bluuebunny/crossref_metadata_2025 huggingface dataset:
Dressed‐particle formulation of Brownian motion
Authors: Ordonez Gonzalo , Kim Sungyun
Published: March 2004

We consider a simple model of a classical harmonic oscillator coupled to a field. In standard approaches Langevin‐type equations for bare particles are derived from Hamiltonian dynamics. These equations contain memory terms and are time‐reversal invariant. In contrast, the phenomenological Langevin equations have no memory terms (they are Markovian equations) and give a time evolution split in two branches (semigroups), each of which breaks time symmetry. A standard approach to bridge dynamics with phenomenology is to consider the Markovian approximation of the former. In the current article, we present a formulation in terms of dressed particles, which gives exact Markovian equations. We formulate dressed particles for Poincaré nonintegrable systems, through an invertible transformation operator Λ introduced by Prigogine and collaborators. Λ is obtained by an extension of the canonical (unitary) transformation operator U that eliminates interactions for integrable systems. Our extension is based on the removal of divergences due to Poincaré resonances, which breaks time symmetry. The unitarity of U is extended to “star unitarity” for Λ. We show that Λ‐transformed variables have the same time evolution as stochastic variables obeying Langevin equations and that Λ‐transformed distribution functions satisfy an exact Fokker–Planck equation. The effects of Gaussian white noise are obtained by the nondistributive property of Λ with respect to products of dynamical variables. Therefore, our method leads to a direct link between dynamics of Poincaré nonintegrable systems, probability, and stochasticity. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Control of decoherence: Dynamical decoupling versus quantum Zeno effect: A case study for trapped ions
Authors: Tasaki S. , Tokuse A. , Facchi P. , Pascazio S.
Published: March 2004

The control of thermal decoherence via dynamical decoupling and via the quantum Zeno effect (Zeno control) is investigated for a model of trapped ion, where the dynamics of two low‐lying hyperfine states undergoes decoherence due to the thermal interaction with an excited state. Dynamical decoupling is a procedure that consists in periodically driving the excited state, while the Zeno control consists in frequently measuring it. When the control frequency is high enough, decoherence is shown to be suppressed. Otherwise, both controls may accelerate decoherence. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Spatial bistability: A chemical idiosyncrasy?
Authors: Borckmans P. , Benyaich K. , Dewel G.
Published: March 2004

Spatial reactors allow the study of the true asymptotic states of dissipative structures in autocatalytic chemical systems in solution. They have permitted the experimental discovery of genuine Turing patterns. However, when reactions at work exhibit bistability between homogeneous steady states in a continuously stirred tank reactor, Turing structures remain elusive. A reason may lie in the existence for such reactions of the phenomenon of spatial bistability. A simple model for this effect is discussed here. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
A spoken dialogue system for document information retrieval utilizing topic knowledge
Authors: Kiriyama Shinya , Hirose Keikichi , Minematsu Nobuaki
Published: March 2004

The authors implemented a mechanism for using retrieval field information to promote efficient searching in a spoken dialogue system for document information retrieval tasks. The research focused mainly on the following two points: (1) correctly categorizing the documents in the database into target topics and (2) properly using topic knowledge to promote efficient searching. For point (1), the authors proposed a technique for recursively calculating the relevance score between (retrieval) words and topics (RSW) and the relevance score between documents and topics (RSD). A maximum topic categorization rate of 86.1% was obtained as a result of experimental investigations. An improvement of 5.0% from the initial value (81.1%) due to the recursive calculations showed the effectiveness of the proposed technique. Subjective evaluations were also used to verify the effectiveness of the relevance scores obtained by the proposed technique during practical use. For point (2), the authors compared the proposed system with a system that does not use topic knowledge when the retrieval field was estimated to advance the dialogue. It was apparent that the proposed system could decrease the number of retrieval dialogue interactions and the dialogue interaction period by approximately 20%, which showed the effectiveness of using topic knowledge for aiding efficient searching. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(5): 67–82, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10370
Scheduling for broadcast operation in heterogeneous parallel computing environments
Authors: Ooshita Fukuhito , Matsumae Susumu , Masuzawa Toshimitsu , Tokura Nobuki
Published: March 2004

Parallel computing utilizes heterogeneous parallel computing environments in which multiple processors of various kinds are connected by communication links. Efficient collective communication operations are needed to realize efficient parallel computing in parallel computing environments. Although methods for realizing efficient collective communication operations have previously been proposed for homogeneous parallel computing environments, these methods applied as they are to heterogeneous parallel computing environments cannot realize efficient collective communication operations. In this paper, we consider design of an efficient broadcast, which is one of the most important collective communication operations. We show that we can extend the known sufficient condition for Fastest‐Node‐First (FNF) to output an optimal schedule, where FNF is an efficient heuristic algorithm for the broadcast. We show that we can reduce the time cost of the branch‐and‐bound search for the optimal schedule. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(5): 44–54, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10533
Structural optimization by genetic algorithm with degeneration (GAd)
Authors: Takahama Tetsuyuki , Sakai Setsuko , Ichimura Takumi , Isomichi Yoshinori
Published: March 2004

Genetic Algorithms (GAs) are models of biological evolution. But the concept of degeneration had not previously been introduced to GA. Degeneration is the evolutionary decline or loss of a function or characteristic, and it had not been thought that degeneration could be used for optimization. In this paper, GA with degeneration (GAd), which introduces the concept of degeneration to GA, is proposed. It is assumed that damaged genes and irreversible mutations cause degeneration and that if degeneration occurs, some characteristics of an individual are lost. If the characteristics are regarded as parameters in a model, the number of parameters can be reduced and the optimal parameter structure can be discovered. It is shown that the optimal parameter structure of some models such as neural networks can be discovered by GAd. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(5): 32–43, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10552
Constrained optimization by α constrained genetic algorithm (αGA)
Authors: Takahama Tetsuyuki , Sakai Setsuko
Published: March 2004

In this study, α constrained genetic algorithm (αGA) which solves constrained optimization problems is proposed. Constrained optimization problems, where the objective functions are minimized under given constraints, are very important and frequently appear in the real world. Recently, researches on constrained optimization using genetic algorithm (GA) have been widely carried out, and their results are equivalent to those by existing mathematical methods. αGA is a method which combines the α constrained method with GA. In the α constrained method, the satisfaction level of constraints to express how much a search point satisfies the constraints is introduced. The α level comparison which compares the search points based on the satisfaction level of constraints is also introduced. The α constrained method can convert constrained problems to unconstrained problems using α level comparison. In αGA, the individuals who satisfy the constraints will evolve to optimize the objective function and the individuals who do not satisfy the constraints will evolve to satisfy the constraints, naturally. In this paper, the effectiveness of αGA is shown by comparing αGA with GENOCOP 5.0 on various types of test problems, such as a linear programming problem, nonlinear programming problems, and problems with nonconvex constraints. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(5): 11–22, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10562
Geotensity constraint for 3D surface reconstruction
Authors: Maki Atsuto , Watanabe Mutsumi , Wiles Charles
Published: March 2004

This paper is about automatically reconstructing the full 3D surface of an object observed in motion by a single static camera. Based on the two paradigms, structure from motion and linear intensity subspaces, we introduce thegeotensity constraintthat governs the relationship between four or more images of a moving object, and argue that the constraint is more valid under object motion than the conventional one of constant brightness. We first show that it is possible in theory to solve for 3D surface structure for the case of a single point light source. We then propose to adapt the geotensity constraint to the case of multiple point light sources by mathematically segmenting the illumination space into multiple subspaces. The surface may or may not be textured. The theoretical propositions are investigated through experiments using both real and synthetic images. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(4): 72–83, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1233
A dispersed ethnic group as a living system: Soviet Jewry in the 1970s
Authors: Riss Ilan
Published: March 2004

This paper applies the living systems theory (LST), developed by J. G. Miller, to the analysis of a dispersed ethnic community. The LST structure, in all 20 of its subsystems, is analyzed at a community level for the Jewish population of the USSR in the 1970s. It is found that the thorough definition of all 20 subsystems may help in examining of the organization of ethnic communities. Possible ways of quantifying the subsystems and the use of this method for comparative analysis of various ethnic communities are proposed. Crucial subsystems, the dysfunction of which may threaten the very existence of the ethnic community, are defined. Copyright © 2002 John Wiley & Sons, Ltd.
Toward system principles: general system theory and the alternative approach
Authors: Dubrovsky Vitaly
Published: March 2004

General System Theory (GST) sets its goal as unification of science, and its subject matter as formulation of general system principles, or principles applicable to all systems. Unfortunately, no such principles have been formulated to date. This paper demonstrates that GST is incapable of formulating system principles due to its naturalistic methods and realist ontology that represents system as a real object, or thing. This paper suggests an alternative approach to development of system principles based on the assumption that the purpose of the system approach is not unification of science but dealing with complexity, and the corresponding method is analysis–synthesis. According to this approach, reality is neither systemic nor non‐systemic, and only our methods of treating real objects and corresponding representations of them are either systemic or not. The paper asserts that system science cannot study real systems, because they do not exist. Instead it should study history of system reasoning as the process of development of system principles. As a preliminary step, by analyzing classical definitions of system, this paper identifies the principal system concepts and categorical oppositions that can be used as an initial framework for empirical studies of system reasoning. It also outlines methodology for such studies. Copyright © 2004 John Wiley & Sons, Ltd.
Noninvasive assessment of liver detoxification capacity of children, observed in children from heavily polluted industrial and clean control areas, together with assessments of air pollution and chloro‐organic body burden
Authors: Herbarth Olf , Franck Ulrich , Krumbiegel Peter , Rehwagen Martina , Rolle‐Kampczyk Ulrike , Weiß Holger
Published: March 2004

The liver is an important target organ in exposure to foreign substances or their metabolites. Early changes in the metabolic capacity of the liver may be a first sign of the effect of an exposure and an indication of an early (pre)pathological process. For the noninvasive testing of this metabolic capacity, a special diagnostic tool has been developed and demonstrated under real exposure conditions. The main questions investigated were (1) whether the liver detoxification capacity of children is affected by long‐term low exposure in a highly polluted area and (2) to what extent redevelopment in once heavily polluted industrial areas contributes to improvement in the health measured in the children from the changed detoxification capacity. Kindergarten children from a heavily polluted industrial area and a control area were observed over a prolonged period during redevelopment of the industrial area. The liver's detoxification capacity was assessed with a stable‐isotope‐based diagnostic test, the [15N]methacetin test. In addition, the region‐specific external exposure (indicator components were chlorinated compounds) and internal load were measured. The difference in the children's internal load between the exposed and control groups reflected the differences in exposure (exposed children had an internal load 2.3 times greater than that of the control children). The exposed children showed a 6% lower liver detoxification capacity. A reduction in pollution by about 70% as a result of remediation was reflected in improved liver detoxification capacity, and the difference between the polluted and control areas was no longer significant. Prolonged exposure to low concentrations of xenobiotics can disturb hepatic functioning. The proposed test can be used as a tool to determine the effects of multicomponent exposure and is well suited for bioeffect monitoring. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 103–108, 2004
Seawater quality along the Adriatic coast, Croatia, based on toxicity data
Authors: Bihari Nevenka , Mičić Milena , Fafandel Maja
Published: March 2004

The potential toxicity of organic extracts from 12 seawater samples from each of 24 sampling sites, collected during 1999–2001 along the Adriatic coast, Croatia, was analyzed with the Microtox toxicity bioassay. The results were consistent with the usefulness of Microtox for the detection of accidental toxic events. To determine the water quality of selected areas, cluster analysis for discrimination between groups with similar toxicity load and water quality index as a base for the ranking of sampling sites was introduced. Based on our experimental data, five classes of the quality index were defined, and so areas were ranked in five categories (excellent, good, fair, poor, and very poor) according to their potential toxic influence. The water quality of selected sites for the potential toxicity of organic extracts could be described as excellent at one sampling site, good at 15 sampling sites, and fair at eight sampling sites. Poor and very poor seawater quality was not detected. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 109–114, 2004.
Effects of the herbicide hexazinone on nutrient cycling in a low‐pH blueberry soil
Authors: Vienneau D. M. , Sullivan C. A. , House S. K. , Stratton G. W.
Published: March 2004

The herbicide hexazinone was applied as the commercial formulation Velpar® L at field‐rate (FR) concentrations of FR (14.77 μg ai g−1), FR×5 (73.85 μg ai g−1), FR×10 (147.70 μg ai g−1), FR×50 (738.50 μg ai g−1), and FR×100 (1477.00 μg ai g−1) to acidic soil, pH 4.12, taken from a lowbush blueberry field. Hexazinone was tested for inhibitory effects on various transformations of the nitrogen cycle and soil respiration. Nitrogen fixation was unaffected by hexazinone levels up to FR×100 following a 4‐week incubation period. Ammonification was initially inhibited by all levels of hexazinone, but after 4 weeks, ammonification in all treatment systems was equal to or greater than the control. Nitrification was more sensitive to hexazinone; however, application at a field‐rate level caused no inhibition. Inhibitory effects were noted above FR after a 2‐month endpoint analysis and above FR×5 after a 6‐month endpoint analysis. Hexazinone concentrations up to and including FR×100 stimulated denitrification. Soil respiration was also stimulated over a 3‐week period when applied at a level up to 100 times the recommended field rate. In general, it was found that when applied at the recommended field application rate, hexazinone does not adversely affect the nitrogen cycle or soil respiration in acidic lowbush blueberry soils. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 115–122, 2004
Marine toxin okadaic acid induces aneuploidy in CHO‐K1 cells in presence of rat liver postmitochondrial fraction, revealed by cytokinesis‐block micronucleus assay coupled to FISH
Authors: Le Hégarat Ludovic , Fessard Valérie , Poul Jean Michel , Dragacci Sylviane , Sanders Pascal
Published: March 2004

Okadaic acid (OA), a major polyether toxin involved in diarrhetic shellfish poisoning (DSP), is a potent tumor promoter in rodent skin and glandular stomach and a specific inhibitor of the serine/threonine protein phosphatases PP1 and PP2A. A previous study, which used the cytokinesis‐block micronucleus (CBMN) assay in CHO‐K1 cells, showed that OA induced chromosome damage in the presence of a rat liver metabolic activation system (S9). To support OA biotransformation by S9, the same test system was performed, and DNA damage induced by OA was measured with and without metabolic activation as well as in the presence of heat‐inactivated S9 fraction. The results showed that only in the presence of active S9 did OA significantly increased the frequency of micronucleated binucleated (MNBN) cells. After a 4‐h treatment a 2‐ to 5‐fold increase of MNBN cells was observed at 30 nM and at 50 nM of OA. However, without S9 or in the presence of heat‐inactivated S9, OA did not induce any chromosome damage. We concluded that OA can be metabolically activated in vitro into metabolites that are more genotoxic. The CBMN assay coupled with fluorescence in situ hybridization (FISH) using a DNA probe for centromere detection was performed to discriminate between clastogenic (chromosome breakage) and aneugenic (chromosome loss) effects. FISH analysis showed that OA metabolites increased in a dose‐dependent manner in centromere positive micronuclei (CEN+): 60% of CEN+ at 30 nM and 75% of CEN+ at 50 nM of OA. The uptake of OA into CHO‐K1 cells and the biotransformation of the toxin are discussed. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 123–128, 2004
Cytogenetic effects of leachates from tannery solid waste on the somatic cells of Vicia faba
Authors: Chandra Saurabh , Chauhan L. K. S. , Pande P. N. , Gupta S. K.
Published: March 2004

The contamination of surface‐ and groundwater by the leaching of solid wastes generated by industrial activities as a result of water runoff and rainfall is a matter of great concern. The leachates from tannery solid waste (TSW), a major environmental pollutant, were examined for their possible genotoxic effects on the somatic cells of Vicia faba. Leachates were prepared from solid wastes procured from leather‐tanning industrial sites, and V. faba seedlings were exposed to three test concentrations, 2.5%, 5%, and 10%, through soil and aqueous media for 5 days. The root tips examined for cytogenetic damage revealed that leachate of TSW significantly inhibited the mitotic index and induced significantly frequent chromosomal and mitotic aberrations (CA/MA) in a dose‐dependent manner. The chemical analysis of TSW samples revealed that the chief constituents were chromium and nickel, which may cause genetic abnormalities. The frequency of aberrations was found to be higher in the root meristematic cells of Vicia faba exposed through the aqueous medium than those exposed through the soil medium. The results of the present study indicated that contamination of potable water bodies by leachates of TSW may cause genotoxicity. For the biomonitoring of complex mixtures of toxicants with the V. faba bioassay, the use of the aqueous medium seems to be a more promising method than the use of the soil medium. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 129–133, 2004.
Power and cost aware localized routing with guaranteed delivery in unit graph based ad hoc networks
Authors: Stojmenovic Ivan , Datta Susanta
Published: March 2004

In a localized routing algorithm, each node currently holding a message makes forwarding decision solely based on the position information about itself, its neighbors and destination. In a unit graph, two nodes can communicate if and only if the distance between them is no more than the transmission radius, which is the same for each node. This paper proposes localized routing algorithms, aimed at minimizing total power for routing a message or maximizing the total number of routing tasks that a network can perform before a partition. The algorithms are combinations of known greedy power and/or cost aware localized routing algorithms and an algorithm that guarantees delivery. A shortcut procedure is introduced in later algorithm to enhance its performance. Another improvement is to restrict the routing to nodes in a dominating set. These improvements require two‐hop knowledge at each node. The efficiency of proposed algorithms is verified experimentally by comparing their power savings, and the number of routing tasks a network can perform before a node loses all its energy, with the corresponding shortest weighted path algorithms and localized algorithms that use fixed transmission power at each node. Significant energy savings are obtained, and feasibility of applying power and cost‐aware localized schemes is demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
Performance of dead reckoning‐based location service for mobile ad hoc networks
Authors: Kumar Vijay , Das Samir R.
Published: March 2004

A predictive model‐based mobility tracking method, called dead reckoning, is developed for mobile ad hoc networks. It disseminates both location and movement models of mobile nodes in the network so that every node is able to predict or track the movement of every other node with a very low overhead. The basic technique is optimized to use ‘distance effect’, where distant nodes maintain less accurate tracking information to save overheads. The dead reckoning‐based location service mechanism is evaluated against three known location dissemination service protocols: simple, distance routing effect algorithm for mobility (DREAM) and geographic region summary service (GRSS). The evaluation is done with geographic routing as an application. It is observed that dead reckoning significantly outperforms the other protocols in terms of packet delivery fraction. It also maintains low‐control overhead. Its packet delivery performance is only marginally impacted by increasing speed or noise in the mobility model, that affects its predictive ability. Copyright © 2004 John Wiley & Sons, Ltd.
An adaptive hierarchical mobile IPv6 using mobility profile
Authors: Hwang Seung‐Hee , Lee Bo‐Kyung , Han Youn‐Hee , Hwang Chong‐Sun
Published: March 2004

The Hierarchical Mobile IPv6 (HMIPv6), which is based on the Mobile IPv6 (MIPv6), has been proposed by IETF to reduce registration control signaling. It separates micro‐mobility from macro‐mobility with the help of an intermediate mobility agent, called the mobility anchor point (MAP), and exploits a Mobile Node's (MN's) spatial locality. However, all packets from a Correspondent Node (CN) to an MN are delivered through the MAP. That causes delay in packets delivery and the congestion of packets in the MAP so that it results in deterioration of network capability. To alleviate these problems, we propose a Hierarchical Mobile IPv6 protocol using not only spatial locality but also temporal locality. We introduce a profile for management of these locality information. According to the information in the profile, some packets are directly delivered to an MN, if MN seems to reside for a long time in the current subnet. Also, we introduce a handover scheme with the help of an L2 trigger, so that the proposed scheme takes nearly the same handover delay time as HMIPv6. The other contribution of this paper is to suggest a mathematical modeling and analysis of network traffic costs, MAP processing costs and handover latency for both HMIPv6 and the proposed scheme. Copyright © 2004 John Wiley & Sons, Ltd.
Performance evaluation of TCP under dynamic allocation scheme for down‐link transmission rate in W‐CDMA systems
Authors: Fukuda Yutaka , Koga Hiroyuki , Ikenaga Takeshi , Oie Yuji
Published: March 2004

IMT‐2000 has attracted much attention as the Next Generation Mobile Communication System. IMT‐2000 can provide high‐bit‐rate data communication service, so that a great number of packets conveyed by TCP (transmission control protocol) can be transmitted over a wireless link. W‐CDMA, standardized in 3GPP (which standardizes IMT‐2000), allows dynamically allocating transmission rates to flow over a wireless link in response to a changing FER for each flow, which is thought to be essential for a next generation mobile communication system. Therefore, in this paper, we study the characteristics of the dynamic allocation scheme when TCP flows share a wireless link, and, in particular, we focus on the throughput performance of these TCP flows. First, we use simulations to examine the effectiveness of the dynamically allocating down‐link transmission rate for TCP flows in response to changing the frame error rate (FER). Through the simulation results, we will show how it can improve the total throughput performance of TCP flows. Furthermore, we can obtain an effective way to allocate transmission rates to flows with different FERs in order to achieve high total throughput. Finally, we will deal with a case of multiple flows from a fixed host to a mobile host. In actual networks, this often happens. In this case, we will show that the total throughput of TCP flows degrades less than in the single‐flow case, even when the FER is high. Copyright © 2004 John Wiley & Sons, Ltd.
Size/geometry optimization of trusses by the force method and genetic algorithm
Authors: Kaveh A. , Kalatjari V.
Published: March 2004

In this article size/geometry optimization of trusses is performed using the force method and genetic algorithm. A large number of design variables consisting of cross‐sectional areas and nodal coordinates are involved in such an optimization, and due to a large number of constraints, the dimensions of the design space are often numerous and in the case of discrete values for cross sections usually discontinuous. In order to avoid local optima, modified genetic algorithms are developed. Furthermore, the force method is employed to improve the speed of the optimization. In the first phase of the described method, the initial geometry of the truss is fixed and near optimum ranges for the cross‐section areas are obtained using the relationships from the force method. In the second phase, the geometry of the structure is altered with the aim of designing lower‐weight structures. Within the Genetic Algorithm a new dynamic penalty function is defined and a modified process of reproduction is presented. A contraction process is also employed for the design space using shorter substrings for the design variables.
The ASM Refinement Method
Authors: Börger Egon
Published: March 2004

In this paper the abstract state machine (ASM) refinement method is presented. Its characteristics compared to other refinement approaches in the literature are explained. Some frequently occurring forms of ASM refinements are identified and illustrated by examples from the design and verification of architectures and protocols, from the semantics and the implementation of programming languages and from requirements engineering.
Popliteal Aneurysm: Diagnostic Workup and Results of Surgical Treatment
Authors: Harder Yves , Notter Hanspeter , Nussbaumer Peter , Leiser Alfred , Canova Corina , Furrer Markus
Published: March 2004

Untreated popliteal aneurysm (PA) may cause serious complications. Early detection and surgery are beneficial. What are the circumstances under which the diagnosis of PA is made? What risks are associated with the treatment? A total of 36 consecutive PAs in 22 men and 2 women were treated in a single‐center series. Altogether, 26 surgical reconstructions (group 1) were performed using a medial approach, and two PAs were resected through a dorsal approach. Eight patients with eight PAs did not undergo surgery (group 2): Two were awaiting surgery, and six had refused it. At the time of diagnosis, 25 PAs were symptomatic: local pain, swelling, or ”pulsation” in the popliteal groove (29%); claudication of the foot/calf (39%); critical ischemia (21%). Eleven asymptomatic cases were discovered during screening duplex sonography of known aortic aneurysms Among the 28 PAs that underwent surgery, 6 produced acute symptoms. The following complications were observed: five postoperative hematomas, one infected polytetrafluoroethylene (PTFE) graft, two early graft occlusions, and two significant stenoses of the distal anastomosis. After a mean follow‐up of 15 months (range 2‐43 months), group 1 had a limb salvage rate of 100% and a secondary patency rate of 96%. Two patients are still awaiting surgery. Critical ischemia represents an absolute indication for surgical repair, but the observed zero mortality and relatively low morbidity associated with the intervention combined with a favorable patency rate justify the liberal use of surgery even for asymptomatic PAs. The extensible medial approach is preferred. Sequential reconstruction is advised for bilateral PAs.
Pathogenesis of Pain in Chronic Pancreatitis: Ongoing Enigma
Authors: Bornman Philippus C. , Marks Israel N. , Girdwood Andrew W. , Berberat Pascal O. , Gulbinas Antanas , Büchler Markus W.
Published: March 2004

The pathogenesis of pain in chronic pancreatitis remains an enigma. The cause of pain is almost certainly multifactorial and may vary at different stages of the disease process. These factors may include the release of excessive oxygen‐derived free radicals, tissue hypoxia and acidosis, inflammatory infiltration with influx of pain transmittent substances into damaged nerve ends, and the development of pancreatic ductal and tissue fluid hypertension due to morphological changes of the pancreas. Investigations into the causes of pain have been limited by changes in the dynamics with the progression of the disease process, limitations in studying functional and morphological changes of the pancreas in the clinical setting, and the psychosomatic profile of patients. Many of these patients are addicted to alcohol, and suffer from personality disorders. The difficulty in quantifying pain, which is at best subjective, further compounds the issue, especially when assessing the efficacy of treatment.
Endoscopic Retrograde Cholangiopancreatography in Chronic Pancreatitis
Authors: Bolan Peter J. , Fink Aaron S.
Published: March 2004

Endoscopic retrograde cholangiopancreatography (ERCP) plays an important diagnostic and therapeutic role in the management of chronic pancreatitis. New techniques are being developed which should further improve outcomes of endoscopic intervention. The ultimate role of these therapeutic interventions for chronic pancreatitis awaits prospective randomized data demonstrating their efficacy and safety in comparison to surgery. Until such time, these often difficult techniques should be performed by experienced endoscopists with significant experience in pancreatic disease, ideally within the context of controlled clinical trials.
Pancreatoduodenectomy in the Treatment of Chronic Pancreatitis
Authors: Russell R. Christopher G. , Theis Belinda A.
Published: March 2004

The value of surgical resection for patients with chronic pancreatitis has been debated on account of persistent symptoms and the morbidity of the operative procedure, both immediate and delayed. This paper explores the consequence of pancreatoduodenectomy in 175 patients with chronic pancreatitis who were operated on between 1976 and 1997. All patients were carefully selected after varying periods of conservative management. The operation was a classical Kausch‐Whipple resection in 98 patients and a pylorus‐preserving procedure in 67. There were four postoperative deaths (days 7, 10, 35, and 70), and only two reoperations were performed. The median number of postoperative events was one, with delayed gastric emptying being the most common (31 patients). The median length of in‐hospital stay was 20 days (range: 8–215 days), but no patient was discharged until medical and social disabilities were resolved. There were seven late deaths, most of them linked to cigarette smoking and alcohol consumption; 75% of patients had a good clinical outcome, but 18 patients required further pancreatic surgery at a mean of 12 months, either a pancreatojejunostomy or a completion pancreatectomy. Diabetes occurred in 40% of patients by 5 years, and most, at some stage of their postoperative period, required pancreatic enzyme supplementation. It is suggested that resection of the pancreas provides a reasonable life‐style in 75% of patients, but the outcome depends in large part on the predisposing disease.
Pylorus‐preserving Pancreaticoduodenectomy in the Treatment of Chronic Pancreatitis
Authors: Jimenez Ramon E. , Fernandez‐del Castillo Carlos , Rattner David W. , Warshaw Andrew L.
Published: March 2004

The pylorus‐preserving pancreaticoduodenectomy (PPPD) is an alternative to the standard Whipple resection in the treatment of chronic pancreatitis. The operation is safe and can be performed with a low mortality rate. The most common early complication is delayed gastric emptying, which occurs in 25% to 30% of patients, and generally results in longer hospital stays than the standard Whipple procedure. Follow‐up studies show that both operations are equally effective in relieving pain in approximately 75% of selected patients. In the long term, the PPPD successfully preserves physiologic gastric emptying, but at the cost of a higher marginal ulceration rate. The purported nutritional advantages of the PPPD over the classic Whipple resection have not been clearly established. At present, the PPPD is the procedure of choice for patients with chronic pancreatitis requiring panceraticoduodenectomy. Based on available information, this recommendation appears to arise form the fact that the PPPD is less radical than the regular Whipple procedure, and some surgeons find it technically easier. Our experience fails to show a distinct superiority of the PPPD over the Whipple operation.
Comparison of Local Resection of the Head of the Pancreas Combined with Longitudinal Pancreaticojejunostomy (Frey Procedure) and Duodenum‐Preserving Resection of the Pancreatic Head (Beger Procedure)
Authors: Frey Charles F. , Mayer Kathrin L.
Published: March 2004

The etiology of pain in chronic pancreatitis may be ductal hypertension, increased parenchymal pressure, or neural damage. It is difficult to assess the severity of pain in this patient population, a problem made more challenging by the frequency of narcotic dependency. Therapeutic interventions developed to relieve the pain of chronic pancreatitis include denervation of the pancreas, decompression of the main duct of the pancreas, resection of part or all of the diseased pancreas, and reduction of pancreatic secretion. Operative intervention for patients with chronic pain is indicated when severe pain, complications of pain, or potential malignancy are present. The operations that consistently provide long‐lasting pain relief all have in common resection of all or a portion of the head of the pancreas. Adverse effects on exocrine and endocrine function, nutrition, and quality of life are related to the amount of pancreas resected. The ideal procedure should be easy to perform, have a low morbidity and mortality rate, provide long‐lasting pain relief, and not augment endocrine and exocrine insufficiency. No single operation fulfills this ideal. The local resection of the head of the pancreas combined with longitudinal pancreaticojejunostomy (LR‐LPJ) proposed by Frey and the duodenum‐preserving resection of the head of the pancreas (DPHR) proposed by Beger are discussed. The conceptualization, development, and technique of LR‐LPJ are discussed, and comparisons of patient outcomes are made with the outcomes of other procedures for chronic pancreatitis.
Subtotal Pancreatectomy for Chronic Pancreatitis
Authors: Eckhauser Frederic , Cowles Robert , Colletti Lisa
Published: March 2004

Chronic pancreatitis results when pancreatic structure or function is irreversibly damaged by repeated or ongoing inflammation, regardless of the underlying etiology. Most patients present with medically intractable pain and radiological evidence of diffuse gland involvement. Surgical therapy is directed mainly toward palliation of symptoms, and cure is unusual except when the inflammatory process is limited to a specific segment of the pancreas. Surgical strategy should be individualized on the basis of alterations in pancreatic morphology and duct anatomy. In properly selected patients, duct drainage procedures effectively relieve pain and preserve pancreatic function with low perioperative morbidity and mortality. Extensive distal pancreatectomy is effective in relieving pain, but it can be technically challenging and in general should be limited to patients with small‐duct disease because of severe metabolic consequences. Intraportal islet cell autotransplantation or segmental pancreatic autotransplantation may ameliorate the long‐term effects of insulin‐dependent diabetes, but it will have limited applicability until methods for optimizing and purifying islets are developed and the optimal route and site of islet cell implantation have been identified.
Pancreatic Autotransplantation in Chronic Pancreatitis
Authors: Watkins J. Guillermo , Krebs Alfred , Rossi Ricardo L.
Published: March 2004

The apancreatic state secondary to resective surgery for chronic pancreatitis is associated with a high rate of late morbidity and mortality that is due, in part, to endocrine insufficiency. Resective procedures should, therefore, be used very selectively. Over the last 2 decades we have seen a shift from extensive distal resections to limited proximal resections. This is because of the lowering of the operative mortality of pancreatic head resection and its better results in pain relief, while preserving in situ the body and tail of the gland with its metabolic functions. Islet autotransplantation and segmental pancreatic autotransplantation were introduced in 1977 and 1978, respectively. Over 150 and 25 cases of these operations have been reported, respectively. Both techniques are evolving with a goal to improve results. Procedures placing the graft in the iliac fossa and anastomosing the pancreatic duct to the jejunum are now favored over groin placement and duct occlusion. Islet autotransplants achieve a higher yield of islet cells and decrease the exocrine impurity of the preparation. Both methods can prevent or delay the onset of diabetes mellitus, and when diabetes mellitus does occur, it is frequently easier to manage. The long‐term function of the grafts appears to be dependent on the β‐cell mass available in the diseased pancreas, the loss of cells related to the transplant procedure, and the characteristics of gradual loss of function from the type of transplant used. Although extensive pancreatic resections are occasionally required, the possibility of autotransplantation should be considered in those patients.
Splenic Vein Thrombosis and Gastrointestinal Bleeding in Chronic Pancreatitis
Authors: Weber Sharon M. , Rikkers Layton F.
Published: March 2004

The most common cause of isolated thrombosis of the splenic vein is chronic pancreatitis caused by perivenous inflammation. Although splenic vein thrombosis (SVT) has been reported in up to 45% of patients with chronic pancreatitis, most patients with SVT remain asymptomatic. In those patients with gastrointestinal bleeding secondary to esophageal or gastric varices, the diagnostic test of choice to assess for the presence of SVT is late‐phase celiac angiography. Splenectomy effectively eliminates the collateral outflow and is the treatment of choice. Other underlying pathology, such as pseudocysts, can be treated at the same time.
Cardiac, Aortic, and Pulmonary Arteriopathy in HIV-Infected Children: The Prospective P2C2 HIV Multicenter Study
Authors: Perez-Atayde A.R. , Kearney D.I. , Bricker J.T. , Colan S.D. , Easley K.A. , Kaplan S. , Lai W.W. , Lipshultz S.E. , Moodie D.S. , Sopko G. , Starc T.J. ,   For The PC HIV Study Group
Published: March 2004

Arteriopathy in human immunodeficiency virus (HIV)-infected patients is being increasingly recognized, especially in children. However, few studies have histologically evaluated the coronary arteries in HIV-infected children, and none have systematically assessed the aorta and pulmonary arteries. The coronary arteries, thoracic aorta, and the main and branch pulmonary arteries from the postmortem hearts of 14 HIV-infected children were systematically reviewed for vasculopathic lesions and compared with 14 age-matched controls. Findings from the HIV-infected children were compared with clinical, laboratory, and other postmortem findings. Coronary arteriopathy, seen in seven (50%) of the HIV-infected children, was primarily calcific, and it was associated with decreased CD3 and CD4 peripheral blood counts. Large vessel arteriopathy, seen in 9 (64%) of the 14 HIV-infected children, was primarily centered on the vasa vasorum and consisted mainly of medial hypertrophy and chronic inflammation. Large vessel lesions were associated with increased left ventricular mass z-scores ( P = 0.02), and 78% of patients with large vessel arteriopathy had postmortem cardiomegaly. Coronary and large vessel arteriopathies are common in pediatric HIV-infection and have different clinicopathologic features suggesting different pathogenesis.
Preliminary Study on the Cytoarchitecture of the Human Parabrachial/Kölliker-Fuse Complex, with Reference to Sudden Infant Death Syndrome and Sudden Intrauterine Unexplained Death
Authors: Lavezzi Anna Maria , Ottaviani Giulia , Ballabio Gianmario , Rossi Lino , Matturri Luigi
Published: March 2004

The parabrachial/Kölliker-Fuse complex has been defined, in different animal species, to lie in the dorsolateral part of the pontine tegmentum and to be subdivided into three well-defined regions: the medial parabrachial nucleus, the lateral parabrachial nucleus, and the Kölliker-Fuse nucleus. Experimental studies have shown that the parabrachial/Kölliker-Fuse complex is involved in a variety of functional activities and above all plays an important role in respiratory modulation. In human brainstem, the cytoarchitecture and physiology of this complex have not yet been fully characterized. The aim of the present study was to examine fetal and infant human brainstems in order to define the precise morphology of the three nuclei of the parabrachial/Kölliker-Fuse complex, and to determine whether this nervous center shows morphologic alterations in sudden infant death syndrome (SIDS) and in sudden intrauterine unexplained death (SIUD). In serial sections of 31 brain-stems of subjects aged from 32 gestational wk to 10 months of life, we studied, by morphologic and morphometric analyses, the cytoarchitecture and the extension of the three nuclei of the parabrachial/Kölliker-Fuse complex. All the morphometric parameters were very similar in SIUD and SIDS cases to those of the respective control group, as shown by the absence of significant statistical differences between the two fetus and infant groups. We observed that the features of both the lateral and the medial parabrachial nuclei are largely consistent with those reported in experimental studies. In contrast, the Kölliker-Fuse nucleus appears to be more developed in human beings than in other animal species, showing a greater extension and a more complex structure, as well as subdivision into two subnuclei (compactus and dissipatus).
Lung Pathology in Patients with Congenital Diaphragmatic Hernia Treated with Fetal Surgical Intervention, Including Tracheal Occlusion
Authors: Heerema Amy E. , Rabban Joseph T. , Sydorak Roman M. , Harrison Micheal R. , Jones Kirk D.
Published: March 2004

Fetal intervention for congenital diaphragmatic hernia was developed to lessen the high morbidity and mortality of pulmonary hypoplasia. Lung pathology and morphometry in patients treated with fetal intervention have not been described. We report clinical and autopsy findings, as well as basic lung morphometry in 16 cases of congenital diaphragmatic hernia with fetal intervention (12 cases tracheal occlusion; 4 cases hernia repair), and 19 cases of congenital diaphragmatic hernia without fetal intervention. All patients who underwent fetal intervention were born premature. Lung enlargement with increased lung-to-body weight ratio was observed with fetal tracheal occlusion, accompanied by lower than normal radial alveolar counts and increased alveolar size. Patients treated with tracheal occlusion also had early alveolar development (at 29.8, 30.6, and 30.9 wk postconceptual age) as well as mucous fluid pooling in airways and alveoli. All cases showed severe alveolar septal widening, more extensive in patients without fetal intervention. When grouped by postconceptual age, no statistically significant difference was found between patients with and without fetal intervention with respect to lung-to-body weight ratio, radial alveolar count, mean alveolar length, and relative arteriolar media thickness. Lung enlargement has been observed with fetal tracheal occlusion sonographically; our studies suggest that this is due in part to emphysema and mucous fluid pooling. The lung remains abnormal with low radial alveolar counts and increased alveolar size. Tracheal occlusion did not prevent development of lung pathology associated with pulmonary hypoplasia.