Excess Of Events Research Articles

The use of a point of care high sensitivity troponin in the investigation of patients presenting to the Emergency Department with undifferentiated chest pain

Abstract Background In 2012 in a hospital, New Zealand, a chest pain pathway was instituted for the use in patients presenting to the Emergency Department (ED) with undifferentiated chest pain. This reduced hospital admissions and ED length of stay (LOS) without adversely affecting outcomes. The pathway consists of risk stratification combined with ECG and troponin testing. The pathway suggests, but does not enforce, that low risk patients can be discharged after a single troponin, intermediate risk patients are for serial troponins (which can be done in ED or the next day in the community), with further testing if appropriate, and high risk patients are reviewed by Cardiology or General medicine. In August 2023, Siemens point of care high sensitivity troponin I (POC-hsTnI) was introduced for the use in ED, although Beckman laboratory troponin I (Lab–hsTnI) is still available. A POC test reduces result turnaround times but until recently there has been a lack of POC assays fulfilling criteria for "high sensitivity". Purpose To ascertain whether the availability of a POC-hsTnI in the ED is a viable option for use in the chest pain pathway Methods A 1 month "snap shot" of all consecutive patients presenting to the ED with chest pain was undertaken and the patients followed for adverse events using electronic notes review. October 2023 was selected for the post POC-hsTnI period and compared with April 2022. Results There were 688 patients presenting to ED with undifferentiated chest pain during October 2023 with a type 1 acute myocardial infarction (AMI) rate of 80 (11.6%), median age 58 (41-72), female 335 (48.7%). POC-hsTnI was used in isolation in 377 (54.8%), in conjunction with Lab-hsTnI in 218 (31.7%) and Lab-hsTnI was used alone in 93 (13.5%). The median turnaround time for POC-hsTnI was 11 minutes (10-11) compared with Lab-hsTnI 87 minutes (61-129). The POC-hsTnI was less sensitive for AMI than the Lab-hsTnI on presentation using the upper reference limit, 72.1% (60.6-81.6) versus 91.5% (83.0-96.4). However, when used with risk stratification, there were no excess adverse events (cardiac death or AMI) at 4 months in patients discharged with a diagnosis of non-cardiac chest pain – 7 (1.4%) (n=495) versus 5 (1.2%), (n=424) in 2022. Median LOS in the ED was 4.4 hours (2.9-6.2) versus 4.0h (3.0-5.9) in 2022. However, a higher proportion of patients had a second cTn: 414 (60.2%) versus 309 (48.4%) and a lower proportion had their second troponin the next day in the community, 28 (6.7%) versus 56 (18.1%). Conclusion The use of a POC-hsTnI is a practical solution to reduce turnaround times for troponin results and has the potential to reduce LOS or allow serial troponins to be measured in a timely manner during their ED visit, obviating the need for a next day community troponin. Whilst POC-hsTnI has a lower early sensitivity for AMI, the use of POC-hsTnI as part of a pathway does not adversely affect outcomes.

A 17 MeV pseudoscalar and the LSND, MiniBooNE and ATOMKI anomalies

In the absence of any new physics signals at the Large Hadron Collider (LHC), anomalous results at low energy experiments have become the subject of increased attention. We focus on three such results from the LSND, MiniBooNE (MB), and ATOMKI experiments. A 17 MeV pseudoscalar mediator (a′) can account for two (8Be and 4He) out of the three cases in which excess events have been seen in pair creation transitions in ATOMKI. We incorporate this mediator in a gauge invariant extension of the Standard Model (SM) with a second Higgs doublet and three singlet (seesaw) neutrinos (Ni, i = 1, 2, 3). N1,2 participate in an interaction in MB and LSND which, with a′ as mediator, leads to the production of e+e− pairs. The Ni also lead to mass-squared differences for SM neutrinos in agreement with global oscillation data. We first show that such a model offers a natural joint solution to the MB and LSND excesses, providing excellent fits to their data. Next, using the values of the couplings to the quarks and electrons which are required to explain pair creation nuclear transition data for 8Be and 4He in ATOMKI, we show that these values still lead to fits for MB and LSND data. However, once ATOMKI is incorporated, we find that strong constraints from the decays K+ → π+a′ (a′ → e+e−) and π+ → e+νee+e− come into play. While our solution is in conformity with the bounds on the former decay, it remains in tension with 90% CL bounds on the latter. We also discuss other constraints from both collider and non-collider experiments and from electroweak precision data, stability and unitarity. We compute the contributions to the electron and muon g – 2 up to two loops for our model. We discuss tests of the model in upcoming experiments.

Assessment of the banking sector's exposure to hydrometeorological events in Costa Rica

This study examines, for the first time, the exposure of the credit portfolio of the banking system in Costa Rica to hydrometeorological events, specifically excess rainfall events, with a focus on firm credit at the canton level. We propose a credit risk indicator to identify cantons with credit portfolios that are more affected by rainfall events. Moreover, we introduce a novel approach with respect to firm level data to assign a single productive location to firms with two or more establishments. We find that cantons with the highest number of excess rainfall events represent a small share of the average credit balance of the country. Furthermore, we observe that the top three cantons with the highest credit risk score are driven by economic activities that are not expected to be notably vulnerable to extreme rainfall.

Analysis of intense hydrological periods based on observed and estimated flow series at a reference station on the Paraná River, Argentina

The hydrological variability and especially extreme phenomena such as droughts and floods affect natural and human systems worldwide. The Paraná River sub-basin, belonging to the La Plata basin, is of great regional importance, and in recent years extreme events have been observed that have impacted socio-economic aspects of the community. This study compares the series of a relevant hydrological index, calculated from observed flows and unregulated contributions within Argentine territory, at the same reference station. Intense hydrological periods are analyzed in both cases, for droughts and excess water events, for subsequent comparison.

Aluminum relaxation as the source of excess low energy events in low threshold calorimeters

Aluminum relaxation as the source of excess low energy events in low threshold calorimeters

JLab spectral functions of argon in nuwro and their implications for MicroBooNE

The Short-Baseline Neutrino program in Fermilab aims to resolve the nature of the low-energy excess events observed in LSND and MiniBooNE, and analyze with unprecedented precision neutrino interactions with argon. These studies require a reliable estimate of neutrino cross sections, in particular for charged current quasielastic scattering (CCQE). Here, we report updates of the uro Monte Carlo generator that, most notably, bring the state-of-the-art spectral functions to model the ground state properties of the argon nucleus, and improve the accuracy of the cross sections at low energies by accounting for the effects of the nuclear Coulomb potential. We discuss these developments in the context of electron and neutrino interactions, by comparing updated uro predictions to experimental data from Jefferson Laboratory Hall A and MicroBooNE. The MicroBooNE CCQE-dominated data are described with the χ2 per degree of freedom of 0.7, compared with 1.0 in the local Fermi gas model. The largest improvement is observed for the angular distributions of the produced protons, where the χ2 reduces nearly by half. Being obtained using the axial form factor parametrization from MINERvA, our results indicate a consistency between the CCQE measurements in MINERvA and MicroBooNE. Published by the American Physical Society 2024

The Effect of Using a Remote Patient Management Platform in Optimizing Guideline-Directed Medical Therapy in Heart Failure Patients: A Randomized Controlled Trial

BackgroundGuideline-directed medical therapy (GDMT) remains underutilized in patients with heart failure with reduced ejection fraction, leading to morbidity and mortality. ObjectivesThe Medly Titrate (Use of Telemonitoring to Facilitate Heart Failure Mediation Titration) study was an open-label, randomized controlled trial to determine whether remote medication titration for patients with heart failure with reduced ejection fraction was more effective than usual care (UC). MethodsIn this study, 108 patients were randomized to remote GDMT titration through the Medly heart failure program (n = 56) vs UC (n = 52). The primary outcome was the proportion of patients completing GDMT titration at 6 months. Secondary outcomes included the number of clinic visits and time required to achieve titration, patient health outcomes, and health care utilization, including urgent clinic/emergency department visits and hospitalization. ResultsAt 6 months, GDMT titration was completed in 82.1% (95% CI: 71.2%-90.8%) of patients in the intervention arm vs 53.8% in UC (95% CI: 41.1%-67.7%; P = 0.001). Remote titration required fewer in-person (1.62 ± 1.09 vs 2.42 ± 1.65; P = 0.004) and virtual clinic visits (0.50 ± 1.08 vs 1.29 ± 1.86; P = 0.009) to complete titration. Median time to optimization was shorter with remote titration (3.42 months [Q1-Q3: 2.99-4.04 months] vs 5.47 months [Q1-Q3: 4.14-7.33 months]; P < 0.001). The number of urgent clinic/emergency department visits (incidence rate ratio of remote vs control groups: 0.90 [95% CI: 0.53-1.56]; P = 0.70) were similar between groups, with a reduction in all-cause hospitalization with remote titration (incidence rate ratio: 0.55 [95% CI: 0.31-0.97]; P = 0.042). ConclusionsRemote titration of GDMT in heart failure with reduced ejection fraction was effective, safe, feasible, and increased the proportion of patients achieving target doses, in a shorter period of time with no excess adverse events compared with UC. (Use of Telemonitoring to Facilitate Heart Failure Mediation Titration [Medly Titrate]; NCT04205513)

Abstract P135: Effect of Cardiovascular Health Improvement at Midlife on Cardiovascular Event and Mortality Risk in Diabetes

Objective: This prospective cohort study examined the relationships between changes in CVH during midlife, as assessed by the Life's Simple 7, and risks of CVD events and all-cause mortality among individuals with diabetes and compared to individuals without diabetes. Methods: The study utilized data from the Atherosclerosis Risk in Communities Study, collected during visits 1 (1987-1989) and visit 3 (1993-1995) with a median follow-up of 23 years. Results: Among the final sample (N=8,741), 806 had diabetes (9.2%). Among participants with diabetes at baseline, 62.3% had consistently low CVH at both visits, 12.0% maintained moderate CVH, and 0.4% maintained favorable CVH. Meanwhile, 15.0% showed improvement, and 10.3% experienced a decline in CVH. Those who improved their CVH status had lower CVD event risks (HR=0.69; 95% CI: 0.50 to 0.93), as did those who maintained moderate CVH (HR=0.68; 95% CI: 0.50 to 0.94) or shifted from moderate to low CVH (HR=0.60; 95% CI: 0.41 to 0.88). These results were largely influenced by positive changes in blood pressure, cholesterol levels, physical activity, and smoking. Similar patterns were observed for all-cause mortality. In comparison to participants without diabetes who maintained a favorable CVH trajectory at midlife, those with diabetes consistently displayed higher risks of CVD events and mortality, regardless of their CVH trajectory (Figure 1). However, individuals with diabetes who maintained a favorable CVH trajectory at midlife had CVD event and mortality risks similar to those without diabetes who had consistently low CVH. Conclusions: For individuals with diabetes at midlife, achieving or maintaining ideal CVH levels through lifestyle factors may help reduce excess CVD events and mortality risk. Nonetheless, CVD risk in diabetes is not completely mitigated by favorable cardiovascular risk factor trajectories.

New Patterns for Highly Pathogenic Avian Influenza and Adjustment of Prevention, Control and Surveillance Strategies: The Example of France.

From 2020 up to summer 2023, there was a substantial change in the situation concerning the high pathogenic avian influenza (HPAI) virus in Europe. This change concerned mainly virus circulation within wildlife, both in wild birds and wild mammals. It involved the seasonality of HPAI detections, the species affected, excess mortality events, and the apparent increased level of contamination in wild birds. The knock-on effect concerned new impacts and challenges for the poultry sector, which is affected by repeated annual waves of HPAI arriving with wild migratory birds and by risks due to viral circulation within resident wild birds across the year. Indeed, exceeding expectations, new poultry sectors and production areas have been affected during the recent HPAI seasons in France. The HPAI virus strains involved also generate considerable concern about human health because of enhanced risks of species barrier crossing. In this article, we present these changes in detail, along with the required adjustment of prevention, control, and surveillance strategies, focusing specifically on the situation in France.

Boosted dark matter from a phantom fluid

It is known that theories of phantom dark energy, considered as quantum fields, predict a continuous production of positive- plus negative-energy particles, from spontaneous decay of the vacuum. We show that this can be a new source of boosted dark matter or radiation, with consequences for direct detection. We set constraints on such models using data from the XENONnT experiment, and we show that recent excess events reported by the DAMIC experiment can be consistently described as coming from dark radiation, produced by vacuum decay, interacting with electrons.

Inflow and infiltration assessment of a prototype sanitary sewer network in a coastal city in China

Abstract A 16-month monitoring program was conducted on a prototype sanitary system in a coastal city in China. The groundwater infiltration (GWI) on dry weather days and the rain-derived inflow and infiltration (RDII) on wet weather days were quantified and analyzed. The proportion of monthly averaged GWI to total flow can be as high as 70% during the observation period mainly due to the high groundwater level. The results also show that the ratio of RDII volume to total rainfall volume (defined as R-value) reaches a limited value of approximately 10% for the studied system when the total rainfall depth increases. A reference indicator Rlim for the limited R-value was proposed for assessing the conditions of sewer systems in terms of RDII. The Rlim value depends on local sewer conditions and in general, a lower Rlim value represents a better performance on RDII and vice versa. This study enriches the case studies on the performance of a specific sanitary sewer system on inflow and infiltration in a typical coastal city with exceptionally high groundwater levels, excess rainfall events in the monitoring season and possible typhoon events, which addresses the unique locational and hydrological properties of a representative coastal city.

Disease mapping: Geographic differences in population rates of interventional treatment for prostate cancer in Australia.

Treatment decisions for men diagnosed with prostate cancer depend on a range of clinical and patient characteristics such as disease stage, age, general health, risk of side effects and access. Associations between treatment patterns and area-level factors such as remoteness and socioeconomic disadvantage have been observed in many countries. To model spatial differences in interventional treatment rates for prostate cancer at high spatial resolution to inform policy and decision-making. Hospital separations data for interventional treatments for prostate cancer (radical prostatectomy, low dose rate and high dose rate brachytherapy) for men aged 40 years and over were modelled using spatial models, generalised linear mixed models, maximised excess events tests and k-means statistical clustering. Geographic differences in population rates of interventional treatments were found (p<0.001). Separation rates for radical prostatectomy were lower in remote areas (12.2 per 10 000 person-years compared with 15.0-15.9 in regional and major city areas). Rates for all treatments decreased with increasing socioeconomic disadvantage (radical prostatectomy 19.1 /10 000 person-years in the most advantaged areas compared with 12.9 in the most disadvantaged areas). Three groups of similar areas were identified: those with higher rates of radical prostatectomy, those with higher rates of low dose brachytherapy, and those with low interventional treatment rates but higher rates of excess deaths. The most disadvantaged areas and remote areas tended to be in the latter group. The geographic differences in treatment rates may partly reflect differences in patients' physical and financial access to treatments. Treatment rates also depend on diagnosis rates and thus reflect variation in investigation rates for prostate cancer and presentation of disease. Spatial variation in interventional treatments may aid identification of areas of under-treatment or over-treatment.

Cover crops, crop insurance losses, and resilience to extreme weather events

AbstractThis study investigates whether cover crop adoption reduces extreme‐weather‐related crop insurance losses. To achieve this objective, we utilize a county‐level panel data set with information on cover crop adoption acres, crop insurance losses (i.e., specifically due to drought, excess heat, or excess moisture), and a number of weather variables. The data cover the main row crop production region in the Midwestern United States (US) for the period 2005 to 2018. We utilize linear fixed effects econometric models and a number of robustness checks in the empirical analysis (i.e., a fractional regression approach, two “external‐instrument‐free” estimation procedures, and a variety of alternative empirical specifications). The estimation methods used take advantage of the panel nature of the data to address various specification and endogeneity issues. We find evidence that counties with higher cover crop adoption tend to have lower crop insurance losses due to drought, excess heat, or excess moisture. Our analysis also indicates that cover crops likely have stronger loss mitigation effects against excess moisture events (like floods) and somewhat weaker loss mitigation impacts against droughts and excess heat. Nonetheless, our results overall suggest that cover crops can enhance resilience to extreme weather events and have the potential to be an effective climate change adaptation strategy in US agriculture.

The Chloroplast Genome of Endive (Cichorium endivia L.): Cultivar Structural Variants and Transcriptome Responses to Stress Due to Rain Extreme Events.

The chloroplast (cp) genome diversity has been used in phylogeny studies, breeding, and variety protection, and its expression has been shown to play a role in stress response. Smooth- and curly-leafed endives (Cichorium endivia var. latifolium and var. crispum) are of nutritional and economic importance and are the target of ever-changing breeding programmes. A reference cp genome sequence was assembled and annotated (cultivar 'Confiance'), which was 152,809 base pairs long, organized into the angiosperm-typical quadripartite structure, harboring two inverted repeats separated by the large- and short- single copy regions. The annotation included 136 genes, 90 protein-coding genes, 38 transfer, and 8 ribosomal RNAs and the sequence generated a distinct phyletic group within Asteraceae with the well-separated C. endivia and intybus species. SSR variants within the reference genome were mostly of tri-nucleotide type, and the cytosine to uracil (C/U) RNA editing recurred. The cp genome was nearly fully transcribed, hence sequence polymorphism was investigated by RNA-Seq of seven cultivars, and the SNP number was higher in smooth- than curly-leafed ones. All cultivars maintained C/U changes in identical positions, suggesting that RNA editing patterns were conserved; most cultivars shared SNPs of moderate impact on protein changes in the ndhD, ndhA, and psbF genes, suggesting that their variability may have a potential role in adaptive response. The cp transcriptome expression was investigated in leaves of plants affected by pre-harvest rainfall and rainfall excess plus waterlogging events characterized by production loss, compared to those of a cycle not affected by extreme rainfall. Overall, the analyses evidenced stress- and cultivar-specific responses, and further revealed that genes of the Cytochrome b6/f, and PSI-PSII systems were commonly affected and likely to be among major targets of extreme rain-related stress.

Sensitivity potential to a light flavor-changing scalar boson with DUNE and NA64mu

In this work, we report on the sensitivity potential of complementary muon-on-target experiments to new physics using a scalar boson benchmark model associated with charged lepton flavor violation. The NA64mu experiment at CERN uses a 160-GeV energy muon beam with an active target to search for excess events with missing energy and momentum as a probe of new physics. At the same time, the proton beam at Fermilab, which is used to produce the neutrino beam for the Deep Underground Neutrino Experiment (DUNE), will also produce a high-intensity muon beam dumped in an absorber. Combined with the liquid argon near detector, the system could be used to search for similar scalar boson particles with a lower-energy but higher-intensity beam. We find that both NA64mu and DUNE could cover new, unexplored parts of the parameter space of the same benchmark model, providing a complementary way to search for new physics.

55-OR: HSK7653, a Novel Ultralong-Acting DPP-4 Inhibitor, as Monotherapy in Patients With Type 2 Diabetes—A Randomized, Double-Blind, Placebo-Controlled Phase III Trial

Background: HSK7653 is a novel ultralong-acting DPP-4 inhibitor that maintains the average plasma DPP-4 inhibition over 80% for 14 days after 10mg or 25mg dosing. This randomized, double-blind, placebo-controlled phase III trial was conducted to evaluate the efficacy and safety of HSK7653 biweekly as monotherapy for 52 weeks in drug naive type 2 diabetes patients with inadequate glycemic control on diet and exercise. Methods: A total of 475 patients with a mean HbA1c level of 8.1% were randomized to HSK7653 10mg, 25mg or placebo biweekly at a ratio of 1:1:1 for 24 weeks of double-blind treatment, followed by 28 weeks of open-label extension treatment with HSK7653 25mg for all patients. The primary endpoint was the change in HbA1c from baseline at 24 weeks. Results: At week 24, the least-squares mean change in HbA1c from baseline was -0.96% in HSK7653 10mg, -0.92% in HSK7653 25mg and -0.33% in placebo. HSK7653 10mg and 25mg treatment resulted in significant placebo-subtracted changes in HbA1c of -0.63% (95% CI: -0.81%, -0.46%, p&amp;lt;0.0001) and -0.59% (95% CI: -0.77%, -0.42%, p&amp;lt;0.0001), respectively. The percentage of patients achieving HbA1c&amp;lt;7.0% was 44.2% in HSK7653 10mg group and 44.4% in HSK7653 25mg group versus 20.6% in placebo group (p&amp;lt;0.0001 for HSK7653 groups vs. placebo). No meaningful body weight changes were observed in all treatment groups. In the open-label extension treatment (from week 24 to week 52), the sustaining reduction of HbA1c from baseline were observed in HSK7653 10mg switched to 25mg group and HSK7653 25mg maintenance group. There were no excess hypoglycemia events in HSK7653 vs. placebo, and the incidence of adverse events was similar in all groups during the treatment. Conclusions: In people with type 2 diabetes who had inadequate glycemic control on diet and exercise, HSK7653 monotherapy significantly improved glycemic control with well tolerability and safety. Clinical trial information: NCT04556851. Disclosure L.Ji: Other Relationship; Eli Lilly and Company, Novo Nordisk, Merck &amp; Co., Inc., Bayer Inc., Sanofi-Aventis U.S., Roche Pharmaceuticals, MSD Life Science Foundation, AstraZeneca, Boehringer Ingelheim Inc., Abbott, Metronics. F.Bian: None. T.Pan: None. H.Jiang: None. C.Jiang: None. Q.Ren: None.

More ingredients for an Altarelli cocktail at MiniBooNE

The MiniBooNE excess persists as a significant puzzle in particle physics. Given that the MiniBooNE detector cannot discriminate between electron-like signals and backgrounds due to photons, the goal of this work is to study photon backgrounds in MiniBooNE in depth. We first consider a novel single-photon background arising from multi-nucleon scattering with coherently enhanced initial or final state radiation. This class of processes, which we dub “2p2hγ” (two-particle–two-hole + photon) can explain ~40 of the ~560 excess events observed by MiniBooNE in neutrino mode. Second, we consider the background from neutral-current single-π0 production, where two photons from π0 → γγ decay are mis-identified as an electron-like shower. We construct a phenomenological likelihood that reproduces MiniBooNE’s π0 → γγ background faithfully. Even with data-driven background estimation techniques, we find there is a residual dependence on the Monte Carlo generator used. Our results motivate a reduction in the significance of the MiniBooNE excess by 0.4σ.

Estimating the Impact of Climate and Vegetation Changes on Runoff Risk across the Hawaiian Landscape

In Hawai’i, ecosystem conservation practitioners are increasingly considering the potential ecohydrological benefits from applied conservation action to mitigate the degrading impacts of runoff on native and restored ecosystems. One determinant of runoff is excess rainfall events where rainfall rates exceed the infiltration capacity of soils. To help understand runoff risks, we calculated the probability of excess rainfall events across the Hawaiian landscape by comparing the probability distributions of projected rainfall frequency and land-cover-specific infiltration capacity. We characterized soil infiltration capacity based on different land cover types (bare soil, grasses, and woody vegetation) and compared them to the frequency of large rainfall events under current and future climate scenarios. We then mapped the potential risk of excess rainfall across the main Hawaiian Islands. Our results show that land cover type has a very large effect on runoff risk as excess rainfall conditions are 234% more likely in bare soil and 75% more likely in grasslands compared to woody forests and shrublands. In contrast, projected shifts in rainfall intensity by end-of-century show little impact on these probabilities and thus, the risk of runoff. This indicates that the probability of excess rainfall is primarily driven by differences in land cover and not by current or potential shifts in rainfall patterns across the Hawaiian landscape. The ability to estimate the risk of potentially ecologically and economically costly runoff based on changes of land cover is useful for managers focused on invasive species control and restoration planning, especially for native and endemic ecosystems unique to the State of Hawai’i.

Longitudinal Force Measurement and its Relationship to Technical Competence for Esophageal Anastomosis in a Thoracoscopic Esophageal Atresia/Tracheo-Esophageal Fistula Simulator

PurposeThoracoscopic esophageal atresia with tracheo-esophageal fistula (EA/TEF) repair requires the gentle manipulation of delicate tissue. Force sensors were attached to the upper and lower esophagus of a 3D-printed EA/TEF simulator to explore force parameters as markers of performance. MethodsParticipants completed one intracorporeal suture between the anterior walls of upper and lower esophageal ends. Longitudinal force data were recorded at each end. A blinded pediatric surgeon marked attempt videos. Excessive force events, maximum tension, and force interquartile range (IQR) were measured. Data were reported as median (range) significance of p < 0.05. Results17 participants of varying levels of experience performed the task. OSATS scores showed significant differences between experts and novices. Experts completed the task in a median time of 4 min. They used lower maximum tension, higher force IQR, and had fewer excess force events compared to the intermediate and novice groups. DiscussionThe application of force was dependent on expertise with more skilled participants having fewer excess force events. The higher expert force IQR likely reflects the consistent tension needed for task completion. Analysis of force data may be an indicator of competence, and trainees may benefit from a thoracoscopic simulator which provides force data feedback. Level of evidenceNot applicable.

Detection of the Crab Nebula using a randomforest analysis of the first TAIGA IACT data

ABSTRACT The Tunka Advanced Instrument for Gamma- and cosmic-ray Astronomy (TAIGA) is a multicomponent experiment for the measurement of TeV to PeV gamma- and cosmic rays. Our goal is to establish a novel hybrid direct air shower technique, sufficient to access the energy domain of the long-sought Pevatrons. The hybrid air Cherenkov light detection technique combines the strengths of the HiSCORE shower front sampling array, and two ∼4 m class, ∼9.6° field of view Imaging Air Cherenkov Telescopes (IACTs). The HiSCORE array provides good angular and shower core position resolution, while the IACTs provide the image shape and orientation for gamma-hadron separation. In future, an additional muon detector will be used for hadron tagging at ≥100 TeV energies. Here, only data from the first IACT of the TAIGA experiment are used. A randomforest algorithm was trained using Monte Carlo (MC) simulations and real data, and applied to $85\, \mathrm{h}$ of selected observational data tracking the Crab Nebula at a mean zenith angle of 33.5°, resulting in a threshold energy of 6 TeV for this data set. The analysis was performed using the gammapy package. A total of 163.5 excess events were detected, with a statistical significance of 8.5 σ. The observed spectrum of the Crab Nebula is best fit with a power law above 6 TeV with a flux normalization of (3.20 ± 0.42) · 10−10 TeV−1 cm−2 s−1at a reference energy of $13\, \mathrm{TeV}$ and a spectral index of −2.74 ± 0.16.