Statistical Code Research Articles

Secondary decay effects of the isospin fractionation in the projectile fragmentation at GeV/nucleon

The isospin fractionations in $$^{124}$$ Sn, $$^{107}$$ Sn + $$^{120}$$ Sn at 600 MeV/nucleon, and $$^{136}$$ Xe, $$^{124}$$ Xe + $$^{208}$$ Pb at 1000 MeV/nucleon are investigated by the isospin-dependent quantum molecular dynamics model coupled with the statistical code GEMINI. The yield ratio as a function of the binding energy difference for light mirror nuclei $$^{3}$$ H/ $$^{3}$$ He, $$^{7}$$ Li/ $$^{7}$$ Be, $$^{11}$$ B/ $$^{11}$$ C, and $$^{15}$$ N/ $$^{15}$$ O is applied to estimate the ratio between neutrons and protons in the gas of the fragmenting system. By comparing the estimated values resulting from the simulations with and without the GEMINI code, it was found that the secondary decay distorts the signal of the isospin fractionation. To minimize the secondary decay effects, the yield ratio of the light mirror nuclei $$^{3}$$ H/ $$^{3}$$ He as well as its double ratio between two systems with different isospin asymmetries of the projectiles is recommended as robust isospin observables.

Temperature and isospin dependence of the level-density parameter in the A≈110 mass region

$\ensuremath{\alpha}$-Particle evaporation spectra were measured at backward angles in $^{16}\mathrm{O}+\phantom{\rule{0.16em}{0ex}}^{94,100}\mathrm{Mo}$ reactions at multiple beam energies. Inverse level-density parameter, $K$, was determined for Cd nuclei of different isospins by simulating high-energy tail of the measured $\ensuremath{\alpha}$-particle evaporation spectra with statistical model code pace2. An overall increasing behavior of the $K$ value is observed with increasing temperature in the range of 1 to 2.5 MeV. It is observed that in the temperature region below 1.8 MeV, the parameter $K$ is higher for the neutron-rich nuclei by around 1 MeV. Semiclassical calculations were performed which treat single-particle level density of neutron and proton on different footing and this can account for the isospin effects. These calculations reproduce the $K$ values as determined from the statistical model analysis of $\ensuremath{\alpha}$-particle evaporation spectra. Present results clearly demonstrate the isospin dependence of the level-density parameter as conjectured by theoretical works.

Evolution of the Earth’s atmosphere during Late Veneer accretion

ABSTRACT Recent advances in our understanding of the dynamical history of the Solar system have altered the inferred bombardment history of the Earth during accretion of the Late Veneer, after the Moon-forming impact. We investigate how the bombardment by planetesimals left-over from the terrestrial planet region after terrestrial planet formation, as well as asteroids and comets, affects the evolution of Earth’s early atmosphere. We develop a new statistical code of stochastic bombardment for atmosphere evolution, combining prescriptions for atmosphere loss and volatile delivery derived from hydrodynamic simulations and theory with results from dynamical modelling of realistic populations of impactors. We find that for an initially Earth-like atmosphere, impacts cause moderate atmospheric erosion with stochastic delivery of large asteroids, giving substantial growth (× 10) in a few ${{\ \rm per\ cent}}$ of cases. The exact change in atmosphere mass is inherently stochastic and dependent on the dynamics of the left-over planetesimals. We also consider the dependence on unknowns including the impactor volatile content, finding that the atmosphere is typically completely stripped by especially dry left-over planetesimals ($\lt 0.02 ~ {{\ \rm per\ cent}}$ volatiles). Remarkably, for a wide range of initial atmosphere masses and compositions, the atmosphere converges towards similar final masses and compositions, i.e. initially low-mass atmospheres grow, whereas massive atmospheres deplete. While the final properties are sensitive to the assumed impactor properties, the resulting atmosphere mass is close to that of current Earth. The exception to this is that a large initial atmosphere cannot be eroded to the current mass unless the atmosphere was initially primordial in composition.

Influence of fast emissions and statistical de-excitation on the isospin transport ratio

Isospin transport ratio is a powerful method to estimate the neutron-proton (n-p) equilibration in heavy-ion collisions, and extensively used to obtain information on the asy-stiffness of the nuclear Equation of State. In fact such a ratio is expected to bypass any perturbations introducing a linear transformation of the chosen observable. In particular, it is supposed to overcome contributions due to emission, either of dynamical or statistical nature, from the primary fragments formed during the collisions. In this paper we explore the validity of this assumption, looking at the quasi-projectile n-p ratio ($N/Z$) in peripheral and semi-peripheral events for Ca+Ca reactions at 35\amev{}, simulated via the Antisymmetrized Molecular Dynamics transport model, coupled to different statistical decay codes. The statistical de-excitation of the primary fragments introduces a linear transformation at relatively high excitation energies (above 2\amev{}) when the residue approaches the Evaporation Attractor Line, while some effect is produced at lower excitation energies due to the occurrence of some non-linearities. As for fast emissions after the end of the projectile-target interaction it is shown that they introduce a non-linear transformation too.

Protocol for Project Fizzyo, an analytic longitudinal observational cohort study of physiotherapy for children and young people with cystic fibrosis, with interrupted time-series design

IntroductionDaily physiotherapy is believed to mitigate the progression of cystic fibrosis (CF) lung disease. However, physiotherapy airway clearance techniques (ACTs) are burdensome and the evidence guiding practice remains weak. This...

A systematic experimental study of pre-compound emission in $$\alpha $$-particle induced reactions on odd mass nuclei A = 103–123

The compound and pre-compound emission processes have been established as two main competing de-excitation modes of an excited nucleus by-dint-of evaporation and emission of light fast particles in low energy $$\alpha $$ -induced reactions, respectively. An existence of the plenty experimental data on above established processes for a wide range of mass nuclei coerces to drive for some systematic trends in such reactions with excitation energy and mass number (A). Present work is an attempt to develop a systematics on the pre-compound emission process by analysing consistent experimental cross-section data of $$\alpha $$ -particle induced reactions on odd Z and odd A isotopic target nuclei viz., $$^{103}$$ Rh, $$^{107}$$ Ag, $$^{109}$$ Ag, $$^{113}$$ In, $$^{115}$$ In, $$^{121}$$ Sb, and $$^{123}$$ Sb, respectively. The analysis of data indicates sarcastic deviation in the experimental cross-section data with respect to calculations performed by the statistical Monte-Carlo code pace4 beyond the peak region. Such deviation becomes more prominent towards tail portion of excitation functions, which is regarded as a significant contribution of the pre-compound emission process. Observed energy dependent uniformity of such deviation for all studied reactions gives a clue for existing some systematics on concerning process with atomic mass number (A). Present study is an extension of previous work [Eur. Phys. J. A 54, 205 (2018)], but rather in more precise way for nearby isotopic target mass nuclei $$^{107}$$ Ag, $$^{109}$$ Ag, $$^{113}$$ In, $$^{115}$$ In, $$^{121}$$ Sb, and $$^{123}$$ Sb, respectively, where role of the Coulomb barrier V $$_b$$ and target deformation is found to be significantly important in the systematic decay of excited nuclei through emission of light fast particles in pre-compound process with mass number (A).

Facilitating reproducible research through direct connection of data analysis with manuscript preparation: StatTag for connecting statistical software to Microsoft Word

ObjectivesTo enhance reproducible research by creating a broadly accessible, free, open-source software tool for connecting Microsoft Word to statistical programs (R/R Markdown, Python, SAS, Stata) so that results may be automatically updated in a manuscript.Materials and MethodsWe developed StatTag for Windows as a Microsoft Word plug-in using C# and for macOS as a native application using Objective-C. Source code is available under the MIT license at https://github.com/stattag.ResultsStatTag links analysis file(s) (R/R Markdown, SAS, Stata, or Python) and a Word document, invokes the statistical program(s) to obtain results, and embeds selected output in the document. StatTag can accommodate multiple statistical programs with a single document and features an interface to view, edit, and rerun statistical code directly from Word.Discussion and ConclusionStatTag may facilitate reproducibility within increasingly multidisciplinary research teams, improve research transparency through review and publication, and complement data-sharing initiatives.

Pre-scission neutron multiplicity in the S32+W184 reaction

The neutron energy spectra in coincidence with both the correlated fission fragments in $^{32}\mathrm{S}+^{184}\mathrm{W}$ reaction forming the compound nucleus $^{216}\mathrm{Th}$ at an excitation energy of 71.31 MeV have been measured at various angles with respect to one of the fission fragments. Pre- and post-scission neutron multiplicities of $2.68\ifmmode\pm\else\textpm\fi{}0.48$ and $3.3\ifmmode\pm\else\textpm\fi{}0.20,$ respectively, have been extracted by analyzing angular correlation of the neutron energy spectra using moving source fitting procedure. The excess pre-scission neutron multiplicity in comparison to statistical model joanne2 code predictions have been converted into total fission delay. A comparative study of fission delay has been carried out for the $^{16}\mathrm{O}+^{208}\mathrm{Pb}$ reaction forming the compound nucleus $^{224}\mathrm{Th}$ at similar excitation energy as in $^{32}\mathrm{S}+^{184}\mathrm{W}$ reaction. Both the reactions have been analyzed within the frame work of joanne2 code including fission delay, deformation dependent level densities, particle binding energies, and transmission coefficients. The observed fission delay for both the reactions can be quantitatively understood if different formation time predicted by dynamical model hicol code are considered.

Evolution of an Asteroid Family under YORP, Yarkovsky, and Collisions

Abstract Any population of asteroids, like asteroid families, will disperse in semimajor axis due to the Yarkovsky effect. The amount of drift is modulated by the asteroid spin state evolution, which determines the balance between the diurnal and seasonal Yarkovsky forces. The asteroid’s spin state is, in turn, controlled in part by the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect. The otherwise smooth evolution of an asteroid can be abruptly altered by collisions, which can cause impulsive changes in the spin state and can move the asteroid onto a different YORP track. In addition, collisions may also alter the YORP parameters by changing the superficial features and overall shape of the asteroid. Thus, the coupling between YORP and Yarkovsky is also strongly affected by the impact history of each body. To investigate this coupling, we developed a statistical code modeling the time evolution of semimajor axis under YORP–Yarkovsky coupling. It includes the contributions of NYORP (normal YORP), TYORP (tangential YORP), and collisions whose effects are deterministically calculated and not added in a statistical way. We find that both collisions and TYORP increase the dispersion of a family in semimajor axis by making the spin axis evolution less smooth and regular. We show that the evolution of a family’s structure with time is complex and collisions randomize the YORP evolution. In our test families, we do not observe the formation of a “YORP-eye” in the semimajor axis versus diameter distribution, even after a long period of time. If present, the “YORP-eye” might be a relic of an initial ejection velocity pattern of the collisional fragments.

Structuring, reuse and analysis of electronic dental data using the Oral Health and Disease Ontology

BackgroundA key challenge for improving the quality of health care is to be able to use a common framework to work with patient information acquired in any of the health and life science disciplines. Patient information collected during dental care exposes many of the challenges that confront a wider scale approach. For example, to improve the quality of dental care, we must be able to collect and analyze data about dental procedures from multiple practices. However, a number of challenges make doing so difficult. First, dental electronic health record (EHR) information is often stored in complex relational databases that are poorly documented. Second, there is not a commonly accepted and implemented database schema for dental EHR systems. Third, integrative work that attempts to bridge dentistry and other settings in healthcare is made difficult by the disconnect between representations of medical information within dental and other disciplines’ EHR systems. As dentistry increasingly concerns itself with the general health of a patient, for example in increased efforts to monitor heart health and systemic disease, the impact of this disconnect becomes more and more severe.To demonstrate how to address these problems, we have developed the open-source Oral Health and Disease Ontology (OHD) and our instance-based representation as a framework for dental and medical health care information. We envision a time when medical record systems use a common data back end that would make interoperating trivial and obviate the need for a dedicated messaging framework to move data between systems.The OHD is not yet complete. It includes enough to be useful and to demonstrate how it is constructed. We demonstrate its utility in an analysis of longevity of dental restorations. Our first narrow use case provides a prototype, and is intended demonstrate a prospective design for a principled data backend that can be used consistently and encompass both dental and medical information in a single framework.ResultsThe OHD contains over 1900 classes and 59 relationships. Most of the classes and relationships were imported from existing OBO Foundry ontologies. Using the LSW2 (LISP Semantic Web) software library, we translated data from a dental practice’s EHR system into a corresponding Web Ontology Language (OWL) representation based on the OHD framework. The OWL representation was then loaded into a triple store, and as a proof of concept, we addressed a question of clinical relevance – a survival analysis of the longevity of resin filling restorations. We provide queries using SPARQL and statistical analysis code in R to demonstrate how to perform clinical research using a framework such as the OHD, and we compare our results with previous studies.ConclusionsThis proof-of-concept project translated data from a single practice. By using dental practice data, we demonstrate that the OHD and the instance-based approach are sufficient to represent data generated in real-world, routine clinical settings. While the OHD is applicable to integration of data from multiple practices with different dental EHR systems, we intend our work to be understood as a prospective design for EHR data storage that would simplify medical informatics. The system has well-understood semantics because of our use of BFO-based realist ontology and its representation in OWL. The data model is a well-defined web standard.

The interplay between the nuclear level density and the separation energy of rotating superheavy nucleus Z = 119 at low temperature regime

The temperature dependence of the level density parameter and the neutron separation energy are determined under statistical assumptions with regard to the excitation energy using the statistical model code developed in FORTRAN language. The quadrupole deformation parameter and the inverse level density parameter are coinciding well with the experimental results concerning the available literatures. The interplay between the level density and the particle separation energy is displayed graphically to locate the possible neutron magicity and found N=176 suits well at low temperature regime. The excitation energy for the possible formation of 119295 is predicted as 33.3 MeV.

Joint analysis of duration of ventilation, length of intensive care, and mortality of COVID-19 patients: a multistate approach

BackgroundThe clinical progress of patients hospitalized due to COVID-19 is often associated with severe pneumonia which may require intensive care, invasive ventilation, or extracorporeal membrane oxygenation (ECMO). The length of intensive care and the duration of these supportive therapies are clinically relevant outcomes. From the statistical perspective, these quantities are challenging to estimate due to episodes being time-dependent and potentially multiple, as well as being determined by the competing, terminal events of discharge alive and death.MethodsWe used multistate models to study COVID-19 patients’ time-dependent progress and provide a statistical framework to estimate hazard rates and transition probabilities. These estimates can then be used to quantify average sojourn times of clinically important states such as intensive care and invasive ventilation. We have made two real data sets of COVID-19 patients (n = 24* and n = 53**) and the corresponding statistical code publically available.ResultsThe expected lengths of intensive care unit (ICU) stay at day 28 for the two cohorts were 15.05* and 19.62** days, while expected durations of mechanical ventilation were 7.97* and 9.85** days. Predicted mortality stood at 51%* and 15%**. Patients mechanically ventilated at the start of the example studies had a longer expected duration of ventilation (12.25*, 14.57** days) compared to patients non-ventilated (4.34*, 1.41** days) after 28 days. Furthermore, initially ventilated patients had a higher risk of death (54%* and 20%** vs. 48%* and 6%**) after 4 weeks. These results are further illustrated in stacked probability plots for the two groups from time zero, as well as for the entire cohort which depicts the predicted proportions of the patients in each state over follow-up.ConclusionsThe multistate approach gives important insights into the progress of COVID-19 patients in terms of ventilation duration, length of ICU stay, and mortality. In addition to avoiding frequent pitfalls in survival analysis, the methodology enables active cases to be analyzed by allowing for censoring. The stacked probability plots provide extensive information in a concise manner that can be easily conveyed to decision makers regarding healthcare capacities. Furthermore, clear comparisons can be made among different baseline characteristics.

Efficient coding of natural scene statistics predicts discrimination thresholds for grayscale textures.

Previously, in Hermundstad et al., 2014, we showed that when sampling is limiting, the efficient coding principle leads to a 'variance is salience' hypothesis, and that this hypothesis accounts for visual sensitivity to binary image statistics. Here, using extensive new psychophysical data and image analysis, we show that this hypothesis accounts for visual sensitivity to a large set of grayscale image statistics at a striking level of detail, and also identify the limits of the prediction. We define a 66-dimensional space of local grayscale light-intensity correlations, and measure the relevance of each direction to natural scenes. The 'variance is salience' hypothesis predicts that two-point correlations are most salient, and predicts their relative salience. We tested these predictions in a texture-segregation task using un-natural, synthetic textures. As predicted, correlations beyond second order are not salient, and predicted thresholds for over 300 second-order correlations match psychophysical thresholds closely (median fractional error <0.13).

Assessing the impact of Social Networking Site use on older people's loneliness and social isolation. A randomized controlled trial: The Aging in a Networked Society-Social Experiment Study (ANS-SE)

IntroductionAn ageing society poses unprecedented challenges to societies. Information and Communication Technologies (ICTs), including Social Networking Sites (SNSs), may contribute to contrast loneliness and social isolation in old age. Despite of the potentialities of SNSs, there is only a handful of studies assessing the causal relationship of SNS use and older people's well-being. This paper aims to provide further evidence on the design of randomised controlled trials exploring the causal impact of SNS use on loneliness and social isolation in old age. Methods and analysisThe Aging in a Networked Society-Social Experiment Study (ANS-SE) is a randomised controlled trial conducted on people aged 75 and over residing in a town located in the Milan area (Italy) aiming to assess the impact of SNS use on loneliness and social isolation (i.e. the primary outcomes of this study). The study is constituted of two stages, i.e. the baseline and the follow up. The experiment is structured into one treatment group and two control groups; the interventions are the attendance to a course on SNS use (T1) and lifestyle education and brain functioning (C1). The inactive control group (C) is constituted of a waiting list. We will perform bivariate and regression analysis. Ethics and disseminationThe study has been approved by the Ethic Committee of the University of Milano Bicocca (prot. 431/2019) and was registered at Clinical Trials.gov (NCT04242628). Written consent was obtained from all respondents. Results from the study will be discussed with the local community and stakeholders, presented in national and international conferences and published in leading peer-review journals. The consent forms, the anonymised dataset, and the relevant statistical codes will be deposited with the Italian Unidata archive, also in charge of releasing the data to the public, upon a short embargo period.

Association of Factor V Leiden With Subsequent Atherothrombotic Events: A GENIUS-CHD Study of Individual Participant Data.

Studies examining the role of factor V Leiden among patients at higher risk of atherothrombotic events, such as those with established coronary heart disease (CHD), are lacking. Given that coagulation is involved in the thrombus formation stage on atherosclerotic plaque rupture, we hypothesized that factor V Leiden may be a stronger risk factor for atherothrombotic events in patients with established CHD. We performed an individual-level meta-analysis including 25 prospective studies (18 cohorts, 3 case-cohorts, 4 randomized trials) from the GENIUS-CHD (Genetics of Subsequent Coronary Heart Disease) consortium involving patients with established CHD at baseline. Participating studies genotyped factor V Leiden status and shared risk estimates for the outcomes of interest using a centrally developed statistical code with harmonized definitions across studies. Cox proportional hazards regression models were used to obtain age- and sex-adjusted estimates. The obtained estimates were pooled using fixed-effect meta-analysis. The primary outcome was composite of myocardial infarction and CHD death. Secondary outcomes included any stroke, ischemic stroke, coronary revascularization, cardiovascular mortality, and all-cause mortality. The studies included 69 681 individuals of whom 3190 (4.6%) were either heterozygous or homozygous (n=47) carriers of factor V Leiden. Median follow-up per study ranged from 1.0 to 10.6 years. A total of 20 studies with 61 147 participants and 6849 events contributed to analyses of the primary outcome. Factor V Leiden was not associated with the combined outcome of myocardial infarction and CHD death (hazard ratio, 1.03 [95% CI, 0.92-1.16]; I2=28%; P-heterogeneity=0.12). Subgroup analysis according to baseline characteristics or strata of traditional cardiovascular risk factors did not show relevant differences. Similarly, risk estimates for the secondary outcomes including stroke, coronary revascularization, cardiovascular mortality, and all-cause mortality were also close to identity. Factor V Leiden was not associated with increased risk of subsequent atherothrombotic events and mortality in high-risk participants with established and treated CHD. Routine assessment of factor V Leiden status is unlikely to improve atherothrombotic events risk stratification in this population.

New multi-part collisional model of the main belt: the contribution to near-Earth asteroids

Aims. We developed a six-part collisional evolution model of the main asteroid belt (MB) and used it to study the contribution of the different regions of the MB to the near-Earth asteroids (NEAs). Methods. We built a statistical code called ACDC that simulates the collisional evolution of the MB split into six regions (namely Inner, Middle, Pristine, Outer, Cybele and High-Inclination belts) according to the positions of the major resonances present there (ν6, 3:1J, 5:2J, 7:3J and 2:1J). We consider the Yarkovsky effect and the mentioned resonances as the main mechanism that removes asteroids from the different regions of the MB and delivers them to the NEA region. We calculated the evolution of the NEAs coming from the different source regions by considering the bodies delivered by the resonances and mean dynamical timescales in the NEA population. Results. Our model is in agreement with the major observational constraints associated with the MB, such as the size distributions of the different regions of the MB and the number of large asteroid families. It is also able to reproduce the observed NEAs with H &lt; 16 and agrees with recent estimations for H &lt; 20, but deviates for smaller sizes. We find that most sources make a significant contribution to the NEAs; however the Inner and Middle belts stand out as the most important source of NEAs followed by the Outer belt. The contributions of the Pristine and Cybele regions are minor. The High-Inclination belt is the source of only a fraction of the actual observed NEAs with high inclination, as there are dynamical processes in that region that enable asteroids to increase and decrease their inclinations.

Isospin dependence of projectile fragmentation at hundreds of MeV/u * * Supported by the National Natural Science Foundation of China (11875328, 11605296, 11635003)

By modeling the fragmentation process using a dynamic model and permitting only evaporation in the statistical code, the main features of a projectile fragmentation at 600 MeV/u were considered in our previous study [Phys. Rev. C, 98: 014610 (2018)]. In this study, we extend this to the isospin dependence of a projectile fragmentation at several hundreds of MeV/u. We searched for isospin observables related to the isospin fractionation to extract the symmetry energy, and found that at the pre-equilibrium stage of the collisions an isospin diffusion will take place and affect the isospin of the final fragments. The isospin fractionation plays a part during the fragmenting stage. Compared to the soft symmetry energy, the stiff symmetry energy provides a smaller repulsive force for neutrons and an attractive force for the protons in a neutron-rich system at a subnormal density, and hence causes a smaller isospin asymmetry of the gas phase, leaving a more neutron-rich liquid phase. An observable robust isospin is proposed to extract the slope of the symmetry energy at normal density based on the isospin dependence of the projectile fragmentation at hundreds of MeV/u.

A How‐To on How to Publish a Preprint

A How‐To on How to Publish a Preprint

Qualitative Research in Surgical Disciplines: Need and Scope

There is a deficient application of qualitative research methods in surgical specialties. The concerned researchers largely focus on quantitative estimates like: health risk, burden, surgical management and objective outcomes. Without qualitative assessment important aspects like: patient’s preparation, perception, satisfaction, coping ability, well-being and functional outcomes are not addressed. In quantitative research, evaluation of pre-set variables is done to primarily study the process and outcomes of healthcare interventions. However, in qualitative research, patient’s experience, emotions, self-image, decision-making, pain perception, coping mechanism and quality of life (QoL) can be assessed. With time, surgeons are emphasizing more on the importance of functional recovery and QoL after surgery in multidisciplinary board discussions, and before making treatment decisions. Qualitative research employs purposive sampling and a meticulous data collection using in-depth interviews (IDIs) and focus group discussions (FGDs) etc. Collected data is analysed using statistical tools post transcription and coding and is suitably presented. Like other research designs, qualitative methods also have uniform criteria’s and standards for quality management. Adoption of qualitative research is critical in filling gaps of patient and surgeon’s perspective and experience of process of surgical care for clinical policy decisions. Integration of qualitative evidence in shared decision-making process will further improve standards and practice of surgical care and enhance doctor-patient relationship.

Abstract 216: Statistical Code Availability From Studies of Medicare Data in General Medical Journals

Background: Open science improves methodological rigor, limits duplication, and helps researchers build upon existing findings. Yet despite the importance of open science in cardiovascular outcomes research, it may be limited by difficulties in accessing statistical code after publication. We evaluated the ease of obtaining statistical code from published research in high-profile journals. Methods: We identified all studies published in 6 general medical journals that utilized Medicare Parts A and B data in 2017 and 2018: Annals of Internal Medicine, BMJ, JAMA, JAMA Internal Medicine, Lancet, and New England Journal of Medicine . We focused on studies utilizing national Medicare data given their widespread use in outcomes research. We targeted recent studies to minimize barriers to accessing code as research teams change over time. Using these criteria, we identified 51 research articles with 41 unique corresponding authors. We contacted these authors to request statistical code for their publications via email up to 3 times at 2-week intervals. When code was provided to us, we assessed its integrity and completeness. Results: Of 51 studies we identified, 3 had full or partial code already publicly available. Of the remaining 48 studies, 7 codes (corresponding to 6 authors) were sent to us, leading to a total of 10 out of 51 articles with full or partial code availability (Figure 1). Overall, we received responses from 19 of the 41 authors. Thirteen corresponding authors declined to share code for numerous reasons. Reasons given for not sharing code included researchers leaving prior positions, analysts leaving research teams, and likelihood of significant delays due to seeking permission from research sponsors. We received no responses from 22 of 41 corresponding authors (Figure 1). Conclusion: We found significant barriers to accessing statistical code after publication in research articles utilizing Medicare data in general medical journals, and we were unable to access statistical codes in over 80% of cases. The inability to obtain codes associated with scientific analyses may represent an important challenge for reproducibility in cardiovascular outcomes research.