bluuebunny/crossref_metadata_2025_split huggingface dataset:
New evidence for a cosmological distribution of stellar mass primordial black holes
Authors: Hawkins M R S 
Published: March 2022

ABSTRACT
In this paper, we show that to explain the observed distribution of amplitudes in a large sample of quasar light curves, a significant contribution from microlensing is required. This implies the existence of a cosmologically distributed population of stellar mass compact bodies making up a large fraction of the dark matter. Our analysis is based on the light curves of a sample of over 1000 quasars, photometrically monitored over a period of 26 yr. The intrinsic variations in quasar luminosity are derived from luminous quasars where the quasar accretion disc is too large to be microlensed by stellar mass bodies, and then synthetic light curves for the whole sample are constructed with the same statistical properties. We then run microlensing simulations for each quasar with convergence in compact bodies appropriate to the quasar redshift assuming a Lambda cold dark matter cosmology. The synthetic light curve is then superimposed on the amplification pattern to incorporate the effects of microlensing. The distribution of the resulting amplitudes can then be compared with observation, giving a very close match. This procedure does not involve optimizing parameters or fitting to the data, as all inputs such as lens mass and quasar disc size come from independent observations in the literature. The overall conclusion of the paper is that to account for the distribution of quasar light curve amplitudes it is necessary to include the microlensing effects of a cosmologically distributed population of stellar mass compact bodies, most plausibly identified as stellar mass primordial black holes.
Postoperative C5 Palsy Following Cervical Laminectomy With Instrumented Fusion Versus Cervical Laminoplasty With Reconstruction
Authors: Kim Jinseong , Shankar Dhruv S. , Bienstock Dennis M. , Gao Michael , Lee Yunsoo , Chaudhary Saad B. , Bronson Wesley H. , Hecht Andrew C. 
Published: March 2022

Study Design:
This was a retrospective cohort study.

Objective:
The objective of this study was to investigate whether cervical laminectomy with instrumented fusion (LF) and cervical laminoplasty with reconstruction (LP) are associated with different rates C5 palsy (C5P) at 1-month follow-up in a single surgeon and nationally representative cohort.

Summary of Background Data:
LF and LP both carry a well-known risk of nerve root injury that most commonly presents as C5P which can reduce patient satisfaction, patient function, and impede patient recovery. The procedure type that is more frequently associated with C5P remains largely unclear.

Methods:
We identified patients undergoing primary LF or LP procedures for the treatment of cervical myelopathy in both a single-surgeon series cohort (2004–2018; Mount Sinai Hospital) and a nationally representative cohort drawn from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database (2006–2017). For the single-surgeon cohort, C5P within 1 month of surgery was recorded. For the NSQIP cohort, peripheral nerve injury (PNI) within 1 month of surgery was recorded and used as a proxy for C5P. Postoperative complications including C5P were compared between cohorts. Multivariable logistic regression was used to evaluate the association between procedure type and postoperative C5P or PNI.

Results:
Without adjusting for covariates, LF patients had a higher rate of 1-month C5P in the single-surgeon cohort (8% vs. 0%, P=0.01). An adjusted odds ratio could not be obtained due to the absence of C5P in the LP group. In the national cohort, LP patients had a significantly higher rate of 1-month PNI on unadjusted analysis (11% vs. 16%, P<0.001). After adjusting for covariates, we found no significant difference in odds of 1-month PNI between LF and LP (adjusted odds ratio=0.84, P=0.07).

Conclusions:
Overall, the single-surgeon series suggest that cervical LF is associated with significantly higher rates of postoperative C5P as compared with LP. These findings are not corroborated by nationally representative data, which showed no difference in PNI rates between LF and LP. A surgeon’s training and experience likely contribute to which procedure has a higher propensity for a C5P as a complication. Regardless, both LF and LP patients should be closely monitored for new-onset C5P during follow-up visits.

Level of Evidence:
Level III.
Cervical Total Disk Replacement
Authors: Guyer Richard D. , Coric Domagoj , Nunley Pierce D. , Ohnmeiss Donna D. 
Published: March 2022

Study Design:This study was a post hoc analysis of data collected from 2 Food and Drug Administration (FDA) Investigational Device Exemption (IDE) trials.Objective:The purposes of this study were to: (1) measure disk space heights adjacent to the level to be treated with a total disk replacement (TDR); (2) analyze cervical disk space heights to be replaced with TDR; and (3) investigate the frequency of use of a smaller height TDR when available.Summary of Background Data:Cervical TDR produces outcomes noninferior or superior to anterior cervical discectomy and fusion. While the restoration of the height of a collapsed, degenerated disk is a surgical goal, there are potential problems with overdistracting the segment with an implant.Methods:Disk heights were measured using radiographs from the 1-level Simplify Cervical Artificial Disk IDE trial, producing values for 259 levels adjacent to the treated level and 162 treated levels. The device is available in 4, 5, and 6 mm heights. The 4 mm height became available only after treatment was 13% complete in the single-level trial and was available for all of the 2-level trial.Results:Measurements of 259 adjacent levels found that 55.2% of disk spaces had a height of <4 mm. Among operated levels, 82.7% were <4 mm. When a 4 mm TDR was available, it was used in 38.4% of operated levels in the 1-level trial and 54.3% of levels in the 2-level trial.Conclusions:Among nonoperated levels, 55.2% were of height <4 mm, suggesting that TDRs of greater heights may potentially overdistract the disk space. The 4 mm TDR was selected by surgeons in 49.4% of all implanted levels, suggesting a preference for smaller TDR height. Further investigation is warranted to determine if the lower height implants are related to clinical and/or radiographic outcomes.Level of Evidence:Level III.
After 9,000 laparotomies for blunt trauma, resuscitation is becoming more balanced and time to intervention shorter: Evidence in action
Authors: Douglas Molly , Obaid Omar , Castanon Lourdes , Reina Raul , Ditillo Michael , Nelson Adam , Bible Letitia , Anand Tanya , Gries Lynn , Joseph Bellal 
Published: March 2022

BACKGROUND
Several advancements in hemorrhage control have been advocated for in the past decade, including balanced transfusions and earlier times to intervention. The aim of this study was to examine the effect of these advancements on outcomes of blunt trauma patients undergoing emergency laparotomy.

METHODS
This is a 5-year (2013–2017) analysis of the Trauma Quality Improvement Program. Adult (18 years or older) blunt trauma patients with early (≤4 hours) packed red blood cell (PRBC) and fresh frozen plasma (FFP) transfusions and an emergency (≤4 hours) laparotomy for hemorrhage control were identified. Time-trend analysis of 24-hour mortality, PRBC/FFP ratio, and time to laparotomy was performed over the study period. The association between mortality and PRBC/FFP ratio, patient demographics, injury characteristics, transfusion volumes, and American College of Surgeons verification level was examined by hierarchical regression analysis adjusting for interyear variability.

RESULTS
A total of 9,773 blunt trauma patients with emergency laparotomy were identified. The mean ± SD age was 44 ± 18 years, 67.5% were male, and median Injury Severity Score was 34 (range, 24–43). The mean ± SD systolic blood pressure at presentation was 73 ± 28 mm Hg, and the median transfusion requirements were PRBC 9 (range, 5–17) and FFP 6 (range, 3–12). During the 5-year analysis, time to laparotomy decreased from 1.87 hours to 1.37 hours (p < 0.001), PRBC/FFP ratio at 4 hours decreased from 1.93 to 1.71 (p < 0.001), and 24-hour mortality decreased from 23.0% to 19.3% (p = 0.014). On multivariate analysis, decreased PRBC/FFP ratio was independently associated with decreased 24-hour mortality (odds ratio, 0.88; p < 0.001) and in-hospital mortality (odds ratio, 0.89; p < 0.001).

CONCLUSION
Resuscitation is becoming more balanced and time to emergency laparotomy shorter in blunt trauma patients, with a significant improvement in mortality. Future efforts should be directed toward incorporating transfusion practices and timely surgical interventions as markers of trauma center quality.

LEVEL OF EVIDENCE
Therapeutic/care management, level III.
A disturbing trend: An analysis of the decline in surgical critical care fellowship training of Black and Hispanic surgeons
Authors: Hambrecht Amanda , Berry Cherisse , DiMaggio Charles , Chiu William , Inaba Kenji , Frangos Spiros , Krowsoski Leandra , Ricketts Greene Wendy , Issa Nabil , Pugh Carla , Bukur Marko 
Published: March 2022

BACKGROUND
Underrepresented minorities in medicine (URiMs) are disproportionally represented in surgery training programs. Rates of URiMs applying to and completing General Surgery residency remain low. We hypothesized that the patterns of URiMs disparities would persist into surgical critical care (SCC) fellowship applicants, matriculants, and graduates.

METHODS
We performed a retrospective analysis of SCC applicants, matriculants, and graduates from 2005 to 2020 using the graduate medical education resident survey and analyzed applicant characteristics using the Surgical Critical Care and Acute Care Surgery Fellowship Application Service from 2018 to 2020. The data were stratified by race/ethnicity and sex. Indicator variables were created for Asian, Hispanic, White, and Black trainees. Yearly proportions for each race/ethnicity and sex categories completing or enrolling in a program were calculated and plotted over time with Loess smoothing lines and overlying 95% confidence bands. The yearly rate and statistical significance of change over time were tested with linear regression models with race/ethnicity and sex proportion as the dependent variables and year as the explanatory variable.

RESULTS
From 2005 to 2020, there were a total of 2,481 graduates. Black men accounted for 4.7% of male graduates with a significant decline of 0.3% per year for the study period of those completing the fellowship (p = 0.02). Black women comprised 6.4% of female graduates and had a 0.6% decline each year (p < 0.01). A similar trend was seen with Hispanic men, who comprised 3.2% of male graduates and had a 0.3% annual decline (p = 0.02). White men had a significant increase in both matriculation to and graduation from SCC fellowships during the same interval. Similarly, Black and Hispanic applicants declined from 2019 to 2020, while the percentage of White applicants increased.

CONCLUSION
Disparities in URiMs representation remain omnipresent in surgery and extend from residency training to SCC fellowship. Efforts to enhance the recruitment and retention of URiMs in SCC training are warranted.

LEVEL OF EVIDENCE
Prognostic and Epidemiologic; level IV.
Healthcare Professionals’ Understandings of the Definition and Determination of Death: A Scoping Review
Authors: Zheng Katina , Sutherland Stephanie , Hornby Laura , Wilson Lindsay , Shemie Sam D. , Sarti Aimee J. 
Published: March 2022

Background.
During the 1950s, advances in critical care, and organ transplantation altered the relationship between organ failure and death. There has since been a shift away from traditional cardiocirculatory based to brain-based criteria of death, with resulting academic controversy, despite the practice being largely accepted worldwide. Our objective is to develop a comprehensive description of the current understandings of healthcare professionals regarding the meaning, definition, and determination of death.

Methods.
Online databases were used to identify papers published from 2003 to 2020. Additional sources were searched for conference proceedings and theses. Two reviewers screened papers using predefined inclusion and exclusion criteria. Complementary searches and review of reference lists complemented the final study selection. A data extraction instrument was developed to iteratively chart the results of the review. A qualitative approach was conducted to thematically analyze the data.

Results.
Seven thousand four hundred twenty-eight references were identified. In total, 75 papers met the inclusion criteria. Fourteen additional papers were added from complementary searches. Most were narratives (35%), quantitative investigations (21%), and reviews (18%). Identified themes included: (1) the historical evolution of brain death (BD), (2) persistent controversies about BD and death determination, (3) wide variability in healthcare professionals’ knowledge and attitudes, (4) critical need for BD determination revision.

Conclusions.
We concluded that although BD is widely accepted, there exists variation in healthcare providers’ understanding of its conceptual basis. Death determination remains a divisive issue among scholars. This review identified a need for increased opportunities for formal training on BD among healthcare providers.
Simulations of molecular photodynamics in long timescales
Authors: Mukherjee Saikat , Pinheiro Max , Demoulin Baptiste , Barbatti Mario 
Published: March 2022

Nonadiabatic dynamics simulations in the long timescale (much longer than 10 ps) are the next challenge in computational photochemistry. This paper delimits the scope of what we expect from methods to run such simulations: they should work in full nuclear dimensionality, be general enough to tackle any type of molecule and not require unrealistic computational resources. We examine the main methodological challenges we should venture to advance the field, including the computational costs of the electronic structure calculations, stability of the integration methods, accuracy of the nonadiabatic dynamics algorithms and software optimization. Based on simulations designed to shed light on each of these issues, we show how machine learning may be a crucial element for long time-scale dynamics, either as a surrogate for electronic structure calculations or aiding the parameterization of model Hamiltonians. We show that conventional methods for integrating classical equations should be adequate to extended simulations up to 1 ns and that surface hopping agrees semiquantitatively with wave packet propagation in the weak-coupling regime. We also describe our optimization of the Newton-X program to reduce computational overheads in data processing and storage.
This article is part of the theme issue ‘Chemistry without the Born–Oppenheimer approximation’.
Machine Learning techniques for the diagnosis of Schizophrenia based on Event Related Potentials
Authors: Febles Elsa Santos , Ortega Marlis Ontivero , Sosa Michell Valdés , Sahli Hichem 
Published: March 2022

AbstractAntecedentThe diagnosis of schizophrenia could be enhanced with objective neurophysiological biomarkers, such as the event related potential features in conjunction with machine learning procedures. A previous work extracted features from event related responses to three oddball paradigms (auditory and visual P300, and mismatch negativity) for the discrimination of schizophrenic patients. They used several classifiers: Naïve Bayes, Support Vector Machine, Decision Tree, Adaboost and Random Forest. The best accuracy was obtained with Random Forest (84.7%).ObjectiveThe aim of this study was to examine the efficacy of Multiple Kernel Learning classifiers and Boruta feature selection method exploring different features for single-subject classification between schizophrenia patients and healthy controls.MethodsA cohort of 54 schizophrenic subjects and 54 healthy control subjects were studied. Three sets of features related to the event related potentials signal were calculated: Peak related features, Peak to Peak related features and Signal related features. The Boruta feature selection algorithm was used to evaluate its impact on classification accuracy. A Multiple Kernel Learning algorithm was applied to address schizophrenia detection.ResultsWe obtained a classification accuracy of 83% using Multiple Kernel Learning classifier with the whole dataset. This result in accuracy triangulates previous work and shows that the differences between schizophrenic patients and controls are robust even when different classifiers are used. Appling the Boruta feature selection algorithm a classification accuracy of 86% was yielded. The variables that contributed most to the classification were mainly related to the latency and amplitude of the auditory P300.ConclusionThis study showed that Multiple Kernel Learning can be useful in distinguishing between schizophrenic patients and controls. Moreover, the combination with the Boruta algorithm provides an improvement in classification accuracy and computational cost.
Closed-loop stimulation of lateral cervical spinal cord in upper-limb amputees to enable sensory discrimination
Authors: Nanivadekar Ameya C. , Chandrasekaran Santosh , Helm Eric R. , Boninger Michael L. , Collinger Jennifer L. , Gaunt Robert A. , Fisher Lee E. 
Published: March 2022

AbstractModern myoelectric prosthetic hands have multiple independently controllable degrees of freedom, but require constant visual attention to use effectively. As we know from motor control of our native limbs, somatosensory feedback is essential to control our movements and provides information not available through vision alone. Similarly, stimulation of the nervous system can potentially provide artificial somatosensory feedback to reduce the reliance on visual cues to efficiently operate prosthetic devices. We have shown previously that epidural stimulation of the lateral cervical spinal cord can evoke tactile sensations perceived as emanating from the missing arm and hand in people with upper-limb amputation. In this study, two subjects with upper-limb amputation used this somatotopically-matched tactile feedback to discriminate object size and compliance while controlling a prosthetic hand. With less than 30 minutes of training each day, both subjects were able to use artificial somatosensory feedback to perform a subset of the discrimination tasks at a success level well above chance. Subject 1 was consistently more adept at determining object size (74% accuracy; chance: 33%) while Subject 2 achieved a higher accuracy level in determining object compliance (60% accuracy; chance 33%). In each subject, discrimination of the other object property was only slightly above or at chance level suggesting that the task design and stimulation encoding scheme are important determinants of which object property could be reliably identified. Our observations suggest that artificial somatosensory feedback provided via spinal cord stimulation can be readily used to infer information about the real-world with minimal training, but that task design is critical and that performance improvements may not generalize across tasks.
Facebook and the creation of the metaverse: radical business model innovation or incremental transformation?
Authors: Kraus Sascha , Kanbach Dominik K. , Krysta Peter M. , Steinhoff Maurice M. , Tomini Nino 
Published: March 2022

PurposeIn a move characterized by ambiguity, Facebook changed its name to Meta in October 2021, announcing a new era of social interaction, enabled by the metaverse technology that appears poised to become the future center of gravity for online social interactions. At first glance, the communicated change signals a radically new business model (BM) based on an unprecedented configuration of the three following components: value creation, value proposition and value capture. The purpose of this paper is to analyze Facebook’s announced changes in its BM to clarify whether the change is as radical as communicated or rather represents an incremental transformation of the current BM.Design/methodology/approachThis investigation adopted an in-depth case study research method. The process included using a structured approach to collect 153 data points, including academic studies and publicly available information, followed by qualitative content analysis.FindingsThe results of our analysis of Facebook’s entrepreneurial journey indicate that the communicated strategic refocusing does not correspond to a radical BM innovation pattern. Even though Facebook’s BM might evolve into the innovation phase, as the current changes appear very futuristic, the authors estimate that the core elements of the BM will change incrementally. The investigation indicates that the underlying logic of the straightforward communicative efforts primarily serves two purposes: to improve the external perception of the company and to disseminate an internal change signal within the organization.Originality/valueThis paper is the first study that takes an entrepreneurship and BM perspective in analyzing Facebook’s approach in rebranding to Meta and refocusing its strategy on building the metaverse. The academic and practical relevance, as well as the potential future impact on business and society, makes the investigation of this case an intriguing prospect. Additionally, the study illuminates the difference between the communicated vision and the real impact on the business, suggesting critical questions about future large-scale rebranding efforts and their effects.
Business school model of social responsibility and sustainability and its impact on small- and mid-sized enterprises
Authors: Ramirez Lozano Julianna Paola , Rojas Valdez Kelly , Marquina Feldman Percy 
Published: March 2022

Purpose
This study aims to define a business school model of social responsibility (SR) and sustainability and describe how the implementation of this model impacts on small- and mid-sized enterprises (SME) and stakeholders in the chain.

Design/methodology/approach
The model was built based on a conceptual analysis about the literary and documentary review in recognized databases of scientific publications and models of SR, accreditations and impact and quality report systems of business schools. The implementation of the model was based on a project that involved Peruvian SME. Data were collected through surveys administered to the study population. The results were confirmed through in-depth interviews. Analytical-synthetic, inductive-deductive-analytical methods were used to present the SR model.

Findings
This model focused on the Sustainable Development Goals (SDGs), partnerships and solved relevant social and economic problems. It also allowed the growth of the micro entrepreneur, the family, the company, the society and other stakeholders in the chain.

Research limitations/implications
The model was validated in one business school but generated more results than the expected. It is recommended to replicate it in other organizations. It has been developed in pandemic and post-pandemic situations.

Practical implications
The model was based on many impact models that considered the SDGs and relevant alliance generation that involved stakeholders in the chain. It also contributed to the development of entrepreneurs and the society.

Social implications
The model benefited people, society and companies. The program aimed to train and formalize entrepreneurs and generate social and economic development.

Originality/value
This study allowed moving from theory to practice in topics of SR and sustainability. The main original aspect is that the model was based on the Unión de Responsabilidad Social Universitaria Latino Americana model; the Business Graduates Association, European Quality Improvement System, Business school Impact System, Global Reporting Initiative standards, the Responsible Business Conduct and the SDGs.