On the spin dependence of detection times and the nonmeasurability of arrival times.

According to a well-known principle of quantum physics, the statistics of the outcomes of any quantum experiment are governed by a Positive-Operator-Valued Measure (POVM). In particular, for experiments designed to measure a specific physical quantity, like the time of a particle's first arrival at a surface, this principle establishes that if the probability distribution of that quantity does not arise from a POVM, no such experiment exists. Such is the case with the arrival time distributions proposed by Das and Dürr, due to the nature of their spin dependence.

Anesthesiology Resident Knowledge of Transfusion Medicine: Results From the Anesthesiology Transfusion Education Study.

BACKGROUND: Transfusion of blood products is a common practice in anesthesiology. Inadequate transfusion medicine knowledge may lead to inappropriate transfusion practices and patient risk. Using a validated assessment tool modified for anesthesiology, we conducted a survey of anesthesiology residents in the United States to assess transfusion medicine knowledge. METHODS: A validated transfusion medicine examination and accompanying survey were forwarded by program directors to residents for anonymous completion on May 5 and closed on June 30, 2021. The outcome of interest was the mean examination score. Secondary areas of interest were performance by year of training and previous educational experience in transfusion reported by the trainees. Rasch analysis was performed on the examination quality and individual question performance. Kruskal-Wallis H tests were used to identify differences between mean scores. Post hoc comparisons were used to assess specific pairwise differences between mean test scores by survey variable. RESULTS: Four hundred twenty-three anesthesiology residents in 37 programs completed the examination. The mean score was 45.5% ± 12.6%. There was a significant difference in mean cumulative examination scores between different resident training levels (P < 0.001). There was a significant difference in scores between clinical anesthesia (CA)-1 and CA-2 residents (P = 0.011) and CA-1 and CA-3 residents (P = 0.012). No significant difference in examination scores was observed between CA-2 and CA-3 residents (P = 0.95). All these subgroups scored below 50% on the examination. Significant differences between the residency training programs and cumulative scores were identified (P < 0.001). CONCLUSIONS: This examination highlights gaps in transfusion medicine knowledge within US anesthesiology residents. Targeted education may improve knowledge in this area and patient care.

Efficacy of a Point-of-Care Transthoracic Echocardiography Workshop for Medical Students.

OBJECTIVE: To assess the efficacy of a 5-week point-of-care transthoracic echocardiography workshop for medical students. DESIGN: Prospective, time-series design. SETTING: A single institution, including students at one US medical school. PARTICIPANTS: The study comprised eight second- and third-year medical students. INTERVENTIONS: Subjects enrolled in a voluntary educational workshop designed to teach basic point-of-care transthoracic echocardiography. MEASUREMENTS AND MAIN RESULTS: The primary outcome was change on the total examination score (0-100) that assessed hands-on performance of four basic transthoracic echocardiography views, identification of relevant anatomy, and echocardiography knowledge. Secondary outcomes were scores on the practical (0-40) and written (0-60) subsections of the examination. Mean and standard deviation (±SD) total examination scores increased to 83.6 (±5.2) after the workshop versus 54 (±7.1) at baseline (p < 0.0001). Mean (±SD) practical examination scores increased to 38 (±2.5) after the workshop versus 22 (±4.6) at baseline (p < 0.0001). Mean (±SD) written examination scores increased to 46 (±4.8) after the workshop versus 32 (±5.8) at baseline (p = 0.0003). CONCLUSIONS: Results of this pilot study indicated that the workshop curriculum may be an effective way to teach basic point-of-care transthoracic echocardiography to medical students.

Assessment of Didactic Transesophageal Echocardiography Education During Anesthesia Residency.

BACKGROUND: Transesophageal echocardiography can be a useful monitor during noncardiac surgery, in patients with comorbidities and/or undergoing procedures associated with substantial hemodynamic changes. The goal of this study was to investigate if transesophageal-echocardiography-related knowledge could be acquired during anesthesia residency. METHODS: After institutional review board approval, a prospective observational study was performed in two anesthesiology residency programs. After a 41-week didactic transesophageal-echocardiography-education curriculum residents' exam scores were compared to baseline. The educators' examination was validated against the National Board of Echocardiography's Examination of Special Competence in Advanced Perioperative Transesophageal Echocardiography. RESULTS: After the 41-week course, clinical anesthesia (CA)-3 exam scores increased 12% compared to baseline (P = .03), CA-2 scores increased 29% (P = .007), and CA-1 scores increased 25% (P = .002). Pearson correlation coefficient between the educators' exam score and the special competence exam percentile rank was 0.69 (P = .006). Pearson correlation coefficient between the educators' exam score and the special competence exam scaled score was 0.71 (P = .0045). CONCLUSIONS: The 41-week course resulted in significant increases in exam scores in all 3 CA-classes. While didactic knowledge can be learned by anesthesiology residents during training, it requires significant time and effort. It is important to educate residents in echocardiography, to prepare them for board examinations and to care for the increasingly older and sicker patient population. Further work needs to be done to determine optimal methods to provide such education.

Erroneous Activated Coagulation Time During Atrial Flutter Ablation.

When performing left-sided catheter ablation, anticoagulation is used to prevent formation of thrombi that might embolize. After heparin administration, appropriate anticoagulation is confirmed by measuring Activated Coagulation Time (ACT). We report a case during which ACT results were erroneous, and review alternatives to the ACT under such circumstances.

Thermal Equilibrium of a Macroscopic Quantum System in a Pure State.

We consider the notion of thermal equilibrium for an individual closed macroscopic quantum system in a pure state, i.e., described by a wave function. The macroscopic properties in thermal equilibrium of such a system, determined by its wave function, must be the same as those obtained from thermodynamics, e.g., spatial uniformity of temperature and chemical potential. When this is true we say that the system is in macroscopic thermal equilibrium (MATE). Such a system may, however, not be in microscopic thermal equilibrium (MITE). The latter requires that the reduced density matrices of small subsystems be close to those obtained from the microcanonical, equivalently the canonical, ensemble for the whole system. The distinction between MITE and MATE is particularly relevant for systems with many-body localization for which the energy eigenfuctions fail to be in MITE while necessarily most of them, but not all, are in MATE. We note, however, that for generic macroscopic systems, including those with MBL, most wave functions in an energy shell are in both MATE and MITE. For a classical macroscopic system, MATE holds for most phase points on the energy surface, but MITE fails to hold for any phase point.

Can Bohmian mechanics be made relativistic?

In relativistic space-time, Bohmian theories can be formulated by introducing a privileged foliation of space-time. The introduction of such a foliation-as extra absolute space-time structure-would seem to imply a clear violation of Lorentz invariance, and thus a conflict with fundamental relativity. Here, we consider the possibility that, instead of positing it as extra structure, the required foliation could be covariantly determined by the wave function. We argue that this allows for the formulation of Bohmian theories that seem to qualify as fundamentally Lorentz invariant. We conclude with some discussion of whether or not they might also qualify as fundamentally relativistic.

Time scales in the approach to equilibrium of macroscopic quantum systems.

We prove two theorems concerning the time evolution in general isolated quantum systems. The theorems are relevant to the issue of the time scale in the approach to equilibrium. The first theorem shows that there can be pathological situations in which the relaxation takes an extraordinarily long time, while the second theorem shows that one can always choose an equilibrium subspace, the relaxation to which requires only a short time for any initial state.

Approach to thermal equilibrium of macroscopic quantum systems.

We consider an isolated macroscopic quantum system. Let H be a microcanonical "energy shell," i.e., a subspace of the system's Hilbert space spanned by the (finitely) many energy eigenstates with energies between E and E+deltaE . The thermal equilibrium macrostate at energy E corresponds to a subspace H(eq) of H such that dim H(eq)/dim H is close to 1. We say that a system with state vector psi is the element of H is in thermal equilibrium if psi is "close" to H(eq). We show that for "typical" Hamiltonians with given eigenvalues, all initial state vectors psi(0) evolve in such a way that psi(t) is in thermal equilibrium for most times t. This result is closely related to von Neumann's quantum ergodic theorem of 1929.

Canonical typicality.

It is well known that a system weakly coupled to a heat bath is described by the canonical ensemble when the composite S + B is described by the microcanonical ensemble corresponding to a suitable energy shell. This is true for both classical distributions on the phase space and quantum density matrices. Here we show that a much stronger statement holds for quantum systems. Even if the state of the composite corresponds to a single wave function rather than a mixture, the reduced density matrix of the system is canonical, for the overwhelming majority of wave functions in the subspace corresponding to the energy interval encompassed by the microcanonical ensemble. This clarifies, expands, and justifies remarks made by Schrödinger in 1952.

Bohmian mechanics and quantum field theory.

We discuss a recently proposed extension of Bohmian mechanics to quantum field theory. For more or less any regularized quantum field theory there is a corresponding theory of particle motion, which, in particular, ascribes trajectories to the electrons or whatever sort of particles the quantum field theory is about. Corresponding to the nonconservation of the particle number operator in the quantum field theory, the theory describes explicit creation and annihilation events: the world lines for the particles can begin and end.

Pharmacotherapeutic considerations in anesthesia.

This article focuses on new findings leading to improved understanding of the pathophysiology and mechanisms of potential drug interactions between anesthetic drugs or techniques and cardiovascular medications in patients scheduled for surgery. Only the most frequently used drugs are reviewed. Elective surgery provides the luxury to consider these risks and alter therapy accordingly. Under urgent circumstances, however, the increased risks associated with these agents should be anticipated with the goal to minimize adverse effects while maintaining optimal cardiovascular function in the perioperative period.