Anesthetic management of minimally invasive intervention in children's oncohematology: preoperative patient management protocol

Preoperative patient management protocol in the complex anesthetic support of minimally invasive interventions in pediatric oncology is described. Choice of general anesthesia method was determined by the specific clinical situation by analyzing all of the following factors: airway management, necessity and anticipated duration of unconsciousness, the need for analgesia, necessity and duration of immobilization, prevention of hypothermia, the presence and severity of disturbances in the hemostatic system, comfort for the child and his representatives (parents). Basic techniques of child preoperative examination, as well as the methodology for predicting the risk of perioperative adverse events are described.</p

Optimization of Monte-Carlo calculations of the effective potential

We study Monte Carlo calculations of the effective potential for a scalar field theory using three techniques. One of these is a new method proposed and tested for the first time. In each case we extract the renormalised quantities of the theory. The system studied in our calculations is a one component $\phi^4$ model in two dimensions. We apply these methods to both the weak and strong coupling regime. In the weak coupling regime we compare our results for the renormalised quantities with those obtained from two-loop lattice perturbation theory. Our results are verified in the strong coupling regime through comparison with the strong coupling expansion. We conclude that effective potential methods, when suitably chosen, can be accurate tools in calculations of the renormalised parameters of scalar field theories.Comment: 26 pages of LaTeX, uses psfig.sty with 6 figures. Entire manuscript available as a postscript file via WWW at http://www.physics.adelaide.edu.au/theory/papers/ADP-97-13.T250-abs.html or via anonymous ftp at ftp://bragg.physics.adelaide.edu.au/pub/theory/ADP-97-13.T250.p

Probability distribution of magnetization in the one-dimensional Ising model: Effects of boundary conditions

Finite-size scaling functions are investigated both for the mean-square magnetization fluctuations and for the probability distribution of the magnetization in the one-dimensional Ising model. The scaling functions are evaluated in the limit of the temperature going to zero (T -> 0), the size of the system going to infinity (N -> oo) while N[1-tanh(J/k_BT)] is kept finite (J being the nearest neighbor coupling). Exact calculations using various boundary conditions (periodic, antiperiodic, free, block) demonstrate explicitly how the scaling functions depend on the boundary conditions. We also show that the block (small part of a large system) magnetization distribution results are identical to those obtained for free boundary conditions.Comment: 8 pages, 5 figure

Выбор препарата инфузионной терапии в раннем послеоперационном периоде у детей

The choice of drug for initial fluid therapy in the early postoperative period is important in terms of clinical efficacy and cost-effectiveness of the combination treatment.The aim of the study was to compare the effects of a succinate-containing solution and 0.9% NaCl solution when used as a drug of initial intravenous fluid therapy in early postoperative period in children.Materials and methods. A prospective randomized trial was conducted with participation of 43 patients having ASA II—III score after elective surgical interventions with a duration of 1-3 hours. In Group I («N») (n=23) the patients received continuous infusion of 0.9% NaCl solution in the early postoperative period (within 3 hours after the operation), in Group 2 («R») (n=20) continuous infusion of a succinate-containing solution was administered in 2.3 (1.6; 2.8) mode. The inter- and intragroup differences during the study were estimated by the changes of water-electrolyte and acid-base balance, basal metabolism, and phase angle (estimated integral index of cellular membranes condition) values. The data were recorded during the 5 stages of the study: 1 — immediately upon ICU admission (baseline), 2 — 60 minutes, 3 — 90 minutes, 4 — 120 minutes, 5 — 180 minutes after the ICU admission.Results. Significant differences in plasma potassium level between the groups 60 minutes (P=0.01) and 180 minutes (P=0.04) after the initiation of drugs infusion were found. In group N, at the 2nd stage, a 7% decrease in the potassium level was observed, while in group R, it increased by 2.1% as compared with the baseline. By the end of the study, potassium level decreased by 6.9% in group N and by 6.5% in group R. The intragroup differences were significant in Group N at the 2nd (P=0.02) and 5th (P=0.01) stages. In group R, no significant differences vs the baseline were found at any stage. In all cases, the values were within the reference values. In group N, at the 2nd stage the sodium concentration increased compared with the 1st stage by 2.1% (P=0.01). In group R, at the 5th stage, a significant decrease of Cl- concentration by 2.7% (P=0.01) was observed. The acid-base status showed a trend towards mixed acidosis at the 2nd stage in both groups, with the similarly significant pH reduction by 1.3% vs the baseline, whereas at 5th stage the decrease of pH was more significant in Group N (by 1.2% vs the baseline) than in Group R (by 0.9%) (P=0.01). In group N, the phase angle value was found to decrease by 8.6% at the 2nd stage and by 6% at the 5th stage (P=0.01). In group R no significant differences in the phase angle values were found.Conclusion. The succinate-containing solution has more favorable effect on the water-electrolyte and blood acid-base balance, as well as the state of cell membranes compared with the 0.9% NaCl solution.Выбор препарата стартовой инфузионной терапии в раннем послеоперационном периоде актуален с позиции клинической эффективности, определяющей также и экономическую целесообразность комплекса лечебных мероприятий.Цель исследования. Сравнительная оценка сукцинатсодержащего раствора и раствора 0,9% NaCl в качестве препарата стартовой инфузионной терапии в раннем послеоперационном периоде у детей.Материалы и методы. Провели проспективное рандомизированное исследование методом случайной выборки у 43 пациентов с оценкой по ASA II-III после плановых хирургических вмешательств, длительностью 1-3 часа. В 1-й группе «N», (n=23) дети в раннем послеоперационном периоде (в течение 3 ч после операции) получали непрерывную инфузию раствора 0,9% NaCl, во 2-й группе «R», (n=20) — инфузию в режиме 2,3 (1,6; 2,8) сукцинатсодержащим раствором. Межгрупповое и внутригрупповое различие на этапах исследования оценивали по динамике водно-электролитного и кислотно-основного состояния (КОС), основного обмена и значений фазового угла — расчетного интегрального показателя состояния мембран клеточных структур. Данные регистрировали на 5 этапах исследования: 1 — сразу при поступлении в ОРИТ (исходные данные), 2 — через 60 минут, 3 — через 90 минут, 4 — через 120 минут, 5 — через 180 минут от момента поступления в ОРИТ.Результаты. Концентрация калия в плазме крови значимо различалась между группами через 60 (p=0,01) и 180 минут (p=0,04) после начала инфузии препаратов. В группе N на 2-м этапе отмечали снижение показателя на 7%, а в группе R увеличение на 2,1%, по отношению к исходному значению. К концу исследования концентрация калия снижалась в группе N на 6,9% и в группе R — на 6,5%. Внутригрупповые различия были значимы в группе N на 2-м (p=0,02) и 5-м (p=0,01) этапах. В группе R ни на одном этапе не выявили значимых различий от исходных значений. Во всех случаях значения показателя находились в пределах референсных значений. В группе N на 2-м этапе содержание натрия достоверно повышалось от значений 1-го этапа на 2,1% (p=0,01). В группе R на 5-м этапе наблюдали значимое снижение содержания Cl- на 2,7% (p=0,01). Динамика показателей КОС характеризовалась тенденцией к смешанному ацидозу на 2-м этапе в обеих группах, отмечали одинаковое значимое снижение pH на 1,3% от исходного значения, а к 5-у этапу — снижение pH было более выражено в группе N — на 1,2% от исходного значения, в группе R — на 0,9%, соответственно (p=0,01). В группе N выявили снижение значения фазового угла на 8,6% на 2-м этапе и на 6% к 5-у этапу исследования (p=0,01). В группе R значимых различий в динамике значений фазового угла не обнаружили.Заключение. Сукцинатсодержащий раствор благоприятнее влияет на водно-электролитный баланс, КОС плазмы крови, состояние клеточных мембран в сравнении с раствором 0,9% NaCl

Comparative study of an Eden model for the irreversible growth of spins and the equilibrium Ising model

The Magnetic Eden Model (MEM) with ferromagnetic interactions between nearest-neighbor spins is studied in $(d+1)-$dimensional rectangular geometries for $d = 1,2$. In the MEM, magnetic clusters are grown by adding spins at the boundaries of the clusters. The orientation of the added spins depends on both the energetic interaction with already deposited spins and the temperature, through a Boltzmann factor. A numerical Monte Carlo investigation of the MEM has been performed and the results of the simulations have been analyzed using finite-size scaling arguments. As in the case of the Ising model, the MEM in $d = 1$ is non-critical (only exhibits an ordered phase at $T= 0$). In $d = 2$ the MEM exhibits an order-disorder transition of second-order at a finite temperature. Such transition has been characterized in detail and the relevant critical exponents have been determined. These exponents are in agreement (within error bars) with those of the Ising model in 2 dimensions. Further similarities between both models have been found by evaluating the probability distribution of the order parameter, the magnetization and the susceptibility. Results obtained by means of extensive computer simulations allow us to put forward a conjecture which establishes a nontrivial correspondence between the MEM for the irreversible growth of spins and the equilibrium Ising model. This conjecture is certainly a theoretical challenge and its confirmation will contribute to the development of a framework for the study of irreversible growth processes.Comment: 21 pages, 11 figure

Improved high-temperature expansion and critical equation of state of three-dimensional Ising-like systems

High-temperature series are computed for a generalized $3d$ Ising model with arbitrary potential. Two specific ``improved'' potentials (suppressing leading scaling corrections) are selected by Monte Carlo computation. Critical exponents are extracted from high-temperature series specialized to improved potentials, achieving high accuracy; our best estimates are: $\gamma=1.2371(4)$, $\nu=0.63002(23)$, $\alpha=0.1099(7)$, $\eta=0.0364(4)$, $\beta=0.32648(18)$. By the same technique, the coefficients of the small-field expansion for the effective potential (Helmholtz free energy) are computed. These results are applied to the construction of parametric representations of the critical equation of state. A systematic approximation scheme, based on a global stationarity condition, is introduced (the lowest-order approximation reproduces the linear parametric model). This scheme is used for an accurate determination of universal ratios of amplitudes. A comparison with other theoretical and experimental determinations of universal quantities is presented.Comment: 65 pages, 1 figure, revtex. New Monte Carlo data by Hasenbusch enabled us to improve the determination of the critical exponents and of the equation of state. The discussion of several topics was improved and the bibliography was update

Photon and Graviton Mass Limits

Efforts to place limits on deviations from canonical formulations of electromagnetism and gravity have probed length scales increasing dramatically over time.Historically, these studies have passed through three stages: (1) Testing the power in the inverse-square laws of Newton and Coulomb, (2) Seeking a nonzero value for the rest mass of photon or graviton, (3) Considering more degrees of freedom, allowing mass while preserving explicit gauge or general-coordinate invariance. Since our previous review the lower limit on the photon Compton wavelength has improved by four orders of magnitude, to about one astronomical unit, and rapid current progress in astronomy makes further advance likely. For gravity there have been vigorous debates about even the concept of graviton rest mass. Meanwhile there are striking observations of astronomical motions that do not fit Einstein gravity with visible sources. "Cold dark matter" (slow, invisible classical particles) fits well at large scales. "Modified Newtonian dynamics" provides the best phenomenology at galactic scales. Satisfying this phenomenology is a requirement if dark matter, perhaps as invisible classical fields, could be correct here too. "Dark energy" {\it might} be explained by a graviton-mass-like effect, with associated Compton wavelength comparable to the radius of the visible universe. We summarize significant mass limits in a table.Comment: 42 pages Revtex4. This version contains corrections and changes contained in the published version, Rev. Mod. Phys. 82, 939-979 (2010), with a few addition

Renormalized couplings and scaling correction amplitudes in the N-vector spin models on the sc and the bcc lattices

For the classical N-vector model, with arbitrary N, we have computed through order \beta^{17} the high temperature expansions of the second field derivative of the susceptibility \chi_4(N,\beta) on the simple cubic and on the body centered cubic lattices. (The N-vector model is also known as the O(N) symmetric classical spin Heisenberg model or, in quantum field theory, as the lattice O(N) nonlinear sigma model.) By analyzing the expansion of \chi_4(N,\beta) on the two lattices, and by carefully allowing for the corrections to scaling, we obtain updated estimates of the critical parameters and more accurate tests of the hyperscaling relation d\nu(N) +\gamma(N) -2\Delta_4(N)=0 for a range of values of the spin dimensionality N, including N=0 [the self-avoiding walk model], N=1 [the Ising spin 1/2 model], N=2 [the XY model], N=3 [the classical Heisenberg model]. Using the recently extended series for the susceptibility and for the second correlation moment, we also compute the dimensionless renormalized four point coupling constants and some universal ratios of scaling correction amplitudes in fair agreement with recent renormalization group estimates.Comment: 23 pages, latex, no figure

Cluster Hybrid Monte Carlo Simulation Algorithms

We show that addition of Metropolis single spin-flips to the Wolff cluster flipping Monte Carlo procedure leads to a dramatic {\bf increase} in performance for the spin-1/2 Ising model. We also show that adding Wolff cluster flipping to the Metropolis or heat bath algorithms in systems where just cluster flipping is not immediately obvious (such as the spin-3/2 Ising model) can substantially {\bf reduce} the statistical errors of the simulations. A further advantage of these methods is that systematic errors introduced by the use of imperfect random number generation may be largely healed by hybridizing single spin-flips with cluster flipping.Comment: 16 pages, 10 figure