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Generalized multipolaron expansion for the spin-boson model: Environmental entanglement and the biased two-state system
No full textWe develop a systematic variational coherent-state expansion for the many-body ground state of the spin-boson model, in which a quantum two-level system is coupled to a continuum of harmonic oscillators. Energetic constraints at the heart of this technique are rationalized in terms of polarons (displacements of the bath states in agreement with classical expectations) and antipolarons (counterdisplacements due to quantum tunneling effects). We present a comprehensive study of the ground-state two-level system population and coherence as a function of tunneling amplitude, dissipation strength, and bias (akin to asymmetry of the double-well potential defining the two-state system). The entanglement among the different environmental modes is investigated by looking at spectroscopic signatures of the bipartite entanglement entropy between a given environmental mode and all the other modes. We observe a drastic change in behavior of this entropy for increasing dissipation, indicative of the entangled nature of the environmental states. In addition, the entropy spreads over a large energy range at strong dissipation, a testimony to the wide entanglement window characterizing the underlying Kondo state. Finally, comparisons to accurate numerical renormalization-group calculations and to the exact Bethe ansatz solution of the model demonstrate the rapid convergence of our variationally optimized multipolaron expansion, suggesting that it should also be a useful tool for dissipative models of greater complexity, as relevant for numerous systems of interest in quantum physics and chemistry. © 2014 American Physical Society
Impact of occupational characteristics on return to work for employed patients after elective lumbar spine surgery.
No full textBackground contextLow back pain has an immense impact on the US economy. A significant number of patients undergo surgical management in order to regain meaningful functionality in daily life and in the workplace. Return to work (RTW) is a key metric in surgical outcomes, as it has profound implications for both individual patients and the economy at large.PurposeIn this study, we investigated the factors associated with RTW in patients who achieved otherwise favorable outcomes after lumbar spine surgery.Study design/settingThis study retrospectively analyzes prospectively collected data from the lumbar module of national spine registry, the Quality Outcomes Database (QOD).Patient sampleThe lumbar module of QOD includes patients undergoing lumbar surgery for primary stenosis, disc herniation, spondylolisthesis (Grade I) and symptomatic mechanical disc collapse or revision surgery for recurrent same-level disc herniation, pseudarthrosis, and adjacent segment disease. Exclusion criteria included age under 18 years and diagnoses of infection, tumor, or trauma as the cause of lumbar-related pain.Outcome measuresThe outcome of interest for this study was the return to work 12-month after surgery.MethodsThe lumbar module of QOD was queried for patients who were employed at the time of surgery. Good outcomes were defined as patients who had no adverse events (readmissions/complications), had achieved 30% improvement in Oswestry disability index (ODI) and were satisfied (NASS satisfaction) at 3-month post-surgery. Distinct multivariable logistic regression models were fitted with 12-month RTW as outcome for a. overall population and b. the patients with good outcomes. The variables included in the models were age, gender, race, insurance type, education level, occupation type, currently working/on-leave status, workers' compensation, ambulatory status, smoking status, anxiety, depression, symptom duration, number of spinal levels, diabetes, motor deficit, and preoperative back-pain, leg-pain and ODI score.ResultsOf the total 12,435 patients, 10,604 (85.3%) had successful RTW at 1-year postsurgery. Among patients who achieved good surgical outcomes, 605 (7%) failed to RTW. For both the overall and subgroup analysis, older patients had lower odds of RTW. Females had lower odds of RTW compared with males and patients with higher back pain and baseline ODI had lower odds of RTW. Patients with longer duration of symptoms, more physically demanding occupations, worker's compensation claim and those who had short-term disability leave at the time of surgery had lower odds of RTW independent of their good surgical outcomes.ConclusionsThis study identifies certain risk factors for failure to RTW independent of surgical outcomes. Most of these risk factors are occupational; hence, involving the patient's employer in treatment process and setting realistic expectations may help improve the patients' work-related functionality
Postpartum Symptom Clusters in Birthing Individuals
No full textProblem: Many birthing individuals experience postpartum symptoms which are associated with adverse health conditions including long-term weight gain and depression. Postpartum symptoms often occur in clusters (i.e., three or more co-occurring symptoms that are related to each other) which makes it more difficult to manage. To date, research has been focused on individual symptoms which limits our understanding of how postpartum symptom clusters manifest and impact health. Therefore, the purpose of this dissertation was to develop knowledge on postpartum symptom clusters among birthing individuals. One systematic review (Chapter 2) and three quantitative studies (Chapters 3 to 5) were conducted to achieve this purpose.Methods: For the systematic review, five databases were searched to locate articles. Two reviewers performed title/abstract and full-text screening. Article qualities were examined using Standard Quality Assessment Criteria. Key information was extracted and synthesized using a narrative synthesis. For three quantitative studies, secondary data from the Community and Child Health Network study was used. First, latent profile analysis was performed in Chapter 3 to identify subgroups of postpartum women with different postpartum symptom profiles at 6 months postpartum using observed variables (i.e., general stress, posttraumatic stress, postpartum depression, and sleep disturbance-quality and -quantity). Next, in Chapters 3 to 5, associations between the identified symptom profiles and (a) clinical and social determinants of health (SDOH) characteristics and/or (b) maternal health outcomes (i.e., long-term depression, well-being, and allostatic load) were examined using bivariate and multivariate analysis.
Findings: A total of 30 articles were included in the systematic review (Chapter 2). The majority were quantitative and cross-sectional. Factor analysis was the most frequently used. Stress, depression, somatic, and anxiety clusters were the most frequently identified. In Chapter 3, five distinct postpartum symptom profiles were identified which were labeled as Profile 1: Minimum, Profile 2: Highly disturbed sleep quantity, Profile 3: Mild-moderate, Profile 4: High, and Profile 5: High psychological symptoms. Postpartum women in high symptom severity profiles (Profiles 4 and 5) had significantly more early postpartum complications and a history of depression (Chapter 3). Experiences of different social-economic hardships (e.g., discrimination in healthcare settings or food insecurity) also had a significant impact on postpartum symptom profiles (Chapter 4). Furthermore, postpartum women in high symptom severity profiles had significantly higher depression at 18 and 24 months, lower well-being at 24 months, and higher overall allostatic load at 12 months (Chapters 3 and 5).
Conclusion: This dissertation study found that birthing individuals do have complex and unique postpartum symptom cluster experiences and such experiences have a significant impact on their long-term health. Future research and practice should consider providing targeted interventions to optimally manage postpartum symptom clusters and prevent the development of adverse health outcomes. In doing so, it is critical to consider and address comprehensive SDOH from multiple layers of society.</p
Corrigendum to "Paternal cannabis extract exposure in rats: Preconception timing effects on neurobehavioral effects in offspring" [Neurotoxicology 81 (2020) 180-188].
No full textThe authors regret that the type of cannabis extract provided from the NIDA drug supply program was not the same as was ordered. The authors just recently discovered this. The cannabis extract used in this study provided by the NIDA drug Supply Program was a heated cannabis chemical extract rather than a cannabis smoke extract. The content of delta-9-THC in the extract was the same as reported in the article as verified in chemical analysis of the sample from Research Triangle Institute International (see supplemental material). The authors would like to apologise for any inconvenience caused
Thermal conditions of green turtle (Chelonia mydas) nests in the largest rookery in the eastern Mediterranean
No full textClimate change impacts on vertebrates have many implications. The thermal conditions of vertebrates during incubation are known to influence morphological, physiological, and behavioral traits. Thus, incubation temperatures have consequences for ecological and evolutionary processes, and for certain reptiles can determine sex. For oviparous reptiles, information on the thermal environment of nests is often used to estimate sex ratio, metabolic heat, and their effects on hatching success. This critical baseline information is not always available for all species in all regions, hampering our ability to design analyses that could direct future management and conservation actions. Such is the case for green turtles in the Mediterranean, which nest at many different sites but few of which have had their thermal environment documented in detail. We recorded temperature in 225 green turtle nests (between 2009 and 2013) and 12 control sites in the sand (15, 30, and 45 m distance from high tide line between 2010 and 2013) at 75 cm depth at Akyatan beach, Turkey. The mean temperature of the nests ranged from 28.4 to 33.5°C, and those experiencing high temperatures exhibited low hatching success. The observed thermal environment within the nests exhibited a narrow range relative to the control sites, with daily temperature fluctuations in nests ranging from 0.1°C up to 4.5°C. The nest temperature was strongly negatively correlated with incubation duration, while metabolic heating was highest in the last third of the incubation duration, and was significantly correlated to clutch siz
Persistent Bacillus cereus Bacteremia in 3 Persons Who Inject Drugs, San Diego, California, USA.
No full textBacillus cereus is typically considered a blood culture contaminant; however, its presence in blood cultures can indicate true bacteremia. We report 4 episodes of B. cereus bacteremia in 3 persons who inject drugs. Multilocus sequence typing showed that the temporally associated infections were caused by unrelated clones
The comparison of the commonly used surrogates for baseline renal function in acute kidney injury diagnosis and staging.
No full textBackgroundBaseline serum creatinine (SCr) level is frequently not measured in clinical practice. The aim of this study was to investigate the effect of various methods of baseline SCr determination measurement on accuracy of acute kidney injury (AKI) diagnosis in critically ill patients.MethodsThis was a retrospective cohort study. All adult intensive care unit (ICU) patients admitted at a tertiary referral hospital from January 1, 2011 through December 31, 2011, with at least one measured SCr value during ICU stay, were included in this study. The baseline SCr was considered either an admission SCr (SCrADM) or an estimated SCr, using MDRD formula, based on an assumed glomerular filtration rate (GFR) of 75 ml/min/1.73 m(2) (SCrGFR-75). Determination of AKI was based on the KDIGO SCr criterion. Propensity score to predict the likelihood of missing SCr was used to generate a simulated cohort of 3566 patients with baseline outpatient SCr, who had similar characteristics with patients whose outpatient SCr was not available.ResultsOf 7772 patients, 3504 (45.1 %) did not have baseline outpatient SCr. Among patients without baseline outpatient SCr, AKI was detected in 571 (16.3 %) using the SCrADM and 997 (28.4 %) using SCrGFR-75 (p ConclusionsWhen baseline outpatient SCr was not available, using SCrGFR-75 as surrogate for baseline SCr was found to be more sensitive but less specific for AKI diagnosis compared with using SCrADM. This resulted in higher incidence of AKI with larger likelihood of false-positive cases
Compliance Under Pressure: Strategic Bureaucratic Control and Policy Implementation in China
No full textScholars contend that in weak institutional contexts, political leaders rely on informal networks or ad hoc campaigns to push through policies that challenge powerful local interests. My dissertation challenges this conventional view by arguing that top leaders in authoritarian regimes can effectively enhance local policy compliance by improving and adapting formal institutions to different local conditions, with the support of advanced technology and strong political commitment at the top. With a special focus on the central directives of differentiated work priorities and performance evaluation standards in the context of air pollution control in China, I find that a place-based performance evaluation system enables the central government to exert flexible political control over different regions by assigning them varying work priorities that cater to their specific local conditions and changing environment. In addition to the high-powered promotion incentive, I show that disclosing performance rankings creates an additional incentive for local officials to exert effort on future performance improvement, particularly those who appear at the bottom of the rankings. Finally, I argue that aligning local officials’ interests through formal institutions does not always yield desired outcomes, especially during times of political uncertainty. Informal institutions are, however, more effective in motivating local officials to carry out policy tasks because they can provide protection and assurance to officials. I substantiate this claim by examining how patronage networks shape China's local COVID-19 responses. In sum, a combination of formal and informal institutions remains at work in ensuring policy implementation and bureaucratic compliance in authoritarian countries. </p