bluuebunny/crossref_metadata_2025 huggingface dataset:
Near‐infrared Raman spectroscopy for the classification of epithelial pre‐cancers and cancers
Authors: Stone Nicholas , Kendall Catherine , Shepherd Neil , Crow Paul , Barr Hugh
Published: September 2002

The use of near‐infrared Raman spectroscopy to interrogate epithelial tissue biochemistry and hence distinguish between normal and abnormal tissues was investigated. Six different epithelial tissues from the larynx, tonsil, oesophagus, stomach, bladder and prostate were measured. Spectral diagnostic models were constructed using multivariate statistical analysis of the spectra to classify samples of epithelial cancers and pre‐cancers. Tissues were selected for clinical significance and to include those which develop into carcinoma from squamous, transitional or columnar epithelial cells. Rigorous histopathological protocols were followed and mixed pathology tissue samples were discarded from the study. Principal component fed linear discriminant models demonstrated excellent group separation, when tested by cross‐validation. Larynx samples, with squamous epithelial tissue, were separated into three distinct groups with sensitivities ranging from 86 to 90% and specificities from 87 to 95%. Bladder specimens, containing transitional epithelial tissue, were separated into five distinct groups with sensitivities of between 78 and 98% and specificities between 96 and 99%. Oesophagus tissue can contain both squamous and columnar cell carcinomas. A three group model discriminated the columnar cell pathological groups with sensitivities of 84–97% and specificities of 93–99%, and an eight group model combining both columnar and squamous tissues in the oesophagus was able to discriminate pathologies with sensitivities of 73–100% and specificities of 92–100%. It is likely that any overlap between pathology group predictions will have been due to a combination of the difficulty in histologically distinguishing between pre‐cancerous states and the fact that there is no biochemical boundary from one pathological group to the next, i.e. there is believed to be a continuum of progression from the normal to the diseased state. Copyright © 2002 John Wiley & Sons, Ltd.
Cancer gene detection using surface‐enhanced Raman scattering (SERS)
Authors: Vo‐Dinh Tuan , Allain Leonardo R. , Stokes David L.
Published: September 2002

We describe the development of a surface‐enhanced Raman scattering (SERS) method for cancer gene detection. The technology uses DNA gene probes based on SERS labels for gene detection. The detection method uses nanostructured metallic substrates as SERS‐active platforms. The surface‐enhanced Raman gene (SERGen) probes can be used to detect DNA targets via hybridization to DNA sequences complementary to these probes. The probes do not require the use of radioactive labels and have great potential to provide both sensitivity and selectivity. The usefulness of the SERGen approach and its applications in cancer gene diagnostics (e.g. BRCA1 breast cancer gene and BAX gene) is discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Trends in early mineralization of murine calvarial osteoblastic cultures: a Raman microscopic study
Authors: Stewart S. , Shea D. A. , Tarnowski C. P. , Morris M. D. , Wang D. , Franceschi R. , Lin D.‐L. , Keller E.
Published: September 2002

The elucidation of early mineralization of bone is of great interest to the medical world. A clearer understanding of the initial bone formation processes can lead to information regarding the treatment and prevention of bone disorders and fractures and the manufacture of prosthetics. We exploited the mineralizing capabilities of bone cell cultures (osteoblast cultures) to monitor the earliest composition changes during mineral formation using Raman spectroscopy. We observed the first mineralization in 8‐day‐old osteoblasts and identified the mineral species as one that is very similar to that found in fetal bone tissue, a lightly carbonated apatite. Raman spectra show that carbonation, an indicator of bone maturity, appears at the first detectable stage of mineralization in osteoblasts, and increases over time. We also isolated single osteoblasts by growing them on fused‐silica microscope slides. Not only did these cells exhibit abnormal growth patterns, but they also expressed a mineral composition different to a carbonated apatite. Raman spectra of this mineral species have spectral characteristics comparable to those of β‐tricalcium phosphate. Copyright © 2002 John Wiley & Sons, Ltd.
Electrophoresis to determine the molecular weight distribution in soluble proteins from various foods and their rumen‐resistant residues in cattle
Authors: Chaudhry Abdul Shakoor , Webster Anthony John F
Published: September 2002

Electrophoresis was used to visually identify and determine the molecular weight (MW) distribution of rumen‐degradable and rumen‐resistant or escape peptides in soluble proteins from 12 agricultural and distillers' food raw materials (RM) and their residues (RU) following 18 h of in sacco rumen incubation (dg18) in cattle. Soluble proteins were extracted by using water, salt, acid and alkali in succession to represent albumins, globulins, glutalin 1 and glutalin 2 respectively. RM and RU differed substantially in the MW range, number and intensity of bands for various soluble proteins. The bands were mostly below the MW range of 66 kDa. Low‐MW (<25 kDa) peptides were greater in number than high‐MW (>25 kDa) peptides in almost all soluble proteins from RM. Individual peptides behaved differently during rumen incubation. Their resistance to or escape from rumen degradation varied with the class of food, type of soluble protein and their MW range. On average, low‐MW albumins in agricultural foods were more resistant to rumen degradation (0.41 RM vs 0.12 RU; 29%) than their high‐MW counterparts (0.12 RM vs 0.02 RU; 21%). In contrast, high‐MW glutalin 1 was more resistant (0.03 RM vs 0.22 RU) than low‐MW glutalin 1 (0.09 RM vs 0.26 RU) in most agricultural foods. Globulins contained the least and glutalins the most resistant peptides in distillers' foods. While this study reveals an association between dg18 and protein type, structure and size, we do not recommend the immediate use of electrophoresis for routine food evaluation unless more studies are undertaken. It may, however, be suitable for further characterisation of the degradation of specific, selected peptides by specific micro‐organisms.

© 2001 Society of Chemical Industry
Effects of roasting on chemical composition and quality of different chestnut (Castanea sativa Mill) varieties
Authors: Künsch Ulrich , Schärer Hans , Patrian Bruno , Höhn Ernst , Conedera Marco , Sassella Alberto , Jermini Mauro , Jelmini Giorgio
Published: September 2002

In view of the ongoing revival of the chestnut orchards in southern Switzerland, evaluation of chestnut quality represents an important issue. Chestnuts are mainly consumed roasted. Three native varieties and a French one were roasted and submitted to sensory and chemical analysis in comparison to a commercial marrone variety imported from Italy. Weight loss due to roasting ranged from 23 to 30%. Roasted chestnuts contained 260–350 g kg−1 starch, 50–102 g kg−1 sucrose, 0.5–4.4 g kg−1 fructose, trace amounts of glucose and 9–15 g kg−1 total fatty acids. The main fatty acid in chestnuts was linoleic acid, amounting to 49% of total fatty acids. Sensory analysis showed that acceptance of chestnuts was highly dependent on sweetness, which was related to sucrose content. It should be at least 90 g kg−1. Varietal differences were observed in this study and it was shown that roasting caused little change in composition. Thus chestnut varieties used for roasting have to be selected accordingly. The commercial variety Marrone di Cuneo confirmed its superiority with regard to suitability for roasting. Among the Swiss varieties, only Lüina exhibited satisfactory quality.

© 2001 Society of Chemical Industry.
Classification of Slovak varietal white wines by volatile compounds
Authors: Pet'ka Ján , Mocák Ján , Farkaš Pavel , Balla Branko , Kováč Milan
Published: September 2002

Selected volatile compounds in the most widely produced Slovak varietal white wines, Welschriesling, Grüner Veltliner and Müller Thurgau, were analysed over a 3 year period. The study aimed to find a combination of volatiles that could serve as an input for the classification of these wines using multivariate data analysis. Significant differences among the wine samples as regards variety, producer and vintage were initially examined using ANOVA. Two classification techniques were also employed, namely linear (LDA) and quadratic (QDA) discriminant analyses. LDA revealed five volatile compounds that enabled a satisfactory classification of the wines by variety, and 10 volatiles for the classification of producers. QDA was slightly less successful in distinguishing the varieties; however, the classification of producers was comparable with the LDA results when using a significantly smaller number of variables.

© 2001 Society of Chemical Industry
The impact of confidence in expectations on consumer satisfaction
Authors: Spreng Richard A. , Page Thomas J.
Published: September 2002

Research into the construct relationships that form consumer satisfaction has advanced to a stage in which moderator variables need to be examined. The present research proposes and tests confidence in expectations as a potential moderator of these relationships. A laboratory study tests these hypotheses and finds support for them. Specifically, high‐confidence subjects use both disconfirmation and perceived performance to form feelings of satisfaction, whereas low‐confidence subjects use only perceived performance. Implications for both research and managerial practice are discussed. © 2001 John Wiley & Sons, Inc.
Experimental research and surgery: Why, how, and when?
Authors: Di Cataldo Antonio , Trombatore Giovanni , Ciraldo Rosanna , Rodolico Margherita , Sorbello Massimiliano , Li Destri Giovanni
Published: September 2002

Experimental research faces two great problems: the significant reduction of public funding and the firm opposition of the public opinion. The law forbids the use of large animals, so that it is possible to use small animals only, which require microsurgical techniques. However, even a skillful surgeon does not know how to perform microsurgery and has to begin a long and tiring training to master techniques. We think that experimental surgery should play a role because it tests the validity and safety of new surgical techniques and allows special pathophysiological aspects to be studied. Furthermore experimental surgery could represent an essential stage in the training of young surgeons. We should find a balance between observance of the law and respect of the animals and, on the other hand, the role of experimental surgery because we should not forget that its most important aim is the improvement of the health of the humankind.
A new vascularized adrenal transplantation model in the rat
Authors: Liu Dingyi , Qi Shijie , Xu Dasheng , Zhu Shengyun , Chen Huifang
Published: September 2002

A new microsurgical model of adrenal transplantation in the rat is described. An adrenal graft with its vascular supply, adrenal artery and vein, and the attachment of a segment of aorta and inferior vena cava (IVC) was transplanted to a recipient rat with end‐to‐side anastomoses between the donor IVC segment and the recipient IVC and between the donor aortic segment and the recipient aorta using 10‐0 nylon sutures. Using this model, different groups of recipient rats received iso‐ or allograft with or without immunosuppressive treatment were tested. This model provides a reliable and useful tool for research on endocrinology. © 2001 Wiley‐Liss, Inc. MICROSURGERY 21:124–126 2001
Effects of simultaneous kidney‐pancreaticoduodenal transplantation on diabetes‐induced renal insufficiency in rats
Authors: Yoon Jin Han , Jung Se Il , Cho Charles , Gil Myung Cheol , Kim Choon Gon
Published: September 2002

An investigation of the functional and histological changes was done after en‐bloc kidney‐pancreaticoduodenal transplantation (kpdt) in the diabetes‐induced, renal insufficient Lewis rats. For donor preparation, an end‐to‐side portocaval shunt was performed, and the aortic, vena caval segments, and ureter‐bladder patch were obtained. They were anastomosed microsurgically to recipient's aorta, vena cava, and bladder in end‐to‐side fashion. Of 15 diabetes‐induced kpdt rats, 14 survived. Two of the 14 surviving rats showed ischemic necrosis. The remaining 12 transplants showed well‐preserved glomeruli and Langerhans islets for 5 months postoperatively. Biochemical data comparing diabetic and sham‐operated rats (six rats each), six diabetic controls, and 12 kpdt rats showed no significant statistical difference at said observation period. The diabetes‐induced kpdt rats showed improvement of following biochemical data: within 1 week postoperatively, the glucose level fell from 300 to 115 mg/dL; BUN level from >20 to <20 mg/dL; the creatinine level from 1.5 to <1.2 mg/dL. The insulin level returned to normal, 1.1 ng/mL, in 2 weeks. The results demonstrate that the kpdt model is an effective and successful operative technique in diabetic rats and may provide effective therapeutic methods for diabetes‐induced renal insufficiency. © 2001 Wiley‐Liss, Inc. MICROSURGERY 21:173–178 2001
Nerve regeneration through an epineurial sheath: Its functional aspect compared with nerve and vein grafts
Authors: Karacaoğlu Ercan , Yüksel Fuat , Peker Fatih , Güler M. Mümtaz
Published: September 2002

Although nerve graft is still the only reliable choice in repair of defects in peripheral nerve structure, it has the disadvantage of donor nerve morbidity and of sometimes being unavailable. It has long been researched in alternate nerve grafts with other materials. Studies have shown that nerves could regenerate across short nerve gaps through various conduits, such as veins, pseudosheaths, and bioabsorbable tubes. Despite encouraging studies, their functional results remain unclear. The present study used 40 rats, in which nerve grafts, vein grafts, and epineurial tubes were placed into 1‐cm gaps in sciatic nerves created by resection. In one group, sciatic nerves were denuded of the surrounding epineurium, to assess the possible morbidity caused by epineurial sheath technique. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed using walking track analysis. The number of myelinated fibers and fiber diameters was measured and electron microscopic evaluation performed. Functionally, the index values were very close to each other in nerve graft and epineurial sheath groups. Morphometric analysis showed significance between the groups. The result of denuded sciatic nerve group was the same as the base track values. It was concluded that the ready availability of epineurial sheath as a conduit to span short nerve gaps could eliminate the morbidity associated with nerve graft harvest and capitalize on the potential benefits of neurotrophism in directing nerve regeneration. © 2001 Wiley‐Liss, Inc. Microsurgery 21:196–201 2001
Free tissue transfer in pregnancy: Guidelines for perioperative management
Authors: Meger G. Robert , Majewski W. Tomasz , Lyle W. Glenn
Published: September 2002

A successful free tissue transfer of serratus anterior muscle, to provide coverage for an open ankle defect in a pregnant patient, is described. Microvascular surgery in the presence of a viable pregnancy demands considerations unique to this situation. Although rarely possible, an attempt should be made to plan surgery to coincide with the second trimester, to lessen the risk of anesthesia to the fetus. Maternal positioning, fluid balance, and aspiration precautions need to be critically addressed. Close perioperative monitoring by an obstetrician is essential. The condition of pregnancy results in a hypercoagulable state that may lead to an increased risk of anastomotic failure. The use of anticoagulants results in increased risk of bleeding, not only for the patient but also for the fetus, as well as risk of teratogenic effects. Closely monitored heparin is considered safe in pregnancy as is low‐molecular‐weight dextran and low‐dose aspirin. Additional considerations include the use of narcotics and sedatives for comfort postoperatively, as well as antibiotic choices, if indicated. © 2001 Wiley‐Liss, Inc. Microsurgery 21:202–207 2001
Rat parathyroid allotransplantation: Influence of MHC antigen expression on graft survival
Authors: Timm S. , Otto C. , Hamelmann W. , Gassel A.M. , Timmermann W. , Ulrichs K. , Thiede A.
Published: September 2002

MHC antigen expression in parathyroid tissue and its influence on graft survival after allogeneic transplantation were investigated using a heterotopic rat transplantation model. MHC class I and II expression in parathyroid tissue of Lewis (LEW), Dark Agouti (DA), and Wistar‐Furth (WF) rats was analysed semi‐quantitatively by using immunohistochemistry. MHC class I expression was strong in DA, moderate in WF, and weak in LEW rats parenchyma, whereas MHC class II expression was negative. In the interstitium of all investigated tissue specimens, the proportion of MHC class II–expressing cells was low. Additionally, four groups were transplanted: 1) LEW to LEW, 2) DA to DA, 3) LEW to DA, and 4) WF to LEW. After syngeneic transplantation, graft survival could be documented over the whole observation period. A median graft survival of 20 (±2) days was observed after transplantation from LEW to DA, whereas grafts in the group WF to LEW were rejected after 13 (±1) days. The number of intra‐graft leucocytes expressing MHC class II molecules was the same in all groups, whereas increased levels of MHC class I in parathyroid tissue before transplantation resulted in a more rapid rejection. These results indicate that immunogenicity of rat parathyroid tissue might be determined by the amount of MHC class I expressed in donor parenchymal cells. Further experiments are necessary to validate this observation. © 2001 Wiley‐Liss, Inc. Microsurgery 21:221–222 2001
Use of colour duplex Doppler imaging in the postoperative assessment of buried free flaps
Authors: Stone Christopher A. , Dubbins P.A. , Morris Robert J.
Published: September 2002

The postoperative assessment of free flaps is essential to identify and act on signs of incipient flap failure. Where the flap is completely buried, this becomes almost impossible unless part of the flap is exteriorised or an overlying skin window is used. Alternatively, complicated and often impractical monitoring devices have been advocated, but these have failed to gain widespread acceptance. A simpler solution to this problem has been evaluated in a series of patients using colour duplex Doppler imaging. This re‐appraisal of a previously reported technique has been facilitated by updated technology in diagnostic radiology. Duplex Doppler imaging was confirmed as an accurate, non‐invasive, and inexpensive tool for the postoperative measurement of blood flow within the pedicles of five buried free flaps in four patients undergoing surgery in our unit. © 2001 Wiley‐Liss, Inc. Microsurgery 21:223–227 2001
Effect of isovolemic hemodilution with 3% albumin on thrombus formation at venous microanastomosis in rats
Authors: Farina Jayme A. , Piccinato Carlos E. , Rossi Marcos A. , Mazzer Nilton , Llorach‐Velludo Maria A.
Published: September 2002

The present investigation was undertaken to evaluate the effect of isovolemic hemodilution with 3% albumin per se on the prevention of microvascular venous thrombosis, using an experimental model in rats mimicking the thrombotic mechanisms similar to those in clinical situations. Male Wistar rats were allocated into two groups of 15 rats each: group 1, the nonhemodiluted group, consisted of animals submitted to microsurgical procedure to induce thrombosis without previous hemodilution; group 2, the hemodiluted group, consisted of animals submitted to microsurgical procedure to induce thrombosis with previous hemodilution. The histopathological examination clearly showed that the nonhemodiluted group presented well‐defined venous thrombosis in the anastomoses in 9 animals, totally occlusive in 8, and mural in 1. In contrast, in the hemodiluted group none of the anastomoses presented venous thrombosis, except for the presence of nonadherent blood clots. The clinical analysis of the anastomoses' patency, as evaluated by the empty‐full test, showed a significant reduction in rate of venous occlusion in the previously hemodiluted animals as compared with the nonhemodiluted animals 20 min after microsurgical anastomosis. Forty‐eight hours after anastomosis, the rate of venous occlusion was 66.7% in the nonhemodiluted group and 33.3% in the hemodiluted group; even though no significant difference could be detected during this time, the patency of anastomoses tended to be greater in the hemodiluted group than that of controls. The rate of spontaneous recanalization after 48 h was identical in both groups (16.6%) in comparison with the rates observed 20 min after the surgical procedure. In summary, moderate isovolemic hemodilution with 3% albumin was effective in reducing the rate of venous microanastomosis occlusion in rats 20 min after the surgical procedure, tending to maintain the anastomoses' patency after 48 h. In addition, 48 h after the microsurgical procedure, the rate of venous thrombosis as evaluated microscopically was significantly lower in the hemodiluted animals as compared with nonhemodiluted control animals. This points out that hemodilution with albumin could be a safe and adequate procedure to prevent thrombus formation at venous microanastomosis. © 2002 Wiley‐Liss, Inc. MICROSURGERY 22:152–157 2002
Evolution free boundary problem for equations of viscous compressible heat‐conducting capillary fluids
Authors: Zadrzyńska Ewa
Published: September 2002

In the paper the global motion of a viscous compressible heat conducting capillary fluid in a domain bounded by a free surface is considered. Assuming that the initial data are sufficiently close to a constant state and the external force vanishes we prove the existence of a global‐in‐time solution which is close to the constant state for any moment of time. The solution is obtained in such Sobolev–Slobodetskii spaces that the velocity, the temperature and the density of the fluid have $W_2^{2+\alpha,1+\alpha/2}$\nopagenumbers\end, $W_2^{2+\alpha,1+\alpha/2}$\nopagenumbers\end and $W_2^{1+\alpha,1/2+\alpha/2}$\nopagenumbers\end
—regularity with α∈(¾, 1), respectively. Copyright © 2001 John Wiley & Sons, Ltd.
Numerical analysis of the relationship between the coupling ratio and the time delay along microstrip lines using the FDTD method
Authors: Kim Yongjin , Lee Sangseol
Published: September 2002

The relationship between the coupling ratio and the time delay is analyzed using the FDTD method. The FDTD method for analyzing a microstrip structure with two lines is represented. An RVS (resistive voltage source) with single‐point excitation and a PML with eight layers are chosen for the FDTD method. For the various parameters of a microstrip structure, the relationships between the coupling ratio and time delay are numerically analyzed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 256–260, 2001.
Temperature characteristic analysis of a ferrite phase shifter in a grooved waveguide
Authors: Che Wenquan , Wang Chao‐Fu , Ma Jinping
Published: September 2002

A rigorous analysis of the temperature characteristics of a ferrite phase shifter in a grooved waveguide is carried out by using a combination of analytical and numerical methods. The numerical results are found to be in agreement with our measurements. The results obtained provide valuable guidance for the simulation of the property of the device in the high‐power case and for the optimization of the design of the device. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 156–159, 2001.
TEM horn optimized for transient radiation
Authors: Morrow Ivor L.
Published: September 2002

Theory and measurements are presented to show that careful shaping of antenna metalization can be used to design TEM horn antennas for ultra‐wideband applications involving high‐fidelity impulsive electromagnetic fields. The effect on the radiated pulse, spectral bandwidth, and transfer function is discussed. A numerical time‐domain formulation is described to compute the impulsive radiated far‐field waveform, and some experimental results are included to indicate the usefulness of the technique. The ringing action of the antenna is recognized as the crucial parameter constraining the usefulness of the design. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 161–164, 2001.
Effect of dielectric properties on moisture leveling in microwave‐assisted drying of laminar materials
Authors: Monzó‐Cabrera J. , Díaz‐Morcillo A. , Catalá‐Civera J. M. , De los Reyes E.
Published: September 2002

The microwave‐assisted drying of laminar materials has been studied, and a model is proposed to explain the behavior of these materials under microwave radiation. Different selective heating and drying tests of leather samples have been carried out, and drying curves showed a fast convergence as a proof of this effect. The obtained results look promising for applying this technique on an industrial scale. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 165–168, 2001.
Circularly polarized low‐profile square dielectric resonator antenna with a loading patch
Authors: Hsiao Fu‐Ren , Chiou Tzung‐Wern , Wong Kin‐Lu
Published: September 2002

With the loading of a rectangular patch having a suitable aspect ratio, circular polarization (CP) radiation of low‐profile square dielectric resonator (DR) antennas can easily be obtained. The proposed antenna design can easily be excited by using a microstrip‐line feed, and many prototypes with various sizes of the loading rectangular patch have been implemented. Details of the antenna design are described, and experimental results of the obtained CP performance are presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 157–159, 2001.
Experimental investigation of the frequency‐selective property of an array of dual‐tuned printed dipoles
Authors: Sarkar P. P. , Sarkar D. , Das S. , Sarkar S. , Chowdhury S. K.
Published: September 2002

The frequency‐selective property of an array of rectangular dipole microstrip patches resonant at dual frequencies (within the same frequency band) has been investigated experimentally. Measured data indicate a 40 dB separation between the transmission and reflection bands of the frequency‐selective surface (FSS) in the normalized transmitted electric field versus frequency plot. Experimental investigation of the FSS of an array of rectangular dipole microstrip patches resonant at a single frequency shows that the bandwidth of the reflection band is very narrow. In our present investigation, resonance at dual frequencies within the same frequency band has been used to broaden the bandwidth of the reflection band. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 189–190, 2001.
Optimization synthesis of broadband circularly polarized microstrip antennas by hybrid genetic algorithm
Authors: Zentner Radovan , Sipus Zvonimir , Bartolic Juraj
Published: September 2002

In this paper, the synthesis of a stacked patch antenna for circular polarization is presented. The antenna is analyzed by the full‐wave approach based on the method of moments in the spectral domain. In order to find the optimal antenna parameters, a hybrid genetic algorithm that combines a global search of the common genetic algorithm and the efficiency of the direct search method is developed. The experimental results show SWR<2, with an axial ratio lower than 4 dB within 14% bandwidth. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 197–201, 2001.
Design of narrowband amplifiers with conditionally stable transistors
Authors: Benvenuti Dario , Cicolani Maurizio , Pisa Stefano , Tommasino Pasquale , Trifiletti Alessandro
Published: September 2002

A technique to design narrowband amplifiers by using conditionally stable transistors is presented. The proposed analytical approach allows us to design lossless matching networks, by providing power matching at one port and minimum mismatch at the other port. The use of this technique leads to high gain as well as proper stability margins. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 208–210, 2001.
Small and high‐directivity bow‐tie patch antenna based on the Sierpinski fractal
Authors: Anguera Jaume , Puente Carles , Borja Carmen , Montero Raquel , Soler Jordi
Published: September 2002

The unique geometrical properties of fractals have been proven to be useful to design advanced antennas. Enhanced performance in terms of size, gain, or multifrequency behavior is observed in fractal‐shaped antennas. Here, a small and high‐directivity antenna based on the Sierpinski fractal is presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 239–241, 2001.
Allogeneic bone marrow transplantation in first remission rescues children with Philadelphia chromosome‐positive acute lymphoblastic leukemia: Tokyo Children's Cancer Study Group (TCCSG) studies L89‐12 and L92‐13*
Authors: Mori Taijiro , Manabe Atsushi , Tsuchida Masahiro , Hanada Ryoji , Yabe Hiromasa , Ohara Akira , Saito Tomohiro , Nakazawa Shinpei
Published: September 2002

Background

The prognosis of Philadelphia chromosome‐positive acute lymphoblastic leukemia (Ph+ ALL) is generally poor and reports from large studies are scarce. We evaluated the efficacy of allogeneic bone marrow transplantation (allo‐BMT) for children with this type of leukemia.

Procedure

The chemotherapy regimens consisted of an induction phase and very intensive consolidation followed by a reinduction phase and late intensification treatment. The selection of treatment modalities such as chemotherapy, allo‐BMT, or autologous transplantation was made by each institute. The principal endpoint was the outcome of children with Ph+ ALL according to the treatment options.

Results

Thirty‐two patients (4.3%) were diagnosed as Ph+ ALL out of the 741 cases of ALL consecutively enrolled in two protocols of the Tokyo Children's Cancer Study Group (TCCSG) from 1989 to 1994. Thirty patients (93.8%) were induced into complete remission (CR). Of these 30 patients, eight children electively received allo‐BMT in the first CR. Six of these patients are in continuous remission at a median follow‐up of 58 (range 48–105) months after the diagnosis. One patient died following recurrence and another patient died of graft vs. host disease. Three patients treated with autologous BMT or peripheral blood stem cell transplantation in the first CR experienced a subsequent relapse. In the remaining 19 patients, 13 patients were treated with very high‐risk chemotherapy alone and all relapsed within 28 months. One patient was excluded from the analysis because he was treated with standard‐risk chemotherapy until relapse. The other five patients were also excluded from the analysis because Philadelphia chromosome was not detected until they relapsed. None of the relapsed patients survived in spite of treatment including allo‐BMT. In multivariate analysis, only allo‐BMT remained as an independent factor for good prognosis.

Conclusions

The only way to cure children with Ph+ ALL was allo‐BMT in this study and its outcome seemed promising. Med Pediatr Oncol 2001;37:426–431. © 2001 Wiley‐Liss, Inc.
Extravascular proton‐density changes as a non‐BOLD component of contrast in fMRI of the human spinal cord
Authors: Stroman P.W. , Krause V. , Malisza K.L. , Frankenstein U.N. , Tomanek B.
Published: September 2002

The fractional signal intensity change (ΔS/S) observed during activation in T2‐weighted fMRI of the spinal cord has previously been shown to depend linearly on the echo time (TE) but to have a positive value of roughly 2.5% extrapolated to zero TE. In this study we investigated the origin of this finding by measuring the ΔS/S in spinal fMRI with very short TEs. Our results demonstrate that the ΔS/S does not approach zero, but has a value as high as 3.3% at TE = 11 ms. At TEs > 33 ms we observed the linear relationship between ΔS/S and TE as in previous studies. These data demonstrate that there is a non‐BOLD contribution to signal changes observed in spinal fMRI. We hypothesize that this contribution is a local proton density increase due to increased water exudation from capillaries with increased blood flow during neuronal activation, and term this effect “signal enhancement by extravascular protons” (SEEP). Magn Reson Med 48:122–127, 2002. © 2002 Wiley‐Liss, Inc.
Diffusion tensor imaging using single‐shot SENSE‐EPI
Authors: Bammer Roland , Auer Martin , Keeling Stephen L. , Augustin Michael , Stables Lara A. , Prokesch Rupert W. , Stollberger Rudolf , Moseley Michael E. , Fazekas Franz
Published: September 2002

SENSitivity Encoding (SENSE) greatly enhances the quality of diffusion‐weighted echo‐planar imaging (EPI) by reducing blurring and off‐resonance artifacts. Such improvement would also be desirable for diffusion tensor imaging (DTI), but measures derived from the diffusion tensor can be extremely sensitive to any kind of image distortion. Whether DTI is feasible in combination with SENSE has not yet been explored, and is the focus of this study. Using a SENSE‐reduction factor of 2, DTI scans in eight healthy volunteers were carried out with regular‐ and high‐resolution acquisition matrices. To further improve the stability of the SENSE reconstruction, a new coil‐sensitivity estimation technique based on variational calculus and the principles of matrix regularization was applied. With SENSE, maps of the trace of the diffusion tensor and of fractional anisotropy (FA) had improved spatial resolution and less geometric distortion. Overall, the geometric distortions were substantially removed and a significant resolution enhancement was achieved with almost the same scan time as regular EPI. DTI was even possible without the use of quadrature body coil (QBC) reference scans. Geometry‐factor‐related noise enhancement was only discernible in maps generated with higher‐resolution matrices. Error boundaries for residual fluctuations in SENSE reconstructions are discussed. Our results suggest that SENSE can be combined with DTI and may present an important adjunct for future neuroimaging applications of this technique. Magn Reson Med 48:128–136, 2002. © 2002 Wiley‐Liss, Inc.
Test‐retest reliability estimation of functional MRI data
Authors: Maitra Ranjan , Roys Steven R. , Gullapalli Rao P.
Published: September 2002

Functional magnetic resonance imaging (fMRI) data are commonly used to construct activation maps for the human brain. It is important to quantify the reliability of such maps. We have developed statistical models to provide precise estimates for reliability from several runs of the same paradigm over time. Specifically, our method extends the premise of maximum likelihood (ML) developed by Genovese et al. (Magn Reson Med 1997;38:497–507) by incorporating spatial context into the estimation process. Experiments indicate that our methodology provides more conservative estimates of true positives compared to those obtained by Genovese et al. The reliability estimates can be used to obtain voxel‐specific reliability measures for activated as well as inactivated regions in future experiments. We derive statistical methodology to determine optimal thresholds for region‐ and context‐specific activations. Empirical guidelines are also provided on the number of repeat scans to acquire in order to arrive at accurate reliability estimates. We report the results from experiments involving a motor paradigm performed on a single subject several times over a period of 2 months. Magn Reson Med 48:62–70, 2002. © 2002 Wiley‐Liss, Inc.
Application of the static dephasing regime theory to superparamagnetic iron‐oxide loaded cells
Authors: Bowen Chris V. , Zhang Xiaowei , Saab George , Gareau Paula J. , Rutt Brian K.
Published: September 2002

The relaxation rates of iron‐oxide nanoparticles compartmentalized within cells were studied and found to satisfy predictions of the static dephasing (SD) regime theory. THP‐1 cells in cell culture were loaded using two different iron‐oxide nanoparticles (superparamagnetic iron‐oxide (SPIO) and ultrasmall SPIO (USPIO)) with four different iron concentrations (0.05, 0.1, 0.2, and 0.3 mg/ml) and for five different incubation times (6, 12, 24, 36, and 48 hr). Cellular iron‐oxide uptake was assessed using a newly developed imaging version of MR susceptometry, and was found to be linear with both dose and incubation time. R sensitivity to iron‐oxide loaded cells was found to be 70 times greater than for R2, and 3100 times greater than for R1. This differs greatly from uniformly distributed nanoparticles and is consistent with a cellular bulk magnetic susceptibility (BMS) relaxation mechanism. The cellular magnetic moment was large enough that R2′ relaxivity agreed closely with SD regime theory predictions for all cell samples tested

where the local magnetic dose (LMD) is the sample magnetization due to the presence of iron‐oxide particles). Uniform suspensions of SPIO and USPIO produced R2′ relaxivities that were a factor of 3 and 8 less, respectively, than SD regime theory predictions. These results are consistent with theoretical estimates of the required mass of iron per compartment needed to guarantee SD‐regime‐dominant relaxivity. For cellular samples, R2 was shown to be dependent on both the concentration and distribution of iron‐oxide particles, while R2′ was sensitive to iron‐oxide concentration alone. This work is an important first step in quantifying cellular iron content and ultimately mapping the density of a targeted cell population. Magn Reson Med 48:52–61, 2002. © 2002 Wiley‐Liss, Inc.
High‐resolution MRI of cardiac function with projection reconstruction and steady‐state free precession
Authors: Peters Dana C. , Ennis Daniel B. , McVeigh Elliot R.
Published: September 2002

The purpose of this study was to investigate the trabecular structure of the endocardial wall of the living human heart, and the effect of that structure on the measurement of myocardial function using MRI. High‐resolution MR images (0.8 × 0.8 × 8 mm voxels) of cardiac function were obtained in five volunteers using a combination of undersampled projection reconstruction (PR) and steady‐state free precession (SSFP) contrast in ECG‐gated breath‐held scans. These images provide movies of cardiac function with new levels of endocardial detail. The trabecular‐papillary muscle complex, consisting of a mixture of blood and endocardial structures, is measured to constitute as much as 50% of the myocardial wall in some sectors. Myocardial wall strain measurements derived from tagged MR images show correlation between regions of trabeculae and papillary muscles and regions of high strain, leading to an overestimation of function in the lateral wall. Magn Reson Med 48:82–88, 2002. Published 2002 Wiley‐Liss, Inc.
Image distortion correction in EPI: Comparison of field mapping with point spread function mapping
Authors: Zeng Huairen , Constable R. Todd
Published: September 2002

Echo‐planar imaging (EPI) can provide rapid imaging by acquiring a complete k‐space data set in a single acquisition. However, this approach suffers from distortion effects in geometry and intensity, resulting in poor image quality. The distortions, caused primarily by field inhomogeneities, lead to intensity loss and voxel shifts, the latter of which are particularly severe in the phase‐encode direction. Two promising approaches to correct the distortion in EPI are field mapping and point spread function (PSF) mapping. The field mapping method measures the field distortions and translates these into voxel shifts, which can be used to assign image intensities to the correct voxel locations. The PSF approach uses acquisitions with additional phase‐encoding gradients applied in the x, y, and/or z directions to map the 1D, 2D, or 3D PSF of each voxel. These PSFs encode the spatial information about the distortion and the overall distribution of intensities from a single voxel. The measured image is the convolution of the undistorted density and the PSF. Measuring the PSF allows the distortion in geometry and intensity to be corrected. This work compares the efficacy of these methods with equal time allowed for field mapping and PSF mapping. Magn Reson Med 48:137–146, 2002. © 2002 Wiley‐Liss, Inc.
Mapping myocardial perfusion with an intravascular MR contrast agent: Robustness of deconvolution methods at various blood flows
Authors: Neyran Bruno , Janier Marc F. , Casali Cendrine , Revel Didier , Canet Soulas Emmanuelle P.
Published: September 2002

Evaluation of quantitative parameters such as regional myocardial blood flow (rMBF), blood volume (rMBV), and mean transit time (rMTT) by MRI is gaining acceptance for clinical applications, but still lacks robust postprocessing methods for map generation. Moreover, robustness should be preserved over the full range of myocardial flows and volumes. Using experimental data from an isolated pig heart preparation, synthetic MR kinetics were generated and four deconvolution approaches were evaluated. These methods were then applied to the first‐pass T1 images of the isolated pig heart using an intravascular contrast agent and rMBF, rMBV and rMTT maps were generated. In both synthetic and experimental data, the fit between calculated and original data reached equally good results with the four techniques. rMBV was the only parameter estimated correctly in numerical experiments. Moreover, using the algebraic method ARMA, abnormal regions were well delineated on rMBV maps. At high flows, rMBF was underestimated at the experimental noise level. Finally, rMTT maps appeared noisy and highly unreliable, especially at high flows. In conclusion, over the myocardial flow range, i.e., 0–400 ml/min/100g, rMBF identification was biased in presence of noise, whereas rMBV was correctly identified. Thus, rMBV mapping could be a fast and robust way to detect abnormal myocardial regions. Magn Reson Med 48:166–179, 2002. © 2002 Wiley‐Liss, Inc.
Independent component analysis of fMRI data in the complex domain
Authors: Calhoun V.D. , Adalı T. , Pearlson G.D. , van Zijl P.C.M. , Pekar J.J.
Published: September 2002

In BOLD fMRI a series of MR images is acquired and examined for task‐related amplitude changes. These functional changes are small, so it is important to maximize detection efficiency. Virtually all fMRI processing strategies utilize magnitude information and ignore the phase, resulting in an unnecessary loss of efficiency. As the optimum way to model the phase information is not clear, a flexible modeling technique is useful. To analyze complex data sets, independent component analysis (ICA), a data‐driven approach, is proposed. In ICA, the data are modeled as spatially independent components multiplied by their respective time‐courses. There are thus three possible approaches: 1) the time‐courses can be complex‐valued, 2) the images can be complex‐valued, or 3) both the time‐courses and the images can be complex‐valued. These analytic approaches are applied to data from a visual stimulation paradigm, and results from three complex analysis models are presented and compared with magnitude‐only results. Using the criterion of the number of contiguous activated voxels at a given threshold, an average of 12–23% more voxels are detected by complex‐valued ICA estimation at a threshold of |Z| > 2.5. Additionally, preliminary results from the complex models reveal a phase modulation similar to the magnitude time‐course in some voxels, and oppositely modulated in other voxels. Magn Reson Med 48:180–192, 2002. © 2002 Wiley‐Liss, Inc.
The formation of dunes, antidunes, and rapidly damping waves in alluvial channels
Authors: Huang L.‐H. , Chiang Y.‐L.
Published: September 2002

Under the effect of a constant current for a long time, a water channel of infinitely long and constant depth interacting with a uniform sandbed of infinite thickness is used to simulate the formation of dunes, antidunes and rapidly damping waves in alluvial channels. The theory of potential flow is applied to the channel flow, while Biot's theory of poroelasticity is adopted to deal with erodible bed material. The governing equations, together with free surface, bed surface, and far field boundary conditions, form a complete boundary‐value problem without applying empirical sediment discharge formulas as in conventional researches. The comparison of the present result with Kennedy's (Journal of Fluid Mechanics, 1963; 16: 521–544) instability analysis not only indicates the appropriateness of the present work, but also reveals the advantage of the present study due to its ability to find all kinds of bed forms (including the rapidly damping waves that Kennedy could not find) and of solving for the unclear lagged distance δ introduced in Kennedy's work. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization and reconstruction of a rock fracture surface by geostatistics
Authors: Marache A. , Riss J. , Gentier S. , Chilès J.‐P.
Published: September 2002

It is well understood that, in studying the mechanical and hydromechanical behaviour of rock joints, their morphology must be taken into account. A geostatistical approach has been developed for characterizing the morphology of fracture surfaces at a decimetre scale. This allows the analysis of the spatial variability of elevations, and their first and second derivatives, with the intention of producing a model that gives a numerical three‐dimensional (3D) representation of the lower and upper surfaces of the fracture. Two samples (I and II) located close together were cored across a natural fracture. The experimental data are the elevations recorded along profiles (using recording steps of 0.5 and 0.02 mm, respectively, for the samples I and II). The goal of this study is to model the surface topography of sample I, so getting estimates for elevations at each node of a square grid whose mesh size will be, for mechanical purposes, no larger than the recording step. Since the fracture surface within the sample core is not strictly horizontal, geostatistical methods are applied to residuals of elevations of sample I. Further, since structural information is necessary at very low scale, theoretical models of variograms of elevations, first and second derivatives are fitted using data of both that sample I and sample II. The geostatistical reconstructions are computed using kriging and conditional simulation methods. In order to validate these reconstructions, variograms and distributions of experimental data are compared with variograms and distributions of the fitted data. Copyright © 2002 John Wiley & Sons, Ltd.
A quick check of network performance
Authors: Hicks Jeffrey T. , Walker John Q.
Published: September 2002

Have you ever tried to measure the response time across a network? Do you sometimes wonder what throughput rate you're getting over a particular link? Are you concerned about the impact of adding streaming multimedia traffic to a network? Would you like to know the exact route your data is taking? Individual tools are available to measure the throughput and response time of your applications, trace a network route, or test a network's capacity for handling multimedia traffic. But a software tool called Qcheck can perform all of these tasks and more, while providing a quick check of network performance. Copyright © 2001 John Wiley & Sons, Ltd.