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ADVANCES IN THE MOLECULAR SIMULATION OF MICROPHASE FORMERS
No full textThis chapter details the different experimental microphase formers and provides a minimal theoretical framework to present the simulation challenges associated with studying model microphase formers. Block copolymers are by far the most studied microphase formers. The chapter focuses on the phenomenological field theory description of the universality of the microphase formation and of the nature of the order-disorder transition. The chapter describes molecular simulation methods that have been specifically designed to achieve equilibrium in the periodic microphase regime. It details the thermodynamic framework and a free energy integration simulation method, followed by a concrete introduction to the ghost particle/cluster switching method. The chapter discusses several classical Monte Carlo algorithms to enhance the efficiency of simulating disordered microphases. It presents three models for which quantitative results have been obtained: a one-dimensional, a lattice, and an off-lattice microphase former. Fine-tuning colloidal suspensions to allow the formation of periodic microphases thus remains an open experimental problem
Ventilator Mode Does Not Influence Blood Loss or Transfusion Requirements During Major Spine Surgery: A Retrospective Study.
No full textBackgroundBlood loss during adult spinal deformity surgery is multifactorial. Anesthetic-related factors, such as mode of mechanical ventilation, may contribute to intraoperative blood loss. The aim of this study was to determine the influence of ventilator mode and ventilator parameters on intraoperative blood loss and transfusion requirements in patients undergoing prone position spine surgery.MethodsThis single-center retrospective study examined electronic medical records of patients ≥18 years of age who underwent elective prone position spine surgery between May 2015 and June 2016. Associations between ventilator mode and ventilator parameters with intraoperative estimated blood loss (EBL), packed red blood cells (PRBCs), fresh-frozen plasma (FFP), cryoprecipitate and platelet transfusions, and subfascial drain output were examined using multiple linear regression models controlling for age, sex, American Society of Anesthesiologist (ASA) physical status score, body mass index (BMI), preoperative blood coagulation parameters and laboratory values, operative levels, cage constructs, osteotomies, transforaminal lumbar interbody fusions, laminectomies, reoperation, spine surgery invasiveness index, and operative time. In a secondary analysis, EBL, blood product transfusions, and postoperative drain output were compared between pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) propensity score-matched cohorts.ResultsNine hundred forty-six records were reviewed, and 822 were included in the analysis. After adjusting for confounding, no statistically significant associations were observed between mode of ventilation and intraoperative EBL (estimate, -2; 95% confidence interval [CI], -248 to 245; P = .99) or blood product transfusions (PRBC: estimate, -9; 95% CI, -154 to 135; P = .90; FFP: estimate, -3; 95% CI, -59 to 54; P = .93; cryoprecipitate: estimate, -14; 95% CI, -70 to 43; P = .63; platelets: -7; 95% CI, -39 to 24; P = .64). After propensity score matching (n = 27 per group), no significant differences were observed in EBL (mean difference, 525 mL; 95% CI, -15 to 1065; P = .056) or blood transfusions (PRBC: mean difference, 208 mL; 95% CI, -23 to 439; P = .077; FFP (mean difference, 34 mL; 95% CI, -17 to 84; P = .19); cryoprecipitate (mean difference, 55 mL; 95% CI, -24 to 133; P = .17); or platelets (mean difference, 26 mL; 95% CI, -12 to 64; P = .18) between PCV and VCV groups.ConclusionsIn prone position spine surgery, neither mode of mechanical ventilation nor airway pressure is associated with intraoperative blood loss or need for allogeneic transfusion. Use of modern ventilation strategies using lung protective techniques may mitigate differences in blood loss previously observed between PCV and VCV modes
Incidence and risk factors of postoperative neurologic decline after complex adult spinal deformity surgery: results of the Scoli-RISK-1 study.
No full textBackground contextSignificant variability in neurologic outcomes after surgical correction for adult spinal deformity (ASD) has been reported. Risk factors for decline in neurologic motor outcomes are poorly understood.PurposeThe objective of the present investigation was to identify the risk factors for postoperative neurologic motor decline in patients undergoing complex ASD surgery.Study design/settingThis is a prospective international multicenter cohort study.Patient sampleFrom September 2011 to October 2012, 272 patients undergoing complex ASD surgery were prospectively enrolled in a multicenter, international cohort study in 15 sites.Outcome measuresNeurologic decline was defined as any postoperative deterioration in American Spinal Injury Association lower extremity motor score (LEMS) compared with preoperative status.MethodsTo identify risk factors, 10 candidate variables were selected for univariable analysis from the dataset based on clinical relevance, and a multivariable logistic regression analysis was used with backward stepwise selection.ResultsComplete datasets on 265 patients were available for analysis and 61 (23%) patients showed a decline in LEMS at discharge. Univariable analysis showed that the key factors associated with postoperative neurologic deterioration included older age, lumbar-level osteotomy, three-column osteotomy, and larger blood loss. Multivariable analysis revealed that older age (odds ratio [OR]=1.5 per 10 years, 95% confidence interval [CI] 1.1-2.1, p=.005), larger coronal deformity angular ratio [DAR] (OR=1.1 per 1 unit, 95% CI 1.0-1.2, p=.037), and lumbar osteotomy (OR=3.3, 95% CI 1.2-9.2, p=.022) were the three major predictors of neurologic decline.ConclusionsTwenty-three percent of patients undergoing complex ASD surgery experienced a postoperative neurologic decline. Age, coronal DAR, and lumbar osteotomy were identified as the key contributing factors
How war-related deprivation affects political participation: Evidence from education loss in Liberia
No full textHow does civil war affect citizen engagement with democracy? Civilians who live through warfare face numerous disruptions to everyday life that can have permanent effects on political engagement even after peace is achieved. This article analyzes the role of depressed living standards resulting from education loss during the Liberia Civil War as a case study of war-related deprivation. I argue that the negative effects of war on education and economic outcomes clash with the expectations that citizens have for postwar democracy, with adverse consequences for political participation. I demonstrate support for this argument using a mixed methods approach, combining qualitative interviews with census, voting, and Afrobarometer survey data. I leverage a difference-in-differences identification strategy to causally identify the negative impact of conflict on human capital for a generation of young adults, and on the downstream consequences of disruptions in education on political participation. Results indicate that children who were of school age during the civil war are differentially less likely to have any formal schooling by the end of the war. I further find that educational deficiencies disproportionately decrease postwar job prospects, breeding resentment against the newly elected government. This extends to political participation: those who lost out on educational opportunities due to war exhibit lower political engagement and less desire to engage with democratic processes
Cardiovascular Disease Risk Management in Persons With HIV: Does Clinician Specialty Matter?
No full textBackgroundThe impact of clinician specialty on cardiovascular disease risk factor outcomes among persons with HIV (PWH) is unclear.MethodsPWH receiving care at 3 Southeastern US academic HIV clinics between January 2014 and December 2016 were retrospectively stratified into 5 groups based on the specialty of the clinician managing their hypertension or hyperlipidemia. Patients were followed until first atherosclerotic cardiovascular disease event, death, or end of study. Outcomes of interest were meeting 8th Joint National Commission (JNC-8) blood pressure (BP) goals and National Lipid Association (NLA) non-high-density lipoprotein (HDL) goals for hypertension and hyperlipidemia, respectively. Point estimates for associated risk factors were generated using modified Poisson regression with robust error variance.ResultsOf 1667 PWH in the analysis, 965 had hypertension, 205 had hyperlipidemia, and 497 had both diagnoses. At study start, the median patient age was 52 years, 66% were Black, and 65% identified as male. Among persons with hypertension, 24% were managed by an infectious diseases (ID) clinician alone, and 5% were co-managed by an ID clinician and a primary care clinician (PCC). Persons managed by an ID clinician were less likely to meet JNC-8 hypertension targets at the end of observation than the rest of the cohort (relative risk [RR], 0.84; 95% CI, 0.75-0.95), but when mean study blood pressure was considered, there was no difference between persons managed by ID and the rest of the cohort (RR, 0.96; 95% CI, 0.88-1.05). There was no significant association between the ID clinician managing hyperlipidemia and meeting NLA non-HDL goals (RR, 0.89; 95% CI, 0.68-1.15).ConclusionsClinician specialty may play a role in suboptimal hypertension outcomes in persons with HIV
Changes in radiographic and clinical outcomes with primary treatment adult spinal deformity surgeries from two years to three- to five-years follow-up.
No full textStudy designRetrospective analysis of data entered prospectively into a multicenter database-clinical and radiographic outcomes assessment.ObjectiveOur hypothesis is that between the 2-year and the 3- to 5-year points surgically treated adult spinal deformity patients will show significant reduction in outcomes by Scoliosis Research Society (SRS), Oswestry Disability Index (ODI), and numerical rating scale back and leg pain scores and will show increasing thoracic kyphosis, loss of lumbar lordosis, and loss of coronal and sagittal balance.Summary of background dataMost analyses of primary presentation adult spinal deformity surgery assess 2-year follow-up. However, it is established that in some patients unfavorable events occur between the 2-year and 5-year points.MethodsThe cohort of 113 patients entered into a multicenter database with complete preoperative, 2-year, and 3- to 5-year data. All patients who had adult spinal deformity and surgical treatment represented their first reconstruction. Diagnoses were scoliosis (82.5%), kyphosis (10%), and scoliosis and kyphosis combined (7.5%). Outcome measures and basic radiographic parameters (curve size, thoracic and lumbar sagittal plane, coronal and sagittal balance) were assessed at those 3 time intervals. Complications (pseudarthrosis/implant failure, infection, and junctional deformities) were assessed at the 2-year and the 3- to 5-year (mean, 3.76 years) points. RESULTS.: The mean major curve Cobb angle (preoperative, 57°; 2-year, 29°; 3-5 year, 26°); thoracic kyphosis T5 to T12 (30°, 31°, 32°) and lumbar lordosis T12 to sacrum (48°, 49°, 51°) did not change from the 2-year to ultimate follow-up. Likewise, coronal and sagittal balance parameters were the same at 2-year and ultimate follow-up. SRS total scores and modified ODI were similar at the 2 year and final follow-up (SRS: 3.89-3.88; ODI: 19-18). Preoperative SRS total score was 3.17. Six patients demonstrated complications at the 2-year point and additional 9 patients demonstrated complications at the 3- to 5-year point. Those 9 patients with complications at ultimate follow-up demonstrated significant deterioration in their ODI and SRS scores when compared with the patients who did not have complications at ultimate follow-up.ConclusionContrary to our hypothesis, we could not establish deterioration in mean radiographic or clinical outcomes between the 2-year and 3- to 5-year follow-up points when analyzing the group as a whole. However, for the 9 patients who experienced complications between 3- and 5-year follow-up, their outcomes were significantly worse than for the other 104 patients.One should not anticipate an overall radiographic and clinical deterioration of the outcomes of surgically treated primary presentation adult spinal deformity patients in this studied time interval. However, close to 10% of patients will experience a new complication at the 3- to 5-year point, most commonly implant failure/nonunion and/or junctional kyphosis, which will negatively effect the patient-reported outcome
The impact of the COVID-19 pandemic on vascular surgery practice in the United States.
No full textBackgroundThe coronavirus disease 2019 (COVID-19) pandemic has led to widespread postponement and cancelation of elective surgeries in the United States. We designed and administered a global survey to examine the impact of COVID-19 on vascular surgeons. We describe the impact of the pandemic on the practices of vascular surgeons in the United States.MethodsThe Pandemic Practice, Anxiety, Coping, and Support Survey for Vascular Surgeons is an anonymous cross-sectional survey sponsored by the Society for Vascular Surgery Wellness Task Force disseminated April 14 to 24, 2020. This analysis focuses on pattern changes in vascular surgery practices in the United States including the inpatient setting, ambulatory, and vascular laboratory setting. Specific questions regarding occupational exposure to COVID-19, adequacy of personal protective equipment, elective surgical practice, changes in call schedule, and redeployment to nonvascular surgery duties were also included in the survey. Regional variation was assessed. The survey data were collected using REDCap and analyzed using descriptive statistics.ResultsA total of 535 vascular surgeons responded to the survey from 45 states. Most of the respondents were male (73.1%), white (70.7%), practiced in urban settings (81.7%), and in teaching hospitals (66.8%). Almost one-half were in hospitals with more than 400 beds (46.4%). There was no regional variation in the presence of preoperative COVID-19 testing, COVID-19 OR protocols, adherence to national surgical standards, or the availability of personal protective equipment. The overwhelming majority of respondents (91.7%) noted elective surgery cancellation, with the Northeast and Southeast regions having the most case cancellations 94.2% and 95.8%, respectively. The Northeast region reported the highest percentage of operations or procedures on patients with COVID-19, which was either identified at the time of the surgery or later in the hospital course (82.7%). Ambulatory visits were performed via telehealth (81.3%), with 71.1% having restricted hours. More than one-half of office-based laboratories (OBLs) were closed, although there was regional variation with more than 80% in the Midwest being closed. Cases performed in OBLs focused on critical limb ischemia (42.9%) and dialysis access maintenance (39.9%). Call schedules modifications were common, although the number of call days remained the same (45.8%).ConclusionsVascular surgeons in the United States report substantial impact on their practices during the COVID-19 pandemic, and regional variations are demonstrated, particularly in OBL use, intensive care bed availability, and COVID-19 exposure at work
Appropriate dose of regorafenib based on body weight of colorectal cancer patients: a retrospective cohort study.
No full textPURPOSE: Previous randomized studies have shown a survival benefit of using regorafenib but a high rate of adverse events in unresectable colorectal cancer patients. To reduce these adverse events and improve the tolerability, we examined the appropriate dose of regorafenib based on body weight. METHODS: We used a nationwide claims database in Japan and examined the efficacy and safety of regorafenib for patients with metastatic colorectal cancer between groups divided by body weight (60 kg) and median average dose (120 mg) between 2013 and 2018. We also assessed overall survival (OS) and adverse events between these groups. RESULTS: We identified 2530 Japanese patients (heavy weight/high dose: 513, light weight/low dose: 921, heavy weight/low dose: 452, and light weight/high dose: 644). There was no significant difference in the adverse events and OS after inverse probability treatment weighting (IPTW) adjustment between heavy weight/high dose group and light weight/low dose group (hazard ratio, HR=0.97). Among the light-weight patients, higher average dose was associated with shorter OS (IPTW adjusted HR=1.21, 95% CI 1.05 - 1.39, Table 3) while among the heavy-weight patients, there was no significant difference in OS between high and low dose groups (IPTW adjusted HR=1.14, 95% CI 0.95 - 1.37). CONCLUSION: The findings suggest that a low dose of regorafenib for light-weight patients may be as safe and effective as high doses for heavy-weight patients. Further studies should be conducted to identify an appropriate dose based on each patient's physique and condition
Effective Field Theory Studies of Few-nucleon Systems: Fundamental Symmetry Violation, Electromagnetic Interactions, and Direct Detection of Dark Matter
No full textEffective field theory (EFT) has evolved as a powerful model-independent theoretical framework for illuminating complicated interactions across a wide range of physics areas and subfields. It takes advantage of the scale separation exsiting in physical systems to invoke a systematic expansion to capture the physics at a certain energy scale. The symmetries of the high-energy/short-distance theory constrain these interactions, limiting the number of unknown low-energy coefficients (LECs) that must be extracted from the experiment or calculated directly from the underlying theory.The utilization of EFTs in nuclear physics has facilitated our understanding of atomic nuclei and bridged the gap between quantum chromodynamics (QCD), the theory of strong interactions, and nuclear structure and interactions. In particular, EFTs have been proven successful in describing the structure and dynamics of few-body nuclei. In this dissertation, we present several studies on applying the EFT technique to research problems in nuclear physics. We first apply pionless EFT (\eftnopi) to study parity violation in two-nucleon systems and the dark matter scattering off light nuclei. The operators contributing to these elusive processes are accompanied by unknown LECs. We show that the large-\Nc expansion can systematically separate these LECs into those that occur at leading order in and those that occur at next-to-leading order in \Nc. The large-\Nc ordering could provide a powerful reduction in the number of experiments needed to understand these processes at every order in this combined expansion, as well as help prioritize future experiments and lattice QCD calculations.In the second part, we consider the low-energy proton–deuteron and deuteron-Helium-4 systems at low energies in cluster EFT. Below the deuteron breakup threshold, the deuteron and Helium-4 can be treated as structureless degrees of freedom. In particular, we focus on the deuteron + Helium-4 cluster configuration of the Lithium-6 nucleus. We illustrate how to directly extract the asymptotic normalization coefficient, , and the asymptotic ratio, , from the three electromagnetic form factors of Lithium-6. The fitting to these form factor data yields fm and .</p
Evaluating State-Based Network Dynamics in Anhedonia
No full textAnhedonia refers to the loss of motivation to engage in previously enjoyable activities. While anhedonia is most often characterized as a symptom of psychiatric disorders such as depression, schizophrenia, and post-traumatic stress disorder, it can also present on its own. In spite of this, it is typically overlooked as a primary focus of research studies due to limitations inherent to our current diagnostic system. Therefore, no targeted treatments for anhedonia exist despite the significant impairment it causes. Moreover, very few studies to date have explored underlying neuropsychological characteristics of anhedonia, which is essential to the development of effective treatments for this clinical target. Because anhedonia is a core clinical target spanning many disorders as well as existing as its own disorder, transdiagnostic treatment approaches are of critical scientific importance to improve population mental health.The present study addresses this gap in the literature by taking a graph theoretical approach to characterizing state-based (i.e., reward anticipation, rest) network dynamics in a transdiagnostic sample of adults with clinically significant anhedonia (n = 77). Analyses focused on three canonical brain networks: the Salience Network (SN), the Default Mode Network (DMN) and the Central Executive Network (CEN). Owing to the direct inputs from reward-related regions to the SN, hypotheses centered on anhedonia relating to deficits in connectivity within the SN, as well as between the SN and the other networks.
Two models were tested. First, a multiple linear regression assessed to what extent connectivity within the SN, as well as between the SN and the other two networks (i.e., CEN, DMN) during reward anticipation related to anhedonic symptoms. To build on these findings and assess dynamic state changes as they relate to anhedonia, a second multiple linear regression explored whether the magnitude of topographical reorganization that took place within the SN as well as between the SN and the other two networks predicted anhedonic severity in this sample. Contrary to hypotheses, neither connectivity within the SN or between the SN and the CEN or DMN during reward anticipation, nor reorganization within the SN or between the SN and the CEN or DMN when transitioning from rest to reward anticipation were associated with anhedonia severity in this sample.
Exploratory analyses looked beyond the SN and found a significant association between anhedonia severity and DMN reorganization from rest to reward anticipation. Specifically, greater anhedonia severity was associated with less reorganization in response to reward anticipation. This finding suggests that anhedonia may be associated with DMN hyposensitivity, such that individuals with more severe anhedonia may have a difficult time disengaging from their internal world in the context of potentially rewarding experiences. Very little is known about the internal experience of anhedonia, and future work should focus on examining what internal thought processes these individuals may be having difficulty disengaging from. Nonetheless, an impaired ability to attend to the external world when potential reinforcers are present can prevent individuals from coming into contact with rewarding experiences in their environments and be a key maintaining factor of anhedonia.
Although preliminary, these findings challenges the centrality of the SN in anhedonia and suggests the importance of the DMN. Future studies should aim to replicate this finding and explore potential clinical implications. Specifically, treatments that foster the ability to flexibility redirect attention to the present moment, such as mindfulness-based cognitive therapies, or non-invasive neuromodulatory therapies that target the DMN, may be particularly promising interventions for anhedonia.
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