1,812 research outputs found
From Heisenberg matrix mechanics to EBK quantization: theory and first applications
Despite the seminal connection between classical multiply-periodic motion and
Heisenberg matrix mechanics and the massive amount of work done on the
associated problem of semiclassical (EBK) quantization of bound states, we show
that there are, nevertheless, a number of previously unexploited aspects of
this relationship that bear on the quantum-classical correspondence. In
particular, we emphasize a quantum variational principle that implies the
classical variational principle for invariant tori. We also expose the more
indirect connection between commutation relations and quantization of action
variables. With the help of several standard models with one or two degrees of
freedom, we then illustrate how the methods of Heisenberg matrix mechanics
described in this paper may be used to obtain quantum solutions with a modest
increase in effort compared to semiclassical calculations. We also describe and
apply a method for obtaining leading quantum corrections to EBK results.
Finally, we suggest several new or modified applications of EBK quantization.Comment: 37 pages including 3 poscript figures, submitted to Phys. Rev.
Understanding the association between skin involvement and joint activity in patients with psoriatic arthritis: experience from the Corrona Registry.
Objective: To compare the characteristics of patients with psoriatic arthritis among patient groups stratified by degree of skin and joint involvement, and to evaluate the relationship between skin severity and joint activity.
Methods: Body surface area (BSA) and Clinical Disease Activity Index (CDAI) at enrolment were analysed. Patient characteristics were stratified by skin severity and joint activity. Baseline patient characteristics, clinical and disease characteristics and patient-reported outcomes were compared. The strength of the relationship of skin severity and joint activity was evaluated using methods for categorical variables (Ï
Results: 1542 adult patients in the Corrona Psoriatic Arthritis/Spondyloarthritis Registry enrolled between 21 May 2013 and 20 September 2016 were analysed. Most patients in the BSA \u3e3%/CDAI moderate/high subgroup had worse clinical and patient-reported outcomes. A significant (p
Conclusion: Skin severity is modestly correlated with joint activity, and patients with higher skin severity are two times more likely to have increased joint involvement. Clinicians need to address both skin severity and joint activity in treatment decisions
ATP-binding cassette transporter A7 enhances phagocytosis of apoptotic cells and associated ERK signaling in macrophages
The mammalian ATP-binding cassette transporters A1 and A7 (ABCA1 and -A7) show sequence similarity to CED-7, a Caenorhabditis elegans gene that mediates the clearance of apoptotic cells. Using RNA interference or gene targeting, we show that knock down of macrophage ABCA7 but not -A1 results in defective engulfment of apoptotic cells. In response to apoptotic cells, ABCA7 moves to the macrophage cell surface and colocalizes with the low-density lipoprotein receptorârelated protein 1 (LRP1) in phagocytic cups. The cell surface localization of ABCA7 and LRP1 is defective in ABCA7-deficient cells. C1q is an opsonin of apoptotic cells that acts via phagocyte LRP1 to induce extracellular signalâregulated kinase (ERK) signaling. We show that ERK signaling is required for phagocytosis of apoptotic cells and that ERK phosphorylation in response to apoptotic cells or C1q is defective in ABCA7-deficient cells. These studies reveal a major role of ABCA7 and not -A1 in the clearance of apoptotic cells and therefore suggest that ABCA7 is an authentic orthologue of CED-7
A Minimally Replicative HIV-2 Live-Virus Vaccine ProtectsM. nemestrinafrom Disease after HIV-2287Challenge
AbstractM. nemestrinaimmunized with an apathogenic HIV-2 molecular clone (HIV-2KR) were protected from CD4 decline and disease upon challenge with HIV-2287, after any immunizing virus could be detected. Higher but not lower inocula of HIV-2KRwere protective against intravenous inoculation of either 105or 101TCID50of HIV-2287. Protected animals displayed substantial reductions in PBMC proviral burden (1â3 logs), viral titers (1â2 logs), and plasma viral RNA (2â4 logs) compared to unprotected or naive animals as early as 1 week postinfection. Plasma viral RNA became undetectable after 24 weeks in protected animals, but remained high in unprotected animals. No viral RNA was present in the spleen of the protected animal necropsied more than a year after challenge (though viral DNA was still present). No neutralizing responses could be demonstrated, but CTL activity was detected sooner and at higher levels after challenge in protected than in unprotected macaques. In this novel HIV-2 vaccine model, protection was clearly dose-dependent, and clearance of challenge virus RNA from the plasma did not require detectable ongoing replication of the immunizing virus at the time of challenge
Intra-arterial 5-bromo-2-deoxyuridine (BUR) radiosensitization with external beam radiation in rhesus monkeys: A toxicity study
A primate toxicity study was performed to test the hypothesis that BUdR does not increase the likelihood of unilateral or bilateral central nervous system damage secondary to radiation therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45393/1/11060_2004_Article_BF00177431.pd
New-onset atrial fibrillation in patients with worsening heart failure and coronary artery disease:an analysis from the COMMANDER-HF trial
Background:
Atrial fibrillation (AF) in the presence of heart failure (HF) is associated with poor outcomes including a high-risk of stroke and other thromboembolic events. Identifying patients without AF who are at high-risk of developing this arrhythmia has important clinical implications.
Aims:
To develop a risk score to identify HF patients at high risk of developing AF.
Methods:
The COMMANDER-HF trial enrolled 5022 patients with HF and a LVEFââ€â40%, history of coronary artery disease, and absence of AF at baseline (confirmed with an electrocardiogram). Patients were randomized to either rivaroxaban (2.5 mg bid) or placebo. New-onset AF was confirmed by the investigator at study visits.
Results
241 (4.8%) patients developed AF during the follow-up (median 21 months). Older age (â„â65 years), LVEFâ<â35%, history of PCI or CABG, White race, SBPâ<â110 mmHg, and higher BMI (â„â25 kg/m2) were independently associated with risk of new-onset AF, whereas the use of DAPT was associated with a lower risk of new-onset AF. We then built a risk score from these variables (with good accuracy C-indexâ=â0.71) and calibration across observed and predicted tertiles of risk. New-onset AF events rates increased steeply by increasing tertiles of the risk-score. Compared to tertile 1, the risk of new-onset AF was 2.5-fold higher in tertile 2, and 6.3-fold higher in tertile 3. Rivaroxaban had no effect in reducing new-onset AF. In time-updated models, new-onset AF was associated with a higher risk of subsequent all-cause death: HR (95%CI) 1.38 (1.11â1.73).
Conclusions:
A well-calibrated risk-score identified patients at risk of new-onset AF in the COMMANDER-HF trial. Patients who developed AF had a higher risk of subsequent death
Variant R94C in TNNT2âencoded troponin T predisposes to pediatric restrictive dardiomyopathy and sudden death through impaired thin filament relaxation resulting in myocardial diastolic dysfunction
Background Pediatric-onset restrictive cardiomyopathy (RCM) is associated with high mortality, but underlying mechanisms of disease are under investigated. RCM-associated diastolic dysfunction secondary to variants i
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Understanding ownership of patient care: A dual-site qualitative study of faculty and residents from medicine and psychiatry
Introduction: With changes in duty hours and supervision requirements, educators have raised concerns about erosion of patient care ownership by resident physicians. However, the definition of ownership is unclear. This qualitative study investigated definitions of ownership in medicine and psychiatry faculty and residents. Methods: The authors distributed an anonymous online survey regarding definitions of ownership to faculty and residents at the psychiatry and internal medicine residency programs at the University of Washington and the Harvard Longwood psychiatry residency and conducted a qualitative analysis of free-text responses to identify emergent themes. Results: 225 faculty (48.6%) and 131 residents (43.8%) across the three programs responded. Responses yielded themes in five domains: Physician Actions, Physician Attitudes, Physician Identity, Physician Qualities, and Quality of Patient Care. All groups identified themes of advocacy, communication and care coordination, decision-making, follow through, knowledge, leadership, attitudes of going âabove and beyondâ and âthe buck stops hereâ, responsibility, serving as primary provider, demonstrating initiative, and providing the best care as central to ownership. Residents and faculty had differing perspectives on âshift workâ and transitions of care and on resident decision-making as elements of ownership. Discussion This study expanded and enriched the definition of patient care ownership. There were more similarities than differences across groups, a reassuring finding for those concerned about a decreasing understanding of ownership in trainees. Findings regarding shared values, shift work, and the decision-making role can inform educators in setting clear expectations and fostering ownership despite changing educational and care models
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