The task of quantizing general relativity raises serious questions about the meaning of the present formulation and interpretation of quantum mechanics when applied to so fundamental a structure as the space-time geometry itself. This paper seeks to clarify the foundations of quantum mechanics. It presents a reformulation of quantum theory in a form believed suitable for application to general relativity. The aim is not to deny or contradict the conventional formulation of quantum theory, which has demonstrated its usefulness in an overwhelming variety of problems, but rather to supply a new, more general and complete formulation, from which the conventional interpretation can be deduced. The relationship of this new formulation to the older formulation is therefore that of a metatheory to a theory, that is, it is an underlying theory in which the nature and consistency, as well as the realm of applicability, of the older theory can be investigated and clarified.

"relative State" Formulation of Quantum Mechanics

Advanced Mathematical Methods for Scientists and Engineers

Molecular medicine has led to rapid advances in the characterization of hepatobiliary transport systems that determine the uptake and excretion of bile salts and other biliary constituents in the l...

https://www.physiology.org/doi/pdf/10.1152/physrev.00027.2002

Bile Salt Transporters: Molecular Characterization, Function, and Regulation

Sex differences in parasite infections: Patterns and processes

Fatigue may be described as the decline in the ability of an individual to maintain a level of performance. However, the issue of fatigue in man is complex due to the various physiological and psychological phenomena which contribute to it. This article is limited to a discussion appertaining to that fatigue associated with changes in the physiological processes, and specifically that which is caused by sustained or repeated muscle contractions. It has long been known that during muscle contractions the frequency spectrum of the myoelectric signal undergoes a shift. Recently, several analyses and investigations have been reported on the applicability of this phenomenon for supplying objective or noninvasive measurements of localized muscle fatigue. The essence and results of pertinent publications are discussed with emphasis on the relationship between the spectral shift of the myoelectric signal, conduction velocity of muscle fibers, pH of the interstitial fluid and blood flow within a muscle.

Myoelectrical manifestations of localized muscular fatigue in humans.

Enzymatic elimination of substrates flowing through the intact liver.

Metabolic processes studied by PET are quantified traditionally using compartmental models, which relate the time course of the tracer concentration in tissue to that in arterial blood. For liver studies, the use of arterial input may, however, cause systematic errors to the estimated kinetic parameters, because of ignorance of the dual blood supply from the hepatic artery and the portal vein to the liver. Methods: Six pigs underwent PET after [15O]carbon monoxide inhalation, 3-O-[11C]methylglucose (MG) injection, and [18F]FDG injection. For the glucose scans, PET data were acquired for 90 min. Hepatic arterial and portal venous blood samples and flows were measured during the scan. The dual-input function was calculated as the flow-weighted input. Results: For both MG and FDG, the compartmental analysis using arterial input led to systematic underestimation of the rate constants for rapid blood–tissue exchange. Furthermore, the arterial input led to absurdly low estimates for the extracellular volume compared with the independently measured hepatic blood volume of 0.25 ± 0.01 mL/mL (milliliter blood per milliliter liver tissue). In contrast, the use of a dual-input function provided parameter estimates that were in agreement with liver physiology. Using the dual-input function, the clearances into the liver cells (K1 = 1.11 ± 0.11 mL/min/mL for MG; K1 = 1.07 ± 0.19 mL/min/mL for FDG) were comparable with the liver blood flow (F = 1.02 ± 0.05 mL/min/mL). As required physiologically, the extracellular volumes estimated using the dual-input function were larger than the hepatic blood volume. The linear Gjedde–Patlak analysis produced parameter estimates that were unaffected by the choice of input function, because this analysis was confined to time scales for which the arterial-input and dual-input functions were very similar. Conclusion: Compartmental analysis of MG and FDG kinetics using dynamic PET data requires measurements of dual-input activity concentrations. Using the dual-input function, physiologically reasonable parameter estimates of K1, k2, and Vp were obtained, whereas the use of conventional arterial sampling underestimated these parameters compared with independent measurements of hepatic flow and hepatic blood volume. In contrast, the linear Gjedde–Patlak analysis, being less informative but more robust, gave similar parameter estimates (K, V) with both input functions.

https://jnm.snmjournals.org/content/jnumed/42/5/795.full.pdf

Liver Kinetics of Glucose Analogs Measured in Pigs by PET: Importance of Dual-Input Blood Sampling

https://people.smp.uq.edu.au/TonyBracken/distributed.pdf

Hepatic elimination of flowing substrates: The distributed model

The old query concerning longitudinal waves, which already beset the elastic theory of light, has in our day revived in the form expressed in the title Maxwell's field laws are a singular limiting case in that they admit but transversal waves If this held only in however close an approximation, some fundamental laws of radiation would seem to be affected by a factor $\frac{3}{2}$, on account of the 'third degree of freedom' If so, this would render even Maxwell's theory suspect, for we are loath to accept as an adequate description of nature a limiting case whose predictions differ grossly and discontinuously from those reached by a sufficiently close approach to the limit We show here in the simple, if fictitious, example of an ideal conductor, that by extending Proca's field equations in a plausible fashion to the interior of matter the discontinuity is avoided and the correct factors (not $\frac{3}{2}$ thereof) are already reached with a rest-mass at the upper limit, imposed anyhow by other well-known considerations

Must the photon mass be zero

Three hepatic clearance regimes (flow-limited, general, and enzyme-limited) can be defined from a model of hepatic perfusion-elimination relationships. Substances that can be used for clearance measurements can thus be classified into three categories according to the relation between their kinetic elimination constants (Vmax, Km) and hepatic blood flow. The pathophysiologic and clinical importance of the clearance regimes is discussed with special emphasis on the effect of changes in hepatic blood flow and liver function. The criteria for choosing test substances within each regime are stated. This choice depends on the object of study for a clearance measurement (blood flow, drug elimination, liver function). Only the enzyme-limited clearance regime is suited for direct assessment of quantitative liver function ('true clearance'), while the other regimes depend more or less on blood flow.

Ludvik Bass

Papers

Enzymatic elimination of substrates flowing through the intact liver.

Liver Kinetics of Glucose Analogs Measured in Pigs by PET: Importance of Dual-Input Blood Sampling

Hepatic elimination of flowing substrates: The distributed model

Must the photon mass be zero

The physiologic basis for clearance measurements in hepatology.