Surgical declarative knowledge learning: concept and acceptability study.

Improving surgical training by means of technology assistance is an important challenge that aims to directly impact surgical quality. Surgical training includes the acquisition of two categories of knowledge: declarative knowledge (i.e. 'knowing what') and procedural knowledge (i.e. 'knowing how'). It is essential to acquire both before performing any particular surgery. There are currently many tools for acquiring procedural knowledge, such as simulators. However, few approaches or tools allow a trainer to formalize and record surgical declarative knowledge, and a trainee to have easy access to it. In this paper, we propose an approach for structuring surgical declarative knowledge according to procedural knowledge and based on surgical process modeling. A dedicated software application has been implemented. We evaluated the concept and the software usability on two procedures with different medical populations: endoscopic third ventriculostomy involving 6 neurosurgeons and preparation of a surgical table for craniotomy involving 4 scrub nurses. The results of both studies show that surgical process models could be a well-adapted approach for structuring and visualizing surgical declarative knowledge. The software application was perceived by neurosurgeons and scrub nurses as an innovative tool for managing and presenting surgical knowledge. The preliminary results show that the feasibility of the proposed approach and the acceptability and usability of the corresponding software. Future experiments will study impact of such an approach on knowledge acquisition.

Optically promoted bipartite atomic entanglement in hybrid metallic carbon nanotube systems.

We study theoretically a pair of spatially separated extrinsic atomic type species (extrinsic atoms, ions, molecules, or semiconductor quantum dots) near a metallic carbon nanotube, that are coupled both directly via the inter-atomic dipole-dipole interactions and indirectly by means of the virtual exchange by resonance plasmon excitations on the nanotube surface. We analyze how the optical preparation of the system by using strong laser pulses affects the formation and evolution of the bipartite atomic entanglement. Despite a large number of possible excitation regimes and evolution pathways, we find a few generic scenarios for the bipartite entanglement evolution and formulate practical recommendations on how to optimize and control the robust bipartite atomic entanglement in hybrid carbon nanotube systems.

Simulation of femtosecond "double-slit" experiments for a chromophore in a dissipative environment.

We performed simulations of the prototypical femtosecond "double-slit" experiment with strong pulsed laser fields for a chromophore in solution. The chromophore is modeled as a system with two electronic levels and a single Franck-Condon active underdamped vibrational mode. All other (intra- and inter-molecular) vibrational modes are accounted for as a thermal bath. The system-bath coupling is treated in a computationally accurate manner using the hierarchy equations of motion approach. The double-slit signal is evaluated numerically exactly without invoking perturbation theory in the matter-field interaction. We show that the strong-pulse double-slit signal consists of a superposition of N-wave-mixing (N = 2, 4, 6...) responses and can be split into population and coherence contributions. The former reveals the dynamics of vibrational wave packets in the ground state and the excited electronic state of the chromophore, while the latter contains information on the dephasing of electronic coherences of the chromophore density matrix. We studied the influence of heat baths with different coupling strengths and memories on the double-slit signal. Our results show that the double-slit experiment performed with strong (nonperturbative) pulses yields substantially more information on the photoinduced dynamics of the chromophore than the weak-pulse experiment, in particular, if the bath-induced dephasings are fast.

[Cardiac surgery in Cameroon. Results at one year of the pilot phase]. / Chirurgie cardiaque au Cameroun. Résultats à un an de la phase pilote.

In the framework of implementation of his national program for control and prevention of cardiovascular diseases, Cameroonian government has set up a cardiac surgery project. We report in this manuscript results of one year follow up of the patients operated during the pilot phase. From September 22 till 26, 2008, 11 patients have been operated in Cameroun. Surgical procedures were 5 mitral mechanic valve replacement, 2 aortic mechanic valve replacement, 1 atrial septal defect closure, 2 pace maker implantation. No intrahospital death was observed. One patient died at 11th month after the operation due to mitral valve thrombosis and attributed to lack of compliance. One patient presented low cardiac output, pneumonia and a pleural effusion. 2 patients presented 2 minor complications consisting of pericarditis and superficial wound infection. The results of the pilot phase of cardiac surgery in Cameroon are effective. However, the sustainability of the program require human, material capacity building, and funding mechanism as well.

Calculation of semiclassical free energy differences along nonequilibrium classical trajectories.

We have derived several relations, which allow the evaluation of the system free energy changes in the leading order in variant Planck's over 2pi(2) along classically generated trajectories. The results are formulated in terms of purely classical Hamiltonians and trajectories, so that semiclassical partition functions can be computed, e.g., via classical molecular dynamics simulations. The Hamiltonians, however, contain additional potential-energy terms, which are proportional to variant Planck's over 2pi(2) and are temperature-dependent. We discuss the influence of quantum interference on the nonequilibrium work and problems with unambiguous definition of the semiclassical work operator.

Asymptotic nonequilibrium steady-state operators.

We present a method for the calculation of asymptotic operators for nonequilibrium steady-state quantum systems. The asymptotic steady-state operator is obtained by averaging the corresponding operator in Heisenberg representation over infinitely long time. Several examples are considered to demonstrate the utility of our method. The results obtained within our approach are compared to those obtained within the Schwinger-Keldysh nonequilibrium Green's functions.

Microscopic origin of the jump diffusion model.

The present paper is aimed at studying the microscopic origin of the jump diffusion. Starting from the N-body Liouville equation and making only the assumption that molecular reorientation is overdamped, we derive and solve the new (hereafter generalized diffusion) equation. This is the most general equation which governs orientational relaxation of an equilibrium molecular ensemble in the hindered rotation limit and in the long time limit. The generalized diffusion equation is an extension of the small-angle diffusion equation beyond the impact approximation. We establish the conditions under which the generalized diffusion equation can be identified with the jump diffusion equation, and also discuss the similarities and differences between the two approaches.

Actinomycotic abscess of the anterior abdominal wall: a case report and literature review.

Actinomycosis is a rare, chronic, suppurative, pseudotumoral illness caused by an anaerobic gram positive organism usually Actinomyces israelii which can mimick a tumoral pathology leading to a mutilating surgical resection. We report a case of abdominal actinomycosis and a literature review.

Unified approach to the derivation of work theorems for equilibrium and steady-state, classical and quantum Hamiltonian systems.

We present a unified and simple method for deriving work theorems for classical and quantum Hamiltonian systems, both under equilibrium conditions and in a steady state. Throughout the paper, we adopt the partitioning of the total Hamiltonian into the system part, the bath part, and their coupling. We rederive many equalities which are available in the literature and obtain a number of new equalities for nonequilibrium classical and quantum systems. Our results can be useful for determining partition functions and (generalized) free energies through simulations or measurements performed on nonequilibrium systems.

Structure of neutron-rich Ar isotopes beyond N = 28.

Results from the gamma-ray spectroscopy of {47,48}Ar exemplifying new limits of sensitivity for characterizing neutron-rich nuclei at energies around the Coulomb barrier are presented. The present results, along with interacting shell model calculations, highlight the role of cross-shell excitations and indicate the presence of a nonaxial deformation in 48Ar.

Directed motion and useful work from an isotropic nonequilibrium distribution.

We demonstrate that a gas of classical particles trapped in an external asymmetric potential undergoes a quasiperiodic motion, if the temperature of its initial velocity distribution TNE differs from the equilibrium temperature Teq. The magnitude of the effect is determined by the value of TNE-Teq, and the direction of the motion is determined by the sign of this expression. The "loading" and "unloading" of the gas particles change directions of their motion, thereby creating a possibility of shuttle-like motion. The system works as a Carnot engine where the heat flow between kinetic and potential parts of the nonequilibrium distribution produces the useful work.

Calculations of canonical averages from the grand canonical ensemble.

Grand canonical and canonical ensembles become equivalent in the thermodynamic limit, but when the system size is finite the results obtained in the two ensembles deviate from each other. In many important cases, the canonical ensemble provides an appropriate physical description but it is often much easier to perform the calculations in the corresponding grand canonical ensemble. We present a method to compute averages in the canonical ensemble based on calculations of the expectation values in the grand canonical ensemble. The number of particles, which is fixed in the canonical ensemble, is not necessarily the same as the average number of particles in the grand canonical ensemble.

First measurement of the giant monopole and quadrupole resonances in a short-lived nucleus: 56Ni.

The isoscalar giant monopole resonance (GMR) and giant quadrupole resonance (GQR) have been measured in the 56Ni unstable nucleus by inducing the 56Ni(d,d') reaction at 50A MeV in the Maya active target at the GANIL facility. The GMR and GQR centroids are measured at 19.3+/-0.5 MeV and 16.2+/-0.5 MeV, respectively. The corresponding angular distributions are extracted from 3 degrees to 7 degrees . A multipole decomposition analysis using distorted wave Born approximation with random phase approximation transition densities shows that both the GMR and the GQR exhaust a large fraction of the energy-weighted sum rule. The demonstration of this new method opens a broad range of giant resonance studies at intermediate-energy radioactive beam facilities.

Peripheral cholangiocarcinoma with endoluminal tumor thrombus in main bile duct mimicking a Klatskin tumor.

BACKGROUND: Peripheral cholangiocarcinoma with endobiliary thrombus could be confused with Klatskin tumor, eventually leading to inappropriate therapeutic decision. CASE REPORT: A 56-year-old man presented with an obstructive jaundice. Preoperative magnetic resonance imaging (MRI) showed a segment 7 liver tumor associated with a complete stop at the biliary bifurcation compatible with a Klatskin tumor. Surgical exploration revealed that biliary obstruction was caused by endobiliary tumor-related thrombus. A right hepatectomy was performed, allowing complete endobiliary thrombus extraction. At pathology, a T2N0 intrahepatic cholangiocarcinoma was demonstrated. No adjuvant chemotherapy was given and currently, 22 months after surgery, the patient remains disease free. DISCUSSION: This case underlines the fact that intraductal growth of peripheral cholangiocarcinoma does not represent a contraindication for surgical treatment. MRI could be useful to differentiate such presentation of peripheral cholangiocracinoma from Klatskin tumor and orientate the surgical treatment.

Manifestation of nonequilibrium initial conditions in molecular rotation: the generalized J-diffusion model.

In order to adequately describe molecular rotation far from equilibrium, we have generalized the J-diffusion model by allowing the rotational relaxation rate to be angular momentum dependent. The calculated nonequilibrium rotational correlation functions (CFs) are shown to decay much slower than their equilibrium counterparts, and orientational CFs of hot molecules exhibit coherent behavior, which persists for several rotational periods. As distinct from the results of standard theories, rotational and orientational CFs are found to dependent strongly on the nonequilibrium preparation of the molecular ensemble. We predict the Arrhenius energy dependence of rotational relaxation times and violation of the Hubbard relations for orientational relaxation times. The standard and generalized J-diffusion models are shown to be almost indistinguishable under equilibrium conditions. Far from equilibrium, their predictions may differ dramatically.

Use of marginal donors for liver transplantation: a single-center experience within the Eurotransplant patient-driven allocation system.

BACKGROUND: Due to the organ shortage, marginal donors are increasingly used in liver transplantation (OLT). These grafts may be safely used in less critical recipients but, the real influence of extended donor criteria (EDC) remains uncertain when graft-recipient matching is not applied. Our study analyzed the impact of EDC on initial graft function within the Eurotransplant patient-driven allocation system. PATIENTS AND METHODS: We reviewed 70 OLT performed between 2004 and 2006. The impact of the following EDC were analyzed: age > 60; intensive care unit (ICU) stay > 4 days; peak serum Na(+) > 160 mEq/L; body mass index (BMI) > 30; cardiac arrest with cardiopulmonary resuscitation, and high doses of vasopressors. Early graft function, as defined according to peak transaminase level and spontaneous prothrombin time within the first 5 posttransplant days, was compared between the donors with none or one criterion (group A = 39) and those with >1 criterion (group B = 31). RESULTS: The most frequent EDC were high vasopressor use, ICU stay > 4 days and BMI > 30, were present in respectively 44%, 27%, and 16% of the donors. No EDC were present in 13 donors, one in 26, three in eight, and four in three. Demographics and origin and severity of the liver disease were similar in both groups. We failed to observe significant differences in initial graft function. CONCLUSION: The presence of EDC did not significantly affect early graft function in a population where donor and recipient were not matched. While this observation must be confirmed in a multicenter analysis, it tends to support the use of marginal liver grafts, even in patient-driven allocation systems.

Nissen versus Toupet fundoplication: results of a randomized and multicenter trial.

BACKGROUND: Laparoscopic Toupet fundoplication (TF) is reported to be as effective as Nissen (NF), but to be associated with fewer unfavorable postoperative side-effects. This study evaluates the one- and three-year clinical outcome of 140 randomized patients after a laparoscopic NF or TF. PATIENTS AND METHODS: Inclusion criteria included patients over 16 years old with complications of gastro-oesophageal reflux disease (GORD) and persistence or recurrence of symptoms after three months of treatment. Subjects with a previous history of gastric surgery or repeated fundoplication, brachy-oesophagus or severe abnormal manometry results were excluded. Seventy-seven NF and 63 TF were performed. The severity of symptoms was assessed before and after the procedure. RESULTS: One hundred and twenty-one of the 140 patients after one year, and 118 after three years, were evaluated and no statistically significant clinical difference was observed. The level of satisfaction concerning the outcome of the operation remained high after one or three years regardless of the type of fundoplication performed. CONCLUSIONS: Functional complications after NF are not avoided with TF.

Velocity dependence of friction and Kramers relaxation rates.

We study the influence of the velocity dependence of friction on the escape rate of a Brownian particle from the deep potential well (Eb>>kBT, Eb is the barrier height, kB is the Boltzmann constant, and T is the bath temperature). The bath-induced relaxation is treated within the Rayleigh model (a heavy particle of mass M in the bath of light particles of mass m<

Liver transplantation using non-heart-beating donors: Belgian experience.

UNLABELLED: Mortality on liver transplantation (OLT) waiting lists has increased dramatically. Until recently, non-heart-beating donors (NHBD) were not considered suitable for OLT, because of a higher risk of primary graft nonfunction (PNF) and biliary strictures. However, recent experimental/clinical evidence has indicated that NHBD-OLT is feasible when the period of warm ischemia is short. PURPOSE: To characterize the results of NHBD-OLT in Belgium, a survey was sent to all Belgian OLT centers. RESULTS: Between January 2003 and November 2005, 16 livers originating from NHBD were procured and transplanted. The mean donor age was 48.8 years, including 9 males and 7 females with mean time of stop-therapy to cardiac arrest being 18 minutes and from cardiac arrest to liver cold perfusion, 10.5 minutes. Mean recipient age was 52.2 years including 12 males and 4 females. Mean cold ischemia time was 7 hours 15 minutes. No PNF requiring re-OLT was observed. Mean post-OLT peak transaminase was 2209 IU/L, which was higher among imported versus locally procured grafts. Biliary complications occurred in 6 patients requiring re-OLT (n = 2), endoscopic treatment (n = 2), surgical treatment (n = 1), or left untreated (n = 1). These tended to be more frequent after prolonged warm ischemia. Graft and patient survivals were 62.5% and 81.3%, respectively, with a follow-up of 3 to 36 months. CONCLUSION: This survey showed acceptable graft/patient survivals after NHBD-LT. The NHBD-liver grafts suffered a high rate of ischemic injury and biliary complications and therefore should be used carefully, namely with no additional donor risk factors, lower risk recipients, and short cold/warm ischemia.

A primary peritoneal pseudomyxoma peritonei arising from the Mullerian tissue: a case report.

A primary Pseudomyxoma Peritonei is uncommon. For a long time, ovaries, colon and appendix were proposed like a site origin of these enigmatic lesions. Recent publications show that the majority of cases are due to a rupture of appendicle adenoma. We report a case of a pseudomyxoma peritonei arising in an elderly patient with a previous medical history of appendectomy undergone in infancy. The pseudomyxoma was misdiagnosed as an abdominal abscess related to colitis. In our opinion, metaplasia of the Müllerian system is a possible source of a primary peritoneal pseudomyxoma.