Displaying publications 1 - 20 of 191 in total

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  1. Fulltext Search for direct pair production of supersymmetric partners to the τ lepton in proton-proton collisions at s = 13 TeV
    CMS Collaboration, Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, et al.
    Eur Phys J C Part Fields, 2020;80(3):189.
    PMID: 32226948 DOI: 10.1140/epjc/s10052-020-7739-7
    A search is presented for τ slepton pairs produced in proton-proton collisions at a center-of-mass energy of 13 TeV . The search is carried out in events containing two τ leptons in the final state, on the assumption that each τ slepton decays primarily to a τ lepton and a neutralino. Events are considered in which each τ lepton decays to one or more hadrons and a neutrino, or in which one of the τ leptons decays instead to an electron or a muon and two neutrinos. The data, collected with the CMS detector in 2016 and 2017, correspond to an integrated luminosity of 77.2 fb - 1 . The observed data are consistent with the standard model background expectation. The results are used to set 95% confidence level upper limits on the cross section for τ slepton pair production in various models for τ slepton masses between 90 and 200 GeV and neutralino masses of 1, 10, and 20 GeV . In the case of purely left-handed τ slepton production and decay to a τ lepton and a neutralino with a mass of 1 GeV , the strongest limit is obtained for a τ slepton mass of 125 GeV at a factor of 1.14 larger than the theoretical cross section.
  2. Fulltext MUSiC: a model-unspecific search for new physics in proton-proton collisions at s = 13 TeV
    CMS Collaboration, Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, et al.
    Eur Phys J C Part Fields, 2021;81(7):629.
    PMID: 34727144 DOI: 10.1140/epjc/s10052-021-09236-z
    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV , corresponding to an integrated luminosity of 35.9 fb - 1 , are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.
  3. Fulltext Search for dark matter produced in association with a leptonically decaying Z boson in proton-proton collisions at s = 13 Te
    Sirunyan AM, CMS Collaboration, Tumasyan A, Adam W, Bergauer T, Dragicevic M, et al.
    Eur Phys J C Part Fields, 2021;81(1):13.
    PMID: 33493254 DOI: 10.1140/epjc/s10052-020-08739-5
    A search for dark matter particles is performed using events with a Z boson candidate and large missing transverse momentum. The analysis is based on proton-proton collision data at a center-of-mass energy of 13 Te , collected by the CMS experiment at the LHC in 2016-2018, corresponding to an integrated luminosity of 137 fb - 1 . The search uses the decay channels Z → e e and Z → μ μ . No significant excess of events is observed over the background expected from the standard model. Limits are set on dark matter particle production in the context of simplified models with vector, axial-vector, scalar, and pseudoscalar mediators, as well as on a two-Higgs-doublet model with an additional pseudoscalar mediator. In addition, limits are provided for spin-dependent and spin-independent scattering cross sections and are compared to those from direct-detection experiments. The results are also interpreted in the context of models of invisible Higgs boson decays, unparticles, and large extra dimensions.
  4. Fulltext Measurements of production cross sections of the Higgs boson in the four-lepton final state in proton-proton collisions at s = 13 TeV
    CMS Collaboration, Sirunyan AM, Tumasyan A, Adam W, Andrejkovic JW, Bergauer T, et al.
    Eur Phys J C Part Fields, 2021;81(6):488.
    PMID: 34727143 DOI: 10.1140/epjc/s10052-021-09200-x
    Production cross sections of the Higgs boson are measured in the H → Z Z → 4 ℓ ( ℓ = e , μ ) decay channel. A data sample of proton-proton collisions at a center-of-mass energy of 13 TeV , collected by the CMS detector at the LHC and corresponding to an integrated luminosity of 137 fb - 1 is used. The signal strength modifier μ , defined as the ratio of the Higgs boson production rate in the 4 ℓ channel to the standard model (SM) expectation, is measured to be μ = 0.94 ± 0.07 (stat) - 0.08 + 0.09 (syst) at a fixed value of m H = 125.38 GeV . The signal strength modifiers for the individual Higgs boson production modes are also reported. The inclusive fiducial cross section for the H → 4 ℓ process is measured to be 2 . 84 - 0.22 + 0.23 (stat) - 0.21 + 0.26 (syst) fb , which is compatible with the SM prediction of 2.84 ± 0.15 fb for the same fiducial region. Differential cross sections as a function of the transverse momentum and rapidity of the Higgs boson, the number of associated jets, and the transverse momentum of the leading associated jet are measured. A new set of cross section measurements in mutually exclusive categories targeted to identify production mechanisms and kinematical features of the events is presented. The results are in agreement with the SM predictions.
  5. Ailing neurosurgical services in rural Africa
    Awuah WA, Adebusoye FT, Tenkorang PO, Mehta A, Mustapha MJ, Debrah AF, et al.
    Int J Surg, 2023 Mar 01;109(3):227-229.
    PMID: 36906787 DOI: 10.1097/JS9.0000000000000020
  6. Fulltext The importance of pharmacists in modern day surgery - editorial
    Wireko AA, Ohenewaa Tenkorang P, Tope Adebusoye F, Yaa Asieduwaa O, Mehta A, Fosuah Debrah A, et al.
    Int J Surg, 2023 Feb 01;109(2):88-90.
    PMID: 36799812 DOI: 10.1097/JS9.0000000000000146
  7. Fulltext The state of African surgical research capacity: highlighting the current efforts, challenges, and recommendations - Editorial
    Wireko AA, Ohenewaa Tenkorang P, Tope Adebusoye F, Mehta A, Cheng Ng J, Yaa Asieduwaa O, et al.
    Int J Surg, 2023 Feb 01;109(2):91-93.
    PMID: 36799813 DOI: 10.1097/JS9.0000000000000216
  8. Fulltext Measurement of differential cross sections for Z boson production in association with jets in proton-proton collisions at s = 13 TeV
    Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2018;78(11):965.
    PMID: 30881214 DOI: 10.1140/epjc/s10052-018-6373-0
    The production of a Z boson, decaying to two charged leptons, in association with jets in proton-proton collisions at a centre-of-mass energy of 13 TeV is measured. Data recorded with the CMS detector at the LHC are used that correspond to an integrated luminosity of 2.19 fb -1 . The cross section is measured as a function of the jet multiplicity and its dependence on the transverse momentum of the Z boson, the jet kinematic variables (transverse momentum and rapidity), the scalar sum of the jet momenta, which quantifies the hadronic activity, and the balance in transverse momentum between the reconstructed jet recoil and the Z boson. The measurements are compared with predictions from four different calculations. The first two merge matrix elements with different parton multiplicities in the final state and parton showering, one of which includes one-loop corrections. The third is a fixed-order calculation with next-to-next-to-leading order accuracy for the process with a Z boson and one parton in the final state. The fourth combines the fully differential next-to-next-to-leading order calculation of the process with no parton in the final state with next-to-next-to-leading logarithm resummation and parton showering.
  9. African care for congenital central nervous system disorders: Falling far short of global management standards?
    Wireko AA, Ohenewaa Tenkorang P, Fosuah Debrah A, Akin-Olugbemi T, Yarlagadda R, Mehta A, et al.
    Int J Surg, 2023 Mar 01;109(3):534-535.
    PMID: 36928287 DOI: 10.1097/JS9.0000000000000011
  10. Fulltext Circadian rhythm in systemic autoimmune conditions: Potential of chrono-immunology in clinical practice: A narrative review
    Awuah WA, Huang H, Kalmanovich J, Mehta A, Mikhailova T, Ng JC, et al.
    Medicine (Baltimore), 2023 Aug 11;102(32):e34614.
    PMID: 37565922 DOI: 10.1097/MD.0000000000034614
    The circadian rhythm (CR) is a fundamental biological process regulated by the Earth's rotation and solar cycles. It plays a critical role in various bodily functions, and its dysregulation can have systemic effects. These effects impact metabolism, redox homeostasis, cell cycle regulation, gut microbiota, cognition, and immune response. Immune mediators, cycle proteins, and hormones exhibit circadian oscillations, supporting optimal immune function and defence against pathogens. Sleep deprivation and disruptions challenge the regulatory mechanisms, making immune responses vulnerable. Altered CR pathways have been implicated in diseases such as diabetes, neurological conditions, and systemic autoimmune diseases (SADs). SADs involve abnormal immune responses to self-antigens, with genetic and environmental factors disrupting self-tolerance and contributing to conditions like Systemic Lupus Erythematosus, Rheumatoid Arthritis, and Inflammatory Myositis. Dysregulated CR may lead to increased production of pro-inflammatory cytokines, contributing to the systemic responses observed in SADs. Sleep disturbances significantly impact the quality of life of patients with SADs; however, they are often overlooked. The relationship between sleep and autoimmune conditions, whether causal or consequential to CR dysregulation, remains unclear. Chrono-immunology investigates the role of CR in immunity, offering potential for targeted therapies in autoimmune conditions. This paper provides an overview of the connections between sleep and autoimmune conditions, highlighting the importance of recognizing sleep disturbances in SADs and the need for further research into the complex relationship between the CR and autoimmune diseases.
  11. Biomarkers of Hepatic Dysfunction and Cardiovascular Risk
    Lee TB, Kueh MTW, Jain V, Razavi AC, Alebna P, Chew NWS, et al.
    Curr Cardiol Rep, 2023 Dec;25(12):1783-1795.
    PMID: 37971635 DOI: 10.1007/s11886-023-01993-5
    PURPOSE OF REVIEW: The objective of this manuscript is to examine the current literature on non-alcoholic fatty liver disease (NAFLD) biomarkers and their correlation with cardiovascular disease (CVD) outcomes and cardiovascular risk scores.

    RECENT FINDINGS: There has been a growing appreciation for an independent link between NAFLD and CVD, culminating in a scientific statement by the American Heart Association in 2022. More recently, studies have begun to identify biomarkers of the three NAFLD phases as potent predictors of cardiovascular risk. Despite the body of evidence supporting a connection between hepatic biomarkers and CVD, more research is certainly needed, as some studies find no significant relationship. If this relationship continues to be robust and readily reproducible, NAFLD and its biomarkers may have an exciting role in the future of cardiovascular risk prediction, possibly as risk-enhancing factors or as components of novel cardiovascular risk prediction models.

  12. Embracing robotic surgery in low- and middle-income countries: Potential benefits, challenges, and scope in the future
    Mehta A, Cheng Ng J, Andrew Awuah W, Huang H, Kalmanovich J, Agrawal A, et al.
    Ann Med Surg (Lond), 2022 Dec;84:104803.
    PMID: 36582867 DOI: 10.1016/j.amsu.2022.104803
    Robotic surgery has applications in many medical specialties, including urology, general surgery, and surgical oncology. In the context of a widespread resource and personnel shortage in Low- and Middle-Income Countries (LMICs), the use of robotics in surgery may help to reduce physician burnout, surgical site infections, and hospital stays. However, a lack of haptic feedback and potential socioeconomic factors such as high implementation costs and a lack of trained personnel may limit its accessibility and application. Specific improvements focused on improved financial and technical support to LMICs can help improve access and have the potential to transform the surgical experience for both surgeons and patients in LMICs. This review focuses on the evolution of robotic surgery, with an emphasis on challenges and recommendations to facilitate wider implementation and improved patient outcomes.
  13. NeuroVerse: neurosurgery in the era of Metaverse and other technological breakthroughs
    Kundu M, Ng JC, Awuah WA, Huang H, Yarlagadda R, Mehta A, et al.
    Postgrad Med J, 2023 May 22;99(1170):240-243.
    PMID: 36892407 DOI: 10.1093/postmj/qgad002
    The tremendous evolution in modern technology has led to a paradigm shift in neurosurgery. The latest advancements such as augmented reality, virtual reality, and mobile applications have been incorporated into neurosurgical practice. NeuroVerse, representing the application of the metaverse in neurosurgery, brings enormous potential to neurology and neurosurgery. Implementation of NeuroVerse could potentially elevate neurosurgical and interventional procedures, enhance medical visits and patient care, and reshape neurosurgical training. However, it is also vital to consider the challenges that may be associated with its implementation, such as privacy issues, cybersecurity breaches, ethical concerns, and widening of existing healthcare inequalities. NeuroVerse adds phenomenal dimensions to the neurosurgical environment for patients, doctors, and trainees, and represents an incomparable advancement in the delivery of medicine. Therefore, more research is needed to encourage widespread use of the metaverse in healthcare, particularly focusing on the areas of morality and credibility. Although the metaverse is expected to expand rapidly during and after the COVID-19 pandemic, it remains to be seen whether it represents an emerging technology that will revolutionize our society and healthcare or simply an immature condition of the future.
  14. Unheard voices of global surgery - trauma services in sub-Saharan Africa: a correspondence
    Mehta A, Wireko AA, Ohenewaa Tenkorang P, Ng JC, Rahman TA, Sikora V, et al.
    Int J Surg, 2023 Mar 01;109(3):521-522.
    PMID: 36906789 DOI: 10.1097/JS9.0000000000000145
  15. Fulltext The impact of natural disasters on healthcare and surgical services in low- and middle-income countries
    Salam A, Wireko AA, Jiffry R, Ng JC, Patel H, Zahid MJ, et al.
    Ann Med Surg (Lond), 2023 Aug;85(8):3774-3777.
    PMID: 37554857 DOI: 10.1097/MS9.0000000000001041
  16. The African cancer burden: what is the potential role of modern oncology innovation in reducing the continent's rapidly rising mortality?
    Awuah WA, Ng JC, Mehta A, Nansubuga EP, Abdul-Rahman T, Kundu M, et al.
    Postgrad Med J, 2023 Aug 22;99(1175):941-945.
    PMID: 37280156 DOI: 10.1093/postmj/qgad043
    With increasing prevalence and an expected rise in disease burden, cancer is a cause of concern for African healthcare. The cancer burden in Africa is expected to rise to 2.1 million new cases per year and 1.4 million deaths annually by the year 2040. Even though efforts are being made to improve the standard of oncology service delivery in Africa, the current state of cancer care is not yet on par with the rise in the cancer burden. Cutting-edge technologies and innovations are being developed across the globe to augment the battle against cancer; however, many of them are beyond the reach of African countries. Modern oncology innovations targeted to ward Africa would be promising to address the high cancer mortality rates. The innovations should be cost-effective and widely accessible to tackle the rapidly rising mortality rate on the African continent. Though it may seem promising, a multidisciplinary approach is required to overcome the challenges associated with the development and implementation of modern oncology innovations in Africa.
  17. Fulltext Prospects of evolution-based artificial intelligence models in genome-wide studies to stratify genetic risk variants in nonalcoholic fatty liver disease
    Huang H, Awuah WA, Garg T, Ng JC, Mehta A, Ramamoorthy K, et al.
    Ann Med Surg (Lond), 2023 Jun;85(6):2743-2748.
    PMID: 37363524 DOI: 10.1097/MS9.0000000000000743
    The emergence of genome-wide association studies (GWAS) has identified genetic traits and polymorphisms that are associated with the progression of nonalcoholic fatty liver disease (NAFLD). Phospholipase domain-containing 3 and transmembrane 6 superfamily member 2 are genes commonly associated with NAFLD phenotypes. However, there are fewer studies and replicability in lesser-known genes such as LYPLAL1 and glucokinase regulator (GCKR). With the advent of artificial intelligence (AI) in clinical genetics, studies have utilized AI algorithms to identify phenotypes through electronic health records and utilize convolution neural networks to improve the accuracy of variant identification, predict the deleterious effects of variants, and conduct phenotype-to-genotype mapping. Natural language processing (NLP) and machine-learning (ML) algorithms are popular tools in GWAS studies and connect electronic health record phenotypes to genetic diagnoses using a combination of international classification disease (ICD)-based approaches. However, there are still limitations to machine-learning - and NLP-based models, such as the lack of replicability in larger cohorts and underpowered sample sizes, which prevent the accurate prediction of genetic variants that may increase the risk of NAFLD and its progression to advanced-stage liver fibrosis. This may be largely due to the lack of understanding of the clinical consequence in the majority of pathogenic variants. Though the concept of evolution-based AI models and evolutionary algorithms is relatively new, combining current international classification disease -based NLP models with phylogenetic and evolutionary data can improve prediction accuracy and create valuable connections between variants and their pathogenicity in NAFLD. Such developments can improve risk stratification within clinical genetics and research while overcoming limitations in GWAS studies that prevent community-wide interpretations.
  18. Fulltext Combined measurements of Higgs boson couplings in proton-proton collisions at s = 13 Te
    Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2019;79(5):421.
    PMID: 31178657 DOI: 10.1140/epjc/s10052-019-6909-y
    Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton-proton collision data set recorded with the CMS detector in 2016 at s = 13 Te , corresponding to an integrated luminosity of 35.9 fb - 1 . The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a W or Z boson, or a top quark-antiquark pair) and the following decay modes: H → γ γ , Z Z , W W , τ τ , b b , and μ μ . Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be μ = 1.17 ± 0.10 , assuming a Higgs boson mass of 125.09 Ge . Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.
  19. Fulltext Search for direct pair production of supersymmetric top quarks decaying to all-hadronic final states in pp collisions at [Formula: see text]
    Khachatryan V, Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2016;76(8):460.
    PMID: 28747851 DOI: 10.1140/epjc/s10052-016-4292-5
    Results are reported from a search for the pair production of top squarks, the supersymmetric partners of top quarks, in final states with jets and missing transverse momentum. The data sample used in this search was collected by the CMS detector and corresponds to an integrated luminosity of 18.9[Formula: see text] of proton-proton collisions at a centre-of-mass energy of 8[Formula: see text] produced by the LHC. The search features novel background suppression and prediction methods, including a dedicated top quark pair reconstruction algorithm. The data are found to be in agreement with the predicted backgrounds. Exclusion limits are set in simplified supersymmetry models with the top squark decaying to jets and an undetected neutralino, either through a top quark or through a bottom quark and chargino. Models with the top squark decaying via a top quark are excluded for top squark masses up to 755[Formula: see text] in the case of neutralino masses below 200[Formula: see text]. For decays via a chargino, top squark masses up to 620[Formula: see text] are excluded, depending on the masses of the chargino and neutralino.
  20. Fulltext Forward-backward asymmetry of Drell-Yan lepton pairs in pp collisions at [Formula: see text][Formula: see text]
    Khachatryan V, Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, et al.
    Eur Phys J C Part Fields, 2016;76(6):325.
    PMID: 28280439 DOI: 10.1140/epjc/s10052-016-4156-z
    A measurement of the forward-backward asymmetry [Formula: see text] of oppositely charged lepton pairs ([Formula: see text] and [Formula: see text]) produced via [Formula: see text] boson exchange in pp collisions at [Formula: see text] [Formula: see text] is presented. The data sample corresponds to an integrated luminosity of 19.7[Formula: see text] collected with the CMS detector at the LHC. The measurement of [Formula: see text] is performed for dilepton masses between 40[Formula: see text] and 2[Formula: see text] and for dilepton rapidity up to 5. The [Formula: see text] measurements as a function of dilepton mass and rapidity are compared with the standard model predictions.
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