 10.1140/epjc/s10052-019-7276-4
    A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, Δ ϕ 12 , is presented. The measurement considers events where the two leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of 13 Te and corresponding to an integrated luminosity of 35.9 fb - 1 are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region 177 ∘ < Δ ϕ 12 < 180 ∘ . The 2- and 3-jet measurements are not simultaneously described by any of models.
  15. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(2):140.
    PMID: 31265001 DOI: 10.1140/epjc/s10052-018-5607-5
    A search for standard model production of four top quarks ( t t ¯ t t ¯ ) is reported using events containing at least three leptons ( e , μ ) or a same-sign lepton pair. The events are produced in proton-proton collisions at a center-of-mass energy of 13 TeV at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9 fb - 1 . Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the t t ¯ t t ¯ cross section is measured to be 16 . 9 - 11.4 + 13.8 fb , in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level.
  16. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(4):291.
    PMID: 31007582 DOI: 10.1140/epjc/s10052-018-5740-1
    A search for new physics in events with a Z boson produced in association with large missing transverse momentum at the LHC is presented. The search is based on the 2016 data sample of proton-proton collisions recorded with the CMS experiment at s = 13 TeV , corresponding to an integrated luminosity of 35.9 fb - 1 . The results of this search are interpreted in terms of a simplified model of dark matter production via spin-0 or spin-1 mediators, a scenario with a standard-model-like Higgs boson produced in association with the Z boson and decaying invisibly, a model of unparticle production, and a model with large extra spatial dimensions. No significant deviations from the background expectations are found, and limits are set on relevant model parameters, significantly extending the results previously achieved in this channel.
  17. Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.
    Eur Phys J C Part Fields, 2018;78(3):242.
    PMID: 31264999 DOI: 10.1140/epjc/s10052-018-5691-6
    Events with no charged particles produced between the two leading jets are studied in proton-proton collisions at s = 7 TeV . The jets were required to have transverse momentum p T jet > 40 GeV and pseudorapidity 1.5 < | η jet | < 4.7 , and to have values of η jet with opposite signs. The data used for this study were collected with the CMS detector during low-luminosity running at the LHC, and correspond to an integrated luminosity of 8 pb - 1 . Events with no charged particles with p T > 0.2 GeV in the interval - 1 < η < 1 between the jets are observed in excess of calculations that assume no color-singlet exchange. The fraction of events with such a rapidity gap, amounting to 0.5-1% of the selected dijet sample, is measured as a function of the p T of the second-leading jet and of the rapidity separation between the jets. The data are compared to previous measurements at the Tevatron, and to perturbative quantum chromodynamics calculations based on the Balitsky-Fadin-Kuraev-Lipatov evolution equations, including different models of the non-perturbative gap survival probability.
  18. Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.
    Eur Phys J C Part Fields, 2017;77(11):746.
    PMID: 31999281 DOI: 10.1140/epjc/s10052-017-5286-7
    A measurement is presented of the triple-differential dijet cross section at a centre-of-mass energy of 8 TeV using 19.7 fb -1 of data collected with the CMS detector in proton-proton collisions at the LHC. The cross section is measured as a function of the average transverse momentum, half the rapidity separation, and the boost of the two leading jets in the event. The cross section is corrected for detector effects and compared to calculations in perturbative quantum chromodynamics at next-to-leading order accuracy, complemented with electroweak and nonperturbative corrections. New constraints on parton distribution functions are obtained and the inferred value of the strong coupling constant is α S ( M Z ) = 0.1199 ± 0.0015 ( exp ) - 0.0020 + 0.0031 ( theo ) , where M Z is the mass of the Z boson.
  19. Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(4):287.
    PMID: 31007580 DOI: 10.1140/epjc/s10052-018-5752-x
    A study of the associated production of a Z boson and a charm quark jet ( Z + c ), and a comparison to production with a b quark jet ( Z + b ), in p p collisions at a centre-of-mass energy of 8 TeV are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb - 1 , collected with the CMS detector at the CERN LHC. The Z boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of c or b flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with p T ℓ > 20 GeV , | η ℓ | < 2.1 , 71 < m ℓ ℓ < 111 GeV , and heavy flavour jets with p T jet > 25 GeV and | η jet | < 2.5 . The Z + c production cross section is measured to be σ ( p p → Z + c + X ) B ( Z → ℓ + ℓ - ) = 8.8 ± 0.5 (stat) ± 0.6 (syst) pb . The ratio of the Z + c and Z + b production cross sections is measured to be σ ( p p → Z + c + X ) / σ ( p p → Z + b + X ) = 2.0 ± 0.2 (stat) ± 0.2 (syst) . The Z + c production cross section and the cross section ratio are also measured as a function of the transverse momentum of the Z boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.
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