bluuebunny/crossref_metadata_2025 huggingface dataset:
Antioxidant activities of volatile components isolated from Eucalyptus species
Authors: Lee Kwang‐Geun , Shibamoto Takayuki
Published: September 2002

Extracts of three species of eucalyptus leaves (Eucalyptus polyanthemos Schauer, E globulus Labill and E perriniana) and their major volatile components were assessed for antioxidant activity in two different assays. The inhibitory effect of each extract and its components towards aldehyde/carboxylic acid conversion was measured over a period of 30 days. Their inhibitory effects towards malonaldehyde formation from lipid by oxidation with Fenton's reagent were also measured; the extract from E polyanthemos inhibited the oxidation of hexanal completely for 30 days at a level of 200 and 500 µg ml−1. It also inhibited malonaldehyde (MA) formation in cod liver oil by 86% at the 160 µg ml−1 level. At the 500 µg ml−1 level, thymol, 1,8‐cineole, benzyl alcohol and terpinen‐4‐ol identified in the extract from E polyanthemos reduced the extent of hexanal oxidation over a period of 30 days by 100, 96, 82 and 75% respectively. In the lipid/MA assay, thymol, benzyl alcohol, terpinen‐4‐ol and 1,8‐cineole inhibited MA formation by 80, 63, 58 and 26% respectively at the level of 160 µg ml−1. Thymol exhibited potent antioxidant activity comparable to that of the known natural antioxidant α‐tocopherol.

© 2001 Society of Chemical Industry
The use of multi‐criteria decision analysis to support the search for less conflicting policy options in a multi‐actor context: case study
Authors: Bana E Costa Carlos A.
Published: September 2002

Public resource allocation often requires the management of conflicting objectives of multiple policy actors at different spatial levels. An example is the case study on which this paper is based: the definition of an investment policy in new inter‐municipal road‐links in the Lisbon Metropolitan Region (LMR) for the period 1999–2004. The key regional (inter‐municipal) objective is to choose the sub‐set of proposed road projects that maximizes the quality of LMR's road network for a fixed available budget. Conflict arises, however, if environmental, social and economic impacts at the level of the 18 municipalities involved are significantly unbalanced. This paper describes how multi‐criteria decision analysis' concepts, techniques and software tools were used to analyse spatial conflicts in the LMR case. The study provided the decision‐making body formed by all the municipal mayors with useful information about how much it is necessary to negotiate to reach an agreement on a specific investment policy option. Copyright © 2001 John Wiley & Sons, Ltd.
Experimental anaesthesiologic protocol for porto‐intracaval shunt for liver total vascular exclusion: Preliminary study in the rabbit
Authors: Astuto Marinella , Sorbello Massimiliano , Zirilli Vanessa , Russo Mario , La Greca Gaetano , Di Cataldo Antonio
Published: September 2002

The aim of this study was to evaluate the effects and interference of different anaesthetic techniques in rabbits undergoing liver total vascular exclusion using a porto‐intracaval shunt. Twenty New Zealand rabbits were divided in three groups: group A receiving diazepam as premedication, ketamine + atropine for induction and maintenance of anaesthesia and underoing a porto‐intracaval shunt operation; group B receiving midazolam as premedication, ketamine + fentanyl + atropine for induction and maintenance of anaesthesia and undergoing a porto‐intracaval shunt operation; group C receiving the same drugs as group B but undergoing a simple portal and caval clamping. The following parameters were studied: efficacy of premedication, vital parameters before and after clamping and insertion of the shunt, mean time to clamp and insert the shunt, mean survival time after clamping (group C) or activation of the shunt (groups A and B). Midazolam was significantly better for premedication; there was no statistically significant difference between groups A and B for the vital parameters, for the time necessary to clamp and insert the shunt, for the intraoperative course, and for the mean survival time. The absence of a statistically significant difference between groups could be due to the low number of animals used in the study. There is actually evidence that a correct anaesthesiologic protocol, especially referring to analgesia and fluid management, improves the outcome of operated animals. Surely further studies, possibly conducted on a larger number of animals, are required to evaluate better the results observed and to consider applying these data and this experience to humans.
Spleen autotransplantation in mice: A novel experimental model for immunology study
Authors: Mikó Irén , Bráth Endre , Furka István , Kovács Judit , Kelvin David , Zhong Robert
Published: September 2002

The aim of the experimental model to develop a spleen transplant model in mice to study the role of spleen in autoimmune and transplant rejection. After a midline incision, splenectomy was performed. Four tiny segments were cut from the removed spleen and were rinsed at room temperature in physiological salt solution. The greater omentum was lifted and four omental pockets were created; four thin segments were then placed into the “nests,” subsequently marked, and fixed using 8‐0 suture. The abdomen was then closed. The duration of the survival time was different among the nine groups (n = 3–3). Tissue samples were taken from the marked areas for histological examination stained with hematoxylin and eosin (H&E). H&E staining demonstrated large, well‐circumscribed splenic nests with lymphoid zone and red pulp and well‐formed trabecules in the spleen. Among the possible applications of this novel model is the ability to study the role of spleen in autoimmune and organ rejection.
The use of vein grafts in the treatment of peripheral lymphedemas: Long‐term results
Authors: Campisi Corradino , Boccardo Francesco , Zilli Angelo , Macció Alberto , Napoli Francesco
Published: September 2002

This study evaluates long‐term results of the treatment of peripheral lymphedemas by the microsurgical reconstructive technique of interposed vein grafts. The technique consists of the use of autologous vein grafts to reconstruct lymphatic pathways where there is a block to the lymphatic circulation of the limb, whether of congenital or acquired etiology. The venous segment represents a sort of “bridge” between afferent and efferent lymphatic collectors (lymphatic‐venous‐lymphatic plasty [LVLA]). The results also proved to have positive long‐term effects after microsurgical operation. Follow‐up evaluation was performed clinically by water volumetry and instrumentally by lymphangioscintigraphy. With this LVLA technique, peripheral lymphedemas can be treated when derivative lymphovenous shunts cannot be used because of impaired venous circulation in the same lymphedematous limb. The new aspect of the study is that we report long‐term clinical and instrumental results.
Confocal imaging of Schwann‐cell migration along muscle‐vein combined grafts used to bridge nerve defects in the rat
Authors: Fornaro Michele , Tos Pierluigi , Geuna Stefano , Giacobini‐Robecchi Maria G. , Battiston Bruno
Published: September 2002

Schwann cells guide axonal regrowth during peripheral nerve repair. In a case of a nerve lesion with substance loss, a graft conduit is necessary to enable axons to reach the distal nerve stump. If a non‐nervous autograft is used, the question arises as to the presence and origin of Schwann cells along the grafted tube. We addressed this issue using a tubulization technique based on the use of an autologous vein filled with fresh skeletal muscle for the repair of sciatic nerve defects in the rat. We showed that both ends of the graft were early and progressively colonized by a number of glial fibrillar acid protein–immunopositive and S‐100 immunonegative cells, an immunocytochemical pattern typical of immature Schwann cells. These cells, which were located in the interstice between grafted skeletal muscle fibers, are mainly organized into long chains oriented along the main axis of the graft and progressively colonize all the graft. Schwann cells coming from the distal nerve end are suitable for being responsible for guiding regeneration of nerve fibers along the graft toward the correct periphery (tissue specificity). © 2001 Wiley‐Liss, Inc. MICROSURGERY 21:153–155 2001
Orthotopic liver/small bowel transplantation in rats: A microsurgical model inducing tolerance
Authors: Meyer D. , Thorwarth W.M. , Otto C. , Gassel H.J. , Timmermann W. , Ulrichs K. , Thiede A.
Published: September 2002

Liver cirrhosis in patients with short bowel syndrome is successfully treated in humans by simultaneous liver/small bowel transplantation. However, until now, a clinically relevant experimental rat model for this procedure has not existed. We therefore established a protocol that, for the first time in rats, allows the simultaneous transplantation of arterialized liver and small bowel into an orthotopic position. Short‐term immunosuppression induced not only allograft acceptance but tolerance (as demonstrated by indicator heart/skin transplantation). The immunosuppressive dose required to achieve this result was dramatically less than that of protocols for successful small bowel transplantation alone. Immunohistochemistry detected a transient rejection crisis before tolerance. During this crisis, apoptotic recipient‐type T lymphocytes, mainly CD8+ cells, accumulated in the liver but not in the small bowel allograft. The initiation of T‐cell apoptosis is one possible explanation for the specific immunosuppressive effect of the liver allograft, which also supports the simultaneously transplanted small bowel allograft in our model.
Effectiveness of porto‐intracaval shunt to reduce the negative effects of portal and caval clamping in the rabbit
Authors: La Greca Gaetano , Astuto Marinella , Randazzo Valentina , Latteri Saverio , Lanteri Raffaele , Puleo Stefano
Published: September 2002

In performing experimental liver surgery, it is difficult to prolong anhepatic time because the animals do not tolerate prolonged portal and caval clamping. To counteract prolonged venous stasis, the authors previously developed a simple porto‐intracaval shunt. The shunt consists of a self‐constructed inverted Y silicone tube. The effectiveness of this shunt was studied comparing two groups of 10 rabbits with shunt (S) versus those with clamped portal and inferior caval vein (C). In the group of rabbits that underwent porto‐intracaval shunt, the results concerning intraoperative mortality, intraoperative increase in distal portal vein pressure, and incidence of the histologic signs of gut damage were clearly improved. The proposed porto‐intracaval shunt was therefore effective in reducing some principal negative effects of portal and caval clamping. This type of porto‐intracaval shunt can be therefore useful allowing improvement of experimental models concerning liver surgery in little animals.
Activation of coagulation and fibrinolysis during reconstructive microsurgery in patients with cancer
Authors: Olsson Eija , Svartling Nils , Asko‐Seljavaara Sirpa , Lassila Riitta
Published: September 2002

Cancer patients are subjected to increased systemic risk of thrombotic events and may therefore be at higher risk of even local thrombosis compromising the outcome of reconstructive microsurgery. Coagulation and fibrinolysis activities were studied serially during and after reconstructive microsurgery in seven patients with oropharyngeal cancer or sarcoma in the extremities. A preoperative hypercoagulable state was found in four patients (elevated fibrinogen, TAT, F1+2, or D‐dimer); two of these patients also had a local thrombotic event. In all patients, the plasma markers generally varied perioperatively: fibrinogen decreased, whereas TAT and subsequently D‐dimer increased at the end of the operation. However, tPA and PAI‐1 remained unaltered, except in the patients with thrombosis in whom PAI‐1 activity increased progressively during the operation. F1+2 was also clearly elevated in these two patients at the time of thrombosis. Preoperative assessment of hypercoagulability for this group of patients could be helpful in targeting meticulous antithrombotic protection. © 2001 Wiley‐Liss, Inc. Microsurgery 21:208–213 2001
Nerve regeneration through a healthy peripheral nerve trunk as a nerve conduit: A preliminary study of a new concept in peripheral nerve surgery
Authors: Yüksel Fuat , Ülkür Ersi̇n , Baloğlu Hüseyi̇n , Çeli̇köz Bahatti̇n
Published: September 2002

The popularity of nerve conduits has increased recently due to the need for alternative nerve reconstruction techniques, obviating the harvest of nerve grafts. Based on ideas suggesting nerve tissue itself, which was the most physiologic environment for nerve regeneration, a study using 40 sciatic nerves of 20 rats was performed. The proximal stumps of transected peroneal nerves were sutured to the lateral wall of healthy tibial nerve trunks after removal of the epineurium. Twelve weeks later, tissue samples were taken from the anastomosis sites and from the levels above and below these sites. Configurations of fascicles were evaluated, and numbers of fibers were estimated. It was observed that the fibers of peroneal nerves regenerated into and through the tibial nerve trunk distally. This suggested that active regenerating fibers of a proximal stump of a nerve could regenerate and progress as a fascicular unit in optimum condition at the trunk of another healthy nerve. This preliminary study should stimulate further studies based on this new concept: that a nerve trunk can serve as the host for the regenerating fibers of another nerve. © 2002 Wiley‐Liss, Inc. MICROSURGERY 22:138–143 2002
Improved energetic recovery of skeletal muscle in response to ischemia and reperfusion injury followed by in vivo 31P‐magnetic resonance spectroscopy
Authors: Lundberg Jonas , Lindgård Ann , Elander Anna , Soussi Bassam
Published: September 2002

It is of great clinical interest to improve postischemic tissue recovery during microsurgical transfers. The effect of singlet oxygen energy (SOE) as photon illumination at 634 nm on rat skeletal muscle during ischemia and postischemic reperfusion was investigated noninvasively and continuously by in vivo 31P‐magnetic resonance spectroscopy (31P‐MRS). A model of pedicled rat rectus femoris muscle was used, where phosphorous metabolites were followed before onset of ischemia (control), after 4 h of ischemia, and after 1 h of reperfusion. Two groups were studied: one control group (n = 10), and one SOE‐treated group (n = 10). Blood perfusion was measured by laser Doppler flowmetry (LDF) during the study. After 4 h of ischemia, ATP levels were 72% and 51% of normal control values in the illuminated group and the control group, respectively (P < 0.05). After 1 h of postischemic reperfusion, phosphocreatine (PCr) recovered to 79% and adenosine triphosphate (ATP) to 71% in the illuminated group, whereas in the control group, the recovery was 57% and 51%, respectively (P < 0.05). It is concluded that singlet oxygen energy has a beneficial effect on the energy state of skeletal muscle during ischemia and postischemic reperfusion. © 2002 Wiley‐Liss, Inc. MICROSURGERY 22:158–164 2002
Oscillatory asymptotic expansion for semilinear wave equation
Authors: Pomponio Stefania Di
Published: September 2002

We study oscillatory properties of the solution to semilinear wave equation, assuming oscillatory terms in initial data have sufficiently small amplitude. The main result gives an a priori estimate of the remainder in the approximation by means of the method of geometric optics. The method of establishing this estimate is based on a combination between energy type estimates for transport equation and Sobolev embedding. Copyright © 2001 John Wiley & Sons, Ltd.
Genetic‐algorithm and finite‐element approach to the synthesis of dispersion‐flattened fiber
Authors: Correia Davi , Rodríguez‐Esquerre Vitaly F. , Hernández‐Figueroa Hugo E.
Published: September 2002

A novel numerical approach for the efficient synthesis of dispersion‐flattened fibers is presented. This approach is based on the combination of genetic algorithms and finite elements. Severe constraints, such as a given maximum monochromatic dispersion level and maximum flatness over a desired band, are easily attained. To show the validity and usefulness of our approach, three different profiles are optimized, and their results are compared with published ones. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 245–248, 2001.
Broadband aperture‐coupled T‐shaped microstrip‐fed triangular patch antenna
Authors: Jang Yong‐Woong
Published: September 2002

In this letter, we propose a new structure of an aperture coupled T‐shaped microstrip‐fed triangular patch antenna, which has similar radiation pattern properties, with the advantage of being physically smaller than the aperture‐coupled rectangular patch antenna or microstrip slot antenna, and a bandwidth that is greater than the conventional triangle microstrip antenna. The measured bandwidth was 44.5% (VSWR≤2.0). Experimental results for the radiation pattern and the gain are presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 262–264, 2001.
A low‐profile circularly polarized curl antenna over an electromagnetic bandgap (EBG) surface
Authors: Yang Fan , Rahmat‐Samii Yahya
Published: September 2002

An electromagnetic bandgap (EBG) surface is utilized as a ground plane for a curl antenna to achieve a low‐profile design as well as a circularly polarized pattern. The antenna height is greatly reduced compared to a normal curl antenna over a PEC ground plane. The frequency bandgap and ground plane size are discussed. Experimental results demonstrate the applicability of this concept. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 264–267, 2001.
A procedure to design stacked microstrip patch antennas based on a simple network model
Authors: Anguera J. , Puente C. , Borja C.
Published: September 2002

A stacked patch configuration has been demonstrated experimentally as a feasible solution to enhance the bandwidth of a microstrip antenna, but little information on the design procedure is available. A design scheme based on a simple network model is presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 149–151, 2001.
A convenient and general approach for analyzing NRD‐guide leaky‐wave antennas
Authors: Sheng X. Q. , Yung K. N.
Published: September 2002

In this letter, a convenient and general approach is presented for analyzing nonradiative dielectric (NRD)‐guide leaky‐wave antennas using the finite‐element method (FEM) and perfectly matched layers (PMLs). A typical NRD‐guide leaky‐wave antenna is calculated to confirm the validity of the proposed approach. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 173–175, 2001.
Analysis of random grating period and amplitude errors in ultra‐thin long‐period grating
Authors: Chung Kun‐Wook , Yin Shizhuo
Published: September 2002

The effects of random fabrication errors on an ultra‐thin long‐period grating are numerically investigated. The influences of the random grating period and random amplitude nodes on an optical bandpass filter based on an ultra‐thin long‐period grating are introduced. It is found that the random period errors present severe degradation of the spectral performance of the ultra‐thin long‐period grating. The coupling intensity of the ultra‐thin long‐period grating decays exponentially with even small grating period noises. Our simulation results may help manufacturers to analyze the quality of fabricated long‐period gratings and to point out future improvement directions. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 178–181, 2001.
Patch antenna with switchable slot (PASS): Dual‐frequency operation
Authors: Yang Fan , Rahmat‐Samii Yahya
Published: September 2002

A novel kind of microstrip antenna, a patch antenna with a switchable slot (PASS), is proposed in this paper. A slot is incorporated into the patch, and a p‐i‐n diode is utilized to switch the slot on or off. This antenna can work at dual frequencies with a small and flexible frequency ratio and the same polarization. Experimental results validate this concept. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 165–168, 2001.
E‐plane waveguide filters with partially filled dielectrics for wide bandwidth
Authors: Liu Falin , Xu Shanjia
Published: September 2002

A partially dielectric‐filled waveguide bifurcation structure is proposed to realize wideband bandpass filters. By using modal expansion and matching the tangential fields at the discontinuity, a variational expression for the input admittance is obtained. The Ritz method is used to form a group of linear equations from which the actual admittance can be obtained; then the equivalent‐circuit parameters of the discontinuity are achieved. It is confirmed that the structure is capable of realizing wideband filters. A numerical analysis of a filter example is conducted to justify the validity. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 175–177, 2001.
Leaky‐wave radiation from a grounded dielectric waveguide with finite periodic grooves on a conducting plane
Authors: Lee Cheol Hoon , Cho Young Ki
Published: September 2002

The leaky‐wave radiation problem from a grounded dielectric waveguide with finite conducting periodic grooves of an arbitrary profile is considered. To check the validity of the results for the finite periodic case, an analysis method for the infinite periodic case is also considered for comparison. The analysis method for the finite periodic case is based on a combined FEM (finite‐element method)/MoM (method of moments) procedure, whereas a full MoM procedure is used for the infinite periodic case. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 180–185, 2001.
A systematic method to design single‐patch broadband microstrip patch antennas
Authors: Anguera Jaume , Puente Carles , Borja Carmen , Font Gisela , Soler Jordi
Published: September 2002

A simple electrical network for a single‐layer microstrip patch antenna (SLMPA) and the feeding structure (coaxial probe and compensating capacitor) is proposed to predict the input impedance. The mathematical analysis allows us to design an optimum feed that enhances the impedance bandwidth (BW). © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 185–188, 2001.
An efficient solution of the generalized eigenvalue problems for planar transmission lines
Authors: Prakash V. V. S. , Kuzuoglu Mustafa , Mittra Raj
Published: September 2002

This paper presents an efficient solution for solving the generalized eigenvalue equation arising in the finite‐element (FE) formulation of propagation characterization of planar transmission‐line structures. A two‐dimensional (2‐D) finite‐element method (FEM) is used for analyzing the uniform planar transmission lines. The Arnoldi algorithm is used in conjunction with the multifrontal decomposition of the system matrix for solving the eigensystem. Convergence is typically obtained within a few iterations of the Arnoldi process, and the formulation has proven to be robust, even when dealing with a significantly large number of unknowns. Numerical results are presented for the case of a uniform microstrip line, which clearly show the computational savings resulting from the use of the present approach. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 194–197, 2001.
Efficacy of ifosfamide and doxorubicin given as a phase II “window” in children with newly diagnosed metastatic rhabdomyosarcoma: A report from the Intergroup Rhabdomyosarcoma Study Group*
Authors: Sandler E. , Lyden E. , Ruymann F. , Maurer H. , Wharam M. , Parham D. , Link M. , Crist W.
Published: September 2002

Background

The cure rate for children/adolescents with localized rhabdomyosarcoma (RMS) has tripled over the past 25 years, but patients with metastatic disease at presentation have not benefited similarly, and urgently need new therapy. We evaluated a new drug pair, ifosfamide + doxorubicin, for such patients.

Procedure

We estimated the complete and partial response rates (i.e., CR and PR) of 152 previously untreated children/adolescents with metastatic RMS entered on the IRS‐IV pilot from July 1988 to October 1991 who received an “up‐front window” of ifosfamide (1.8 gm/m2/day for 5 days) and doxorubicin (30 mg/m2/day for 2 days) given every 3 weeks for 12 weeks. This was followed by combination chemotherapy with vincristine, actinomycin D, and cyclophosphamide (VAC), given every 3 weeks for an additional 36 weeks.

Results

Of 115 patients evaluable for early response at 12 weeks, 28 (20%) had CR and 66 (43%) had PR. The ultimate CR rate was 52%. Overall, about one‐third of patients survived. Prognostic factor analysis revealed that patients < 10 years old (P < 0.001), those with embryonal tumors (P = 0.002), or a GU primary site (P = 0.010), and those who lacked nodal disease (P = 0.041), and those who lacked bone or bone marrow metastasis (P < 0.001) fared better than did others.

Conclusions

The 63% CR + PR rate achieved at 12 weeks and overall 5‐year FFS seen with this drug pair is similar to that achieved with previously evaluated drug combinations. We conclude that ifosfamide/doxorubicin is highly active in advanced RMS, and should be considered for inclusion in frontline therapy for children with intermediate or high‐risk RMS. Med Pediatr Oncol 2001;37:442–448. © 2001 Wiley‐Liss, Inc.
Improved accuracy of human cerebral blood perfusion measurements using arterial spin labeling: Accounting for capillary water permeability
Authors: Parkes Laura M. , Tofts Paul S.
Published: September 2002

A two‐compartment exchange model for perfusion quantification using arterial spin labeling (ASL) is presented, which corrects for the assumption that the capillary wall has infinite permeability to water. The model incorporates an extravascular and a blood compartment with the permeability surface area product (PS) of the capillary wall characterizing the passage of water between the compartments. The new model predicts that labeled spins spend longer in the blood compartment before exchange. This makes an accurate blood T1 measurement crucial for perfusion quantification; conversely, the tissue T1 measurement is less important and may be unecessary for pulsed ASL experiments. The model gives up to 62% reduction in perfusion estimate for human imaging at 1.5T compared to the single compartment model. For typical human perfusion rates at 1.5T it can be assumed that the venous outflow signal is negligible. This simplifies the solution, introducing only one more parameter than the single compartment model, PS/vbw, where vbw is the fractional blood water volume per unit volume of tissue. The simplified model produces an improved fit to continuous ASL data collected at varying delay time. The fitting yields reasonable values for perfusion and PS/vbw. Magn Reson Med 48:27–41, 2002. © 2002 Wiley‐Liss, Inc.
Changes in axonal morphology in experimental autoimmune neuritis as studied by high b‐value q‐space 1H and 2H DQF diffusion magnetic resonance spectroscopy
Authors: Assaf Yaniv , Kafri Michal , Shinar Hadassah , Chapman Joab , Korczyn Amos D. , Navon Gil , Cohen Yoram
Published: September 2002

Experimental autoimmune neuritis (EAN) has been studied in rat sciatic nerves by a combination of high b‐value 1H and 2H double quantum filtered (DQF) diffusion MRS. The signal decays of water in the 1H and 2H DQF diffusion MRS were found to be not monoexponential and were analyzed using the q‐space approach. The q‐space analysis of the 1H diffusion data detected two diffusing components, one having broad and the other having narrow displacement profiles. These components were shown to be very sensitive to the progression of EAN disease. The q‐space parameters were found to be abnormal at day 9 postimmunization before the appearance of clinical signs. The assignment of the component with the narrow displacement profile to axonal water has been corroborated by the 2H DQF diffusion MRS results. The displacement and the relative population of this slow and restricted diffusing component followed the processes of demyelination, axonal loss, and remyelination that occur in EAN. The displacements extracted from the slow‐diffusing component with the narrow displacement correlated well with the average size of the axons as deduced from electron microscopy (EM). The component with the broad displacement showed significant changes which were attributed to the formation of endoneurial edema. This observation was also corroborated by the 2H DQF diffusion MRS experiments. It seems, therefore, that q‐space analysis of high b‐values diffusion MRS is a promising new approach for early detection and better characterization of the different pathologies associated with EAN. This study demonstrates the utility of high‐b‐value q‐space diffusion MRS for studying white matter‐associated disorders in general. Magn Reson Med 48:71–81, 2002. © 2002 Wiley‐Liss, Inc.
Coupling and decoupling theory and its application to the MRI phased array
Authors: Lee Ray F. , Giaquinto Randy O. , Hardy Christopher J.
Published: September 2002

In classical MRI phased‐array design, optimal coil overlapping is used to minimize coupling between nearest‐neighbor coils, and low input impedance preamplifiers are used to isolate the relatively weak coupling between non‐nearest neighbors. However, to make the complex sensitivities of phased‐array coils sufficiently distinct in parallel spatially‐encoded MRI, it is desirable to have no overlapping between coils. Also, if phased arrays are used as transmit coils in MRI, one can no longer rely on the low input impedance of the preamplifiers for decoupling. Here a coupling and decoupling theory is introduced to provide a better understanding of the relations between coupled and uncoupled signals in the MRI phased array, and to offer a new method for decoupling phased‐array coils without overlapping the nearest coil pairs. The new decoupling method is based on the assumption that any n‐element phased array can be decoupled by a 2n‐port interface system between phased array and preamplifiers. The detailed analysis and the experimental results show that a four‐port interface can be used to decouple a two‐element phased array. Furthermore, the four‐port interfaces can serve as building blocks to construct a 2n‐port decoupling interface. This new method allows one to place the coil elements anywhere that could optimize parallel spatial encoding without concern for coupling between the coils. The method can also be used for phased‐array transmit coils. Magn Reson Med 48:203–213, 2002. © 2002 Wiley‐Liss, Inc.
Cardiac diffusion MRI without motion effects
Authors: Dou Jiangang , Reese Timothy G. , Tseng Wen‐Yih I. , Wedeen Van J.
Published: September 2002

We present a method for diffusion tensor MRI in the beating heart that is insensitive to cardiac motion and strain. Using a stimulated echo pulse sequence with two electrocardiogram (ECG) triggers, diffusion‐encoding bipolar gradient pulses are applied at identical phases in consecutive cardiac cycles. In this experiment, diffusion is encoded at a single phase in the cardiac cycle of less than 30 ms in duration. This encoding produces no phase shifts for periodic motion and is independent of intervening strains. Studies in a gel phantom with cyclic deformation confirm that by using this sequence we can map the diffusion tensor free of effects of cyclic motion. In normal human subjects, myocardial diffusion eigenvalues measured with the present method showed no significant change between acquisitions encoded at maximum contractile velocity (peak) vs. at myocardial standstill (end‐systole), demonstrating motion independence of in vivo diffusion measurements. Diffusion tensor images acquired with the present method agree with registered data acquired with a previous cardiac diffusion MRI method that was shown to be valid in the normal heart, strongly supporting the validity of MRI diffusion measurement in the beating heart. Myocardial sheet and fiber dynamics measured during systole showed that normal human myocardial sheet orientations tilt toward the radial during systole, and fiber orientations tilt toward the longitudinal, in qualitative agreement with previous invasive studies in canines. These results demonstrate the technique's ability to measure myocardial diffusion accurately at any point in the cardiac cycle free of measurable motion effect, as if the heart were frozen at the point of acquisition. Magn Reson Med 48:105–114, 2002. © 2002 Wiley‐Liss, Inc.
Imaging of intracellular sodium with shift reagent aided 23Na CSI in isolated rat hearts
Authors: Weidensteiner Claudia , Horn Michael , Fekete Elsbeth , Neubauer Stefan , von Kienlin Markus
Published: September 2002

23Na chemical shift imaging (CSI) in conjunction with shift reagents was used to obtain images of intracellular (Nai) and extracellular sodium (Nae) in isolated rat hearts. It was demonstrated that the increase of Nai concentration in ischemic myocardium can be detected with this technique. 3D acquisition‐weighted 23Na CSI datasets with a nominal spatial resolution of 1.7 × 1.7 × 2.9 mm were acquired in 30 min in normoxic hearts and in globally or locally ischemic hearts. The shift reagent Tm(DOTP)5− was used to discriminate Nai and Nae signals. Nai maps could be generated in ischemic hearts, but not in normoxic hearts as the signal‐to‐noise ratio is too low. The Nai signal increased by more than 100% and the Nae signal decreased by more than 50% in myocardium of globally ischemic hearts (n = 3) compared to normoxic hearts (n = 3). In hearts with an acute occlusion of the left anterior descending coronary artery (n = 3), there was a local Nai signal increase in the anterior wall in the range of 60–110% compared to remote, normoxic tissue. Magn Reson Med 48:89–96, 2002. © 2002 Wiley‐Liss, Inc.
Extending the MAD portfolio optimization model to incorporate downside risk aversion
Authors: Michalowski Wojtek , Ogryczak Włodzimierz
Published: September 2002

A mathematical model of portfolio optimization is usually represented as a bicriteria optimization problem where a reasonable tradeoff between expected rate of return and risk is sought. In a classical Markowitz model, the risk is measured by a variance, thus resulting in a quadratic programming model. As an alternative, the MAD model was developed by Konno and Yamazaki, where risk is measured by (mean) absolute deviation instead of a variance. The MAD model is computationally attractive, since it is easily transformed into a linear programming problem. An extension to the MAD model proposed in this paper allows us to measure risk using downside deviations, with the ability to penalize larger downside deviations. Hence, it provides for better modeling of risk averse preferences. The resulting m‐MAD model generates efficient solutions with respect to second degree stochastic dominance, while at the same time preserving the simplicity and linearity of the original MAD model. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 185–200, 2001
Optimal control of an M/G/1 queue with impatient priority customers
Authors: Lillo R.E.
Published: September 2002

An optimal operating policy is characterized for the infinite‐horizon average‐cost case of a single server queueing control problem. The server may be turned on at arrival epochs or off at departure epochs. Two classes of customers, each of them arriving according to an independent Poisson processes, are considered. An arriving 1‐customer enters the system if the server is turned on upon his arrival, or if the server is on and idle. In the former case, the 1‐customer is selected for service ahead of those customers waiting in the system; otherwise he leaves the system immediately. 2‐Customers remain in the system until they complete their service requirements. Under a linear cost structure, this paper shows that a stationary optimal policy exists such that either (1) leaves the server on at all times, or (2) turns the server off when the system is empty. In the latter case, we show that the stationary optimal policy is a threshold strategy, this feature being commonplace in most of priority queueing systems and inventory models. However, the optimal policy in our model is determined by two thresholds instead of one. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 201–209, 2001
Integrated networks that overflow speech and data between component networks
Authors: Lincke‐Salecker Susan , Hood Cynthia S.
Published: September 2002

As cellular networks diversify by expanding the number of services, cell sizes, and generations of technologies supported, it becomes possible to overflow dual‐mode terminals using vertical handovers to other cellular networks or ‘component networks’. This study varies call placement algorithms, by defining, modeling, and evaluating Overflow and Return policies. Copyright © 2002 John Wiley & Sons, Ltd.
A new look at an old visual system: structure and development of the compound eyes and optic ganglia of the brine shrimp artemia salina linnaeus, 1758 (branchiopoda, anostraca)
Authors: Wildt Miriam , Harzsch Steffen
Published: September 2002

Compared to research carried out on decapod crustaceans, the development of the visual system in representatives of the entomostracan crustaceans is poorly understood. However, the structural evolution of the arthropod visual system is an important topic in the new debate on arthropod relationships, and entomostracan crustaceans play a key role in this discussion. Hence, data on structure and ontogeny of the entomostracan visual system are likely to contribute new aspects to our understanding of arthropod phylogeny. Therefore, we explored the proliferation of neuronal stem cells (in vivo incorporation of bromodeoxyuridine) and the developmental expression of synaptic proteins (immunohistochemistry against synapsins) in the developing optic neuropils of the brine shrimp Artemia salina Linnaeus, 1758 (Crustacea, Entomostraca, Branchiopoda, Anostraca) from hatching to adulthood. The morphology of the adult visual system was examined in serial sections of plastic embedded specimens. Our results indicate that the cellular material that gives rise to the visual system (compound eyes and two optic ganglia) is contributed by the mitotic activity of neuronal stem cells that are arranged in three band‐shaped proliferation zones. Synapsin‐like immunoreactivity in the lamina ganglionaris and the medulla externa initiated only after the anlagen of the compound eyes had already formed, suggesting that the emergence of the two optic neuropils lags behind the proliferative action of these stem cells. Neurogenesis in A. salina is compared to similar processes in malacostracan crustaceans and possible phylogenetic implications are discussed. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 117–132, 2002
Development of depolarization‐induced calcium transients in insect glial cells is dependent on the presence of afferent axons
Authors: Lohr Christian , Tucker Eric , Oland Lynne A. , Tolbert Leslie P.
Published: September 2002

Changes in the intracellular Ca2+ concentration ([Ca2+]i) induced by depolarization have been measured in glial cells acutely isolated from antennal lobes of the moth Manduca sexta at different postembryonic developmental stages. Depolarization of the glial cell membrane was elicited by increasing the external K+ concentration from 4 to 25 mM. At midstage 5 and earlier stages, less than 20% of the cells responded to 25 mM K+ (1 min) with a transient increase in [Ca2+]i of approximately 40 nM. One day later, at late stage 5, 68% of the cells responded to 25 mM K+, the amplitude of the [Ca2+]i transients averaging 592 nM. At later stages, all cells responded to 25 mM K+ with [Ca2+]i transients with amplitudes not significantly different from those at late stage 5. In stage 6 glial cells isolated from deafferented antennal lobes, i.e., from antennal lobes chronically deprived of olfactory receptor axons, only 30% of the cells responded with [Ca2+]i transients. The amplitudes of these [Ca2+]i transients averaged 93 nM and were significantly smaller than those in normal stage 6 glial cells. [Ca2+]i transients were greatly reduced in Ca2+‐free, EGTA‐buffered saline, and in the presence of the Ca2+ channel blockers cadmium and verapamil. The results suggest that depolarization of the cell membrane induces Ca2+ influx through voltage‐activated Ca2+ channels into antennal lobe glial cells. The development of the depolarization‐induced Ca2+ transients is rapid between midstage 5 and stage 6, and depends on the presence of afferent axons from the olfactory receptor cells in the antenna. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 85–98, 2002
Laser ablation reveals regulation of ciliary activity by serotonergic neurons in molluscan embryos
Authors: Kuang Shihuan , Goldberg Jeffrey I.
Published: September 2002

Early in embryonic development, the pond snail Helisoma trivolvis exhibits a rotational behavior that is generated by beating of cilia in the dorsolateral and pedal bands. Although previous anatomical and pharmacological studies provided indirect evidence that a pair of serotonergic neurons, Embryonic Neurons C1 (ENC1s), is involved in regulating embryonic rotation, direct evidence linking ENC1 to ciliary function is still lacking. In the present study, we used laser microbeams to perturb ENC1 in vivo while monitoring ciliary activity in identified ciliary bands. A laser treatment protocol to specifically ablate ENC1 without damaging the surrounding cells was established. Unilateral laser treatment of ENC1 caused transient increases in the activity of the pedal and ipsidorsolateral cilia, lasting 30–50 min. In contrast, activity of cilia that were not anatomically associated with ENC1 was unaffected by laser treatment. Mianserin, an effective serotonin antagonist in Helisoma ciliated cells, decreased the overall CBF of pedal and dorsolateral cilia by reducing the occurrence of spontaneous CBF surges in these cilia. Finally, the cilioexcitatory action of ENC1 laser treatment was mimicked by serotonin and reduced in the presence of mianserin. These results suggest that laser treatment provokes a release of serotonin from ENC1, resulting in a prolonged elevation of activity in the target ciliary cells. We conclude that, in addition to their previously established role in regulating neurodevelopment, ENC1s also function as serotonergic motor neurons to regulate ciliary activity, and therefore the rotational behavior of early embryos. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 1–15, 2001
Drosophila neuropeptide F mediates integration of chemosensory stimulation and conditioning of the nervous system by food
Authors: Shen Ping , Cai Haini N.
Published: September 2002

The conserved neuropeptide Y (NPY) signaling pathway has been strongly implicated in the stimulation of food uptake in vertebrates as well as in the regulation of food conditioned foraging behaviors of Caenorhabditis elegans. Using in situ RNA hybridization and immunocytochemistry, we report the neuronal network of Drosophila neuropeptide F (dNPF), a human NPY homologue, in the larval central nervous system and its food‐dependent modifications. We provide indications that gustatory stimulation by sugar, but not its ingestion or metabolism, is sufficient to trigger long‐term, dose‐dependent alterations of the dNPF neuronal circuit through both dnpf activation and increased synaptic transmission. Our results strongly suggest that the dNPF neuronal circuit is an integral part of the sensory system that mediates food signaling, providing the neural basis for understanding how invertebrate NPY regulates food response. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 16–25, 2001
Calmodulin and profilin coregulate axon outgrowth in Drosophila
Authors: Kim You‐Seung , Furman Senta , Sink Helen , VanBerkum Mark F.A.
Published: September 2002

Coordinated regulation of actin cytoskeletal dynamics is critical to growth cone movement. The intracellular molecules calmodulin and profilin actively regulate actin‐based motility and participate in the signaling pathways used to steer growth cones. Here we show that in the developing Drosophila embryo, calmodulin and profilin convey complimentary information that is necessary for appropriate growth cone advance. Reducing calmodulin activity by expression of a dominant inhibitor (KA) stalls axon extension of pioneer neurons within the CNS, while a partial loss of profilin function decreases extension of motor axons in the periphery. Yet, surprisingly, when calmodulin and profilin are simultaneously reduced, the ability of both CNS pioneer axons and motor axons to extend beyond the choice points is restored. In the CNS, at the time when growth cones must decide whether to cross or not to cross the midline, a reduction in calmodulin and/or roundabout signaling causes axons to cross the midline inappropriately. These inappropriate crossings are suppressed when profilin activity is simultaneously reduced. Interestingly, the mutual suppression of calmodulin and profilin activity requires a minimal level of profilin. In KA combinations with profilin null alleles, defects in axon extension and midline guidance are synergistically enhanced rather than suppressed. Together, our data indicate that the growth cone must coordinate the activity of both calmodulin and profilin in order to advance past selected choice points, including those dictating midline crossovers. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 26–38, 2001
Primal and polar approach for computing the symmetric diagonally dominant projection
Authors: Raydan Marcos , Tarazaga Pablo
Published: September 2002

We solve the problem of minimizing the distance from a given matrix to the cone of symmetric and diagonally dominant matrices with positive diagonal (SDD+). Using the extreme rays of the polar cone we project onto the supporting hyperplanes of the faces of SDD+ and then, applying the cyclic Dykstra's algorithm, we solve the problem. Similarly, using the extreme rays of SDD+ we characterize the projection onto the polar cone, which also allows us to obtain the projection onto SDD+ by means of the orthogonal decomposition theorem for convex cones. In both cases the symmetry and the sparsity pattern of the given matrix are preserved. Preliminary numerical experiments indicate that the polar approach is a promising one. Copyright © 2002 John Wiley & Sons, Ltd.
Modular solvers for image restoration problems using the discrepancy principle
Authors: Blomgren Peter , Chan Tony F.
Published: September 2002

Many problems in image restoration can be formulated as either an unconstrained non‐linear minimization problem, usually with aTikhonov‐like regularization, where the regularization parameter has to be determined; or as a fully constrained problem, where an estimate of the noise level, either the variance or the signal‐to‐noise ratio, is available.

The formulations are mathematically equivalent. However, in practice, it is much easier to develop algorithms for the unconstrained problem, and not always obvious how to adapt such methods to solve the corresponding constrained problem.

In this paper, we present a new method which can make use ofanyexisting convergent method for the unconstrained problem to solve the constrained one. The new method is based on a Newton iteration applied to an extended system of non‐linear equations, which couples the constraint and the regularized problem, but it does not require knowledge of the Jacobian of the irregularity functional. The existing solver is only used as a black box solver, which for a fixed regularization parameter returns an improved solution to the unconstrained minimization problem given an initial guess.

The new modular solver enables us to easily solve the constrained image restoration problem; the solver automatically identifies the regularization parameter, during the iterative solution process.

We present some numerical results. The results indicate that even in the worst case the constrained solver requires only about twice as much work as the unconstrained one, and in some instances the constrained solver can be even faster. Copyright © 2002 John Wiley & Sons, Ltd.