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Polarization-controlled spectral transformation of unamplified femtosecond pulses in multiple waveguide channels of a photonic-crystal fiber

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LASER PHYSICS 2004年第5期14卷 760-763页

作者： Konorov, SO Fedotov, AB Mitrokhin, VP Sidorov-Biryukov, DA Kondrat'ev, YN Shevandin, VS Dukel'skii, KV Khokhlov, AV Zheltikov, AM Moscow MV Lomonosov State Univ Fac Phys Moscow 119899 Russia Moscow MV Lomonosov State Univ Ctr Int Laser Moscow 119899 Russia SI Vavilov State Opt Inst St Petersburg 199034 Russia

We experimentally demonstrate polarization control of spectral transformation of femtosecond laser pulses in an array of micron and submicron fused silica threadlike waveguide channels in a photonic-crystal fiber. The spectrum and the amplitude of the anti-Stokes signal generated in such waveguide channels are controlled by rotating the polarization of linearly polarized unamplified pulses of 800-nm Ti: sapphire-laser radiation used as a pump. Polarization frequency switching of the anti-Stokes signal is also demonstrated.

关键词： MICROSTRUCTURE-FIBER OPTICAL-FIBERS LASER-PULSES SUPERCONTINUUM GENERATION SPECTROSCOPY guidance MODES LIGHT AIR

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Transmission of ultrashort pulses through hollow photonic-crystal fibers with passbands in the visible and infrared spectral ranges

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LASER PHYSICS 2004年第5期14卷 780-784页

作者： Konorov, SO Fedotov, AB Beloglazov, VI Skibina, NB Scalora, M Vaselli, M Zheltikov, AM Moscow MV Lomonosov State Univ Fac Phys Moscow 119992 Russia Moscow MV Lomonosov State Univ Ctr Int Laser Moscow 119992 Russia Inst Technol & Proc Glass Struct Saratov 410044 Russia USA Aviat & Missile Command Ctr Res Dev & Engn Weap Sci Directorate Redstone Arsenal AL 35898 USA CNR Area Ric Ist Proc Chim Fisici I-56124 Pisa Italy

Hollow-core photonic-crystal fibers with passbands in the range of wavelengths from 0.4 to 2.0 mum are demonstrated. Changes in the envelope and the evolution of the spectral phase and the chirp of femtosecond pulses propagating through hollow photonic-crystal fibers are experimentally studied. Envelope and phase distortions of ultrashort pulses transmitted through such fibers are shown to be controlled by the detuning of the carrier frequency of laser pulses from the central frequency of the passband in the transmission of the fiber. Near the passband edges, which map the edges of photonic band gaps of the fiber cladding, ultrashort pulses transmitted through the fiber display considerable envelope distortions, as well as frequency- and time-dependent phase shifts.

关键词： COMPRESSION PROPAGATION guidance LIGHT AIR

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New techniques in image-guided percutaneous biopsy

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CARDIOVASCULAR AND INTERVENTIONAL RADIOLOGY 2004年第2期27卷 91-104页

作者： Gupta, S Univ Texas MD Anderson Canc Ctr Dept Diagnost Radiol Houston TX 77030 USA

Image-guided percutaneous biopsy is a well-established and safe technique for obtaining tissue specimens from various regions of the body and plays a crucial role in patient management. Improvements in needle designs, development of new biopsy techniques, and continual advances in image-guidance technology have improved the safety and efficacy of the procedure. Lesions previously considered relatively inaccessible can now be safely biopsied. This review looks at the recent technologic developments in image guidance for percutaneous biopsy procedures. Improvements in needle design and other innovations intended to enhance the diagnostic yield of biopsy specimens are briefly discussed. Also described are some new techniques and unconventional approaches that help provide safe access to difficult-to-reach lesions.

关键词： biopsies biopsy technology imaging guidance

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Cost comparison analysis of low-field (0.23 T) MRI- and CT-guided bone biopsies

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EUROPEAN RADIOLOGY 2004年第1期14卷 123-128页

作者： Alanen, J Keski-Nisula, L Blanco-Sequeiros, R Tervonen, O Oulu Univ Hosp Dept Radiol PL 50 Oulu 90029 Finland Tampere Univ Hosp Dept Radiol PL 2000 Tampere 33521 Finland

The aim of this study was to analyze and compare the costs of low-field (0.23 T) MRI- and CT-guided bone biopsies. The cost comparison consisted of 18 MRI-guided and 12 CT-guided bone biopsies performed during a 1-year period. The costs and activities of these two methods were analyzed by using activity-based cost accounting (ABC). The costs of MRI-guided bone biopsy (1205 Euro) were 2.55-fold compared with those of the CT-guided bone biopsy (472 Euro). The higher costs of the biopsy procedure in MRI were due to the higher material (5.57-fold) and personnel (2.73-fold) costs. The MRI-guided bone biopsies proved to be considerably more expensive than CT-guided bone biopsies. This was due to the higher material costs, especially the highly priced MRI compatible instrumentation and the longer procedure time. The MRI guidance in performing bone biopsies should be justified on the basis of the better accuracy and the lack of radiation. Evaluations of cost-effectiveness concerning MRI-guided bone biopsy are needed.

关键词： costs and cost analysis bone needle biopsy guidance magnetic resonance computed tomography

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Primordial germ cell migration in the chick and mouse embryo: the role of the chemokine SDF-1/CXCL12

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DEVELOPMENTAL BIOLOGY 2004年第2期272卷 351-361页

作者： Stebler, J Spieler, D Slanchev, K Molyneaux, KA Richter, U Cojocaru, V Tarabykin, V Wylie, C Kessel, M Raz, E Max Planck Inst Biophys Chem Dept Mol Cell Biol D-37077 Gottingen Germany Childrens Hosp Res Fdn Div Dev Biol Cincinnati OH 45229 USA Max Planck Inst Biophys Chem Dept Biol Mol D-37077 Gottingen Germany Max Planck Inst Expt Med D-37075 Gottingen Germany

As in many other animals, the primordial germ cells (PGCs) in avian and reptile embryos are specified in positions distinct from the positions where they differentiate into sperm and egg. Unlike in other organism however, in these embryos, the PGCs use the vascular system as a vehicle to transport them to the region of the gonad where they exit the blood vessels and reach their target. To determine the molecular mechanisms governing PGC migration in these species, we have investigated the role of the chemokine stromal cell-derived factor-1 (SDF-1 /CXCL12) in guiding the cells towards their target in the chick embryo. We show that sdf-1 mRNA is expressed in locations where PGCs are found and towards which they migrate at the time they leave the blood vessels. Ectopically expressed chicken SDF-1alpha led to accumulation of PGCs at those positions. This analysis, as well as analysis of gene expression and PGC behavior in the mouse embryo, suggest that in both organisms, SDF-1 functions during the second phase of PGC migration, and not at earlier phases. These findings suggest that SDF-1 is required for the PGCs to execute the final migration steps as they transmigrate through the blood vessel endothelium of the chick or the gut epithelium of the mouse. (C) 2004 Elsevier Inc. All rights reserved.

关键词： PGC chicken cell migration chemotaxis guidance chemokine SDF-1 CXCL12 CXCR4 dead end

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MR imaging-guided axillary node biopsy for breast cancer: initial findings

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EUROPEAN RADIOLOGY 2004年第1期14卷 151-156页

作者： Yamagami, T Yuen, S Sawai, K Nishimura, T Kyoto Prefectural Univ Med Dept Radiol Kamigyo Ku Kyoto 6028566 Japan Kyoto Prefectural Univ Med Dept Endocrine & Breast Surg Kamigyo Ku Kyoto 6028566 Japan

The aim of this study was to evaluate the usefulness and feasibility of preoperative sentinel node needle biopsy of the breast under guidance of open MR imaging, a method that we developed. Nine patients with breast cancer in whom the axillary lymph nodes were not palpable underwent preoperative sentinel node needle biopsy under real-time MR imaging guidance. The sentinel nodes were identified before the biopsy using CT and MR imaging. Diagnostic ability of this method was compared with that of the operative diagnosis. Sentinel nodes were correctly identified in all 9 patients. The MR imaging-guided sentinel node needle biopsy was performed for all of the 9 patients, and, in 7 (77.8%) of the 9, a specimen sufficient for pathologic evaluation was obtained;and in 6, whether malignancy existed was precisely diagnosed. No serious complications were noted. This experience indicates the possibility of a precise diagnosis of whether the sentinel node in breast cancer is benign or malignant without surgery.

关键词： breast neoplasm biopsy diagnosis staging lymphatic system magnetic resonance guidance

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Percutaneous US-guided RF thermal ablation for malignant renal tumors: preliminary results in 13 patients

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EUROPEAN RADIOLOGY 2004年第12期14卷 2303-2310页

作者： Veltri, A De Fazio, G Malfitana, V Isolato, G Fontana, D Tizzani, A Gandini, G Univ Turin Inst Diagnost & Intervent Radiol I-10126 Turin Italy Univ Turin Inst Urol I-10126 Turin Italy

Minimally invasive treatment for small renal cell carcinoma (RCC) can be necessary in selected patients and, anyway, is desirable. In situ ablation techniques, including RFA, have been developed. The aim of this study is to evaluate the feasibility, safety and short-term local effectiveness of percutaneous US-guided RFA in a small series, as well as mid-term patient outcome. Thirteen patients with a total of 18 tumors ( 17 small lesions, 35 mm in size or less, and a larger one, 75 mm in size) underwent 19 RFA sessions. Seven patients had a solitary kidney, and three suffered from VHL disease, too. We treated four lesions in a patient with a bilateral tumor. In another patient, three lesions were ablated. Seventeen tumors were RCC;one was a metastasis from lung cancer. Eight lesions were parenchymal, six exophytic, two parenchymal/ exophytic, one parenchymal/ central and one central. A monopolar RF system with multitined expandable electrode needles was used. The 35-mm lesion underwent two sessions;the 75-mm lesion was treated with transcatheter arterial embolization before RFA. Tumors with complete loss of contrast enhancement at short-term CT ( or MR) were considered successfully treated. Percutaneous US-guided RFA was always feasible without major complications. The success rate after a single treatment in tumors less than 35 mm in size was 88.2% (15/17) and rose to 94.1% (16/17) after the second treatment of the largest lesion. After a mean 14-month follow-up, no successfully treated lesions recurred locally. Only the patient with metastasis from lung cancer died from disease progression in a further location, while all other patients are alive, with renal function still sufficient to avoid dialysis. US guidance allows an easy and safe percutaneous approach for RFA of small non-parahilar RCC. The treatment is locally effective and can be proposed as a minimally invasive therapy for patients with contraindications to surgery or to those expressing an informed cons

关键词： kidney neoplasms therapy kidney interventional procedures radiofrequency ablation ultrasound guidance

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Sema3A regulates the timing of target contact by cranial sensory axons

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JOURNAL OF COMPARATIVE NEUROLOGY 2004年第1期470卷 13-24页

作者： Dillon, TE Saldanha, J Giger, R Verhaagen, J Rochlin, MW Loyola Univ Dept Biol Chicago IL 60626 USA Univ Rochester Ctr Aging & Dev Biol Rochester NY 14642 USA Netherlands Inst Brain Res Grad Sch Neurosci NL-1105 AZ Amsterdam Netherlands

The trigeminal ganglion provides the somatosensory innervation for the anterior rat tongue. At early embryonic stages (embryonic day [E] 12-13) pre-tongue explants repel trigeminal axon outgrowth, and this is mediated by Sema3A (Rochlin and Farbman [1998] J. Neurosci. 18:6840-6852;Rochlin et al. [2000] J. Comp. Neurol. 422:579-593). Despite a decrease in repulsion by E14 and older tongue explants, Sema3A mRNA persists throughout the dorsal epithelium through E18, after axons have begun to penetrate papilla epithelium. We investigated the hypothesis that Sema3A continues to act as a repellent and that subpopulations of trigeminal axons that penetrate the epithelium become unresponsive to Sema3A. Sema3A repelled trigeminal axons in vitro regardless of the neurotrophic factor used to stimulate axon outgrowth, but the minimum level of Sema3A required to repel depended on the neurotrophic factor. Thus, in vitro, trigeminal axons are repelled by Sema3A when they would be penetrating the Sema3A-mRNA rich epithelium in vivo. Whereas dorsal epithelium on tongue explants dissected at stages preceding target contact (E15) repelled trigeminal axons in vitro, explants dissected at later stages (E18), after axons would have penetrated the epithelium in vivo, were not repellent. To determine whether Sema3A prevents premature target penetration in vivo, we assessed the timing of target contact by sensory axons in Sema3A(-/minus;) and (+/+) mice. Contact of the epithelium occurs prematurely in Sema3A(-/minus;) mice, but not penetration. Taken together, our data imply that Sema3A acts as a short-range repellent that regulates the timing of target contact by trigeminal axons. (C) 2004 Wiley-Liss, Inc.

关键词： tongue development chemorepellent guidance trigeminal

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Spatiotemporal properties of cytoplasmic cyclic AMP gradients can alter the turning behaviour of neuronal growth cones

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EUROPEAN JOURNAL OF NEUROSCIENCE 2004年第4期19卷 791-797页

作者： Munck, S Bedner, P Bottaro, T Harz, H Univ Munich Bioimaging Zentrum D-82152 Martinsried Germany Univ Bonn Inst Genet D-5300 Bonn Germany Ecole Super Phys & Chim Ind Ville Paris Paris France

Growth cones, the terminal structures of elongating neurites, use extracellular guidance information in order to navigate to appropriate target cells. The directional information of guidance cues is transduced to a cytoplasmic gradient of messenger molecules across the growth cone leading to rearrangements of the cytoskeleton. One messenger molecule regulating growth cone turning is cAMP, which is also known to be sufficient to direct growth cone attraction. Cytoplasmic cAMP gradients have been generated in the present study by photolysing caged cAMP with UV light focused on one side of growth cones of chick sensory neurons. Using this method we show that only specific time patterns of pulsed cAMP release are capable of inducing growth cone turning whereas others, which release the same amount of cAMP, are ineffective. Theoretical calculations show that diverse time patterns produce different intracellular gradients, which were visualized directly in HeLa cells expressing cAMP-sensitive ion channels as a reporter system. Together these data indicate that the spatiotemporal properties of the intracellular gradient are crucial for growth cone turning.

关键词： caged cyclic AMP chick cyclic nucleotide gated channel guidance

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Patterns of continuing professional education in registered dietitians and dietetic technicians, registered

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JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 2004年第3期104卷 437-441页

作者： Williams, KA Keim, KS Johnson, CA Oklahoma State Univ Bur Social Res Stillwater OK 74078 USA

This study compared the continuing professional education (CPE) activities of registered dietitians (RDs) with those of dietetic technicians, registered (DTRs). A descriptive research study was used with data from the baseline survey evaluating the Commission on Dietetic Registration's (CDR) Professional Development Portfolio. The survey was sent to 3,530 randomly selected RDs and DTRs;1,429 surveys were returned (40.5% response rate), with 41% of RDs contacted responding and 32% of DTRs responding. guidance used when selecting CPE activities and type of CPE activity selected were measured. DTRs sought more guidance than RDs when selecting CPE activities (P=.001). A significantly higher percentage of RDs than DTRs selected lectures, workshops, journal clubs, satellite courses, exhibits, professional leadership, professional reading, and poster sessions as CPE activities (P<.05). These findings will aid CPE providers in knowing which CPE activities are typically selected by both dietetics credential groups. DTRs may need guidance in selecting CPE activities.

关键词： Certification Dietetics Education Medical Continuing Public Health Professional 证明膳食学教育医学继续 Diet Therapy baseline studies CPE gene Medical guidance certification

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