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Sample records for dynamic breast magnetic

  1. Mammography combined with breast dynamic contrast-enhanced-magnetic resonance imaging for the diagnosis of early breast cancer

    Institute of Scientific and Technical Information of China (English)

    Yakun He; Guohui Xu; Jin Ren; Bin Feng; Xiaolei Dong; Hao Lu; Changjiu He

    2016-01-01

    Objective The aim of this study was to investigate the application of mammography combined with breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for the diagnosis of early breast cancer. Methods Mammography and DCE-MRI were performed for 120 patients with breast cancer (malignant, 102; benign; 18). Results The sensitivity of mammography for early diagnosis of breast cancer was 66.67%, specificity was 77.78%, and accuracy was 68.33%. The sensitivity of MRI for early diagnosis of breast cancer was 94.12%, specificity was 88.89%, and accuracy was 93.33%. However, the sensitivity of mammography combined with DCE-MRI volume imaging with enhanced water signal (VIEWS) scanning for early diagnosis of breast cancer was 97.06%, specificity was 94.44%, and accuracy was 96.67%. Conclusion Mammography combined with DCE-MRI increased the sensitivity, specificity, and accuracy of diagnosing early breast cancer.

  2. Fibroadenoma of the axillary accessory breast: diagnostic value of dynamic magnetic resonance imaging.

    Science.gov (United States)

    Sawa, Munehisa; Kawai, Nobuyuki; Sato, Morio; Takeuchi, Taizo; Tamaki, Takeshi; Oura, Shoji

    2010-10-01

    Accessory breast is synonymous with polymastia or supernumerary breast tissue. An accessory breast without a nipple or areola is rare. We report a case of fibroadenoma of an accessory breast with no nipple or areola in a 41-year-old woman who presented with a right axillary mass associated with five small nodules in the normally situated breast. Magnetic resonance imaging (MRI) showed the accessory breast surrounding the tumor. We ignored the presence of the component surrounding the mass and made a preoperative diagnosis of an axillary mass of possible metastases from multiple breast cancers or breast cancer of unknown origin associated with multiple breast fibroadenomas. From a retrospective view, based on the histological results, MRI and dynamic MRI demonstrated a tiny component of breast-like tissue surrounding the axillary mass and an enhancement pattern typical of fibroadenoma for the axillary mass. For the later diagnosis of the axillary mass, the interpretation of whether the component of breast tissue surrounding the axillary mass was present is crucial. If the component exists, a tumor that originated from the accessory breast should be foremost in the differential diagnosis. Dynamic MRI appears to contribute to the diagnosis of fibroadenoma of an accessory breast before biopsy or surgical resection.

  3. Dynamic Breast Magnetic Resonance Imaging without Complications in a Patient with Dual-Chamber Demand Pacemaker

    Energy Technology Data Exchange (ETDEWEB)

    Sardanelli, F.; Lupo, P.; Esseridou, A.; Fausto, A.; Quarenghi, M. [Policlinico San Donato, San Donato Milanese, Milan (Italy). Depts. of Radiology, Arrhythmia and Electrophysiology Center

    2006-02-15

    Mammography and ultrasound indicated a cancer of the right breast in a 77-year-old woman with a dual-chamber demand pacemaker. The patient was not pacemaker-dependent. She underwent breast 1.5T magnetic resonance imaging (MRI) (dynamic gradient echo sequence with Gd-DOTA 0.1 mmol/kg). Before the patient entered the MR room, the configuration of the device was changed (the response to magnet was switched from asynchronous to off and the rate-responsive algorithm was disabled). No relevant modifications of heart rhythm or rate were observed during the MR examination. No symptom was reported. Immediately after the examination, the pacemaker interrogation showed neither program changes nor alert warnings. MRI detected a bifocal cancer in the right breast which allowed tailored breast-conserving treatment to be initiated. Histopathology confirmed a bifocal invasive ductal carcinoma.

  4. A Novel Approach to Contrast-Enhanced Breast Magnetic Resonance Imaging for Screening: High-Resolution Ultrafast Dynamic Imaging

    NARCIS (Netherlands)

    Mann, R.M.; Mus, R.D.M.; Zelst, J. van; Geppert, C.; Karssemeijer, N.; Platel, B.

    2014-01-01

    The use of breast magnetic resonance imaging (MRI) as screening tool has been stalled by high examination costs. Scan protocols have lengthened to optimize specificity. Modern view-sharing sequences now enable ultrafast dynamic whole-breast MRI, allowing much shorter and more cost-effective procedur

  5. Radiogenomic analysis of breast cancer: dynamic contrast enhanced - magnetic resonance imaging based features are associated with molecular subtypes

    Science.gov (United States)

    Wang, Shijian; Fan, Ming; Zhang, Juan; Zheng, Bin; Wang, Xiaojia; Li, Lihua

    2016-03-01

    Breast cancer is one of the most common malignant tumor with upgrading incidence in females. The key to decrease the mortality is early diagnosis and reasonable treatment. Molecular classification could provide better insights into patient-directed therapy and prognosis prediction of breast cancer. It is known that different molecular subtypes have different characteristics in magnetic resonance imaging (MRI) examination. Therefore, we assumed that imaging features can reflect molecular information in breast cancer. In this study, we investigated associations between dynamic contrasts enhanced MRI (DCE-MRI) features and molecular subtypes in breast cancer. Sixty patients with breast cancer were enrolled and the MR images were pre-processed for noise reduction, registration and segmentation. Sixty-five dimensional imaging features including statistical characteristics, morphology, texture and dynamic enhancement in breast lesion and background regions were semiautomatically extracted. The associations between imaging features and molecular subtypes were assessed by using statistical analyses, including univariate logistic regression and multivariate logistic regression. The results of multivariate regression showed that imaging features are significantly associated with molecular subtypes of Luminal A (p=0.00473), HER2-enriched (p=0.00277) and Basal like (p=0.0117), respectively. The results indicated that three molecular subtypes are correlated with DCE-MRI features in breast cancer. Specifically, patients with a higher level of compactness or lower level of skewness in breast lesion are more likely to be Luminal A subtype. Besides, the higher value of the dynamic enhancement at T1 time in normal side reflect higher possibility of HER2-enriched subtype in breast cancer.

  6. A novel approach to contrast-enhanced breast magnetic resonance imaging for screening: high-resolution ultrafast dynamic imaging.

    Science.gov (United States)

    Mann, Ritse M; Mus, Roel D; van Zelst, Jan; Geppert, Christian; Karssemeijer, Nico; Platel, Bram

    2014-09-01

    The use of breast magnetic resonance imaging (MRI) as screening tool has been stalled by high examination costs. Scan protocols have lengthened to optimize specificity. Modern view-sharing sequences now enable ultrafast dynamic whole-breast MRI, allowing much shorter and more cost-effective procedures. This study evaluates whether dynamic information from ultrafast breast MRI can be used to replace standard dynamic information to preserve accuracy. We interleaved 20 ultrafast time-resolved angiography with stochastic trajectory (TWIST) acquisitions (0.9 × 1 × 2.5 mm, temporal resolution, 4.3 seconds) during contrast inflow in a regular high-resolution dynamic MRI protocol. A total of 160 consecutive patients with 199 enhancing abnormalities (95 benign and 104 malignant) were included. The maximum slope of the relative enhancement versus time curve (MS) obtained from the TWIST and curve type obtained from the regular dynamic sequence as defined in the breast imaging reporting and data system (BIRADS) lexicon were recorded. Diagnostic performance was compared using receiver operating characteristic analysis. All lesions were visible on both the TWIST and standard series. Maximum slope allows discrimination between benign and malignant disease with high accuracy (area under the curve, 0.829). Types of MS were defined in analogy to BIRADS curve types: MS type 3 implies a high risk of malignancy (MS >13.3%/s; specificity, 85%), MS type 2 yields intermediate risk (MS 6.4%/s), and MS type 1 implies a low risk (MS BIRADS curve type analysis does (area under the curve, 0.812 vs 0.692; P = 0.0061). Ultrafast dynamic breast MRI allows detection of breast lesions and classification with high accuracy using MS. This allows substantial shortening of scan protocols and hence reduces imaging costs, which is beneficial especially for screening.

  7. Dynamic contrast-enhanced magnetic resonance imaging for prediction of response to neoadjuvant chemotherapy in breast cancer

    Science.gov (United States)

    Fu, Juzhong; Fan, Ming; Zheng, Bin; Shao, Guoliang; Zhang, Juan; Li, Lihua

    2016-03-01

    Breast cancer is the second leading cause of women death in the United States. Currently, Neoadjuvant Chemotherapy (NAC) has become standard treatment paradigms for breast cancer patients. Therefore, it is important to find a reliable non-invasive assessment and prediction method which can evaluate and predict the response of NAC on breast cancer. The Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) approach can reflect dynamic distribution of contrast agent in tumor vessels, providing important basis for clinical diagnosis. In this study, the efficacy of DCE-MRI on evaluation and prediction of response to NAC in breast cancer was investigated. To this end, fifty-seven cases of malignant breast cancers with MRI examination both before and after two cycle of NAC were analyzed. After pre-processing approach for segmenting breast lesions and background regions, 126-dimensional imaging features were extracted from DCE-MRI. Statistical analyses were then performed to evaluate the associations between the extracted DCE-MRI features and the response to NAC. Specifically, pairwise t test was used to calculate differences of imaging features between MRI examinations before-and-after NAC. Moreover, the associations of these image features with response to NAC were assessed using logistic regression. Significant association are found between response to NAC and the features of lesion morphology and background parenchymal enhancement, especially the feature of background enhancement in normal side of breast (P=0.011). Our study indicate that DCE-MRI features can provide candidate imaging markers to predict response of NAC in breast cancer.

  8. Dynamic MRI of the breast.

    Science.gov (United States)

    Ercolani, P; Valeri, G; Amici, F

    1998-05-01

    To describe the rationale, the technical requirements and the examination technique of dynamic magnetic resonance studies of the breast and to assess the role of this method in the clinical diagnostic protocol. We reviewed the relative literature and compared the results with our personal experience. The earliest reports on the possibility of differentiating carcinoma from benign tissue with magnetic resonance imaging came from Germany, where in 1986 Heywang and coworkers used T1-weighted spin-echo sequences before and after i.v. Gd-DTPA administration with an imaging time of approximately 5 mins and 5 mm slice thickness. With advances in magnetic resonance technology, Heywang Koebrunner adopted a static three-dimensional fast low-angle shot technique permitting advantages of three-dimensional imaging and permit dynamic studies (values over 95%. The time/signal intensity curves revealed the rapid and strong enhancement of malignancies, the gradual and strong enhancement of the only fibroadenoma studied, and the gradual and mild contrast uptake of benign dysplasia. In 1992, in nearly 1000 dynamic examinations, Kaiser and Reiser reported 98.3% sensitivity, 97.0% specificity, 82.1% predictive value and 97.2% accuracy. The combination of rapid acquisition with techniques that preserve high spatial resolution may improve specificity by allowing the study of lesion morphology as well as of enhancement patterns. A whole-breast imaging technique has been reported which permits acquisition times < 15 s by partial sampling of the central k-space region superimposed on high-resolution three-dimensional images. Dynamic magnetic resonance imaging of the breast is currently an important step of the clinical protocol of breast diseases, but there is no established study protocol yet.

  9. Effectiveness of dynamic contrast-enhanced magnetic resonance imaging in evaluating clinical responses to neoadjuvant chemotherapy in breast cancer

    Institute of Scientific and Technical Information of China (English)

    LIU Yin-hua; YE Jing-ming; XU Ling; HUANG Qing-yun; ZHAO Jian-xin; DUAN Xue-ning; QIN Nai-shan; WANG Xiao-ying

    2011-01-01

    Background Use of neoadjuvant chemotherapy necessitates assessment of response to cytotoxic drugs.The aim of this research was to investigate the effectiveness of dynamic contrast-enhanced magnetic resonance imaging (MRI) for evaluating clinical responses to neoadjuvant chemotherapy in breast cancer patients.Methods We examined patients receiving neoadjuvant chemotherapy for primary breast cancer between October 2007and September 2008.Dynamic contrast-enhanced MRI was used to examine breast tumors prior to and after neoadjuvant chemotherapy.The MRI examination assessed tumors using Response Evaluation Criteria in Solid Tumors (RECIST).The Miller-Payne grading system was used as a histopathological examination to assess the effect of the treatment.We examined the relationship between the results of RECIST and histopathological criteria.In addition,we used time-signal intensity curves (MRI T-SI) to further evaluate the effects of neoadjuvant chemotherapy on tumor response.Results MRI examination of patients completing four three-week anthracycline-taxanes chemotherapy treatment revealed that no patients had complete responses (CR),58 patients had partial responses (PR),29 patients had stable disease (SD),and four with progressive disease (PD).The effectiveness of neoadjuvant chemotherapy (CR + PR) was 63.7% (58/91).The postoperative histopathological evaluations revealed the following:seven G5 (pCR) cases (7.7%),39G4 cases (42.9%),16 G3 cases (17.6%),23 G2 cases (25.3%),and six G1 cases (6.6%).The effectiveness (G5 + G4 +G3) was 68.1% (62/91).MRI T-SI standards classified 53 responding cases,29 stable cases,and nine progressing cases.These results indicated that the treatment was 58.2% effective (53/91) overall.Conclusions Dynamic contrast-enhanced MRI and histopathological standards were highly correlated.Importantly,MRI T-SI evaluation was found to be useful in assessing the clinical effectiveness of neoadjuvant chemotherapy.

  10. Clinical application of bilateral high temporal and spatial resolution dynamic contrast-enhanced magnetic resonance imaging of the breast at 7 T

    Energy Technology Data Exchange (ETDEWEB)

    Pinker, K.; Baltzer, P.; Bernathova, M.; Weber, M.; Leithner, D.; Helbich, T.H. [Medical University Vienna, Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Waehringer Guertel 18-20, 1090, Vienna (Austria); Bogner, W.; Trattnig, S.; Gruber, S.; Zaric, O. [Medical University Vienna, Department of Biomedical Imaging and Image-guided Therapy, MR Centre of Excellence, Vienna (Austria); Abeyakoon, O. [King' s College, Department of Radiology, London (United Kingdom); Dubsky, P. [Medical University Vienna, Department of Surgery, Vienna (Austria); Bago-Horvath, Z. [Medical University Vienna, Department of Pathology, Vienna (Austria)

    2014-04-15

    The objective of our study was to evaluate the clinical application of bilateral high spatial and temporal resolution dynamic contrast-enhanced magnetic resonance imaging (HR DCE-MRI) of the breast at 7 T. Following institutional review board approval 23 patients with a breast lesion (BIRADS 0, 4-5) were included in our prospective study. All patients underwent bilateral HR DCE-MRI of the breast at 7 T (spatial resolution of 0.7 mm{sup 3} voxel size, temporal resolution of 14 s). Two experienced readers (r1, r2) and one less experienced reader (r3) independently assessed lesions according to BI-RADS registered. Image quality, lesion conspicuity and artefacts were graded from 1 to 5. Sensitivity, specificity and diagnostic accuracy were assessed using histopathology as the standard of reference. HR DCE-MRI at 7 T revealed 29 lesions in 23 patients (sensitivity 100 % (19/19); specificity of 90 % (9/10)) resulting in a diagnostic accuracy of 96.6 % (28/29) with an AUC of 0.95. Overall image quality was excellent in the majority of cases (27/29) and examinations were not hampered by artefacts. There was excellent inter-reader agreement for diagnosis and image quality parameters (κ = 0.89-1). Bilateral HR DCE-MRI of the breast at 7 T is feasible with excellent image quality in clinical practice and allows accurate breast cancer diagnosis. (orig.)

  11. Contrast kinetics of the malignant breast tumour - border versus centre enhancement on dynamic midfield MRI

    DEFF Research Database (Denmark)

    Marklund, M.; Torp-Pedersen, S.; Bentzon, N.;

    2008-01-01

    PURPOSE: To quantify the border versus centre enhancement of malignant breast tumours on dynamic magnetic resonance mammography. MATERIALS AND METHODS: Fifty-two women diagnosed with primary breast cancer underwent dynamic magnetic resonance mammography (Omniscan 0.2 mmol/kg bodyweight...... receptor negative tumours. CONCLUSION: The border/centre enhancement difference in malignant breast tumours is easily visualized on midfield dynamic magnetic resonance mammography. The dynamic behaviour is significantly correlated to histological features and receptor status of the tumours Udgivelsesdato...

  12. Three-dimensional contrast enhanced ultrasound score and dynamic contrast-enhanced magnetic resonance imaging score in evaluating breast tumor angiogenesis: Correlation with biological factors

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Wan-Ru, E-mail: jiawanru@126.com [Department of Diagnostic Ultrasound, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, No. 197 Rui Jin 2nd Road, Shanghai 200025 (China); Chai, Wei-Min, E-mail: chai_weimin@yahoo.com.cn [Department of Radiology, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, No. 197 Rui Jin 2nd Road, Shanghai 200025 (China); Tang, Lei, E-mail: jessietang1003@163.com [Department of Diagnostic Ultrasound, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, No. 197 Rui Jin 2nd Road, Shanghai 200025 (China); Wang, Yi, E-mail: xiatian.0602@163.com [Department of Diagnostic Ultrasound, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, No. 197 Rui Jin 2nd Road, Shanghai 200025 (China); Fei, Xiao-Chun, E-mail: xcf0222@163.com [Department of Pathology, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, No. 197 Rui Jin 2nd Road, Shanghai 200025 (China); Han, Bao-San, E-mail: hanbaosan@126.com [Department of Comprehensive Breast Health Center, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, No. 197 Rui Jin 2nd Road, Shanghai 200025 (China); Chen, Man, E-mail: lucyjia1370@126.com [Department of Diagnostic Ultrasound, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, No. 197 Rui Jin 2nd Road, Shanghai 200025 (China)

    2014-07-15

    Objective: To explore the clinical value of three-dimensional contrast enhanced ultrasound (3D-CEUS) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) score systems in evaluating breast tumor angiogenesis by comparing their diagnostic efficacy and correlation with biological factors. Methods: 3D-CEUS was performed in 183 patients with breast tumors by Esaote Mylab90 with SonoVue (Bracco, Italy), DCE-MRI was performed on a dedicated breast magnetic resonance imaging (DBMRI) system (Aurora Dedicated Breast MRI Systems, USA) with a dedicated breast coil. 3D-CEUS and DCE-MRI score systems were created based on tumor perfusion and vascular characteristics. Microvessel density (MVD), vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP-2, MMP-9) expression were measured by immunohistochemistry. Results: Pathological results showed 35 benign and 148 malignant breast tumors. MVD (P = 0.000, r = 0.76), VEGF (P = 0.000, r = 0.55), MMP-2 (P = 0.000, r = 0.39) and MMP-9 (P = 0.000, r = 0.41) expression were all significantly different between benignity and malignancy. Regarding 3D-CEUS 4 points as cutoff value, the sensitivity, specificity and accuracy were 85.1%, 94.3% and 86.9%, respectively, and correlated well with MVD (P = 0.000, r = 0.50), VEGF (P = 0.000, r = 0.50), MMP-2 (P = 0.000, r = 0.50) and MMP-9 (P = 0.000, r = 0.66). Taking DCE-MRI 5 points as cutoff value, the sensitivity, specificity and accuracy were 86.5%, 94.3% and 88.0%, respectively and also correlated well with MVD (P = 0.000, r = 0.52), VEGF (P = 0.000, r = 0.44), MMP-2 (P = 0.000, r = 0.42) and MMP-9 (P = 0.000, r = 0.35). Conclusions: 3D-CEUS score system displays inspiring diagnostic performance and good agreement with DCE-MRI scoring. Moreover, both score systems correlate well with MVD, VEGF, MMP-2 and MMP-9 expression, and thus have great potentials in tumor angiogenesis evaluation.

  13. Ultrafast magnetization dynamics

    OpenAIRE

    Woodford, S.

    2008-01-01

    This thesis addresses ultrafast magnetization dynamics from a theoretical perspective. The manipulation of magnetization using the inverse Faraday effect has been studied, as well as magnetic relaxation processes in quantum dots. The inverse Faraday effect – the generation of a magnetic field by nonresonant, circularly polarized light – offers the possibility to control and reverse magnetization on a timescale of a few hundred femtoseconds. This is important both for the technological advant...

  14. Ultrafast Magnetization Dynamics

    OpenAIRE

    Woodford, S.

    2008-01-01

    This thesis addresses ultrafast magnetization dynamics from a theoretical perspective. The manipulation of magnetization using the inverse Faraday effect has been studied, as well as magnetic relaxation processes in quantum dots. The inverse Faraday effect – the generation of a magnetic field by nonresonant, circularly polarized light – offers the possibility to control and reverse magnetization on a timescale of a few hundred femtoseconds. This is important both for the technological advant...

  15. Role of Dynamic Magnetic Resonance Imaging in Preoperative Evaluation of Breast Conserving Surgery for Breast Cancer%动态磁共振成像在乳腺癌保乳术中的术前评估作用

    Institute of Scientific and Technical Information of China (English)

    范培芝; 张超杰; 刘鹏; 张志功; 唐梅徕; 顾晓文; 郑维; 李艳春

    2012-01-01

    [Objective] To evaluate the role of dynamic contrast-enhanced magnetic resonance imaging (MRI) in prcopcrativc evaluation of breast-conserving surgery for breast cancer. [Methods! Totally 65 female breast cancer patients with the average age of 35. 8 years old took prcopcrativc mammography and MRI examination. Mammography and MRI examination were used to evaluate the feasibility of breast-conserving surgery. Pathological diagnosis was used to evaluate the accuracy of MRI in the assessment of breast cancer in cutting edge and with multi-center lesions. [Results! Among 65 patients with breast cancer, 64. 6% of the patients could undergo breast-conserving surgery by mammography prcopcrativc evaluation which was lower than that by MRI cvaluation(83. 1 %) , and there was significant difference between thcm( P Dynamic contrast-enhanced MRI in the prcopcrativc evaluation of young women with stage I~Iib breast cancer undergoing breast conserving surgery can more accurately determine multi-center lesion and incisal margin range than mammography, and is more helpful for deciding whether to adopt breast conserving surgery and more precisely determine surgical margin.%[目的]评价动态增强磁共振成像(MRI)在乳腺癌保乳根治术的术前评估作用.[方法]平均年龄35.8岁的65 例女性乳腺癌患者,术前均行钼靶及MRI检查,对钼靶、MRI评估是否可行保乳手术进行分析,通过病理诊断来评价MRI在评估乳腺癌多中心病灶以及切缘范围上的准确性.[结果]65例患者中,钼靶术前评估认为可保乳术患者64.6%,低于MRI评估的83.1%,且两者相比差异有显著性(P<0.05).对癌块切缘判断准确率MRI为80%,显著高于钼靶的53.8%(P<0.05).[结论]在中青年女性的I~IIb期乳腺癌保乳术的术前评估方法中,动态增强MRI成像较钼靶

  16. Typical atypical findings on dynamic MRI of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, Kathinka D., E-mail: kurk@sus.no [Department of Radiology, Stavanger University Hospital, Postbox 8100, 4068 Stavanger (Norway); Roy, Sumit, E-mail: rosu@sus.no [Department of Radiology, Stavanger University Hospital, Postbox 8100, 4068 Stavanger (Norway); Moedder, Ulrich, E-mail: Moedder@uni-duesseldorf.de [Institute of Diagnostic Radiology, Duesseldorf University Hospital (Germany); Skaane, Per, E-mail: Per.Skaane@ulleval.no [Department of Radiology, Ullevaal University Hospital, University of Oslo (Norway); Saleh, Andreas, E-mail: saleh@uni-duesseldorf.de [Institute of Diagnostic Radiology, Duesseldorf University Hospital (Germany)

    2010-11-15

    Dynamic contrast enhanced magnetic resonance imaging (DCE MRI) of the breast has become an important tool to detect and characterize breast disease. The American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) provides a standardized vocabulary for describing the morphologic features and contrast kinetics of breast lesions. However, some lesions may show morphologic and dynamic MR features not consistent with their histologic nature resulting in incorrect categorization as malignant or benign. Another cause of diagnostic problems is artifacts. Thus correct interpretation of dynamic MRI of the breast demands knowledge of the most common pitfalls encountered in clinical practice. A pictorial overview of these is presented, with particular reference to the differentiation of malignant tumors from benign lesions.

  17. Multicenter prospective study of magnetic resonance imaging prior to breast-conserving surgery for breast cancer

    Institute of Scientific and Technical Information of China (English)

    Liu Qian; Liu Yinhua; Xu Ling; Duan Xuening; Li Ting; Qin Naishan; Kang Hua

    2014-01-01

    Background This multicenter prospective study aimed to assess the utility of dynamic enhanced magnetic resonance imaging (MRI) prior to breast-conserving surgery for breast cancer.Methods The research subjects were drawn from patients with primary early resectable breast cancer treated in the breast disease centers of six three-level hospitals in Beijing from 1 January 2010 to 31 December 2012.The participants were allocated to a breast-conserving surgery group (breast-conserving group) or a total mastectomy group (total mastectomy group).Enhanced MRI was used to measure breast volume,longest diameter of tumor and tumor volume.The correlations between these measurements and those derived from histopathologic findings were assessed.The relationships between the success rate of breast-conserving surgery and MRI-and pathology-based measurement results were statistically analyzed in the breast-conserving group.Results The study included 461 cases in the total mastectomy group and 195 in the breast-conserving group.Allocation to these groups was based on clinical indications and patient preferences.The cut-off for concurrence between MRI-and pathology-based measurements of the longest diameter of tumor was set at 0.3 cm.In the total mastectomy group,the confidence interval for 95% concurrence of these measurements was 35.41%-44.63%.Correlation coefficients for MRI and histopathology-based measurements of breast volume,tumor volume and tumor volume/breast volume ratio were r=0.861,0.569,and 0.600,respectively (all P <0.001).In the breast-conserving group,with 0.30 cm taken as the cut-off for concurrence,the 95% confidence interval for MRI and pathology-based measurements of the longest diameter of tumor was 29.98%-44.01%.The subjective and objective success rates for breast-conserving surgery were 100% and 88.54%,respectively.Conclusions There were significant correlations between dynamic enhanced MRI-and histopathology-based measurements of the longest

  18. Functional imaging of the angiogenic switch in a transgenic mouse model of human breast cancer by dynamic contrast enhanced magnetic resonance imaging.

    Science.gov (United States)

    Consolino, Lorena; Longo, Dario Livio; Dastrù, Walter; Cutrin, Juan Carlos; Dettori, Daniela; Lanzardo, Stefania; Oliviero, Salvatore; Cavallo, Federica; Aime, Silvio

    2016-07-15

    Tumour progression depends on several sequential events that include the microenvironment remodelling processes and the switch to the angiogenic phenotype, leading to new blood vessels recruitment. Non-invasive imaging techniques allow the monitoring of functional alterations in tumour vascularity and cellularity. The aim of this work was to detect functional changes in vascularisation and cellularity through Dynamic Contrast Enhanced (DCE) and Diffusion Weighted (DW) Magnetic Resonance Imaging (MRI) modalities during breast cancer initiation and progression of a transgenic mouse model (BALB-neuT mice). Histological examination showed that BALB-neuT mammary glands undergo a slow neoplastic progression from simple hyperplasia to invasive carcinoma, still preserving normal parts of mammary glands. DCE-MRI results highlighted marked functional changes in terms of vessel permeability (K(trans) , volume transfer constant) and vascularisation (vp , vascular volume fraction) in BALB-neuT hyperplastic mammary glands if compared to BALB/c ones. When breast tissue progressed from simple to atypical hyperplasia, a strong increase in DCE-MRI biomarkers was observed in BALB-neuT in comparison to BALB/c mice (K(trans)  = 5.3 ± 0.7E-4 and 3.1 ± 0.5E-4; vp  = 7.4 ± 0.8E-2 and 4.7 ± 0.6E-2 for BALB-neuT and BALB/c, respectively) that remained constant during the successive steps of the neoplastic transformation. Consistent with DCE-MRI observations, microvessel counting revealed a significant increase in tumour vessels. Our study showed that DCE-MRI estimates can accurately detect the angiogenic switch at early step of breast cancer carcinogenesis. These results support the view that this imaging approach is an excellent tool to characterize microvasculature changes, despite only small portions of the mammary glands developed neoplastic lesions in a transgenic mouse model.

  19. Model of THz Magnetization Dynamics

    Science.gov (United States)

    Bocklage, Lars

    2016-01-01

    Magnetization dynamics can be coherently controlled by THz laser excitation, which can be applied in ultrafast magnetization control and switching. Here, transient magnetization dynamics are calculated for excitation with THz magnetic field pulses. We use the ansatz of Smit and Beljers, to formulate dynamic properties of the magnetization via partial derivatives of the samples free energy density, and extend it to solve the Landau-Lifshitz-equation to obtain the THz transients of the magnetization. The model is used to determine the magnetization response to ultrafast multi- and single-cycle THz pulses. Control of the magnetization trajectory by utilizing the THz pulse shape and polarization is demonstrated. PMID:26956997

  20. Breast conserving therapy and magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Tsuneaki; Masuda, Yu; Hachiya, Junichi; Nitatori, Toshiaki; Fukushima, Hisayoshi; Uchigasaki, Shinya [Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine

    1996-12-01

    Recently, breast conserving therapy has been widely accepted in our country. The extensive intraductal component (EIC) is a serious problem in breast conserving therapy, because it is well-known that EIC frequently causes locoregional recurrence in preserved breast parenchyma. Magnetic resonance imaging (MRI) is a useful method for detecting breast masses due to its excellent contrast resolution. We studied the application of MRI to detection of intraductal spread in twenty-two patients. All cases were revealed invasive cancer with intraductal spread by histopathological examination. MRI findings of intraductal spread can be divided into two major groups. One is daugter nodules or strand-like enhancement and the other is bridging enhancement. We also reffered to the preliminary study of MR-guiding transcutaneous aspiration biopsy of mammographically and clinically occult breast masses. (author)

  1. Breast magnetic resonance imaging guided biopsy

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Bo La; Kim, Sun Mi; Jang, Mi Jung [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Cho, Nariya; Moon, Woo Kyung [Dept. of Radiology, Seoul National University Hospital, Seoul (Korea, Republic of); Kim, Hak Hee [Dept. of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2016-06-15

    Despite the high sensitivity of breast magnetic resonance imaging (MRI), pathologic confirmation by biopsy is essential because of limited specificity. MRI-guided biopsy is required in patients with lesions only seen on MRI. We review preprocedural considerations and the technique of MRI-guided biopsy, challenging situations and trouble-shooting, and correlation of radiologic and pathologic findings.

  2. Nonlinear magnetization dynamics in nanosystems

    CERN Document Server

    Mayergoyz, Isaak D; Serpico, Claudio

    2014-01-01

    As data transfer rates increase within the magnetic recording industry, improvements in device performance and reliability crucially depend on the thorough understanding of nonlinear magnetization dynamics at a sub-nanoscale level. This book offers a modern, stimulating approach to the subject of nonlinear magnetization dynamics by discussing important aspects such as the Landau-Lifshitz-Gilbert (LLG) equation, analytical solutions, and the connection between the general topological and structural aspects of dynamics. An advanced reference for the study and understanding of non

  3. [A study on the predictive and evaluational value of molecular subtypes and dynamic contrast-enhanced magnetic resonance imaging of neoadjuvant chemotherapy for breast cancer].

    Science.gov (United States)

    Liu, Wen-qing; Ye, Jing-ming; Xu, Ling; Liu, Qian; Zhao, Jian-xin; Duan, Xue-ning; Liu, Yin-hua

    2013-08-01

    To investigate the predictive value of molecular subtypes and the evaluational value of dynamic contrast-enhanced MRI of neoadjuvant chemotherapy for breast cancer. From January 2010 to December 2011, the 79 patients diagnosed as primary invasive breast cancer, having received 6 cycles of neoadjuvant chemotherapy and finished the mastectomy or the breast conserving surgery entered this study. A total of 79 patients participated in this prospective study. There were 6 (7.6%) luminal A cases, 42 (53.2%) luminal B cases, 14 HER-2 (17.7%) positive cases and 17 (21.5%) triple negative cases. The associations between molecular subtypes and clinical response as well as the pathological response were analyzed. The predictive value of molecular subtypes for the neoadjuvant chemotherapy was studied. Clinical effective rate was 85.3% (66/79). There was no statistical correlation between molecular subtypes and clinical effective rate. Pathologic effective rate was 79.7% (63/79). There was no statistical correlation between molecular subtypes and pathologic effective rate. Twenty-seven case achieved pathologic complete remission (pCR) in all the patients. No case achieved pCR in the patients classified as Luminal A. Twelve cases (28.6%, 12/42) achieved pCR in the luminal B patients.Five cases (5/14) achieved pCR in the HER-2 overexpression patients. Ten cases (10/17) achieved pCR in the triple-negative patients. There was a statistical correlation between the molecular subtypes and the pCR rate (P = 0.039), and between clinical evaluation by dynamic contrast-enhanced MRI and evaluation of pathological response (r = 0.432, P = 0.000). Molecular subtypes and dynamic contrast-enhanced MRI have a good value of predicting and evaluating the response of neoadjuvant chemotherapy on breast cancer.

  4. Variations of dynamic contrast-enhanced magnetic resonance imaging in evaluation of breast cancer therapy response: a multicenter data analysis challenge.

    Science.gov (United States)

    Huang, Wei; Li, Xin; Chen, Yiyi; Li, Xia; Chang, Ming-Ching; Oborski, Matthew J; Malyarenko, Dariya I; Muzi, Mark; Jajamovich, Guido H; Fedorov, Andriy; Tudorica, Alina; Gupta, Sandeep N; Laymon, Charles M; Marro, Kenneth I; Dyvorne, Hadrien A; Miller, James V; Barbodiak, Daniel P; Chenevert, Thomas L; Yankeelov, Thomas E; Mountz, James M; Kinahan, Paul E; Kikinis, Ron; Taouli, Bachir; Fennessy, Fiona; Kalpathy-Cramer, Jayashree

    2014-02-01

    Pharmacokinetic analysis of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) time-course data allows estimation of quantitative parameters such as K (trans) (rate constant for plasma/interstitium contrast agent transfer), v e (extravascular extracellular volume fraction), and v p (plasma volume fraction). A plethora of factors in DCE-MRI data acquisition and analysis can affect accuracy and precision of these parameters and, consequently, the utility of quantitative DCE-MRI for assessing therapy response. In this multicenter data analysis challenge, DCE-MRI data acquired at one center from 10 patients with breast cancer before and after the first cycle of neoadjuvant chemotherapy were shared and processed with 12 software tools based on the Tofts model (TM), extended TM, and Shutter-Speed model. Inputs of tumor region of interest definition, pre-contrast T1, and arterial input function were controlled to focus on the variations in parameter value and response prediction capability caused by differences in models and associated algorithms. Considerable parameter variations were observed with the within-subject coefficient of variation (wCV) values for K (trans) and v p being as high as 0.59 and 0.82, respectively. Parameter agreement improved when only algorithms based on the same model were compared, e.g., the K (trans) intraclass correlation coefficient increased to as high as 0.84. Agreement in parameter percentage change was much better than that in absolute parameter value, e.g., the pairwise concordance correlation coefficient improved from 0.047 (for K (trans)) to 0.92 (for K (trans) percentage change) in comparing two TM algorithms. Nearly all algorithms provided good to excellent (univariate logistic regression c-statistic value ranging from 0.8 to 1.0) early prediction of therapy response using the metrics of mean tumor K (trans) and k ep (=K (trans)/v e, intravasation rate constant) after the first therapy cycle and the corresponding

  5. Ultrafast magnetization dynamics in diluted magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Morandi, O [INRIA Nancy Grand-Est and Institut de Recherche en Mathematiques Avancees, 7 rue Rene Descartes, F-67084 Strasbourg (France); Hervieux, P-A; Manfredi, G [Institut de Physique et Chimie des Materiaux de Strasbourg, 23 rue du Loess, F-67037 Strasbourg (France)], E-mail: morandi@dipmat.univpm.it

    2009-07-15

    We present a dynamical model that successfully explains the observed time evolution of the magnetization in diluted magnetic semiconductor quantum wells after weak laser excitation. Based on the pseudo-fermion formalism and a second-order many-particle expansion of the exact p-d exchange interaction, our approach goes beyond the usual mean-field approximation. It includes both the sub-picosecond demagnetization dynamics and the slower relaxation processes that restore the initial ferromagnetic order in a nanosecond timescale. In agreement with experimental results, our numerical simulations show that, depending on the value of the initial lattice temperature, a subsequent enhancement of the total magnetization may be observed within the timescale of a few hundred picoseconds.

  6. Metabolomics of Breast Cancer Using High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopy: Correlations with 18F-FDG Positron Emission Tomography-Computed Tomography, Dynamic Contrast-Enhanced and Diffusion-Weighted Imaging MRI.

    Directory of Open Access Journals (Sweden)

    Haesung Yoon

    Full Text Available Our goal in this study was to find correlations between breast cancer metabolites and conventional quantitative imaging parameters using high-resolution magic angle spinning (HR-MAS magnetic resonance spectroscopy (MRS and to find breast cancer subgroups that show high correlations between metabolites and imaging parameters.Between August 2010 and December 2013, we included 53 female patients (mean age 49.6 years; age range 32-75 years with a total of 53 breast lesions assessed by the Breast Imaging Reporting and Data System. They were enrolled under the following criteria: breast lesions larger than 1 cm in diameter which 1 were suspicious for malignancy on mammography or ultrasound (US, 2 were pathologically confirmed to be breast cancer with US-guided core-needle biopsy (CNB 3 underwent 3 Tesla MRI with dynamic contrast-enhanced (DCE and diffusion-weighted imaging (DWI and positron emission tomography-computed tomography (PET-CT, and 4 had an attainable immunohistochemistry profile from CNB. We acquired spectral data by HR-MAS MRS with CNB specimens and expressed the data as relative metabolite concentrations. We compared the metabolites with the signal enhancement ratio (SER, maximum standardized FDG uptake value (SUV max, apparent diffusion coefficient (ADC, and histopathologic prognostic factors for correlation. We calculated Spearman correlations and performed a partial least squares-discriminant analysis (PLS-DA to further classify patient groups into subgroups to find correlation differences between HR-MAS spectroscopic values and conventional imaging parameters.In a multivariate analysis, the PLS-DA models built with HR-MAS MRS metabolic profiles showed visible discrimination between high and low SER, SUV, and ADC. In luminal subtype breast cancer, compared to all cases, high SER, ADV, and SUV were more closely clustered by visual assessment. Multiple metabolites were correlated with SER and SUV in all cases. Multiple metabolites

  7. Magnetic resonance imaging texture analysis classification of primary breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Waugh, S.A.; Lerski, R.A. [Ninewells Hospital and Medical School, Department of Medical Physics, Dundee (United Kingdom); Purdie, C.A.; Jordan, L.B. [Ninewells Hospital and Medical School, Department of Pathology, Dundee (United Kingdom); Vinnicombe, S. [University of Dundee, Division of Imaging and Technology, Ninewells Hospital and Medical School, Dundee (United Kingdom); Martin, P. [Ninewells Hospital and Medical School, Department of Clinical Radiology, Dundee (United Kingdom); Thompson, A.M. [University of Texas MD Anderson Cancer Center, Department of Surgical Oncology, Houston, TX (United States)

    2016-02-15

    Patient-tailored treatments for breast cancer are based on histological and immunohistochemical (IHC) subtypes. Magnetic Resonance Imaging (MRI) texture analysis (TA) may be useful in non-invasive lesion subtype classification. Women with newly diagnosed primary breast cancer underwent pre-treatment dynamic contrast-enhanced breast MRI. TA was performed using co-occurrence matrix (COM) features, by creating a model on retrospective training data, then prospectively applying to a test set. Analyses were blinded to breast pathology. Subtype classifications were performed using a cross-validated k-nearest-neighbour (k = 3) technique, with accuracy relative to pathology assessed and receiver operator curve (AUROC) calculated. Mann-Whitney U and Kruskal-Wallis tests were used to assess raw entropy feature values. Histological subtype classifications were similar across training (n = 148 cancers) and test sets (n = 73 lesions) using all COM features (training: 75 %, AUROC = 0.816; test: 72.5 %, AUROC = 0.823). Entropy features were significantly different between lobular and ductal cancers (p < 0.001; Mann-Whitney U). IHC classifications using COM features were also similar for training and test data (training: 57.2 %, AUROC = 0.754; test: 57.0 %, AUROC = 0.750). Hormone receptor positive and negative cancers demonstrated significantly different entropy features. Entropy features alone were unable to create a robust classification model. Textural differences on contrast-enhanced MR images may reflect underlying lesion subtypes, which merits testing against treatment response. (orig.)

  8. Dynamic MRI of breast fibroadenoma: pathologic correlation

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Ki Keun; Hahm, Jin kyeung; Yoon, Pyong Ho; Jeong, Eun Kee [Yonsei University, College of Medicine, Seoul (Korea, Republic of)

    1995-09-15

    To analyze the dynamic MR imaging of breast fibroadenoma according to the histologic type for differentiation from breast carcinoma. Dynamic MR images of 26 lesions from 22 breasts in 19 patients showing atypical clinical features or film mammogram and ultrasound manifestations were performed. We analyzed the speed and the maximal amount of contrast enhancement and the patterns, such as shape, border, and internal signal intensity, among the histologic types during five minutes after contrast injection. The speed and maximal amount of contrast enhancement of fibroadenoma were in descending order of myxoid, sclerotic, glandular, and calcified types. Among these, the value of maximal amount of contrast enhancement of myxoid and sclerotic type were more than 700 NU, but only myxoid type was enhanced more than 700 NU within the first 1 minute after contrast injection, similar to the findings of carcinoma. In general, fibroadenoma showed the tendency of smooth surface(69%), well-defined border(88%) with safety rim, and internal homogeneous signal intensity(65%). However, sclerotic type of fibroadenoma had relatively high incidence of heterogeneous internal signal intensity(78%) after Gd-DTPA injection. Dynamic MR imaging of atypical breast fibroadenoma mimicking breast malignancy was very useful in differentiation it from carcinoma and had the benefit of classifying fibroadenoma according to its histologic types.

  9. Magnetic resonance imaging of the breast: A clinicial perspective

    Directory of Open Access Journals (Sweden)

    Jenny Edge

    2012-06-01

    Full Text Available The role of magnetic resonance imaging (MRI in screening for breast cancer and its use after the diagnosis of breast cancer is discussed. The topic is enormous, with over 5 000 papers published in the last 10 years. In this précis, we focused on articles that examine its clinical relevance. We did not look at economic factors.

  10. Mercury's Dynamic Magnetic Tail

    Science.gov (United States)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

  11. Breast magnetic resonance imaging in patients with occult breast carcinoma: evaluation on feasibility and correlation with histopathological findings

    Institute of Scientific and Technical Information of China (English)

    LU Hong; XU Yi-lin; ZHANG Shu-ping; LANG Rong-gang; Chi S.Zee; LIU Pei-fang; FU Li

    2011-01-01

    Background As an uncommon presentation, occult primary breast cancer remains a diagnostic and therapeutic challenge in clinical practice. This study aimed to retrospectively assess the feasibility of breast magnetic resonance imaging (MRI) in patients with malignant axillary lymphadenopathy and unknown primary malignancy, and correlation with histopathological characteristics.Methods A total of 35 women with occult breast carcinoma were evaluated with dynamic contrast-enhanced breast MRI. Whole seriate section was used in all cases. MRI performance was assessed and correlated with histopathological findings.Results Twenty-one of 35 patients were found to have primary breast carcinoma histologically. Twenty of the 21 patients had abnormal MR findings and 1 patient had a normal MRI study. Of the remaining 14 patients, 10 were negative on both MRI and surgery. Four had suspicious enhancement on MRI and no corresponding tumor was found. Lesions with mass enhancement were found in 55% (11/20) and ductual and segmental enhancement in 45%. The average diameter of the primary tumors was 15 mm. Invasive ductal carcinomas were found in 81% (17/21). One of 17 invasive ductual carcinomas was too small to be graded. Fourteen of the remaining 16 were classified as grade II and 2 as grade I. Thirty-two of the 35 patients had received estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 examinations and the 12 of 32 were triple-negative breast carcinoma.Conclusions Mass lesions with small size and lesions with ductal or segment enhancement are common MRI features in patients with occult breast cancer. The dominant types of primary tumors are invasive ductal carcinoma with moderate histopathological grade. The rate of triple-negative breast carcinoma may be higher in occult breast cancer.

  12. Magnetic droplets and dynamical skyrmions

    Science.gov (United States)

    Akerman, Johan

    2015-03-01

    Nanocontact spin-torque oscillators (NC-STOs) provide an excellent environment for studying nano-magnetic phenomena such as localized and propagating auto-oscillatory spin wave (SW) modes. The recent experimental observation of magnetic droplet solitons in NC-STOs with perpendicular magnetic anisotropy (PMA) free layers, and the numerical and experimental demonstrations of spin transfer torque (STT) nucleated skyrmions in similar magnetic thin films add two interesting and useful nanoscale magnetic objects. Due to the competition between exchange, anisotropy, and, in the case of skyrmions, the Dzyaloshinskii-Moriya interaction (DMI), the droplet and the skyrmion are extremely compact, on the order of 10-100 nm. One of the main differences between a magnetic dissipative droplet soliton and a skyrmion is that the former is a dynamical object with all its spins precessing around an effective field and stabilized by STT, exchange, and PMA, while the latter has static spins and an internal structure stabilized by DMI, exchange, and PMA. The dissipative droplet is furthermore a non-topological soliton, while the skyrmion is topologically protected. In this work I will report on our most recent droplet experiments, including droplet collapse at very high fields, droplets excited in nano-wire based NC-STOs, and studies of the field-current droplet nucleation boundary. I will also demonstrate numerically and analytically that STT driven precession can stabilize so-called dynamical skyrmions even in the absence of DMI, and I will describe their very promising properties in detail. From a more fundamental perspective, precession is hence a third independent possibility to stabilize a skyrmion, without the need for the conventional stabilization from either dipolar energy or DMI.

  13. Automated breast segmentation of fat and water MR images using dynamic programming.

    Science.gov (United States)

    Rosado-Toro, José A; Barr, Tomoe; Galons, Jean-Philippe; Marron, Marilyn T; Stopeck, Alison; Thomson, Cynthia; Thompson, Patricia; Carroll, Danielle; Wolf, Eszter; Altbach, María I; Rodríguez, Jeffrey J

    2015-02-01

    To develop and test an algorithm that outlines the breast boundaries using information from fat and water magnetic resonance images. Three algorithms were implemented and tested using registered fat and water magnetic resonance images. Two of the segmentation algorithms are simple extensions of the techniques used for contrast-enhanced images: one algorithm uses clustering and local gradient (CLG) analysis and the other algorithm uses a Hessian-based sheetness filter (HSF). The third segmentation algorithm uses k-means++ and dynamic programming (KDP) for finding the breast pixels. All three algorithms separate the left and right breasts using either a fixed region or a morphological method. The performance is quantified using a mutual overlap (Dice) metric and a pectoral muscle boundary error. The algorithms are evaluated against three manual tracers using 266 breast images from 14 female subjects. The KDP algorithm has a mean overlap percentage improvement that is statistically significant relative to the HSF and CLG algorithms. When using a fixed region to remove the tissue between breasts with tracer 1 as a reference, the KDP algorithm has a mean overlap of 0.922 compared to 0.864 (P algorithm is independent of breast density. We developed a new automated segmentation algorithm (KDP) to isolate breast tissue from magnetic resonance fat and water images. KDP outperforms the other techniques that focus on local analysis (CLG and HSF) and yields a performance similar to human tracers. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  14. Evaluation of magnetization transfer ratios for breast tissues and breast diseases

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Fumio; Murai, Hiroshi; Takeuchi, Thouru; Iwase, Takuji; Miura, Shigeto; Mastushima, Shigeru; Oosaki, Hikaru [Aichi Cancer Center, Nagoya (Japan). Hospital; Kinosada, Yasuomi

    1997-03-01

    To determine MTRs for normal structures and benign diseases in the breast two-dimensional magnetization transfer imaging was performed in 62 patients and in 3 young female volunteers. With regard to the MTRs of measurements in the normal breast tissues, fat tissues which is close to simple cysts in MTRs show little transfer of longitudinal magnetization. MTRs of the muscles was 15.15{+-}6.22%, which exceeded those of breast parenchyma. The breast parenchyma didn`t show the change of MTR value due to the difference of patient age and due to variable amount of fat and fibrous tissues. Breast parenchyma in the two young volunteers clearly showed biphasic change of MTR values in accordance with the menstrual cycle; little transfer value was due to hydration in the postovulatory period and high transfer value was due to dehydration in the preovulatory period. In the remaining one volunteer during lactation period, mammary parenchyma shows sever decrease in MTR, because mammary gland is loaded with massive fluid, showing a very high signal intensity on First IR and T2-weighted images. MTR values of benign breast diseases including mastopathy, fibroadenoma and phyllodes tumor had no significant difference from those of the breast parenchyma and muscle. Non-invasive ductal carcinoma was equivalent to breast parenchyma in MTR. (K.H.)

  15. Magnetic resonance imaging appearances in primary and secondary angiosarcoma of the breast.

    LENUS (Irish Health Repository)

    O'Neill, Ailbhe C

    2014-04-01

    Angiosarcomas are malignant tumours of endovascular origin. They are rare tumours accounting for 0.04-1% of all breast malignancies. Two different forms are described: primary, occurring in young women, and secondary angiosarcoma, which occurs in older women with a history of breast-conserving surgery and radiation therapy. Imaging findings on mammography and ultrasound are non-specific, but magnetic resonance imaging with dynamic contrast enhancement is more informative. We present two cases - one of primary and one of secondary angiosarcoma - and review the imaging findings.

  16. Implantable magnetic nanocomposites for the localized treatment of breast cancer

    Science.gov (United States)

    Kan-Dapaah, Kwabena; Rahbar, Nima; Soboyejo, Wole

    2014-12-01

    This paper explores the potential of implantable magnetic nanocomposites for the localized treatment of breast cancer via hyperthermia. Magnetite (Fe3O4)-reinforced polydimethylsiloxane composites were fabricated and characterized to determine their structural, magnetic, and thermal properties. The thermal properties and degree of optimization were shown to be strongly dependent on material properties of magnetic nanoparticles (MNPs). The in-vivo temperature profiles and thermal doses were investigated by the use of a 3D finite element method (FEM) model to simulate the heating of breast tissue. Heat generation was calculated using the linear response theory model. The 3D FEM model was used to investigate the effects of MNP volume fraction, nanocomposite geometry, and treatment parameters on thermal profiles. The implications of the results were then discussed for the development of implantable devices for the localized treatment of breast cancer.

  17. Breast Magnetic Resonance Imaging Findings in Women Treated with Toremifene for Premenstrual Mastalgia

    Energy Technology Data Exchange (ETDEWEB)

    Oksa, S. (Dept. of Obstetrics and Gynecology, Satakunta Central Hospital, Pori (Finland)); Parkkola, R. (Dept. of Radiology, Univ. Hospital of Turku, Turku (Finland)); Luukkaala, T.; Maeenpaeae, J. (Medical School, Univ. of Tampere, Tampere (Finland))

    2009-11-15

    Background: Toremifene, a selective estrogen receptor modulator, has been shown to be effective in alleviating premenstrual breast pain. However, the exact mechanism by which toremifene and related compounds work in premenstrual mastalgia is poorly understood. Purpose: To find out if the effect of toremifene on breast would be detectable with dynamic magnetic resonance imaging (MRI). Material and Methods: This randomized, double-blind crossover study was performed on women suffering from marked premenstrual mastalgia. Ten women were randomized to receive either toremifene (20 mg) or placebo from cycle day 15 until next menstruation for three menstrual cycles. After a washout period, the treatment was crossed over for three additional cycles. The MRI evaluations were performed premenstrually at the end of each treatment phase. Breast pain and quality-of-life scores were collected from one baseline cycle and from all the treatment cycles. Results: Nine patients were evaluable for this analysis. Both the enhancement ratio and the maximum slope of enhancement tended to be smaller during the toremifene cycles as compared to placebo. On the left side, the difference in the maximum slope of enhancement between toremifene and placebo was statistically significant (median 5.150 [range 3.7-6.7] and 6.500 [range 4.9-9.5], respectively; P=0.047). T2 relaxation times as well as breast pain and quality-of-life scores were inconsistent. Conclusion: Use of toremifene is associated with measurable changes in dynamic breast MRI findings in women with cyclic breast pain

  18. Dynamic MRI study for breast tumors

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Tsuneaki (Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine)

    1990-10-01

    Application of MRI for diagnosis of breast tumors was retrospectively examined in 103 consecutive cases. Contrast enhancement, mostly by dynamic study, was performed in 83 cases using Gd-DTPA and 0.5 T superconductive apparatus. Results were compared to those of mammography and sonography. On dynamic study, carcinoma showed abrupt rise of signal intensity with clear-cut peak formation in early phase, while benign fibroadenoma showed slow rise of signal intensity and prolonged enhancement without peak formation. In 12 of 33 carcinomas (33%), peripheral ring enhancement was noted reflecting vascular stroma of histologic sections. All fibroadenomas showed homogenous enhancement without peripheral ring. In MRI, sensitivity, specificity, and accuracy were 86%, 96%, 91%. In mammography 82%, 95%, 87% and in ultrasonography 91%, 95%, 93%. Although MRI should not be regarded as routine diagnostic procedure because of expense and limited availability, it may afford useful additional information when standard mammographic findings are not conclusive. (author).

  19. Breast Density Analysis with Automated Whole-Breast Ultrasound: Comparison with 3-D Magnetic Resonance Imaging.

    Science.gov (United States)

    Chen, Jeon-Hor; Lee, Yan-Wei; Chan, Si-Wa; Yeh, Dah-Cherng; Chang, Ruey-Feng

    2016-05-01

    In this study, a semi-automatic breast segmentation method was proposed on the basis of the rib shadow to extract breast regions from 3-D automated whole-breast ultrasound (ABUS) images. The density results were correlated with breast density values acquired with 3-D magnetic resonance imaging (MRI). MRI images of 46 breasts were collected from 23 women without a history of breast disease. Each subject also underwent ABUS. We used Otsu's thresholding method on ABUS images to obtain local rib shadow information, which was combined with the global rib shadow information (extracted from all slice projections) and integrated with the anatomy's breast tissue structure to determine the chest wall line. The fuzzy C-means classifier was used to extract the fibroglandular tissues from the acquired images. Whole-breast volume (WBV) and breast percentage density (BPD) were calculated in both modalities. Linear regression was used to compute the correlation of density results between the two modalities. The consistency of density measurement was also analyzed on the basis of intra- and inter-operator variation. There was a high correlation of density results between MRI and ABUS (R(2) = 0.798 for WBV, R(2) = 0.825 for PBD). The mean WBV from ABUS images was slightly smaller than the mean WBV from MR images (MRI: 342.24 ± 128.08 cm(3), ABUS: 325.47 ± 136.16 cm(3), p MRI: 24.71 ± 15.16%, ABUS: 28.90 ± 17.73%, p breast density measurement variation between the two modalities. Our results revealed a high correlation in WBV and BPD between MRI and ABUS. Our study suggests that ABUS provides breast density information useful in the assessment of breast health.

  20. Multifractal analysis of dynamic infrared imaging of breast cancer

    Science.gov (United States)

    Gerasimova, E.; Audit, B.; Roux, S. G.; Khalil, A.; Argoul, F.; Naimark, O.; Arneodo, A.

    2013-12-01

    The wavelet transform modulus maxima (WTMM) method was used in a multifractal analysis of skin breast temperature time-series recorded using dynamic infrared (IR) thermography. Multifractal scaling was found for healthy breasts as the signature of a continuous change in the shape of the probability density function (pdf) of temperature fluctuations across time scales from \\sim0.3 to 3 s. In contrast, temperature time-series from breasts with malignant tumors showed homogeneous monofractal temperature fluctuations statistics. These results highlight dynamic IR imaging as a very valuable non-invasive technique for preliminary screening in asymptomatic women to identify those with risk of breast cancer.

  1. Diagnosis of breast tumors with 1H-MRS and dynamic contrast-enhanced magnetic resonance imaging%联合应用1H-MRS与MR动态增强成像诊断乳腺肿瘤

    Institute of Scientific and Technical Information of China (English)

    周欣; 张婷婷; 胡国清

    2012-01-01

    Objective To compare the value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) alone and combined with 1 H-MRS in diagnosis of breast tumors. Methods ' H-MRS and DCE-MRI of 50 patients with breast tumors including 33 malignant lesions and 17 benign lesions were retrospectively analyzed. The diagnostic results of ' H-MRS and DCE-MRI were compared with pathological and clinical follow-up results. All patients underwent pre-enhanced conventional scanning, 1 H-MRS scanning and DCE-MR scanning after injection of contrast agent. The type of time-intensity curves (TIC) and display of choline (Cho) peak for all lesions were calculated. Results The diagnostic sensitivity, specificity and accuracy rate for TIC alone was 100% (33/33), 58. 82% (10/17) and 66. 00% (33/50), respectively, while was 100% (33/33), 88.24% (15/17) and 96.00% (48/50) respectively for combined application of 1H-MRS and DCE-MRI. There was statistical difference in diagnostic specificity and accuracy rate between the two methods (both P<0. 02). Conclusion DCE-MRI has lower specificity and accuracy rate for diagnosis of breast tumors. Combination of ' H-MRS and DCE-MRI can improve the diagnostic accuracy rate of breast tumors.%目的 比较应用MR动态增强成像(DCE-MRI)与联合应用1H-MRS及DCE-MRI对乳腺肿瘤的诊断价值.方法 回顾性分析50例乳腺肿瘤患者的1H-MRS及DCE-MRI表现,包括恶性肿瘤33例,良性肿瘤17例,并与病理及临床随诊结果进行对比.对所有患者分别行常规扫描、1H-MRS扫描及注射对比剂后动态增强扫描,分析时间-信号曲线(TIC)类型和胆碱(Cho)峰的显示情况.结果 以TIC类型判断肿瘤的良恶性,诊断的敏感度为100%(33/33),特异度为58.82%(10/17),准确率为66.00%(33/50);应用1H-MRS联合DCE-MRI诊断的敏感度为100%(33/33),特异度为88.24%(15/17),准确率为96.00%(48/50),与单纯DCE-MRI诊断的特异度和准确率差异有统计学意义(P均<0.02).结论 DCE

  2. Magnetic Resonance (MR)-Guided Breast Biopsy

    Science.gov (United States)

    ... large cylinder-shaped tube surrounded by a circular magnet. You will lie on a moveable examination table that slides into the center of the magnet. Some MRI units, called short-bore systems , are ...

  3. Effects of heat current on magnetization dynamics

    Science.gov (United States)

    Vetro, Francesco Antonio; Brechet, Sylvain; Ansermet, Jean-Philippe

    The work is aimed at investigating the interplay between spin dynamics and heat currents in single-crystal Yttrium Iron Garnet (YIG). The irreversible thermodynamics for a continuous medium predicts that a thermal gradient, in the presence of magnetization waves, produces a magnetic induction field, thus a magnetic analog of the well-known Seebeck effect. Time-resolved transmission measurements revealed a change in the attenuation of magnetization waves propagating along the thermal gradient when the gradient is reversed. This magnetic damping change can be accounted for by the Magnetic Seebeck effect. In order to characterize this effect further, we have conducted studies on magnetization dynamic in YIG single crystal samples placed in various geometrical configurations, e.g. with YIG disks in which magnetic vortices might be present. Various magnetic resonance schemes were used, e.g. local probes and cavities.

  4. Dynamics of Rotating, Magnetized Neutron Stars

    OpenAIRE

    Liebling, Steven L.

    2010-01-01

    Using a fully general relativistic implementation of ideal magnetohydrodynamics with no assumed symmetries in three spatial dimensions, the dynamics of magnetized, rigidly rotating neutron stars are studied. Beginning with fully consistent initial data constructed with Magstar, part of the Lorene project, we study the dynamics and stability of rotating, magnetized polytropic stars as models of neutron stars. Evolutions suggest that some of these rotating, magnetized stars may be minimally uns...

  5. Differentiation of breast cancer from fibroadenoma with dual-echo dynamic contrast-enhanced MRI.

    Directory of Open Access Journals (Sweden)

    Shiwei Wang

    Full Text Available Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI of the breast is a routinely used imaging method which is highly sensitive for detecting breast malignancy. Specificity, though, remains suboptimal. Dynamic susceptibility contrast magnetic resonance imaging (DSC MRI, an alternative dynamic contrast imaging technique, evaluates perfusion-related parameters unique from DCE MRI. Previous work has shown that the combination of DSC MRI with DCE MRI can improve diagnostic specificity, though an additional administration of intravenous contrast is required. Dual-echo MRI can measure both T1W DCE MRI and T2*W DSC MRI parameters with a single contrast bolus, but has not been previously implemented in breast imaging. We have developed a dual-echo gradient-echo sequence to perform such simultaneous measurements in the breast, and use it to calculate the semi-quantitative T1W and T2*W related parameters such as peak enhancement ratio, time of maximal enhancement, regional blood flow, and regional blood volume in 20 malignant lesions and 10 benign fibroadenomas in 38 patients. Imaging parameters were compared to surgical or biopsy obtained tissue samples. Receiver operating characteristic (ROC curves and area under the ROC curves were calculated for each parameter and combination of parameters. The time of maximal enhancement derived from DCE MRI had a 90% sensitivity and 69% specificity for predicting malignancy. When combined with DSC MRI derived regional blood flow and volume parameters, sensitivity remained unchanged at 90% but specificity increased to 80%. In conclusion, we show that dual-echo MRI with a single administration of contrast agent can simultaneously measure both T1W and T2*W related perfusion and kinetic parameters in the breast and the combination of DCE MRI and DSC MRI parameters improves the diagnostic performance of breast MRI to differentiate breast cancer from benign fibroadenomas.

  6. Digital optical tomography system for dynamic breast imaging.

    Science.gov (United States)

    Flexman, Molly L; Khalil, Michael A; Al Abdi, Rabah; Kim, Hyun K; Fong, Christopher J; Desperito, Elise; Hershman, Dawn L; Barbour, Randall L; Hielscher, Andreas H

    2011-07-01

    Diffuse optical tomography has shown promising results as a tool for breast cancer screening and monitoring response to chemotherapy. Dynamic imaging of the transient response of the breast to an external stimulus, such as pressure or a respiratory maneuver, can provide additional information that can be used to detect tumors. We present a new digital continuous-wave optical tomography system designed to simultaneously image both breasts at fast frame rates and with a large number of sources and detectors. The system uses a master-slave digital signal processor-based detection architecture to achieve a dynamic range of 160 dB and a frame rate of 1.7 Hz with 32 sources, 64 detectors, and 4 wavelengths per breast. Included is a preliminary study of one healthy patient and two breast cancer patients showing the ability to identify an invasive carcinoma based on the hemodynamic response to a breath hold.

  7. Surface magnetic domains dynamic in machined steel

    Directory of Open Access Journals (Sweden)

    Blažek D.

    2014-07-01

    Full Text Available This contribution deals with an observation of the magnetic dynamic of different types of the machined surface of bearing steel. The Bakhausen noise (BN measurements are presented here as commonly introduced in industry for quality control due to the extremely sensitivity of the magnetic domains wall dynamics to the microstructure of material. The results of magneto-optical measurements are presented with the goal to explain the observed BN anisotropy. It is shown that BN anisotropy is associated with uniaxal magnetic anisotropy introduced by hard milling which causes the principally different magnetic reversals processes in orthogonal directions.

  8. [The actions of diffusion weighted imaging (DWI) and dynamic contrast enhanced MRI in differentiating breast tumors].

    Science.gov (United States)

    Luo, Yi; Yu, Jianqun; Chen, Dongdong; Xu, Zhongzi; Zeng, Hanjiang

    2013-12-01

    We studied the actions of diffusion weighted imaging (DWI) and dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) in differentiating breast tumors. From January 2010 to February 2012, we retrospectively analyzed data of 95 cases with breast tumor pathologically confirmed from DWI and DCE-MRI. We compared the ADC value, time-intensity curve (TIC) and DCE-MRI parameters between breast tumors, and calculated the sensitivity and specificity for differentiating breast tumors. The results were as follows: (1) On DWI, mean ADC value of malignant tumor was lower than that of benign tumor (P value of time to peak (Tpeak) and maximal enhancement ratio (SImax) were lower than that of benign tumor (all P < 0.05). As for TIC, type II and III were more frequently seen in malignant tumor than in benign tumor whereas type I was more common in benign tumor than in malignant tumor (all P < 0.05). For differentiating breast malignant tumors from benign neoplasm, DCE-MRI obtained a sensitivity of 89.7% and specificity of 70.3%. (3) For differentiating breast malignant tumors from benign neoplasm, ADC value together with TIC obtained a sensitivity of 79.3% and specificity of 78.4%. Malignant or benign breast tumors could have their own unique characteristics on DWI and DCE-MRI. These characteristics might be helpful for differentiating these tumors.

  9. Undulator with dynamic compensation of magnetic forces

    Energy Technology Data Exchange (ETDEWEB)

    Gluskin, Efim; Trakhtenberg, Emil; Xu, Joseph Z.

    2016-05-31

    A method and apparatus for implementing dynamic compensation of magnetic forces for undulators are provided. An undulator includes a respective set of magnet arrays, each attached to a strongback, and placed on horizontal slides and positioned parallel relative to each other with a predetermined gap. Magnetic forces are compensated by a set of compensation springs placed along the strongback. The compensation springs are conical springs having exponential-force characteristics that substantially match undulator magnetic forces independently of the predetermined gap. The conical springs are positioned along the length of the magnets.

  10. Undulator with dynamic compensation of magnetic forces

    Science.gov (United States)

    Gluskin, Efim; Trakhtenberg, Emil; Xu, Joseph Z.

    2016-05-31

    A method and apparatus for implementing dynamic compensation of magnetic forces for undulators are provided. An undulator includes a respective set of magnet arrays, each attached to a strongback, and placed on horizontal slides and positioned parallel relative to each other with a predetermined gap. Magnetic forces are compensated by a set of compensation springs placed along the strongback. The compensation springs are conical springs having exponential-force characteristics that substantially match undulator magnetic forces independently of the predetermined gap. The conical springs are positioned along the length of the magnets.

  11. Counterview: Pre-operative breast MRI (magnetic resonance imaging) is not recommended for all patients with newly diagnosed breast cancer.

    Science.gov (United States)

    Solin, Lawrence J

    2010-02-01

    For the woman with a newly diagnosed early stage breast cancer, the routine use of pre-operative breast MRI (magnetic resonance imaging) is not indicated beyond conventional breast imaging (i.e., mammography with correlation ultrasound as indicated). There is no consistent evidence that a pre-operative breast MRI confers a benefit to the patient by improving clinical outcomes or surgical procedures. In a meta-analysis of studies reporting on the use of pre-operative breast MRI for the patient with an established index cancer, multifocal or multicentric disease was found on breast MRI in 16% of the patients, a rate substantially higher than the rate of local recurrence after breast conserving surgery plus definitive radiation treatment. In the largest retrospective study of patients treated with breast conserving surgery plus radiation, no gain was found for adding a breast MRI to conventional breast imaging. No randomized clinical trial has been designed to evaluate long term clinical outcomes associated with adding a pre-operative breast MRI. Adding pre-operative breast MRI can alter clinical management in ways that are potentially harmful to patients, for example, increased ipsilateral mastectomies, increased contralateral prophylactic mastectomies, increased work-ups, and delay to definitive surgery. In summary, the routine use of pre-operative breast MRI is not warranted for the typical patient with a newly diagnosed early stage breast cancer.

  12. How I report breast magnetic resonance imaging studies for breast cancer staging and screening.

    Science.gov (United States)

    Vinnicombe, Sarah

    2016-07-25

    Magnetic resonance imaging (MRI) of the breast is the most sensitive imaging technique for the diagnosis and local staging of primary breast cancer and yet, despite the fact that it has been in use for 20 years, there is little evidence that its widespread uncritical adoption has had a positive impact on patient-related outcomes.This has been attributed previously to the low specificity that might be expected with such a sensitive modality, but with modern techniques and protocols, the specificity and positive predictive value for malignancy can exceed that of breast ultrasound and mammography. A more likely explanation is that historically, clinicians have acted on MRI findings and altered surgical plans without prior histological confirmation. Furthermore, modern adjuvant therapy for breast cancer has improved so much that it has become a very tall order to show a an improvement in outcomes such as local recurrence rates.In order to obtain clinically useful information, it is necessary to understand the strengths and weaknesses of the technique and the physiological processes reflected in breast MRI. An appropriate indication for the scan, proper patient preparation and good scan technique, with rigorous quality assurance, are all essential prerequisites for a diagnostically relevant study.The use of recognised descriptors from a standardised lexicon is helpful, since assessment can then dictate subsequent recommendations for management, as in the American College of Radiology BI-RADS (Breast Imaging Reporting and Data System) lexicon (Morris et al., ACR BI-RADS® Atlas, Breast Imaging Reporting and Data System, 2013). It also enables audit of the service. However, perhaps the most critical factor in the generation of a meaningful report is for the reporting radiologist to have a thorough understanding of the clinical question and of the findings that will influence management. This has never been more important than at present, when we are in the throes of a

  13. The role of breast magnetic resonance imaging in the diagnosis of ductal carcinoma in situ

    Directory of Open Access Journals (Sweden)

    Nadrljanski Mirjan

    2013-01-01

    Full Text Available Ductal carcinoma in situ (DCIS, the noninvasive breast malignant tumor originates from the terminal ductal­lobular units (TDLU. The typical feature of DCSI is the formation of calcifications. Up to 90% of DCIS are diagnosed on mammographic examinations, as clinically asymptomatic. Between 10% and 20% of DCIS remain mammographically occult due to the lack of calcifications and/ or small tumor dimensions. Contrast­enhanced breast magnetic resonance imaging (MRI detects mammographically occult breast lesions, thus defining morphologic features of the lesion and the dynamics of signal intensity changes due to contrast enhancement. Distribution of contrast enhancement - signal intensity increase in DCIS most frequently includes segmental, ductal and linear patterns, followed by regional enhancement pattern, while the intralesional contrast uptake most frequently includes the nodular pattern with the areas of confluence. Post­ contrast signal intensity increase in DCIS is most frequently fast in the initial phase (wash­in, while the whole dynamic of contrast­enhancement includes either of the three possible time­intensity curve (TIC types (persistent, plateau or washout, although the plateau TIC is considered to be more frequent. Breast MRI has high sensitivity in the diagnosis of invasive breast cancer, varying from 90% to 100%; the sensitivity in the diagnosis of DCIS is lower (77­96%. For the time being, the primary role of MRI in DCIS is planning of breast­conserving surgery (BCS for the evaluation of lesion extension. Further development of MRI in the diagnosis of DCIS includes the implementation of the principles of functional and molecular imaging.

  14. Dynamics of Permanent-Magnet Biased Active Magnetic Bearings

    Science.gov (United States)

    Fukata, Satoru; Yutani, Kazuyuki

    1996-01-01

    Active magnetic radial bearings are constructed with a combination of permanent magnets to provide bias forces and electromagnets to generate control forces for the reduction of cost and the operating energy consumption. Ring-shaped permanent magnets with axial magnetization are attached to a shaft and share their magnet stators with the electromagnets. The magnet cores are made of solid iron for simplicity. A simplified magnetic circuit of the combined magnet system is analyzed with linear circuit theory by approximating the characteristics of permanent magnets with a linear relation. A linearized dynamical model of the control force is presented with the first-order approximation of the effects of eddy currents. Frequency responses of the rotor motion to disturbance inputs and the motion for impulsive forces are tested in the non-rotating state. The frequency responses are compared with numerical results. The decay of rotor speed due to magnetic braking is examined. The experimental results and the presented linearized model are similar to those of the all-electromagnetic design.

  15. Magnetic Resonance Imaging of Breast Cancer and Correlation with Prognostic Factors

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yun-Woo; Kwon, Kui Hyang; Choi, Deuk Lin; Lee, Dong Wha; Lee, Min Hyuk (College of Medicine, Soonchunhyang Univ. Hospital, Seoul (Korea)); Lee, Hye Kyung (Dept. of Radiology, Soonchunhyang Bucheon Hospital, Kyonggi (Korea)); Yang, Seung Boo (Dept. of Radiology, Soonchunhyang Gumi Hospital, Kyungbook (Korea)); Kim, Yongbae (Dept. of Preventive Medicine, Soonchunhyang Univ., Chungnam (Korea)); Seo, Dae Young (Dept. of Computer Engineering (KO) Polytechnic Univ., Kyonggi (Korea))

    2009-11-15

    Background: Prognostic factors of breast cancer have been used for the prediction of clinical outcome or selection of patients for complementary treatment. Some of the imaging features of breast cancer, e.g. magnetic resonance imaging (MRI), are associated with these prognostic factors. Purpose: To evaluate the relationship between dynamic enhanced MR features and prognostic factors of clinical outcome of breast cancer. Material and Methods: A total of 136 patients with 151 breast cancers underwent 1.5T dynamic MR imaging with the use of a dynamic T1-weighted three-dimensional fast low-angle shot (FLASH) subtraction imaging technique. Morphological and kinetic analyses of MR features were evaluated using the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) MRI lexicon. Pathological prognostic factors were correlated with MR imaging characteristics, including tumor size, histological grade, lymph node status, expression of estrogen receptor (ER), expression of progesterone receptor (PR), expression of c-erbB2, determination of Ki-67 index, and microvascular density (MVD), using univariate and multivariate statistical analyses. Results: Based on univariate and multivariate analyses, spiculated tumor margins correlated significantly with lower histological grade (I-II) and positive PR expression. Rim enhancement was significantly correlated with high histological grade, presence of axillary lymph node metastasis, large tumor size, increased Ki-67 index, and increased MVD. Early peak enhancement, as seen on the first scan after contrast medium injection, was correlated with negative ER expression. Conclusion: The presence of a lesion with a spiculated margin may predict a relatively good prognosis, and the presence of a lesion with rim enhancement may predict a relatively poor prognosis

  16. Cholestrol granuloma of the breast incidentally detected on dynamic abdominal CT: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Sun Hye; Lee, Eun Hye; Hong, Hyun Sook; Kwak, Jeong Ja [Soonchunhyang University College of Medicine, Bucheon Hospital, Bucheon (Korea, Republic of)

    2016-01-15

    A breast cholesterol granuloma is an uncommon nodular breast lesion. We incidentally detected a persistently enhancing breast mass on the dynamic abdominal computed tomography (CT) of a 78-year-old woman. The mass decreased in diameter over 50 days following a core needle biopsy. This report is the first to describe the dynamic-enhanced CT features of a breast cholesterol granuloma.

  17. Nonlinear Dynamics of A Damped Magnetic Oscillator

    CERN Document Server

    Kim, S Y

    1999-01-01

    We consider a damped magnetic oscillator, consisting of a permanent magnet in a periodically oscillating magnetic field. A detailed investigation of the dynamics of this dissipative magnetic system is made by varying the field amplitude $A$. As $A$ is increased, the damped magnetic oscillator, albeit simple looking, exhibits rich dynamical behaviors such as symmetry-breaking pitchfork bifurcations, period-doubling transitions to chaos, symmetry-restoring attractor-merging crises, and saddle-node bifurcations giving rise to new periodic attractors. Besides these familiar behaviors, a cascade of ``resurrections'' (i.e., an infinite sequence of alternating restabilizations and destabilizations) of the stationary points also occurs. It is found that the stationary points restabilize (destabilize) through alternating subcritical (supercritical) period-doubling and pitchfork bifurcations. We also discuss the critical behaviors in the period-doubling cascades.

  18. Dynamical properties of unconventional magnetic systems

    Energy Technology Data Exchange (ETDEWEB)

    Helgesen, G. [ed.

    1997-05-01

    The Advanced Study Institute addressed the current experimental and theoretical knowledge of the dynamical properties of unconventional magnetic systems including low-dimensional and mesoscopic magnetism, unconventional ground state, quantum magnets and soft matter. The main approach in this Advanced Study Institute was to obtain basic understanding of co-operative phenomena, fluctuations and excitations in the wide range unconventional magnetic systems now being fabricated or envisioned. The report contains abstracts for lectures, invited seminars and posters, together with a list of the 95 participants from 24 countries with e-mail addresses

  19. Schwannoma of the breast: an unexpected diagnosis by magnetic resonance.

    Science.gov (United States)

    Solano Díaz, P; Hidalgo Martín, M T; Sánchez Cordero, M F; Soto Aguilar, M C

    2017-04-28

    Schwannomas consist of benign tumors that arise from the nerves, however, they are not frequent in the breast. Our search criteria only found 28 cases described in Literature. We show the case about a 63 years old woman who underwent a breast magnetic resonance (MR) because of high risk for breast cancer, in which a lession on her left breast was found. Not only MR features seemed to be benign, but ultrasound and mamography features, too. The diagnosis of schwannoma was confirmed by ultrasound-guided biopsy. Findings in conventional radiology were correlated with those described in the reviewed literature. In our opinion, this case results valuable due to the inicial diagnosis by MR, which is not an imaging proof for bening tumors, innitially. According to the revised bibliography these features are pretty funny, as mamography and ultrasound, with histological findings, are the clues for the usual diagnosis. Copyright © 2017 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

  20. Magnetic resonance imaging of trilucent TM breast implants

    Energy Technology Data Exchange (ETDEWEB)

    Elson, Elspeth M.; Jones, Annette; King, Rebecca; Chapman, P.; Stanek, Jan; Irvine, Allan T.; Bingham, John B

    2002-04-01

    AIM: To demonstrate the magnetic resonance imaging (MRI) appearances of intact and ruptured Trilucent TM implants with imaging and surgical correlation. The appearances of the implant transponder artefact are also described MATERIALS AND METHODS: A retrospective review of the MRI findings in 34 patients with bilateral subpectoral Trilucent TM breast implants (Lipomatrix, Inc./Collagen Aesthetics International Inc., Neuchatel, Switzerland) was performed. Patients under implant surveillance and those with suspected implant rupture formed the study group. Imaging findings were correlated with surgical appearances. RESULTS: Surgical correlation was available in 53% of patients. Fifty per cent (18/36) of implants were intact at surgery, 50% (18/36) of implants were ruptured. Of the 18 ruptured implants, 17 were intracapsular ruptures and one an extracapsular rupture. The sensitivity of MRI for detection of intracapsular rupture in Trilucent TM breast implants was 82% specificity 76%, positive predictive value 78%, negative predictive value 81% and accuracy 79% in this study group. No case of implant rupture was obscured by the transponder artefact. Four implants were found to have 'pseudocapsules' at surgery (5{center_dot}9%), the implants were intact with fluid present between the implant and capsule. Only one pseudocapsule was demonstrated on MRI. CONCLUSION: Magnetic resonance imaging is currently the most accurate technique for diagnosis of implant rupture in Trilucent TM breast implants. Transponder artefact does not appear to interfere with the assessment of implant rupture. Elson, E. M. et al. (2002)

  1. Computerized Interpretation of Dynamic Breast MRI

    Science.gov (United States)

    2006-05-01

    planning , and treatment response monitoring. X-Ray mammography has shown considerable success in screening for the early detection of breast cancer; however...observer is highly accurate (8) Automatic tumor delineation is of clinical value, for example, in surgical planning or follow-up during neoad- juvant... Venta LA, Vyborny CJ. Automatic segmentation of breast lesions on ultrasound. Med Phys 2001; 28:1652–1659. 14. Madabhushi A, Metaxas DN. Combining low

  2. Dynamic shielding of the magnetic fields

    Directory of Open Access Journals (Sweden)

    RAU, M.

    2010-11-01

    Full Text Available The paper presents a comparative study of the methods used to control and compensate the direct and alternative magnetic fields. Two frequently used methods in the electromagnetic compatibility of the complex biomagnetism installations were analyzed. The two methods refer to the use of inductive magnetic field sensors (only for alternative fields and of fluxgate magnetometers as active transducers which measures both the direct and alternative components of the magnetic field. The applications of the dynamic control of the magnetic field are: control of the magnetic field of the military ships, control of parasite magnetic field produced by power transformers and the electrical networks, protection of the mass spectrometers, electronic microscopes, SQUID and optical pumping magnetometers for applications in biomagnetism.

  3. Dynamical quenching of tunneling in molecular magnets

    Energy Technology Data Exchange (ETDEWEB)

    José Santander, María, E-mail: maria.jose.noemi@gmail.com [Recursos Educativos Quántica, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Roldán-Molina, A. [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Curauma, Valparaíso (Chile); Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso (Chile)

    2015-12-15

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation. - Highlights: • Single molecular magnets under rapidly oscillating magnetic fields is studied. • It is shown that this system displays the quenching of tunneling processes. • Our findings provide a control of quantum molecular magnets via terahertz radiation.

  4. Magnetic Field Control of Combustion Dynamics

    Science.gov (United States)

    Barmina, I.; Valdmanis, R.; Zake, M.; Kalis, H.; Marinaki, M.; Strautins, U.

    2016-08-01

    Experimental studies and mathematical modelling of the effects of magnetic field on combustion dynamics at thermo-chemical conversion of biomass are carried out with the aim of providing control of the processes developing in the reaction zone of swirling flame. The joint research of the magnetic field effect on the combustion dynamics includes the estimation of this effect on the formation of the swirling flame dynamics, flame temperature and composition, providing analysis of the magnetic field effects on the flame characteristics. The results of experiments have shown that the magnetic field exerts the influence on the flow velocity components by enhancing a swirl motion in the flame reaction zone with swirl-enhanced mixing of the axial flow of volatiles with cold air swirl, by cooling the flame reaction zone and by limiting the thermo-chemical conversion of volatiles. Mathematical modelling of magnetic field effect on the formation of the flame dynamics confirms that the electromagnetic force, which is induced by the electric current surrounding the flame, leads to field-enhanced increase of flow vorticity by enhancing mixing of the reactants. The magnetic field effect on the flame temperature and rate of reactions leads to conclusion that field-enhanced increase of the flow vorticity results in flame cooling by limiting the chemical conversion of the reactants.

  5. Spin Dynamics in Confined Magnetic Structures III

    CERN Document Server

    Hillebrands, Burkard

    2006-01-01

    This third volume of Spin Dynamics in Confined Magnetic Structures addresses central aspects of spin-dynamic phenomena, including recent new developments, on a tutorial level. Researchers will find a comprehensive compilation of the current work in the field. Introductory chapters help newcomers to understand the basic concepts. The more advanced chapters give the current state of the art of spin dynamic issues ranging from the femtosecond to the microsecond regime. This volume concentrates on new experimental techniques such as ferromagnetic-resonance-force microscopy and two-photon photoemission, as well as on aspects of precessional switching, spin-wave excitation, vortex dynamics, spin relaxation, domain-wall dynamics in nanowires and their applications to magnetic logic devices. An important chapter is devoted to the presently very hot subject of the spin-transfer torque, combining the physics of electronic transport and micromagnetics. The comprehensive presentation of these developments makes this volu...

  6. Magnetic Resonance Spectroscopic Imaging (MRSI Study of Breast Cancer

    Directory of Open Access Journals (Sweden)

    K. B. Ashok

    2011-05-01

    Full Text Available Background: Breast cancer is the fifth most common cause of cancer death worldwide and most serious form of neoplastic diseases in both developed and developing countries. Mammography and ultrasound are the most often used screening methods in breast cancer. Magnetic Resonance Imaging (MRI uses the protons in water and fat to create the image of breast cancer. But recent studies says neoplastic breast lesions contains elevated choline concentration (tCho and altered mean apparent diffusion coefficient (ADC which can be used as good biomarkers to evaluate the cancer stages even follow up the Neoadjuvent Chemotherapy (NACT.Aim & Objectives:1. To evaluate the relation of age, tCho concentration and mean ADC with breast cancer.2. To estimate the correlation between the factors.3. To calculate the main difference between breast cancer patient before and after menopause.Methods/Study Design: This was a cross sectional, observational study done on 14 randomly selected diagnosed stage I breast cancer patients newly registered in surgery department of All India Institute of Medical Sciences, New Delhi, India during 3 months study period. Intentionally 7 of them were selected to be postmenopausal and rest 7 premenopausal. Patients with claustrophobia, serious illness, pacemaker or associated diseases were excluded. Volunteers were selected by lottery method after confirmation of absence of the exclusion criteria in them. All the breast MRS images were taken only after signing the consent form of being a volunteer for the study with breast coil. All the spectroscopic images were analyzed with computer technologies and SPPS software with the help of non-parametric statistical tests.Results/Findings: Mean age of patients were 44.85±6.97 where in premenopausal and postmenopausal women it was 40.14±4.59 and 49.57±5.26 respectively. tCho concentration was high in postmenopausal women (4.85±2.64 mmol/kg vs 3.72±1.64 where unlike to them premenopausal women

  7. A functional calculus for the magnetization dynamics

    CERN Document Server

    Tranchida, Julien; Nicolis, Stam

    2016-01-01

    A functional calculus approach is applied to the derivation of evolution equations for the moments of the magnetization dynamics of systems subject to stochastic fields. It allows us to derive a general framework for obtaining the master equation for the stochastic magnetization dynamics, that is applied to both, Markovian and non-Markovian dynamics. The formalism is applied for studying different kinds of interactions, that are of practical relevance and hierarchies of evolution equations for the moments of the distribution of the magnetization are obtained. In each case, assumptions are spelled out, in order to close the hierarchies. These closure assumptions are tested by extensive numerical studies, that probe the validity of Gaussian or non--Gaussian closure Ans\\"atze.

  8. Diffusion weighted magnetic resonance imaging of the breast: protocol optimization, interpretation, and clinical applications.

    Science.gov (United States)

    Partridge, Savannah C; McDonald, Elizabeth S

    2013-08-01

    Diffusion-weighted magnetic resonance (MR) imaging (DWI) has shown promise for improving the positive predictive value of breast MR imaging for detection of breast cancer, evaluating tumor response to neoadjuvant chemotherapy, and as a noncontrast alternative to MR imaging in screening for breast cancer. However, data quality varies widely. Before implementing DWI into clinical practice, one must understand the pertinent technical considerations and current evidence regarding clinical applications of breast DWI. This article provides an overview of basic principles of DWI, optimization of breast DWI protocols, imaging features of benign and malignant breast lesions, promising clinical applications, and potential future directions.

  9. Magnetism From Fundamentals to Nanoscale Dynamics

    CERN Document Server

    Stöhr, Joachim

    2006-01-01

    The present text book gives an comprehensive account of magnetism, spanning the historical development, the physical foundations and the continuing research underlying the field, one of the oldest yet still vibrant field of physics. It covers both the classical and quantum mechanical aspects of magnetism and novel experimental techniques. Perhaps uniquely, it also discusses spin transport and magnetization dynamics phenomena associated with atomically and spin engineered nano-structures against the backdrop of spintronics and magnetic storage and memory applications. Despite the existence of various books on the topic, a fresh text book that reviews the fundamental physical concepts and uses them in a coherent fashion to explain some of the forefront problems and applications today was thought useful by the authors and their colleagues. Magnetism is written for students on the late undergraduate and the graduate levels and should also serve as a state-of-the-art reference for scientists in academia and resear...

  10. Dynamic interaction between rotor and axially-magnetized passive magnetic bearing considering magnetic eccentricity

    DEFF Research Database (Denmark)

    Enemark, Søren; Santos, Ilmar

    2014-01-01

    Passive magnetic bearings are known due to the excellent characteristics in terms of friction and no requirement of additional energy sources to work. However, passive magnetic bearings do not provide damping, are not stable and, depending on their design, may also introduce magnetic eccentricity....... Such magnetic eccentricities are generated by discrepancies in magnet fabrication. In this framework the main focus of the work is the theoretical as well as experimental investigation of the nonlinear dynamics of a rotor-bearing system with strong emphasis on the magnetic eccentricities and non......-linear stiffness. In this investigation passive magnetic bearings using axially- aligned neodymium cylinder magnets are investigated. The cylinder magnets are axially magnetised for rotor as well as bearings. Compared to bearings with radial magnetisation, the magnetic stiffness of axially-aligned bearings...

  11. Subtraction and dynamic MR images of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Yoshitaka; Aoki, Manabu; Harada, Junta (Jikei Univ., Tokyo (Japan). School of Medicine)

    1993-04-01

    The purpose of this study was to evaluate the diagnostic effectiveness of subtraction and dynamic MR imaging in patients with breast masses. In 23 breast cancers and six fibroadenomas, spin echo T1 images were obtained at 0.2 Tesla before and every minute after intravenous injection of Gd-DTPA (0.1 or 0.2 mmol/kg). Subtraction images were obtained sequentially on the CRT monitor. All breast masses were enhanced after gadolinium and stood out as bright lesions on subtraction images. The tumor margin and its extension were more precisely evaluated on subtraction MR images than on conventional postcontrast MR images. Breast cancer showed a characteristic time-intensity curve with an early peak, in contrast to fibroadenoma, which showed a gradual increase in signal intensity. Subtraction MR imaging is a simple method for the evaluation of breast masses, and further, the time-intensity curve obtained by dynamic study is helpful in the differential diagnosis of lesions. (author).

  12. Study of Magnetic Domain Dynamics Using Nonlinear Magnetic Responses: Magnetic Diagnostics of the Itinerant Magnet MnP

    Science.gov (United States)

    Mito, Masaki; Matsui, Hideaki; Tsuruta, Kazuki; Deguchi, Hiroyuki; Kishine, Jun-ichiro; Inoue, Katsuya; Kousaka, Yusuke; Yano, Shin-ichiro; Nakao, Yuya; Akimitsu, Jun

    2015-10-01

    The nonlinear and linear magnetic responses to an ac magnetic field H are useful for the study of the magnetic dynamics of both magnetic domains and their constituent spins. In particular, the third-harmonic magnetic response M3ω reflects the dynamics of magnetic domains. Furthermore, by considering the ac magnetic response as a function of H, we can evaluate the degree of magnetic nonlinearity, which is closely related to M3ω. In this study, a series of approaches was used to examine the itinerant magnet MnP, in which both ferromagnetic and helical phases are present. On the basis of this investigation, we systematize the diagnostic approach to evaluating nonlinearity in magnetic responses.

  13. Large-scale dynamics of magnetic helicity

    Science.gov (United States)

    Linkmann, Moritz; Dallas, Vassilios

    2016-11-01

    In this paper we investigate the dynamics of magnetic helicity in magnetohydrodynamic (MHD) turbulent flows focusing at scales larger than the forcing scale. Our results show a nonlocal inverse cascade of magnetic helicity, which occurs directly from the forcing scale into the largest scales of the magnetic field. We also observe that no magnetic helicity and no energy is transferred to an intermediate range of scales sufficiently smaller than the container size and larger than the forcing scale. Thus, the statistical properties of this range of scales, which increases with scale separation, is shown to be described to a large extent by the zero flux solutions of the absolute statistical equilibrium theory exhibited by the truncated ideal MHD equations.

  14. The Origin and Dynamics of Solar Magnetism

    CERN Document Server

    Thompson, M. J; Culhane, J. L; Nordlund, Å; Solanki, S. K; Zahn, J.-P

    2009-01-01

    The articles collected in this volume present all aspects of solar magnetism: from its origin in the solar dynamo to its evolution and dynamics that create the variability of solar phenomena, its well-known 11-year activity cycle that leads to the ever-changing pattern of sunspots and active regions on the Sun. Several contributions deal with the solar dynamo, the driver of many solar phenomena. Other contributions treat the transport and emergence of the magnetic flux through the outer layers of the Sun. The coupling of magnetic fields from the surface to the solar corona and beyond is also described, together with current studies on the predictability of solar activity. This book is aimed at researchers and graduate students working in solar physics and space science. It provides a full review of our current understanding of solar magnetism by the foremost experts in the field.

  15. Multimodal breast cancer imaging using coregistered dynamic diffuse optical tomography and digital breast tomosynthesis

    Science.gov (United States)

    Zimmermann, Bernhard B.; Deng, Bin; Singh, Bhawana; Martino, Mark; Selb, Juliette; Fang, Qianqian; Sajjadi, Amir Y.; Cormier, Jayne; Moore, Richard H.; Kopans, Daniel B.; Boas, David A.; Saksena, Mansi A.; Carp, Stefan A.

    2017-04-01

    Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breast cancer diagnosis and neoadjuvant chemotherapy monitoring. In particular, the multimodal approach of combining DOT with x-ray digital breast tomosynthesis (DBT) is especially synergistic as DBT prior information can be used to enhance the DOT reconstruction. DOT, in turn, provides a functional information overlay onto the mammographic images, increasing sensitivity and specificity to cancer pathology. We describe a dynamic DOT apparatus designed for tight integration with commercial DBT scanners and providing a fast (up to 1 Hz) image acquisition rate to enable tracking hemodynamic changes induced by the mammographic breast compression. The system integrates 96 continuous-wave and 24 frequency-domain source locations as well as 32 continuous wave and 20 frequency-domain detection locations into low-profile plastic plates that can easily mate to the DBT compression paddle and x-ray detector cover, respectively. We demonstrate system performance using static and dynamic tissue-like phantoms as well as in vivo images acquired from the pool of patients recalled for breast biopsies at the Massachusetts General Hospital Breast Imaging Division.

  16. Molecular dynamics simulations of magnetized dusty plasmas

    Science.gov (United States)

    Piel, Alexander; Reichstein, Torben; Wilms, Jochen

    2012-10-01

    The combination of the electric field that confines a dust cloud with a static magnetic field generally leads to a rotation of the dust cloud. In weak magnetic fields, the Hall component of the ion flow exerts a drag force that sets the dust in rotation. We have performed detailed molecular-dynamics simulations of the dynamics of torus-shaped dust clouds in anodic plasmas. The stationary flow [1] is characterized by a shell structure in the laminar dust flow and by the spontaneous formation of a shear-flow around a stationary vortex. Here we present new results on dynamic phenomena, among them fluctuations due to a Kelvin-Helmholtz instability in the shear-flow. The simulations are compared with experimental results. [4pt] [1] T. Reichstein, A. Piel, Phys. Plasmas 18, 083705 (2011)

  17. Multiscale Dynamics of Solar Magnetic Structures

    Science.gov (United States)

    Uritsky, Vadim M.; Davila, Joseph M.

    2012-01-01

    Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries.We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

  18. Dynamic Characterization of Thin Film Magnetic Materials

    Science.gov (United States)

    Gu, Wei

    A broadband dynamic method for characterizing thin film magnetic material is presented. The method is designed to extract the permeability and linewidth of thin magnetic films from measuring the reflection coefficient (S11) of a house-made and short-circuited strip line testing fixture with or without samples loaded. An adaptive de-embedding method is applied to remove the parasitic noise of the housing. The measurements were carried out with frequency up to 10GHz and biasing magnetic fields up to 600 Gauss. Particular measurement setup and 3-step experimental procedures are described in detail. The complex permeability of a 330nm thick continuous FeGaB, 435nm thick laminated FeGaB film and a 100nm thick NiFe film will be induced dynamically in frequency-biasing magnetic field spectra and compared with a theoretical model based on Landau-Lifshitz-Gilbert (LLG) equations and eddy current theories. The ferromagnetic resonance (FMR) phenomenon can be observed among these three magnetic materials investigated in this thesis.

  19. Clinical Application of Magnetic Resonance Imaging in Management of Breast Cancer Patients Receiving Neoadjuvant Chemotherapy

    Directory of Open Access Journals (Sweden)

    Jeon-Hor Chen

    2013-01-01

    Full Text Available Neoadjuvant chemotherapy (NAC, also termed primary, induction, or preoperative chemotherapy, is traditionally used to downstage inoperable breast cancer. In recent years it has been increasingly used for patients who have operable cancers in order to facilitate breast-conserving surgery, achieve better cosmetic outcome, and improve prognosis by reaching pathologic complete response (pCR. Many studies have demonstrated that magnetic resonance imaging (MRI can assess residual tumor size after NAC, and that provides critical information for planning of the optimal surgery. NAC also allows for timely adjustment of administered drugs based on response, so ineffective regimens could be terminated early to spare patients from unnecessary toxicity while allowing other effective regimens to work sooner. This review article summarizes the clinical application of MRI during NAC. The use of different MR imaging methods, including dynamic contrast-enhanced MRI, proton MR spectroscopy, and diffusion-weighted MRI, to monitor and evaluate the NAC response, as well as how changes of parameters measured at an early time after initiation of a drug regimen can predict final treatment outcome, are reviewed. MRI has been proven a valuable tool and will continue to provide important information facilitating individualized image-guided treatment and personalized management for breast cancer patients undergoing NAC.

  20. Phosphorus-31 metabolism of human breast - an in vivo magnetic resonance spectroscopic study at 1. 5 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Twelves, C.J.; Lowry, M.; Dobbs, N.A.; Richards, M.A. (Imperial Cancer Research Fund, London (United Kingdom). Clinical Oncology Unit); Porter, D.A.; Graves, P.E.; Smith, M.A. (Guy' s Hospital, London (United Kingdom))

    1994-01-01

    The authors studied the metabolisms of compounds containing [sup 31]P in normal breast using magnetic resonance spectroscopy (MRS). Spectra were acquired from non-lactating pre-menopausal breast with and without the oral contraceptive pill (n = 14 women), lactating breast (n = 8) and post-menopausal breast (n 8). (author).

  1. Dynamic Assembly of Magnetic Colloidal Vortices

    Energy Technology Data Exchange (ETDEWEB)

    Mohorič, Tomaž; Kokot, Gašper; Osterman, Natan; Snezhko, Alexey; Vilfan, Andrej; Babič, Dušan; Dobnikar, Jure

    2016-04-29

    Magnetic colloids in external time-dependent fields are subject to complex induced many-body interactions governing their self-assembly into a variety of equilibrium and out-of-equilibrium structures such as chains, networks, suspended membranes, and colloidal foams. Here, we report experiments, simulations, and theory probing the dynamic assembly of superparamagnetic colloids in precessing external magnetic fields. Within a range of field frequencies, we observe dynamic large-scale structures such as ordered phases composed of precessing chains, ribbons, and rotating fluidic vortices. We show that the structure formation is inherently coupled to the buildup of torque, which originates from internal relaxation of induced dipoles and from transient correlations among the particles as a result of short-lived chain formation. We discuss in detail the physical properties of the vortex phase and demonstrate its potential in particle-coating applications.

  2. Multiscale Model Approach for Magnetization Dynamics Simulations

    CERN Document Server

    De Lucia, Andrea; Tretiakov, Oleg A; Kläui, Mathias

    2016-01-01

    Simulations of magnetization dynamics in a multiscale environment enable rapid evaluation of the Landau-Lifshitz-Gilbert equation in a mesoscopic sample with nanoscopic accuracy in areas where such accuracy is required. We have developed a multiscale magnetization dynamics simulation approach that can be applied to large systems with spin structures that vary locally on small length scales. To implement this, the conventional micromagnetic simulation framework has been expanded to include a multiscale solving routine. The software selectively simulates different regions of a ferromagnetic sample according to the spin structures located within in order to employ a suitable discretization and use either a micromagnetic or an atomistic model. To demonstrate the validity of the multiscale approach, we simulate the spin wave transmission across the regions simulated with the two different models and different discretizations. We find that the interface between the regions is fully transparent for spin waves with f...

  3. Nambu mechanics for stochastic magnetization dynamics

    CERN Document Server

    Thibaudeau, Pascal; Nicolis, Stam

    2016-01-01

    The Landau-Lifshitz-Gilbert (LLG) equation describes the dynamics of a damped magnetization vector that can be understood as a generalization of Larmor spin precession. The LLG equation cannot be deduced from the Hamiltonian framework, by introducing a coupling to a usual bath, but requires the introduction of additional constraints. It is shown that these constraints can be formulated elegantly and consistently in the framework of dissipative Nambu mechanics. This has many consequences for both the variational principle and for topological aspects of hidden symmetries that control conserved quantities. We particularly study how the damping terms of dissipative Nambu mechanics affect the consistent interaction of magnetic systems with stochastic reservoirs and derive a master equation for the magnetization. The proposals are supported by numerical studies using symplectic integrators that preserve the topological structure of Nambu equations. These results are compared to computations performed by direct samp...

  4. 年轻女性乳腺癌保乳术前动态增强磁共振成像检查的必要性%The essentiality of dynamic contrast enhanced magnetic resonance imaging examination before breast-conserving surgery in breast cancer patients with young women

    Institute of Scientific and Technical Information of China (English)

    高明; 钮亚珍; 邢亮; 冯娜

    2013-01-01

    Objective To explore the essentiality of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) examination before breast-conserving surgery (BCS) in breast cancer patients with young women.Methods The data of DCE-MRI and mammography X-ray in 30 breast cancer patients with young women (< 40 years old) who received surgery with pathology-proven were retrospectively analyzed.The detection rate of breast lesion,number,size,extent of invasive and lymph node metastasis of preoperative were observed.The DCE-MRI was assessed accuracy of BCS in accordance with indications for BCS and histopathology results.Results The breast cancer detection rate of DCE-MRI was significantly higher than mammography X-ray [100.00%(30/30) vs.73.33%(22/30),P =0.002].The maximum tumor diameter of DCE-MRI was (3.55 ± 1.50) cm,mammography X-ray was (3.38 ± 1.70) cm,postoperative pathology was (3.51 ± 1.20) cm,and DCE-MRI was closer to postoperative pathology than mammography X-ray.The discovery of additional lesions of DCE-MRI was more than mammography X-ray (P < 0.05).The surrounding tissue invasion of DCE-MRI was detected in 22 cases,mammography X-ray was in 9 cases,postoperative pathology was in 19 cases,there was no significant difference between DCE-MRI and postoperative pathology (P =0.598),there was significant difference between mammography X-ray and postoperative pathology (P =0.010).The number of axillary fossa lymph node metastasis of DCE-MRI was in 127,mammography X-ray was in 48,compared with postoperative pathology (91),there was significant difference (P =0.026,0.034).The detection of microcalcification of mammography X-ray was better than DCE-MRI (7 cases vs.0 case,P =0.001).The number of BCS of postoperative pathology was in 12 cases,DCE-MRI was in 11 cases,mammography X-ray was in 8 cases,DCE-MRI was higher than mammography X-ray,but there was no significant difference (P=0.132).Conclusion DCE-MRI provides comprehensive and accurate information for breast

  5. Dynamical magnetic effects in photoexcited ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chovan, J. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P. O. Box 1527, 711 10 Heraklion (Greece); Kavousanaki, E.G. [Department of Physics, University of Crete, P. O. Box 2208, 710 03 Heraklion (Greece); Perakis, I.E. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, P. O. Box 1527, 711 10 Heraklion (Greece); Department of Physics, University of Crete, P. O. Box 2208, 710 03 Heraklion (Greece)

    2006-08-15

    We develop a theory of photoinduced dynamical magnetic effects in III-Mn-V ferromagnetic semiconductors valid in presence of strong carrier spin relaxation and dephasing. We treat relaxation by using the Lindblad semigroup method and calculate the nonlinear response numerically. We predict Mn-spin relaxation and precession towards the direction determined by nonlinear optical polarization. These effects occur during the pulse. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Use of magnetic resonance imaging in detection of breast cancer recurrence: a systematic review.

    LENUS (Irish Health Repository)

    Quinn, Edel Marie

    2012-09-01

    Diagnosis of breast cancer recurrence can be difficult as a result of the presence of scar tissue in the breast. Magnetic resonance imaging (MRI) may be superior to traditional imaging in diagnosis of recurrence because of its ability to differentiate malignancy from scarring. Current guidelines on investigation of suspected breast cancer recurrence recommend MRI when other investigations have equivocal findings. We performed the first systematic review on this topic.

  7. Intraindividual, randomized comparison of the macrocyclic contrast agents gadobutrol and gadoterate meglumine in breast magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fallenberg, Eva M.; Renz, Diane M.; Hamm, Bernd [Charite - Universitaetsmedizin Berlin, Campus Virchow-Klinikum, Department of Radiology, Berlin (Germany); Karle, Bettina [Clinic of Radiation Therapy, Helios Clinics, Berlin (Germany); Schwenke, Carsten [SCOSSIS Statistical Consulting, Berlin (Germany); Ingod-Heppner, Barbara [Charite Universitaetsmedizin, Campus Charite Mitte, Institute of Pathology, Berlin (Germany); Reles, Angela [Charite Universitaetsmedizin, Charite-Partner-Practice, Interdisciplinary Breast Center, Berlin (Germany); Engelken, Florian J. [Charite - Universitaetsmedizin Berlin, Charite Campus Mitte, Department of Radiology, Berlin (Germany); Huppertz, Alexander; Taupitz, Matthias [Charite - Universitaetsmedizin Berlin, Campus Benjamin Franklin, Department of Radiology, Berlin (Germany)

    2014-09-25

    To compare intraindividually two macrocyclic contrast agents - gadobutrol and gadoterate meglumine (Gd-DOTA) - for dynamic and quantitative assessment of relative enhancement (RE) in benign and malignant breast lesions. This was an ethically approved, prospective, single-centre, randomized, crossover study in 52 women with suspected breast lesions referred for magnetic resonance imaging (MRI). Each patient underwent one examination with gadobutrol and one with Gd-DOTA (0.1 mmol/kg BW) on a 1.5 T system 1 - 7 days apart. Dynamic, T1-weighted, 3D gradient echo sequences were acquired under identical conditions. Quantitative evaluation with at least three regions of interest (ROI) per lesion was performed. Primary endpoint was RE during the initial postcontrast phase after the first and second dynamic acquisition, and peak RE. All lesions were histologically proven; differences between the examinations were evaluated. Forty-five patients with a total of 11 benign and 34 malignant lesions were assessed. Mean RE was significantly higher for gadobutrol than Gd-DOTA (p < 0.0001). Gadobutrol showed significantly less washout (64.4 %) than Gd-DOTA (75.4 %) in malignant lesions (p = 0.048) Gadobutrol has higher RE values compared with Gd-DOTA, whereas Gd-DOTA shows more marked washout in malignant lesions. This might improve the detection of breast lesions and influence the specificity of breast MRI-imaging. (orig.)

  8. Correlation between dynamic contrast-enhanced MRI and histopathology in the measurement of tumor and breast volume and their ratio in breast cancer patients: a prospective study

    Institute of Scientific and Technical Information of China (English)

    LIU Qian; YE Jing-ming; XU Ling; DUAN Xue-ning; ZHAO Jian-xin; LIU Yin-hua

    2012-01-01

    Background Earlier studies have examined the association between the diameter of primary tumors measured by magnetic resonance imaging (MRI) and histopathology in breast cancer patients.However,the diameter does not completely describe the dimensions of the breast tumor or its volumetric proportion relative to the whole breast.The association between breast tumor volume/breast volume ratios measured by these two techniques has not been reported.Methods Seventy-three patients were recruited from female patients with primary breast tumors admitted to our center between January and December 2010.They were divided into two groups.Group A (n=46) underwent modified radical mastectomy (MRM),and Group B (n=27) underwent preoperative neoadjuvant chemotherapy before MRM.They were examined by dynamic-contrast enhanced MRI (DCE-MRI) to measure breast volumes (BVs),tumor volumes (TVs),and tumor volume/breast volume ratios (TV/BV).These measurements were compared with histopathology results after MRM,and the associations between MRI and pathology were analyzed by linear regression and Bland-Altman analysis.Results For Group A,the correlation coefficients for BVs,TVs,and TV/BV ratios measured by the two techniques were 0.938,0.921,and 0.897 (all P <0.001),respectively.For Group B,the correlation coefficients for BVs,TVs,and TV/BV ratios were 0.936,0.902,and 0.869 (all P<0.01),respectively.The results suggest statistically significant correlations between these parameters measured by the two techniques for both groups.Conclusion For these patients,BVs,TVs,and TV/BV ratios measured by DCE-MRI significantly correlated with those determined by histopathology.

  9. Domain wall dynamics of magnetically bistable microwires

    Directory of Open Access Journals (Sweden)

    Ipatov M.

    2012-06-01

    Full Text Available We studied domain wall propagation of magnetically-bistable Fe- Co-rich microwires paying attention on effect of applied and internal stresses. We measured hysteresis loops and domain wall propagation in various magnetic Fe- Co-rich amorphous microwires with metallic nucleus diameters (from 12 □m till 22 □m using Sixtus Tonks-like experiments. Application of tensile stresses results in decreasing of domain wall velocity. We discussed magnetoelastic contribution in dynamics of domain wall propagation. We observed, that microwires with different geometries exhibit v(H dependences with different slopes. Application of stresses resulted in decrease of DW velocity, v, and DW mobility S. Quite fast DW propagation (v till 2500 m/s at H about 30 A/m has been observed in low magnetostrictive magnetically bistable Co56Fe8Ni10Si110B16 microwires. Consequently, we can assume that generally magnetoelastic energy affects DW dynamics: decreasing magnetoelastic energy, Kme, DW velocity increases.

  10. Coupled spin, elastic and charge dynamics in magnetic nanostructures

    NARCIS (Netherlands)

    Kamra, A.

    2015-01-01

    In this Thesis, I address the interaction of magnetic degrees of freedom with charge current and elastic dynamics in hybrid systems composed of magnetic and non-magnetic materials. The objective, invariably, is to control and study spin dynamics using charge and elastic degrees of freedom. In certai

  11. Contrast-enhanced breast MR imaging of claustrophobic or oversized patients using an open low-field magnet.

    Science.gov (United States)

    Calabrese, M; Brizzi, D; Carbonaro, L; Chiaramondia, M; Kirchin, M A; Sardanelli, F

    2009-03-01

    A number of women who should undergo magnetic resonance (MR) imaging of the breast cannot use this diagnostic tool due to claustrophobia or excessive body size for the restricted confines of standard closed MR systems. Our aim was to evaluate the performance of open low-field magnet breast MR imaging in such patients using a high-relaxivity contrast agent. Of 397 consecutive patients undergoing breast MR imaging, 379 (95.5%) were studied at 1.5 T. Due to claustrophobia (n=15) or large body size (n=3), 18 patients (4.5%) were studied on a 0.2-T open magnet using a body coil. A 3D dynamic T1-weighted gradient-echo 94-s sequence was acquired with intravenous injection of gadobenate dimeglumine (0.1 mmol/kg). The standard of reference was pathological examination for 16 lesions classified with a maximal Breast Imaging Reporting and Data System (BI-RADS) score from 3 to 5, fine-needle aspiration cytology and >or=2-year follow-up for two lesions classified as BI-RADS 3, and >or=2-years follow-up for five lesions classified as BI-RADS 2. Diagnostic MR image quality was achieved for 20/23 lesions in 15/18 patients. Three lesions (two invasive cancers and a cyst) were not assessed due to patient movement and considered as two false negatives and one false positive. Thus, an 86% sensitivity [13/15; 95% confidence interval (CI): 70%-100%], an 87% specificity (7/8; 95% CI: 65%-100%) and an 87% accuracy (20/23; 95% CI: 73%-100%) were obtained. The intraclass correlation coefficient between MR and pathologic lesion size was 0.845. In claustrophobic or oversized patients, open low-field breast MR with gadobenate dimeglumine yields good diagnostic performance.

  12. Aptamer-conjugated Magnetic Nanoparticles as Targeted Magnetic Resonance Imaging Contrast Agent for Breast Cancer

    Science.gov (United States)

    Keshtkar, Mohammad; Shahbazi-Gahrouei, Daryoush; Khoshfetrat, Seyyed Mehdi; Mehrgardi, Masoud A.; Aghaei, Mahmoud

    2016-01-01

    Early detection of breast cancer is the most effective way to improve the survival rate in women. Magnetic resonance imaging (MRI) offers high spatial resolution and good anatomic details, and its lower sensitivity can be improved by using targeted molecular imaging. In this study, AS1411 aptamer was conjugated to Fe3O4@Au nanoparticles for specific targeting of mouse mammary carcinoma (4T1) cells that overexpress nucleolin. In vitro cytotoxicity of aptamer-conjugated nanoparticles was assessed on 4T1 and HFFF-PI6 (control) cells. The ability of the synthesized nanoprobe to target specifically the nucleolin overexpressed cells was assessed with the MRI technique. Results show that the synthesized nanoprobe produced strongly darkened T2-weighted magnetic resonance (MR) images with 4T1 cells, whereas the MR images of HFFF-PI6 cells incubated with the nanoprobe are brighter, showing small changes compared to water. The results demonstrate that in a Fe concentration of 45 μg/mL, the nanoprobe reduced by 90% MR image intensity in 4T1 cells compared with the 27% reduction in HFFF-PI6 cells. Analysis of MR signal intensity showed statistically significant signal intensity difference between 4T1 and HFFF-PI6 cells treated with the nanoprobe. MRI experiments demonstrate the high potential of the synthesized nanoprobe as a specific MRI contrast agent for detection of nucleolin-expressing breast cancer cells. PMID:28028501

  13. Magnetization dynamics of imprinted non-collinear spin textures

    Energy Technology Data Exchange (ETDEWEB)

    Streubel, Robert, E-mail: r.streubel@ifw-dresden.de; Kopte, Martin; Makarov, Denys, E-mail: d.makarov@ifw-dresden.de [Institute for Integrative Nanosciences, IFW Dresden, 01069 Dresden (Germany); Fischer, Peter [Center for X-Ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Physics Department, UC Santa Cruz, Santa Cruz, California 95064 (United States); Schmidt, Oliver G. [Institute for Integrative Nanosciences, IFW Dresden, 01069 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107 Chemnitz (Germany)

    2015-09-14

    We study the magnetization dynamics of non-collinear spin textures realized via imprint of the magnetic vortex state in soft permalloy into magnetically hard out-of-plane magnetized Co/Pd nanopatterned heterostructures. Tuning the interlayer exchange coupling between soft- and hard-magnetic subsystems provides means to tailor the magnetic state in the Co/Pd stack from being vortex- to donut-like with different core sizes. While the imprinted vortex spin texture leads to the dynamics similar to the one observed for vortices in permalloy disks, the donut-like state causes the appearance of two gyrofrequencies characteristic of the early and later stages of the magnetization dynamics. The dynamics are described using the Thiele equation supported by the full scale micromagnetic simulations by taking into account an enlarged core size of the donut states compared to magnetic vortices.

  14. Frequency and Clinical Significance of Extramammary Findings on Breast Magnetic Resonance Imaging.

    Science.gov (United States)

    Phadke, Sneha; Thomas, Alexandra; Yang, Limin; Moore, Catherine; Xia, Chang; Schroeder, Mary C

    2016-10-01

    Use of breast magnetic resonance imaging (MRI) for screening and local staging of breast cancer has increased. With this, questions have emerged regarding the management and effect of extramammary findings (EMFs) reported on breast MRI. Breast MRI studies performed between January 1, 2007 and December 31, 2012 at the University of Iowa were analyzed. Data were collected regarding number and location of EMFs, characteristics of the patients who had a breast MRI, and time to first treatment among the patients who had a breast MRI for stage I-III breast cancer. During the study period, 1305 breast MRIs were obtained in 772 women. An EMF was found in 140 studies (10.7%) and 113 women (14.6%). EMFs were more likely in MRIs of older patients (50 vs. 54 years, P = .004) and postmenopausal women (P = .001). Anatomically, most EMFs were seen in the liver (89 of 140) or bone (21 of 140). Eight women (0.6%) had an EMF on breast MRI that led to upstaging to stage IV breast cancer. For patients with stage I-III breast cancer, the finding of an EMF on breast MRI did not affect time to initial cancer treatment (13 vs. 14 days; P = .586). EMFs on breast MRI are seen with some frequency and occur more commonly in older, postmenopausal women. In our study, most EMFs were benign and did not affect patient outcome with regard to upstaging to stage IV disease or time to cancer treatment. A very small portion of studies revealed subclinical advanced breast cancer. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Proton and phosphorus magnetic resonance spectroscopy of the healthy human breast at 7 T

    NARCIS (Netherlands)

    van der Kemp, Wybe J M; Stehouwer, Bertine L; Boer, Vincent O; Luijten, Peter R; Klomp, DWJ; Wijnen, Jannie P

    In vivo water- and fat-suppressed (1) H magnetic resonance spectroscopy (MRS) and (31) P magnetic resonance adiabatic multi-echo spectroscopic imaging were performed at 7 T in duplicate in healthy fibroglandular breast tissue of a group of eight volunteers. The transverse relaxation times of (31) P

  16. Dynamic Elasticity of a Magnetic Fluid Column in a Strong Magnetic Field

    Science.gov (United States)

    Polunin, V. M.; Ryapolov, P. A.; Shel'deshova, E. V.; Kuz'ko, A. E.; Aref'ev, I. M.

    2017-07-01

    The elastomagnetic parameters of a magnetic fluid kept by magnetic levitation in a tube placed horizontally in a strong magnetic field are measured, including the oscillation frequency, the ponderomotive and dynamic elasticity coefficients, the magnetization curve, and the magnetic field strength and its gradient. Results of calculations for the model of ponderomotive elasticity for the examined sample of the magnetic fluid corrected for the resistance of the moving viscous fluid are in good agreement with the experimental magnetization curve. The described method is of interest for a study of magnetophoresis, nanoparticle aggregations, viscosity, and their time dependences in magnetic colloids.

  17. Glandular breast tissue volume by magnetic resonance imaging in 100 healthy peripubertal girls

    DEFF Research Database (Denmark)

    Fugl, Louise; Hagen, Casper P; Mieritz, Mikkel G

    2016-01-01

    BACKGROUND: Appearance of glandular breast tissue may be difficult to distinguish from fat tissue by palpation, especially in obese girls. To our knowledge, validation of the clinical assessment of pubertal breast stages by magnetic resonance imaging (MRI) has never been performed. Our objective....... METHODS: Glandular breast tissue volume quantified by MRI and breast stage evaluation was performed in 100 healthy peripubertal girls. Circulating levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), inhibin B, and estradiol were measured by immunoassays. Ovarian volume, uterine volume....... The best parameters to distinguish prepubertal girls from girls with breast development were: LH (area under the curve (AUC) by receiver operating characteristic analysis = 0.871), inhibin B (AUC = 0.847) and estradiol (AUC = 0.830). CONCLUSION: Clinical palpation reliably detects the presence of glandular...

  18. Image fusion for dynamic contrast enhanced magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Leach Martin O

    2004-10-01

    Full Text Available Abstract Background Multivariate imaging techniques such as dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI have been shown to provide valuable information for medical diagnosis. Even though these techniques provide new information, integrating and evaluating the much wider range of information is a challenging task for the human observer. This task may be assisted with the use of image fusion algorithms. Methods In this paper, image fusion based on Kernel Principal Component Analysis (KPCA is proposed for the first time. It is demonstrated that a priori knowledge about the data domain can be easily incorporated into the parametrisation of the KPCA, leading to task-oriented visualisations of the multivariate data. The results of the fusion process are compared with those of the well-known and established standard linear Principal Component Analysis (PCA by means of temporal sequences of 3D MRI volumes from six patients who took part in a breast cancer screening study. Results The PCA and KPCA algorithms are able to integrate information from a sequence of MRI volumes into informative gray value or colour images. By incorporating a priori knowledge, the fusion process can be automated and optimised in order to visualise suspicious lesions with high contrast to normal tissue. Conclusion Our machine learning based image fusion approach maps the full signal space of a temporal DCE-MRI sequence to a single meaningful visualisation with good tissue/lesion contrast and thus supports the radiologist during manual image evaluation.

  19. REVIEW Magnetic resonance imaging of the breast: A clinical ...

    African Journals Online (AJOL)

    for breast cancer and its use after the diagnosis of breast cancer is discussed. The topic is ... decreased recurrence and, as a consequence, improved patient survival. Are patients benefitting or are they just ... lung metastasis. Two per cent had ...

  20. 高场磁共振三维动态增强结合扩散加权成像对乳腺良性和恶性病变的鉴别诊断%The distinguish diagnosis of benign and malignant breast diseases with three dimensional dynamic enhance-ment and DWI in high magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    李斯琴; 韩晓东; 张晖; 杜晓东; 吕云罡

    2014-01-01

    malignant breast diseases with three-dimensional (3D) dynamic enhancement and DWI in high magnetic resonance imaging. Methods Forty-six patients who were suffered breast diseases confirmed by pathology had been scanned with DWI and 3D dynamic enhancement in breast magnetic resonance imaging (MRI), and the ADC pictures respectively were drawn according to different b values of 800 and 1 000 s/mm2. Statistically assess the two kinds of breast diseases′sensitivity, specificity, positive predictive value, and negative predictive value by time-signal intensity curve. Results Among 46 cases, there were 28 patients of malignant breast diseases including 24 cases of infiltrating ductal carcinoma, 3 cases of medullary car-cinoma, and 1 case of lobular carcinoma; 18 cases of benign breast diseases (10 cases of fibroadenoma, 2 cases of atypical hyperplasia, 4 cases of cystic hyperplasia, 2 cases of abscess). When b value was 800 s/mm 2, benign, malig-nant and normal breast tissue′s ADC value were separately (1.54±0.28)×10-3 mm2/s ,(1.01±0.09)×10-3 mm2/s, and (1.49 ±0.06) ×10-3 mm2/s; when it was 1 000 s/mm2, their values were (1.45 ±0.28) ×10-3 mm2/s, (0.90 ±0.08) ×10-3 mm2/s, and(1.49±0.09)×10-3 mm2/s. There was significant statistical difference (P<0.05). The 95%of the reference in-terval in ADC values of malignant and normal breast tissues were(0.97-1.05)×10-3 mm2/s, (0.90-0.97)×10-3 mm2/s. In 28 malignant breast diseases, there were 18 cases of inflow type (64%), 9 cases of platform type(32%), and 1 case of outflow type (3.5%); yet in 18 benign diseases, there were 13 cases of inflow type (72%), 3 cases of platform type (17%), and 1 case of outflow type (6%). The sensitivity, specificity, positive predictive value, and negative predictive value by time-signal intensity curve were 96%(27/28), 83%(15/18) respectively. Conclusion The application of combining 3D dynamic enhancement with DWI sequences could improve distinguish diagnosis of benign and malig-nant breast

  1. Radial scars of the breast: contrast-enhanced magnetic resonance mammography appearance.

    Science.gov (United States)

    Pediconi, Federica; Occhiato, Rossella; Venditti, Fiammetta; Fraioli, Francesco; Napoli, Alessandro; Votta, Vito; Laghi, Andrea; Catalano, Carlo; Passariello, R

    2005-01-01

    The purpose of this study was to evaluate the appearance of contrast-enhanced magnetic resonance mammography (CE-MRM) in patients with suspected radial scar on mammography. Thirty women with radial opacities or black star findings at mammography, preoperatively underwent CE-MRM. Examinations were performed with a 1.5 T magnet with a bilateral surface coil using a FS T2-weighted turbo spin echo (TSE) and three-dimensional (3D) dynamic T1-weighted fast low-angle shot (FLASH) sequences. Criteria for lesion evaluation included morphologic patterns and signal intensity curves. Mammography and CE-MRM findings were compared with pathologic findings. CE-MRM suggested the presence of radial scar in 18 of 30 cases and the presence of malignancy in 11 of 30 cases; 1 lesion was classified as borderline. At surgery 22 radial scars (including 4 with associated ductal carcinoma in situ) and 8 carcinomas were detected. CE-MRM provided a specificity of 89%, sensitivity of 83%, and accuracy of 87%. Differently from breast cancer, radial scars are nonenhancing at CE-MRM. Nevertheless, the possibility of nonenhancing carcinomatous foci existing within radial scars implies that surgical excision should be performed in all cases.

  2. Thermally induced dynamics in ultrathin magnetic tunnel junctions

    NARCIS (Netherlands)

    Ogrodnik, P.; Bauer, G.E.W.; Xia, K.

    2013-01-01

    We consider the magnetization dynamics induced by thermally induced spin transfer torques in thin Fe|MgO|Fe tunnel junctions. The magnetization dynamics is described by the Landau-Lifshitz-Gilbert equation, including the thermal torques as computed from first principles. We show that the angular ske

  3. Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.

  4. Dynamics of magnetic nanoparticles in viscoelastic media

    Science.gov (United States)

    Remmer, Hilke; Roeben, Eric; Schmidt, Annette M.; Schilling, Meinhard; Ludwig, Frank

    2017-04-01

    We compare different models for the description of the complex susceptibility of magnetic nanoparticles in an aqueous gelatin solution representing a model system for a Voigt-Kelvin scheme. The analysis of susceptibility spectra with the numerical model by Raikher et al. [7] is compared with the analysis applying a phenomenological, modified Debye model. The fit of the models to the measured data allows one to extract the viscoelastic parameter dynamic viscosity η and shear modulus G. The experimental data were recorded on single-core thermally blocked CoFe2O4 nanoparticles in an aqueous solution with 2.5 wt% gelatin. Whereas the dynamic viscosities obtained by fitting the model - extended by distributions of hydrodynamic diameters and viscosities - agree very well, the derived values for the shear modulus show the same temporal behavior during the gelation process, but vary approximately by a factor of two. To verify the values for viscosity and shear modulus obtained from nanorheology, macrorheological measurements are in progress.

  5. Electrical detection of magnetization dynamics via spin rectification effects

    Science.gov (United States)

    Harder, Michael; Gui, Yongsheng; Hu, Can-Ming

    2016-11-01

    The purpose of this article is to review the current status of a frontier in dynamic spintronics and contemporary magnetism, in which much progress has been made in the past decade, based on the creation of a variety of micro and nanostructured devices that enable electrical detection of magnetization dynamics. The primary focus is on the physics of spin rectification effects, which are well suited for studying magnetization dynamics and spin transport in a variety of magnetic materials and spintronic devices. Intended to be intelligible to a broad audience, the paper begins with a pedagogical introduction, comparing the methods of electrical detection of charge and spin dynamics in semiconductors and magnetic materials respectively. After that it provides a comprehensive account of the theoretical study of both the angular dependence and line shape of electrically detected ferromagnetic resonance (FMR), which is summarized in a handbook format easy to be used for analysing experimental data. We then review and examine the similarity and differences of various spin rectification effects found in ferromagnetic films, magnetic bilayers and magnetic tunnel junctions, including a discussion of how to properly distinguish spin rectification from the spin pumping/inverse spin Hall effect generated voltage. After this we review the broad applications of rectification effects for studying spin waves, nonlinear dynamics, domain wall dynamics, spin current, and microwave imaging. We also discuss spin rectification in ferromagnetic semiconductors. The paper concludes with both historical and future perspectives, by summarizing and comparing three generations of FMR spectroscopy which have been developed for studying magnetization dynamics.

  6. Breast imaging and reporting data system (BIRADS): magnetic resonance imaging.

    Science.gov (United States)

    Tardivon, Anne A; Athanasiou, Alexandra; Thibault, Fabienne; El Khoury, Carl

    2007-02-01

    This article reviews the technical aspects and interpretation criteria in breast MR imaging based on the first edition of breast imaging and reporting data system (BIRADS) published by the American College of Radiology (ACR) in 2003. In a second article, practical cases will be proposed for training the readers. The major aims of using this lexicon are: first to use a logical and standardized description of MR lesions, secondly to obtain a structured MR report with a clear final impression (BIRADS assessment categories), and thirdly to help comparison between different clinical studies based on similar breast MRI terminology.

  7. Breast imaging and reporting data system (BIRADS): Magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tardivon, Anne A. [Department of Radiology, Institut Curie, 26 rue d' Ulm, 75248 Paris Cedex 05 (France)]. E-mail: anne.tardivon@curie.net; Athanasiou, Alexandra [Department of Radiology, Institut Curie, 26 rue d' Ulm, 75248 Paris Cedex 05 (France); Thibault, Fabienne [Department of Radiology, Institut Curie, 26 rue d' Ulm, 75248 Paris Cedex 05 (France); El Khoury, Carl [Department of Radiology, Institut Curie, 26 rue d' Ulm, 75248 Paris Cedex 05 (France)

    2007-02-15

    This article reviews the technical aspects and interpretation criteria in breast MR imaging based on the first edition of breast imaging and reporting data system (BIRADS) published by the American College of Radiology (ACR) in 2003. In a second article, practical cases will be proposed for training the readers. The major aims of using this lexicon are: first to use a logical and standardized description of MR lesions, secondly to obtain a structured MR report with a clear final impression (BIRADS assessment categories), and thirdly to help comparison between different clinical studies based on similar breast MRI terminology.

  8. The Effect of Varying Magnetic Field Gradient on Combustion Dynamic

    Science.gov (United States)

    Suzdalenko, Vera; Zake, Maija; Barmina, Inesa; Gedrovics, Martins

    2011-01-01

    The focus of the recent experimental research is to provide control of the combustion dynamics and complex measurements (flame temperature, heat production rate, and composition of polluting emissions) for pelletized wood biomass using a non-uniform magnetic field that produces magnetic force interacting with magnetic moment of paramagnetic oxygen. The experimental results have shown that a gradient magnetic field provides enhanced mixing of the flame compounds by increasing combustion efficiency and enhancing the burnout of volatiles.

  9. A study of the breast cancer dynamics in North Carolina.

    Science.gov (United States)

    Christakos, G; Lai, J J

    1997-11-01

    This work is concerned with the study of breast cancer incidence in the State of North Carolina. Methodologically, the current analysis illustrates the importance of spatiotemporal random field modelling and introduces a mode of reasoning that is based on a combination of inductive and deductive processes. The composite space/time analysis utilizes the variability characteristics of incidence and the mathematical features of the random field model to fit it to the data. The analysis is significantly general and can efficiently represent non-homogeneous and non-stationary characteristics of breast cancer variation. Incidence predictions are produced using data at the same time period as well as data from other time periods and disease registries. The random field provides a rigorous and systematic method for generating detailed maps, which offer a quantitative description of the incidence variation from place to place and from time to time, together with a measure of the accuracy of the incidence maps. Spatiotemporal mapping accounts for the geographical locations and the time instants of the incidence observations, which is not usually the case with most empirical Bayes methods. It is also more accurate than purely spatial statistics methods, and can offer valuable information about the breast cancer risk and dynamics in North Carolina. Field studies could be initialized in high-rate areas identified by the maps in an effort to uncover environmental or life-style factors that might be responsible for the high risk rates. Also, the incidence maps can help elucidate causal mechanisms, explain disease occurrences at a certain scale, and offer guidance in health management and administration.

  10. Dynamic contrast-enhanced MRI for monitoring response to neoadjuvant chemotherapy in breast cancer

    OpenAIRE

    Loo, C E

    2016-01-01

    The general aim of this thesis is to investigate the role of dynamic contrast-enhanced MRI in monitoring response of breast cancer during neoadjuvant chemotherapy. The role of MRI with respect to achieving personalized breast cancer treatment by improving response monitoring is examined. Our findings demonstrate the potential clinical relevance of contrast-enhanced MRI for monitoring response of breast cancer during and after neoadjuvant chemotherapy. We defined MRI criteria ( reduction < 25%...

  11. Rotational dynamics of magnetic silica spheres studied by measuring the complex magnetic susceptibility

    NARCIS (Netherlands)

    Claesson, E.M.; Erne, B.H.; Philipse, A.P.

    2007-01-01

    The weak permanent magnetic dipole moment of cobalt ferrite-doped colloidal silica spheres was increased by exposure to a saturating magnetic field. The resulting change of the rotational dynamics of the magnetic microspheres in a weak alternating field was measured from low to high volume fraction

  12. Vascular characterisation of triple negative breast carcinomas using dynamic MRI

    Energy Technology Data Exchange (ETDEWEB)

    Li, Sonia P.; Beresford, Mark J.; Ah-See, Mei-Lin W.; Makris, Andreas [Mount Vernon Cancer Centre, Academic Oncology Unit, Northwood, Middlesex (United Kingdom); Padhani, Anwar R.; Taylor, N.J.; Stirling, J.J. [Mount Vernon Hospital, Paul Strickland Scanner Centre, Northwood, Middlesex (United Kingdom); D' Arcy, James A.; Collins, David J. [Royal Marsden NHS Foundation Trust and Institute of Cancer Research, CR UK and EPSRC Cancer Imaging Centre, Sutton, Surrey (United Kingdom)

    2011-07-15

    Triple-negative (ER-/PR-/HER2-) breast carcinomas (TNBC) are aggressive tumours with underexplored imaging features. This study investigates whether their vascular characteristics as assessed by dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast-enhanced (DSC) MRI are distinct from the prognostically more favourable ER+/PR+/HER2- cancers. Patients with primary breast cancer underwent MRI before neoadjuvant chemotherapy and were identified as ER-/PR-/HER2- or ER+/PR+/HER2- from core biopsy specimens. MRI parameters reflecting tissue perfusion, permeability, and extracellular leakage space were measured. Values for inflow transfer constant (K{sup trans}), outflow rate constant (k{sub ep}), leakage space (v{sub e}), area under the gadolinium curve (IAUGC{sub 60}), relative blood volume (rBV) and flow (rBF), and Mean Transit Time (MTT) were compared across receptor status and with known prognostic variables. Thirty seven patients were assessable in total (16 ER-/PR-/HER2-, 21 ER+/PR+/HER2-). Lower v{sub e} (p = 0.001), shorter MTT (p = 0.007) and higher k{sub ep} values (p = 0.044) were observed in TNBC. v{sub e} was lower across all T stages, node-negative (p = 0.004) and low-grade TNBC (p = 0.037). v{sub e} was the best predictor of triple negativity (ROC AUC 0.80). TNBC possess characteristic features on imaging, with lower extracellular space (higher cell density) and higher contrast agent wash-out rate (higher vascular permeability) suggesting a distinctive phenotype detectable by MRI. (orig.)

  13. Investigation of Dynamics of Self-Similarly Evolving Magnetic Clouds

    CERN Document Server

    Dalakishvili, Giorgi; Lapenta, Giovanni; Poedts, Stefaan

    2010-01-01

    Magnetic clouds (MCs) are "magnetized plasma clouds" moving in the solar wind. MCs transport magnetic flux and helicity away from the Sun. These structures are not stationary but feature temporal evolution. Commonly, simplified MC models are considered. The goal of the present study is to investigate the dynamics of more general, radially expanding MCs. They are considered as cylindrically symmetric magnetic structures with low plasma {\\beta}. In order to study MC`evolution the self-similar approach method and a numerical approach are used. It is shown that the forces are balanced in the considered self-similarly evolving, cylindrically symmetric magnetic structures. Explicit analytical expressions for magnetic field, plasma velocity, density and pressure within MCs are derived. These solutions are characterized by conserved values of magnetic flux and helicity. We also investigate the dynamics of self-similarly evolving MCs by means of the numerical code "Graale". In addition, their expansion in a medium wit...

  14. Nonlinear magnetization dynamics of antiferromagnetic spin resonance induced by intense terahertz magnetic field

    CERN Document Server

    Mukai, Y; Yamamoto, T; Kageyama, H; Tanaka, K

    2016-01-01

    We report on the nonlinear magnetization dynamics of a HoFeO3 crystal induced by a strong terahertz magnetic field resonantly enhanced with a split ring resonator and measured with magneto-optical Kerr effect microscopy. The terahertz magnetic field induces a large change (~40%) in the spontaneous magnetization. The frequency of the antiferromagnetic resonance decreases in proportion to the square of the magnetization change. A modified Landau-Lifshitz-Gilbert equation with a phenomenological nonlinear damping term quantitatively reproduced the nonlinear dynamics.

  15. Assessing magnetic nanoparticle aggregation in polymer melts by dynamic magnetic susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sierra-Bermúdez, Sergio [Department of Chemical Engineering, University of Puerto Rico, P.O. Box 9000 Mayaguez, PR 00681 PR (United States); Maldonado-Camargo, Lorena P. [Department of Chemical Engineering, University of Florida, 1006 Center Drive, Gainesville, FL 32603 (United States); Orange, François [Department of Physics and Nanoscopy Facility, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Guinel, Maxime J.-F. [Department of Physics and Nanoscopy Facility, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Department of Chemistry, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, PO Box 116131, Gainesville, FL 32611-6131 (United States)

    2015-03-15

    Aggregation of magnetic nanoparticles in polymer melts was assessed using dynamic magnetic susceptibility measurements. Magnetic nanocomposites consisting of polybutadiene/CoFe{sub 2}O{sub 4} and polystyrene/CoFe{sub 2}O{sub 4} mixtures were prepared using different techniques and characterized using dynamic magnetic susceptibility measurements. The presence of nanoparticle aggregates determined using magnetic measurements was confirmed with transmission electron microscopy examinations. The results were in good agreement with predictions from the Flory–Huggins interaction parameters. - Highlights: • Oleic acid coated magnetic nanoparticles (MNPs) were dispersed in polymer melts. • MNPs dispersed well in polybutadiene but not in polystyrene. • Dynamic magnetic susceptibility (DMS) measurements assessed presence of aggregates. • DMS predictions were confirmed by transmission electron microscopy. • The Flory-Huggins interaction parameter correlated with MNP dispersion.

  16. Magnetic stochasticity in magnetically confined fusion plasmas chaos of field lines and charged particle dynamics

    CERN Document Server

    Abdullaev, Sadrilla

    2014-01-01

    This is the first book to systematically consider the modern aspects of chaotic dynamics of magnetic field lines and charged particles in magnetically confined fusion plasmas.  The analytical models describing the generic features of equilibrium magnetic fields and  magnetic perturbations in modern fusion devices are presented. It describes mathematical and physical aspects of onset of chaos, generic properties of the structure of stochastic magnetic fields, transport of charged particles in tokamaks induced by magnetic perturbations, new aspects of particle turbulent transport, etc. The presentation is based on the classical and new unique mathematical tools of Hamiltonian dynamics, like the action--angle formalism, classical perturbation theory, canonical transformations of variables, symplectic mappings, the Poincaré-Melnikov integrals. They are extensively used for analytical studies as well as for numerical simulations of magnetic field lines, particle dynamics, their spatial structures and  statisti...

  17. Reluctance Network Based Dynamic Analysis in Power Magnetics

    Science.gov (United States)

    Nakamura, Kenji; Ichinokura, Osamu

    This paper describes a reluctance network based dynamic analysis method used in the field of power magnetics, which is called reluctance network analysis (RNA). It is based on the magnetic circuit method and has some advantages for simulating electrical machinery such as a simple analytical model, high calculation accuracy, and easy to combine with an electric circuit, motion and thermal dynamics. First, the basis of the magnetic circuit method is described. Next, two case studies of RNA, one is a permanent magnet (PM) motor and the another is a switched reluctance (SR) motor, are presented.

  18. Immune Response Augmentation in Metastasized Breast Cancer by Localized Therapy Utilizing Biocompatible Magnetic Fluids. Addendum

    Science.gov (United States)

    2009-08-01

    research is to assess the efficacy of augmenting immune responses to breast cancer through the use of magneto-rheological fluid (MRF), suspensions of...poly(NIPAAm) onto silica nanoparticles using ATRP has been investigated by [5, 6]. In the present work, MRFs were synthesized from suspensions of...of Iron-Based Nanofluids ”, International Journal of Modern Physics B, Vol. 21, pp. 4774 – 4781, 2007 18. J. P. Jakubovics, “Magnetism and Magnetic

  19. Imaging of Her2-targeted magnetic nanoparticles for breast cancer detection: comparison of SQUID-detected magnetic relaxometry and MRI.

    Science.gov (United States)

    Adolphi, Natalie L; Butler, Kimberly S; Lovato, Debbie M; Tessier, T E; Trujillo, Jason E; Hathaway, Helen J; Fegan, Danielle L; Monson, Todd C; Stevens, Tyler E; Huber, Dale L; Ramu, Jaivijay; Milne, Michelle L; Altobelli, Stephen A; Bryant, Howard C; Larson, Richard S; Flynn, Edward R

    2012-01-01

    Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, noninvasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by superconducting quantum interference device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 (breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125 000 nanoparticle-labeled cells at 3 cm from the SQUID sensors. T(2)-weighted MRI yielded a detection limit of 15 600 cells in a 150 µl volume, with r(1) = 1.1 mm(-1) s(-1) and r(2) = 166 mm(-1) s(-1). Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7 T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies.

  20. Ultrafast magnetization dynamics of lanthanide metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sultan, Muhammad

    2012-05-14

    In this study, the laser-induced magnetization dynamics of the lanthanide ferromagnets Gadolinium (Gd), Terbium (Tb) and their alloys is investigated using femtosecond (fs) time-resolved x-ray magnetic circular dichroism (XMCD), the magneto-optical Kerr effect (MOKE) and magnetic second harmonic generation (MSHG). The magnetization dynamics is analyzed from the time scale of a few fs up to several hundred picoseconds (ps). The contributions of electrons, phonons, spin fluctuations, as well as the temporal regimes corresponding to the spin-orbit and exchange interactions are disentangled. In addition to possible applications in magnetic storage devices, understanding magnetization dynamics in lanthanides is also important because of their different magnetic structure compared to well-studied itinerant ferromagnets. Lanthanides are model Heisenberg-ferromagnets with localized 4f magnetic moments and long range magnetic ordering through indirect exchange interaction. By optical excitation of the conduction electrons, which mediate the exchange interaction, and studying the induced dynamics of the localized 4f and delocalized 5d6s magnetic moments, one can obtain insight into the angular momentum transfer at ultrafast time scales. Moreover, lanthanides offer the possibility to tune spin-lattice coupling via the 4f shell occupation and the concomitant changes in the 4f spin and orbital moments due to Hund's rules. Utilizing this fact, the importance of spin-lattice coupling in laser-induced demagnetization is also analyzed by comparing the magnetization dynamics in Gd and Tb. By investigating the magnetization dynamics of localized 4f moments of Gd and Tb using time-resolved XMCD, it is found that the demagnetization proceeds in both metals in two time scales, following fs laser excitation, which are classified as: (i) non-equilibrium (t > 1 ps), with respect to equilibration of electron and phonon temperatures. The

  1. Dynamic contrast-enhanced MRI for monitoring response to neoadjuvant chemotherapy in breast cancer

    NARCIS (Netherlands)

    Loo, C.E.

    2016-01-01

    The general aim of this thesis is to investigate the role of dynamic contrast-enhanced MRI in monitoring response of breast cancer during neoadjuvant chemotherapy. The role of MRI with respect to achieving personalized breast cancer treatment by improving response monitoring is examined. Our finding

  2. Pharmacokinetic analysis of Gd-DTPA enhancement in dynamic three-dimensional MRI of breast lesions

    NARCIS (Netherlands)

    denBoer, JA; Hoenderop, RKKM; Smink, J; Dornseiffen, G; Koch, PWAA; Mulder, JH; Slump, CH; Volker, EDP; deVos, RAI

    1997-01-01

    The purpose of this study was to demonstrate that dynamic MRI covering both breasts can provide sensitivity for tumor detection as well as specificity and sensitivity for differentiation of tumor malignancy, Three-dimensional gradient echo scans were used covering both breasts. Before Gd-DTPA bolus

  3. Identification of occult breast lesions detected by magnetic resonance imaging with targeted ultrasound: A prospective study

    Energy Technology Data Exchange (ETDEWEB)

    Aracava, Márcia M., E-mail: marcia.aracava@gmail.com; Chojniak, Rubens, E-mail: chojniak@uol.com.br; Souza, Juliana A., E-mail: julianaalves79@hotmail.com; Bitencourt, Almir G.V., E-mail: almirgvb@yahoo.com.br; Marques, Elvira F., E-mail: elvira.marques@ig.com.br

    2014-03-15

    Objective: To verify the capacity of targeted ultrasound (US) to identify additional lesions detected on breast magnetic resonance imaging (MRI), but occult to initial mammography, US and clinical examinations. Methods: This prospective study included 68 additional relevant breast lesions identified on MRI of 49 patients. As an inclusion criterion, breast US and mammography were required and performed up to six months before MRI. These lesions were then subjected to targeted “second-look” US up to 2 weeks after MRI, performed by one or two radiologists with expertise on breast imaging. Lesions were evaluated according to the established Breast Imaging Report and Data System (BI-RADS) lexicon. Results: Targeted US identified 46/68 (67.6%) lesions revealed by MRI. No significant associations were observed between US identification and the type of lesion, dimensions, morphological characteristics and enhancement pattern according to MRI findings. Targeted US identified 100% of BI-RADS category 5 lesions, 90% of category 4 lesions, and just over 50% of category 3 lesions (p < 0.05). There was significant agreement (p < 0.001) between MRI and US BI-RADS classification for all three categories. Conclusion: Targeted US can identify a large proportion of the lesions detected by breast MRI, especially those at high risk of malignancy, when performed by a professional with experience in both breast US and MRI.

  4. Impact of value based breast cancer care pathway implementation on pre-operative breast magnetic resonance imaging utilization

    Science.gov (United States)

    McCray, Devina K. S.; Grobmyer, Stephen R.

    2017-01-01

    Background Bilateral breast magnetic resonance imaging (MRI) is commonly used in the diagnostic workup of breast cancer (BC) to assess extent of disease and identify occult foci of disease. However, evidence for routine use of pre-operative MRI is lacking. Breast MRI is costly and can lead to unnecessary tests and treatment delays. Clinical care pathways (care paths) are value-based guidelines, which define management recommendations derived by expert consensus and available evidence based data. At Cleveland Clinic, care paths created for newly diagnosed BC patients recommend selective use of pre-operative MRI. We evaluated the number of pre-operative MRIs ordered before and after implementing an institution wide BC care paths in April 2014. Methods A retrospective review was conducted of BC cases during the years 2012, 2014, and part of 2015. Patient, tumor and treatment characteristics were collected. Pre-operative MRI utilization was compared before and after care path implementation. Results We identified 1,515 BC patients during the study period. Patients were more likely to undergo pre-operative MRI in 2012 than 2014 (OR: 2.77; Pcare path indications. Conclusions Implementation of online BC care paths at our institution was associated with a decreased use of pre-operative MRI overall and in patients without a BC care path indication, driving value based care through the reduction of pre-operative breast MRIs. PMID:28210553

  5. Dynamics of disordered and frustrated magnets

    Science.gov (United States)

    Woo, Na Yoon

    Gd3Ga5O12 (GGG) is an insulating Heisenberg antiferromagnet. It is highly frustrated owing to its garnet structure, which is composed of elementary triangles with dominant antiferromagnetic interactions. We studied the effect of disorder in this geometrically frustrated system by changing the level of disorder in GGG:Ndx with x ranging from 0 to 1%. We measured the AC magnetic susceptibility in both the linear and nonlinear regimes and characterized the low temperature phases. As a result, we observed signatures of short range order in the 0% and 0.1% crystals, but not in the 1% sample, indicating that the order is suppressed in the 1% sample because of increasing frustration. The Nd doping compensates for the Gd-Ga off stoichiometry and pushes the system to a more perfectly frustrated state. We used the non-linear response to characterize the evolution of isolated spin clusters as a function of x. The Nd doping effectively relieves the net disorder. Hence the sample with the highest doping presents the smallest net correlated moments and the smallest onset field to activate the clusters from the background spin bath. The second project we report addresses the nonequilibrium dynamics of two related spin glasses. The model systems are the Ising magnets LiHo xY1--xF4 with x = 0.167 and 0.198. Although both systems undergo spin glass transitions, the mechanism that drives the phase transition is known to be different. The diluted sample is more affected by entanglement and in the concentrated system, the random field plays a more important role. In this thesis, we performed preliminary thermal and quantum aging experiments to compare the two systems. In the classical aging measurement, with temperature as the pertinent variable, the decay is exponential and measures primarily the response of the lattice. However quantum aging measurements using transverse field probe the spin relaxation character. The x = 0.167 and 0.198 crystals decay in opposite directions

  6. Vehicle Dynamics due to Magnetic Launch Propulsion

    Science.gov (United States)

    Galaboff, Zachary J.; Jacobs, William; West, Mark E.; Montenegro, Justino (Technical Monitor)

    2000-01-01

    The field of Magnetic Levitation Lind Propulsion (MagLev) has been around for over 30 years, primarily in high-speed rail service. In recent years, however, NASA has been looking closely at MagLev as a possible first stage propulsion system for spacecraft. This approach creates a variety of new problems that don't currently exist with the present MagLev trains around the world. NASA requires that a spacecraft of approximately 120,000 lbs be accelerated at two times the acceleration of gravity (2g's). This produces a greater demand on power over the normal MagLev trains that accelerate at around 0.1g. To be able to store and distribute up to 3,000 Mega Joules of energy in less than 10 seconds is a technical challenge. Another problem never addressed by the train industry and, peculiar only to NASA, is the control of a lifting body through the acceleration of and separation from the MagLev track. Very little is understood about how a lifting body will react with external forces, Such as wind gusts and ground effects, while being propelled along on soft springs such as magnetic levitators. Much study needs to be done to determine spacecraft control requirements as well as what control mechanisms and aero-surfaces should be placed on the carrier. Once the spacecraft has been propelled down the track another significant event takes place, the separation of the spacecraft from the carrier. The dynamics involved for both the carrier and the spacecraft are complex and coupled. Analysis of the reaction of the carrier after losing, a majority of its mass must be performed to insure control of the carrier is maintained and a safe separation of the spacecraft is achieved. The spacecraft angle of attack required for lift and how it will affect the carriage just prior to separation, along with the impacts of around effect and aerodynamic forces at ground level must be modeled and analyzed to define requirements on the launch vehicle design. Mechanisms, which can withstand the

  7. Brownian Dynamics of charged particles in a constant magnetic field

    CERN Document Server

    Hou, L J; Piel, A; Shukla, P K

    2009-01-01

    Numerical algorithms are proposed for simulating the Brownian dynamics of charged particles in an external magnetic field, taking into account the Brownian motion of charged particles, damping effect and the effect of magnetic field self-consistently. Performance of these algorithms is tested in terms of their accuracy and long-time stability by using a three-dimensional Brownian oscillator model with constant magnetic field. Step-by-step recipes for implementing these algorithms are given in detail. It is expected that these algorithms can be directly used to study particle dynamics in various dispersed systems in the presence of a magnetic field, including polymer solutions, colloidal suspensions and, particularly complex (dusty) plasmas. The proposed algorithms can also be used as thermostat in the usual molecular dynamics simulation in the presence of magnetic field.

  8. On the magnetism and dynamics of prominence legs hosting tornadoes

    CERN Document Server

    Gonzalez, M J Martinez; Arregui, I; Collados, M; Beck, C; Rodriguez, J de la Cruz

    2016-01-01

    Solar tornadoes are dark vertical filamentary structures observed in the extreme ultraviolet associated with prominence legs and filament barbs. Their true nature and relationship to prominences requires understanding their magnetic structure and dynamic properties. Recently, a controversy has arisen: is the magnetic field organized forming vertical, helical structures or is it dominantly horizontal? And concerning their dynamics, are tornadoes really rotating or is it just a visual illusion? Here, we analyze four consecutive spectropolarimetric scans of a prominence hosting tornadoes on its legs which help us shed some light on their magnetic and dynamical properties. We show that the magnetic field is very smooth in all the prominence, probably an intrinsic property of the coronal field. The prominence legs have vertical helical fields that show slow temporal variation probably related to the motion of the fibrils. Concerning the dynamics, we argue that 1) if rotation exists, it is intermittent, lasting no ...

  9. Dynamics of breast milk HIV-1 RNA with unilateral mastitis or abscess

    Science.gov (United States)

    Semrau, Katherine; Kuhn, Louise; Brooks, Daniel R.; Cabral, Howard; Sinkala, Moses; Kankasa, Chipepo; Thea, Donald M.; Aldrovandi, Grace M.

    2013-01-01

    Background Mastitis and abscess in HIV-infected women increase risk of breastfeeding transmission of HIV. Guidelines encourage women to stop breastfeeding on the affected breast and feed on the contralateral breast. However, impact of breast pathology on breast milk HIV dynamics is unknown. Methods HIV RNA was quantified in 211 breast milk samples collected before, during and after a clinical mastitis or abscess diagnosis from 38 HIV-infected women participating in a Zambian breastfeeding study. HIV RNA quantity was compared between affected and unaffected breasts over time using generalized estimating equation models. A sample of 115 women without breast pathology was selected as a control group. Results In the affected breast, breast milk HIV RNA quantity increased from the pre- to during-pathology period by log10 0.45 copies/mL (95% CI: 0.16, 0.74) and after symptom resolution, HIV RNA levels were no different from pre-pathology levels (log10 -0.04 copies/mL 95%CI: -0.33, 0.25). In the contralateral unaffected breast, HIV RNA quantity did not significantly increase (log10 0.15 copies/mL, 95% CI: -0.41, 0.10). Increase was more marked in women with abscess or with a greater number of mastitis symptoms. HIV RNA was not significantly different between affected and unaffected women, except at the time of diagnosis. Conclusions Breast milk HIV RNA increased modestly in the affected breast with unilateral mastitis or abscess and returned to pre-pathology levels with symptom resolution. Contralateral HIV RNA was not affected. Results support guidelines encouraging feeding from the contralateral breast to minimize risk of HIV transmission associated with unilateral breast pathology. PMID:23202812

  10. Protein dynamics from nuclear magnetic relaxation.

    Science.gov (United States)

    Charlier, Cyril; Cousin, Samuel F; Ferrage, Fabien

    2016-05-01

    Nuclear magnetic resonance is a ubiquitous spectroscopic tool to explore molecules with atomic resolution. Nuclear magnetic relaxation is intimately connected to molecular motions. Many methods and models have been developed to measure and interpret the characteristic rates of nuclear magnetic relaxation in proteins. These approaches shed light on a rich and diverse range of motions covering timescales from picoseconds to seconds. Here, we introduce some of the basic concepts upon which these approaches are built and provide a series of illustrations.

  11. Magnetic Dynamics of Fine Particles Studied by Inelastic Neutron Scattering

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Bødker, Franz; Mørup, Steen;

    2000-01-01

    We give an introduction to inelastic neutron scattering and the dynamic scattering function for magnetic nanoparticles. Differences between ferromagnetic and antiferromagnetic nanoparticles are discussed and we give a review of recent results on ferromagnetic Fe nanoparticles and canted antiferro......We give an introduction to inelastic neutron scattering and the dynamic scattering function for magnetic nanoparticles. Differences between ferromagnetic and antiferromagnetic nanoparticles are discussed and we give a review of recent results on ferromagnetic Fe nanoparticles and canted...

  12. Instability in magnetic materials with a dynamical axion field.

    Science.gov (United States)

    Ooguri, Hirosi; Oshikawa, Masaki

    2012-04-20

    It has been pointed out that axion electrodynamics exhibits instability in the presence of a background electric field. We show that the instability leads to a complete screening of an applied electric field above a certain critical value and the excess energy is converted into a magnetic field. We clarify the physical origin of the screening effect and discuss its possible experimental realization in magnetic materials where magnetic fluctuations play the role of the dynamical axion field.

  13. Incoherent magnetization dynamics in strain mediated switching of magnetostrictive nanomagnets

    Science.gov (United States)

    Bhattacharya, Dhritiman; Mamun Al-Rashid, Md; D'Souza, Noel; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2017-01-01

    Micromagnetic studies of the magnetization change in magnetostrictive nanomagnets subjected to stress are performed for nanomagnets of different sizes. The interplay between demagnetization, exchange and stress anisotropy energies is used to explain the rich physics of size-dependent magnetization dynamics induced by modulating stress anisotropy in planar nanomagnets. These studies have important implications for strain mediated ultralow energy magnetization control in nanomagnets and its application in energy-efficient nanomagnetic computing devices.

  14. Models for the dynamics of interacting magnetic nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Mørup, Steen

    1998-01-01

    A critical review of models for the dynamics of interacting magnetic nanoparticles is given. It is shown that the basic assumptions in the Dormann-Bessais-Fiorani model are unrealistic. The experimental observations on systems of interacting magnetic nanoparticles can, at least qualitatively...

  15. Preoperative axillary lymph node evaluation in breast cancer patients by breast magnetic resonance imaging (MRI): Can breast MRI exclude advanced nodal disease?

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Su Jeong [Yonsei University College of Medicine, Department of Radiology, Breast Cancer Clinic, Severance Hospital, Research Institute of Radiological Science, Seoul (Korea, Republic of); Hallym University Medical Center, Department of Radiology, Kangnam Sacred Heart Hospital, Seoul (Korea, Republic of); Kim, Eun-Kyung; Moon, Hee Jung; Yoon, Jung Hyun; Kim, Min Jung [Yonsei University College of Medicine, Department of Radiology, Breast Cancer Clinic, Severance Hospital, Research Institute of Radiological Science, Seoul (Korea, Republic of)

    2016-11-15

    To evaluate the diagnostic performance of breast magnetic resonance imaging (MRI) in preoperative evaluation of axillary lymph node metastasis (ALNM) in breast cancer patients and to assess whether breast MRI can be used to exclude advanced nodal disease. A total of 425 patients were included in this study and breast MRI findings were retrospectively reviewed. The diagnostic performance of breast MRI for diagnosis of ALNM was evaluated in all patients, patients with neoadjuvant chemotherapy (NAC), and those without NAC (no-NAC). We evaluated whether negative MRI findings (cN0) can exclude advanced nodal disease (pN2-pN3) using the negative predictive value (NPV) in each group. The sensitivity and NPV of breast MRI in evaluation of ALNM was 51.3 % (60/117) and 83.3 % (284/341), respectively. For cN0 cases on MRI, pN2-pN3 manifested in 1.8 % (6/341) of the overall patients, 0.4 % (1/257) of the no-NAC group, and 6 % (5/84) of the NAC group. The NPV of negative MRI findings for exclusion of pN2-pN3 was higher for the no-NAC group than for the NAC group (99.6 % vs. 94.0 %, p = 0.039). Negative MRI findings (cN0) can exclude the presence of advanced nodal disease with an NPV of 99.6 % in the no-NAC group. (orig.)

  16. A suspicious breast lesion detected by dynamic contrast-enhanced MRI and pathologically confirmed as capillary hemangioma: A case report and literature review

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lian He; Li, Qing Chang; Xu, Hong Tao; Wang, Xin; Wang, En Hua [The First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, Shenyang (China); Ma, Shuang [Dept. of Neurology, Sheng Jing Hospital of China Medical University, Shenyang (China)

    2013-12-15

    Breast capillary hemangioma is a type of benign vascular tumor which is rarely seen. Little is known about its presentation on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Here, we describe a case of suspicious breast lesion detected by DCE-MRI and pathologically confirmed as capillary hemangioma. Our case indicates that a small mass with a superficial location, clear boundary, and homogeneous enhancement on DCE-MRI indicates the possible diagnosis of hemangioma, whereby even the lesion presents a washout type curve.

  17. Magnetic phase diagrams based on static and dynamic magnetic behaviour in Ru-based superconducting ferromagnets.

    Science.gov (United States)

    Nigam, R; Pan, A V; Dou, S X

    2011-11-02

    In this work, we present magnetic phase diagrams of a RuSr(2)Eu(1.5)Ce(0.5)Cu(2)O(10-δ) (Ru-1222) superconducting ferromagnet derived from its static and dynamic magnetic responses, measured by temperature and field dependences of dc magnetization and nonlinear ac susceptibility in both low and high magnetic fields. Comparison of magnetic phase diagrams of phase pure and impure samples singles out the intrinsic and extrinsic magnetic features, naturally proposing a unified model of Ru-1222 magnetic behaviour. The results considered within the proposed interpretation indicate full agreement between static and dynamic properties which, if measured in combination, effectively complement each other, uncovering existing ambiguities.

  18. Preliminary investigations of magnetic modulated nanoparticles for microwave breast cancer detection

    Directory of Open Access Journals (Sweden)

    Ley S.

    2015-09-01

    Full Text Available This paper investigates the potential of magnetic modulated iron oxide nanoparticles in terms of a contrast enhancement for Ultra-wideband (UWB breast imaging. The work is motivated by the low dielectric contrast between tumor and normal glandular/fibroconnective tissue. The influence of an external polarizing magnetic field on pure and coated magnetite nanoparticles is investigated in this contribution. Measurements were conducted using M-sequence UWB technology and an oil-gelatin phantom. It is shown that a coating, which is necessary for clinical use, results in a lower signal response, and thus leads to a lower detectability of magnetic modulated nanoparticles.

  19. The magnetization transfer characteristics of human breast tissues: an in vitro NMR study

    Science.gov (United States)

    Callicott, C.; Thomas, J. M.; Goode, A. W.

    1999-05-01

    A series of freshly excised human breast tissues was analysed using a nuclear magnetic resonance spectrometer and then subjected to routine histopathology examination. Tissues comprised normal parenchymal, adipose, fibrocystic, fibroadenoma and malignant types. An inversion-recovery sequence performed both with and without magnetization transfer allowed T1, T1, and values to be obtained. From this information, the magnetization transfer rate constant, K, was calculated for each tissue sample. These data show that T1 provided greater discrimination between neoplasic and normal tissues than did T1. However, neither T1 nor K values provided a means of discriminating between benign and malignant disease.

  20. Three-dimensional in vitro co-culture model of breast tumor using magnetic levitation.

    Science.gov (United States)

    Jaganathan, Hamsa; Gage, Jacob; Leonard, Fransisca; Srinivasan, Srimeenakshi; Souza, Glauco R; Dave, Bhuvanesh; Godin, Biana

    2014-10-01

    In this study, we investigate a novel in vitro model to mimic heterogeneous breast tumors without the use of a scaffold while allowing for cell-cell and tumor-fibroblast interactions. Previous studies have shown that magnetic levitation system under conventional culturing conditions results in the formation of three-dimensional (3D) structures, closely resembling in vivo tissues (fat tissue, vasculature, etc.). Three-dimensional heterogeneous tumor models for breast cancer were designed to effectively model the influences of the tumor microenvironment on drug efficiency. Various breast cancer cells were co-cultured with fibroblasts and then magnetically levitated. Size and cell density of the resulting tumors were measured. The model was phenotypically compared to in vivo tumors and examined for the presence of ECM proteins. Lastly, the effects of tumor stroma in the 3D in vitro model on drug transport and efficiency were assessed. Our data suggest that the proposed 3D in vitro breast tumor is advantageous due to the ability to: (1) form large-sized (millimeter in diameter) breast tumor models within 24 h; (2) control tumor cell composition and density; (3) accurately mimic the in vivo tumor microenvironment; and (4) test drug efficiency in an in vitro model that is comparable to in vivo tumors.

  1. Magnetic resonance imaging (MRI) evaluation of residual breast tissue following mastectomy and reconstruction with silicone implants.

    Science.gov (United States)

    Zippel, Douglas; Tsehmaister-Abitbol, Vered; Rundstein, Arie; Shalmon, Anat; Zbar, Andrew; Nardini, Gil; Novikov, Ilya; Sklair-Levy, Miri

    2015-01-01

    We present our use of magnetic resonance (MR) measurement to determine the amount of residual breast tissue (RBT) following total mastectomy with reconstruction. Breast MR images of 45 women who underwent surgery between January and November 2011 were reviewed. The cohort included therapeutic and prophylactic mastectomies. RBT was evaluated at four points with a digital caliper assessing T2-weighted and T1-weighted images. Patients undergoing mastectomy for carcinoma tended to have less RBT than in prophylactic surgery. Greater age and recent surgery both correlated with larger RBT. Variable thickness of RBT is demonstrable following mastectomy and implant reconstruction using MR imaging. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Magnetization dynamics induced by Rashba effect in a Permalloy nanodisk

    Science.gov (United States)

    Li, Huanan; Hua, Zhong; Li, Dongfei

    2017-02-01

    Magnetic vortex dynamics mediated by spin-polarized ac current of different amplitudes and frequencies are investigated by micromagnetic simulations in a system lacking structure inversion symmetry. Micromagnetic calculations reveal that the critical current density required to induce vortex core reversal may be decreased to below 1010 A m-2 due to strong transverse magnetic field by Rashba effect. We also find the spin torque of ac current plays a trivial role in magnetic vortex dynamics in a broken inversion symmetry system when the current density is on the order of 1010 A m-2 and the current with frequency close to the vortex eigenfrequency is the most efficient for reversal.

  3. Current and emerging quantitative magnetic resonance imaging methods for assessing and predicting the response of breast cancer to neoadjuvant therapy

    Directory of Open Access Journals (Sweden)

    Abramson RG

    2012-10-01

    Full Text Available Richard G Abramson,1,2,9 Lori R Arlinghaus,1,2 Jared A Weis,1,2 Xia Li,1,2 Adrienne N Dula,1,2 Eduard Y Chekmenev,1–4,9 Seth A Smith,1–3,5 Michael I Miga,1–3,6 Vandana G Abramson,7,9 Thomas E Yankeelov1–3,5,8,91Institute of Imaging Science, 2Department of Radiology and Radiological Sciences, 3Department of Biomedical Engineering, 4Department of Biochemistry, 5Department of Physics, 6Department of Neurosurgery, 7Department of Medical Oncology, 8Department of Cancer Biology, 9Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville,TN, USAAbstract: Reliable early assessment of breast cancer response to neoadjuvant therapy (NAT would provide considerable benefit to patient care and ongoing research efforts, and demand for accurate and noninvasive early-response biomarkers is likely to increase. Response assessment techniques derived from quantitative magnetic resonance imaging (MRI hold great potential for integration into treatment algorithms and clinical trials. Quantitative MRI techniques already available for assessing breast cancer response to neoadjuvant therapy include lesion size measurement, dynamic contrast-enhanced MRI, diffusion-weighted MRI, and proton magnetic resonance spectroscopy. Emerging yet promising techniques include magnetization transfer MRI, chemical exchange saturation transfer MRI, magnetic resonance elastography, and hyperpolarized MR. Translating and incorporating these techniques into the clinical setting will require close attention to statistical validation methods, standardization and reproducibility of technique, and scanning protocol design.Keywords: treatment response, presurgical treatment, neoadjuvant chemotherapy

  4. Curcumin-loaded magnetic nanoparticles for breast cancer therapeutics and imaging applications

    Directory of Open Access Journals (Sweden)

    Yallapu MM

    2012-04-01

    Full Text Available Murali M Yallapu1, Shadi F Othman2, Evan T Curtis2, Nichole A Bauer1, Neeraj Chauhan1,3, Deepak Kumar4,5, Meena Jaggi1,3,6, Subhash C Chauhan1,3,61Cancer Biology Research Center, Sanford Research/University of South Dakota, Sioux Falls, SD, 2Department of Biological Systems Engineering, University of Nebraska–Lincoln, Lincoln, NE, 3Basic Biomedical Science Division, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD, 4Cancer Research Laboratory, Department of Biology, University of the District of Columbia, 5Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, 6Department of Obstetrics/Gynecology, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD, USABackground: The next generation magnetic nanoparticles (MNPs with theranostic applications have attracted significant attention and will greatly improve nanomedicine in cancer therapeutics. Such novel MNP formulations must have ultra-low particle size, high inherent magnetic properties, effective imaging, drug targeting, and drug delivery properties. To achieve these characteristic properties, a curcumin-loaded MNP (MNP-CUR formulation was developed.Methods: MNPs were prepared by chemical precipitation method and loaded with curcumin (CUR using diffusion method. The physicochemical properties of MNP-CUR were characterized using dynamic light scattering, transmission electron microscopy, and spectroscopy. The internalization of MNP-CUR was achieved after 6 hours incubation with MDA-MB-231 breast cancer cells. The anticancer potential was evaluated by a tetrazolium-based dye and colony formation assays. Further, to prove MNP-CUR results in superior therapeutic effects over CUR, the mitochondrial membrane potential integrity and reactive oxygen species generation were determined. Magnetic resonance imaging capability and magnetic targeting property were also evaluated.Results: MNP-CUR exhibited individual particle grain size of ~9 nm

  5. Detection and Evaluation of Early Breast Cancer via Magnetic Resonance Imaging: Studies of Mouse Models and Clinical Implementation

    Science.gov (United States)

    2008-03-01

    K, Degani H. Magnetic reso- nance imaging reveals functional diversity of the vasculature in benign and malignant breast lesions. Cancer 2005;104:708...resonance imaging reveals functional diversity of the vasculature in benign and malignant breast lesions. Cancer 2005;104(4):708-718. 18. Tofts PS...resonance imaging reveals functional diversity of the vasculature in benign and malignant breast lesions. Cancer 2005;104(4):708-718. 405 9. Tofts PS

  6. Structure and dynamics of magnetic nanoparticles

    DEFF Research Database (Denmark)

    Clausen, K.N.; Bødker, F.; Hansen, M.F.

    2000-01-01

    In this paper we present X-ray and neutron diffraction data illustrating aspects of crystal and magnetic structures of ferromagnetic alpha-Fe and antiferromagnetic NiO nanoparticles, as well as inelastic neutron scattering studies of the magnetic fluctuations in NiO and in canted antiferromagneti...... alpha-Fe2O3. In the inelastic case we make use of the fact that we can study both the superparamagnetic relaxation and collective magnetic excitations of the whole particle moment at the antiferromagnetic Bragg positions. (C) 2000 Elsevier Science B.V. All rights reserved....

  7. The use of magnetic resonance mammography in women at increased risk for developing breast cancer

    Science.gov (United States)

    Popiela, Tadeusz J.; Herman-Sucharska, Izabela; Urbanik, Andrzej

    2012-01-01

    Introduction The use of conventional imaging techniques, namely mammography (MMG) and ultrasound (US), for breast cancer (BC) detection in women at high risk for the disease does not bring optimal results in many cases. Aim The present study evaluated the effectiveness of magnetic resonance (MR) mammography (MRM) in cases where US and MMG failed to detect suspected breast lesions. Material and methods The study group consisted of 379 women who had had no breast pathologies detected by US and MMG. This group was then divided into 4 groups according to the relative risk of breast cancer development. All the women underwent MRM, and any breast pathology detected by MRM was then verified by open surgical biopsy (OSB). Results Based on the MRM findings, 37 women with breast pathologies were identified. All detected pathologies were then classified into one of the BIRADS (Breast Imaging Reporting and Data System) categories. Of these, 33 patients underwent open surgical biopsy. There were a total of 17 benign and 16 malignant breast pathologies that were not visualized by US and MMG. The types of malignancies found, in order of their frequency, were as follows: invasive ductal carcinoma (11 cases), ductal carcinoma in situ (2 cases), invasive lobular carcinoma (2 cases), and lobular carcinoma in situ (1 case). An analysis of MRM effectiveness in detecting BC showed 93.7% sensitivity and 64.71% specificity. Conclusions All women with a 20% or greater lifetime risk of developing BC should undergo annual MRM as a diagnostic adjunct to US and MMG. PMID:23630555

  8. Magnetic dynamics of weakly and strongly interacting hematite nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Bender Koch, Christian; Mørup, Steen

    2000-01-01

    The magnetic dynamics of two differently treated samples of hematite nanoparticles from the same batch with a particle size of about 20 nm have been studied by Mossbauer spectroscopy. The dynamics of the first sample, in which the particles are coated and dispersed in water, is in accordance.......3(-0.8)(+1.0) x 10(-10) s for a rotation of the sublattice magnetization directions in the rhombohedral (111) plane. The corresponding median superparamagnetic blocking temperature is about 150 K. The dynamics of the second, dry sample, in which the particles are uncoated and thus allowed to aggregate, is slowed...... down by interparticle interactions and a magnetically split spectrum is retained at room temperature. The temperature variation or the magnetic hyperfine field, corresponding to different quantiles in the hyperfine field distribution, can be consistently described by a mean field model...

  9. In vitro investigation on the magnetic thermochemotherapy mediated by magnetic nanoparticles combined with methotrexate for breast cancer treatment.

    Science.gov (United States)

    Zhao, Lingyun; Huo, Meijun; Liu, Jiayi; Yao, Zhu; Li, Danye; Zhao, Zhiwei; Tang, Jintian

    2013-02-01

    Cancer comprehensive treatment has been fully recognized as it can provide an effective multimodality approach for fighting cancers. In therapeutic oncology, hyperthermic adjuvant chemotherapy termed as thermochemotherapy plays an increasing role in multimodality cancer treatment. Currently, targeted nanothermotherapy is one of the effective hyperthermia approach based on magnetic nanoparticles (MNPs), which can be achieved by applying biocompatible nanoscaled metallic particles that convert electromagnetic energy into heat, for instance, magnetic fluid hyperthermia (MFH) mediated by superparamagnetic iron oxide nanoparticles (SPIONs). Upon exposure under alternative magnetic field (AMF), SPIONs can generate heat through oscillation of their magnetic moment. Nowadays, clinical trials at phase II are now under investigations for MFH on patients in Germany and Japan and demonstrate very inspiring for cancer therapy. In this work we explore the feasibility and effectiveness of magnetic thermochemotherapy mediated by magnetic nanoparticles combined with methotrexate, an anti-cancer drug, for breast cancer comprehensive treatment. Amino silane coated MNPs as agent of MFH were prepared by the chemical precipitation method. Physiochemical characterizations on MNPs have been systematically carried out by various instrumental analyses. Inductive heating property of the MNPs was evaluated by monitoring the temperature increase of the MNPs suspension under AMF. The in-vitro cytotoxicity results on human breast cancer cell MCF-7 by CCK-8 assay indicated the bi-modal cancer treatment approach for combined MFH and chemotherapy is more effective than mono-modal treatment, indicating a thermal enhancement effect of hyperthermia on drug cytocoxicity. The magnetic thermochemotherapy mediated by MNPs combined with methotrexate can realize cancer comprehensive treatment thus has great potential in clinical application.

  10. Exploring the Origin and Dynamics of Solar Magnetic Fields

    CERN Document Server

    Hazra, Soumitra

    2016-01-01

    The Sun is a magnetically active star and is the source of the solar wind, electromagnetic radiation and energetic particles which affect the heliosphere and the Earths atmosphere. The magnetic field of the Sun is responsible for most of the dynamic activity of the Sun. This thesis research seeks to understand solar magnetic field generation and the role that magnetic fields play in the dynamics of the solar atmosphere. Specifically, this thesis focuses on two themes: in the first part, we study the origin and behaviour of solar magnetic fields using magnetohydrodynamic dynamo theory and modelling, and in the second part, utilizing observations and data analysis we study two major problems in solar physics, namely, the coronal heating problem and initiation mechanisms of solar flares.

  11. Edge states and skyrmion dynamics in nanostripes of frustrated magnets

    Science.gov (United States)

    Leonov, A. O.; Mostovoy, M.

    2017-01-01

    Magnetic skyrmions are particle-like topological excitations recently discovered in chiral magnets. Their small size, topological protection and the ease with which they can be manipulated by electric currents generated much interest in using skyrmions for information storage and processing. Recently, it was suggested that skyrmions with additional degrees of freedom can exist in magnetically frustrated materials. Here, we show that dynamics of skyrmions and antiskyrmions in nanostripes of frustrated magnets is strongly affected by complex spin states formed at the stripe edges. These states create multiple edge channels which guide the skyrmion motion. Non-trivial topology of edge states gives rise to complex current-induced dynamics, such as emission of skyrmion–antiskyrmion pairs. The edge-state topology can be controlled with an electric current through the exchange of skyrmions and antiskyrmions between the edges of a magnetic nanostructure. PMID:28240226

  12. The diagnosis of silicone breast-implant rupture: clinical findings compared with findings at magnetic resonance imaging

    DEFF Research Database (Denmark)

    Hölmich, Lisbet Rosenkrantz; Fryzek, Jon P; Kjøller, Kim;

    2005-01-01

    The objective was to evaluate the usefulness of clinical examination in the evaluation of breast-implant integrity, using the diagnosis at magnetic resonance imaging (MRI) as the "gold standard." Fifty-five women with 109 implants underwent a breast examination either just before or shortly after...

  13. Magnetic Resonance Spectroscopy of the Breast at 3T: Pre- and Post-Contrast Evaluation for Breast Lesion Characterization

    Directory of Open Access Journals (Sweden)

    E. Kousi

    2012-01-01

    Full Text Available Purpose. To determine whether in vivo proton magnetic resonance spectroscopy at 3T can provide accurate breast lesion characterization, and to determine the effect of gadolinium on the resonance of tCho. Methods. Twenty-four positive-mammogram patients were examined on a 3T MR scanner. 1H-MRS was performed before and after gadolinium administration. tCho peak was qualitatively evaluated before and after contrast injection. Results. Fourteen out of 27 lesions proved to be malignant after histopathological diagnosis. Using 1H-MRS, before contrast injection, 6/14 confirmed malignancies and 11/13 benign lesions were correctly classified; while, after contrast injection, 11/14 confirmed malignancies and 12/13 benign processes were correctly classified. Post gadolinium 1H-MRS proved useful in picking up tCho signal, improving the overall accuracy, sensitivity, and specificity by 35%, 83%, and 9%, respectively. Conclusion. 1H-MRS overall accuracy, sensitivity, and specificity in detecting breast lesion’s malignancy were increased after gadolinium administration. It is prudent to perform 1H-MRS before contrast injection in large breast lesions to avoid choline underestimation. In cases of small or non-mass lesions, it is recommended to perform 1H-MRS after contrast injection for better voxel prescription to enable a reliable preoperative diagnosis.

  14. Magnetization dynamics and spin pumping induced by standing elastic waves

    Science.gov (United States)

    Azovtsev, A. V.; Pertsev, N. A.

    2016-11-01

    The magnetization dynamics induced by standing elastic waves excited in a thin ferromagnetic film is described with the aid of micromagnetic simulations taking into account the magnetoelastic coupling between spins and lattice strains. Our calculations are based on the numerical solution of the Landau-Lifshitz-Gilbert equation comprising the damping term and the effective magnetic field with all relevant contributions. The simulations have been performed for 2-nm-thick F e81G a19 film dynamically strained by longitudinal and transverse standing waves with various frequencies, which span a wide range around the resonance frequency νres of coherent magnetization precession in unstrained F e81G a19 film. It is found that standing elastic waves give rise to complex local magnetization dynamics and spatially inhomogeneous dynamic patterns in the form of standing spin waves with the same wavelength. Remarkably, the amplitude of magnetization precession does not go to zero at nodes of these spin waves, which cannot be precisely described by simple analytical formulae. In the steady-state regime, magnetization oscillates with the frequency of the elastic wave, except in the case of longitudinal waves with frequencies well below νres, where the magnetization precesses with variable frequency strongly exceeding the wave frequency. The results obtained for the magnetization dynamics driven by elastic waves are used to calculate the spin current pumped from the dynamically strained ferromagnet into adjacent paramagnetic metal. Numerical calculations demonstrate that the transverse charge current in the paramagnetic layer, which is created by the spin current via inverse spin Hall effect, is high enough to be measured experimentally.

  15. Research on Dynamic Model's Building of Active Magnetic Suspension Systems

    Institute of Scientific and Technical Information of China (English)

    SHI Jian; YAN Guo-zheng; LI Li-chuan; WANG Kun-dong

    2006-01-01

    An experimental method is introduced in this paper to build the dynamics of AMSS (the active magnetic suspension system), which doesn't depend on system's physical parameters. The rotor can be reliably suspended under the unit feedback control system designed with the primary dynamic model obtained. Online identification in frequency domain is processed to give the precise model. Comparisons show that the experimental method is much closer to the precise model than the theoretic method based on magnetic circuit law. So this experimental method is a good choice to build the primary dynamic model of AMSS.

  16. Magnetic dynamics of ferrofluids: mathematical models and experimental investigations

    Science.gov (United States)

    Wu, Kai; Tu, Liang; Su, Diqing; Wang, Jian-Ping

    2017-03-01

    Magnetite ferrofluids with unique magnetic behaviors are attractive for biomedical applications such as magnetic fluid hyperthermia and magnetic particle imaging. A precise nanoparticle-specific characterization by theoretical models and experiments to predict dynamics of ferrofluids and optimize their behaviors for emerging biomedical applications is necessary. In this paper, combining experiments and modeling, we have uncovered interesting magnetic dynamics of nanoparticles that are dependent on magnetic field strength, polymer coating of nanoparticles, viscosity of ferrofluid, and dipolar interactions. It is concluded that either by changing the magnitude of magnetic field or the concentrations of nanoparticles, we are able to convert the dominating relaxation process of magnetic nanoparticles from Néel to Brownian, and vice versa. Polymer coatings on nanoparticles and viscosity of ferrofluids are demonstrated to have varying degrees of influence on effective relaxation times of nanoparticles with different sizes and under different field strengths. Our theoretical models are used to predict the magnetic response of ferrofluid consisting of 35 nm magnetite nanoparticles under alternating magnetic fields, and it turns out that our theoretical data fits well with the experimental data.

  17. Dynamical Axion Field in a Magnetic Topological Insulator Superlattice

    Science.gov (United States)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    We propose that the dynamical axion field can be realized in a magnetic topological insulator superlattice or a topological paramagnetic insulator. The magnetic fluctuations of these systems produce a pseudoscalar field which has an axionic coupling to the electromagnetic field, and thus it gives a condensed-matter realization of the axion electrodynamics. Compared to the previously proposed dynamical axion materials where a long range antiferromagnetic order is required, the systems proposed here have the advantage that only an uniform magnetization or a paramagnetic state is needed for the dynamic axion. We further propose several experiments to detect such a dynamical axion field. This work is supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Contract No. DE-AC02-76SF00515.

  18. Ability of subtraction and dynamic MR imaging to detect breast tumors. Comparison with ultrasonography and mammography

    Energy Technology Data Exchange (ETDEWEB)

    Terao, Eri; Takeuchi, Hiroaki; Iwamura, Akira; Murakami, Yoshitaka; Harada, Junta; Tada, Shinpei (Jikei Univ., Tokyo (Japan). School of Medicine)

    1994-09-01

    We evaluated the ability of subtraction and dynamic MR imaging to accurately detect breast tumors. Sixty-five breast carcinomas and 24 fibroadenomas were examined by an SE pulse sequence using a 0.2 Tesla unit. Subtraction MR images were obtained every minute during dynamic study with Gd-DTPA. Almost all breast tumors were seen as very bright masses, and the margin of the mass was clearly demonstrated on subtraction MR images. Breast carcinomas and fibroadenomas showed characteristic time-intensity curves on dynamic study. Time-intensity curves of the early peak type and plateau type were seen in 97% of breast carcinomas, while the gradually increasing type was seen in 92% of fibroadenomas. The detectability of breast carcinoma was 98% by MRI, 98% by ultrasonography, and 87% by mammography. That of fibroadenoma was 95% by MRI, 91% by ultrasonography and 60% by mammography. Sensitivity and specificity for breast carcinoma were 98% and 92% for MRI and 97% and 71% for ultrasonography. For fibroadenoma, they were 96% and 98% for MRI and 89% and 92% for ultrasonography. (author).

  19. Dynamic bilateral contrast-enhanced MR imaging of the breast: trade-off between spatial and temporal resolution.

    Science.gov (United States)

    Kuhl, Christiane K; Schild, Hans H; Morakkabati, Nuschin

    2005-09-01

    To investigate prospectively the trade-off between temporal and spatial resolution in dynamic contrast material-enhanced bilateral magnetic resonance (MR) imaging of the breast. Informed consent and institutional review board approval were obtained. An intraindividual comparative study was performed in 30 patients (mean age, 53 years; age range, 27-70 years) with a total of 54 enhancing lesions (28 benign and 26 malignant) who underwent dynamic MR imaging of the breast twice, once with a standard dynamic protocol (256 x 256 matrix, 69 seconds per acquisition) and once on a separate day with a modified dynamic protocol (400 x 512 matrix, 116 seconds per acquisition). Systematic qualitative analysis of morphologic features and region-of-interest-based analysis of enhancement kinetics were performed. A statistically significant difference (generalized linear modeling) in enhancement rates of benign versus malignant lesions was lost when moving from the standard to the modified dynamic protocol. Kinetic information on signal intensity time course patterns was preserved. Delineation of lesion margins and internal architecture was clearly superior with the modified dynamic protocol, which allowed identification of lesion features associated with high positive predictive value or high negative predictive value for breast cancer. Ten benign lesions classified as Breast Imaging Reporting and Data System (BI-RADS) category 3 with the standard protocol were correctly downgraded to BI-RADS category 2 with the modified protocol owing to visualization of internal septations. Thirteen malignant lesions categorized as BI-RADS category 3 or 4 with the standard protocol were correctly upgraded to BI-RADS category 4 or 5 with the modified protocol owing to visualization of spicules or rim enhancement. Receiver operating characteristic analysis revealed a significantly larger area under the curve for results obtained with the modified dynamic protocol. Increased spatial resolution

  20. Electric-field-driven dynamics of magnetic domain walls in magnetic nanowires patterned on ferroelectric domains

    OpenAIRE

    Van de Wiele, Ben; Leliaert, Jonathan; Franke, Kévin; van Dijken, Sebastiaan

    2016-01-01

    Strong coupling of magnetic domain walls onto straight ferroelastic boundaries of a ferroelectric layer enables full and reversible electric-field control of magnetic domain wall motion. In this paper, the dynamics of this new driving mechanism is analyzed using micromagnetic simulations. We show that transverse domain walls with a near-180° spin structure are stabilized in magnetic nanowires and that electric fields can move these walls with high velocities. Above a critical velocity, which ...

  1. Magnetization reversal dynamics in antiferromagnetically coupled magnetic recording media

    Science.gov (United States)

    Schabes, Manfred

    2002-03-01

    Antiferromagnetically coupled (AFC) media have been shown to provide an important extension of longitudinal magnetic data storage at high bit densities.[1,2] In this work we report the results of micromagnetic calculations to examine the magnetization reversal mechanism in two-layer AFC media as a function of bottom layer thickness and interfacial exchange coupling. It is shown that the magnetization reversal in the top and bottom layers can proceed at rather different time scales, if the interfacial energy density is small or the bottom layer thickness is large. In this case the reversal of the bottom layer may involve spin wave like oscillations that require time periods for damping that are large compared to the reversal time of the top layer. Detailed solutions of the Landau-Lifshitz-Langevin[2] equations are discussed to study these novel oscillatory excitations in AFC media at a temperature of 350 K. [1] E.E. Fullerton et al., Appl. Phys. Lett., vol.77, (2000),3806. [2] M.E. Schabes et al., IEEE Trans. Mag. MAG-37, (2001), 1432.

  2. Magnetic resonance imaging on complications of breast augmentation with injected hydrophilic polyacrylamide gel

    Institute of Scientific and Technical Information of China (English)

    XU Li-ying; KONG Xiang-quan; TIAN Zhi-xiong; QIU Da-sheng

    2006-01-01

    @@ The injection augmentation mammaplasty for cosmetic purpose has been popular recently in China. Two kinds of injectable material are used clinically, autologous fat and biomaterial. The fat injection for breast augmentation is in question with the major problems of progressive fat re-absorption,microcalcification, and fat liquefaction.1 Now, the principal alloplastic biomaterial for injection augmentation mammaplasty in China is hydrophilic polyacrylamide gel (HPAAG). Although thousands of breasts have been augmented with HPAAG and it seems to be a good biocompatible material, some complications develop after HPAAG injection augmentation mammaplasty.2-4 The patients had to undergo surgery to remove the injected HPAAG and associated lesions. Ultrasonography or magnetic resonance imaging (MRI) should be taken preoperatively to demonstrate the distribution of injected HPAAG and associated lesions.5 In this report, the diagnostic value and clinical significance of MRI on the complications of HPAAG breast augmentation were discussed.

  3. Magnetic-flux dynamics of high-Tc superconductors in weak magnetic fields

    DEFF Research Database (Denmark)

    Il’ichev, E. V.; Jacobsen, Claus Schelde

    1994-01-01

    Aspects of magnetic-flux dynamics in different types of samples of the high-temperature superconductor YBa2Cu3Ox have been investigated in magnetic fields below 1 Oe and at 77 K. The experiments were carried out in an arrangement including a field coil, a flat sample perpendicular to the field...

  4. 3.0 Tesla vs 1.5 Tesla breast magnetic resonance imaging in newly diagnosed breast cancer patients.

    Science.gov (United States)

    Butler, Reni S; Chen, Christine; Vashi, Reena; Hooley, Regina J; Philpotts, Liane E

    2013-08-28

    To compare 3.0 Tesla (T) vs 1.5T magnetic resonance (MR) imaging systems in newly diagnosed breast cancer patients. Upon Institutional Review Board approval, a Health Insurance Portability and Accountability Act-compliant retrospective review of 147 consecutive 3.0T MR examinations and 98 consecutive 1.5T MR examinations in patients with newly diagnosed breast cancer between 7/2009 and 5/2010 was performed. Eleven patients who underwent neoadjuvant chemotherapy in the 3.0T group were excluded. Mammographically occult suspicious lesions (BIRADS Code 4 and 5) additional to the index cancer in the ipsilateral and contralateral breast were identified. Lesion characteristics and pathologic diagnoses were recorded, and results achieved with both systems compared. Statistical significance was analyzed using Fisher's exact test. In the 3.0T group, 206 suspicious lesions were identified in 55% (75/136) of patients and 96% (198/206) of these lesions were biopsied. In the 1.5T group, 98 suspicious lesions were identified in 53% (52/98) of patients and 90% (88/98) of these lesions were biopsied. Biopsy results yielded additional malignancies in 24% of patients in the 3.0T group vs 14% of patients in the 1.5T group (33/136 vs 14/98, P = 0.07). Average size and histology of the additional cancers was comparable. Of patients who had a suspicious MR imaging study, additional cancers were found in 44% of patients in the 3.0T group vs 27% in the 1.5T group (33/75 vs 14/52, P = 0.06), yielding a higher positive predictive value (PPV) for biopsies performed with the 3.0T system. 3.0T MR imaging detected more additional malignancies in patients with newly diagnosed breast cancer and yielded a higher PPV for biopsies performed with the 3.0T system.

  5. Hamiltonian and Lagrangian Dynamical Matrix Approaches Applied to Magnetic Nanostructures

    Directory of Open Access Journals (Sweden)

    Roberto Zivieri

    2012-01-01

    Full Text Available Two micromagnetic tools to study the spin dynamics are reviewed. Both approaches are based upon the so-called dynamical matrix method, a hybrid micromagnetic framework used to investigate the spin-wave normal modes of confined magnetic systems. The approach which was formulated first is the Hamiltonian-based dynamical matrix method. This method, used to investigate dynamic magnetic properties of conservative systems, was originally developed for studying spin excitations in isolated magnetic nanoparticles and it has been recently generalized to study the dynamics of periodic magnetic nanoparticles. The other one, the Lagrangian-based dynamical matrix method, was formulated as an extension of the previous one in order to include also dissipative effects. Such dissipative phenomena are associated not only to intrinsic but also to extrinsic damping caused by injection of a spin current in the form of spin-transfer torque. This method is very accurate in identifying spin modes that become unstable under the action of a spin current. The analytical development of the system of the linearized equations of motion leads to a complex generalized Hermitian eigenvalue problem in the Hamiltonian dynamical matrix method and to a non-Hermitian one in the Lagrangian approach. In both cases, such systems have to be solved numerically.

  6. Morphology and dynamics of photospheric and chromospheric magnetic fields

    CERN Document Server

    Wöger, F; Rimmele, T

    2009-01-01

    We use joint observations obtained with the Hinode space observatory and the Interferometric Bidimensional Spectrometer (IBIS) installed at the DST of the NSO/SP to investigate the morphology and dynamics of (a) non-magnetic and (b) magnetic regions in the fluctosphere. In inter-network regions with no significant magnetic flux contributions above the detection limit of IBIS, we find intensity structures with similar characteristics as those seen in numerical simulations by Wedemeyer-B\\"ohm (2008). The magnetic flux elements in the network are stable and seem to resemble the spatially extended counterparts to the underlying photospheric magnetic elements. We will explain some of the difficulties in deriving the magnetic field vector from observations of the fluctosphere.

  7. Dynamically controlled energy dissipation for fast magnetic vortex switching

    Science.gov (United States)

    Badea, R.; Berezovsky, J.

    2017-09-01

    Manipulation of vortex states in magnetic media provides new routes towards information storage and processing technology. The typical slow relaxation times (˜100 ns) of magnetic vortex dynamics may present an obstacle to the realization of these applications. Here, we investigate how a vortex state in a ferromagnetic microdisk can be manipulated in a way that translates the vortex core while enhancing energy dissipation to rapidly damp the vortex dynamics. We use time-resolved differential magneto-optical Kerr effect microscopy to measure the motion of the vortex core in response to applied magnetic fields. We first map out how the vortex core becomes sequentially trapped by pinning sites as it translates across the disk. After applying a fast magnetic field step to translate the vortex from one pinning site to another, we observe long-lived dynamics of the vortex as it settles to the new equilibrium. We then demonstrate how the addition of a short (magnetic field pulse can induce additional energy dissipation, strongly damping the long-lived dynamics. A model of the vortex dynamics using the Thiele equation of motion explains the mechanism behind this effect.

  8. Semiclassical dynamics and magnetic Weyl calculus

    Energy Technology Data Exchange (ETDEWEB)

    Lein, Maximilian Stefan

    2011-01-19

    Weyl quantization and related semiclassical techniques can be used to study conduction properties of crystalline solids subjected to slowly-varying, external electromagnetic fields. The case where the external magnetic field is constant, is not covered by existing theory as proofs involving usual Weyl calculus break down. This is the regime of the so-called quantum Hall effect where quantization of transverse conductance is observed. To rigorously derive semiclassical equations of motion, one needs to systematically develop a magnetic Weyl calculus which contains a semiclassical parameter. Mathematically, the operators involved in the analysis are magnetic pseudodifferential operators, a topic which by itself is of interest for the mathematics and mathematical physics community alike. Hence, we will devote two additional chapters to further understanding of properties of those operators. (orig.)

  9. Lipoprotein subfractions by nuclear magnetic resonance are associated with tumor characteristics in breast cancer.

    Science.gov (United States)

    Flote, Vidar G; Vettukattil, Riyas; Bathen, Tone F; Egeland, Thore; McTiernan, Anne; Frydenberg, Hanne; Husøy, Anders; Finstad, Sissi E; Lømo, Jon; Garred, Øystein; Schlichting, Ellen; Wist, Erik A; Thune, Inger

    2016-03-12

    High-Density Lipoprotein (HDL)-cholesterol, has been associated with breast cancer development, but the association is under debate, and whether lipoprotein subfractions is associated with breast tumor characteristics remains unclear. Among 56 women with newly diagnosed invasive breast cancer stage I/II, aged 35-75 years, pre-surgery overnight fasting serum concentrations of lipids were assessed, and body mass index (BMI) was measured. All breast tumors were immunohistochemically examined in the surgical specimen. Serum metabolomics of lipoprotein subfractions and their contents of cholesterol, free cholesterol, phospholipids, apolipoprotein-A1 and apolipoprotein-A2, were assessed using nuclear magnetic resonance. Principal component analysis, partial least square analysis, and uni- and multivariable linear regression models were used to study whether lipoprotein subfractions were associated with breast cancer tumor characteristics. The breast cancer patients had following means: age at diagnosis: 55.1 years; BMI: 25.1 kg/m(2); total-Cholesterol: 5.74 mmol/L; HDL-Cholesterol: 1.78 mmol/L; Low-Density Lipoprotein (LDL)-Cholesterol: 3.45 mmol/L; triglycerides: 1.18 mmol/L. The mean tumor size was 16.4 mm, and the mean Ki67 hotspot index was 26.5%. Most (93%) of the patients had estrogen receptor (ER) positive tumors (≥ 1% ER+), and 82% had progesterone receptor (PgR) positive tumors (≥ 10% PgR+). Several HDL subfraction contents were strongly associated with PgR expression: Apolipoprotein-A1 (β 0.46, CI 0.22-0.69, p lipoproteins and ER expression. Our findings hypothesize associations between different lipoprotein subfractions, and PgR expression, and Ki 67 % in breast tumors. These findings may have clinical implications, but require confirmation in larger studies.

  10. Magnetic resonance imaging in patients with newly diagnosed breast cancer: a review of the literature.

    Science.gov (United States)

    Pilewskie, Melissa; King, Tari A

    2014-07-15

    The use of magnetic resonance imaging (MRI) in patients with newly diagnosed breast cancer remains controversial. Here we review the current use of breast MRI and the impact of MRI on short-term surgical outcomes and rates of local recurrence. In addition, we address the use of MRI in specific patient populations, such as those with ductal carcinoma in situ, invasive lobular carcinoma, and occult primary breast cancer, and discuss the potential role of MRI for assessing response to neoadjuvant chemotherapy. Although MRI has improved sensitivity compared with conventional imaging, this has not translated into improved short-term surgical outcomes or long-term patient benefit, such as improved local control or survival, in any patient population. MRI is an important diagnostic test in the evaluation of patients presenting with occult primary breast cancer and has shown promise in monitoring response to neoadjuvant chemotherapy; however, the data do not support the routine use of perioperative MRI in patients with newly diagnosed breast cancer. Cancer 2014;120:120:2080-2089. © 2014 American Cancer Society.

  11. Volumetric texture analysis of breast lesions on contrast-enhanced magnetic resonance images.

    Science.gov (United States)

    Chen, Weijie; Giger, Maryellen L; Li, Hui; Bick, Ulrich; Newstead, Gillian M

    2007-09-01

    Automated image analysis aims to extract relevant information from contrast-enhanced magnetic resonance images (CE-MRI) of the breast and improve the accuracy and consistency of image interpretation. In this work, we extend the traditional 2D gray-level co-occurrence matrix (GLCM) method to investigate a volumetric texture analysis approach and apply it for the characterization of breast MR lesions. Our database of breast MR images was obtained using a T1-weighted 3D spoiled gradient echo sequence and consists of 121 biopsy-proven lesions (77 malignant and 44 benign). A fuzzy c-means clustering (FCM) based method is employed to automatically segment 3D breast lesions on CE-MR images. For each 3D lesion, a nondirectional GLCM is then computed on the first postcontrast frame by summing 13 directional GLCMs. Texture features are extracted from the nondirectional GLCMs and the performance of each texture feature in the task of distinguishing between malignant and benign breast lesions is assessed by receiver operating characteristics (ROC) analysis. Our results show that the classification performance of volumetric texture features is significantly better than that based on 2D analysis. Our investigations of the effects of various of parameters on the diagnostic accuracy provided means for the optimal use of the approach.

  12. Evaluation of expert criteria for preoperative magnetic resonance imaging of newly diagnosed breast cancer.

    Science.gov (United States)

    Behrendt, Carolyn E; Tumyan, Lusine; Gonser, Laura; Shaw, Sara L; Vora, Lalit; Paz, I Benjamin; Ellenhorn, Joshua D I; Yim, John H

    2014-08-01

    Despite 2 randomized trials reporting no reduction in operations or local recurrence at 1 year, preoperative magnetic resonance imaging (MRI) is increasingly used in diagnostic workup of breast cancer. We evaluated 5 utilization criteria recently proposed by experts. Of women (n = 340) newly diagnosed with unilateral breast cancer who underwent bilateral MRI, most (69.4%) met at least 1 criterion before MRI: mammographic density (44.4%), under consideration for partial breast irradiation (PBI) (19.7%), genetic-familial risk (12.9%), invasive lobular carcinoma (11.8%), and multifocal/multicentric disease (10.6%). MRI detected occult malignant lesion or extension of index lesion in 21.2% of index, 3.3% of contralateral, breasts. No expert criterion was associated with MRI-detected malignant lesion, which associated instead with pre-MRI plan of lumpectomy without PBI (48.2% of subjects): Odds Ratio 3.05, 95% CI 1.57-5.91 (p adjusted for multiple hypothesis testing = 0.007, adjusted for index-vs-contralateral breast and covariates). The expert guidelines were not confirmed by clinical evidence.

  13. Magnetic resonance imaging in the evaluation of breast cancer; O uso da ressonancia magnetica na investigacao do cancer mamario

    Energy Technology Data Exchange (ETDEWEB)

    Alvares, Beatriz Regina [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Ciencias Medicas. Dept. de Radiologia]. E-mail: alvaresb@terra.com.br; Michell, Michael [King' s College Hospital, London (United Kingdom). Dept. of Radiology and Nuclear Medicine

    2003-12-01

    Mammography, ultrasonography and scintimammography are essential examinations for the diagnosis and post-surgical follow-up of patients with breast cancer, although all these modalities may present specific limitations. In recent years magnetic resonance imaging has demonstrated good performance in detecting breast tumors in the mammary gland. In this study the authors describe the magnetic resonance imaging main indications and findings in patients with breast cancer, and compare the performance of mammography, ultrasonography and scintimammography, including the advantages and limitations of each modality. (author)

  14. Ultrafast magnetization dynamics of lanthanide metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sultan, Muhammad

    2012-05-14

    In this study, the laser-induced magnetization dynamics of the lanthanide ferromagnets Gadolinium (Gd), Terbium (Tb) and their alloys is investigated using femtosecond (fs) time-resolved x-ray magnetic circular dichroism (XMCD), the magneto-optical Kerr effect (MOKE) and magnetic second harmonic generation (MSHG). The magnetization dynamics is analyzed from the time scale of a few fs up to several hundred picoseconds (ps). The contributions of electrons, phonons, spin fluctuations, as well as the temporal regimes corresponding to the spin-orbit and exchange interactions are disentangled. In addition to possible applications in magnetic storage devices, understanding magnetization dynamics in lanthanides is also important because of their different magnetic structure compared to well-studied itinerant ferromagnets. Lanthanides are model Heisenberg-ferromagnets with localized 4f magnetic moments and long range magnetic ordering through indirect exchange interaction. By optical excitation of the conduction electrons, which mediate the exchange interaction, and studying the induced dynamics of the localized 4f and delocalized 5d6s magnetic moments, one can obtain insight into the angular momentum transfer at ultrafast time scales. Moreover, lanthanides offer the possibility to tune spin-lattice coupling via the 4f shell occupation and the concomitant changes in the 4f spin and orbital moments due to Hund's rules. Utilizing this fact, the importance of spin-lattice coupling in laser-induced demagnetization is also analyzed by comparing the magnetization dynamics in Gd and Tb. By investigating the magnetization dynamics of localized 4f moments of Gd and Tb using time-resolved XMCD, it is found that the demagnetization proceeds in both metals in two time scales, following fs laser excitation, which are classified as: (i) non-equilibrium (t > 1 ps), with respect to equilibration of electron and phonon temperatures. The

  15. Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig

    Science.gov (United States)

    Morrison, Carlos R.; Provenza, Andrew; Kurkov, Anatole; Mehmed, Oral; Johnson, Dexter; Montague, Gerald; Duffy, Kirsten; Jansen, Ralph

    2005-01-01

    The Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig is an apparatus for vibration testing of turbomachine blades in a vacuum at rotational speeds from 0 to 40,000 rpm. This rig includes (1) a vertically oriented shaft on which is mounted an assembly comprising a rotor holding the blades to be tested, (2) two actively controlled heteropolar radial magnetic bearings at opposite ends of the shaft, and (3) an actively controlled magnetic thrust bearing at the upper end of the shaft. This rig is a more capable successor to a prior apparatus, denoted the Dynamic Spin Rig (DSR), that included a vertically oriented shaft with a mechanical thrust bearing at the upper end and a single actively controlled heteropolar radial magnetic bearing at the lower end.

  16. Dynamics of molecular superrotors in external magnetic field

    CERN Document Server

    Korobenko, Aleksey

    2015-01-01

    We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to the qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin-rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane in three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation.

  17. Field-driven magnetization dynamics of nanoparticles and nanowires

    Science.gov (United States)

    Lu, Jie

    This thesis is about micromagnetism in confined magnetic microstructures. The field-driven magnetization dynamics of nanoparticles and nanowires is systematically discussed following a clear thread of thought: from "macrospin" to "microspin". At the same time, four topics are raised and investigated. First, inspired by the traditional ferromagnetic resonance technique, two strategies for measuring the Gilbert damping coefficient using the magnetic circular dichroism effect are presented and discussed. The investigation is performed within a framework of the linear response of the macrospin in 2-D magnetic films to external time-dependent fields. The object of the study then turns to Stoner particles, which are single-domain magnetic nanoparticles, that are quasi 0-D systems and still assumed to be macrospins. The field-driven magnetization reversal in multi-axial Stoner particles is investigated and the corresponding Eular equations are presented. The Eular equations provide a unified framework for research of this kind. After that, the macrospin assumption itself is examined. The study of when and how it fails results in the famous "nucleation problem" in micromagnetism, thus the discussion then moves into the microspin category. The nucleation problem of single-domain cuboid permalloy nanowires, which are quasi 1-D systems, is investigated and a magnetization reversal mode named "domain formation and domain wall propagation" is revealed. Field-driven magnetic domain wall propagation is an excellent example of microspin behavior, and has been a hot issue in recent spintronic research. The effects of transverse magnetic anisotropies on field-driven transverse wall propagation in narrow magnetic nanowires are systematically investigated. These results should not only deepen the understanding of the domain wall dynamics in magnetic nanowires, but also offer inspiration for further developments of ultrafast nano-devices with higher integration levels.

  18. Association between dynamic features of breast DCE-MR imaging and clinical response of neoadjuvant chemotherapy: a preliminary analysis

    Science.gov (United States)

    Huang, Lijuan; Fan, Ming; Li, Lihua; Zhang, Juan; Shao, Guoliang; Zheng, Bin

    2016-03-01

    Neoadjuvant chemotherapy (NACT) is being used increasingly in the management of patients with breast cancer for systemically reducing the size of primary tumor before surgery in order to improve survival. The clinical response of patients to NACT is correlated with reduced or abolished of their primary tumor, which is important for treatment in the next stage. Recently, the dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is used for evaluation of the response of patients to NACT. To measure this correlation, we extracted the dynamic features from the DCE- MRI and performed association analysis between these features and the clinical response to NACT. In this study, 59 patients are screened before NATC, of which 47 are complete or partial response, and 12 are no response. We segmented the breast areas depicted on each MR image by a computer-aided diagnosis (CAD) scheme, registered images acquired from the sequential MR image scan series, and calculated eighteen features extracted from DCE-MRI. We performed SVM with the 18 features for classification between patients of response and no response. Furthermore, 6 of the 18 features are selected to refine the classification by using Genetic Algorithm. The accuracy, sensitivity and specificity are 87%, 95.74% and 50%, respectively. The calculated area under a receiver operating characteristic (ROC) curve is 0.79+/-0.04. This study indicates that the features of DCE-MRI of breast cancer are associated with the response of NACT. Therefore, our method could be helpful for evaluation of NACT in treatment of breast cancer.

  19. Solar dynamics and magnetism from the interior to the atmosphere

    CERN Document Server

    Kosovichev, Alexander; Komm, Rudolf; Longcope, Dana

    2014-01-01

    NASA's Solar Dynamics Observatory (SDO) mission has provided a large amount of new data on solar dynamics and magnetic activities during the rising phase of the current and highly unusual solar cycle. These data are complemented by the continuing SOHO mission, and by ground-based observatories that include the GONG helioseismology network and the New Solar Telescope. Also, the observations are supported by realistic numerical simulations on supercomputers. This unprecedented amount of data provides a unique opportunity for multi-instrument investigations that address fundamental problems of the origin of solar magnetic activity at various spatial and temporal scales. This book demonstrates that the synergy of high-resolution multi-wavelength observations and simulations is a key to uncovering the long-standing puzzles of solar magnetism and dynamics. This volume is aimed at researchers and graduate students active in solar physics and space science. Previously published in Solar Physics journal, Vol. 287/1-2,...

  20. Optimal control of stochastic magnetization dynamics by spin current

    Science.gov (United States)

    Wang, Yong; Zhang, Fu-Chun

    2013-05-01

    Fluctuation-induced stochastic magnetization dynamics plays an important role in spintronics devices. Here we propose that it can be optimally controlled by spin currents to minimize or maximize the Freidlin-Wentzell action functional of the system hence to increase or decrease the probability of the large fluctuations. We apply this method to study the thermally activated magnetization switching problem and to demonstrate the merits of the optimal control strategy.

  1. Dynamical localization: Hydrogen atoms in magnetic and microwave fields

    Energy Technology Data Exchange (ETDEWEB)

    Benvenuto, F.; Casati, G. [Dipartimento di Fisica dellUniversita, Via Castelnuovo 7, 22100 Como (Italy); Shepelyansky, D.L. [Laboratoire de Physique Quantique, UMR C5626 du CNRS, Universite Paul Sabatier, 31062, Toulouse (France)

    1997-03-01

    We show that dynamical localization for excited hydrogen atoms in magnetic and microwave fields takes place at quite low microwave frequency ({omega}n{sup 3}{lt}1). Estimates of the localization length are given for different parameter regimes, showing that the quantum delocalization border drops significantly as compared to the case of zero magnetic field. This opens up broad possibilities for laboratory investigations. {copyright} {ital 1997} {ital The American Physical Society}

  2. Breast fibromatosis response to tamoxifen: dynamic MRI findings and review of the current treatment options.

    Science.gov (United States)

    Plaza, Michael J; Yepes, Monica

    2012-03-01

    Breast fibromatosis is a rare entity responsible for 0.2% of all solid breast tumors. It has been associated with scars, pregnancy, implants, and familial adenomatous polyposis. We present an interesting case of breast fibromatosis in a 29 year old woman which encroached upon her saline implant and subsequently filled its cavity once the implant was removed. The patient was put on tamoxifen therapy and at 14 month follow-up there was a significant decrease in the size of the mass. Dynamic MRI images are offered for review and current treatment options are discussed.

  3. Intravoxel incoherent motion MR imaging for breast lesions: comparison and correlation with pharmacokinetic evaluation from dynamic contrast-enhanced MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chunling; Liu, Zaiyi; Zhang, Jine; He, Hui; Zhang, Shuixing; Liang, Changhong [Guangdong General Hospital/Guangdong Academy of Medical Sciences, Department of Radiology, GuangZhou (China); Wang, Kun [Guangdong General Hospital/Guangdong Academy of Medical Sciences, Department of Breast Cancer, Cancer Center, GuangZhou (China); Chan, Queenie [Philips Healthcare, 6/F, Core Building 1, 1 Science Park East Avenue, Hong Kong Science Park, Shatin, New Territories, Hong Kong (China)

    2016-11-15

    To compare diagnostic performance for breast lesions by quantitative parameters derived from intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and to explore whether correlations exist between these parameters. IVIM and DCE MRI were performed on a 1.5-T MRI scanner in patients with suspicious breast lesions. Thirty-six breast cancers and 23 benign lesions were included in the study. Quantitative parameters from IVIM (D, f and D*) and DCE MRI (K{sup trans}, K{sub ep}, V{sub e} and V{sub p}) were calculated and compared between malignant and benign lesions. Spearman correlation test was used to evaluate correlations between them. D, f, D* from IVIM and K{sup trans}, K{sub ep}, V{sub p} from DCE MRI were statistically different between breast cancers and benign lesions (p < 0.05, respectively) and D demonstrated the largest area under the receiver-operating characteristic curve (AUC = 0.917) and had the highest specificity (83 %). The f value was moderately statistically correlated with V{sub p} (r = 0.692) and had a poor correlation with K{sup trans} (r = 0.456). IVIM MRI is useful in the differentiation of breast lesions. Significant correlations were found between perfusion-related parameters from IVIM and DCE MRI. IVIM may be a useful adjunctive tool to standard MRI in diagnosing breast cancer. (orig.)

  4. Magnetic tunnel junctions using perpendicularly magnetized synthetic antiferromagnetic reference layer for wide-dynamic-range magnetic sensors

    Science.gov (United States)

    Nakano, T.; Oogane, M.; Furuichi, T.; Ando, Y.

    2017-01-01

    We developed CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) with a perpendicularly magnetized synthetic antiferromagnetic (p-SAF) reference layer for magnetic sensor applications. The MTJs exhibited linear tunnel magnetoresistance curves to out-of-plane applied magnetic fields with dynamic ranges more than ±2.5 kOe, which are wider than those in CoFeB/MgO/CoFeB-MTJs reported to date. The performance metrics of MTJ sensors, i.e., sensitivity and nonlinearity, depend significantly on the anisotropy field of the free layer. We explained the dependences by a simple model based on the Stoner-Wohlfarth and Slonczewski models, which gives us a guideline to design the sensor performance metrics. These findings demonstrated that MTJs with a p-SAF reference layer are promising candidates for wide-dynamic-range magnetic sensors.

  5. Interplay of domain walls and magnetization rotation on dynamic magnetization process in iron/polymer-matrix soft magnetic composites

    Science.gov (United States)

    Dobák, Samuel; Füzer, Ján; Kollár, Peter; Fáberová, Mária; Bureš, Radovan

    2017-03-01

    This study sheds light on the dynamic magnetization process in iron/resin soft magnetic composites from the viewpoint of quantitative decomposition of their complex permeability spectra into the viscous domain wall motion and magnetization rotation. We present a comprehensive view on this phenomenon over the broad family of samples with different average particles dimension and dielectric matrix content. The results reveal the pure relaxation nature of magnetization processes without observation of spin resonance. The smaller particles and higher amount of insulating resin result in the prevalence of rotations over domain wall movement. The findings are elucidated in terms of demagnetizing effects rising from the heterogeneity of composite materials.

  6. Berry curvature and dynamics of a magnetic bubble

    Science.gov (United States)

    Koshibae, Wataru; Nagaosa, Naoto

    2016-04-01

    Magnetic bubbles have been the subject of intensive studies aiming to investigate their applications to memory devices. A bubble can be regarded as the closed domain wall and is characterized by the winding number of the in-plane components or the skyrmion number N sk , which are related to the number of Bloch lines (BLs). For the magnetic bubbles without BLs, the Thiele equation assuming no internal distortion describes the center-of-mass motion of the bubbles very well. For the magnetic bubbles with BLs, on the other hand, their dynamics is affected seriously by that of BLs along the domain wall. Here we show theoretically, that the distribution of the Berry curvature b z , i.e., the solid angle formed by the magnetization vectors, in the bubble plays the key role in the dynamics of a bubble with {N}{sk}=0 in a dipolar magnet. In this case, the integral of b z over the space is zero, while the nonuniform distribution of b z and associated Magnus force induce several nontrivial coupled dynamics of the internal deformation and center-of-mass motion as explicitly demonstrated by numerical simulations of Landau-Lifshitz-Gilbert equation. These findings give an alternative view and will pave a new route to design the bubble dynamics.

  7. Dynamics of magnetic nanoparticles in a viscous fluid driven by rotating magnetic fields

    Science.gov (United States)

    Usadel, Klaus D.

    2017-03-01

    The rotational dynamics of magnetic nanoparticles in rotating magnetic fields in the presence of thermal noise is studied both theoretically and by performing numerical calculations. Equations for the dynamics of particles with uniaxial magnetic anisotropy are studied and the phase lag between the rotating magnetic moment and the driving field is obtained. It is shown that for large enough anisotropy energy the magnetic moment is locked to the anisotropy axis so that the particle behaves like a rotating magnetic dipole. The corresponding rigid dipole model is analyzed both numerically by solving the appropriate Fokker-Planck equation and analytically by applying an effective field method. In the special case of a rotating magnetic field applied analytic results are obtained in perfect agreement with numerical results based on the Fokker-Planck equation. The analytic formulas derived are not restricted to small magnetic fields or low frequencies and are therefore important for applications. The illustrative numerical calculations presented are performed for magnetic parameters typical for iron oxide.

  8. Magnetic resonance imaging for monitoring the effects of thalidomide on experimental human breast cancers

    Energy Technology Data Exchange (ETDEWEB)

    Cyran, Clemens C. [University of California San Francisco, Center for Pharmaceutical and Molecular Imaging, Department of Radiology, San Francisco, CA (United States); Ludwig-Maximilians-University, Department of Clinical Radiology, Klinikum Grosshadern, Munich (Germany); Sennino, Barbara; McDonald, Donald M. [University of California San Francisco, Comprehensive Cancer Center, Cardiovascular Research Institute, and Department of Anatomy, San Francisco, CA (United States); Chaopathomkul, Bundit; Fu, Yanjun; Rogut, Victor S.; Shames, David M.; Wendland, Michael F.; Brasch, Robert C. [University of California San Francisco, Center for Pharmaceutical and Molecular Imaging, Department of Radiology, San Francisco, CA (United States)

    2009-01-15

    Thalidomide, which inhibits angiogenesis in certain tumor types, reduced extravasation of a macromolecular contrast medium (MMCM) in a human breast cancer model as assayed by MMCM-enhanced dynamic magnetic resonance imaging (MRI) and fluorescence microscopy in the same tumors. After a 1-week, three-dose course of thalidomide, the mean MRI-assayed endothelial transfer coefficient, K{sup PS}, decreased significantly (p<0.05) from 19.4{+-}9.1 to 6.3{+-}9.1 {mu}l/min.100 cm{sup 3}. Correspondingly, microscopic measurements of extravasated MMCM, expressed as fractional area of streptavidin staining, were significantly (p<0.05) lower in thalidomide-treated tumors (18.6{+-}11.9%) than in control saline-treated tumors (50.2{+-}2.3%). On a tumor-by-tumor basis, post-treatment K{sup PS} values correlated significantly (r{sup 2}=0.55, p<0.05) with microscopic measures of MMCM extravasation. However, no significant differences were observed between saline- and thalidomide-treated tumors with respect to rate of growth, vascular richness, or amount of VEGF-containing cells. Because of its sensitivity to the detection of changes in vascular leakage in tumors, this MMCM-enhanced MRI assay could prove useful for monitoring the effects of thalidomide on an individual patient basis. The significant correlation between MRI and fluorescence microscopic measures of MMCM extravasation supports the utility of the non-invasive MRI approach for assessing the action of thalidomide on tumor blood vessels. (orig.)

  9. Vertically polarizing undulator with dynamic compensation of magnetic forces

    Science.gov (United States)

    Strelnikov, N.; Vasserman, I.; Xu, J.; Jensen, D.; Schmidt, O.; Trakhtenberg, E.; Suthar, K.; Moog, E. R.; Pile, G.; Gluskin, E.

    2017-01-01

    As part of the R&D program of the LCLS-II project, a novel 3.4-meter-long undulator prototype with horizontal magnetic field and dynamic force compensation has recently been developed at the Advanced Photon Source (APS). Previous steps in this development were the shorter 0.8-meter-long and 2.8-meter-long prototypes. Extensive mechanical and magnetic testing were carried out for each prototype, and each prototype was magnetically tuned using magnetic shims. The resulting performance of the 3.4-meter-long undulator prototype meets all requirements for the LCLS-II insertion device, including limits on the field integrals, phase errors, higher-order magnetic moments, and electron-beam trajectory for all operational gaps, as well as the reproducibility and accuracy of the gap settings.

  10. Vertically Polarizing Undulator with Dynamic Compensation of Magnetic Forces

    Energy Technology Data Exchange (ETDEWEB)

    Strelnikov, N.; Vasserman, I.; Xu, J.; Jensen, D.; Schmidt, O.; Trakhtenberg, E.; Suthar, K.; Moog, E. R.; Pile, G.; Gluskin, E.

    2017-01-20

    As part of the R&D program of the LCLS-II project, a novel 3.4-meter-long undulator prototype with horizontal magnetic field and dynamic force compensation has recently been developed at the Advanced Photon Source (APS). Previous steps in this development were the shorter 0.8-meter-long and 2.8-meter-long prototypes. Extensive mechanical and magnetic testing was carried out for each prototype, and each prototype was magnetically tuned using magnetic shims. The resulting performance of the 3.4-meter-long undulator prototype meets all requirements for the LCLS-II insertion device, including limits on the field integrals, phase errors, higher-order magnetic moments, and electron-beam trajectory for all operational gaps, as well as the reproducibility and accuracy of the gap settings.

  11. Dynamics of whistler spheromaks in magnetized plasmas.

    Science.gov (United States)

    Eliasson, B; Shukla, P K

    2007-11-16

    Recent laboratory experiments [Stenzel et al., Phys. Rev. Lett. 96, 095004 (2006)10.1103/PhysRevLett.96.095004] have demonstrated interesting phenomena of propagating nonlinear whistler structures (spheromaks) and stationary field-reversed configurations, whose magnetic fields exceed the ambient magnetic field strength. Our objective here is to present simulation studies for these nonlinear whistler structures based on the three-dimensional nonlinear electron magnetohydrodynamic equations. The robustness and longevity of the propagating whistler spheromaks found in the experiments are confirmed numerically. Varying the toroidal field of the spheromak in the initial conditions, we find that the polarity and the amplitude of the toroidal field determine the propagation direction and speed of the spheromak. Our simulation results are in excellent agreement with those observed in the laboratory experiments.

  12. Global dynamics of dust grains in magnetic planets

    Energy Technology Data Exchange (ETDEWEB)

    Inarrea, Manuel [Universidad de La Rioja, Area de Fisica Aplicada, 26006 Logrono (Spain)]. E-mail: manuel.inarrea@dq.unirioja.es; Lanchares, Victor [Universidad de La Rioja, Departamento de Matematicas y Computacion, 26004 Logrono (Spain); Palacian, Jesus F. [Universidad Publica de Navarra, Departamento de Matematica e Informatica, 31006 Pamplona (Spain); Pascual, Ana I. [Universidad de La Rioja, Departamento de Matematicas y Computacion, 26004 Logrono (Spain); Salas, J. Pablo [Universidad de La Rioja, Area de Fisica Aplicada, 26006 Logrono (Spain); Yanguas, Patricia [Universidad Publica de Navarra, Departamento de Matematica e Informatica, 31006 Pamplona (Spain)

    2005-05-02

    We study the dynamics of a charged particle orbiting a rotating magnetic planet. The system is modelled by the Hamiltonian of the two-body problem perturbed by an axially-symmetric potential. The perturbation consists in a magnetic dipole field and a corotational electric field. After an averaging process we arrive at a one degree of freedom Hamiltonian system for which we obtain its relative equilibria and bifurcations. It is shown that the system exhibits a complex and rich dynamics. In particular, dramatic changes in the phase flow take place in the vicinity of a circular equatorial orbit, that in the case of Saturn is located inside the E-ring.

  13. Catalysis of dynamical symmetry breaking by a magnetic field

    CERN Document Server

    Miransky, V A

    1995-01-01

    A constant magnetic field in 3+1 and 2+1 dimensions is a strong catalyst of dynamical chiral symmetry breaking, leading to the generation of a fermion mass even at the weakest attractive interaction between fermions. The essence of this effect is the dimensional reduction D/rightarrow D-2 in the dynamics of fermion pairing in a magnetic field. The effect is illustrated in the Nambu-Jona-Lasinio model and QED. Possible applications of this effect and its extension to inhomogeneous field configurations are discussed.

  14. Dynamic magnetic hysteresis and nonlinear susceptibility of antiferromagnetic nanoparticles

    Science.gov (United States)

    Kalmykov, Yuri P.; Ouari, Bachir; Titov, Serguey V.

    2016-08-01

    The nonlinear ac stationary response of antiferromagnetic nanoparticles subjected to both external ac and dc fields of arbitrary strength and orientation is investigated using Brown's continuous diffusion model. The nonlinear complex susceptibility and dynamic magnetic hysteresis (DMH) loops of an individual antiferromagnetic nanoparticle are evaluated and compared with the linear regime for extensive ranges of the anisotropy, the ac and dc magnetic fields, damping, and the specific antiferromagnetic parameter. It is shown that the shape and area of the DMH loops of antiferromagnetic particles are substantially altered by applying a dc field that permits tuning of the specific magnetic power loss in the nanoparticles.

  15. Dynamic analysis of magnetic nanoparticles crossing cell membrane

    Science.gov (United States)

    Pedram, Maysam Z.; Shamloo, Amir; Ghafar-Zadeh, Ebrahim; Alasty, Aria

    2017-01-01

    Nowadays, nanoparticles (NPs) are used in a variety of biomedical applications including brain disease diagnostics and subsequent treatments. Among the various types of NPs, magnetic nanoparticles (MNPs) have been implemented by many research groups for an array of life science applications. In this paper, we studied MNPs controlled delivery into the endothelial cells using a magnetic field. Dynamics equations of MNPs were defined in the continuous domain using control theory methods and were applied to crossing the cell membrane. This study, dedicated to clinical and biomedical research applications, offers a guideline for the generation of a magnetic field required for the delivery of MNPs.

  16. Dynamic Accuracy of Inertial Magnetic Sensor Modules

    Science.gov (United States)

    2016-12-01

    interpolate function to replace the repeating values to ensure the RMS value was only calculated with the ground truth data obtained directly from...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) Magnetic, angular rate, and gravity (MARG) sensor modules have extensive applications in inertial...and gravity , MARG, micro-electro-mechanical systems, MEMS, quaternion 15. NUMBER OF PAGES 147 16. PRICE CODE 17. SECURITY CLASSIFICATION OF

  17. Monitoring the Earth's Dynamic Magnetic Field

    Science.gov (United States)

    Love, Jeffrey J.; Applegate, David; Townshend, John B.

    2008-01-01

    The mission of the U.S. Geological Survey's Geomagnetism Program is to monitor the Earth's magnetic field. Using ground-based observatories, the Program provides continuous records of magnetic field variations covering long timescales; disseminates magnetic data to various governmental, academic, and private institutions; and conducts research into the nature of geomagnetic variations for purposes of scientific understanding and hazard mitigation. The program is an integral part of the U.S. Government's National Space Weather Program (NSWP), which also includes programs in the National Aeronautics and Space Administration (NASA), the Department of Defense (DOD), the National Oceanic and Atmospheric Administration (NOAA), and the National Science Foundation (NSF). The NSWP works to provide timely, accurate, and reliable space weather warnings, observations, specifications, and forecasts, and its work is important for the U.S. economy and national security. Please visit the National Geomagnetism Program?s website, http://geomag.usgs.gov, where you can learn more about the Program and the science of geomagnetism. You can find additional related information at the Intermagnet website, http://www.intermagnet.org.

  18. Spin kinetic Monte Carlo method for nanoferromagnetism and magnetization dynamics of nanomagnets with large magnetic anisotropy

    Institute of Scientific and Technical Information of China (English)

    LIU Bang-gui; ZHANG Kai-cheng; LI Ying

    2007-01-01

    The Kinetic Monte Carlo (KMC) method based on the transition-state theory, powerful and famous for sim-ulating atomic epitaxial growth of thin films and nanostruc-tures, was used recently to simulate the nanoferromagnetism and magnetization dynamics of nanomagnets with giant mag-netic anisotropy. We present a brief introduction to the KMC method and show how to reformulate it for nanoscale spin systems. Large enough magnetic anisotropy, observed exper-imentally and shown theoretically in terms of first-principle calculation, is not only essential to stabilize spin orientation but also necessary in making the transition-state barriers dur-ing spin reversals for spin KMC simulation. We show two applications of the spin KMC method to monatomic spin chains and spin-polarized-current controlled composite nano-magnets with giant magnetic anisotropy. This spin KMC method can be applied to other anisotropic nanomagnets and composite nanomagnets as long as their magnetic anisotropy energies are large enough.

  19. Static and dynamic critical behavior of thin magnetic Ising films

    Science.gov (United States)

    Sabogal-Suárez, D.; Alzate-Cardona, J. D.; Restrepo-Parra, E.

    2015-09-01

    This work presents a study of the effect of film thickness on the static and dynamic critical behavior of thin magnetic Ising films. Monte Carlo simulations using the Wolff algorithm were performed to determine the static and dynamic critical exponents of the films. A dimensionality crossover from 2D to 3D (due to the finiteness of the films) in the static and dynamic critical behavior was observed as the film thickness increases. In addition, a slight increase in the effective dimension deff and a considerable increase in the critical temperature Tc(∞) were found. Small values for the dynamic critical exponents were obtained, indicating that the Wolff algorithm is a very efficient method for these magnetic systems.

  20. Experimental treatment of breast cancer-bearing BALB/c mice by artemisinin and transferrin-loaded magnetic nanoliposomes.

    Science.gov (United States)

    Gharib, Amir; Faezizadeh, Zohreh; Mesbah-Namin, Seyed Ali Reza; Saravani, Ramin

    2015-05-01

    The combination of artemisinin and transferrin exhibits versatile anticancer activities. In previous, we successfully prepared artemisinin and transferrin-loaded magnetic nanoliposomes and evaluated their anti-proliferative activity against MCF-7 and MDA-MB-231 cell lines in vitro. In this study, we investigate the in vivo anti-breast cancer activity of artemisinin and transferrin-loaded magnetic nanoliposome against breast transplanted tumors in BALB/c mice model. Artemisinin and transferrin-loaded magnetic nanoliposomes were prepared and characterized for some physiochemical properties. Pieces of tumor tissue from the breast cancer-bearing BALB/c mice were transplanted subcutaneously to the syngeneic female BALB/c mice. In the presence of the external magnet that placed at the breast tumor site, the tissue distribution and tumor-suppressing effects of prepared nanoliposomes on tumor growth was evaluated. The prepared nanoliposomes have fine spherical shape, rough surface, nano-sized diameter and magnetic properties. At 2 h after treatment, the intravenous administration of artemisinin and transferrin-loaded magnetic nanoliposomes followed using the magnetic field approximately produced 10- and 5.5-fold higher levels of artemisinin and transferrin in the tumors, respectively, compared with free artemisinin and transferrin. Moreover, in the presence of an external magnetic field, the prepared nanoliposomes could significantly induce apoptosis in the mice breast cancer cells as well as could reduce tumor volume in tumorized mice at 15 days after treatment. The data suggested that the artemisinin and transferrin-loaded magnetic nanoliposomes would be a good choice for the breast tumor-targeted therapy, due to its high targeting efficiency.

  1. The contralateral synchronous breast carcinoma: a comparison of histology, localization, and magnetic resonance imaging characteristics with the primary index cancer.

    Science.gov (United States)

    Renz, Diane M; Böttcher, Joachim; Baltzer, Pascal A T; Dietzel, Matthias; Vag, Tibor; Gajda, Mieczyslaw; Camara, Oumar; Runnebaum, Ingo B; Kaiser, Werner A

    2010-04-01

    Women with unilateral breast carcinoma reveal an increased risk of suffering from malignancies in the contralateral breast. There is a controversy about the existence of bilateral phenotypic similarities. The aim of this investigation was to compare histologic findings, magnetic resonance imaging (MRI) parameters, and tumor localizations of synchronous bilateral carcinomas. MRI revealed in 42 of 875 women (4.8%) with primary index carcinomas a contralateral malignancy. Twenty-two of the 42 contralateral carcinomas could only be detected by MRI, not by clinical examination, X-ray mammography, or ultrasonography. In 875 patients, MRI therefore identified 22 (2.5%) otherwise occult contralateral cancers. To evaluate bilateral MRI similarities, multiple dynamic and morphologic parameters were evaluated. Of 42 bilateral cancer pairs, histologic tumor type was identical in 54.8% (correlation analysis, P types were bilaterally congruent on MRI (P analogies of tumor neoangiogenesis, histopathologic components, and infiltration in the surrounding stroma. Bilateral synchronous carcinomas may represent on each site distinct, but similar biologic entities, due to analogous influences of tumor developments.

  2. Breast MRI scan

    Science.gov (United States)

    MRI - breast; Magnetic resonance imaging - breast; Breast cancer - MRI; Breast cancer screening - MRI ... radiologist) see some areas more clearly. During the MRI, the person who operates the machine will watch ...

  3. Comparison of breast tissue measurements using magnetic resonance imaging, digital mammography and a mathematical algorithm

    Science.gov (United States)

    Lu, Lee-Jane W.; Nishino, Thomas K.; Johnson, Raleigh F.; Nayeem, Fatima; Brunder, Donald G.; Ju, Hyunsu; Leonard, Morton H., Jr.; Grady, James J.; Khamapirad, Tuenchit

    2012-11-01

    Women with mostly mammographically dense fibroglandular tissue (breast density, BD) have a four- to six-fold increased risk for breast cancer compared to women with little BD. BD is most frequently estimated from two-dimensional (2D) views of mammograms by a histogram segmentation approach (HSM) and more recently by a mathematical algorithm consisting of mammographic imaging parameters (MATH). Two non-invasive clinical magnetic resonance imaging (MRI) protocols: 3D gradient-echo (3DGRE) and short tau inversion recovery (STIR) were modified for 3D volumetric reconstruction of the breast for measuring fatty and fibroglandular tissue volumes by a Gaussian-distribution curve-fitting algorithm. Replicate breast exams (N = 2 to 7 replicates in six women) by 3DGRE and STIR were highly reproducible for all tissue-volume estimates (coefficients of variation tissue, (2) 0.72-0.82, 0.64-0.96, and 0.77-0.91, for glandular volume, (3) 0.87-0.98, 0.94-1.07, and 0.89-0.99, for fat volume, and (4) 0.89-0.98, 0.94-1.00, and 0.89-0.98, for total breast volume. For all values estimated, the correlation was stronger for comparisons between the two MRI than between each MRI versus mammography, and between each MRI versus MATH data than between each MRI versus HSM data. All ICC values were >0.75 indicating that all four methods were reliable for measuring BD and that the mathematical algorithm and the two complimentary non-invasive MRI protocols could objectively and reliably estimate different types of breast tissues.

  4. Magnetic Nanostructures Spin Dynamics and Spin Transport

    CERN Document Server

    Farle, Michael

    2013-01-01

    Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.

  5. Dynamic characterization for tumor- and deformation-induced thermal contrasts on breast surface: a simulation study

    Science.gov (United States)

    Jiang, Li; Zhan, Wang; Loew, Murray H.

    2009-02-01

    Understanding the complex relationship between the thermal contrasts on the breast surface and the underlying physiological and pathological factors is important for thermogram-based breast cancer detection. Our previous work introduced a combined thermal-elastic modeling method with improved ability to simultaneously characterize both elastic-deformation-induced and tumor-induced thermal contrasts on the breast. In this paper, the technique is further extended to investigate the dynamic behaviors of the breast thermal contrasts during cold stress and thermal recovery procedures in the practice of dynamic thermal imaging. A finite-element method (FEM) has been developed for dynamic thermal and elastic modeling. It is combined with a technique to address the nonlinear elasticity of breast tissues, as would arise in the large deformations caused by gravity. Our simulation results indicate that different sources of the thermal contrasts, such as the presence of a tumor, and elastic deformation, have different transient time courses in dynamic thermal imaging with cold-stress and thermal-recovery. Using appropriate quantifications of the thermal contrasts, we find that the tumor- and deformation-induced thermal contrasts show opposite changes in the initial period of the dynamic courses, whereas the global maxima of the contrast curves are reached at different time points during a cold-stress or thermal-recovery procedure. Moreover, deeper tumors generally lead to smaller peaks but have larger lags in the thermal contrast time course. These findings suggest that dynamic thermal imaging could be useful to differentiate the sources of the thermal contrast on breast surface and hence to enhance tumor detectability.

  6. Spin dynamics in highly frustrated pyrochlore magnets

    Science.gov (United States)

    Petit, Sylvain; Guitteny, Solène; Robert, Julien; Bonville, Pierre; Decorse, Claudia; Ollivier, Jacques; Mutka, Hannu; Mirebeau, Isabelle

    2015-01-01

    This paper aims at showing the complementarity between time-of-flight and triple-axis neutron scattering experiments, on the basis of two topical examples in the field of geometrical magnetic frustration. Rare earth pyrochlore magnets R2Ti2O7 (R is a rare earth) play a prominent role in this field, as they form model systems showing a rich variety of ground states, depending on the balance between dipolar, exchange interactions and crystal field. We first review the case of the XY antiferromagnet Er2 Ti2 O7. Here a transition towards a Néel state is observed, possibly induced by an order-by-disorder mechanism. Effective exchange parameters can be extracted from S(Q,ω). We then examine the case of the spin liquid Tb2 Ti2 O7. Recent experiments reveal a complex ground state characterized by "pinch points" and supporting a low energy excitation. These studies demonstrate the existence of a coupling between crystal field transitions and a transverse acoustic phonon mode.

  7. Ultrafast domain wall dynamics in magnetic nanotubes and nanowires

    Science.gov (United States)

    Hertel, R.

    2016-12-01

    The dynamic properties of magnetic domain walls in nanotubes and in cylindrical nanowires can be significantly different from the well known domain wall dynamics in thin films and in flat thin strips. The main differences are the occurrence of chiral symmetry breaking and, perhaps more importantly, the possibility to obtain magnetic domain walls that are stable against the usual Walker breakdown. This stability enables the magnetic field-driven propagation of the domain walls in nanotubes and nanocylinders at constant velocities which are significantly higher than the usual propagation speeds of the domain walls. Simulations predict that the ultrafast motion of magnetic domain walls at velocities in a range above 1000 m s-1 can lead to the spontaneous excitation of spin waves in a process that is the magnetic analog of the Cherenkov effect. In the case of solid cylindrical wires, the domain wall can contain a micromagnetic point singularity. We discuss the current knowledge on the ultrafast dynamics of such Bloch points, which remains still largely unexplored.

  8. Avoiding a Systematic Error in Assessing Fat Graft Survival in the Breast with Repeated Magnetic Resonance Imaging

    DEFF Research Database (Denmark)

    Glovinski, Peter Viktor; Herly, Mikkel; Müller, Felix C

    2016-01-01

    Several techniques for measuring breast volume (BV) are based on examining the breast on magnetic resonance imaging. However, when techniques designed to measure total BV are used to quantify BV changes, for example, after fat grafting, a systematic error is introduced because BV changes lead to ...... for assessing BV changes to determine fat graft retention and may be useful for evaluating and comparing available surgical techniques for breast augmentation and reconstruction using fat grafting.......Several techniques for measuring breast volume (BV) are based on examining the breast on magnetic resonance imaging. However, when techniques designed to measure total BV are used to quantify BV changes, for example, after fat grafting, a systematic error is introduced because BV changes lead...... to contour alterations of the breast. The volume of the altered breast includes not only the injected volume but also tissue previously surrounding the breast. Therefore, the quantitative difference in BV before and after augmentation will differ from the injected volume. Here, we present a new technique...

  9. Magnetic dynamics of fine particles studied by inelastic neutron scattering

    CERN Document Server

    Hansen, M F; Moerup, S; Lefmann, K; Clausen, K N; Lindgaard, P A

    2000-01-01

    We give an introduction to inelastic neutron scattering and the dynamic scattering function for magnetic nanoparticles. Differences between ferromagnetic and antiferromagnetic nanoparticles are discussed and we give a review of recent results on ferromagnetic Fe nanoparticles and canted antiferromagnetic alpha-Fe sub 2 O sub 3 nanoparticles.

  10. Magnetic string contribution to hadron dynamics in QCD

    NARCIS (Netherlands)

    Simonov, YA; Tjon, JA

    2000-01-01

    The dynamics of a light quark in the field of a static source (heavy-light meson) is studied using the nonlinear Dirac equation, derived recently. Special attention is paid to the contribution of the magnetic correlators and it is found that it yields a significant increase of string tension at inte

  11. Impact of Dynamic Magnetic fields on the CLIC Main Beam

    CERN Document Server

    Snuverink, J; Jach, C; Jeanneret, JB; Schulte, D; Stulle, F

    2010-01-01

    The Compact Linear Collider (CLIC) accelerator has strong precision requirements on the position of the beam. The beam position will be sensitive to external dynamic magnetic fields (stray fields) in the nanotesla regime. The impact of these fields on the CLIC main beam has been studied by performing simulations on the lattices and tolerances have been determined. Several mitigation techniques will be discussed.

  12. Magnetic string contribution to hadron dynamics in QCD /

    NARCIS (Netherlands)

    Simonov, Yu. A.; Tjon, J. A.

    2000-01-01

    Published in: Phys. Rev., D 62 (2000) 094511 citations recorded in [Science Citation Index] Abstract: Dynamics of a light quark in the field of static source (heavy-light meson) is studied using the nonlinear Dirac equation, derived recently. Special attention is paid to the contribution of magnetic

  13. Current-induced magnetization dynamics in disordered itinerant ferromagnets

    NARCIS (Netherlands)

    Tserkovnyak, Y.; Skadsem, H.J.; Brataas, A.; Bauer, G.E.W.

    2006-01-01

    Current-driven magnetization dynamics in ferromagnetic metals is studied in a self-consistent adiabatic local-density approximation in the presence of spin-conserving and spin-dephasing impurity scattering. Based on a quantum kinetic equation, we derive Gilbert damping and spin-transfer torques ente

  14. Spin currents and magnetization dynamics in multilayer systems

    NARCIS (Netherlands)

    van der Bijl, E.

    2014-01-01

    In this Thesis the interplay between spin currents and magnetization dynamics is investigated theoretically. With the help of a simple model the relevant physical phenomena are introduced. From this model it can be deduced that in systems with small spin-orbit coupling, current-induced torques on

  15. Vertically polarizing undulator with dynamic compensation of magnetic forces

    National Research Council Canada - National Science Library

    Strelnikov, N; Vasserman, I; Xu, J; Jensen, D; Schmidt, O; Trakhtenberg, E; Suthar, K; Moog, E. R; Pile, G; Gluskin, E

    2017-01-01

    As part of the R&D program of the LCLS-II project, a novel 3.4-meter-long undulator prototype with horizontal magnetic field and dynamic force compensation has recently been developed at the Advanced Photon Source (APS...

  16. Transtuzumab-conjugated liposome-coated fluorscent magnetic namoparticles to target breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Mi Jung; Lee, Hak Jong; Hwang, Sung Il; Yun, Bo La; Kim, Sun Mi [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Yoon, Young Il; Kwon, Yong Soo [Nanoimaging and Therapy Research Center, Institute of Nanoconvergence, Advanced Institutes of Convergence Technology, Seoul National University, Suwon (Korea, Republic of); Yoon, Tae Jong [NanoBio Materials Chemistry Lab., Dept. of Applied Bioscience, CHA University, Pocheon (Korea, Republic of)

    2014-08-15

    To synthesize mesoporous silica-core-shell magnetic nanoparticles (MNPs) encapsulated by liposomes (Lipo [MNPm-SiO{sub 2}]) in order to enhance their stability, allow them to be used in any buffer solution, and to produce trastuzumab-conjugated (Lipo[MNPm-SiO{sub 2}]-Her2Ab) nanoparticles to be utilized in vitro for the targeting of breast cancer. The physiochemical characteristics of Lipo[MNPm-SiO{sub 2}] were assessed in terms of size, morphological features, and in vitro safety. The multimodal imaging properties of the organic dye incorporated into Lipo[MNPm-SiO{sub 2}] were assessed with both in vitro fluorescence and MR imaging. The specific targeting ability of trastuzumab (Her2/neu antibody, Herceptin)-conjugated Lipo[MNPm-SiO{sub 2}] for Her2/neu-positive breast cancer cells was also evaluated with fluorescence and MR imaging. We obtained uniformly-sized and evenly distributed Lipo[MNPm-SiO{sub 2}] that demonstrated biological stability, while not disrupting cell viability. Her2/neu-positive breast cancer cell targeting by trastuzumab-conjugated Lipo[MNPm-SiO{sub 2}] was observed by in vitro fluorescence and MR imaging. Trastuzumab-conjugated Lipo[MNPm-SiO{sub 2}] is a potential treatment tool for targeted drug delivery in Her2/neu-positive breast cancer.

  17. Magnetic resonance imaging of radial sclerosing lesions (radial scars) of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Linda, Anna, E-mail: annalinda33@gmail.com [Institute of Diagnostic Radiology, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Udine (Italy); Zuiani, Chiara; Londero, Viviana [Institute of Diagnostic Radiology, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Udine (Italy); Cedolini, Carla [Department of Surgery, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Udine (Italy); Girometti, Rossano; Bazzocchi, Massimo [Institute of Diagnostic Radiology, Azienda Ospedaliero-Universitaria Santa Maria della Misericordia, Udine (Italy)

    2012-11-15

    Purpose: To identify magnetic resonance (MR) imaging (MRI) features of radial sclerosing lesions (RSLs) of the breast. Methods and materials: The radiologic and pathologic records for 4629 consecutive patients undergoing MR examinations of the breast were retrospectively reviewed. Patients who received a pathologic diagnosis of RSL without atypia or carcinoma at surgical excision were identified. The MR images were evaluated according to the BI-RADS-MRI lexicon by two experienced breast radiologists. The frequency of morphologic and kinetic patterns and of BI-RADS-MRI assessment categories was calculated. Results: Twenty-nine patients with 29 surgically excised RSL were identified. Nine (31%) RSL were MR-occult; the remaining 20 (69%) RSL presented as masses (10/20, 50%), architectural distortions (5/20, 25%), non-mass lesions (4/20, 20%), and focus (1/20, 5%). Kinetic analysis was performed in 18 RSL: enhancement features were benign in 9 (50%) cases, suspicious in 7 (39%) cases and indeterminate in 2 (11%) cases. Twelve (41%) MR examinations were assessed as suspicious (BI-RADS-MRI 4 and 5), and 17 (59%) as negative (BI-RADS-MRI 1) or benign (BI-RADS-MRI 2 and 3). Conclusion: RSLs are often visualized on MR imaging. Just as in mammography and sonography, RSL can have variable morphologic and kinetic features, and not infrequently they can mimic invasive carcinoma of the breast.

  18. Dynamically important magnetic fields near accreting supermassive black holes.

    Science.gov (United States)

    Zamaninasab, M; Clausen-Brown, E; Savolainen, T; Tchekhovskoy, A

    2014-06-05

    Accreting supermassive black holes at the centres of active galaxies often produce 'jets'--collimated bipolar outflows of relativistic particles. Magnetic fields probably play a critical role in jet formation and in accretion disk physics. A dynamically important magnetic field was recently found near the Galactic Centre black hole. If this is common and if the field continues to near the black hole event horizon, disk structures will be affected, invalidating assumptions made in standard models. Here we report that jet magnetic field and accretion disk luminosity are tightly correlated over seven orders of magnitude for a sample of 76 radio-loud active galaxies. We conclude that the jet-launching regions of these radio-loud galaxies are threaded by dynamically important fields, which will affect the disk properties. These fields obstruct gas infall, compress the accretion disk vertically, slow down the disk rotation by carrying away its angular momentum in an outflow and determine the directionality of jets.

  19. Spin motive force driven by skyrmion dynamics in magnetic nanodisks

    Science.gov (United States)

    Shimada, Yuhki; Ohe, Jun-ichiro

    2015-05-01

    The spin motive force driven by the dynamics of the skyrmion structure formed in a nanomagnetic disk is numerically investigated. Due to the existence of the magnetic structure along the disk edge, the collective mode of the magnetization is modified from that of the bulk skyrmion lattice obtained by using the periodic boundary condition. For a single-skyrmion disk, the dynamics of the skyrmion core and the edge magnetization induce the spin motive force, and a measurable AC voltage is obtained by two probes on the disk. For a multi-skyrmions disk, the phase-locked collective mode of skyrmions is found in the lowest resonant frequency where the amplitude of the AC voltage is enhanced by the cascade effect of the spin motive force. We also investigate the effect of the Rashba spin-orbit coupling on the spin motive force.

  20. Dynamics of a self-gravitating magnetized neutron source

    CERN Document Server

    Paret, D Manreza

    2008-01-01

    The dynamics of a self-gravitating neutron gas in presence of a magnetic field is being studied taking the equation of state of a magnetized neutron gas obtained in a previous study [1]. We work in a Bianchi I spacetime characterized by a Kasner metric, this metric allow us to take into account the anisotropy that introduces the magnetic field. The set of Einstein-Maxwell field equations for this gas becomes a dynamical system in a 4-dimensional phase space. We get numerical solutions of the system. In particular there is a unique point like solution for different initial conditions. Physically this singular solution may be associated with the collapse of a local volume of neutron material within a neutron star.

  1. 3.0 Tesla vs 1.5 Tesla breast magnetic resonance imaging in newly diagnosed breast cancer patients

    Science.gov (United States)

    Butler, Reni S; Chen, Christine; Vashi, Reena; Hooley, Regina J; Philpotts, Liane E

    2013-01-01

    AIM: To compare 3.0 Tesla (T) vs 1.5T magnetic resonance (MR) imaging systems in newly diagnosed breast cancer patients. METHODS: Upon Institutional Review Board approval, a Health Insurance Portability and Accountability Act-compliant retrospective review of 147 consecutive 3.0T MR examinations and 98 consecutive 1.5T MR examinations in patients with newly diagnosed breast cancer between 7/2009 and 5/2010 was performed. Eleven patients who underwent neoadjuvant chemotherapy in the 3.0T group were excluded. Mammographically occult suspicious lesions (BIRADS Code 4 and 5) additional to the index cancer in the ipsilateral and contralateral breast were identified. Lesion characteristics and pathologic diagnoses were recorded, and results achieved with both systems compared. Statistical significance was analyzed using Fisher’s exact test. RESULTS: In the 3.0T group, 206 suspicious lesions were identified in 55% (75/136) of patients and 96% (198/206) of these lesions were biopsied. In the 1.5T group, 98 suspicious lesions were identified in 53% (52/98) of patients and 90% (88/98) of these lesions were biopsied. Biopsy results yielded additional malignancies in 24% of patients in the 3.0T group vs 14% of patients in the 1.5T group (33/136 vs 14/98, P = 0.07). Average size and histology of the additional cancers was comparable. Of patients who had a suspicious MR imaging study, additional cancers were found in 44% of patients in the 3.0T group vs 27% in the 1.5T group (33/75 vs 14/52, P = 0.06), yielding a higher positive predictive value (PPV) for biopsies performed with the 3.0T system. CONCLUSION: 3.0T MR imaging detected more additional malignancies in patients with newly diagnosed breast cancer and yielded a higher PPV for biopsies performed with the 3.0T system. PMID:24003354

  2. The evolving role of the dynamic thermal analysis in the early detection of breast cancer

    Science.gov (United States)

    Salhab, M; Al Sarakbi, W; Mokbel, K

    2005-01-01

    It is now recognised that the breast exhibits a circadian rhythm which reflects its physiology. There is increasing evidence that rhythms associated with malignant cells proliferation are largely non-circadian and that a circadian to ultradian shift may be a general correlation to neoplasia. Cancer development appears to generate its own thermal signatures and the complexity of these signatures may be a reflection of its degree of development. The limitations of mammography as a screening modality especially in young women with dense breasts necessitated the development of novel and more effective screening strategies with a high sensitivity and specificity. Dynamic thermal analysis of the breast is a safe, non invasive approach that seems to be sensitive for the early detection of breast cancer. This article focuses on dynamic thermal analysis as an evolving method in breast cancer detection in pre-menopausal women with dense breast tissue. Prospective multi-centre trials are required to validate this promising modality in screening. The issue of false positives require further investigation using molecular genetic markers of malignancy and novel techniques such as mammary ductoscopy. PMID:15819982

  3. Plasma-induced magnetic responses during nonlinear dynamics of magnetic islands due to resonant magnetic perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Seiya, E-mail: n-seiya@kobe-kosen.ac.jp [Kobe City College of Technology, Kobe, Hyogo 651-2194 (Japan)

    2014-12-15

    Resonant magnetic perturbations (RMPs) produce magnetic islands in toroidal plasmas. Self-healing (annihilation) of RMP-induced magnetic islands has been observed in helical systems, where a possible mechanism of the self-healing is shielding of RMP penetration by plasma flows, which is well known in tokamaks. Thus, fundamental physics of RMP shielding is commonly investigated in both tokamaks and helical systems. In order to check this mechanism, detailed informations of magnetic island phases are necessary. In experiments, measurement of radial magnetic responses is relatively easy. In this study, based on a theoretical model of rotating magnetic islands, behavior of radial magnetic fields during the self-healing is investigated. It is confirmed that flips of radial magnetic fields are typically observed during the self-healing. Such behavior of radial magnetic responses is also observed in LHD experiments.

  4. Wavelet-based multifractal analysis of dynamic infrared thermograms to assist in early breast cancer diagnosis

    Directory of Open Access Journals (Sweden)

    Evgeniya eGerasimova

    2014-05-01

    Full Text Available Breast cancer is the most common type of cancer among women and despite recent advances in the medical field, there are still some inherent limitations in the currently used screening techniques. The radiological interpretation of screening X-ray mammograms often leads to over-diagnosis and, as a consequence, to unnecessary traumatic and painful biopsies. Here we propose a computer-aided multifractal analysis of dynamic infrared (IR imaging as an efficient method for identifying women with risk of breast cancer. Using a wavelet-based multi-scale method to analyze the temporal fluctuations of breast skin temperature collected from a panel of patients with diagnosed breast cancer and some female volunteers with healthy breasts, we show that the multifractal complexity of temperature fluctuations observed in healthy breasts is lost in mammary glands with malignant tumor. Besides potential clinical impact, these results open new perspectives in the investigation of physiological changes that may precede anatomical alterations in breast cancer development.

  5. Fractional dynamics of charged particles in magnetic fields

    Science.gov (United States)

    Coronel-Escamilla, A.; Gómez-Aguilar, J. F.; Alvarado-Méndez, E.; Guerrero-Ramírez, G. V.; Escobar-Jiménez, R. F.

    2016-02-01

    In many physical applications the electrons play a relevant role. For example, when a beam of electrons accelerated to relativistic velocities is used as an active medium to generate Free Electron Lasers (FEL), the electrons are bound to atoms, but move freely in a magnetic field. The relaxation time, longitudinal effects and transverse variations of the optical field are parameters that play an important role in the efficiency of this laser. The electron dynamics in a magnetic field is a means of radiation source for coupling to the electric field. The transverse motion of the electrons leads to either gain or loss energy from or to the field, depending on the position of the particle regarding the phase of the external radiation field. Due to the importance to know with great certainty the displacement of charged particles in a magnetic field, in this work we study the fractional dynamics of charged particles in magnetic fields. Newton’s second law is considered and the order of the fractional differential equation is (0;1]. Based on the Grünwald-Letnikov (GL) definition, the discretization of fractional differential equations is reported to get numerical simulations. Comparison between the numerical solutions obtained on Euler’s numerical method for the classical case and the GL definition in the fractional approach proves the good performance of the numerical scheme applied. Three application examples are shown: constant magnetic field, ramp magnetic field and harmonic magnetic field. In the first example the results obtained show bistability. Dissipative effects are observed in the system and the standard dynamic is recovered when the order of the fractional derivative is 1.

  6. The large-scale dynamics of magnetic helicity

    CERN Document Server

    Linkmann, Moritz

    2016-01-01

    In this Letter we investigate the dynamics of magnetic helicity in magnetohydrodynamic (MHD) turbulent flows focusing at scales larger than the forcing scale. Our results show a non-local inverse cascade of magnetic helicity, which occurs directly from the forcing scale into the largest scales of the magnetic fields. We also observe that no magnetic helicity and no energy is transferred to an intermediate range of scales sufficiently smaller than the container size and larger than the forcing scale. Thus, the statistical properties of this range of scales, which increases with scale separation, is shown to be described to a large extent by the zero-flux solutions of the absolute statistical equilibrium theory exhibited by the truncated ideal MHD equations.

  7. Dynamical structure of magnetized dissipative accretion flow around black holes

    CERN Document Server

    Sarkar, Biplob

    2016-01-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accret...

  8. Dynamics of Chromospheric Upflows and Underlying Magnetic Fields

    CERN Document Server

    Yurchyshyn, Vasyl; Goode, Phil

    2013-01-01

    We used \\ha-0.1 nm and magnetic field (at 1.56$\\mu$) data obtained with the New Solar Telescope to study the origin of the disk counterparts to type II spicules, so-called rapid blueshifted excursions (RBEs). The high time cadence of our chromospheric (10 s) and magnetic field (45 s) data allowed us to generate x-t plots using slits parallel to the spines of the RBEs. These plots, along with potential field extrapolation, led us to suggest that the occurrence of RBEs is generally correlated with the appearance of new, mixed or unipolar fields in close proximity to network fields. RBEs show a tendency to occur at the interface between large-scale fields and small-scale dynamic magnetic loops and thus are likely to be associated with existence of a magnetic canopy. Detection of kinked and/or inverse "Y" shaped RBEs further confirm this conclusion.

  9. Photospheric and Subphotospheric Dynamics of Emerging Magnetic Flux

    Science.gov (United States)

    Kosovichev, A. G.

    2009-04-01

    Magnetic fields emerging from the Sun’s interior carry information about physical processes of magnetic field generation and transport in the convection zone. Soon after appearance on the solar surface the magnetic flux gets concentrated in sunspot regions and causes numerous active phenomena on the Sun. This paper discusses some properties of the emerging magnetic flux observed on the solar surface and in the interior. A statistical analysis of variations of the tilt angle of bipolar magnetic regions during the emergence shows that the systematic tilt with respect to the equator (the Joy’s law) is most likely established below the surface. However, no evidence of the dependence of the tilt angle on the amount of emerging magnetic flux, predicted by the rising magnetic flux rope theories, is found. Analysis of surface plasma flows in a large emerging active region reveals strong localized upflows and downflows at the initial phase of emergence but finds no evidence for large-scale flows indicating future appearance a large-scale magnetic structure. Local helioseismology provides important tools for mapping perturbations of the wave speed and mass flows below the surface. Initial results from SOHO/MDI and GONG reveal strong diverging flows during the flux emergence, and also localized converging flows around stable sunspots. The wave speed images obtained during the process of formation of a large active region, NOAA 10488, indicate that the magnetic flux gets concentrated in strong field structures just below the surface. Further studies of magnetic flux emergence require systematic helioseismic observations from the ground and space, and realistic MHD simulations of the subsurface dynamics.

  10. Taub-NUT Dynamics with a Magnetic Field

    CERN Document Server

    Jante, Rogelio

    2015-01-01

    We study classical and quantum dynamics on the Euclidean Taub-NUT geometry coupled to an abelian gauge field with self-dual curvature and show that, even though Taub-NUT has neither bounded orbits nor quantum bound states, the magnetic binding via the gauge field produces both. The conserved Runge-Lenz vector of Taub-NUT dynamics survives, in a modified form, in the gauged model and allows for an essentially algebraic computation of classical trajectories and energies of quantum bound states. We also compute scattering cross sections and find a surprising electric-magnetic duality. Finally, we exhibit the dynamical symmetry behind the conserved Runge-Lenz and angular momentum vectors in terms of a twistorial formulation of phase space.

  11. Taub-NUT dynamics with a magnetic field

    Science.gov (United States)

    Jante, Rogelio; Schroers, Bernd J.

    2016-06-01

    We study classical and quantum dynamics on the Euclidean Taub-NUT geometry coupled to an abelian gauge field with self-dual curvature and show that, even though Taub-NUT has neither bounded orbits nor quantum bound states, the magnetic binding via the gauge field produces both. The conserved Runge-Lenz vector of Taub-NUT dynamics survives, in a modified form, in the gauged model and allows for an essentially algebraic computation of classical trajectories and energies of quantum bound states. We also compute scattering cross sections and find a surprising electric-magnetic duality. Finally, we exhibit the dynamical symmetry behind the conserved Runge-Lenz and angular momentum vectors in terms of a twistorial formulation of phase space.

  12. Ab initio theory for ultrafast magnetization dynamics with a dynamic band structure

    Science.gov (United States)

    Mueller, B. Y.; Haag, M.; Fähnle, M.

    2016-09-01

    Laser-induced modifications of magnetic materials on very small spatial dimensions and ultrashort timescales are a promising field for novel storage and spintronic devices. Therefore, the contribution of electron-electron spin-flip scattering to the ultrafast demagnetization of ferromagnets after an ultrashort laser excitation is investigated. In this work, the dynamical change of the band structure resulting from the change of the magnetization in time is taken into account on an ab initio level. We find a large influence of the dynamical band structure on the magnetization dynamics and we illustrate the thermalization and relaxation process after laser irradiation. Treating the dynamical band structure yields a demagnetization comparable to the experimental one.

  13. Ultrafast Magnetism Dynamics Measure Using Tabletop Ultrafast EUV Sources

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Thomas J. [NIST; Murnane, Margaret [University of Colorado

    2013-08-21

    In our work to date, we made two significant advances. First we demonstrated element-selective demagnetization dynamics for the first time, with a record time resolution for x-ray probing of 55 fs. Second, in new work, we were able to probe the timescale of the exchange interaction in magnetic materials, also for the first time. Our measurements were made using the transverse magneto-optic Kerr effect (T-MOKE) geometry, since the reflectivity of a magnetic material changes with the direction of the magnetization vector of a surface. In our experiment, we periodically reversed the magnetization direction of a grating structure made of Permalloy (Ni80Fe20) using an external magnetic field. To achieve maximum contrast, we used HHG light spanning the M-shell (3p) absorption edges of Fe and Ni. Our characterization of the static magnetization of a Permalloy sample shows high magnetic asymmetry at photon energies just above and below the absorption edges at 55 eV and 65 eV, respectively. This result is in excellent agreement with measurements done on the same using a synchrotron source.

  14. Background Parenchymal Enhancement on Preoperative Magnetic Resonance Imaging: Association With Recurrence-Free Survival in Breast Cancer Patients Treated With Neoadjuvant Chemotherapy.

    Science.gov (United States)

    Choi, Ji Soo; Ko, Eun Sook; Ko, Eun Young; Han, Boo-Kyung; Nam, Seok Jin

    2016-03-01

    To retrospectively investigate whether background parenchymal enhancement (BPE) of the contralateral breast on preoperative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is associated with therapeutic outcomes following neoadjuvant chemotherapy (NAC) in unilateral invasive breast cancer. The institutional review board approved this study, and informed consent was waived. Between 2009 and 2011, 93 women with unilateral invasive breast cancer (43 premenopausal women who performed pre-NAC MRI between days 7 and 20 of the menstrual cycle and 50 postmenopausal women) underwent NAC with pre- and post-NAC DCE-MRI before surgery. MRI features (BPE [minimal, mild, moderate, marked] of the contralateral breast, lesion size and number, lesion kinetics, and changes in lesion size) and clinicopathologic features were analyzed. Patients were grouped according to BPE category (high [moderate or marked] or low [minimal or mild]). Cox regression modeling was used to determine associations between MRI features and recurrence-free survival (RFS) after controlling for clinicopathologic variables. The mean follow-up period was 48.2 months. Twenty-three recurrences occurred (2 ipsilateral breasts, 6 regional, and 15 distant). On multivariate analysis, high BPE on pre-NAC MRI (hazard ratio [HR] = 3.851, P = 0.006) and triple-negative cancer (HR = 3.192, P = 0.002) were independent factors associated with worse RFS. A greater reduction of lesion size on post-NAC MRI (HR = 0.984, P = 0.021) was associated with better RFS. High BPE on pre-NAC MRI is significantly associated with worse RFS in an NAC setting. This study suggests that BPE on pre-NAC DCE-MRI may have potential as a predictor of long-term outcomes in breast cancer patients who undergo NAC.

  15. Dynamic material strength measurement utilizing magnetically applied pressure-shear

    Directory of Open Access Journals (Sweden)

    Alexander C.S.

    2012-08-01

    Full Text Available Magnetically applied pressure-shear (MAPS is a recently developed technique used to measure dynamic material strength developed at Sandia National Laboratories utilizing magneto-hydrodynamic (MHD drive pulsed power systems. MHD drive platforms generate high pressures by passing a large current through a pair of parallel plate conductors which, in essence, form a single turn magnet coil. Lorentz forces resulting from the interaction of the self-generated magnetic field and the drive current repel the plates and result in a high pressure ramp wave propagating in the conductors. This is the principle by which the Sandia Z Machine operates for dynamic material testing. MAPS relies on the addition of a second, external magnetic field applied orthogonally to both the drive current and the self-generated magnetic field. The interaction of the drive current and this external field results in a shear wave being induced directly in the conductors. Thus both longitudinal and shear stresses are generated. These stresses are coupled to a sample material of interest where shear strength is probed by determining the maximum transmissible shear stress in the state defined by the longitudinal compression. Both longitudinal and transverse velocities are measured via a specialized velocity interferometer system for any reflector (VISAR. Pressure and shear strength of the sample are calculated directly from the VISAR data. Results of tests on several materials at modest pressures (∼10GPa will be presented and discussed.

  16. Observations of Magnetic Reconnection and Plasma Dynamics in Mercury's Magnetosphere

    Science.gov (United States)

    DiBraccio, Gina A.

    Mercury's magnetosphere is formed as a result of the supersonic solar wind interacting with the planet's intrinsic magnetic field. The combination of the weak planetary dipole moment and intense solar wind forcing of the inner heliosphere creates a unique space environment, which can teach us about planetary magnetospheres. In this work, we analyze the first in situ orbital observations at Mercury, provided by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Magnetic reconnection and the transport of plasma and magnetic flux are investigated using MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer measurements. Here, we report our results on the effect of magnetic reconnection and plasma dynamics on Mercury's space environment: (1) Mercury's magnetosphere is driven by frequent, intense magnetic reconnection observed in the form of magnetic field components normal to the magnetopause, BN, and as helical bundles of flux, called magnetic flux ropes, in the cross-tail current sheet. The high reconnection rates are determined to be a direct consequence of the low plasma beta, the ratio of plasma to magnetic pressure, in the inner heliosphere. (2) As upstream solar wind conditions vary, we find that reconnection occurs at Mercury's magnetopause for all orientations of the interplanetary magnetic field, independent of shear angle. During the most extreme solar wind forcing events, the influence of induction fields generated within Mercury's highly conducting core are negated by erosion due to persistent magnetopause reconnection. (3) We present the first observations of Mercury's plasma mantle, which forms as a result of magnetopause reconnection and allows solar wind plasma to enter into the high-latitude magnetotail through the dayside cusps. The energy dispersion observed in the plasma mantle protons is used to infer the cross-magnetosphere electric field, providing a direct measurement of solar wind momentum

  17. A review of dynamic characteristics of magnetically levitated vehicle systems

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Y.; Chen, S.S.

    1995-11-01

    The dynamic response of magnetically levitated (maglev) ground transportation systems has important consequences for safety and ride quality, guideway design, and system costs. Ride quality is determined by vehicle response and by environmental factors such as humidity and noise. The dynamic response of the vehicles is the key element in determining ride quality, while vehicle stability is an important safety-related element. To design a guideway that provides acceptable ride quality in the stable region, vehicle dynamics must be understood. Furthermore, the trade-off between guideway smoothness and levitation and control systems must be considered if maglev systems are to be economically feasible. The link between the guideway and the other maglev components is vehicle dynamics. For a commercial maglev system, vehicle dynamics must be analyzed and tested in detail. This report, which reviews various aspects of the dynamic characteristics, experiments and analysis, and design guidelines for maglev systems, discusses vehicle stability, motion dependent magnetic force components, guideway characteristics, vehicle/ guideway interaction, ride quality, suspension control laws, aerodynamic loads and other excitations, and research needs.

  18. Dynamics of genomic clones in breast cancer patient xenografts at single cell resolution

    Science.gov (United States)

    Eirew, Peter; Steif, Adi; Khattra, Jaswinder; Ha, Gavin; Yap, Damian; Farahani, Hossein; Gelmon, Karen; Chia, Stephen; Mar, Colin; Wan, Adrian; Laks, Emma; Biele, Justina; Shumansky, Karey; Rosner, Jamie; McPherson, Andrew; Nielsen, Cydney; Roth, Andrew J. L.; Lefebvre, Calvin; Bashashati, Ali; de Souza, Camila; Siu, Celia; Aniba, Radhouane; Brimhall, Jazmine; Oloumi, Arusha; Osako, Tomo; Bruna, Alejandra; Sandoval, Jose; Algara, Teresa; Greenwood, Wendy; Leung, Kaston; Cheng, Hongwei; Xue, Hui; Wang, Yuzhuo; Lin, Dong; Mungall, Andrew J.; Moore, Richard; Zhao, Yongjun; Lorette, Julie; Nguyen, Long; Huntsman, David; Eaves, Connie J.; Hansen, Carl; Marra, Marco A.; Caldas, Carlos; Shah, Sohrab P.; Aparicio, Samuel

    2016-01-01

    Human cancers, including breast cancers, are comprised of clones differing in mutation content. Clones evolve dynamically in space and time following principles of Darwinian evolution1,2, underpinning important emergent features such as drug resistance and metastasis3–7. Human breast cancer xenoengraftment is used as a means of capturing and studying tumour biology, and breast tumour xenografts are generally assumed to be reasonable models of the originating tumours8–10. However the consequences and reproducibility of engraftment and propagation on the genomic clonal architecture of tumours has not been systematically examined at single cell resolution. Here we show by both deep genome and single cell sequencing methods, the clonal dynamics of initial engraftment and subsequent serial propagation of primary and metastatic human breast cancers in immunodeficient mice. In all 15 cases examined, clonal selection on engraftment was observed in both primary and metastatic breast tumours, varying in degree from extreme selective engraftment of minor (<5% of starting population) clones to moderate, polyclonal engraftment. Furthermore, ongoing clonal dynamics during serial passaging is a feature of tumours experiencing modest initial selection. Through single cell sequencing, we show that major mutation clusters estimated from tumour population sequencing relate predictably to the most abundant clonal genotypes, even in clonally complex and rapidly evolving cases. Finally, we show that similar clonal expansion patterns can emerge in independent grafts of the same starting tumour population, indicating that genomic aberrations can be reproducible determinants of evolutionary trajectories. Our results show that measurement of genomically defined clonal population dynamics will be highly informative for functional studies utilizing patient-derived breast cancer xenoengraftment. PMID:25470049

  19. Characterization of the enhancing lesions on dynamic contrast enhanced magnetic resonance imaging in patients with interstitial mammoplasty

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Yun [Department of Radiology, Seoul St. Mary' s Hospital, The Catholic University of Korea (Korea, Republic of); Kim, Sung Hun, E-mail: rad-ksh@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, The Catholic University of Korea (Korea, Republic of); Kang, Bong Joo [Department of Radiology, Seoul St. Mary' s Hospital, The Catholic University of Korea (Korea, Republic of); Kim, Hyeon Sook [Department of Radiology, St. Paul Hospital, The Catholic University of Korea (Korea, Republic of); Cha, Eun Suk [Department of Radiology, Ewha Womans University, School of Medicine, Mokdong Hospital (Korea, Republic of); Kim, Ji Youn [Department of Radiology, Yeouido St. Mary' s Hospital, The Catholic University of Korea (Korea, Republic of); Song, Byung Joo [Department of Surgery, Seoul St. Mary' s Hospital, The Catholic University of Korea, Seoul (Korea, Republic of)

    2013-12-01

    Purpose: The purpose of this study was to categorize the morphologic and kinetic features of enhancing lesions in breasts with interstitial mammoplasty using dynamic contrast-enhanced magnetic resonance imaging and to assess factors predictive of breast cancer. Materials and methods: We retrospectively reviewed the clinical and radiological data of 21 enhancing lesions in 19 patients with interstitial mammoplasty, who underwent breast magnetic resonance imaging and biopsy or an operation in our hospital from September 2008 to July 2012. These lesions were sorted by morphological and kinetic features and final assessment category according to the BI-RADS lexicon. Results: Nine cases were confirmed to be ductal carcinoma in situ (n = 2) and invasive ductal carcinoma (n = 7), and the remaining 12 cases were fibrocystic disease (n = 2), fibroadenoma (n = 2), fat necrosis (n = 1), foreign body granuloma (n = 3) and silicone mastitis (n = 1). Common features of malignancy included irregular shape (50.0%), spiculated margins (75.0%), heterogeneous enhancement (50.0%) and type III kinetic pattern (87.5%). The correlations of margins and kinetic curve pattern with benignity and malignancy approached statistical significance (p = 0.02, respectively). We found no correlation for shape (p = 0.33) or internal enhancement (p = 0.42) between lesion types. The malignancy rate of enhancing lesions was 42.8% (9/21). The sensitivity and specificity of dynamic contrast-enhanced magnetic resonance imaging were 100% and 16.67%, respectively. The positive predictive value, negative predictive value and accuracy of magnetic resonance imaging were 47.38%, 100% and 52.38%. Overall inter-observer agreement for the kinetic curve pattern was good (κ = 0.67). Moderate agreement was seen in describing the shape, margin, enhancement and assessing the final category (κ = 0.59, 0.46, 0.58 and 0.49, respectively). Conclusion: Dynamic contrast-enhanced magnetic resonance imaging had a high

  20. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... a set of static magnetic filed analysis is carried out and then the electric circuit and mechanical motion equations are solved employing bi-cubic spline approximations of the field analysis results. The results show that the proposed decoupled model is of satisfactory accuracy and gives more...

  1. Functional Magnetic Resonance Imaging in Assessing Affect Reactivity and Regulation in Patients With Stage 0-III Breast Cancer

    Science.gov (United States)

    2017-02-27

    Healthy Subject; Stage 0 Breast Cancer; Stage IA Breast Cancer; Stage IB Breast Cancer; Stage IIA Breast Cancer; Stage IIB Breast Cancer; Stage IIIA Breast Cancer; Stage IIIB Breast Cancer; Stage IIIC Breast Cancer

  2. A Compressive Sensing Approach for 3D Breast Cancer Microwave Imaging With Magnetic Nanoparticles as Contrast Agent.

    Science.gov (United States)

    Bevacqua, Martina T; Scapaticci, Rosa

    2016-02-01

    In microwave breast cancer imaging magnetic nanoparticles have been recently proposed as contrast agent. Due to the non-magnetic nature of human tissues, magnetic nanoparticles make possible the overcoming of some limitations of conventional microwave imaging techniques, thus providing reliable and specific diagnosis of breast cancer. In this paper, a Compressive Sensing inspired inversion technique is introduced for the reconstruction of the magnetic contrast induced within the tumor. The applicability of Compressive Sensing theory is guaranteed by the fact that the underlying inverse scattering problem is linear and the searched magnetic perturbation is sparse. From the numerical analysis, performed in realistic conditions in 3D geometry, it has been pointed out that the adoption of this new tool allows improving resolution and accuracy of the reconstructions, as well as reducing the number of required measurements.

  3. The Magnetic Nanoparticle Movement in Magnetic Fluid Characterized by the Laser Dynamic Speckle Interferometry

    Directory of Open Access Journals (Sweden)

    Xijun Wang

    2014-01-01

    Full Text Available A dual scanning laser speckle interferometry experiment was designed to observe the dynamic behavior of the magnetic fluid actuated by a magnetic field. In order to improve the spatial resolution of the dynamic speckle measurement, the phase delay scanning was used to compensate the additional phase variation which was caused by the transverse scanning. The correlation coefficients corresponding to the temporal dynamic speckle patterns within the same time interval scattering from the nanoparticles were calculated in the experiment on nanoscale magnetic clusters. In the experiment, the speckle of the magnetic nanoparticle fluid movement has been recorded by the lens unmounted CCD within the interferometry strips, although the speckle led to the distinguished annihilation of the light coherence. The results have showed that the nanoparticle fluid dynamic properties appeared synergistically in the fringe speckles. The analyses of the nanoparticle's relative speed and the speckle pattern moving amount in the fringes have proved the nanoparticle’s movement in a laminar flow in the experiment.

  4. Effect of alignment of easy axes on dynamic magnetization of immobilized magnetic nanoparticles

    Science.gov (United States)

    Yoshida, Takashi; Matsugi, Yuki; Tsujimura, Naotaka; Sasayama, Teruyoshi; Enpuku, Keiji; Viereck, Thilo; Schilling, Meinhard; Ludwig, Frank

    2017-04-01

    In some biomedical applications of magnetic nanoparticles (MNPs), the particles are physically immobilized. In this study, we explore the effect of the alignment of the magnetic easy axes on the dynamic magnetization of immobilized MNPs under an AC excitation field. We prepared three immobilized MNP samples: (1) a sample in which easy axes are randomly oriented, (2) a parallel-aligned sample in which easy axes are parallel to the AC field, and (3) an orthogonally aligned sample in which easy axes are perpendicular to the AC field. First, we show that the parallel-aligned sample has the largest hysteresis in the magnetization curve and the largest harmonic magnetization spectra, followed by the randomly oriented and orthogonally aligned samples. For example, 1.6-fold increase was observed in the area of the hysteresis loop of the parallel-aligned sample compared to that of the randomly oriented sample. To quantitatively discuss the experimental results, we perform a numerical simulation based on a Fokker-Planck equation, in which probability distributions for the directions of the easy axes are taken into account in simulating the prepared MNP samples. We obtained quantitative agreement between experiment and simulation. These results indicate that the dynamic magnetization of immobilized MNPs is significantly affected by the alignment of the easy axes.

  5. Cluster analysis of signal-intensity time course in dynamic breast MRI: does unsupervised vector quantization help to evaluate small mammographic lesions?

    Energy Technology Data Exchange (ETDEWEB)

    Leinsinger, Gerda; Schlossbauer, Thomas; Scherr, Michael; Lange, Oliver; Reiser, Maximilian; Wismueller, Axel [Institute for Clinical Radiology University of Munich, Munich (Germany)

    2006-05-15

    We examined whether neural network clustering could support the characterization of diagnostically challenging breast lesions in dynamic magnetic resonance imaging (MRI). We examined 88 patients with 92 breast lesions (51 malignant, 41 benign). Lesions were detected by mammography and classified Breast Imaging and Reporting Data System (BIRADS) III (median diameter 14 mm). MRI was performed with a dynamic T1-weighted gradient echo sequence (one precontrast and five postcontrast series). Lesions with an initial contrast enhancement {>=}50% were selected with semiautomatic segmentation. For conventional analysis, we calculated the mean initial signal increase and postinitial course of all voxels included in a lesion. Secondly, all voxels within the lesions were divided into four clusters using minimal-free-energy vector quantization (VQ). With conventional analysis, maximum accuracy in detecting breast cancer was 71%. With VQ, a maximum accuracy of 75% was observed. The slight improvement using VQ was mainly achieved by an increase of sensitivity, especially in invasive lobular carcinoma and ductal carcinoma in situ (DCIS). For lesion size, a high correlation between different observers was found (R{sup 2} = 0.98). VQ slightly improved the discrimination between malignant and benign indeterminate lesions (BIRADS III) in comparison with a standard evaluation method. (orig.)

  6. Improvement in dynamic magnetic resonance imaging thermometry

    Science.gov (United States)

    Guo, Jun-Yu

    This dissertation is focused on improving MRI Thermometry (MRIT) techniques. The application of the spin-lattice relaxation constant is investigated in which T1 is used as indicator to measure the temperature of flowing fluid such as blood. Problems associated with this technique are evaluated, and a new method to improve the consistency and repeatability of T1 measurements is presented. The new method combines curve fitting with a measure of the curve null point to acquire more accurate and consistent T1 values. A novel method called K-space Inherited Parallel Acquisition (KIPA) is developed to achieve faster dynamic temperature measurements. Localized reconstruction coefficients are used to achieve higher reduction factors, and lower noise and artifact levels compared to that of GeneRalized Autocalibrating Partially Parallel Acquisition (GRAPPA) reconstruction. Artifacts in KIPA images are significantly reduced, and SNR is largely improved in comparison with that in GRAPPA images. The Root-Mean-Square (RMS) error of temperature for GRAPPA is 2 to 5 times larger than that for KIPA. Finally, the accuracy and comparison of the effects of motion on three parallel imaging methods: SENSE (SENSitivity Encoding), VSENSE (Variable-density SENSE) and KIPA are estimated. According to the investigation, KIPA is the most accurate and robust method among all three methods for studies with or without motion. The ratio of the normalized RMS (NRMS) error for SENSE to that for KIPA is within the range from 1 to 3.7. The ratio of the NRMS error for VSENSE to that for KIPA is about 1 to 2. These factors change with the reduction factor, motion and subject. In summary, the new strategy and method for the fast noninvasive measurement of T1 of flowing blood are proposed to improve stability and precision. The novel parallel reconstruction algorithm, KIPA, is developed to improve the temporal and spatial resolution for the PRF method. The motion effects on the KIPA method are also

  7. Nonlinear dynamic susceptibilities of interacting and noninteracting magnetic nanoparticles

    CERN Document Server

    Joensson, P; García-Palacios, J L; Svedlindh, P

    2000-01-01

    The linear and cubic dynamic susceptibilities of solid dispersions of nanosized maghemite gamma-Fe sub 2 O sub 3 particles have been measured for three samples with a volume concentration of magnetic particles ranging from 0.3% to 17%, in order to study the effect of dipole-dipole interactions. Significant differences between the dynamic response of the samples are observed. While the linear and cubic dynamic susceptibilities of the most dilute sample compare reasonably well with the corresponding expressions proposed by Raikher and Stepanov for noninteracting particles, the nonlinear dynamic response of the most concentrated sample exhibits at low temperatures similar features as observed in a Ag(11 at% Mn) spin glass.

  8. Computational Analysis of Static and Dynamic Behaviour of Magnetic Suspensions and Magnetic Bearings

    Science.gov (United States)

    Britcher, Colin P. (Editor); Groom, Nelson J.

    1996-01-01

    Static modelling of magnetic bearings is often carried out using magnetic circuit theory. This theory cannot easily include nonlinear effects such as magnetic saturation or the fringing of flux in air-gaps. Modern computational tools are able to accurately model complex magnetic bearing geometries, provided some care is exercised. In magnetic suspension applications, the magnetic fields are highly three-dimensional and require computational tools for the solution of most problems of interest. The dynamics of a magnetic bearing or magnetic suspension system can be strongly affected by eddy currents. Eddy currents are present whenever a time-varying magnetic flux penetrates a conducting medium. The direction of flow of the eddy current is such as to reduce the rate-of-change of flux. Analytic solutions for eddy currents are available for some simplified geometries, but complex geometries must be solved by computation. It is only in recent years that such computations have been considered truly practical. At NASA Langley Research Center, state-of-the-art finite-element computer codes, 'OPERA', 'TOSCA' and 'ELEKTRA' have recently been installed and applied to the magnetostatic and eddy current problems. This paper reviews results of theoretical analyses which suggest general forms of mathematical models for eddy currents, together with computational results. A simplified circuit-based eddy current model proposed appears to predict the observed trends in the case of large eddy current circuits in conducting non-magnetic material. A much more difficult case is seen to be that of eddy currents in magnetic material, or in non-magnetic material at higher frequencies, due to the lower skin depths. Even here, the dissipative behavior has been shown to yield at least somewhat to linear modelling. Magnetostatic and eddy current computations have been carried out relating to the Annular Suspension and Pointing System, a prototype for a space payload pointing and vibration

  9. 3.0 Tesla breast magnetic resonance imaging in patients with nipple discharge when mammography and ultrasound fail.

    Science.gov (United States)

    Lubina, Nóra; Schedelbeck, Ulla; Roth, Anne; Weng, Andreas Max; Geissinger, Eva; Hönig, Arnd; Hahn, Dietbert; Bley, Thorsten Alexander

    2015-05-01

    To compare 3.0 Tesla breast magnetic resonance imaging (MRI) with galactography for detection of benign and malignant causes of nipple discharge in patients with negative mammography and ultrasound. We prospectively evaluated 56 breasts of 50 consecutive patients with nipple discharge who had inconspicuous mammography and ultrasound, using 3.0 Tesla breast MRI with a dedicated 16-channel breast coil, and then compared the results with galactography. Histopathological diagnoses and follow-ups were used as reference standard. Lesion size estimated on MRI was compared with the size at histopathology. Sensitivity and specificity of MRI vs. galactography for detecting pathologic findings were 95.7 % vs. 85.7 % and 69.7 % vs. 33.3 %, respectively. For the supposed concrete pathology based on MRI findings, the specificity was 67.6 % and the sensitivity 77.3 % (PPV 60.7 %, NPV 82.1 %). Eight malignant lesions were detected (14.8 %). The estimated size at breast MRI showed excellent correlation with the size at histopathology (Pearson's correlation coefficient 0.95, p Tesla is an accurate imaging test and can replace galactography in the workup of nipple discharge in patients with inconspicuous mammography and ultrasound. • Breast MRI is an excellent diagnostic tool for patients with nipple discharge. • MRI of the breast reveals malignant lesions despite inconspicuous mammography and ultrasound. • MRI of the breast has greater sensitivity and specificity than galactography. • Excellent correlation of lesion size measured at MRI and histopathology was found.

  10. Quantum Dynamics of Magnetic and Electric Dipoles and Berry's Phase

    CERN Document Server

    Furtado, C; Furtado, Claudio

    2003-01-01

    We study the quantum dynamics of neutral particle that posseses a permanent magnetic and electric dipole moments in the presence of an electromagnetic field. The analysis of this dynamics demonstrates the appearance of a quantum phase that combines the Aharonov-Casher effect and the He-Mckellar-Wilkens effect. We demonstrate that this phase is a special case of the Berry's quantum phase. A series of field configurations where this phase would be found are presented. A generalized Casella-type effect is found in one these configurations. A physical scenario for the quantum phase in an interferometric experiment is proposed.

  11. Phase-space dynamics of runaway electrons in magnetic fields

    Science.gov (United States)

    Guo, Zehua; McDevitt, Christopher J.; Tang, Xian-Zhu

    2017-04-01

    Dynamics of runaway electrons in magnetic fields are governed by the competition of three dominant physics: parallel electric field acceleration, Coulomb collision, and synchrotron radiation. Examination of the energy and pitch-angle flows reveals that the presence of local vortex structure and global circulation is crucial to the saturation of primary runaway electrons. Models for the vortex structure, which has an O-point to X-point connection, and the bump of runaway electron distribution in energy space have been developed and compared against the simulation data. Identification of these velocity-space structures opens a new venue to re-examine the conventional understanding of runaway electron dynamics in magnetic fields.

  12. Dynamical supersymmetry breaking on magnetized tori and orbifolds

    Directory of Open Access Journals (Sweden)

    Hiroyuki Abe

    2016-10-01

    Full Text Available We construct several dynamical supersymmetry breaking (DSB models within a single ten-dimensional supersymmetric Yang–Mills (SYM theory, compactified on magnetized tori with or without orbifolding. We study the case that the supersymmetry breaking is triggered by a strong dynamics of SU(NC SYM theory with NF flavors contained in the four-dimensional effective theory. We show several configurations of magnetic fluxes and orbifolds, those potentially yield, below the compactification scale, the field contents and couplings required for triggering DSB. We especially find a class of self-complete DSB models on orbifolds, where all the extra fields are eliminated by the orbifold projection and DSB successfully occurs within the given framework. Comments on some perspectives for associating the obtained DSB models with the other sectors, such as the visible sector and another hidden sector for, e.g., stabilizing moduli, are also given.

  13. Quantifying Chiral Magnetic Effect from Anomalous-Viscous Fluid Dynamics

    CERN Document Server

    Jiang, Yin; Yin, Yi; Liao, Jinfeng

    2016-01-01

    Chiral Magnetic Effect (CME) is the macroscopic manifestation of the fundamental chiral anomaly in a many-body system of chiral fermions, and emerges as anomalous transport current in the fluid dynamics framework. Experimental observation of CME is of great interest and has been reported in Dirac and Weyl semimetals. Significant efforts have also been made to search for CME in heavy ion collisions. Encouraging evidence of CME-induced charge separation in those collisions has been reported, albeit with ambiguity due to background contamination. Crucial for addressing such issue, is the need of quantitative predictions for CME signal with sophisticated modelings. In this paper we develop such a tool, the Anomalous Viscous Fluid Dynamics (AVFD) framework, which simulates the evolution of fermion currents in QGP on top of the data-validated VISHNU bulk hydrodynamic flow. With realistic initial conditions and magnetic field lifetime, the AVFD-predicted CME signal could be quantitatively consistent with measured ch...

  14. Ultrafast element-specific decoupling of magnetization dynamics in permalloy

    Energy Technology Data Exchange (ETDEWEB)

    Grychtol, Patrik [Department of Physics, JILA, University of Colorado, Boulder, Colorado 80309-0440 (United States); Institute of Solid State Research, IFF-9, Research Center Juelich, 52425, Juelich (Germany); La-O-Vorakiat, Chan; Siemens, Mark; Kapteyn, Henry; Murnane, Margaret [Department of Physics, JILA, University of Colorado, Boulder, Colorado 80309-0440 (United States); Mathias, Stefan [Department of Physics, JILA, University of Colorado, Boulder, Colorado 80309-0440 (United States); University of Kaiserslautern, Research Center OPTIMAS, 67663, Kaiserslautern (Germany); Shaw, Justin; Nembach, Hans; Silva, Tom [Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado 80305-3328 (United States); Adam, Roman; Schneider, Claus M. [Institute of Solid State Research, IFF-9, Research Center Juelich, 52425, Juelich (Germany); Eich, Steffen; Aeschlimann, Martin [University of Kaiserslautern, Research Center OPTIMAS, 67663, Kaiserslautern (Germany)

    2011-07-01

    Elucidating the dynamic behavior of complex magnetic systems far from their thermal equilibrium is a topic of utmost scientific interest. In our work, we employ soft x-ray pulses from high-harmonic-generation to probe the dynamic response of thin permalloy films during an ultrafast optically driven demagnetization process. We find that the demagnetization times for the elements Fe and Ni differ significantly, despite their strong exchange coupling in the thermodynamic equilibrium. We ascribe this difference to a breakdown of exchange interaction on the femtosecond timescale, a process that we further enhance by alloying permalloy with Cu. Our data shows that, in general, a site-specific spin environment must be considered to correctly describe ultrafast magnetization processes in compounds.

  15. Dynamical supersymmetry breaking on magnetized tori and orbifolds

    Science.gov (United States)

    Abe, Hiroyuki; Kobayashi, Tatsuo; Sumita, Keigo

    2016-10-01

    We construct several dynamical supersymmetry breaking (DSB) models within a single ten-dimensional supersymmetric Yang-Mills (SYM) theory, compactified on magnetized tori with or without orbifolding. We study the case that the supersymmetry breaking is triggered by a strong dynamics of SU (NC) SYM theory with NF flavors contained in the four-dimensional effective theory. We show several configurations of magnetic fluxes and orbifolds, those potentially yield, below the compactification scale, the field contents and couplings required for triggering DSB. We especially find a class of self-complete DSB models on orbifolds, where all the extra fields are eliminated by the orbifold projection and DSB successfully occurs within the given framework. Comments on some perspectives for associating the obtained DSB models with the other sectors, such as the visible sector and another hidden sector for, e.g., stabilizing moduli, are also given.

  16. Dynamical supersymmetry breaking on magnetized tori and orbifolds

    CERN Document Server

    Abe, Hiroyuki; Sumita, Keigo

    2016-01-01

    We construct several dynamical supersymmetry breaking (DSB) models within a single ten-dimensional supersymmetric Yang-Mills (SYM) theory, compactified on magnetized tori with or without orbifolding. We study the case that the supersymmetry breaking is triggered by a strong dynamics of $SU(N_C)$ SYM theory with $N_F$ flavors contained in the four-dimensional effective theory. We show several configurations of magnetic fluxes and orbifolds, those potentially yield, below the compactification scale, the field contents and couplings required for triggering DSB. We especially find a class of self-complete DSB models on orbifolds, where all the extra fields are eliminated by the orbifold projection and DSB successfully occurs within the given framework. Comments on some perspectives for associating the obtained DSB models with the other sectors, such as the visible sector and another hidden sector for, e.g., stabilizing moduli, are also given.

  17. Magnetic Flux Dynamics in Horizontally Cooled Superconducting Cavities

    CERN Document Server

    Martinello, M; Grassellino, A; Crawford, A C; Melnychuk, O; Romanenko, A; Sergatkov, D A

    2015-01-01

    Previous studies on magnetic flux expulsion as a function of cooling details have been performed for superconducting niobium cavities with the cavity beam axis placed parallel respect to the helium cooling flow, and findings showed that for sufficient cooling thermogradients all magnetic flux could be expelled and very low residual resistance could be achieved. In this paper we investigate the flux trapping and its impact on radio frequency surface resistance when the resonators are positioned perpendicularly to the helium cooling flow, which is representative of how superconducting radio-frequency (SRF) cavities are cooled in an accelerator. We also extend the studies to different directions of applied magnetic field surrounding the resonator. Results show that in the cavity horizontal configuration there is a different impact of the various field components on the final surface resistance, and that several parameters have to be considered to understand flux dynamics. A newly discovered phenomenon of concent...

  18. Noise-induced bifurcations in magnetization dynamics of uniaxial nanomagnets

    Energy Technology Data Exchange (ETDEWEB)

    Serpico, C., E-mail: serpico@unina.it; Perna, S.; Quercia, A. [Dipartimento di Ingegneria Elettrica e delle Tecnologie dell' Informazione, Università di Napoli “Federico II,” I-80125 Napoli (Italy); Bertotti, G. [Istituto Nazionale di Ricerca Metrologica, I-10135 Torino (Italy); D' Aquino, M. [Dipartimento di Ingegneria, Università di Napoli “Parthenope,” I-80143 Napoli (Italy); Mayergoyz, I. D. [ECE Department and UMIACS, University of Maryland, College Park, Maryland 20742 (United States)

    2015-05-07

    Stochastic magnetization dynamics in uniformly magnetized nanomagnets is considered. The system is assumed to have rotational symmetry as the anisotropy axis, the applied field, and the spin polarization are all aligned along an axis of symmetry. By appropriate integration of the Fokker-Planck equation associated to the problem, the stochastic differential equation governing the evolution of the angle between the magnetization orientation and the symmetry axis is derived. The drift terms present in this equation contain a noise-induced drift term, which, in combination with drift terms of deterministic origin, can be written as the derivative of an effective potential. Superparamagnetic-like transitions are studied in connections with the bifurcations of the effective potential as temperature and excitation conditions are varied.

  19. Molecular photoacoustic tomography of breast cancer using receptor targeted magnetic iron oxide nanoparticles as contrast agents.

    Science.gov (United States)

    Xi, Lei; Grobmyer, Stephen R; Zhou, Guangyin; Qian, Weiping; Yang, Lily; Jiang, Huabei

    2014-06-01

    In this report, we present a breast imaging technique combining high-resolution near-infrared (NIR) light induced photoacoustic tomography (PAT) with NIR dye-labeled amino-terminal fragments of urokinase plasminogen activator receptor (uPAR) targeted magnetic iron oxide nanoparticles (NIR830-ATF-IONP) for breast cancer imaging using an orthotopic mouse mammary tumor model. We show that accumulation of the targeted nanoparticles in the tumor led to photoacoustic contrast enhancement due to the high absorption of iron oxide nanoparticles (IONP). NIR fluorescence images were used to validate specific delivery of NIR830-ATF-IONP to mouse mammary tumors. We found that systemic delivery of the targeted IONP produced 4- and 10-fold enhancement in photoacoustic signals in the tumor, compared to the tumor of the mice that received non-targeted IONP or control mice. The use of targeted nanoparticles allowed imaging of tumors located as deep as 3.1 cm beneath the normal tissues. Our study indicates the potential of the combination of photoacoustic tomography and receptor-targeted NIR830-ATF-IONP as a clinical tool that can provide improved specificity and sensitivity for breast cancer detection.

  20. Modeling static and dynamic thermography of the human breast under elastic deformation

    Science.gov (United States)

    Jiang, Li; Zhan, Wang; Loew, Murray H.

    2011-01-01

    An abnormal thermogram has been shown to be a reliable indicator of increased risk of breast cancer. Numerical modeling techniques for thermography are proposed to quantify the complex relationships between the breast thermal behaviors and the underlying physiological/pathological conditions. Previous thermal modeling techniques did not account for gravity-induced elastic deformation arising from various body postures, nor did they suggest that a dynamic thermal procedure may be used to enhance clinical diagnosis. In this paper, 3D finite element method (FEM)-based thermal and elastic modeling techniques are developed to characterize comprehensively both the thermal and elastic properties of normal and tumorous breast tissues during static and dynamic thermography. In the steady state, gravity-induced breast deformation is found to cause an upper-lower asymmetric surface temperature contrast for sitting/standing up body posture, even though all the thermal and elastic properties are assumed uniform. Additionally, the tumor-induced surface temperature alterations are found to be caused primarily by shallow tumors and to be less sensitive to tumor size than to tumor depth. In the dynamic state, the breast exhibits distinctive temporal patterns that are associated with distinct thermal events: cold stress and thermal recovery induced by changes in the ambient temperature. Specifically, the tumor-induced thermal contrast shows an opposite initial change and delayed peak as compared with the deformation-induced thermal contrast. These findings are expected to provide a stronger foundation for, and greater specificity and precision in, thermographic diagnosis, and treatment of breast cancer.

  1. Single-Particle Quantum Dynamics in a Magnetic Lattice

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, Marco

    2001-02-01

    We study the quantum dynamics of a spinless charged-particle propagating through a magnetic lattice in a transport line or storage ring. Starting from the Klein-Gordon equation and by applying the paraxial approximation, we derive a Schroedinger-like equation for the betatron motion. A suitable unitary transformation reduces the problem to that of a simple harmonic oscillator. As a result we are able to find an explicit expression for the particle wavefunction.

  2. Spin dynamics of an ultra-small nanoscale molecular magnet

    Directory of Open Access Journals (Sweden)

    Ciftja Orion

    2007-01-01

    Full Text Available AbstractWe present mathematical transformations which allow us to calculate the spin dynamics of an ultra-small nanoscale molecular magnet consisting of a dimer system of classical (high Heisenberg spins. We derive exact analytic expressions (in integral form for the time-dependent spin autocorrelation function and several other quantities. The properties of the time-dependent spin autocorrelation function in terms of various coupling parameters and temperature are discussed in detail.

  3. Simulation of dynamics of a permanent magnet linear actuator

    DEFF Research Database (Denmark)

    Yatchev, Ivan; Ritchie, Ewen

    2010-01-01

    Comparison of two approaches for the simulation of the dynamic behaviour of a permanent magnet linear actuator is presented. These are full coupled model, where the electromagnetic field, electric circuit and mechanical motion problems are solved simultaneously, and decoupled model, where first...... flexibility when the actuator response is required to be estimated for different external conditions, e.g. external circuit parameters or mechanical loads....

  4. Pulsed field probe of real time magnetization dynamics in magnetic nanoparticle systems

    Science.gov (United States)

    Foulkes, T.; Syed, M.; Taplin, T.

    2015-05-01

    Magnetic nanoparticles (MNPs) are extensively used in biotechnology. These applications rely on magnetic properties that are a keen function of MNP size, distribution, and shape. Various magneto-optical techniques, including Faraday Rotation (FR), Cotton-Mouton Effect, etc., have been employed to characterize magnetic properties of MNPs. Generally, these measurements employ AC or DC fields. In this work, we describe the results from a FR setup that uses pulsed magnetic fields and an analysis technique that makes use of the entire pulse shape to investigate size distribution and shape anisotropy. The setup employs a light source, polarizing components, and a detector that are used to measure the rotation of light from a sample that is subjected to a pulsed magnetic field. This magnetic field "snapshot" is recorded alongside the intensity pulse of the sample's response. This side by side comparison yields useful information about the real time magnetization dynamics of the system being probed. The setup is highly flexible with variable control of pulse length and peak magnitude. Examining the raw data for the response of bare Fe3O4 and hybrid Au and Fe3O4 nanorods reveals interesting information about Brownian relaxation and the hydrodynamic size of these nanorods. This analysis exploits the self-referencing nature of this measurement to highlight the impact of an applied field on creating a field induced transparency for a longitudinal measurement. Possible sources for this behavior include shape anisotropy and field assisted aggregate formation.

  5. Dynamics of ferromagnetic nanowires in a rotating magnetic field

    Directory of Open Access Journals (Sweden)

    Lixin Yang

    2015-07-01

    Full Text Available Manipulating nanowires with external magnetic fields has emerged as a powerful tool in various engineering applications, which prompts an urgent need to better understand the dynamics of nanowire rotation under different control conditions. In this article, the motion of ferromagnetic nickel (Ni nanowires under a rotating magnetic field was investigated both theoretically and experimentally. The synchronous and asynchronous rotations were characterized in detail. Analytical models were developed for the major modes of motion by solving the governing equations of rotation. Particularly, a selection of theoretical formula for fluid viscous torque on nanowires of large aspect ratios was made based on the computational fluid dynamics simulation results. The comparisons of the theoretical prediction and the experimental data showed very good agreement. The effects of various system variables, such as the strength and rotating frequency of the magnetic field and the nanowire aspect ratio, were examined. Hence, the insights gained from this work can be applied to future exploration of magnetic manipulation of nanowires.

  6. Dynamics of colloidal systems of magnetic nanoparticles under influence of magnetic fields investigated by XPCS

    Energy Technology Data Exchange (ETDEWEB)

    Schavkan, Alexander

    2017-05-15

    This thesis investigates structural properties and the underlying microscopic dynamics of suspensions of α-FeOOH goethite platelets in water under the influence of magnetic fields. Goethite particles show unusual physical properties and a rich phase diagram, which makes their suspensions an object of high interest for research in the area of ''smart nanoparticles''. Five nanoparticle concentrations were chosen such that different liquid crystal phases could be studied. The suspensions of platelets of these chosen concentrations were exposed to magnetic fields of varying strength. Small angle X-ray scattering and X-ray photon correlation spectroscopy data were taken and evaluated. The appearing phases and phase transitions were studied as a function of concentration and applied magnetic field. For this purpose, order parameters, ellipticity, radial and azimuthal peak positions and widths of scattering features were investigated to clarify the structural properties in detail. For the analysis of the underlying dynamics, the relaxation rates and the shape of measured time correlation functions were evaluated. The results show that with increasing magnetic field a partial realignment of the platelets occurs. This realignment is connected to the magnetic properties of the particles. The dynamics of the corresponding phases revealed a dependence on the concentration of nanoparticles in the suspension. At a concentration of c=20 vol% the transition from the nematic to the anti-nematic phase traverses a mixed state. The nematic and anti-nematic phases show ballistic motion and very similar properties, even though a realignment of the particles from an orientation with the long axis parallel to the applied magnetic field in the nematic phase to an orientation with the long axis perpendicular to the magnetic field in the anti-nematic phase occurs. The mixed state of 20 vol%-suspension exhibits a diffusive motion of the particles and different

  7. Dynamics of Solid Body in Magnetic Suspension under Periodic Excitation

    Directory of Open Access Journals (Sweden)

    A. M. Gouskov

    2017-01-01

    Full Text Available The article studies dynamics of ferromagnetic body in hybrid magnetic suspension (HMS. The body is supposed to have one degree of freedom and a nonlinear magnetic force dependence on the current and displacement. The magnetic force induced in the HMS is divided into a passive component and an active one. Specifying the law of current variation in the coil allows us to generate nonlinear oscillations under electromagnet action. To provide periodic excitation the appropriate law of the current variation in the electromagnet coil is proposed. The mathematical model includes external periodic step-excitation. The equation of motion is formed. The scales of similarity are highlighted in the system, and the equation of motion is reduced to dimensionless form.The motion dynamics is studied numerically. The relaxation method was used to determine the periodic motions at different values of dimensionless frequency of the electromagnet excitation as well as to estimate the influence of other dimensionless parameters on the system dynamics. The amplitude-frequency curve analysis allows us to come to conclusion that the nature of system nonlinearity is rigid. Adding the external periodic step-excitation leads to the qualitative change in the nature of movement. This points to the occurrence of bifurcation.

  8. SU-E-P-14: Dosimetric Effects of Magnetic Field in MRI-Guided Radiation Therapy Delivery for Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, G; Currey, A; Li, X [Medical College of Wisconsin, Milwaukee, WI (United States)

    2015-06-15

    Purpose: MRI-guided radiation therapy (RT) delivery would be beneficial for breast irradiation. The electron return effect due to the presence of a transverse magnetic field (TMF) may cause dosimetric issues on dose on skin and at the lung-tissue interface. The purpose of this study is to investigate these issues. Methods: IMRT plans with tangential beams and VMAT plans with 200 degree arcs to cover ipsilateral breast were generated for 10 randomly selected breast cancer cases using a research planning system (Monaco, Elekta) utilizing Monte Carlo dose calculation with or without a TMF of 1.5 T. Plans were optimized to deliver uniform dose to the whole breast with an exclusion of 5 mm tissue under the skin (PTV-EVAL). All four plans for each patient were re-scaled to have the same PTV-EVAL volume to receive the same prescription dose. The skin is defined as the first 5 mm of ipsilateral-breast tissue, plus extensions in the surrounding region. Results: The presence of 1.5 T TMF resulted in (1)increased skin dose, with the mean and maximum skin dose increase of 5% and 9%, respectively; (2) similar dose homogeneity within the PTV-EVAL; (3) the slightly improved (3%) dose homogeneity in the whole breast; (4) Averages of 9 and 16% increases in V5 and V20, respectively, for ipsilateral lung; and (5) increased the mean heart dose by 34%. VMAT plans don’t improve whole breast dose uniformity as compared that to the tangential plans. Conclusion: The presence of transverse magnetic field in MRI-guided RT delivery for whole breast irradiation can Result in slightly improved dose homogeneity in the whole breast, increased dose to the ipsilateral lung, heart, and skin. Plan optimization with additional specific dose volume constraints may eliminate/reduce these dose increases. This work is partially supported by Elekta Inc.

  9. Application analysis of breast magnetic resonance imaging in occult breast cancer and breast-conserving surgery%乳腺 MRI 在隐匿性乳腺癌和保乳手术中的应用分析

    Institute of Scientific and Technical Information of China (English)

    王芹; 马行天; 石岚

    2014-01-01

    Objective: To discuss application values of breast magnetic resonance imaging (MRI) in occult breast cancer and breast-conserving surgery. Methods: Breast MRI was performed in 120 grouped patients. The examination results were analyzed and summarized. Results: In the 58 cases of occult breast cancer patients with breast MRI, 32 cases were found with breast lesions, in which 19 cases were confirmed by pathology as the original site; the diagnosis rate was 32. 7% . In the 62 cases of breast cancer being performed breast-conserving surgery with breast MRI, multiple lesions was found in 25 cases, in which 23 cases gave up breast-con-serving surgery. Conclusions: Breast MRI has a higher resolution in finding the primary lesion of occult breast cancer, and has impor-tant value in the display of breast cancers with multicentric lesions and the indication of breast-conserving surgery.%目的::探讨乳腺核磁共振成像(MRI)在隐匿性乳腺癌和保乳手术中的应用价值。方法:对120例隐匿性乳腺癌及早期患者进行 MRI 检查,对检查结果进行分析和归纳。结果:入组的58例隐匿性乳腺癌患者 MRI 检查,发现乳腺病灶32例,其中19例经病理证实为原发灶,确诊率为32.7%;入组的62例拟行保乳手术的乳腺癌患者 MRI 检查,有25例发现多中心病灶,其中23例放弃保乳手术。结论:MRI 检查对检出隐匿性乳腺癌原发灶有着有较高的分辨率,对多中心乳腺癌的显示以及明确乳腺癌的保乳适应症,有着重要的临床价值。

  10. Dynamics of resonant magnetic field penetration and plasma rotation

    Science.gov (United States)

    Ivanov, N. V.; Kakurin, A. M.

    2017-01-01

    Results of calculations and analysis of the penetration of resonant magnetic perturbations (RMP) into tokamak plasma are presented. The TEAR code used for the calculations is based on a two-fluid magnetohydrodynamics approximation that gives coupled diffusion-type equations for the magnetic flux perturbation and for plasma rotation velocities in toroidal and poloidal directions. The radial distribution of the magnetic flux perturbation is calculated taking account of an externally applied RMP and magnetic perturbation generated by an eddy current in the resistive-vacuum vessel. The decoupling of magnetic-island velocity from the velocity of plasma rotation is employed in the calculations according to available experimental evidence and corresponding theoretical understanding. The account of this decoupling, as well as of plasma rotation in the poloidal direction in addition to the toroidal one, reduces the RMP penetration threshold and accelerates the penetration process. The main attention is paid to the dependences of the RMP penetration dynamics on the simulation conditions. The simulation findings are compared with available experimental data. Some predictions of the penetration threshold values for ITER conditions are presented.

  11. Magnon-phonon interconversion in a dynamically reconfigurable magnetic material

    Science.gov (United States)

    Guerreiro, Sergio C.; Rezende, Sergio M.

    2015-12-01

    The ferrimagnetic insulator yttrium iron garnet (YIG) is an important material in the field of magnon spintronics, mainly because of its low magnetic losses. YIG also has very low acoustic losses, and for this reason the conversion of a state of magnetic excitation (magnons) into a state of lattice vibration (phonons), or vice versa, broadens its possible applications in spintronics. Since the magnetic parameters can be varied by some external action, the magnon-phonon interconversion can be tuned to perform a desired function. We present a quantum theory of the interaction between magnons and phonons in a ferromagnetic material subject to a dynamic variation of the applied magnetic field. It is shown that when the field gradient at the magnetoelastic crossover region is much smaller than a critical value, an initial elastic excitation can be completely converted into a magnetic excitation, or vice versa. This occurs with conservation of linear momentum and spin angular momentum, implying that phonons created by the conversion of magnons have spin angular momentum and carry spin current. It is shown further that if the system is initially in a quantum coherent state, its coherence properties are maintained regardless of the time dependence of the field.

  12. Autologous breast reconstruction: preoperative magnetic resonance angiography for perforator flap vessel mapping.

    Science.gov (United States)

    Agrawal, Mukta D; Thimmappa, Nanda Deepa; Vasile, Julie V; Levine, Joshua L; Allen, Robert J; Greenspun, David T; Ahn, Christina Y; Chen, Constance M; Hedgire, Sandeep S; Prince, Martin R

    2015-01-01

    Selection of a vascular pedicle for autologous breast reconstruction is time consuming and depends on visual evaluation during the surgery. Preoperative imaging of donor site for mapping the perforator artery anatomy greatly improves the efficiency of perforator selection and significantly reduces the operative time. In this article, we present our experience with magnetic resonance angiography (MRA) for perforator vessel mapping including MRA technique and interpretation. We have performed over 400 MRA examinations from August 2008 to August 2013 at our institution for preoperative imaging of donor site for mapping the perforator vessel anatomy. Using our optimized imaging protocol with blood pool magnetic resonance imaging contrast agents, multiple donor sites can be imaged in a single MRA examination. Following imaging using the postprocessing and reporting tool, we estimated incidence of commonly used perforators for autologous breast reconstruction. In our practice, anterior abdominal wall tissue is the most commonly used donor site for perforator flap breast reconstruction and deep inferior epigastric artery perforators are the most commonly used vascular pedicle. A thigh flap, based on the profunda femoral artery perforator has become the second most used flap at our institution. In addition, MRA imaging also showed evidence of metastatic disease in 4% of our patient subset. Our MRA technique allows the surgeons to confidently assess multiple donor sites for the best perforator and flap design. In conclusion, a well-performed MRA with specific postprocessing provides an accurate method for mapping perforator vessel, at the same time avoiding ionizing radiation. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  13. Breast Lesions: Correlation of Dynamic Contrast Enhancement Patterns on MR images with Tumor Angiogenesis

    Institute of Scientific and Technical Information of China (English)

    PeifangLiu; RunxianBao; YunNiu; YongYu

    2004-01-01

    OBJECTIVE To determine whether dynamic contrast-enhanced MRI features of the early -phase enhancement rate, enhancement amplitude, and signal-intensity (SI) time course are associated with the microvessel density (MVD) and vascular endothelial growth factor (VEGF) expression of malignant and benign breast lesions. METHODS Sixty patients with breast lesions, detected with physical examination or conventional mammography, were examined pre-operatively with dynamic contrast-enhanced MRI from December 1998 to June 2000. Of these 60 patients, histopathological correlation was available in 38. These 38 patients(aged 29-73 years) formed the basis of this study. SI changes during dynamic scanning were assessed quantitatively. Early-phase enhancement rate and enhancement amplitude were calculated. Time-Sl curves of the lesions were obtained and classified according to their shapes as type I (which was steady enhancement to the end of the dynamic data acquisition at 7.5rain.), type Ⅱ (plateau of SI after avid initial contrast enhancement), or type Ⅲ (washout of SI after avid initial contrast enhancement). The mean MVD and VEGF expression of the lesions were measured with immunohistochemical staining methods in all the pathologic specimens by a pathologist without knowledge of the results of the MR examination. Care was taken to ensure identical location in the plane of the MR image and pathologic specimens. The relationships among dynamic contrast-enhanced MRI features, MVD, and VEGF expression of benign and malignant breast lesions were analyzed. RESULTS Histology revealed 21 malignancies and 17 benign lesions. The mean MVD and VEGF expression for the 21 malignant lesions were significantly higher than the mean MVD and VEGF expression for the 17 benign lesions (P60%) MR early-phase enhancement rate and time-SI curve type Ⅱ or Ⅲ showed a significant association with MVD and VEGF expression. All the differences mentioned above showed statistical significance (P 0

  14. Preoperative breast magnetic resonance imaging and contralateral breast cancer occurrence among older women with ductal carcinoma in situ.

    Science.gov (United States)

    Wang, Shi-Yi; Long, Jessica B; Killelea, Brigid K; Evans, Suzanne B; Roberts, Kenneth B; Silber, Andrea; Gross, Cary P

    2016-07-01

    Although preoperative magnetic resonance imaging (MRI) can detect mammographically occult contralateral breast cancers (CBCs) among women with ductal carcinoma in situ (DCIS), the impact of MRI on the incidence of subsequent CBC events is unclear. We examined whether MRI use decreases CBC occurrences and detection of invasive disease among women who develop a CBC. Utilizing the Surveillance, Epidemiology, and End Results-Medicare dataset, we assessed overall, synchronous (cancer diagnosis), and subsequent (≥6 months after diagnosis, i.e., metachronous) CBC occurrence in women aged 67-94 years diagnosed with DCIS during 2004-2009, with follow-up through 2011. We applied a matched propensity score approach to compare the stage-specific incidence rate of CBC according to MRI use. Our sample consisted of 9166 beneficiaries, 1258 (13.7 %) of whom received preoperative MRI. After propensity score matching, preoperative MRI use was significantly associated with a higher synchronous CBC detection rate (108.6 vs. 29.7 per 1000 person-years; hazard ratio [HR] = 3.65; p clinically evident.

  15. Fat suppression techniques for obtaining high resolution dynamic contrast enhanced bilateral breast MR images at 7 tesla

    DEFF Research Database (Denmark)

    van der Velden, Tijl A; Schmitz, Alexander M Th; Gilhuijs, Kenneth G A

    2016-01-01

    OBJECTIVES: To compare water selective excitation (WSE) and Dixon fat suppression in the context of high-resolution dynamic contrast enhanced MRI of the breast at 7 tesla. METHODS: Ten healthy volunteers and one patient with a malignant breast lesion were scanned at 7 tesla. The MRI protocol...

  16. Evaluation of optimized magnetic resonance perfusion imaging scanning time window after contrast agent injection for differentiating benign and malignant breast lesions.

    Science.gov (United States)

    Dong, Jie; Wang, Dawei; Ma, Zhenshen; Deng, Guodong; Wang, Lanhua; Zhang, Jiandong

    2017-03-01

    The aim of the study was evaluate the 3.0 T magnetic resonance (MR) perfusion imaging scanning time window following contrast injection for differentiating benign and malignant breast lesions and to determine the optimum scanning time window for increased scanner usage efficiency and reduced diagnostic adverse risk factors. A total of 52 women with breast abnormalities were selected for conventional MR imaging and T1 dynamic-enhanced imaging. Quantitative parameters [volume transfer constant (Ktrans), rate constant (Kep) and extravascular extracellular volume fraction (Ve)] were calculated at phases 10, 20, 30, 40 and 50, which represented time windows at 5, 10, 15, 20 and 25 min, respectively, following injection of contrast agent. The association of the parameters at different phases with benign and malignant tumor diagnosis was analyzed. MR perfusion imaging was verified as an effective modality in the diagnosis of breast malignancies and the best scanning time window was identified: i) Values of Ktrans and Kep at all phases were statistically significant in differentiating benign and malignant tumors (P0.05); ii) values of Ve in benign tumors increased with phase number, but achieved no obvious changes at different phases in malignant tumors; iii) the optimum scanning time window of breast perfusion imaging with 3.0 T MR was between phases 10 and 30 (i.e., between 5 and 15 min after contrast agent injection). The variation trend of Ve values at different phases may serve as a diagnostic reference for differentiating benign and malignant breast abnormalities. The most efficient scanning time window was indicated to be 5 min after contrast injection, based on the observation that the Ve value only had statistical significance in diagnosis at stage 10. However, the optimal scanning time window is from 5 to 15 min following the injection of contrast agent, since that the variation trend of Ve is able to serve as a diagnostic reference.

  17. Simulations of Energetic Particles Interacting with Dynamical Magnetic Turbulence

    Science.gov (United States)

    Hussein, M.; Shalchi, A.

    2016-02-01

    We explore the transport of energetic particles in interplanetary space by using test-particle simulations. In previous work such simulations have been performed by using either magnetostatic turbulence or undamped propagating plasma waves. In the current paper we simulate for the first time particle transport in dynamical turbulence. To do so we employ two models, namely the damping model of dynamical turbulence and the random sweeping model. We compute parallel and perpendicular diffusion coefficients and compare our numerical findings with solar wind observations. We show that good agreement can be found between simulations and the Palmer consensus range for both dynamical turbulence models if the ratio of turbulent magnetic field and mean field is δB/B0 = 0.5.

  18. Diagnositc value of 3D-gradient echo dynamic contrast enhanced MRI in breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ik; Chung, Soo Young; Park, Hai Jung; Lee, Yul; Chung, Bong Wha; Shim, Jeong Won [Hallym Univ. College of Medicine, Seoul (Korea, Republic of)

    1997-10-01

    To assess the usefulness of 3D-gradient echo dynamic contrast enhanced MRI (3D-DMRI) in the diagnosis of breast cancer and to determine the most useful parameter for this diagnosis. Using a 1.0T MR unit, (Magnetom, Siemens, Erlaugen, Germany), 3D-DMRI (TR/TE=3D30/12) with Gd-DTPA was performed in 38 cases of breast cancer, 22 of fibroadenoma, and in three normal volunteers. We retrospectively evaluated the findings according to the speed on dynamic study and maximal amount of contrast enhancement during the delayed phase;we calculated the contrast index and morphology of the cancers and compared diagnostic accuracy among these three diagnostic parameters. On conventional spin-echo T1-and T2-weighted images, there was no significant difference of signal intensity between benign fibroadenoma and breast carcinoma. Rapid contrast enhancement (within one minute) was noted in 35 breast cancer lesions (92.1%), but relatively low and slow contrast enhancement (after five minutes) was noted in three such lesions (7.9%). Gradual contrast enhancement was noted in 21 lesions of fibroadenoma(95.5%), but a moderate degree of rapid contrast enhancement (from three to five minutes) was noted in the other case (7.9%). of On the delayed enhanced phase of 3D-DMRI, the maximal amount of contrast enhancement showed no significant difference between fibroadenoma and cancer. On 3D-DMRI, an irregular, spiculated border, with high contrast enhancement was noted in all cases of breast cancer, in particular, irregular thick peripheral contrast enhancement with central necrosis was noted 11cases(28.9%). For the diagnosis of breast cancer, 3D-DMRI is a useful technique. Among the diagnostic criteria of speed, maximal amount of contrast enhancement and morphology, morphologic change after contrast enhancement study was the most useful diagnostic parameter.=20.

  19. Dynamic Contrast-Enhanced Magnetic Resonance Enterography and Dynamic Contrast-Enhanced Ultrasonography in Crohn's Disease

    DEFF Research Database (Denmark)

    Wilkens, Rune; Peters, David A; Nielsen, Agnete Hedemann

    2017-01-01

    Purpose e Cross-sectional imaging methods are important for objective evaluationof small intestinal inflammationinCrohn'sdisease(CD).The primary aim was to compare relative parameters of intestinal perfusion between contrast-enhanced ultrasonography (CEUS) and dynamic contrast-enhanced magnetic...

  20. Diagnosis of breast masses from dynamic contrast-enhanced and diffusion-weighted MR: a machine learning approach.

    Directory of Open Access Journals (Sweden)

    Hongmin Cai

    Full Text Available PURPOSE: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI is increasingly used for breast cancer diagnosis as supplementary to conventional imaging techniques. Combining of diffusion-weighted imaging (DWI of morphology and kinetic features from DCE-MRI to improve the discrimination power of malignant from benign breast masses is rarely reported. MATERIALS AND METHODS: The study comprised of 234 female patients with 85 benign and 149 malignant lesions. Four distinct groups of features, coupling with pathological tests, were estimated to comprehensively characterize the pictorial properties of each lesion, which was obtained by a semi-automated segmentation method. Classical machine learning scheme including feature subset selection and various classification schemes were employed to build prognostic model, which served as a foundation for evaluating the combined effects of the multi-sided features for predicting of the types of lesions. Various measurements including cross validation and receiver operating characteristics were used to quantify the diagnostic performances of each feature as well as their combination. RESULTS: Seven features were all found to be statistically different between the malignant and the benign groups and their combination has achieved the highest classification accuracy. The seven features include one pathological variable of age, one morphological variable of slope, three texture features of entropy, inverse difference and information correlation, one kinetic feature of SER and one DWI feature of apparent diffusion coefficient (ADC. Together with the selected diagnostic features, various classical classification schemes were used to test their discrimination power through cross validation scheme. The averaged measurements of sensitivity, specificity, AUC and accuracy are 0.85, 0.89, 90.9% and 0.93, respectively. CONCLUSION: Multi-sided variables which characterize the morphological, kinetic, pathological

  1. Review of preoperative magnetic resonance imaging (MRI) in breast cancer: should MRI be performed on all women with newly diagnosed, early stage breast cancer?

    Science.gov (United States)

    Houssami, Nehmat; Hayes, Daniel F

    2009-01-01

    Randomized controlled trials have shown equivalent survival for women with early stage breast cancer who are treated with breast-conservation therapy (local excision and radiotherapy) or mastectomy. Decades of experience have demonstrated that breast-conservation therapy provides excellent local control based on defined standards of care. Magnetic resonance imaging (MRI) has been introduced in preoperative staging of the affected breast in women with newly diagnosed breast cancer because it detects additional foci of cancer that are occult on conventional imaging. The median incremental (additional) detection for MRI has been estimated as 16% in meta-analysis. In the absence of consensus on the role of preoperative MRI, we review data on its detection capability and its impact on treatment. We outline that the assumptions behind the adoption of MRI, namely that it will improve surgical planning and will lead to a reduction in re-excision surgery and in local recurrences, have not been substantiated by trials. Evidence consistently shows that MRI changes surgical management, usually from breast conservation to more radical surgery; however, there is no evidence that it improves surgical care or prognosis. Emerging data indicate that MRI does not reduce re-excision rates and that it causes false positives in terms of detection and unnecessary surgery; overall there is little high-quality evidence at present to support the routine use of preoperative MRI. Randomized controlled trials are needed to establish the clinical, psychosocial, and long-term effects of MRI and to show a related change in treatment from standard care in women newly affected by breast cancer.

  2. The value of magnetic resonance diffusion weighted imaging and dynamic contrast-enhanced MRI in the diagnosis of benign and malignant breast lesions%磁共振扩散加权成像及动态增强MRI在乳腺病变中的应用价值

    Institute of Scientific and Technical Information of China (English)

    杨晓棠; 杨继虎; 杜笑松; 张建新

    2011-01-01

    Objective To explore the relationship between the menstrual cycle and apparent diffusion coefficient(ADC) values of MR diffusion weighted imaging(DWI).To investigate the evaluation of DWI and dynamic contrast-enhanced MRI(DCE-MRI) in distinguishing benign from malignant breast lesions.Methods Thirty-four healthy, premenopausal female volunteers who had regular menstrual cycles and 96breast disease patients who proved by surgery or Needle aspiration pathology were included in the study.Of the 96 patients, there were 36 cases with 44 benign breast lesions and 60 cases with 70 malignant breast lesions.The healthy volunteers were scanned by conventional T1 weighted MRI, T2 weighted MRI and DWI once a week for 4 weeks with Siemens Sonata 1.5T MRI(b=1000s/mm2).The patients were examined by conventional MRI, DCE-MRI and DWI.DWI using Echo planar imaging technique and frequency selection suppression technology were used in DWI(b=1000 s/mm2)and fast low angle shot sequence was used in DCE-MRI.The data of DWI and DCE-MRI were sent to Leonardo workstation.Results ①ADC values of normal breast in the second week of the menstrual cycle reduced to minimum and then slowly increased, a comparison between the mean was not significant (F=1.029, P>0.05).② In DCE-MRI, type Ⅲ curve is the typical type of breast cancer, type Ⅰ and Ⅳ curve are the typical type of breast benign lesions.③When b=1000 s/mam2, the diagnostic threshold of ADC values between the benign breast lesions and malignant lesions was 1.25×10-3 mm2/s.Conclusions ADC values were less influenced by the menstrual cycle in normal breasts.The specificity and accuracy in the diagnosis of benign and maglinant breast lesions were improved with the combination of DCE-MRI and DWI.%目的 探讨月经周期对正常乳腺实质磁共振扩散加权成像(DWI)表观扩散系数(ADC)值的影响,并评价动态增强MRI(DCE-MRI)及DWI在乳腺病变鉴别诊断中的价值。方法 选取健康女性志愿者34

  3. Histopathology of breast cancer after magnetic resonance-guided high-intensity focused ultrasound and radiofrequency ablation

    NARCIS (Netherlands)

    Knuttel, Floor; Waaijer, Laurien; Merckel, LG; van den Bosch, Maurice A A J; Witkamp, Arjen J.; Deckers, Roel; van Diest, Paul J.

    AIMS: Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation and radiofrequency ablation (RFA) are being researched as possible substitutes for surgery in breast cancer patients. The histopathological appearance of ablated tissue has not been studied in great detail. This

  4. Design, analysis and control of a novel tendon-driven magnetic resonance-guided robotic system for minimally invasive breast surgery.

    Science.gov (United States)

    Jiang, Shan; Lou, Jinlong; Yang, Zhiyong; Dai, Jiansheng; Yu, Yan

    2015-09-01

    Biopsy and brachytherapy for small core breast cancer are always difficult medical problems in the field of cancer treatment. This research mainly develops a magnetic resonance imaging-guided high-precision robotic system for breast puncture treatment. First, a 5-degree-of-freedom tendon-based surgical robotic system is introduced in detail. What follows are the kinematic analysis and dynamical modeling of the robotic system, where a mathematic dynamic model is established using the Lagrange method and a lumped parameter tendon model is used to identify the nonlinear gain of the tendon-sheath transmission system. Based on the dynamical models, an adaptive proportional-integral-derivative controller with friction compensation is proposed for accurate position control. Through simulations using different sinusoidal input signals, we observe that the sinusoidal tracking error at 1/2π Hz is 0.41 mm. Finally, the experiments on tendon-sheath transmission and needle insertion performance are conducted, which show that the insertion precision is 0.68 mm in laboratory environment.

  5. Quantification of intra-fraction motion in breast radiotherapy using supine magnetic resonance imaging

    Science.gov (United States)

    van Heijst, Tristan C. F.; Philippens, Mariëlle E. P.; Charaghvandi, Ramona K.; den Hartogh, Mariska D.; Lagendijk, Jan J. W.; Desirée van den Bongard, H. J. G.; van Asselen, Bram

    2016-02-01

    In early-stage breast-cancer patients, accelerated partial-breast irradiation techniques (APBI) and hypofractionation are increasingly implemented after breast-conserving surgery (BCS). For a safe and effective radiation therapy (RT), the influence of intra-fraction motion during dose delivery becomes more important as associated fraction durations increase and targets become smaller. Current image-guidance techniques are insufficient to characterize local target movement in high temporal and spatial resolution for extended durations. Magnetic resonance imaging (MRI) can provide high soft-tissue contrast, allow fast imaging, and acquire images during longer periods. The goal of this study was to quantify intra-fraction motion using MRI scans from 21 breast-cancer patients, before and after BCS, in supine RT position, on two time scales. High-temporal 2-dimensional (2D) MRI scans (cine-MRI), acquired every 0.3 s during 2 min, and three 3D MRI scans, acquired over 20 min, were performed. The tumor (bed) and whole breast were delineated on 3D scans and delineations were transferred to the cine-MRI series. Consecutive scans were rigidly registered and delineations were transformed accordingly. Motion in sub-second time-scale (derived from cine-MRI) was generally regular and limited to a median of 2 mm. Infrequently, large deviations were observed, induced by deep inspiration, but these were temporary. Movement on multi-minute scale (derived from 3D MRI) varied more, although medians were restricted to 2.2 mm or lower. Large whole-body displacements (up to 14 mm over 19 min) were sparsely observed. The impact of motion on standard RT techniques is likely small. However, in novel hypofractionated APBI techniques, whole-body shifts may affect adequate RT delivery, given the increasing fraction durations and smaller targets. Motion management may thus be required. For this, on-line MRI guidance could be provided by a hybrid MRI/RT modality, such as the

  6. Dynamical structure of magnetized dissipative accretion flow around black holes

    Science.gov (United States)

    Sarkar, Biplob; Das, Santabrata

    2016-09-01

    We study the global structure of optically thin, advection dominated, magnetized accretion flow around black holes. We consider the magnetic field to be turbulent in nature and dominated by the toroidal component. With this, we obtain the complete set of accretion solutions for dissipative flows where bremsstrahlung process is regarded as the dominant cooling mechanism. We show that rotating magnetized accretion flow experiences virtual barrier around black hole due to centrifugal repulsion that can trigger the discontinuous transition of the flow variables in the form of shock waves. We examine the properties of the shock waves and find that the dynamics of the post-shock corona (PSC) is controlled by the flow parameters, namely viscosity, cooling rate and strength of the magnetic field, respectively. We separate the effective region of the parameter space for standing shock and observe that shock can form for wide range of flow parameters. We obtain the critical viscosity parameter that allows global accretion solutions including shocks. We estimate the energy dissipation at the PSC from where a part of the accreting matter can deflect as outflows and jets. We compare the maximum energy that could be extracted from the PSC and the observed radio luminosity values for several supermassive black hole sources and the observational implications of our present analysis are discussed.

  7. Dynamic Contrast-Enhanced MR Imaging in a Phase Ⅱ Study on Neoadjuvant Chemotherapy Combining Rh-Endostatin with Docetaxel and Epirubicin for Locally Advanced Breast Cancer

    Directory of Open Access Journals (Sweden)

    Qianxin Jia, Junqing Xu, Weifeng Jiang, Minwen Zheng, Mengqi Wei, Jianghao Chen, Ling Wang, Yi Huan

    2013-01-01

    Full Text Available Background: Anti-angiogenesis is a promising therapeutic strategy for locally advanced breast cancer. We performed this phase II trial to evaluate the anti-angiogenesis and anti-tumor effect of rh-endostatin combined with docetaxel and epirubicin in patients with locally advanced breast cancer by dynamic contrast-enhanced magnetic resonance imaging in 70 previously untreated locally advanced breast cancer patients.Methods: The study population was randomly assigned to neoadjuvant chemotherapy with docetaxel and epirubicin (neoadjuvant chemotherapy group or neoadjuvant chemotherapy combining rh-endostatin with docetaxel and epirubicin (neoadjuvant chemotherapy+rh-endostatin group. The anti-angiogenic and anti-tumor effects of both regimens were evaluated by serial dynamic contrast-enhanced magnetic resonance imaging and microvessel density measurements after final surgery.Results: The results suggested a higher clinical objective response (90.9% vs. 67.7%, P = 0.021 and greater reductions in tumor size (67.2% vs. 55.9%, P = 0.000, Ki-67 proliferation index (32.79% vs. 12.47%, P = 0.000, tumor signal enhanced ratio (64% vs. 48%, P = 0.018, and Ktrans (67% vs. 39%, P = 0.026 in neoadjuvant chemotherapy+rh-endostatin group than those in neoadjuvant chemotherapy group. In addition, the microvessel density value in the neoadjuvant chemotherapy+rh-endostatin group was significantly lower than in the neoadjuvant chemotherapy group (18.67 ± 6.53 vs. 36.05 ± 9.64, P = 0.000. Moreover, the microvessel density value was significantly correlated with Ktrans after neoadjuvant chemotherapy+rh-endostatin treatment (r=0.88, P = 0.00.Conclusions: The neoadjuvant chemotherapy+rh-endostatin treatment significantly repressed angiogenesis in locally advanced breast cancer and synergistically enhanced the anti-tumor effect of neoadjuvant chemotherapy. Serial dynamic contrast-enhanced magnetic resonance imaging data including reductions in tumor size and Ktrans

  8. Dynamic contrast-enhanced MR imaging in a phase Ⅱ study on neoadjuvant chemotherapy combining Rh-endostatin with docetaxel and epirubicin for locally advanced breast cancer.

    Science.gov (United States)

    Jia, Qianxin; Xu, Junqing; Jiang, Weifeng; Zheng, Minwen; Wei, Mengqi; Chen, Jianghao; Wang, Ling; Huan, Yi

    2013-01-01

    Anti-angiogenesis is a promising therapeutic strategy for locally advanced breast cancer. We performed this phase II trial to evaluate the anti-angiogenesis and anti-tumor effect of rh-endostatin combined with docetaxel and epirubicin in patients with locally advanced breast cancer by dynamic contrast-enhanced magnetic resonance imaging in 70 previously untreated locally advanced breast cancer patients. The study population was randomly assigned to neoadjuvant chemotherapy with docetaxel and epirubicin (neoadjuvant chemotherapy group) or neoadjuvant chemotherapy combining rh-endostatin with docetaxel and epirubicin (neoadjuvant chemotherapy+rh-endostatin group). The anti-angiogenic and anti-tumor effects of both regimens were evaluated by serial dynamic contrast-enhanced magnetic resonance imaging and microvessel density measurements after final surgery. The results suggested a higher clinical objective response (90.9% vs. 67.7%, P = 0.021) and greater reductions in tumor size (67.2% vs. 55.9%, P = 0.000), Ki-67 proliferation index (32.79% vs. 12.47%, P = 0.000), tumor signal enhanced ratio (64% vs. 48%, P = 0.018), and K(trans) (67% vs. 39%, P = 0.026) in neoadjuvant chemotherapy+rh-endostatin group than those in neoadjuvant chemotherapy group. In addition, the microvessel density value in the neoadjuvant chemotherapy+rh-endostatin group was significantly lower than in the neoadjuvant chemotherapy group (18.67 ± 6.53 vs. 36.05 ± 9.64, P = 0.000). Moreover, the microvessel density value was significantly correlated with K(trans) after neoadjuvant chemotherapy+rh-endostatin treatment (r=0.88, P = 0.00). The neoadjuvant chemotherapy+rh-endostatin treatment significantly repressed angiogenesis in locally advanced breast cancer and synergistically enhanced the anti-tumor effect of neoadjuvant chemotherapy. Serial dynamic contrast-enhanced magnetic resonance imaging data including reductions in tumor size and K(trans), could provide non-invasive evaluation for

  9. Partial volume effects in dynamic contrast magnetic resonance renal studies

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, D. Rodriguez, E-mail: drodriguez@biotronics3d.co [CVSSP, Faculty of Engineering and Physical Sciences, University of Surrey (United Kingdom); Wells, K., E-mail: k.wells@surrey.ac.u [CVSSP, Faculty of Engineering and Physical Sciences, University of Surrey (United Kingdom); Diaz Montesdeoca, O., E-mail: o.diaz.montesdeoca@gmail.co [EUITT, Universidad de Las Palmas de Gran Canaria (Spain); Moran Santana, A. [EUITT, Universidad de Las Palmas de Gran Canaria (Spain); Mendichovszky, I.A., E-mail: iosifm@hotmail.co [Radiology and Physics Unit, UCL Institute of Child Health, London WC1N 1EH (United Kingdom); Gordon, I., E-mail: i.gordon@ich.ucl.ac.u [Radiology and Physics Unit, UCL Institute of Child Health, London WC1N 1EH (United Kingdom)

    2010-08-15

    This is the first study of partial volume effect in quantifying renal function on dynamic contrast enhanced magnetic resonance imaging. Dynamic image data were acquired for a cohort of 10 healthy volunteers. Following respiratory motion correction, each voxel location was assigned a mixing vector representing the 'overspilling' contributions of each tissue due to the convolution action of the imaging system's point spread function. This was used to recover the true intensities associated with each constituent tissue. Thus, non-renal contributions from liver, spleen and other surrounding tissues could be eliminated from the observed time-intensity curves derived from a typical renal cortical region of interest. This analysis produced a change in the early slope of the renal curve, which subsequently resulted in an enhanced glomerular filtration rate estimate. This effect was consistently observed in a Rutland-Patlak analysis of the time-intensity data: the volunteer cohort produced a partial volume effect corrected mean enhancement of 36% in relative glomerular filtration rate with a mean improvement of 7% in r{sup 2} fitting of the Rutland-Patlak model compared to the same analysis undertaken without partial volume effect correction. This analysis strongly supports the notion that dynamic contrast enhanced magnetic resonance imaging of kidneys is substantially affected by the partial volume effect, and that this is a significant obfuscating factor in subsequent glomerular filtration rate estimation.

  10. Diagnostic Efficacy of All Series of Dynamic Contrast Enhanced Breast MR Images Using Gradient Vector Flow (GVF Segmentation and Novel Border Feature Extraction for Differentiation Between Malignant

    Directory of Open Access Journals (Sweden)

    L. Bahreini

    2010-12-01

    Full Text Available Background/Objective: To discriminate between malignant and benign breast lesions;"nconventionally, the first series of Breast Subtraction Dynamic Contrast-Enhanced Magnetic"nResonance Imaging (BS DCE-MRI images are used for quantitative analysis. In this study, we"ninvestigated whether using all series of these images could provide us with more diagnostic"ninformation."nPatients and Methods: This study included 60 histopathologically proven lesions. The steps of"nthis study were as follows: selecting the regions of interest (ROI, segmentation using Gradient"nVector Flow (GVF snake for the first time, defining new feature sets, using artificial neural network"n(ANN for optimal feature set selection, evaluation using receiver operating characteristic (ROC"nanalysis."nResults: The results showed GVF snake method correctly segmented 95.3% of breast lesion"nborders at the overlap threshold of 0.4. The first classifier which used the optimal feature set"nextracted only from the first series of BS DCE-MRI images achieved an area under the curve"n(AUC of 0.82, specificity of 60% at sensitivity of 81%. The second classifier which used the same"noptimal feature set but was extracted from all five series of these images achieved an AUC of"n0.90, specificity of 79% at sensitivity of 81%."nConclusion: The result of GVF snake segmentation showed that it could make an accurate"nsegmentation in the borders of breast lesions. According to this study, using all five series of BS"nDCE-MRI images could provide us with more diagnostic information about the breast lesion and"ncould improve the performance of breast lesion classifiers in comparison with using the first"nseries alone.

  11. Kinks and Rotons in a Magnetic Cactus: Dynamical Phyllotaxis.

    Science.gov (United States)

    Nisoli, Cristiano; Monroe Gabor, Nathaniel; Crespi, Vincent Henry; Decatur Maynard, Julian

    2004-03-01

    The disposition of the leaves on a stem, spines on a cactus, seeds in a sunflower and other self-organized arrangements of repeated units in plant morphology, are denoted as phyllotaxis. Phyllotactic patterns are also found in polypeptide chains, cells of Bernard convection, and flux lattices in layered superconductors. Here we describe a "magnetic cactus," a model of interacting magnetic dipoles disposed along a cylindrical stem, based on the mechanical theory of phyllotaxis proposed by S. L. Levitov (1991). While the appearance of phyllotactic patterns in the static properties is well predicted by current theory, the dynamics bring new physics beyond that possible in biological systems: we demonstrate the formation and propagation of domain walls between stable structures, the number-theoretical properties that regulate their vibrational spectra, and show the appearence of what to our knowledge is the first example of classical rotons.

  12. Fast domain wall dynamics in amorphous and nanocrystalline magnetic microwires

    Energy Technology Data Exchange (ETDEWEB)

    Varga, R., E-mail: rvarga@upjs.sk [Institute of Physics, Faculty of Science, UPJS, Park Angelinum 9, 041 54, Kosice (Slovakia); Klein, P.; Richter, K. [Institute of Physics, Faculty of Science, UPJS, Park Angelinum 9, 041 54, Kosice (Slovakia); Zhukov, A. [Dept. Fisica de Materiales, Fac. Quimica, UPV/EHU, San Sebastian (Spain); Vazquez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Ines de la Cruz 3, 28049 Cantoblanco, Madrid (Spain)

    2012-10-15

    We have studied the effect of thermal treatment on the domain wall dynamics of FeSiB and FeCoMoB microwires. It was shown that annealing in transversal magnetic field increases the domain wall mobility as well as the domain wall velocity. Annealing under the tensile stress hinders the appearance of the monodomain structure but application of tensile stress leads to the magnetic bistability having the domain wall mobility twice higher that in as-cast state. Further increase of the tensile stress reduces the domain wall mobility but the domain wall velocity increases as a result of the decrease of critical propagation field. Annealing of the FeCoMoB microwire by Joule heating leads to introduction of the circular anisotropy that favors the vortex domain wall. Such treatment increases the domain wall mobility as well as the maximum domain wall velocity.

  13. CE-Magnetic Resonance mammography for the evaluation of the contralateral breast in patients with diagnosed breast cancer; Ruolo della Risonanza Magnetica con Gd-BOPTA nella valutazione della mammella controlaterale in pazienti con tumore recentemente diagnosticato

    Energy Technology Data Exchange (ETDEWEB)

    Pediconi, Federica; Venditti, Fiammetta; Padula, Simona; Roselli, Antonella; Moriconi, Enrica; Catalano, Carlo; Passariello, Roberto [La Sapienza Univ., Roma (Italy). Dipartimento di scienze radiologiche; Giacomelli, Laura [La Sapienza Univ., Roma (Italy). Dipartimento di scienze chirurgiche

    2005-07-15

    Purpose. To evaluate the role of contrast-enhanced Magnetic Resonance Mammography (MRM) in the evaluation of the contralateral breast in patients with recently diagnosed breast cancer. Materials and methods. Fifty patients with proved unilateral breast cancer, with a negative contralateral breast at physical examination, ultrasound and mammography, were studied with a 1.5 T magnet (Siemens, Vision Plus, Germany). A bilateral breast surface coil was used. Dynamic 3D Flash T1-weighted sequences were acquired in the axial plane before and 0, 2, 4, 6 and 8 minutes after the administration of 0.1 mmol/kg of Gd-BOPTA at a flow rate of 2 ml/s followed by 10 ml of saline. The level of suspicion was reported on a scale from 0 to 5 following the BI-RADS classification, based on lesion morphology and kinetic features. The results were compared with the histological findings after biopsy or surgery. Results. Fourteen out of 50 patients (28%) had contralateral lesions identified on MRM. Biopsy was performed in four of them for suspicious lesions (BI-RADS 4) while 10 patients underwent surgery because of highly suggestive malignant lesions (BI-RADS 5). Histology diagnosed three fibroadenomas, 5 ductal carcinoma in situ, 2 lobular carcinomas in situ, 3 invasive ductal carcinomas and 1 invasive lobular carcinoma. Contrast enhanced MRM yielded no false negative and three false positives. Conclusions. Our results demonstrate a very good accuracy of Magnetic Resonance Mammography in the detection of synchronous contralateral cancer in patients with newly diagnosed breast cancer. Therefore, contrast-enhanced MRM could be introduced to screen patients with proven breast cancer before they under-go surgery. [Italian] Scopo. Definire il ruolo della Risonanza Magnetica nella valutazione della mammella contro laterale in pazienti con tumore della mammella recentemente diagnosticato. Materiale e metodi. Cinquanta pazienti con tumore monolaterale della mammella e mammella controlaterale

  14. Risks of Breast Cancer Screening

    Science.gov (United States)

    ... of dying from breast cancer. MRI (magnetic resonance imaging) in women with a high risk of breast ... a mammogram , the breast is placed between 2 plates that are pressed together. Pressing the breast helps ...

  15. Quantitative 3D breast magnetic resonance imaging fibroglandular tissue analysis and correlation with qualitative assessments: a feasibility study.

    Science.gov (United States)

    Ha, Richard; Mema, Eralda; Guo, Xiaotao; Mango, Victoria; Desperito, Elise; Ha, Jason; Wynn, Ralph; Zhao, Binsheng

    2016-04-01

    The amount of fibroglandular tissue (FGT) has been linked to breast cancer risk based on mammographic density studies. Currently, the qualitative assessment of FGT on mammogram (MG) and magnetic resonance imaging (MRI) is prone to intra and inter-observer variability. The purpose of this study is to develop an objective quantitative FGT measurement tool for breast MRI that could provide significant clinical value. An IRB approved study was performed. Sixty breast MRI cases with qualitative assessment of mammographic breast density and MRI FGT were randomly selected for quantitative analysis from routine breast MRIs performed at our institution from 1/2013 to 12/2014. Blinded to the qualitative data, whole breast and FGT contours were delineated on T1-weighted pre contrast sagittal images using an in-house, proprietary segmentation algorithm which combines the region-based active contours and a level set approach. FGT (%) was calculated by: [segmented volume of FGT (mm(3))/(segmented volume of whole breast (mm(3))] ×100. Statistical correlation analysis was performed between quantified FGT (%) on MRI and qualitative assessments of mammographic breast density and MRI FGT. There was a significant positive correlation between quantitative MRI FGT assessment and qualitative MRI FGT (r=0.809, n=60, Pqualitative MRI FGT assessment and mammographic density assessment (r=0.725, n=60, Pqualitative assessment categories of FGT correlated with the calculated mean quantitative FGT (%) of 4.61% (95% CI, 0-12.3%), 8.74% (7.3-10.2%), 18.1% (15.1-21.1%), 37.4% (29.5-45.3%). Quantitative measures of FGT (%) were computed with data derived from breast MRI and correlated significantly with conventional qualitative assessments. This quantitative technique may prove to be a valuable tool in clinical use by providing computer generated standardized measurements with limited intra or inter-observer variability.

  16. Electric-field-driven dynamics of magnetic domain walls in magnetic nanowires patterned on ferroelectric domains

    Science.gov (United States)

    Van de Wiele, Ben; Leliaert, Jonathan; Franke, Kévin J. A.; van Dijken, Sebastiaan

    2016-03-01

    Strong coupling of magnetic domain walls onto straight ferroelastic boundaries of a ferroelectric layer enables full and reversible electric-field control of magnetic domain wall motion. In this paper, the dynamics of this new driving mechanism is analyzed using micromagnetic simulations. We show that transverse domain walls with a near-180° spin structure are stabilized in magnetic nanowires and that electric fields can move these walls with high velocities. Above a critical velocity, which depends on material parameters, nanowire geometry and the direction of domain wall motion, the magnetic domain walls depin abruptly from the ferroelastic boundaries. Depinning evolves either smoothly or via the emission and annihilation of a vortex or antivortex core (Walker breakdown). In both cases, the magnetic domain wall slows down after depinning in an oscillatory fashion and eventually comes to a halt. The simulations provide design rules for hybrid ferromagnetic-ferroelectric domain-wall-based devices and indicate that material disorder and structural imperfections only influence Walker-breakdown-like depinning at high domain wall velocities.

  17. Dynamics of Magnetized Plasma Jets and Bubbles Launched into a Background Magnetized Plasma

    Science.gov (United States)

    Wallace, B.; Zhang, Y.; Fisher, D. M.; Gilmore, M.

    2016-10-01

    The propagation of dense magnetized plasma, either collimated with mainly azimuthal B-field (jet) or toroidal with closed B-field (bubble), in a background plasma occurs in a number of solar and astrophysical cases. Such cases include coronal mass ejections moving in the background solar wind and extragalactic radio lobes expanding into the extragalactic medium. Understanding the detailed MHD behavior is crucial for correctly modeling these events. In order to further the understanding of such systems, we are investigating the injection of dense magnetized jets and bubbles into a lower density background magnetized plasma using a coaxial plasma gun and a background helicon or cathode plasma. In both jet and bubble cases, the MHD dynamics are found to be very different when launched into background plasma or magnetic field, as compared to vacuum. In the jet case, it is found that the inherent kink instability is stabilized by velocity shear developed due to added magnetic tension from the background field. In the bubble case, rather than directly relaxing to a minimum energy Taylor state (spheromak) as in vacuum, there is an expansion asymmetry and the bubble becomes Rayleigh-Taylor unstable on one side. Recent results will be presented. Work supported by the Army Research Office Award No. W911NF1510480.

  18. Design and validation of magnetic particle spectrometer for characterization of magnetic nanoparticle relaxation dynamics

    Directory of Open Access Journals (Sweden)

    Nicolas Garraud

    2017-05-01

    Full Text Available The design and validation of a magnetic particle spectrometer (MPS system used to study the linear and nonlinear behavior of magnetic nanoparticle suspensions is presented. The MPS characterizes the suspension dynamic response, both due to relaxation and saturation effects, which depends on the magnetic particles and their environment. The system applies sinusoidal excitation magnetic fields varying in amplitude and frequency and can be configured for linear measurements (1 mT at up to 120 kHz and nonlinear measurements (50 mT at up to 24 kHz. Time-resolved data acquisition at up to 4 MS/s combined with hardware and software-based signal processing allows for wide-band measurements up to 50 harmonics in nonlinear mode. By cross-calibrating the instrument with a known sample, the instantaneous sample magnetization can be quantitatively reconstructed. Validation of the two MPS modes are performed for iron oxide and cobalt ferrite suspensions, exhibiting Néel and Brownian relaxation, respectively.

  19. Dust formation and dynamic in magnetized and non-magnetized microwave discharge

    Science.gov (United States)

    Ouaras, Karim; Lombardi, Guillaume; Hassouni, Khaled

    2016-09-01

    Dusty plasmas studies are conducted for several decades to answer to various issues from microelectronic, nanotechnology, astrophysics and thermonuclear fusion devices. These studies are usually conducted in RF discharges at low pressure in which the major physics concerning dust formation mechanisms and dynamic is now well known. In our case, we focus on dust formation and dynamic in (i) microwave plasma under typical pressure conditions of RF discharges (50 Pa) and (ii) in magnetized (ECR: Electron Cyclotron Resonance) microwave plasma under very low pressure condition (0.1 to 1 Pa). The aim of this study is not only for fundamental purpose but also for respond to some issues concerning dust in fusion devices. Thus, we investigate the dust formation mechanisms and dynamic using laser extinction method and laser light scattering imaging coupling with SEM imaging in hydrocarbon plasma and with PVD system with using tungsten target (according to fusion device). We observed that dust formation occurs even if the very low pressure conditions are generally not suitable for nucleation growth in gas phase (the influence of the magnetic field will be discussed). We will also discuss about the particular dust dynamic behavior in microwave discharge in comparison with RF discharge.

  20. Magnetic resonance imaging and mammographic appearance of dermatofibrosarcoma protuberans in a male breast: a case report and literature review

    Directory of Open Access Journals (Sweden)

    Chen Xin

    2009-06-01

    Full Text Available Abstract Introduction Dermatofibrosarcoma protuberans is a rare low-grade soft tissue neoplasm with trunk and extremities being the most common sites of involvement. We report a rare case of male breast with dermatofibrosarcoma protuberans and its imaging features. To our knowledge the imaging appearance of dermatofibrosarcoma protuberans of the breast has never been reported in the literature. Case presentation We report the imaging appearance of dermatofibrosarcoma protuberans on the breast of a 41-year-old Chinese man who initially presented with a palpable lump. A mammogram showed two lesions, one with well circumscribed and the other with an ill defined border, in his right breast. Conventional magnetic resonance imaging was performed and showed the well defined larger lesion with mild central hypointensity while the smaller lesion had an irregular border. Both lesions were well characterized on the fat-suppressed sequences. Conclusions Dermatofibrosarcoma protuberans is a rare soft tissue sarcoma and its occurrence on the breast is even rarer. Mammography and magnetic resonance imaging can help in characterizing the lesion and localizing the lesion for further diagnostic evaluation and surgical planning.

  1. Voltage-induced magnetization dynamics in CoFeB/MgO/CoFeB magnetic tunnel junctions

    Science.gov (United States)

    Miura, Katsuya; Yabuuchi, Shin; Yamada, Masaki; Ichimura, Masahiko; Rana, Bivas; Ogawa, Susumu; Takahashi, Hiromasa; Fukuma, Yasuhiro; Otani, Yoshichika

    2017-01-01

    Recent progress in magnetic tunnel junctions (MTJs) with a perpendicular easy axis consisting of CoFeB and MgO stacking structures has shown that magnetization dynamics are induced due to voltage-controlled magnetic anisotropy (VCMA), which will potentially lead to future low-power-consumption information technology. For manipulating magnetizations in MTJs by applying voltage, it is necessary to understand the coupled magnetization motion of two magnetic (recording and reference) layers. In this report, we focus on the magnetization motion of two magnetic layers in MTJs consisting of top layers with an in-plane easy axis and bottom layers with a perpendicular easy axis, both having perpendicular magnetic anisotropy. According to rectified voltage (Vrec) measurements, the amplitude of the magnetization motion depends on the initial angles of the magnetizations with respect to the VCMA direction. Our numerical simulations involving the micromagnetic method based on the Landau-Lifshitz-Gilbert equation of motion indicate that the magnetization motion in both layers is induced by a combination of VCMA and transferred angular momentum, even though the magnetic easy axes of the two layers are different. Our study will lead to the development of voltage-controlled MTJs having perpendicular magnetic anisotropy by controlling the initial angle between magnetizations and VCMA directions. PMID:28209976

  2. Voltage-induced magnetization dynamics in CoFeB/MgO/CoFeB magnetic tunnel junctions

    Science.gov (United States)

    Miura, Katsuya; Yabuuchi, Shin; Yamada, Masaki; Ichimura, Masahiko; Rana, Bivas; Ogawa, Susumu; Takahashi, Hiromasa; Fukuma, Yasuhiro; Otani, Yoshichika

    2017-02-01

    Recent progress in magnetic tunnel junctions (MTJs) with a perpendicular easy axis consisting of CoFeB and MgO stacking structures has shown that magnetization dynamics are induced due to voltage-controlled magnetic anisotropy (VCMA), which will potentially lead to future low-power-consumption information technology. For manipulating magnetizations in MTJs by applying voltage, it is necessary to understand the coupled magnetization motion of two magnetic (recording and reference) layers. In this report, we focus on the magnetization motion of two magnetic layers in MTJs consisting of top layers with an in-plane easy axis and bottom layers with a perpendicular easy axis, both having perpendicular magnetic anisotropy. According to rectified voltage (Vrec) measurements, the amplitude of the magnetization motion depends on the initial angles of the magnetizations with respect to the VCMA direction. Our numerical simulations involving the micromagnetic method based on the Landau-Lifshitz-Gilbert equation of motion indicate that the magnetization motion in both layers is induced by a combination of VCMA and transferred angular momentum, even though the magnetic easy axes of the two layers are different. Our study will lead to the development of voltage-controlled MTJs having perpendicular magnetic anisotropy by controlling the initial angle between magnetizations and VCMA directions.

  3. High Dynamic Range Processing for Magnetic Resonance Imaging

    Science.gov (United States)

    Sukerkar, Preeti A.; Meade, Thomas J.

    2013-01-01

    Purpose To minimize feature loss in T1- and T2-weighted MRI by merging multiple MR images acquired at different TR and TE to generate an image with increased dynamic range. Materials and Methods High Dynamic Range (HDR) processing techniques from the field of photography were applied to a series of acquired MR images. Specifically, a method to parameterize the algorithm for MRI data was developed and tested. T1- and T2-weighted images of a number of contrast agent phantoms and a live mouse were acquired with varying TR and TE parameters. The images were computationally merged to produce HDR-MR images. All acquisitions were performed on a 7.05 T Bruker PharmaScan with a multi-echo spin echo pulse sequence. Results HDR-MRI delineated bright and dark features that were either saturated or indistinguishable from background in standard T1- and T2-weighted MRI. The increased dynamic range preserved intensity gradation over a larger range of T1 and T2 in phantoms and revealed more anatomical features in vivo. Conclusions We have developed and tested a method to apply HDR processing to MR images. The increased dynamic range of HDR-MR images as compared to standard T1- and T2-weighted images minimizes feature loss caused by magnetization recovery or low SNR. PMID:24250788

  4. High dynamic range processing for magnetic resonance imaging.

    Directory of Open Access Journals (Sweden)

    Andy H Hung

    Full Text Available To minimize feature loss in T1- and T2-weighted MRI by merging multiple MR images acquired at different TR and TE to generate an image with increased dynamic range.High Dynamic Range (HDR processing techniques from the field of photography were applied to a series of acquired MR images. Specifically, a method to parameterize the algorithm for MRI data was developed and tested. T1- and T2-weighted images of a number of contrast agent phantoms and a live mouse were acquired with varying TR and TE parameters. The images were computationally merged to produce HDR-MR images. All acquisitions were performed on a 7.05 T Bruker PharmaScan with a multi-echo spin echo pulse sequence.HDR-MRI delineated bright and dark features that were either saturated or indistinguishable from background in standard T1- and T2-weighted MRI. The increased dynamic range preserved intensity gradation over a larger range of T1 and T2 in phantoms and revealed more anatomical features in vivo.We have developed and tested a method to apply HDR processing to MR images. The increased dynamic range of HDR-MR images as compared to standard T1- and T2-weighted images minimizes feature loss caused by magnetization recovery or low SNR.

  5. 3.0 Tesla breast magnetic resonance imaging in patients with nipple discharge when mammography and ultrasound fail

    Energy Technology Data Exchange (ETDEWEB)

    Lubina, Nora; Schedelbeck, Ulla; Weng, Andreas Max; Hahn, Dietbert; Bley, Thorsten Alexander [University of Wuerzburg, Department of Diagnostic and Interventional Radiology, Wuerzburg (Germany); Roth, Anne [Centre of Radiology Wuerzburg, Wuerzburg (Germany); Geissinger, Eva [University of Wuerzburg, Institute of Pathology, Wuerzburg (Germany); Hoenig, Arnd [Catholic Clinical Centre Mainz, Department of Obstetrics and Gynecology, Mainz (Germany)

    2015-05-01

    To compare 3.0 Tesla breast magnetic resonance imaging (MRI) with galactography for detection of benign and malignant causes of nipple discharge in patients with negative mammography and ultrasound. We prospectively evaluated 56 breasts of 50 consecutive patients with nipple discharge who had inconspicuous mammography and ultrasound, using 3.0 Tesla breast MRI with a dedicated 16-channel breast coil, and then compared the results with galactography. Histopathological diagnoses and follow-ups were used as reference standard. Lesion size estimated on MRI was compared with the size at histopathology. Sensitivity and specificity of MRI vs. galactography for detecting pathologic findings were 95.7 % vs. 85.7 % and 69.7 % vs. 33.3 %, respectively. For the supposed concrete pathology based on MRI findings, the specificity was 67.6 % and the sensitivity 77.3 % (PPV 60.7 %, NPV 82.1 %). Eight malignant lesions were detected (14.8 %). The estimated size at breast MRI showed excellent correlation with the size at histopathology (Pearson's correlation coefficient 0.95, p < 0.0001). MRI of the breast at 3.0 Tesla is an accurate imaging test and can replace galactography in the workup of nipple discharge in patients with inconspicuous mammography and ultrasound. (orig.)

  6. Preoperative diagnosis of breast diseases by dynamic MR mammography. Cut off point establishment for signal intensity ratio

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Juji; Nagata, Takayasu; Kawagoe, Hajime; Tachibana, Susumu; Kajima, Toshihiko; Hoshino, Mutsuo [Ibi General Hospital, Gifu (Japan); Uno, Takashi; Shimokawa, Kuniyasu

    1997-12-01

    We have revealed that a dynamic study of the breast using MR imaging technique can estimate objectively benign-malignant differentiative diagnosis. Subjects were 41 cases of breast lesion, including 13 cases of breast cancer, 21 cases of mastopathy, six cases of fibroadenoma and one case of intraductal papillomatosis and the results of them were investigated in comparison with histopathological diagnosis. As so the method, we drew up time-signal intensity ratio curve plotting signal intensity ratio at each 30 second of dynamic MR mammography after Gd-DTPA administration. We found a especially high significant difference between cancer and mastopathy, within 90 second after Gd-DTPA administration (p=0.0000). Still more, we established cut off point concerning with establishment of 95% confidence interval, that is, at 30 second after Gd-DTPA administration of point equivalent 1.53 at 60 second equivalent 2.00, at 90 second equivalent 2.47, and about this estimating maneuver using the cut off point we named Dynamic ratio method. We can estimate preoperatively not only benign-malignant differentiative diagnosis with breast tumor, but also neighboring infiltration and lymph node metastasis of breast cancer using this Dynamic ratio method. Over again, Dynamic ratio method provides fine information to preoperative decision of resecting region for breast conserving surgery. The efficiency of this method is sensitivity=92.3%, specificity=89.3% and positive predictive value=80.0%. (author)

  7. Biosensor based on measurements of the clustering dynamics of magnetic particles

    DEFF Research Database (Denmark)

    2014-01-01

    Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample.......Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample....

  8. Dynamic modularity in protein interaction networks predicts breast cancer outcome

    DEFF Research Database (Denmark)

    Taylor, Ian W; Linding, Rune; Warde-Farley, David

    2009-01-01

    Changes in the biochemical wiring of oncogenic cells drives phenotypic transformations that directly affect disease outcome. Here we examine the dynamic structure of the human protein interaction network (interactome) to determine whether changes in the organization of the interactome can be used...

  9. The diagnosis of silicone breast-implant rupture: clinical findings compared with findings at magnetic resonance imaging

    DEFF Research Database (Denmark)

    Hölmich, Lisbet Rosenkrantz; Fryzek, Jon P; Kjøller, Kim;

    2005-01-01

    The objective was to evaluate the usefulness of clinical examination in the evaluation of breast-implant integrity, using the diagnosis at magnetic resonance imaging (MRI) as the "gold standard." Fifty-five women with 109 implants underwent a breast examination either just before or shortly after...... an MRI examination. Twenty-four of 109 implants were clinically diagnosed with possible rupture or rupture. Eighteen of the 24 implants were ruptured according to the MRI examination (75%). Eighty-five implants were clinically classified as intact, and 43 of these were actually ruptured at MRI (51...

  10. Resonant magnetic perturbation effect on tearing mode dynamics

    Science.gov (United States)

    Frassinetti, L.; Olofsson, K. E. J.; Brunsell, P. R.; Drake, J. R.

    2010-03-01

    The effect of a resonant magnetic perturbation (RMP) on the tearing mode (TM) dynamics is experimentally studied in the EXTRAP T2R device. EXTRAP T2R is equipped with a set of sensor coils and active coils connected by a digital controller allowing a feedback control of the magnetic instabilities. The recently upgraded feedback algorithm allows the suppression of all the error field harmonics but keeping a selected harmonic to the desired amplitude, therefore opening the possibility of a clear study of the RMP effect on the corresponding TM. The paper shows that the RMP produces two typical effects: (1) a weak oscillation in the TM amplitude and a modulation in the TM velocity or (2) a strong modulation in the TM amplitude and phase jumps. Moreover, the locking mechanism of a TM to a RMP is studied in detail. It is shown that before the locking, the TM dynamics is characterized by velocity modulation followed by phase jumps. Experimental results are reasonably explained by simulations obtained with a model.

  11. Dust Particle Dynamics in The Presence of Highly Magnetized Plasmas

    Science.gov (United States)

    Lynch, Brian; Konopka, Uwe; Thomas, Edward; Merlino, Robert; Rosenberg, Marlene

    2016-10-01

    Complex plasmas are four component plasmas that contain, in addition to the usual electrons, ions, and neutral atoms, macroscopic electrically charged (nanometer to micrometer) sized ``dust'' particles. These macroscopic particles typically obtain a net negative charge due to the higher mobility of electrons compared to that of ions. Because the electrons, ions, and dust particles are charged, their dynamics may be significantly modified by the presence of electric and magnetic fields. Possible consequences of this modification may be the charging rate and the equilibrium charge. For example, in the presence of a strong horizontal magnetic field (B >1 Tesla), it may be possible to observe dust particle gx B deflection and, from that deflection, determine the dust grain charge. In this poster, we present recent data from performing multiple particle dropping experiments to characterize the g x B deflection in the Magnetized Dusty Plasma Experiment (MDPX). This work is supported by funding from the U. S. Department of Energy Grant Number DE - SC0010485 and the NASA/Jet Propulsion Laboratory, JPL-1543114.

  12. Magnetization dynamics in rare earth doped NiFe films

    Energy Technology Data Exchange (ETDEWEB)

    Kiessling, Matthias; Woltersdorf, Georg; Back, Christian [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D- 93040 Regensburg (Germany); Thiele, Jan-Ulrich; Schabes, Manfred [Hitachi Global Storage Technologies, 3403 Yerba Buena Road, San Jose, CA 95135 (United States)

    2007-07-01

    The influence of rare earth dopants on the damping parameter and the resulting possibility to control this parameter were investigated. In our experiments NiFe films were doped with Dysprosium, Holmium, Terbium, and Gadolinium. The magnetization dynamics of these rare earth doped films was mainly studied by means of ferromagnetic resonance (FMR) and network-analyzer ferromagnetic resonance. It is demonstrated that the doping of a NiFe film by a small amount of rare earth elements (Holmium, Terbium and Dysprosium) greatly effects its magnetic relaxation rate. This additional damping is proportional to the doping level. Compared to the pure NiFe film it is possible to increase the damping parameter of the magnetic film by two orders of magnitude. On the other hand Gadolinium as a dopant has no influence on the damping parameter. For small dopant concentrations the in and out-of-plane FMR measurements at various frequencies can be well described by the same damping parameter. This is expected for the Gilbert damping term in the equation of motion. Therefore the increased damping can be attributed to an increased rate of transfer of angular momentum from the spin system to the lattice.

  13. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Adelnia, Fatemeh; Lascialfari, Alessandro [Dipartimento di Fisica, Università degli Studi di Milano and INSTM, Milano (Italy); Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy); Mariani, Manuel [Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna (Italy); Ammannato, Luca; Caneschi, Andrea; Rovai, Donella [Dipartimento di Chimica, Università degli Studi di Firenze and INSTM, Firenze (Italy); Winpenny, Richard; Timco, Grigore [School of Chemistry, The University of Manchester, Manchester (United Kingdom); Corti, Maurizio, E-mail: maurizio.corti@unipv.it; Borsa, Ferdinando [Dipartimento di Fisica, Università degli Studi di Pavia and INSTM, Pavia (Italy)

    2015-05-07

    We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ring and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.

  14. Assessment of three different software systems in the evaluation of dynamic MRI of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, K.D. [Department of Radiology, Stavanger University Hospital, Postbox 8100, Stavanger (Norway)], E-mail: kurk@sus.no; Steinhaus, D. [Institute of Daignostic Radiology, Duesseldorf University Hospital, Moorenstr. 5, 40225 Duesseldorf (Germany)], E-mail: Daniele.Steinhaus@med.uni-duesseldorf.de; Klar, V. [Institute of Daignostic Radiology, Duesseldorf University Hospital, Moorenstr. 5, 40225 Duesseldorf (Germany)], E-mail: verena.klar@uni-duesseldorf.de; Cohnen, M. [Institute of Daignostic Radiology, Duesseldorf University Hospital, Moorenstr. 5, 40225 Duesseldorf (Germany)], E-mail: cohnen@med.uni-duesseldorf.de; Wittsack, H.J. [Institute of Daignostic Radiology, Duesseldorf University Hospital, Moorenstr. 5, 40225 Duesseldorf (Germany)], E-mail: wittsack@uni-duesseldorf.de; Saleh, A. [Institute of Daignostic Radiology, Duesseldorf University Hospital, Moorenstr. 5, 40225 Duesseldorf (Germany)], E-mail: saleh@uni-duesseldorf.de; Moedder, U. [Institute of Daignostic Radiology, Duesseldorf University Hospital, Moorenstr. 5, 40225 Duesseldorf (Germany)], E-mail: moedder@med.uni-duesseldorf.de; Blondin, D. [Institute of Daignostic Radiology, Duesseldorf University Hospital, Moorenstr. 5, 40225 Duesseldorf (Germany)], E-mail: blondin@med.uni-duesseldorf.de

    2009-02-15

    Objective: The aim was to compare the diagnostic performance and handling of dynamic contrast-enhanced MRI of the breast with two commercial software solutions ('CADstream' and '3TP') and one self-developed software system ('Mammatool'). Materials and methods: Identical data sets of dynamic breast MRI from 21 patients were evaluated retrospectively with all three software systems. The exams were classified according to the BI-RADS classification. The number of lesions in the parametric mapping was compared to histology or follow-up of more than 2 years. In addition, 25 quality criteria were judged by 3 independent investigators with a score from 0 to 5. Statistical analysis was performed to document the quality ranking of the different software systems. Results: There were 9 invasive carcinomas, one pure DCIS, one papilloma, one radial scar, three histologically proven changes due to mastopathy, one adenosis and two fibroadenomas. Additionally two patients with enhancing parenchyma followed with MRI for more than 3 years and one scar after breast conserving therapy were included. All malignant lesions were classified as BI-RADS 4 or 5 using all software systems and showed significant enhancement in the parametric mapping. 'CADstream' showed the best score on subjective quality criteria. '3TP' showed the lowest number of false-positive results. 'Mammatool' produced the lowest number of benign tissues indicated with parametric overlay. Conclusion: All three software programs tested were adequate for sensitive and efficient assessment of dynamic MRI of the breast. Improvements in specificity may be achievable.

  15. The accuracy of magnetic resonance imaging and ultrasound in evaluating the size of early-stage breast neoplasms

    Institute of Scientific and Technical Information of China (English)

    Zheng Wang; Hongzhi Chen; Xiaobin Ma; Zhijun Dai; Shuai Lin; Huafeng Kang

    2016-01-01

    Objective Breast cancer is the most frequently diagnosed cancer in women. Accurate evaluation of the size and extent of the tumor is crucial in selecting a suitable surgical method for patients with breast cancer. Both overestimation and underestimation have important adverse ef ects on patient care. This study aimed to evaluate the accuracy of breast magnetic resonance imaging (MRI) and ultrasound (US) examination for measuring the size and extent of early-stage breast neoplasms. Methods The longest diameter of breast tumors in patients with T1–2N0–1M0 invasive breast cancer prepar-ing for breast-conserving surgery (BCS) was measured preoperatively by using both MRI and US and their accuracy was compared with that of postoperative pathologic examination. If the diameter dif erence was within 2 mm, it was considered to be consistent with pathologic examination. Results A total of 36 patients were imaged using both MRI and US. The mean longest diameter of the tu-mors on MRI, US, and postoperative pathologic examination was 20.86 mm ± 4.09 mm (range: 11–27 mm), 16.14 mm ± 4.91 mm (range: 6–26 mm), and 18.36 mm ± 3.88 mm (range: 9–24 mm). US examination underestimated the size of the tumor compared to that determined using pathologic examination (t = 3.49, P 0.05). Conclusion MRI and US are both ef ective methods to assess the size of breast tumors, and they main-tain good consistency with pathologic examination. MRI has a better correlation with pathology. However, we should be careful about the risk of inaccurate size estimation.

  16. Dynamic characteristics of multi-walled carbon nanotubes under a transverse magnetic field

    Indian Academy of Sciences (India)

    S Li; H J Xie; X Wang

    2011-02-01

    This paper reports the results of an investigation into the effect of transverse magnetic fields on dynamic characteristics of multi-walled carbon nanotubes (MWNTs). Couple dynamic equations of MWNTs subjected to a transverse magnetic field are derived and solved by considering the Lorentz magnetic forces induced by a transverse magnetic field exerted on MWCNTs. Results show that the transverse magnetic field exerted on MWNTs makes the lowest frequency of the MWNTs nonlinearly decrease and the highest frequency, changeless. When the strength of applied transverse magnetic fields is larger than a given value the two walls of MWNTs appear in the radial and axial coaxial vibration phenomena.

  17. Nonlinear dynamic behaviors of permanent magnet synchronous motors in electric vehicles caused by unbalanced magnetic pull

    Science.gov (United States)

    Xiang, Changle; Liu, Feng; Liu, Hui; Han, Lijin; Zhang, Xun

    2016-06-01

    Unbalanced magnetic pull (UMP) plays a key role in nonlinear dynamic behaviors of permanent magnet synchronous motors (PMSM) in electric vehicles. Based on Jeffcott rotor model, the stiffness characteristics of the rotor system of the PMSM are analyzed and the nonlinear dynamic behaviors influenced by UMP are investigated. In free vibration study, eigenvalue-based stability analysis for multiple equilibrium points is performed which offers an insight in system stiffness. Amplitude modulation effects are discovered of which the mechanism is explained and the period of modulating signal is carried out by phase analysis and averaging method. The analysis indicates that the effects are caused by the interaction of the initial phases of forward and backward whirling motions. In forced vibration study, considering dynamic eccentricity, frequency characteristics revealing softening type are obtained by harmonic balance method, and the stability of periodic solution is investigated by Routh-Hurwitz criterion. The frequency characteristics analysis indicates that the response amplitude is limited in the range between the amplitudes of the two kinds of equilibrium points. In the vicinity of the continuum of equilibrium points, the system hardly provides resistance to bending, and hence external disturbances easily cause loss of stability. It is useful for the design of the PMSM with high stability and low vibration and acoustic noise.

  18. Quantum-mechanical relaxation model for characterization of fine particles magnetic dynamics in an external magnetic field

    Science.gov (United States)

    Mischenko, I.; Chuev, M.

    2016-12-01

    Principal difference of magnetic nanoparticles from the bulk matter which cannot be ignored when constructing upon them combined metamaterials and modern devices is the essential influence on their behavior thermal fluctuations of the environment. These disturbances lead to specific distributions of the particles characteristics and to stochastic reorientations of their magnetic moments. On the basis of quantum-mechanical representation of the particle possessing intrinsic magnetic anisotropy and being placed onto the external magnetic field we developed general approach to describe equilibrium magnetization curves and relaxation Mössbauer spectra of magnetic nanoparticles for diagnostics of magnetic nanomaterials in the whole temperature or external field ranges. This approach has universal character and may be applied not only to the systems under thermal equilibrium, but may in principle describe macroscopic dynamical phenomena such as magnetization reversal.

  19. Dynamics of Exploding Plasma Within a Magnetized Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Dimonte, G; Dipeso, G; Hewett, D

    2002-02-01

    This memo describes several possible laboratory experiments on the dynamics of an exploding plasma in a background magnetized plasma. These are interesting scientifically and the results are applicable to energetic explosions in the earth's ionosphere (DOE Campaign 7 at LLNL). These proposed experiments are difficult and can only be performed in the new LAPD device at UCLA. The purpose of these experiments would be to test numerical simulations, theory and reduced models for systems performance codes. The experiments are designed to investigate the affect of the background plasma on (1) the maximum diamagnetic bubble radius given by Eq. 9; and (2) the Alfven wave radiation efficiency produced by the induced current J{sub A} (Eqs. 10-12) These experiments involve measuring the bubble radius using a fast gated optical imager as in Ref [1] and the Alfven wave profile and intensity as in Ref [2] for different values of the exploding plasma energy, background plasma density and temperature, and background magnetic field. These experiments extend the previously successful experiments [2] on Alfven wave coupling. We anticipate that the proposed experiments would require 1-2 weeks of time on the LAPD. We would perform PIC simulations in support of these experiments in order to validate the codes. Once validated, the PIC simulations would then be able to be extended to realistic ionospheric conditions with various size explosions and altitudes. In addition to the Alfven wave coupling, we are interested in the magnetic containment and transport of the exploding ''debris'' plasma to see if the shorting of the radial electric field in the magnetic bubble would allow the ions to propagate further. This has important implications in an ionospheric explosion because it defines the satellite damage region. In these experiments, we would field fast gated optical cameras to obtain images of the plasma expansion, which could then be correlated with magnetic

  20. Magnetic soft x-ray microscopy-imaging fast spin dynamics inmagnetic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Peter; Kim, Dong-Hyun; Mesler, Brooke L.; Chao, Weilun; Sakdinawat, Anne E.; Anderson, Erik H.

    2007-06-01

    Magnetic soft X-ray microscopy combines 15nm spatial resolution with 70ps time resolution and elemental sensitivity. Fresnel zone plates are used as X-ray optics and X-ray magnetic circular dichroism serves as magnetic contrast mechanism. Thus scientifically interesting and technologically relevant low dimensional nanomagnetic systems can be imaged at fundamental length and ultrafast time scales in a unique way. Studies include magnetization reversal in magnetic multilayers, nanopatterned systems, vortex dynamics in nanoelements and spin current induced phenomena.

  1. Hybrid magnetic – Semiconductor nanocomposites: optical, magnetic and nanosecond dynamical properties

    Energy Technology Data Exchange (ETDEWEB)

    Emam, A.N.; Girgis, E.; Mostafa, A.A. [National Research Center, Dokki, Giza (Egypt); Guirguis, O.W. [Biophysics Department, Faculty of Science, Cairo University, Giza (Egypt); Mohamed, M.B., E-mail: monabmohamed@gmail.com [National Institute of Laser Enhanced Science, Cairo University, Giza (Egypt); NanoTech Egypt for Photoelectronics, Dreamland, Giza (Egypt)

    2015-07-15

    A series of colloidal CdSe quantum dots doped with different concentration of cobalt ions has been prepared via organometallic pyrolysis of a mixture of cadmium stearate and cobalt dithiocarbazate. The conditions required for successful doping depend on the source of cobalt ions and the dopant concentration. The structure and morphology of the prepared nanocrystals have been characterized using X-Ray Diffraction (XRD), and Transmission Electron Microscope (TEM). Slight shift in the interplaner space was observed in the XRD pattern of the doped nanocrystals. Formation of separate cobalt nanoclusters has been observed in the TEM images upon increasing the cobalt concentration more than 2% of the original cadmium concentration. This was confirmed by magnetic measurements of the prepared samples. Room-temperature ferromagnetism has been observed, in which the switching field increases as the cobalt ratio increases. Increasing the cobalt ratio more than 5% increases the coercivity due to formation of Co{sup 0} nanoclusters. Moreover, the presence of localized magnetic ions in semiconductor QDs leads to strong exchange interactions between sp band electrons and the magnetic ions d electrons. This would influence the optical properties such as absorption, emission, as well as nanosecond relaxation dynamics. - Graphical abstract: Display Omitted - Highlights: • Hybrid semiconductor-magnetic nanostructure was prepared via chemical method. • Room-temperature ferromagnetism for hybrid CdSe–Co quantum dots has been observed. • Co{sup +2} ions induces slight shift in the interplaner space distance of the doped QDs. • Hybrid CdSe–Co QDs have better quantum yield than pure CdSe QDs. • Hybrid CdSe–Co nanocrystals have faster electron-hole dynamics than pure CdSe QDs.

  2. Lactation in the Human Breast From a Fluid Dynamics Point of View.

    Science.gov (United States)

    Negin Mortazavi, S; Geddes, Donna; Hassanipour, Fatemeh

    2017-01-01

    This study is a collaborative effort among lactation specialists and fluid dynamic engineers. The paper presents clinical results for suckling pressure pattern in lactating human breast as well as a 3D computational fluid dynamics (CFD) modeling of milk flow using these clinical inputs. The investigation starts with a careful, statistically representative measurement of suckling vacuum pressure, milk flow rate, and milk intake in a group of infants. The results from clinical data show that suckling action does not occur with constant suckling rate but changes in a rhythmic manner for infants. These pressure profiles are then used as the boundary condition for the CFD study using commercial ansys fluent software. For the geometric model of the ductal system of the human breast, this work takes advantage of a recent advance in the development of a validated phantom that has been produced as a ground truth for the imaging applications for the breast. The geometric model is introduced into CFD simulations with the aforementioned boundary conditions. The results for milk intake from the CFD simulation and clinical data were compared and cross validated. Also, the variation of milk intake versus suckling pressure are presented and analyzed. Both the clinical and CFD simulation show that the maximum milk flow rate is not related to the largest vacuum pressure or longest feeding duration indicating other factors influence the milk intake by infants.

  3. Quantitative evaluation of small breast masses using a compartment model analysis on dynamic MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Osamu; Morishita, Shoji; Kido, Taeko; Kitajima, Mika; Okamura, Kenji; Fukuda, Seiji [Kumamoto Rosai Hospital, Yatsushiro (Japan); Yamashita, Yasuyuki; Takahashi, Mutsumasa

    1998-07-01

    To differentiate between malignant and benign breast masses using a compartmental analysis, 55 patients with breast masses (fibroadenoma, n=22; invasive ductal carcinoma, n=29; noninvasive ductal carcinoma, n=8) underwent Gd-DTPA enhanced dynamic MR imaging. Dynamic MR images obtained using two-dimensional fat-saturated fast multiplanar corrupted gradient echo technique over 10 minutes following bolus injection of Gd-DTPA. The triexponential concentration curve of Gd-DTPA was fitted to a theoretical model based on compartmental analysis. Using this method, the transfer constant (or permeability surface product per unit volume of component k) and f{sub 3}/f{sub 1}=f were measured, where f{sub 1} represents tumor vessel volume and f{sub 3} represents extracellular volume. The k value was significantly greater (p<0.01) for malignant tumors, and the k value seen in cases of noninvasive ductal carcinoma was less than that for invasive ductal carcinoma. The f value was significantly smaller (p<0.01) for malignant tumors, whereas the f value for noninvasive ductal carcinoma was not significantly different from that for invasive ductal carcinoma. We believe that this type of compartmental analysis may be of value for the evaluation of breast masses. (author)

  4. Using NV centers to probe magnetization dynamics in normal metal/magnetic insulator hybrid system at the nanoscale

    Science.gov (United States)

    Zhang, Huiliang; Ku, Mark J. H.; Han, Minyong; Casola, Francesco; van der Sar, Toeno; Yacoby, Amir; Walsworth, Ronald L.

    2016-05-01

    Understanding magnetization dynamics induced by electric current is of great interest for both fundamental and practical reasons. Great endeavor has been dedicated to spin-orbit torques (SOT) in metallic structures, while quantitative study of analogous phenomena in magnetic insulators remains challenging where transport measurements are not feasible. Recently we have developed techniques using nitrogen vacancy (NV) centers in diamond to probe few-nanometre-scale correlated-electron magnetic excitations (i.e., spin waves). Here we demonstrate how this powerful tool can be implemented to study magnetization dynamics inside ferromagnetic insulator, Yttrium iron garnet (YIG) with spin injection from electrical current through normal metal (Platinum in our case). Particularly our work will focus on NV magnetic detection, imaging, and spectroscopy of coherent auto-oscillations in Pt/YIG microdisc. Magnetic fluctuations and local temperature measurements, both with nearby NV centers, will also be interesting topics relevant to SOT physics in Pt/YIG hybrid system.

  5. Synthesis of polydopamine as a new and biocompatible coating of magnetic nanoparticles for delivery of doxorubicin in mouse breast adenocarcinoma.

    Science.gov (United States)

    Zavareh, Saeed; Mahdi, Milad; Erfanian, Soheyla; Hashemi-Moghaddam, Hamid

    2016-11-01

    Carrier-mediated drug delivery systems can be used to increase the intracellular concentration of drugs in cancerous cells, thereby improving drug biodistribution and minimizing unwanted side effects. This study aimed to investigate the effect of synthesized magnetic molecularly imprinted polydopamine for controlled doxorubicin (DOX) delivery in a breast adenocarcinoma model of BALB/c mice with an external magnetic field. The synthesized DOX-imprinted polydopamine (DOX-IP) was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The efficacy of DOX-IP in tumor growth suppression was assessed in terms of tumor growth delay, tumor doubling time, inhibition ratio, and histopathology. High-performance liquid chromatography and flame atomic absorption spectrometry were performed to investigate the drug distribution among tissues. The findings showed higher efficacy of DOX-IP with magnetic field in suppressing tumor growth than free DOX and DOX-IP without magnetic field. Significantly high DOX concentration in tumor tissue was found in the DOX-IP group with magnetic field. Magnetic DOX-IP demonstrates effective tumor-targeted drug delivery in a mouse model of breast cancer.

  6. Membrane proteins structure and dynamics by nuclear magnetic resonance.

    Science.gov (United States)

    Maltsev, Sergey; Lorigan, Gary A

    2011-10-01

    Membrane proteins represent a challenging class of biological systems to study. They are extremely difficult to crystallize and in most cases they retain their structure and functions only in membrane environments. Therefore, commonly used diffraction methods fail to give detailed molecular structure and other approaches have to be utilized to obtain biologically relevant information. Nuclear magnetic resonance (NMR) spectroscopy, however, can provide powerful structural and dynamical constraints on these complicated systems. Solution- and solid-state NMR are powerful methods for investigating membrane proteins studies. In this work, we briefly review both solution and solid-state NMR techniques for membrane protein studies and illustrate the applications of these methods to elucidate proteins structure, conformation, topology, dynamics, and function. Recent advances in electronics, biological sample preparation, and spectral processing provided opportunities for complex biological systems, such as membrane proteins inside lipid vesicles, to be studied faster and with outstanding quality. New analysis methods therefore have emerged, that benefit from the combination of sample preparation and corresponding specific high-end NMR techniques, which give access to more structural and dynamic information.

  7. Semi-LASER localized dynamic 31P magnetic resonance spectroscopy in exercising muscle at ultra-high magnetic field.

    NARCIS (Netherlands)

    Meyerspeer, M.; Scheenen, T.W.J.; Schmid, A.I.; Mandl, T.; Unger, E.; Moser, E.

    2011-01-01

    Magnetic resonance spectroscopy (MRS) can benefit from increased signal-to-noise ratio (SNR) of high magnetic fields. In this work, the SNR gain of dynamic 31P MRS at 7 T was invested in temporal and spatial resolution. Using conventional slice selective excitation combined with localization by adia

  8. Spin Dynamics simulations of the dynamic properties of classical models for magnetic materials

    Science.gov (United States)

    Bunker, Alex; Landau, D. P.

    1998-03-01

    The Spin Dynamics simulation technique, which has had considerable success for the study of critical properties of classical Heisenberg antiferromagnets(A. Bunker, K. Chen, and D. P. Landau Phys. Rev. B) \\underline54, 9259 (1996), has been used to determine more general properties for a wider range of materials. A general spin dynamics program has been developed which can determine the dynamic structure factor, S(q,ω), in the [100], [110], and [111] directions for a wide range of classical magnetic models at any temperature desired. We have simulated the magnetic dynamics in the ordered phase of the isotropic Heisenberg model with both ferromagnetic and antiferromagnetic coupling on L×L×L BCC and SC lattices. Outside of the critical regime relatively small lattice sizes of L = 12, 24 could be used. From our simulation we have determined the stiffness coefficient and the spin relaxation rate which were compared to both experimental(J. Als-Nielsen in Phase Transitions and Critical Phenomena), ed. C. Domb, M. S. Green, Academic Press, (1976) and theoretical results. We have performed the same simulation with anisotropy appropriate for MnF2 and FeF_2. Research supported in part by the NSF

  9. Examining the pathogenesis of breast cancer using a novel agent-based model of mammary ductal epithelium dynamics.

    Directory of Open Access Journals (Sweden)

    Joaquin Chapa

    Full Text Available The study of the pathogenesis of breast cancer is challenged by the long time-course of the disease process and the multi-factorial nature of generating oncogenic insults. The characterization of the longitudinal pathogenesis of malignant transformation from baseline normal breast duct epithelial dynamics may provide vital insight into the cascading systems failure that leads to breast cancer. To this end, extensive information on the baseline behavior of normal mammary epithelium and breast cancer oncogenesis was integrated into a computational model termed the Ductal Epithelium Agent-Based Model (DEABM. The DEABM is composed of computational agents that behave according to rules established from published cellular and molecular mechanisms concerning breast duct epithelial dynamics and oncogenesis. The DEABM implements DNA damage and repair, cell division, genetic inheritance and simulates the local tissue environment with hormone excretion and receptor signaling. Unrepaired DNA damage impacts the integrity of the genome within individual cells, including a set of eight representative oncogenes and tumor suppressors previously implicated in breast cancer, with subsequent consequences on successive generations of cells. The DEABM reproduced cellular population dynamics seen during the menstrual cycle and pregnancy, and demonstrated the oncogenic effect of known genetic factors associated with breast cancer, namely TP53 and Myc, in simulations spanning ∼40 years of simulated time. Simulations comparing normal to BRCA1-mutant breast tissue demonstrated rates of invasive cancer development similar to published epidemiologic data with respect to both cumulative incidence over time and estrogen-receptor status. Investigation of the modeling of ERα-positive (ER+ tumorigenesis led to a novel hypothesis implicating the transcription factor and tumor suppressor RUNX3. These data suggest that the DEABM can serve as a potentially valuable framework to

  10. Examining the pathogenesis of breast cancer using a novel agent-based model of mammary ductal epithelium dynamics.

    Science.gov (United States)

    Chapa, Joaquin; Bourgo, Ryan J; Greene, Geoffrey L; Kulkarni, Swati; An, Gary

    2013-01-01

    The study of the pathogenesis of breast cancer is challenged by the long time-course of the disease process and the multi-factorial nature of generating oncogenic insults. The characterization of the longitudinal pathogenesis of malignant transformation from baseline normal breast duct epithelial dynamics may provide vital insight into the cascading systems failure that leads to breast cancer. To this end, extensive information on the baseline behavior of normal mammary epithelium and breast cancer oncogenesis was integrated into a computational model termed the Ductal Epithelium Agent-Based Model (DEABM). The DEABM is composed of computational agents that behave according to rules established from published cellular and molecular mechanisms concerning breast duct epithelial dynamics and oncogenesis. The DEABM implements DNA damage and repair, cell division, genetic inheritance and simulates the local tissue environment with hormone excretion and receptor signaling. Unrepaired DNA damage impacts the integrity of the genome within individual cells, including a set of eight representative oncogenes and tumor suppressors previously implicated in breast cancer, with subsequent consequences on successive generations of cells. The DEABM reproduced cellular population dynamics seen during the menstrual cycle and pregnancy, and demonstrated the oncogenic effect of known genetic factors associated with breast cancer, namely TP53 and Myc, in simulations spanning ∼40 years of simulated time. Simulations comparing normal to BRCA1-mutant breast tissue demonstrated rates of invasive cancer development similar to published epidemiologic data with respect to both cumulative incidence over time and estrogen-receptor status. Investigation of the modeling of ERα-positive (ER+) tumorigenesis led to a novel hypothesis implicating the transcription factor and tumor suppressor RUNX3. These data suggest that the DEABM can serve as a potentially valuable framework to augment the

  11. Recurrence and mortality according to Estrogen Receptor status for breast cancer patients undergoing conservative surgery. Ipsilateral breast tumour recurrence dynamics provides clues for tumour biology within the residual breast

    Directory of Open Access Journals (Sweden)

    Ferraris Cristina

    2010-11-01

    Full Text Available Abstract Background the study was designed to determine how tumour hormone receptor status affects the subsequent pattern over time (dynamics of breast cancer recurrence and death following conservative primary breast cancer resection. Methods Time span from primary resection until both first recurrence and death were considered among 2825 patients undergoing conservative surgery with or without breast radiotherapy. The hazard rates for ipsilateral breast tumour recurrence (IBTR, distant metastasis (DM and mortality throughout 10 years of follow-up were assessed. Results DM dynamics displays the same bimodal pattern (first early peak at about 24 months, second late peak at the sixth-seventh year for both estrogen receptor (ER positive (P and negative (N tumours and for all local treatments and metastatic sites. The hazard rates for IBTR maintain the bimodal pattern for ERP and ERN tumours; however, each IBTR recurrence peak for ERP tumours is delayed in comparison to the corresponding timing of recurrence peaks for ERN tumours. Mortality dynamics is markedly different for ERP and ERN tumours with more early deaths among patients with ERN than among patients with ERP primary tumours. Conclusion DM dynamics is not influenced by the extent of conservative primary tumour resection and is similar for both ER phenotypes across different metastatic sites, suggesting similar mechanisms for tumour development at distant sites despite apparently different microenvironments. The IBTR risk peak delay observed in ERP tumours is an exception to the common recurrence risk rhythm. This suggests that the microenvironment within the residual breast tissue may enforce more stringent constraints upon ERP breast tumour cell growth than other tissues, prolonging the latency of IBTR. This local environment is, however, apparently less constraining to ERN cells, as IBTR dynamics is similar to the corresponding recurrence dynamics among other distant tissues.

  12. Analysis and Optimisation of Pulse Dynamics for Magnetic Stimulation

    CERN Document Server

    Goetz, Stefan M; Gerhofer, Manuel G; Weyh, Thomas; Herzog, Hans-Georg

    2011-01-01

    Magnetic stimulation is a standard tool in brain research and many fields of neurology, as well as psychiatry. From a physical perspective, one key aspect of this method is the inefficiency of available setups. Whereas the spatial field properties have been studied rather intensively with coil designs, the dynamics have been neglected almost completely for a long time. Instead, the devices and their technology defined the waveform. Here, an analysis of the waveform space is performed. Based on these data, an appropriate optimisation approach is outlined which makes use of a modern nonlinear axon description of a mammalian motor nerve. The approach is based on a hybrid global-local method; different coordinate systems for describing the continuous waveforms in a limited parameter space are defined for sufficient stability. The results of the numeric setup suggest that there is plenty of room for waveforms with higher efficiency than the traditional shapes. One class of such pulses is analysed further. Although...

  13. DYNAMIC COMPACTION OF PURE COPPER POWDER USING PULSED MAGNETIC FORCE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The compaction of pure Cu powder was carried out through a series of experiments using dynamic magnetic pulse compaction, and the effects of process parameters, such as discharge energy and compacting direction, on the homogeneity and the compaction density of compacted specimens were presented and discussed. The results indicated that the compaction density of specimens increased with the augment of discharge voltage and time. During unidirectional compaction, there was a density gradient along the loading direction in the compacted specimen, and the minimum compaction density was localized to the center of the bottom of the specimen. The larger the aspect ratio of a powder body, the higher the compaction density of the compacted specimen. And high conductivity drivers were beneficial to the increase of the compaction density. The iterative and the double direction compaction were efficient means to manufacture the homogeneous and high-density powder parts.

  14. Dynamic RKKY interaction between magnetic moments in graphene nanoribbons

    Science.gov (United States)

    Guimarães, F. S. M.; Duffy, J.; Costa, A. T.; Muniz, R. B.; Ferreira, M. S.

    2016-12-01

    Graphene has been identified as a promising material with numerous applications, particularly in spintronics. In this paper we investigate the peculiar features of spin excitations of magnetic units deposited on graphene nanoribbons and how they can couple through a dynamical interaction mediated by spin currents. We examine in detail the spin lifetimes and identify a pattern caused by vanishing density of states sites in pristine ribbons with armchair borders. Impurities located on these sites become practically invisible to the interaction but can be made accessible by a gate voltage or doping. We also demonstrate that the coupling between impurities can be turned on or off using this characteristic, which may be used to control the transfer of information in transistorlike devices.

  15. The Added Diagnostic Value of Dynamic Contrast-Enhanced MRI at 3.0 T in Nonpalpable Breast Lesions

    Science.gov (United States)

    Merckel, Laura G.; Verkooijen, Helena M.; Peters, Nicky H. G. M.; Mann, Ritse M.; Veldhuis, Wouter B.; Storm, Remmert K.; Weits, Teun; Duvivier, Katya M.; van Dalen, Thijs; Mali, Willem P. Th. M.; Peeters, Petra H. M.; van den Bosch, Maurice A. A. J.

    2014-01-01

    Objective To investigate the added diagnostic value of 3.0 Tesla breast MRI over conventional breast imaging in the diagnosis of in situ and invasive breast cancer and to explore the role of routine versus expert reading. Materials and Methods We evaluated MRI scans of patients with nonpalpable BI-RADS 3–5 lesions who underwent dynamic contrast-enhanced 3.0 Tesla breast MRI. Initially, MRI scans were read by radiologists in a routine clinical setting. All histologically confirmed index lesions were re-evaluated by two dedicated breast radiologists. Sensitivity and specificity for the three MRI readings were determined, and the diagnostic value of breast MRI in addition to conventional imaging was assessed. Interobserver reliability between the three readings was evaluated. Results MRI examinations of 207 patients were analyzed. Seventy-eight of 207 (37.7%) patients had a malignant lesion, of which 33 (42.3%) patients had pure DCIS and 45 (57.7%) invasive breast cancer. Sensitivity of breast MRI was 66.7% during routine, and 89.3% and 94.7% during expert reading. Specificity was 77.5% in the routine setting, and 61.0% and 33.3% during expert reading. In the routine setting, MRI provided additional diagnostic information over clinical information and conventional imaging, as the Area Under the ROC Curve increased from 0.76 to 0.81. Expert MRI reading was associated with a stronger improvement of the AUC to 0.87. Interobserver reliability between the three MRI readings was fair and moderate. Conclusions 3.0 T breast MRI of nonpalpable breast lesions is of added diagnostic value for the diagnosis of in situ and invasive breast cancer. PMID:24713637

  16. The added diagnostic value of dynamic contrast-enhanced MRI at 3.0 T in nonpalpable breast lesions.

    Directory of Open Access Journals (Sweden)

    Laura G Merckel

    Full Text Available OBJECTIVE: To investigate the added diagnostic value of 3.0 Tesla breast MRI over conventional breast imaging in the diagnosis of in situ and invasive breast cancer and to explore the role of routine versus expert reading. MATERIALS AND METHODS: We evaluated MRI scans of patients with nonpalpable BI-RADS 3-5 lesions who underwent dynamic contrast-enhanced 3.0 Tesla breast MRI. Initially, MRI scans were read by radiologists in a routine clinical setting. All histologically confirmed index lesions were re-evaluated by two dedicated breast radiologists. Sensitivity and specificity for the three MRI readings were determined, and the diagnostic value of breast MRI in addition to conventional imaging was assessed. Interobserver reliability between the three readings was evaluated. RESULTS: MRI examinations of 207 patients were analyzed. Seventy-eight of 207 (37.7% patients had a malignant lesion, of which 33 (42.3% patients had pure DCIS and 45 (57.7% invasive breast cancer. Sensitivity of breast MRI was 66.7% during routine, and 89.3% and 94.7% during expert reading. Specificity was 77.5% in the routine setting, and 61.0% and 33.3% during expert reading. In the routine setting, MRI provided additional diagnostic information over clinical information and conventional imaging, as the Area Under the ROC Curve increased from 0.76 to 0.81. Expert MRI reading was associated with a stronger improvement of the AUC to 0.87. Interobserver reliability between the three MRI readings was fair and moderate. CONCLUSIONS: 3.0 T breast MRI of nonpalpable breast lesions is of added diagnostic value for the diagnosis of in situ and invasive breast cancer.

  17. SPILADY: A parallel CPU and GPU code for spin-lattice magnetic molecular dynamics simulations

    Science.gov (United States)

    Ma, Pui-Wai; Dudarev, S. L.; Woo, C. H.

    2016-10-01

    Spin-lattice dynamics generalizes molecular dynamics to magnetic materials, where dynamic variables describing an evolving atomic system include not only coordinates and velocities of atoms but also directions and magnitudes of atomic magnetic moments (spins). Spin-lattice dynamics simulates the collective time evolution of spins and atoms, taking into account the effect of non-collinear magnetism on interatomic forces. Applications of the method include atomistic models for defects, dislocations and surfaces in magnetic materials, thermally activated diffusion of defects, magnetic phase transitions, and various magnetic and lattice relaxation phenomena. Spin-lattice dynamics retains all the capabilities of molecular dynamics, adding to them the treatment of non-collinear magnetic degrees of freedom. The spin-lattice dynamics time integration algorithm uses symplectic Suzuki-Trotter decomposition of atomic coordinate, velocity and spin evolution operators, and delivers highly accurate numerical solutions of dynamic evolution equations over extended intervals of time. The code is parallelized in coordinate and spin spaces, and is written in OpenMP C/C++ for CPU and in CUDA C/C++ for Nvidia GPU implementations. Temperatures of atoms and spins are controlled by Langevin thermostats. Conduction electrons are treated by coupling the discrete spin-lattice dynamics equations for atoms and spins to the heat transfer equation for the electrons. Worked examples include simulations of thermalization of ferromagnetic bcc iron, the dynamics of laser pulse demagnetization, and collision cascades.

  18. Similarity of Fibroglandular Breast Tissue Content Measured from Magnetic Resonance and Mammographic Images and by a Mathematical Algorithm

    Directory of Open Access Journals (Sweden)

    Fatima Nayeem

    2014-01-01

    Full Text Available Women with high breast density (BD have a 4- to 6-fold greater risk for breast cancer than women with low BD. We found that BD can be easily computed from a mathematical algorithm using routine mammographic imaging data or by a curve-fitting algorithm using fat and nonfat suppression magnetic resonance imaging (MRI data. These BD measures in a strictly defined group of premenopausal women providing both mammographic and breast MRI images were predicted as well by the same set of strong predictor variables as were measures from a published laborious histogram segmentation method and a full field digital mammographic unit in multivariate regression models. We also found that the number of completed pregnancies, C-reactive protein, aspartate aminotransferase, and progesterone were more strongly associated with amounts of glandular tissue than adipose tissue, while fat body mass, alanine aminotransferase, and insulin like growth factor-II appear to be more associated with the amount of breast adipose tissue. Our results show that methods of breast imaging and modalities for estimating the amount of glandular tissue have no effects on the strength of these predictors of BD. Thus, the more convenient mathematical algorithm and the safer MRI protocols may facilitate prospective measurements of BD.

  19. An 11-channel radio frequency phased array coil for magnetic resonance guided high-intensity focused ultrasound of the breast.

    Science.gov (United States)

    Minalga, E; Payne, A; Merrill, R; Todd, N; Vijayakumar, S; Kholmovski, E; Parker, D L; Hadley, J R

    2013-01-01

    In this study, a radio frequency phased array coil was built to image the breast in conjunction with a magnetic resonance guided high-intensity focused ultrasound (MRgHIFU) device designed specifically to treat the breast in a treatment cylinder with reduced water volume. The MRgHIFU breast coil was comprised of a 10-channel phased array coil placed around an MRgHIFU treatment cylinder where nearest-neighbor decoupling was achieved with capacitive decoupling in a shared leg. In addition a single loop coil was placed at the chest wall making a total of 11 channels. The radio frequency coil array design presented in this work was chosen based on ease of implementation, increased visualization into the treatment cylinder, image reconstruction speed, temporal resolution, and resulting signal-to-noise ratio profiles. This work presents a dedicated 11-channel coil for imaging of the breast tissue in the MRgHIFU setup without obstruction of the ultrasound beam and, specifically, compares its performance in signal-to-noise, overall imaging time, and temperature measurement accuracy to that of the standard single chest-loop coil typically used in breast MRgHIFU. Copyright © 2012 Wiley Periodicals, Inc.

  20. Improvement of dose distribution in breast radiotherapy using a reversible transverse magnetic field Linac-MR unit

    Energy Technology Data Exchange (ETDEWEB)

    Esmaeeli, A. D., E-mail: ali-esmaeeli-d@yahoo.com [Department of Physics, Rasht Branch, Islamic Azad University, Rasht, 41476-54919 (Iran, Islamic Republic of); Mahdavi, S. R. [Department of Medical Physics, Tehran University of Medical Sciences, Tehran, 14174 (Iran, Islamic Republic of); Pouladian, M.; Bagheri, S. [Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, 14778-93855 (Iran, Islamic Republic of); Monfared, A. S. [Department of Medical Physics, Babol University of Medical Sciences, Babol, 47148-71167 (Iran, Islamic Republic of)

    2014-01-15

    Purpose: To investigate the improvement in dose distribution in tangential breast radiotherapy using a reversible transverse magnetic field that maintains the same direction of Lorentz force between two fields. The investigation has a potential application in future Linac-MR units. Methods: Computed tomography images of four patients and magnetic fields of 0.25–1.5 Tesla (T) were used for Monte Carlo simulation. Two patients had intact breast while the other two had mastectomy. Simulations of planning and chest wall irradiation were similar to the actual clinical process. The direction of superior-inferior magnetic field for the medial treatment beam was reversed for the lateral beam. Results: For the ipsilateral lung and heart mean doses were reduced by a mean (range) of 45.8% (27.6%–58.6%) and 26.0% (20.2%–38.9%), respectively, depending on various treatment plan setups. The mean V{sub 20} for ipsilateral lung was reduced by 55.0% (43.6%–77.3%). In addition acceptable results were shown after simulation of 0.25 T magnetic field demonstrated in dose-volume reductions of the heart, ipsilateral lung, and noninvolved skin. Conclusions: Applying a reversible magnetic field during breast radiotherapy, not only reduces the dose to the lung and heart but also produces a sharp drop dose volume histogram for planning target volume, because of bending of the path of secondary charged particles toward the chest wall by the Lorentz force. The simulations have shown that use of the magnetic field at 1.5 T is not feasible for clinical applications due to the increase of ipsilateral chest wall skin dose in comparison to the conventional planning while 0.25 T is suitable for all patients due to dose reduction to the chest wall skin.

  1. Dynamic magnetic susceptibility of systems with long-range magnetic order

    Energy Technology Data Exchange (ETDEWEB)

    Vannette, Matthew Dano [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, χ, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies (~10-30 MHz). In the vicinity of TC local moment ferromagnets show a very sharp, narrow peak in χ which is suppressed in amplitude and shifted to higher temperatures as the static bias field is increased. Unexpectedly, critical scaling analysis fails for these data. It is seen that these data are frequency dependent, however there is no simple method whereby measurement frequency can be changed in a controllable fashion. In contrast, itinerant ferromagnets show a broad maximum in χ well below TC which is suppressed and shifts to lower temperatures as the dc bias field is increased. The data on itinerant ferromagnets is fitted to a semi-phenomenological model that suggests the sample response is dominated by the uncompensated minority spins in the conduction band. Concluding remarks suggest possible scenarios to achieve frequency resolved data using the TDR as well as other fields in which the apparatus may be exploited.

  2. Magnetic thermotherapy of breast tumors: an experimental therapeutic approach; Magnetische Thermotherapie von Tumoren der Brust: ein experimenteller Therapieansatz

    Energy Technology Data Exchange (ETDEWEB)

    Hilger, I.; Kaiser, W.A. [Inst. fuer Diagnostische und Interventionelle Radiologie des Klinikums der Friedrich-Schiller-Univ. Jena (Germany); Andrae, W.; Hergt, R.; Hiergeist, R. [Inst. fuer Physikalische Hochtechnologie e.V., Jena (Germany)

    2005-04-01

    The therapeutic strategy for breast cancer is changing, especially for early tumor stages with good prognosis. One potential minimally invasive therapy modality consists in the accumulation of a well-tolerated magnetic material (iron oxides, particularly magnetite) in the target tissue. By applying an alternating magnetic field, energy is selectively absorbed and induces harmful heating of the tumor. The present review deals with the essential conditions and parameters as studied in vitro and in vivo in animal experiments. Extrapolations to the clinical situation are discussed, in particular, the heating potential of the magnetic material, the selection of the magnetic field parameters, the occurrence of eddy currents, the generation of localized heating spots and the expected temperature rises and their effects on the tumor area. (orig.)

  3. Preliminary analysis of the MER magnetic properties experiment using a computational fluid dynamics model

    DEFF Research Database (Denmark)

    Kinch, K.M.; Merrison, J.P.; Gunnlaugsson, H.P.;

    2006-01-01

    Motivated by questions raised by the magnetic properties experiments on the NASA Mars Pathfinder and Mars Exploration Rover (MER) missions, we have studied in detail the capture of airborne magnetic dust by permanent magnets using a computational fluid dynamics (CFD) model supported by laboratory...

  4. A dual mode targeting probe for distinguishing HER2-positive breast cancer cells using silica-coated fluorescent magnetic nanoparticles

    Science.gov (United States)

    Li, Jia; An, Yan-Li; Zang, Feng-Chao; Zong, Shen-Fei; Cui, Yi-Ping; Teng, Gao-Jun

    2013-10-01

    We report a composite nanoprobe based on silica-coated magnetic nanoparticles (NPs) for distinguishing breast cancers at different HER2 statuses. The nanoprobe has a core-shell structure, with Fe3O4 NPs as the magnetic core and dye-embedded silica as the fluorescent shell, whose average size is about 150 nm. Besides, the outmost surfaces of the probes were modified with specific antibodies to endow the probe with a targeting ability. With such a structure, the nanoprobe can accomplish dual mode targeting of human breast cancer cells based on fluorescence and magnetic resonance imaging (MRI). In the experiments, three human breast cancer cell lines were used to test the targeting ability of the nanoprobe. Specifically, SKBR3 cells with a high HER2 expression level were used as the model target cells, while MCF7 cells with a lower HER2 expression levels and HER2-negative MDA-MB-231 cells were used as the controls. Both the fluorescence and MRI imaging results confirmed that the nanoprobe can distinguish three cancer cell lines with different HER2 expression levels. With the dual mode imaging and specific targeting properties, we anticipate that the presented nanoprobe may have a great potential in the diagnosis and treatment of cancerous diseases.

  5. Attitude dynamics of gyrostat-satellites under control by magnetic actuators at small perturbations

    Science.gov (United States)

    Doroshin, Anton V.

    2017-08-01

    The angular motion of gyrostat-satellites with one axial rotor is considered under control by magnetic actuators and at the action of small polyharmonic perturbations of the own dipole magnetic moment's components which are created proportionally to components of the angular velocity of the satellite. The attitude dynamics is investigated in conditions of the coincidence of the vector of magnetic induction of the external magnetic field and the initial angular momentum vector of the satellite. General and heteroclinic analytical solutions are obtained for dynamical parameters at the relative smallness of the magnetic torques. The chaotic regimes are examined on the base of the Melnikov method and Poincaré sections.

  6. Dynamic transcription factor activity and networks during ErbB2 breast oncogenesis and targeted therapy.

    Science.gov (United States)

    Weiss, M S; Peñalver Bernabé, B; Shin, S; Asztalos, S; Dubbury, S J; Mui, M D; Bellis, A D; Bluver, D; Tonetti, D A; Saez-Rodriguez, J; Broadbelt, L J; Jeruss, J S; Shea, L D

    2014-12-01

    Tissue development and disease progression are multi-stage processes controlled by an evolving set of key regulatory factors, and identifying these factors necessitates a dynamic analysis spanning relevant time scales. Current omics approaches depend on incomplete biological databases to identify critical cellular processes. Herein, we present TRACER (TRanscriptional Activity CEll aRrays), which was employed to quantify the dynamic activity of numerous transcription factor (TFs) simultaneously in 3D and networks for TRACER (NTRACER), a computational algorithm that allows for cellular rewiring to establish dynamic regulatory networks based on activity of TF reporter constructs. We identified major hubs at various stages of culture associated with normal and abnormal tissue growth (i.e., ELK-1 and E2F1, respectively) and the mechanism of action for a targeted therapeutic, lapatinib, through GATA-1, which were confirmed in human ErbB2 positive breast cancer patients and human ErbB2 positive breast cancer cell lines that were either sensitive or resistant to lapatinib.

  7. Quantification of intra-fraction motion in breast radiotherapy using supine magnetic resonance imaging

    NARCIS (Netherlands)

    van Heijst, Tristan C F; Philippens, Mariëlle E P; Charaghvandi, Ramona K; den Hartogh, Mariska D; Lagendijk, JJW; van den Bongard, H J G Desirée; van Asselen, B

    2016-01-01

    In early-stage breast-cancer patients, accelerated partial-breast irradiation techniques (APBI) and hypofractionation are increasingly implemented after breast-conserving surgery (BCS). For a safe and effective radiation therapy (RT), the influence of intra-fraction motion during dose delivery becom

  8. DYNAMIC MAGNETIC RESONANCE IMAGING: PRELIMINARY PRESENTATION OF A TECHNIQUE

    Directory of Open Access Journals (Sweden)

    BRUNO DA COSTA ANCHESCHI

    Full Text Available ABSTRACT Objective: To evaluate morphometric variations of the cervical spine in patients with cervical spondylotic myelopathy (CSM using dynamic magnetic resonance imaging (MRI in neutral, flexion and extension positions. Methods: This is a prospective study of patients with CSM secondary to degenerative disease of the cervical spine. The morphometric parameters were evaluated using T2-weighted MRI sequences in the sagittal plane in neutral, flexion and extension position of the neck. The parameters studied were the anterior length of the spinal cord (ALSC, the posterior length of the spinal cord (PLSC, the diameter of the vertebral canal (DVC and the diameter of the spinal cord (DSC. Results: The ALSC and PLSC were longer in flexion than in extension and neutral position, with statistically significant difference between the flexion and extension position. The DVC and the DSC were greater in flexion than in extension and neutral position, however, there was no statistically significant difference when they were compared in the neutral, flexion and extension positions. Conclusion: Dynamic MRI allows to evaluate morphometric variations in the cervical spinal canal in patients with cervical spondylotic myelopathy.

  9. Toxicity evaluation of magnetic hyperthermia induced by remote actuation of magnetic nanoparticles in 3D micrometastasic tumor tissue analogs for triple negative breast cancer.

    Science.gov (United States)

    Stocke, Nathanael A; Sethi, Pallavi; Jyoti, Amar; Chan, Ryan; Arnold, Susanne M; Hilt, J Zach; Upreti, Meenakshi

    2017-03-01

    Magnetic hyperthermia as a treatment modality is acquiring increased recognition for loco-regional therapy of primary and metastatic lung malignancies by pulmonary delivery of magnetic nanoparticles (MNP). The unique characteristic of magnetic nanoparticles to induce localized hyperthermia in the presence of an alternating magnetic field (AMF) allows for preferential killing of cells at the tumor site. In this study we demonstrate the effect of hyperthermia induced by low and high dose of MNP under the influence of an AMF using 3D tumor tissue analogs (TTA) representing the micrometastatic, perfusion independent stage of triple negative breast cancer (TNBC) that infiltrates the lungs. While application of inhalable magnetic nanocomposite microparticles or magnetic nanocomposites (MnMs) to the micrometastatic TNBC model comprised of TTA generated from cancer and stromal cells, showed no measureable adverse effects in the absence of AMF-exposure, magnetic hyperthermia generated under the influence of an AMF in TTA incubated in a high concentration of MNP (1 mg/mL) caused significant increase in cellular death/damage with mechanical disintegration and release of cell debris indicating the potential of these inhalable composites as a promising approach for thermal treatment of diseased lungs. The novelty and significance of this study lies in the development of methods to evaluate in vitro the application of inhalable composites containing MNPs in thermal therapy using a physiologically relevant metastatic TNBC model representative of the microenvironmental characteristics in secondary lung malignancies.

  10. Scale-free brain dynamics under physical and psychological distress: pre-treatment effects in women diagnosed with breast cancer.

    Science.gov (United States)

    Churchill, Nathan W; Cimprich, Bernadine; Askren, Mary K; Reuter-Lorenz, Patricia A; Jung, Mi Sook; Peltier, Scott; Berman, Marc G

    2015-03-01

    Stressful life events are related to negative outcomes, including physical and psychological manifestations of distress, and behavioral deficits. Patients diagnosed with breast cancer report impaired attention and working memory prior to adjuvant therapy, which may be induced by distress. In this article, we examine whether brain dynamics show systematic changes due to the distress associated with cancer diagnosis. We hypothesized that impaired working memory is associated with suppression of "long-memory" neuronal dynamics; we tested this by measuring scale-free ("fractal") brain dynamics, quantified by the Hurst exponent (H). Fractal scaling refers to signals that do not occur at a specific time-scale, possessing a spectral power curve P(f)∝ f(-β); they are "long-memory" processes, with significant autocorrelations. In a BOLD functional magnetic resonance imaging study, we scanned three groups during a working memory task: women scheduled to receive chemotherapy or radiotherapy and aged-matched controls. Surprisingly, patients' BOLD signal exhibited greater H with increasing intensity of anticipated treatment. However, an analysis of H and functional connectivity against self-reported measures of psychological distress (Worry, Anxiety, Depression) and physical distress (Fatigue, Sleep problems) revealed significant interactions. The modulation of (Worry, Anxiety) versus (Fatigue, Sleep Problems, Depression) showed the strongest effect, where higher worry and lower fatigue was related to reduced H in regions involved in visuospatial search, attention, and memory processing. This is also linked to decreased functional connectivity in these brain regions. Our results indicate that the distress associated with cancer diagnosis alters BOLD scaling, and H is a sensitive measure of the interaction between psychological versus physical distress.

  11. Calculation of static and dynamic linear magnetic response in approximate time-dependent density functional theory.

    Science.gov (United States)

    Krykunov, Mykhaylo; Autschbach, Jochen

    2007-01-14

    We report implementations and results of time-dependent density functional calculations (i) of the frequency-dependent magnetic dipole-magnetic dipole polarizability, (ii) of the (observable) translationally invariant linear magnetic response, and (iii) of a linear intensity differential (LID) which includes the dynamic dipole magnetizability. The density functional calculations utilized density fitting. For achieving gauge-origin independence we have employed time-periodic magnetic-field-dependent basis functions as well as the dipole velocity gauge, and have included explicit density-fit related derivatives of the Coulomb potential. We present the results of calculations of static and dynamic magnetic dipole-magnetic dipole polarizabilities for a set of small molecules, the LID for the SF6 molecule, and dispersion curves for M-hexahelicene of the origin invariant linear magnetic response as well as of three dynamic polarizabilities: magnetic dipole-magnetic dipole, electric dipole-electric dipole, and electric dipole-magnetic dipole. We have also performed comparison of the linear magnetic response and magnetic dipole-magnetic dipole polarizability over a wide range of frequencies for H2O and SF6.

  12. Comparison of the diagnostic performance of digital breast tomosynthesis and magnetic resonance imaging added to digital mammography in women with known breast cancers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Won Hwa; Chang, Jung Min; Moon, Woo Kyung [Seoul National University Hospital, Department of Radiology, 101 Daehangno, Jongno-gu, Seoul (Korea, Republic of); Moon, Hyeong-Gon [Seoul National University Hospital, Department of Surgery, Seoul (Korea, Republic of); Yi, Ann [Seoul National University Hospital, Department of Radiology, Gangnan Healthcare Center, Seoul (Korea, Republic of); Koo, Hye Ryoung [Hanyang University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Gweon, Hye Mi [Yonsei University College of Medicine, Department of Radiology, Gangnam Severance Hospital, Seoul (Korea, Republic of)

    2016-06-15

    To compare the diagnostic performance of digital breast tomosynthesis (DBT) and magnetic resonance imaging (MRI) added to mammography in women with known breast cancers. Three radiologists independently reviewed image sets of 172 patients with 184 cancers; mammography alone, DBT plus mammography and MRI plus mammography, and scored for cancer probability using the Breast Imaging Reporting and Data System (BI-RADS). Jack-knife alternative free-response receiver-operating characteristic (JAFROC), which allows diagnostic performance estimation using single lesion as a statistical unit in a cancer-only population, was used. Sensitivity and positive predictive value (PPV) were compared using the McNemar and Fisher-exact tests. The JAFROC figures of merit (FOMs) was lower in DBT plus mammography (0.937) than MRI plus mammography (0.978, P = 0.0006) but higher than mammography alone (0.900, P = 0.0013). The sensitivity was lower in DBT plus mammography (88.2 %) than MRI plus mammography (97.8 %) but higher than mammography alone (78.3 %, both P < 0.0001). The PPV was significantly higher in DBT plus mammography (93.3 %) than MRI plus mammography (89.6 %, P = 0.0282). DBT provided lower diagnostic performance than MRI as an adjunctive imaging to mammography. However, DBT had higher diagnostic performance than mammography and higher PPV than MRI. (orig.)

  13. Anti-HER2 antibody and ScFvEGFR-conjugated antifouling magnetic iron oxide nanoparticles for targeting and magnetic resonance imaging of breast cancer

    Directory of Open Access Journals (Sweden)

    Chen H

    2013-10-01

    Full Text Available Hongwei Chen,1,* Liya Wang,1,2,* Qiqi Yu,1,2 Weiping Qian,3 Diana Tiwari,1 Hong Yi,4 Andrew Y Wang,5 Jing Huang,1,2 Lily Yang,3 Hui Mao1,2 1Department of Radiology and Imaging Sciences, 2Center for Systems Imaging, 3Department of Surgery, Emory University School of Medicine, 4Robert Apkarian Electron Microscopy Core, Emory University, Atlanta, GA, 5Ocean NanoTech LLC, Springdale, AK, USA *These authors contributed equally to this work Abstract: Antifouling magnetic iron oxide nanoparticles (IONPs coated with block copolymer poly(ethylene oxide-block-poly(γ-methacryloxypropyltrimethoxysilane (PEO-b-PγMPS were investigated for improving cell targeting by reducing nonspecific uptake. Conjugation of a HER2 antibody, Herceptin®, or a single chain fragment (ScFv of antibody against epidermal growth factor receptor (ScFvEGFR to PEO-b-PγMPS-coated IONPs resulted in HER2-targeted or EGFR-targeted IONPs (anti-HER2-IONPs or ScFvEGFR-IONPs. The anti-HER2-IONPs bound specifically to SK-BR-3, a HER2-overexpressing breast cancer cell line, but not to MDA-MB-231, a HER2-underexpressing cell line. On the other hand, the ScFvEGFR-IONPs showed strong reactivity with MDA-MB-231, an EGFR-positive human breast cancer cell line, but not with MDA-MB-453, an EGFR-negative human breast cancer cell line. Transmission electron microscopy revealed internalization of the receptor-targeted nanoparticles by the targeted cancer cells. In addition, both antibody-conjugated and non-antibody-conjugated IONPs showed reduced nonspecific uptake by RAW264.7 mouse macrophages in vitro. The developed IONPs showed a long blood circulation time (serum half-life 11.6 hours in mice and low accumulation in both the liver and spleen. At 24 hours after systemic administration of ScFvEGFR-IONPs into mice bearing EGFR-positive breast cancer 4T1 mouse mammary tumors, magnetic resonance imaging revealed signal reduction in the tumor as a result of the accumulation of the targeted IONPs

  14. Simulation of the modulation transfer function dependent on the partial Fourier fraction in dynamic contrast enhancement magnetic resonance imaging.

    Science.gov (United States)

    Takatsu, Yasuo; Ueyama, Tsuyoshi; Miyati, Tosiaki; Yamamura, Kenichirou

    2016-12-01

    The image characteristics in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) depend on the partial Fourier fraction and contrast medium concentration. These characteristics were assessed and the modulation transfer function (MTF) was calculated by computer simulation. A digital phantom was created from signal intensity data acquired at different contrast medium concentrations on a breast model. The frequency images [created by fast Fourier transform (FFT)] were divided into 512 parts and rearranged to form a new image. The inverse FFT of this image yielded the MTF. From the reference data, three linear models (low, medium, and high) and three exponential models (slow, medium, and rapid) of the signal intensity were created. Smaller partial Fourier fractions, and higher gradients in the linear models, corresponded to faster MTF decline. The MTF more gradually decreased in the exponential models than in the linear models. The MTF, which reflects the image characteristics in DCE-MRI, was more degraded as the partial Fourier fraction decreased.

  15. Effects of ELF magnetic fields on protein expression profile of human breast cancer cell MCF7

    Institute of Scientific and Technical Information of China (English)

    LI Han; ZENG Qunli; WENG Yu; LU Deqiang; JIANG Huai; XU Zhengping

    2005-01-01

    Extremely Low Frequency Magnetic Fields (ELF MF) has been considered as a "possible human carcinogen" by International Agency for Research on Cancer (IARC) while credible mechanisms of its carcinogenicity remain unknown. In this study, a proteomics approach was employed to investigate the changes of protein expression profile induced by ELF MF in human breast cancer cell line MCF7, in order to determine ELF MF-responsive proteins. MCF7 cells were exposed to 50 Hz, 0.4 mT ELF MF for 24 h and the changes of protein profile were examined using two dimensional electrophoresis. Up to 6 spots have been statistically significantly altered (their expression levels were changed at least 5 fold up or down) compared with sham-exposed group. 19 ones were only detected in exposure group while 19 ones were missing. Three proteins were identified by LC-IT Tandem MS as RNA binding protein regulatory subunit、Proteasome subunit beta type 7 precursor and Translationally Controlled Tumor Protein. Our finding showed that 50 Hz, 0.4 mT ELF MF alternates the protein profile of MCF7 cell and may affect many physiological functions of normal cell and 2-DE coupled with MS is a promising approach to elucidating cellular effects of electromagnetic fields.

  16. Targeted delivery of doxorubicin to breast cancer cells by magnetic LHRH chitosan bioconjugated nanoparticles.

    Science.gov (United States)

    Varshosaz, Jaleh; Hassanzadeh, Farshid; Aliabadi, Hojat Sadeghi; Khoraskani, Fatemeh Rabbani; Mirian, Mina; Behdadfar, Behshid

    2016-12-01

    The novel dual targeted nanoparticles loaded with doxorubicin (DOX) and magnetic nanoparticles (MNPs) were prepared for treatment of breast cancer. Nanoparticles were produced by a layer-by-layer technique and functionalized with a bioconjugate of chitosan-poly(methyl vinyl ether maleic acid)(PMVMA)-LHRH to target LHRH receptors. The successful production of chitosan-PMVMA copolymer and its conjugation to LHRH was confirmed by FTIR and (1)HNMR spectroscopy. Capillary electrophoresis analysis showed 72.51% LHRH conjugation efficiency. Transmission electron microscopy and thermogravimetric analysis showed the entrapment of the MNPs in the core of the nanoparticles and vibrating sample magnetometery confirmed their paramagnetic properties. The iron content of nanoparticles determined by inductively coupled plasma optical emission spectrometry showed to be between 3.5-84%. Particle size, zeta potential, drug entrapment and release efficiency of the nanoparticles were 88.1-182.6nm, 10-30mV, 62.3-87.6% and 79.8-83.4%, respectively. No significant protein binding was seen by nanoparticles. The MTT assay showed in LHRH positive cells of MCF-7 the IC50 of the drug reduced to about 2 fold compared to the free drug. By saturation of LHRH receptors the viable MCF7 cells increased significantly after exposure with the targeted nanoparticles. Therefore, the cellular uptake of the nanoparticles might be done by active endocytosis through the LHRH receptors. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Information flow and protein dynamics: the interplay between nuclear magnetic resonance spectroscopy and molecular dynamics simulations

    Science.gov (United States)

    Pastor, Nina; Amero, Carlos

    2015-01-01

    Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics, and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells. PMID:25999971

  18. Information Flow and Protein Dynamics: the Interplay Between Nuclear Magnetic Resonance Spectroscopy and Molecular Dynamics Simulations

    Directory of Open Access Journals (Sweden)

    Nina ePastor

    2015-05-01

    Full Text Available Proteins participate in information pathways in cells, both as links in the chain of signals, and as the ultimate effectors. Upon ligand binding, proteins undergo conformation and motion changes, which can be sensed by the following link in the chain of information. Nuclear magnetic resonance (NMR spectroscopy and molecular dynamics (MD simulations represent powerful tools for examining the time-dependent function of biological molecules. The recent advances in NMR and the availability of faster computers have opened the door to more detailed analyses of structure, dynamics and interactions. Here we briefly describe the recent applications that allow NMR spectroscopy and MD simulations to offer unique insight into the basic motions that underlie information transfer within and between cells.

  19. Signal enhancement ratio (SER) quantified from breast DCE-MRI and breast cancer risk

    Science.gov (United States)

    Wu, Shandong; Kurland, Brenda F.; Berg, Wendie A.; Zuley, Margarita L.; Jankowitz, Rachel C.; Sumkin, Jules; Gur, David

    2015-03-01

    Breast magnetic resonance imaging (MRI) is recommended as an adjunct to mammography for women who are considered at elevated risk of developing breast cancer. As a key component of breast MRI, dynamic contrast-enhanced MRI (DCE-MRI) uses a contrast agent to provide high intensity contrast between breast tissues, making it sensitive to tissue composition and vascularity. Breast DCE-MRI characterizes certain physiologic properties of breast tissue that are potentially related to breast cancer risk. Studies have shown that increased background parenchymal enhancement (BPE), which is the contrast enhancement occurring in normal cancer-unaffected breast tissues in post-contrast sequences, predicts increased breast cancer risk. Signal enhancement ratio (SER) computed from pre-contrast and post-contrast sequences in DCE-MRI measures change in signal intensity due to contrast uptake over time and is a measure of contrast enhancement kinetics. SER quantified in breast tumor has been shown potential as a biomarker for characterizing tumor response to treatments. In this work we investigated the relationship between quantitative measures of SER and breast cancer risk. A pilot retrospective case-control study was performed using a cohort of 102 women, consisting of 51 women who had diagnosed with unilateral breast cancer and 51 matched controls (by age and MRI date) with a unilateral biopsy-proven benign lesion. SER was quantified using fully-automated computerized algorithms and three SER-derived quantitative volume measures were compared between the cancer cases and controls using logistic regression analysis. Our preliminary results showed that SER is associated with breast cancer risk, after adjustment for the Breast Imaging Reporting and Data System (BI-RADS)-based mammographic breast density measures. This pilot study indicated that SER has potential for use as a risk factor for breast cancer risk assessment in women at elevated risk of developing breast cancer.

  20. Parameter estimation of breast tumour using dynamic neural network from thermal pattern

    Directory of Open Access Journals (Sweden)

    Elham Saniei

    2016-11-01

    Full Text Available This article presents a new approach for estimating the depth, size, and metabolic heat generation rate of a tumour. For this purpose, the surface temperature distribution of a breast thermal image and the dynamic neural network was used. The research consisted of two steps: forward and inverse. For the forward section, a finite element model was created. The Pennes bio-heat equation was solved to find surface and depth temperature distributions. Data from the analysis, then, were used to train the dynamic neural network model (DNN. Results from the DNN training/testing confirmed those of the finite element model. For the inverse section, the trained neural network was applied to estimate the depth temperature distribution (tumour position from the surface temperature profile, extracted from the thermal image. Finally, tumour parameters were obtained from the depth temperature distribution. Experimental findings (20 patients were promising in terms of the model’s potential for retrieving tumour parameters.

  1. Hybrid Molecular and Spin Dynamics Simulations for Ensembles of Magnetic Nanoparticles for Magnetoresistive Systems.

    Science.gov (United States)

    Teich, Lisa; Schröder, Christian

    2015-11-13

    The development of magnetoresistive sensors based on magnetic nanoparticles which are immersed in conductive gel matrices requires detailed information about the corresponding magnetoresistive properties in order to obtain optimal sensor sensitivities. Here, crucial parameters are the particle concentration, the viscosity of the gel matrix and the particle structure. Experimentally, it is not possible to obtain detailed information about the magnetic microstructure, i.e., orientations of the magnetic moments of the particles that define the magnetoresistive properties, however, by using numerical simulations one can study the magnetic microstructure theoretically, although this requires performing classical spin dynamics and molecular dynamics simulations simultaneously. Here, we present such an approach which allows us to calculate the orientation and the trajectory of every single magnetic nanoparticle. This enables us to study not only the static magnetic microstructure, but also the dynamics of the structuring process in the gel matrix itself. With our hybrid approach, arbitrary sensor configurations can be investigated and their magnetoresistive properties can be optimized.

  2. Experimental investigation on the dynamic mechanical properties of soft magnetic entangled metallic wire material

    Science.gov (United States)

    Ma, Yanhong; Zhang, Qicheng; Zhang, Dayi; Hu, Wenzhong; Hong, Jie

    2017-05-01

    This work describes the dynamic characteristics of a novel soft magnetic entangled metallic wire material(SM-EMWM) by the dynamic tests for the first time. The mechanical properties of three batches of SM-EMWMs with different porosities have been investigated under different dynamic loads in different magnetic field intensities. The result shows that its properties (storage modulus and loss factor) have commendably controllable magnetic responses in the magnetic field. In particular, the dynamic damping is more remarkable than its quasi-static performance, and the loss factor can be improved above 50% in the magnetic field of 500 mT. The results indicate that SM-EMWM as a magneto-sensitive smart material possesses a considerable application prospect for the active vibration control with variable stiffness and damping.

  3. Dynamic transcription factor networks in epithelial-mesenchymal transition in breast cancer models.

    Science.gov (United States)

    Siletz, Anaar; Schnabel, Michael; Kniazeva, Ekaterina; Schumacher, Andrew J; Shin, Seungjin; Jeruss, Jacqueline S; Shea, Lonnie D

    2013-01-01

    The epithelial-mesenchymal transition (EMT) is a complex change in cell differentiation that allows breast carcinoma cells to acquire invasive properties. EMT involves a cascade of regulatory changes that destabilize the epithelial phenotype and allow mesenchymal features to manifest. As transcription factors (TFs) are upstream effectors of the genome-wide expression changes that result in phenotypic change, understanding the sequential changes in TF activity during EMT provides rich information on the mechanism of this process. Because molecular interactions will vary as cells progress from an epithelial to a mesenchymal differentiation program, dynamic networks are needed to capture the changing context of molecular processes. In this study we applied an emerging high-throughput, dynamic TF activity array to define TF activity network changes in three cell-based models of EMT in breast cancer based on HMLE Twist ER and MCF-7 mammary epithelial cells. The TF array distinguished conserved from model-specific TF activity changes in the three models. Time-dependent data was used to identify pairs of TF activities with significant positive or negative correlation, indicative of interdependent TF activity throughout the six-day study period. Dynamic TF activity patterns were clustered into groups of TFs that change along a time course of gene expression changes and acquisition of invasive capacity. Time-dependent TF activity data was combined with prior knowledge of TF interactions to construct dynamic models of TF activity networks as epithelial cells acquire invasive characteristics. These analyses show EMT from a unique and targetable vantage and may ultimately contribute to diagnosis and therapy.

  4. Dynamic transcription factor networks in epithelial-mesenchymal transition in breast cancer models.

    Directory of Open Access Journals (Sweden)

    Anaar Siletz

    Full Text Available The epithelial-mesenchymal transition (EMT is a complex change in cell differentiation that allows breast carcinoma cells to acquire invasive properties. EMT involves a cascade of regulatory changes that destabilize the epithelial phenotype and allow mesenchymal features to manifest. As transcription factors (TFs are upstream effectors of the genome-wide expression changes that result in phenotypic change, understanding the sequential changes in TF activity during EMT provides rich information on the mechanism of this process. Because molecular interactions will vary as cells progress from an epithelial to a mesenchymal differentiation program, dynamic networks are needed to capture the changing context of molecular processes. In this study we applied an emerging high-throughput, dynamic TF activity array to define TF activity network changes in three cell-based models of EMT in breast cancer based on HMLE Twist ER and MCF-7 mammary epithelial cells. The TF array distinguished conserved from model-specific TF activity changes in the three models. Time-dependent data was used to identify pairs of TF activities with significant positive or negative correlation, indicative of interdependent TF activity throughout the six-day study period. Dynamic TF activity patterns were clustered into groups of TFs that change along a time course of gene expression changes and acquisition of invasive capacity. Time-dependent TF activity data was combined with prior knowledge of TF interactions to construct dynamic models of TF activity networks as epithelial cells acquire invasive characteristics. These analyses show EMT from a unique and targetable vantage and may ultimately contribute to diagnosis and therapy.

  5. Nuclear magnetic resonance studies of macroscopic morphology and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Barrall, Geoffrey Alden [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1995-09-01

    Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utility of a number of new and novel techniques using ideal systems primarily as a proof of principle. By taking advantage of the analogy between NMR imaging and diffraction, one may simplify the experiments necessary for characterizing the statistical properties of the sample morphology. For a sample composed of many small features, e.g. a porous medium, the NMR diffraction techniques take advantage of both the narrow spatial range and spatial isotropy of the sample`s density autocorrelation function to obtain high resolution structural information in considerably less time than that required by conventional NMR imaging approaches. The time savings of the technique indicates that NMR diffraction is capable of finer spatial resolution than conventional NMR imaging techniques. Radio frequency NMR imaging with a coaxial resonator represents the first use of cylindrically symmetric field gradients in imaging. The apparatus as built has achieved resolution at the micron level for water samples, and has the potential to be very useful in the imaging of circularly symmetric systems. The study of displacement probability densities in flow through a random porous medium has revealed the presence of features related to the interconnectedness of the void volumes. The pulsed gradient techniques used have proven successful at measuring flow properties for time and length scales considerably shorter than those studied by more conventional techniques.

  6. Vlasov simulations of electron hole dynamics in inhomogeneous magnetic field

    Science.gov (United States)

    Kuzichev, Ilya; Vasko, Ivan; Agapitov, Oleksiy; Mozer, Forrest; Artemyev, Anton

    2017-04-01

    Electron holes (EHs) or phase space vortices are solitary electrostatic waves existing due to electrons trapped within EH electrostatic potential. Since the first direct observation [1], EHs have been widely observed in the Earth's magnetosphere: in reconnecting current sheets [2], injection fronts [3], auroral region [4], and many other space plasma systems. EHs have typical spatial scales up to tens of Debye lengths, electric field amplitudes up to hundreds of mV/m and propagate along magnetic field lines with velocities of about electron thermal velocity [5]. The role of EHs in energy dissipation and supporting of large-scale potential drops is under active investigation. The accurate interpretation of spacecraft observations requires understanding of EH evolution in inhomogeneous plasma. The critical role of plasma density gradients in EH evolution was demonstrated in [6] using PIC simulations. Interestingly, up to date no studies have addressed a role of magnetic field gradients in EH evolution. In this report, we use 1.5D gyrokinetic Vlasov code to demonstrate the critical role of magnetic field gradients in EH dynamics. We show that EHs propagating into stronger (weaker) magnetic field are decelerated (accelerated) with deceleration (acceleration) rate dependent on the magnetic field gradient. Remarkably, the reflection points of decelerating EHs are independent of the average magnetic field gradient in the system and depend only on the EH parameters. EHs are decelerated (accelerated) faster than would follow from the "quasi-particle" concept assuming that EH is decelerated (accelerated) entirely due to the mirror force acting on electrons trapped within EH. We demonstrate that EH propagation in inhomogeneous magnetic fields results in development of a net potential drop along an EH, which depends on the magnetic field gradient. The revealed features will be helpful for interpreting spacecraft observations and results of advanced particle simulations. In

  7. Dynamic in situ visualization of voltage-driven magnetic domain evolution in multiferroic heterostructures

    Science.gov (United States)

    Gao, Ya; Hu, Jia-Mian; Wu, Liang; Nan, C. W.

    2015-12-01

    Voltage control of magnetism in multiferroic heterostructures provides a promising solution to the excessive heating in spintronic devices. Direct observation of voltage-modulated magnetic domain evolution dynamics is desirable for studying the mechanism of the voltage control of magnetism at mesoscale, but has remained challenging. Here we explored a characterization method for the dynamic in situ evolution of pure voltage modulated magnetic domains in the heterostructures by employing the scanning Kerr microscopy function in the magneto optic Kerr effect system. The local magnetization reorientation of a Ni/PMN-PT heterostructure were characterized under sweeping applied voltage on the PMN-PT single crystal, and the results show that the magnetization rotation angle in the local regions is much greater than that obtained from macroscopic magnetization hysteresis loops.

  8. Electron dynamics in collisionless magnetic reconnection with a PIC simulation

    Institute of Scientific and Technical Information of China (English)

    GUO Jun

    2009-01-01

    Two-dimensional particle-in-cell (PIC) simulation is used to investigate electron dynamics in colli-sionless magnetic reconnection, and the proton/electron mass ratio is taken to be ml/me = 256. The results show that the presence of a strong initial guide field will change the direction of the electron flow. The electron density cavities and the parallel electric field can be found in the electron inflow re-gion along the separatrix, and the electron inflow and density cavities only appear in the second and fourth quadrants. What is different from the results with a smaller mass ratio is that new structures appear in the diffusion region near the X line: (1) Narrow regions of density enhancement and density cavities can be found synchronously in this region; and (2) corresponding to the electron density changes near the X line, the strong parallel electric fields are found to occur in the first and third quadrants. These electric fields perhaps play a more important role in acceleration and heating elec-trons than those fields located in the density cavities.

  9. Assessing Tumor Angiogenesis with Dynamic Contrast Enhanced Magnetic Resonance Imaging

    Science.gov (United States)

    Esparza-Coss, Emilio; Jackson, Edward F.

    2006-09-01

    Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a method able of assessing microvascular changes at high spatial resolution and without ionizing radiation. The microcirculation and structure of tumors are fundamentally chaotic in that tumor-derived factors stimulate the endothelial cells to form new small vessels (angiogenesis) and this vasculature deviates markedly from normal hierarchical branching patterns. The tumor-induced microvascular changes lead to blood flow that is both spatially and temporally more heterogeneous than the efficient and uniform perfusion of normal organs and tissues. DCE-MRI allows for the assessment of perfusion and permeability of the tumor microvasculature, including the network of vessels with diameters less than 100 μm, which are beyond the resolution of conventional angiograms. The microvessel permeability to small molecular weight contrast media as well as measures of tumor response can be assessed with different analysis techniques ranging from simple measures of enhancement to pharmacokinetic models. In this work, such DCE-MRI analysis techniques are discussed.

  10. Local Dynamics and Global Size Coupling during Magnetic Reconnection

    Science.gov (United States)

    Jacobson, C. M.; Breslau, J. A.; Jardin, S. C.; Ji, H.

    2008-11-01

    Magnetic reconnection is an important physical process not only in small systems such as laboratory plasmas, but also in large systems such as solar flares. The reconnection rate increases with resistivity η and decreases with the current sheet length L. Recent experimental results suggest that these parameters are not independent, but anti-correlate such that ηL is kept roughly constant; thus the reconnection rate is a function of both local dynamics and global size [1]. In order to verify these results and further extend the system size, a numerical MHD model [2] is used. This code allows simulation of either two-fluid or single-fluid resistive MHD reconnection of colliding flux tubes on a 2D grid. The resistivity and system size are systematically varied, and scalings of the ion skin depth, collisionality, and reconnection rate due to these quantities are presented. Results are compared to experimental data, and findings are projected to solar flare scales. [1] A. Kuritsyn et al. Geophys. Res. Lett. 34, L16106 (2007) [2] J. A. Breslau and S. C. Jardin, Comput. Phys. Commun. 151, 8 (2003)

  11. Nonlinear dynamics of magnetic islands imbedded in small-scale turbulence.

    Science.gov (United States)

    Muraglia, M; Agullo, O; Benkadda, S; Garbet, X; Beyer, P; Sen, A

    2009-10-02

    The nonlinear dynamics of magnetic tearing islands imbedded in a pressure gradient driven turbulence is investigated numerically in a reduced magnetohydrodynamic model. The study reveals regimes where the linear and nonlinear phases of the tearing instability are controlled by the properties of the pressure gradient. In these regimes, the interplay between the pressure and the magnetic flux determines the dynamics of the saturated state. A secondary instability can occur and strongly modify the magnetic island dynamics by triggering a poloidal rotation. It is shown that the complex nonlinear interaction between the islands and turbulence is nonlocal and involves small scales.

  12. Nonlinear Dynamics of Magnetic Islands Imbedded in Small-Scale Turbulence

    CERN Document Server

    Muraglia, Magali; Benkadda, Sadruddin; Garbet, Xavier; Beyer, P; Sen, Abhijit; 10.1103/PhysRevLett.103.145001

    2011-01-01

    The nonlinear dynamics of magnetic tearing islands imbedded in a pressure gradient driven turbulence is investigated numerically in a reduced magnetohydrodynamic model. The study reveals regimes where the linear and nonlinear phases of the tearing instability are controlled by the properties of the pressure gradient. In these regimes, the interplay between the pressure and the magnetic flux determines the dynamics of the saturated state. A secondary instability can occur and strongly modify the magnetic island dynamics by triggering a poloidal rotation. It is shown that the complex nonlinear interaction between the islands and turbulence is nonlocal and involves small scales.

  13. Enhanced resting-state dynamics of the hemoglobin signal as a novel biomarker for detection of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Graber, Harry L., E-mail: harry.graber@downstate.edu; Xu, Yong; Barbour, Randall L. [SUNY Downstate Medical Center, Brooklyn, New York 11203 (United States); NIRx Medical Technologies, LLC, Glen Head, New York 11545 (United States); Al abdi, Rabah [Department of Biomedical Engineering, Jordan University of Science and Technology, Irbid 22110 (Jordan); Asarian, Armand P.; Pappas, Peter J. [The Brooklyn Hospital Center, Brooklyn, New York 11201 (United States); Dresner, Lisa [SUNY Downstate Medical Center, Brooklyn, New York 11203 (United States); Patel, Naresh [Kaiser Permanente-Modesto Medical Center, Modesto, California 95356 (United States); Jagarlamundi, Kuppuswamy [Sarah Bush Lincoln Regional Cancer Center, 1000 Health Center Drive, Mattoon, Illinois 61938 (United States); Solomon, William B. [Maimonides Medical Center, Brooklyn, New York 11219 (United States)

    2015-11-15

    Purpose: The work presented here demonstrates an application of diffuse optical tomography (DOT) to the problem of breast-cancer diagnosis. The potential for using spatial and temporal variability measures of the hemoglobin signal to identify useful biomarkers was studied. Methods: DOT imaging data were collected using two instrumentation platforms the authors developed, which were suitable for exploring tissue dynamics while performing a simultaneous bilateral exam. For each component of the hemoglobin signal (e.g., total, oxygenated), the image time series was reduced to eight scalar metrics that were affected by one or more dynamic properties of the breast microvasculature (e.g., average amplitude, amplitude heterogeneity, strength of spatial coordination). Receiver-operator characteristic (ROC) analyses, comparing groups of subjects with breast cancer to various control groups (i.e., all noncancer subjects, only those with diagnosed benign breast pathology, and only those with no known breast pathology), were performed to evaluate the effect of cancer on the magnitudes of the metrics and of their interbreast differences and ratios. Results: For women with known breast cancer, simultaneous bilateral DOT breast measures reveal a marked increase in the resting-state amplitude of the vasomotor response in the hemoglobin signal for the affected breast, compared to the contralateral, noncancer breast. Reconstructed 3D spatial maps of observed dynamics also show that this behavior extends well beyond the tumor border. In an effort to identify biomarkers that have the potential to support clinical aims, a group of scalar quantities extracted from the time series measures was systematically examined. This analysis showed that many of the quantities obtained by computing paired responses from the bilateral scans (e.g., interbreast differences, ratios) reveal statistically significant differences between the cancer-positive and -negative subject groups, while the

  14. Biodegradable Chitosan Magnetic Nanoparticle Carriers for Sub-Cellular Targeting Delivery of Artesunate for Efficient Treatment of Breast Cancer

    Science.gov (United States)

    Subramanian, Natesan; Abimanyu, Sugumaran; Vinoth, Jeevanesan; Sekar, Ponnusamy Chandra

    2010-12-01

    Artesunate is a semi-synthetic derivative of artemisinin, the active principle extracted from Artemisia annua. It possesses good anti-proliferative activity and anti-angiogenic activity with very low toxicity to normal healthy cells. The drawback of most cancer drugs is their inability to accumulate selectively in the cancerous cells. So, large quantities of doses have to be administered to get the required therapeutic concentration in the target site and it resulted in many serious side effects due to the exposure of healthy cells to higher concentrations of cytotoxic drugs. The problem may be solved by selectively and quantitatively accumulating the drug at target site using magnetic nanoparticles guided by an externally applied magnetic field. A modest attempt has been made in this present study, the artesunate magnetic nanoparticle was successfully formulated using two forms of chitosan and evaluated for its in-vitro characteristics like surface morphology, particle size and distribution, zeta potential, magnetic susceptibility, encapsulation efficiency, loading capacity and in-vitro drug release. The synthesized magnetite size was 73 nm and the size of developed magnetic nanoparticles of artesunate was in the range of 90 to 575 nm. Acetic acid soluble chitosan at low concentration exhibit highest encapsulation efficiency and drug loading whereas increase in water soluble chitosan concentration increases the encapsulation efficiency and drug loading in formulations. The developed chitosan magnetic nanoparticles of artesunate shows better release characteristics and may be screened for its in-vivo breast cancer activity.

  15. The mechanism of vortex switching in magnetic nanodots under circular magnetic field. II. The dynamics of spin plaquette with vortex

    CERN Document Server

    Kovalev, A S

    2003-01-01

    A plaquette spin system in a vortex configuration is considered analytically and numerically to treat theoretically the vortex switching in magnetic nanodots due to the action of external circular magnetic field. The initial (linear) stage of the switching is analyzed. The analytical results obtained confirm the numerical data on the plaquette dynamics. Both the numerical analysis and the analytical consideration of the initial activation stage show the importance of taking into account the system azimuthal modes. At the frequencies of these modes the most rapid amplification of the vortex energy and the total out-of-plane magnetization occurs. The growth of the modes amplitudes gives rise to a parametrical activation of the low-frequency symmetric mode, and in turn causes the vortex switching. The results obtained provide a qualitative explanation of the numerical data on vortex switching in large-sized magnetic systems and may be used in experiments on guided effect on vortex polarization in magnetic nanodo...

  16. A dynamic macromodel for distributed parameter magnetic microactuators

    Institute of Scientific and Technical Information of China (English)

    Fang Yu-Ming; Huang Qing-An; Li Wei-Hua

    2008-01-01

    This paper presents a reduced-order model to describe the mechanical behaviour of microbeam-based magnetic devices.The integration for magnetic force is calculated by dividing the microbeam into several segments,and the nonlinear equation set has been developed based on the magnetic circuit principle.In comparison with previous models,the present macromodel accounts for both the micro-magnetic-core reluctance and the coupling between the beam deflection and magnetic force.This mazromodel is validated by comparing with the experimental results available in some papers and finite-element solutions.

  17. Exploring the magnetization dynamics of NiFe/Pt multilayers in flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Corrêa, M.A., E-mail: marciocorrea@dfte.ufrn.br [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Dutra, R.; Marcondes, T.L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil); Mori, T.J.A. [Laboratório Nacional de Luz Síncrotron, Rua Giuseppe Máximo Scolfaro, 1000, Guará, 13083-100 Campinas, SP (Brazil); Bohn, F. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Sommer, R.L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil)

    2016-09-15

    Highlights: • Magnetic properties of multilayers grown onto flexible substrates were investigated. • Experimental and theoretical magnetization dynamics results are presented. • The flexible substrates become promising candidate for rf-frequency devices. - Abstract: We investigate the structural and magnetic properties, and the magnetization dynamics in Ni{sub 81}Fe{sub 19}/Pt multilayer systems grown onto rigid and flexible substrates. The structural characterization shows evidence of a superlattice behavior, while the quasi-static magnetization characterization reveal a weak magnetic anisotropy induced in the multilayers. The magnetization dynamics is investigated through the magnetoimpedance effect. We employ a theoretical approach to describe the experimental magnetoimpedance effect and verify the influence of the effective damping parameter on the magnetization dynamics. Experimental data and theoretical results are in agreement and suggest that the multilayers present high effective damping parameter. Moreover, our experiments raise an interesting issue on the possibility of achieving considerable MI% values, even for systems with weak magnetic anisotropy and high damping parameter grown onto flexible substrates.

  18. Photospheric and Subphotospheric Dynamics of Emerging Magnetic Flux

    CERN Document Server

    Kosovichev, A G

    2009-01-01

    Magnetic fields emerging from the Sun's interior carry information about physical processes of magnetic field generation and transport in the convection zone. Soon after appearance on the solar surface the magnetic flux gets concentrated in sunspot regions and causes numerous active phenomena on the Sun. This paper discusses some properties of the emerging magnetic flux observed on the solar surface and in the interior. A statistical analysis of variations of the tilt angle of bipolar magnetic regions during the emergence shows that the systematic tilt with respect to the equator (the Joy's law) is most likely established below the surface. However, no evidence of the dependence of the tilt angle on the amount of emerging magnetic flux, predicted by the rising magnetic flux rope theories, is found. Analysis of surface plasma flows in a large emerging active region reveals strong localized upflows and downflows at the initial phase of emergence but finds no evidence for large-scale flows indicating future appe...

  19. Magnetic forces and magnetized biomaterials provide dynamic flux information during bone regeneration.

    Science.gov (United States)

    Russo, Alessandro; Bianchi, Michele; Sartori, Maria; Parrilli, Annapaola; Panseri, Silvia; Ortolani, Alessandro; Sandri, Monica; Boi, Marco; Salter, Donald M; Maltarello, Maria Cristina; Giavaresi, Gianluca; Fini, Milena; Dediu, Valentin; Tampieri, Anna; Marcacci, Maurilio

    2016-03-01

    The fascinating prospect to direct tissue regeneration by magnetic activation has been recently explored. In this study we investigate the possibility to boost bone regeneration in an experimental defect in rabbit femoral condyle by combining static magnetic fields and magnetic biomaterials. NdFeB permanent magnets are implanted close to biomimetic collagen/hydroxyapatite resorbable scaffolds magnetized according to two different protocols . Permanent magnet only or non-magnetic scaffolds are used as controls. Bone tissue regeneration is evaluated at 12 weeks from surgery from a histological, histomorphometric and biomechanical point of view. The reorganization of the magnetized collagen fibers under the effect of the static magnetic field generated by the permanent magnet produces a highly-peculiar bone pattern, with highly-interconnected trabeculae orthogonally oriented with respect to the magnetic field lines. In contrast, only partial defect healing is achieved within the control groups. We ascribe the peculiar bone regeneration to the transfer of micro-environmental information, mediated by collagen fibrils magnetized by magnetic nanoparticles, under the effect of the static magnetic field. These results open new perspectives on the possibility to improve implant fixation and control the morphology and maturity of regenerated bone providing "in site" forces by synergically combining static magnetic fields and biomaterials.

  20. Computer-aided diagnosis for diagnostically challenging breast lesions in DCE-MRI based on image registration and integration of morphologic and dynamic characteristics

    Science.gov (United States)

    Retter, Felix; Plant, Claudia; Burgeth, Bernhard; Botella, Guillermo; Schlossbauer, Thomas; Meyer-Bäse, Anke

    2013-12-01

    Diagnostically challenging lesions comprise both foci (small lesions) and non-mass-like enhancing lesions and pose a challenge to current computer-aided diagnosis systems. Motion-based artifacts lead in dynamic contrast-enhanced breast magnetic resonance to diagnostic misinterpretation; therefore, motion compensation represents an important prerequisite to automatic lesion detection and diagnosis. In addition, the extraction of pertinent kinetic and morphologic features as lesion descriptors is an equally important task. In the present paper, we evaluate the performance of a computer-aided diagnosis system consisting of motion correction, lesion segmentation, and feature extraction and classification. We develop a new feature extractor, the radial Krawtchouk moment, which guarantees rotation invariance. Many novel feature extraction techniques are proposed and tested in conjunction with lesion detection. Our simulation results have shown that motion compensation combined with Minkowski functionals and Bayesian classifier can improve lesion detection and classification.

  1. A feasibility study of magnetic resonance imaging of silicone breast implants in Finland

    DEFF Research Database (Denmark)

    Kulmala, Ilona; Boice, John D; McLaughlin, Joseph K

    2005-01-01

    Cosmetic breast implants have become increasingly popular throughout the world. However, there is insufficient knowledge about the frequency and severity of local complications such as rupture and capsular contracture. A pilot study of 25 Finnish women with 50 cosmetic breast implants was organized...

  2. Magnetic Resonance-Guided High Intensity Focused Ultrasound Ablation of Breast Cancer

    NARCIS (Netherlands)

    Knuttel, Floor; van den Bosch, Maurice A A J

    2016-01-01

    This chapter describes several aspects of MR-HIFU treatment for breast cancer. The current and future applications, technical developments and clinical results are discussed. MR-HIFU ablation is under investigation for the treatment of breast cancer, but is not yet ready for clinical implementation.

  3. Final Report: Nanoscale Dynamical Heterogeneity in Complex Magnetic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kevan, Stephen [Univ. of Oregon, Eugene, OR (United States)

    2016-05-27

    A magnetic object can be demagnetized by dropping it on a hard surface, but what does ‘demagnetized’ actually mean? In 1919 Heinrich Barkhausen proved the existence of magnetic domains, which are regions of uniform magnetization that are much larger than atoms but much smaller than a macroscopic object. A material is fully magnetized when domain magnetizations are aligned, while it is demagnetized when the domain magnetizations are randomly oriented and the net magnetization is zero. The heterogeneity of a demagnetized object leads to interesting questions. Magnets are unstable when their poles align, and stable when their poles anti-align, so why is the magnetized state ever stable? What do domains look like? What is the structure of a domain wall? How does the magnetized state transform to the demagnetized state? How do domains appear and disappear? What are the statistical properties of domains and how do these vary as the domain pattern evolves? Some of these questions remain the focus of intense study nearly a century after Barkhausen’s discovery. For example, just a few years ago a new kind of magnetic texture called a skyrmion was discovered. A skyrmion is a magnetic domain that is a nanometer-scale, topologically protected vortex. ‘Topologically protected’ means that skyrmions are hard to destroy and so are stable for extended periods. Skyrmions are characterized by integral quantum numbers and are observed to move with little dissipation and so could store and process information with very low power input. Our research project uses soft x-rays, which offer very high magnetic contrast, to probe magnetic heterogeneity and to measure how it evolves in time under external influences. We will condition a soft x-ray beam so that the wave fronts will be coherent, that is, they will be smooth and well-defined. When coherent soft x-ray beam interacts with a magnetic material, the magnetic heterogeneity is imprinted onto the wave fronts and projected into

  4. Research on electromagnetic relay's dynamic characteristics disturbed by uniform static magnetic field

    Institute of Scientific and Technical Information of China (English)

    Guo-fu ZHAI; Qi-ya WANG; Wan-bin REN

    2008-01-01

    Electromagnetic relay is a widely used apparatus which usually works in a magnetic disturbance environment. To evaluate its electromagnetic compatibility (EMC) in a static magnetic field, dynamic characteristics of a clapper relay in a uniform static magnetic field situation based on the finite element method (FEM) is studied. Influences of the magnetic field on dynamic parameters (delay time, pick-up time, end pressure, and final velocity) as well as a situation in which the relay cannot function normally are analyzed. Simulation reveals that the external magnetic field which weakens the relay's air-gap field has a greater influence on the relay's dynamic parameters than the one strengthening the field. The validity of the simulation is verified by measured results of coil current and armature displacement.

  5. Orientational order and translational dynamics of magnetic particle assemblies in liquid crystals.

    Science.gov (United States)

    Peroukidis, Stavros D; Klapp, Sabine H L

    2016-08-10

    Implementing extensive molecular dynamics simulations we explore the organization of magnetic particle assemblies (clusters) in a uniaxial liquid crystalline matrix comprised of rodlike particles. The magnetic particles are modelled as soft dipolar spheres with diameter significantly smaller than the width of the rods. Depending on the dipolar strength coupling the magnetic particles arrange into head-to-tail configurations forming various types of clusters including rings (closed loops) and chains. In turn, the liquid crystalline matrix induces long range orientational ordering to these structures and promotes their diffusion along the director of the phase. Different translational dynamics are exhibited as the liquid crystalline matrix transforms either from isotropic to nematic or from nematic to smectic state. This is caused due to different collective motion of the magnetic particles into various clusters in the anisotropic environments. Our results offer a physical insight for understanding both the structure and dynamics of magnetic particle assemblies in liquid crystalline matrices.

  6. Optimal Controller Tested for a Magnetically Suspended Five-Axis Dynamic Spin Rig

    Science.gov (United States)

    Choi, Benjamin B.

    2003-01-01

    NASA Glenn Research Center's Structural Mechanics and Dynamics Branch has developed a fully suspended magnetic bearing system for their Dynamic Spin Rig, which performs vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust magnetic bearing and the associated control system were integrated into the Dynamic Spin Rig to provide magnetic excitation as well as noncontact magnetic suspension of the 35-lb vertical rotor with blades to induce turbomachinery blade vibration (ref. 1). The new system can provide longer run times at higher speeds and larger vibration amplitudes for rotating blades. Also, it was proven that bearing mechanical life was substantially extended and flexibility was increased in the excitation orientation (direction and phasing).

  7. Electrical detection of magnetization dynamics in an ultrathin CoFeB film with perpendicular anisotropy

    Science.gov (United States)

    Kong, Wenwen; Fan, Xiaolong; Zhou, Hengan; Cao, Jiangwei; Guo, Dangwei; Gui, Y. S.; Hu, C.-M.; Xue, Desheng

    2016-10-01

    The anomalous Hall effect (AHE) was used to investigate the magnetization dynamics of an ultrathin (1.3 nm) CoFeB magnetic multilayer with perpendicular magnetic anisotropy (PMA). By directly sending a radio frequency (rf) current into a millimeter-sized film sample without any lithography process, a resonant dc voltage can be detected along the Hall direction. This method was used to study the dynamic properties of ultrathin CoFeB films, such as the gyromagnetic ratio, amplitude of PMA field, and magnetic damping. The dc voltage was proven to be the consequence of spin rectification enabled by the AHE, and the dynamic magnetization was driven by the Oersted field and spin current from the electric current in the adjacent Ta layer.

  8. Simulation of dynamic magnetic particle capture and accumulation around a ferromagnetic wire

    Science.gov (United States)

    Choomphon-anomakhun, Natthaphon; Ebner, Armin D.; Natenapit, Mayuree; Ritter, James A.

    2017-04-01

    A new approach for modeling high gradient magnetic separation (HGMS)-type systems during the time-dependent capture and accumulation of magnetic particles by a ferromagnetic wire was developed. This new approach assumes the fluid (slurry) viscosity, comprised of water and magnetic particles, is a function of the magnetic particle concentration in the fluid, with imposed maxima on both the particle concentration and fluid viscosity to avoid unrealistic limits. In 2-D, the unsteady-state Navier-Stokes equations for compressible fluid flow and the unsteady-state continuity equations applied separately to the water and magnetic particle phases in the slurry were solved simultaneously, along with the Laplace equations for the magnetic potential applied separately to the slurry and wire, to evaluate the velocities and concentrations around the wire in a narrow channel using COMSOL Multiphysics. The results from this model revealed very realistic magnetically attractive and repulsive zones forming in time around the wire. These collection zones formed their own impermeable viscous phase during accumulation that was also magnetic with its area and magnetism impacting locally both the fluid flow and magnetic fields around the wire. These collection zones increased with an increase in the applied magnetic field. For a given set of conditions, the capture ability peaked and then decreased to zero at infinite time during magnetic particle accumulation in the collection zones. Predictions of the collection efficiency from a steady-state, clean collector, trajectory model could not show this behavior; it also agreed only qualitatively with the dynamic model and then only at the early stages of collection and more so at a higher applied magnetic field. Also, the collection zones decreased in size when the accumulation regions included magnetic particle magnetization (realistic) compared to when they excluded it (unrealistic). Overall, this might be the first time a mathematical

  9. Dynamic magnetic resonance defecography in 10 asymptomatic volunteers

    Institute of Scientific and Technical Information of China (English)

    Andreas G Schreyer; Christian Paetzel; Alois Fürst; Lena M Dendl; Elisabeth Hutzel; René Müller-Wille; Philipp Wiggermann

    2012-01-01

    AIM:Evaluation of the wide range of normal findings in asymptomatic women undergoing dynamic magnetic resonance (MR) defecography.METHODS:MR defecography of 10 healthy female volunteers (median age:31 years) without previous pregnancies or history of surgery were evaluated.The rectum was filled with 180 mL gadolinium ultrasound gel mixture.MR defecography was performed in the supine position.The pelvic floor was visualized with a dynamic T2-weighted sagittal plane where all relevant pelvic floor organs were acquired during defecation.The volunteers were instructed to relax and then to perform straining maneuvers to empty the rectum.The pubococcygeal line (PCGL) was used as the line of reference.The movement of pelvic floor organs was measured as the vertical distance to this reference line.Data were recorded in the resting position as well as during the defecation process with maximal straining.Examinations were performed and evaluated by two experienced abdominal radiologists without knowledge of patient history.RESULTS:Average position of the anorectal junction was located at-5.3 mm at rest and-29.9 mm during straining.The anorectal angle widened significantly from 93° at rest to 109° during defecation.A rectocele was diagnosed in eight out of 10 volunteers showing an average diameter of 25.9 mm.The bladder base was located at a position of +23 mm at rest and descended to-8.1 mm during defecation in relation to the PCGL.The bladder base moved below the PCGL in six out of 10 volunteers,which was formally defined as a cystocele.The uterocervical junction was located at an average level of +43.1 mm at rest and at +7.9 mm during straining.The uterocervical junction of three volunteers fell below the PCGL; described formally as uterocervical prolapse.CONCLUSION:Based on the range of standard values in asymptomatic volunteers,MR defecography values for pathological changes have to be re-evaluated.

  10. Chaotic dynamics and basin erosion in nanomagnets subject to time-harmonic magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M., E-mail: daquino@uniparthenope.it [Engineering Department, University of Naples “Parthenope”, 80143 Naples (Italy); Quercia, A.; Serpico, C. [DIETI, University of Naples Federico II, 80125 Naples (Italy); Bertotti, G. [Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD 20742 (United States); Perna, S. [DIETI, University of Naples Federico II, 80125 Naples (Italy); Ansalone, P. [Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy)

    2016-04-01

    Magnetization dynamics in uniformly magnetized particles subject to time-harmonic (AC) external fields is considered. The study is focused on the behavior of the AC-driven dynamics close to saddle equilibria. It happens that such dynamics has chaotic nature at moderately low power level, due to the heteroclinic tangle phenomenon which is produced by the combined effect of AC-excitations and saddle type dynamics. By using analytical theory for the threshold AC excitation amplitudes necessary to create the heteroclinic tangle together with numerical simulations, we quantify and show how the tangle produces the erosion of the safe basin around the stable equilibria.

  11. Influence of dynamic crystallization on exchange-coupled NdFeB nanocrystalline permanent magnets

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ran; LIU Ying; MA Yilong; ZHANG Longfeng; XU Jianchuan; GAO Shengji

    2006-01-01

    Dynamic crystallization was introduced to improve the magnetic properties of NdFeB nanocrystalline permanent magnets by optimizing microstructure. The microstructure was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It has been determined that, compared with the conventional heat treatment, dynamic crystallization can shorten the crystallization time. Moreover, dynamic crystallization can refine grains, enhance the exchange-coupled interaction among grains, and promote the magnetic properties. As a result, the optimal magnetic properties of Nd10.5(FeCoZr)83.4B6.1(Br=0.685T, Hci =732 kA·m -1 , Hcb =429 kA·m-1 ,( BH )m=75 kJ·m -3 ) are obtained after dynamic crystallization heat treatment at 700 ℃ for 10 min.

  12. Comparing localized and nonlocalized dynamic (31) P magnetic resonance spectroscopy in exercising muscle at 7T

    NARCIS (Netherlands)

    Meyerspeer, M.; Robinson, S.; Nabuurs, C.I.H.C.; Scheenen, T.W.; Schoisengeier, A.; Unger, E.; Kemp, G.J.; Moser, E.

    2012-01-01

    By improving spatial and anatomical specificity, localized spectroscopy can enhance the power and accuracy of the quantitative analysis of cellular metabolism and bioenergetics. Localized and nonlocalized dynamic (31) P magnetic resonance spectroscopy using a surface coil was compared during aerobic

  13. Comparing localized and nonlocalized dynamic (31) P magnetic resonance spectroscopy in exercising muscle at 7T

    NARCIS (Netherlands)

    Meyerspeer, M.; Robinson, S.; Nabuurs, C.I.H.C.; Scheenen, T.W.; Schoisengeier, A.; Unger, E.; Kemp, G.J.; Moser, E.

    2012-01-01

    By improving spatial and anatomical specificity, localized spectroscopy can enhance the power and accuracy of the quantitative analysis of cellular metabolism and bioenergetics. Localized and nonlocalized dynamic (31) P magnetic resonance spectroscopy using a surface coil was compared during aerobic

  14. Dynamic nuclear magnetic resonance field sensing with part-per-trillion resolution

    Science.gov (United States)

    Gross, Simon; Barmet, Christoph; Dietrich, Benjamin E.; Brunner, David O.; Schmid, Thomas; Pruessmann, Klaas P.

    2016-12-01

    High-field magnets of up to tens of teslas in strength advance applications in physics, chemistry and the life sciences. However, progress in generating such high fields has not been matched by corresponding advances in magnetic field measurement. Based mostly on nuclear magnetic resonance, dynamic high-field magnetometry is currently limited to resolutions in the nanotesla range. Here we report a concerted approach involving tailored materials, magnetostatics and detection electronics to enhance the resolution of nuclear magnetic resonance sensing by three orders of magnitude. The relative sensitivity thus achieved amounts to 1 part per trillion (10-12). To exemplify this capability we demonstrate the direct detection and relaxometry of nuclear polarization and real-time recording of dynamic susceptibility effects related to human heart function. Enhanced high-field magnetometry will generally permit a fresh look at magnetic phenomena that scale with field strength. It also promises to facilitate the development and operation of high-field magnets.

  15. Magnetization dynamics in (Cd,Mn)Te quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Goryca, M.; Nawrocki, M. [Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw (Poland); Ferrand, D.; Tatarenko, S. [Joined group ' ' Nanophysique et semiconducteurs' ' , CNRS/CEA/Universite Joseph Fourier-Grenoble, Laboratoire de Spectrometrie Physique, BP 87, 38402 Saint Martin d' Heres cedex (France); Kossacki, P.; Pacuski, W.; Maslana, W. [Institute of Experimental Physics, Warsaw University, Hoza 69, 00-681 Warsaw (Poland); Joined group ' ' Nanophysique et semiconducteurs' ' , CNRS/CEA/Universite Joseph Fourier-Grenoble, Laboratoire de Spectrometrie Physique, BP 87, 38402 Saint Martin d' Heres cedex (France); Cibert, J. [Laboratoire Louis Neel, CNRS, BP166, 38042 Grenoble cedex 9 (France)

    2006-03-15

    The relaxation of the magnetization change induced by a short pulse of magnetic field in p-doped (Cd,Mn)Te quantum wells is determined from the giant Zeeman shift of the photoluminescence line. The characteristic times change by three orders of magnitude upon application of a static magnetic field. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. DEVELOPMENT OF EMBEDDED SYSTEM FOR REMOTE MEASURING OF DYNAMIC MAGNETIC FIELDS USING ZIGBEE

    OpenAIRE

    Thiago Dantas da Silva; Jacques Cousteau da Silva Borges; Allan Aminadab André Freire Soares

    2016-01-01

    This paper aims to describe the development and implementation of an embedded system applied to remote measurement of dynamic artificial magnetic fields using Zigbee, which is a set of specifications for wireless data communication (based on IEEE standard 802.15.4). In the implementation of this system, Arduino microcontrolled platforms were used integrated to a Hall effect sensor intended for measuring the strength of these dynamic magnetic fields. The Zigbee technology aims to enable the ex...

  17. Biosensor based on the measurements of clustering dynamics of magnetic particles using a double pass setup

    DEFF Research Database (Denmark)

    2014-01-01

    Disclosed herein is a biosensor for optical detection of Brownian relaxation dynamics of magnetic particles measured by light transmission. The magnetic particles can be functionalized with biological ligands for the detection of target analytes in a sample. The setup may be implemented in a disc...

  18. A computer-aided diagnosis system for breast DCE-MRI at high spatiotemporal resolution

    NARCIS (Netherlands)

    Dalmis, M.U.; Gubern-Merida, A.; Vreemann, S.; Karssemeijer, N.; Mann, R.; Platel, B.

    2016-01-01

    PURPOSE: With novel MRI sequences, high spatiotemporal resolution has become available in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of the breast. Since benign structures in the breast can show enhancement similar to malignancies in DCE-MRI, characterization of detected lesions

  19. Nonlinear dynamic behaviour of a rotor-foundation system coupled through passive magnetic bearings with magnetic anisotropy - Theory and experiment

    DEFF Research Database (Denmark)

    Enemark, Søren; Santos, Ilmar F.

    2016-01-01

    In this work, the nonlinear dynamic behaviour of a vertical rigid rotor interacting with a flexible foundation by means of two passive magnetic bearings is quantified and evaluated. The quantification is based on theoretical and experimental investigation of the non-uniformity (anisotropy) of the...

  20. Dynamic magnetic resonance angiography for localization of hyperfunctioning parathyroid glands in the reoperative neck

    Energy Technology Data Exchange (ETDEWEB)

    Aschenbach, R., E-mail: rene.aschenbach@helios-kliniken.de [HELIOS Hospital Erfurt, Department of Diagnostic and Interventional Radiology and Neuroradiology, Nordhaeuser Str. 74, 99089 Erfurt (Germany); Tuda, S. [HELIOS Hospital Erfurt, Department of Diagnostic and Interventional Radiology and Neuroradiology, Nordhaeuser Str. 74, 99089 Erfurt (Germany); Lamster, E.; Meyer, A. [HELIOS Hospital Erfurt, Department of Endocrinology, Nordhaeuser Str. 74, 99089 Erfurt (Germany); Roediger, H.; Stier, A. [HELIOS Hospital Erfurt, Department of Visceral Surgery, Nordhaeuser Str. 74, 99089 Erfurt (Germany); Conrad, E. [HELIOS Hospital Erfurt, Department of Nuclear Medicine, Nordhaeuser Str. 74, 99089 Erfurt (Germany); Basche, S.; Klisch, J. [HELIOS Hospital Erfurt, Department of Diagnostic and Interventional Radiology and Neuroradiology, Nordhaeuser Str. 74, 99089 Erfurt (Germany); Vogl, T.J. [University Hospital Frankfurt/Main, Center of Diagnostic and Interventional Radiology, Theodor-Stern-Kai 7, 60590 Frankfurt/Main (Germany)

    2012-11-15

    Objectives: To evaluate the use of dynamic magnetic resonance angiography for localization of hyperfunctioning parathyroid glands in the reoperative neck. Methods: We retrospectively evaluated the head-neck MRIs of 30 patients with a history of hyperparathyroidism, prior head-neck surgery, and intraoperative proven adenomas. The protocol included conventional imaging with T2-weighted STIR sequences, T1w axial and coronal prior to and after contrast media administration, and dynamic magnetic resonance angiography. We compared the results from MRI, dynamic magnetic resonance angiography with 99m-Tc-Sestamibi with intraoperative findings as the gold standard. Results: In conventional MRI 19/30 true positives were detected with a sensitivity and specificity of 63.3% and 100%, respectively. However, by adding dynamic magnetic resonance angiography the detection rate increased to 28/30 true positives. Based on intraoperative findings, the sensitivity and specificity of dynamic magnetic resonance angiography were 93.3% and 100%, respectively. 99m-Tc-Sestamibi detected 24/30 true positives, sensitivity was 80%. Conclusion: The diagnostic value of MRI including dynamic magnetic resonance angiography is superior to MRI alone and superior to that of 99m-Tc-Sestamibi in the diagnostic workup of hyperfunctioning parathyroid glands when compared against intraoperative findings.

  1. Estimating the contribution of Brownian and Néel relaxation in a magnetic fluid through dynamic magnetic susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado-Camargo, L. [Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 (United States); Torres-Díaz, I. [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States); Chiu-Lam, A. [Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 (United States); Hernández, M. [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States); Rinaldi, C., E-mail: carlos.rinaldi@bme.ufl.edu [Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 (United States); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2016-08-15

    We demonstrate how dynamic magnetic susceptibility measurements (DMS) can be used to estimate the relative contributions of Brownian and Néel relaxation to the dynamic magnetic response of a magnetic fluid, a suspension of magnetic nanoparticles. The method applies to suspensions with particles that respond through Brownian or Néel relaxation and for which the characteristic Brownian and Néel relaxation times are widely separated. First, we illustrate this using magnetic fluids consisting of mixtures of particles that relax solely by the Brownian or Néel mechanisms. Then, it is shown how the same approach can be applied to estimate the relative contributions of Brownian and Néel relaxation in a suspension consisting of particles obtained from a single synthesis and whose size distribution straddles the transition from Néel to Brownian relaxation. - Highlights: • Method to estimate the contributions of the relaxation mechanism to the magnetic response. • Method applies to cases where the Brownian and Néel peaks do not overlap. • The method applies for ferrofluids prepared with as–synthesized particles.

  2. Magnetic lattice dynamics of the oxygen-free FeAs pnictides: how sensitive are phonons to magnetic ordering?

    Science.gov (United States)

    Zbiri, Mohamed; Mittal, Ranjan; Rols, Stéphane; Su, Yixi; Xiao, Yinguo; Schober, Helmut; Chaplot, Samrath L; Johnson, Mark R; Chatterji, Tapan; Inoue, Yasunori; Matsuishi, Satoru; Hosono, Hideo; Brueckel, Thomas

    2010-08-11

    To shed light on the role of magnetism on the superconducting mechanism of the oxygen-free FeAs pnictides, we investigate the effect of magnetic ordering on phonon dynamics in the low-temperature orthorhombic parent compounds, which present a spin density wave. The study covers both the 122 (AFe(2)As(2); A = Ca, Sr, Ba) and 1111 (AFeAsF; A = Ca, Sr) phases. We extend our recent work on the Ca (122 and 1111) and Ba (122) cases by treating, computationally and experimentally, the 122 and 1111 Sr compounds. The effect of magnetic ordering is investigated through detailed non-magnetic and magnetic lattice dynamical calculations. The comparison of the experimental and calculated phonon spectra shows that the magnetic interactions/ordering have to be included in order to reproduce well the measured density of states. This highlights a spin-correlated phonon behavior which is more pronounced than the apparently weak electron-phonon coupling estimated in these materials. Furthermore, there is no noticeable difference between phonon spectra of the 122 Ba and Sr, whereas there are substantial differences when comparing these to CaFe(2)As(2) originating from different aspects of structure and bonding.

  3. Statistical comparison of dynamic contrast-enhanced MRI pharmacokinetic models in human breast cancer.

    Science.gov (United States)

    Li, Xia; Welch, E Brian; Chakravarthy, A Bapsi; Xu, Lei; Arlinghaus, Lori R; Farley, Jaime; Mayer, Ingrid A; Kelley, Mark C; Meszoely, Ingrid M; Means-Powell, Julie; Abramson, Vandana G; Grau, Ana M; Gore, John C; Yankeelov, Thomas E

    2012-07-01

    By fitting dynamic contrast-enhanced MRI data to an appropriate pharmacokinetic model, quantitative physiological parameters can be estimated. In this study, we compare four different models by applying four statistical measures to assess their ability to describe dynamic contrast-enhanced MRI data obtained in 28 human breast cancer patient sets: the chi-square test (χ(2)), Durbin-Watson statistic, Akaike information criterion, and Bayesian information criterion. The pharmacokinetic models include the fast exchange limit model with (FXL_v(p)) and without (FXL) a plasma component, and the fast and slow exchange regime models (FXR and SXR, respectively). The results show that the FXL_v(p) and FXR models yielded the smallest χ(2) in 45.64 and 47.53% of the voxels, respectively; they also had the smallest number of voxels showing serial correlation with 0.71 and 2.33%, respectively. The Akaike information criterion indicated that the FXL_v(p) and FXR models were preferred in 42.84 and 46.59% of the voxels, respectively. The Bayesian information criterion also indicated the FXL_v(p) and FXR models were preferred in 39.39 and 45.25% of the voxels, respectively. Thus, these four metrics indicate that the FXL_v(p) and the FXR models provide the most complete statistical description of dynamic contrast-enhanced MRI time courses for the patients selected in this study.

  4. Dynamic relaxation in algebraic reconstruction technique (ART) for breast tomosynthesis imaging.

    Science.gov (United States)

    Oliveira, N; Mota, A M; Matela, N; Janeiro, L; Almeida, P

    2016-08-01

    A major challenge in Digital Breast Tomosynthesis (DBT) is handling image noise since the 3D reconstructed images are obtained from low dose projections and limited angular range. The use of the iterative reconstruction algorithm Algebraic Reconstruction Technique (ART) in clinical context depends on two key factors: the number of iterations needed (time consuming) and the image noise after iterations. Both factors depend highly on a relaxation coefficient (λ), which may give rise to slow or noisy reconstructions, when a single λ value is considered for the entire iterative process. The aim of this work is to present a new implementation for the ART that takes into account a dynamic mode to calculate λ in DBT image reconstruction. A set of initial reconstructions of real phantom data was done using constant λ values. The results were used to choose, for each iteration, the suitable λ value, taking into account the image noise level and the convergence speed. A methodology to optimize λ automatically during the image reconstruction was proposed. Results showed we can dynamically choose λ values in such a way that the time needed to reconstruct the images can be significantly reduced (up to 70%) while achieving similar image quality. These results were confirmed with one clinical dataset. With simple methodology we were able to dynamically choose λ in DBT image reconstruction with ART, allowing a shorter image reconstruction time without increasing image noise. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. Non-Equilibrium Chemistry of Dynamically Evolving Prestellar Cores: I. Basic Magnetic and Non-Magnetic Models and Parameter Studies

    CERN Document Server

    Tassis, Konstantinos; Yorke, Harold W; Turner, Neal

    2011-01-01

    We combine dynamical and non-equilibrium chemical modeling of evolving prestellar molecular cloud cores, and explore the evolution of molecular abundances in the contracting core. We model both magnetic cores, with varying degrees of initial magnetic support, and non-magnetic cores, with varying collapse delay times. We explore, through a parameter study, the competing effects of various model parameters in the evolving molecular abundances, including the elemental C/O ratio, the temperature, and the cosmic-ray ionization rate. We find that different models show their largest quantitative differences at the center of the core, whereas the outer layers, which evolve slower, have abundances which are severely degenerate among different dynamical models. There is a large range of possible abundance values for different models at a fixed evolutionary stage (central density), which demonstrates the large potential of chemical differentiation in prestellar cores. However, degeneracies among different models, compou...

  6. Assessment of magnetic resonance imaging of the breast using 0.5 T equipment; Valoracion de la resonancia magnetic de mama en un equipo de 0.5 T

    Energy Technology Data Exchange (ETDEWEB)

    Vilanova, J. C.; Barcelo, J.; Ferrer, J.; Castaner, F.; Miro, J.; Bassaganyas, R.; Viejo, N.; Albanell, J.; Villalon, M.

    2002-07-01

    To evaluate the efficacy of a magnetic resonance imaging technique of the breast using half-field equipment (0.5 T). We evaluated 191 magnetic resonance (MRI) studies made at our center from March 1998 to March 2001 using Signa Contour 0.5 T MRI equipment of General Electric. A dedicated bilateral breast made at fat saturation in the coronal plane before administering intravenous gadolinium, then 6 consecutive times after contrast administration. The sequence acquisition time was 70-90 seconds Image post processing included subtraction and analysis of the intensity/time curves in the region of interest (ROI) together with morphological evaluation of the lesion. Additional T2 weighted fast-spin-echo sequences (FSE T2), T1-weighted spin-echo (SE T1), FSE T2 with fat suppression, and STIR with water saturation were made for studies of breast implants. The clinical indications for MRI study of the breast were masses (n=79), microcalcifications (n=7), asymmetry (n=17), cases of indeterminate risk (n=7), postoperative control (n=51), and breast implants (n=25). The histological diagnosis was benign in 31 lesions and malignant in 73 lesions. The sensitivity specificity, and reliability of breast MRI were 93%, 81% and 89% respectively. Multicenter/multifocal neoplasms were found in 8% of patients and bilateral neoplasms in 2%. The therapeutic attitude was modified in 18% of the patients with breast cancer as a result of MRI findings. The results confirm the usefulness of MRI in the management of patients with breast cancer. Likewise, the present study demonstrated that breast MRI can be carried out with half-field equipment with the same reliability as with full-field equipment as long as specific breast cots are used rapid 3D sequences, and image processing with suitable software. (Author) 28 refs.

  7. Multiple dynamic transitions in an anisotropic Heisenberg ferromagnet driven by polarized magnetic field.

    Science.gov (United States)

    Acharyya, Muktish

    2004-02-01

    A uniaxially (along the Z axis) anisotropic Heisenberg ferromagnet, in the presence of time-dependent (but uniform over space) magnetic field, is studied by Monte Carlo simulation. The time-dependent magnetic field was taken as elliptically polarized where the resultant field vector rotates in the X-Z plane. The system is cooled (in the presence of the elliptically polarized magnetic field) from high temperature. As the temperature decreases, it was found that in the low anisotropy limit the system undergoes three successive dynamical phase transitions. These three dynamic transitions were confirmed by studying the temperature variation of dynamic "specific heat." The temperature variation of dynamic specific heat shows three peaks indicating three dynamic transition points.

  8. Neural network vector quantization improves the diagnostic quality of computer-aided diagnosis in dynamic breast MRI

    Science.gov (United States)

    Wismüller, Axel; Meyer-Baese, Anke; Leinsinger, Gerda L.; Lange, Oliver; Schlossbauer, Thomas; Reiser, Maximilian F.

    2007-03-01

    We quantitatively evaluate a novel neural network pattern recognition approach for characterization of diagnostically challenging breast lesions in contrast-enhanced dynamic breast MRI. Eighty-two women with 84 indeterminate mammographic lesions (BIRADS III-IV, 38/46 benign/malignant lesions confirmed by histopathology and follow-up, median lesion diameter 12mm) were examined by dynamic contrast-enhanced breast MRI. The temporal signal dynamics results in an intensity time-series for each voxel represented by a 6-dimensional feature vector. These vectors were clustered by minimal-free-energy Vector Quantization (VQ), which identifies groups of pixels with similar enhancement kinetics as prototypical time-series, so-called codebook vectors. For comparison, conventional analysis based on lesion-specific averaged signal-intensity time-courses was performed according to a standardized semi-quantitative evaluation score. For quantitative assessment of diagnostic accuracy, areas under ROC curves (AUC) were computed for both VQ and standard classification methods. VQ increased the diagnostic accuracy for classification between benign and malignant lesions, as confirmed by quantitative ROC analysis: VQ results (AUC=0.760) clearly outperformed the conventional evaluation of lesion-specific averaged time-series (AUC=0.693). Thus, the diagnostic benefit of neural network VQ for MR mammography analysis is quantitatively documented by ROC evaluation in a large data base of diagnostically challenging small focal breast lesions. VQ outperforms the conventional method w.r.t. diagnostic accuracy.

  9. Dynamic modeling of breast tissue with application of model reference adaptive system identification technique based on clinical robot-assisted palpation.

    Science.gov (United States)

    Keshavarz, M; Mojra, A

    2015-11-01

    Accurate identification of breast tissue's dynamic behavior in physical examination is critical to successful diagnosis and treatment. In this study a model reference adaptive system identification (MRAS) algorithm is utilized to estimate the dynamic behavior of breast tissue from mechanical stress-strain datasets. A robot-assisted device (Robo-Tac-BMI) is going to mimic physical palpation on a 45 year old woman having a benign mass in the left breast. Stress-strain datasets will be collected over 14 regions of both breasts in a specific period of time. Then, a 2nd order linear model is adapted to the experimental datasets. It was confirmed that a unique dynamic model with maximum error about 0.89% is descriptive of the breast tissue behavior meanwhile mass detection may be achieved by 56.1% difference from the normal tissue.

  10. First-principles approach to noncollinear magnetism: Towards spin dynamics

    DEFF Research Database (Denmark)

    Sharma, S.; Dewhurst, J.K.; Ambrosch-Draxl, C.;

    2007-01-01

    A description of noncollinear magnetism in the framework of spin-density functional theory is presented for the exact exchange energy functional which depends explicitly on two-component spinor orbitals. The equations for the effective Kohn-Sham scalar potential and magnetic field are derived...

  11. Orbital Magnetism and Dynamics in Alkali Metal Clusters

    CERN Document Server

    Nesterenko, V O; De Souza-Cruz, F F; Marinelli, J R

    2000-01-01

    Two remarkable orbital magnetic resonances, M1 scissor mode and M2 twist mode, are predicted in deformed and spherical metal clusters, respectively. We show that these resonances provide a valuable information about many cluster properties (quadrupole deformation, magnetic susceptibility, single-particle spectrum, etc.)

  12. Transient Grating Spectroscopy in Magnetic Thin Films : Simultaneous Detection of Elastic and Magnetic Dynamics

    NARCIS (Netherlands)

    Janusonis, J.; Jansma, T.; Chang, C. L.; Liu, Qi; Gatilova, A.; Lomonosov, A. M.; Shalagatskyi, V.; Pezeril, T.; Temnov, V. V.; Tobey, R. I.

    2016-01-01

    Surface magnetoelastic waves are coupled elastic and magnetic excitations that propagate along the surface of a magnetic material. Ultrafast optical techniques allow for a non-contact excitation and detection scheme while providing the ability to measure both elastic and magnetic components individu

  13. Dzyaloshinskii-Moriya interactions and adiabatic magnetization dynamics in molecular magnets

    NARCIS (Netherlands)

    De Raedt, H; Miyashita, S; Michielsen, K; Machida, M

    A microscopic model of the molecular magnet V-15 is used to study mechanisms for the adiabatic change of the magnetization in time-dependent magnetic fields. The effects of the Dzyaloshinskii-Moriya interaction, the most plausible source for the energy-level repulsions that lead to adiabatic changes

  14. Liquid Droplet Dynamics in Gravity Compensating High Magnetic Field

    Science.gov (United States)

    Bojarevics, V.; Easter, S.; Pericleous, K.

    2012-01-01

    Numerical models are used to investigate behavior of liquid droplets suspended in high DC magnetic fields of various configurations providing microgravity-like conditions. Using a DC field it is possible to create conditions with laminar viscosity and heat transfer to measure viscosity, surface tension, electrical and thermal conductivities, and heat capacity of a liquid sample. The oscillations in a high DC magnetic field are quite different for an electrically conducting droplet, like liquid silicon or metal. The droplet behavior in a high magnetic field is the subject of investigation in this paper. At the high values of magnetic field some oscillation modes are damped quickly, while others are modified with a considerable shift of the oscillating droplet frequencies and the damping constants from the non-magnetic case.

  15. Dynamics of magnetic nano-flake vortices in Newtonian fluids

    Science.gov (United States)

    Bazazzadeh, Nasim; Mohseni, Seyed Majid; Khavasi, Amin; Zibaii, Mohammad Ismail; Movahed, S. M. S.; Jafari, G. R.

    2016-12-01

    We study the rotational motion of nano-flake ferromagnetic disks suspended in a Newtonian fluid, as a potential material owing the vortex-like magnetic configuration. Using analytical expressions for hydrodynamic, magnetic and Brownian torques, the stochastic angular momentum equation is determined in the dilute limit conditions under applied magnetic field. Results are compared against experimental ones and excellent agreement is observed. We also estimate the uncertainty in the orientation of the disks due to the Brownian torque when an external magnetic field aligns them. Interestingly, this uncertainty is roughly proportional to the ratio of thermal energy of fluid to the magnetic energy stored in the disks. Our approach can be implemented in many practical applications including biotechnology and multi-functional fluidics.

  16. In vivo determination of human breast fat composition by ¹H magnetic resonance spectroscopy at 7 T.

    Science.gov (United States)

    Dimitrov, Ivan E; Douglas, Deborah; Ren, Jimin; Smith, Nadine B; Webb, Andrew G; Sherry, A Dean; Malloy, Craig R

    2012-01-01

    The role of diet and fat consumption in the pathogenesis of breast cancer is an important subject. We report a method for noninvasive determination of lipid composition in human breast by proton magnetic resonance spectroscopy (MRS) at 7 T. Two respiratory-triggered TE-averaged stimulated echo acquisition mode (STEAM) acquisitions were performed on the adipose tissue of 10 healthy volunteers where the second acquisition had all gradients inverted. This acquisition protocol allows the suppression of modulation sidebands that complicate spectral analysis at the short TE(avg) = 24.5 ms. The entire acquisition takes ∼10 min. Ten lipid peaks were typically resolved. T(1) and T(2) were also measured and used to correct the peak intensities. The calculated average lipid composition for saturated was 28.7 ± 8.4%, monounsaturated, 48.5 ± 7.9%, and polyunsaturated, 22.7 ± 3.1%, in close agreement with reported values from subcutaneous adipose measurements. Intrasubject variability was 2.0, 1.6, and 3.6% for the saturated, monounsaturated, and polyunsaturated fractions, respectively. In conclusion, we have shown that a chemical analysis of lipids in breast tissue can be determined quite simply, quickly, and noninvasively by proton MRS at 7 T.

  17. Breast cancer cell targeted MR molecular imaging probe: Anti-MUC1 antibody-based magnetic nanoparticles

    Science.gov (United States)

    Moradi Khaniabadi, P.; S. A Majid, A. M.; Asif, M.; Moradi Khaniabadi, B.; Shahbazi-Gahrouei, D.; Jaafar, M. S.

    2017-05-01

    Effective and specific diagnostic imaging techniques are important in early-stage breast cancer treatment. The objective of this study was to develop a specific breast cancer contrast agent for magnetic resonance imaging (MRI). In so doing, superparamagnetic iron oxide nanoparticles (SPIONs) were conjugated to C595 monoclonal antibody using EDC chemistry to produce nanoprobe with high relaxivity and narrow size (87.4±0.7 nm). To test the developed nanoprobe in vitro, assessments including Cell toxicity, targeting efficacy, cellular binding, and MR imaging were carried out. The results indicated that after 6 hrs incubation with MCF-7 cells at 200 to 25 µg Fe/ml doses, 76% to 16% T2 reduction was obtained. The presence of iron localised in MCF-7 cells measured by atomic absorption spectroscopy (AAS) was about 9.95±0.09 ppm iron/cell at higher doses of nanoprobe. Moreover, a linear relationship between iron concentration of nontoxic SPION-C595 and T2 relaxation times was observed. This study also revealed that developed nanoprobe might be used as a specific negative contrast agent for detecting breast cancer.

  18. Molecular dynamics simulations of proton transverse relaxation times in suspensions of magnetic nanoparticles.

    Science.gov (United States)

    Panczyk, Tomasz; Konczak, Lukasz; Zapotoczny, Szczepan; Szabelski, Pawel; Nowakowska, Maria

    2015-01-01

    In this work we have analyzed the influence of various factors on the transverse relaxation times T2 of water protons in suspension of magnetic nanoparticles. For that purpose we developed a full molecular dynamics force field which includes the effects of dispersion interactions between magnetic nanoparticles and water molecules, electrostatic interactions between charged nanoparticles and magnetic dipole-dipole and dipole-external field interactions. We also accounted for the magnetization reversal within the nanoparticles body frames due to finite magnetic anisotropy barriers. The force field together with the Langevin dynamics imposed on water molecules and the nanoparticles allowed us to monitor the dephasing of water protons in real time. Thus, we were able to determine the T2 relaxation times including the effects of the adsorption of water on the nanoparticles' surfaces, thermal fluctuations of the orientation of nanoparticles' magnetizations as well as the effects of the core-shell architecture of nanoparticles and their agglomeration into clusters. We found that there exists an optimal cluster size for which T2 is minimized and that the retardation of water molecules motion, due to adsorption on the nanoparticles surfaces, has some effect in the measured T2 times. The typical strengths of the external magnetic fields in MRI are enough to keep the magnetizations fixed along the field direction, however, in the case of low magnetic fields, we observed significant enhancement of T2 due to thermal fluctuations of the orientations of magnetizations. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Breast cancer screening in Korean woman with dense breast tissue

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hee Jung [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Ko, Eun Sook [Dept. of Radiology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul (Korea, Republic of); Yi, Ann [Dept. of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul (Korea, Republic of)

    2015-11-15

    Asian women, including Korean, have a relatively higher incidence of dense breast tissue, compared with western women. Dense breast tissue has a lower sensitivity for the detection of breast cancer and a higher relative risk for breast cancer, compared with fatty breast tissue. Thus, there were limitations in the mammographic screening for women with dense breast tissue, and many studies for the supplemental screening methods. This review included appropriate screening methods for Korean women with dense breasts. We also reviewed the application and limitation of supplemental screening methods, including breast ultrasound, digital breast tomosynthesis, and breast magnetic resonance imaging; and furthermore investigated the guidelines, as well as the study results.

  20. Compact sensor for measuring nonlinear rotational dynamics of driven magnetic microspheres with biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    McNaughton, Brandon H. [Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Applied Physics Program, University of Michigan, Ann Arbor, MI 48109-1040 (United States)], E-mail: bmcnaugh@umich.edu; Kinnunen, Paivo [Applied Physics Program, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Smith, Ron G.; Pei, S.N. [Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Torres-Isea, Ramon [Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Kopelman, Raoul [Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Applied Physics Program, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055 (United States); Clarke, Roy [Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040 (United States); Applied Physics Program, University of Michigan, Ann Arbor, MI 48109-1040 (United States)

    2009-05-15

    The nonlinear rotation response of a magnetic particle occurs when a driving magnetic field, used to rotate the magnetic particle, exceeds a critical frequency. This type of nonlinear rotational dynamic depends on several physical parameters, such as the rotational drag that the particle experiences. Shifts in this nonlinear rotational frequency offer a dynamic approach for the detection of bacteria, measurement of their growth, their response to chemical agents, and other biomedical applications. Therefore, we have developed a stand-alone prototype device that utilizes an elegant combination of a laser diode and photodiode to monitor particle rotation.

  1. DEVELOPMENT OF EMBEDDED SYSTEM FOR REMOTE MEASURING OF DYNAMIC MAGNETIC FIELDS USING ZIGBEE

    Directory of Open Access Journals (Sweden)

    Thiago Dantas da Silva

    2016-04-01

    Full Text Available This paper aims to describe the development and implementation of an embedded system applied to remote measurement of dynamic artificial magnetic fields using Zigbee, which is a set of specifications for wireless data communication (based on IEEE standard 802.15.4. In the implementation of this system, Arduino microcontrolled platforms were used integrated to a Hall effect sensor intended for measuring the strength of these dynamic magnetic fields. The Zigbee technology aims to enable the execution of real-time and in remote character of these measurements of magnetic field intensity, presenting them in a graphical view.

  2. Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

    Science.gov (United States)

    Kodama, Kazuto

    2015-02-01

    This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder) as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM). These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization-field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization) at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

  3. Scintimammography with 99mTc-MIBI and magnetic resonance imaging in the evaluation of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Bagni, B.; Franceschetto, A.; Casolo, A. [Department of Nuclear Medicine, University Hospital, University of Modena and Reggio Emilia, Via del Pozzo 71, 41100, Modena (Italy); De Santis, M. [Department of Radiology, University Hospital, University of Modena and Reggio Emilia, Modena (Italy); Bagni, I. [Department of Pathology, University of Ferrara, Ferrara (Italy); Pansini, F. [OBJ Department, University of Ferrara, Ferrara (Italy); Di Leo, C. [Department of Nuclear Medicine, University Hospital of San Paolo, University of Milan, Milan (Italy)

    2003-10-01

    This study was performed to evaluate the sensitivity and specificity of technetium-99m methoxyisobutylisonitrile ({sup 99m}Tc-MIBI) scintimammography (SMM) and contrast-enhanced magnetic resonance imaging (MRI) in patients with breast masses, using the histological findings as the gold standard. Forty-five consecutive patients with a breast lesion, detected by self-examination, physical examination or screening mammography, underwent SMM and MRI. In 38 cases (84.5%), the histopathology was malignant; the breast cancers ranged from 3 to 100 mm in diameter (mean 22 mm). In the overall patient group, MRI showed a slightly higher sensitivity than SMM (92% vs 84%), but SMM showed a better specificity: 71% vs 42%. The accuracy was 82% and 84% for SMM and MRI respectively. To evaluate the influence of lesion size on the results, patients with lesions {<=}20 mm and {<=}15 mm were examined. In patients with lesions {<=}20 mm, the sensitivity of SMM and MRI decreased to 64% and 82% respectively, while SMM again displayed considerably better specificity: 83% vs 50% for MRI. The accuracy of SMM and MRI was 64% and 82% respectively. In patients with lesions {<=}15 mm, SMM again showed better specificity (75% vs 50%), while MRI displayed better sensitivity and accuracy (sensitivity, 81% vs 62%; accuracy, 75% vs 65%). In this study the specificity of SMM in patients with breast lesions was thus superior to that of MRI. The combination of SMM and MRI may be used in those patients with equivocal findings at mammography and ultrasound to reduce the number of unnecessary surgical biopsies. (orig.)

  4. Magnetic Fields are not ignorable in the dynamics of disks

    CERN Document Server

    Battaner, E; Guijarro, A

    2000-01-01

    Magnetic fields are considered to be dominant when $\\epsilon_{B}\\geq\\epsilon_{K}$, being $\\epsilon_{B}=B^{2}/8\\pi$ the magnetic energy density and $\\epsilon_{K}=1/2 \\rho\\theta^{2}$ the rotation energy density, for a conventional moderate B= 1 $\\mu$G. They are considered to be negligible when $\\epsilon_{B}<\\epsilon_{K}$ for $B\\sim 10 \\mu$G. With no assumption and no theoretical calculation, we show that magnetic fields cannot be ignored in the outer parts of a galaxy like the Milky Way and in the whole disk of a dwarf galaxy.

  5. A study on dynamic heat assisted magnetization reversal mechanisms under insufficient reversal field conditions

    Science.gov (United States)

    Chen, Y. J.; Yang, H. Z.; Leong, S. H.; Wu, B. L.; Asbahi, M.; Yu Ko, Hnin Yu; Yang, J. K. W.; Ng, V.

    2014-10-01

    We report an experimental study on the dynamic thermomagnetic (TM) reversal mechanisms at around Curie temperature (Tc) for isolated 60 nm pitch single-domain [Co/Pd] islands heated by a 1.5 μm spot size laser pulse under an applied magnetic reversal field (Hr). Magnetic force microscopy (MFM) observations with high resolution MFM tips clearly showed randomly trapped non-switched islands within the laser irradiated spot after dynamic TM reversal process with insufficient Hr strength. This observation provides direct experimental evidence by MFM of a large magnetization switching variation due to increased thermal fluctuation/agitation over magnetization energy at the elevated temperature of around Tc. The average percentage of non-switched islands/magnetization was further found to be inversely proportional to the applied reversal field Hr for incomplete magnetization reversal when Hr is less than 13% of the island coercivity (Hc), showing an increased switching field distribution (SFD) at elevated temperature of around Tc (where main contributions to SFD broadening are from Tc distribution and stronger thermal fluctuations). Our experimental study and results provide better understanding and insight on practical heat assisted magnetic recording (HAMR) process and recording performance, including HAMR writing magnetization dynamics induced SFD as well as associated DC saturation noise that limits areal density, as were previously observed and investigated by theoretical simulations.

  6. Magnetic suspension motorized spindle-cutting system dynamics analysis and vibration control review

    Directory of Open Access Journals (Sweden)

    Xiaoli QIAO

    2016-10-01

    Full Text Available The performance of high-speed spindle directly determines the development of high-end machine tools. The cutting system's dynamic characteristics and vibration control effect are inseparable with the performance of the spindle,which influence each other, synergistic effect together the cutting efficiency, the surface quality of the workpiece and tool life in machining process. So, the review status on magnetic suspension motorized spindle, magnetic suspension bearing-flexible rotor system dynamics modeling theory and status of active control technology of flexible magnetic suspension motorized spindle rotor vibration are studied, and the problems which present in the magnetic suspension flexible motorized spindle rotor systems are refined, and the development trend of magnetic levitation motorized spindle and the application prospect is forecasted.

  7. Out-of-equilibrium dynamics in superspin glass state of strongly interacting magnetic nanoparticle assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Nakamae, Sawako, E-mail: Sawako.nakamae@cea.fr

    2014-04-15

    Interacting magnetic nanoparticles display a wide variety of magnetic behaviors ranging from modified superparamagnetism, superspin glass to possibly, superferromagnetism. The superspin glass state is described by its slow and out-of-equilibrium magnetic behaviors akin to those found in atomic spin glasses. In this article, recent experimental findings on superspin correlation length growth and the violation of the fluctuation-dissipation theorem obtained in concentrated frozen ferrofluids are presented to illustrate certain out-of-equilibrium dynamics behavior in superspin glasses. - Highlights: • Recent experimental findings on superspin glass dynamics in magnetic nanoparticle systems. • Advantages of magnetic nanoparticles for the study of spin glass physics. • Open questions and future directions in superspin glass research.

  8. Calculating rotating hydrodynamic and magneto-hydrodynamic waves to understand magnetic effects on dynamical tides

    CERN Document Server

    Wei, Xing

    2016-01-01

    For understanding magnetic effects on dynamical tides, we study the rotating magneto-hydrodynamic (MHD) flow driven by harmonic forcing. The linear responses are analytically derived in a periodic box under the local WKB approximation. Both the kinetic and Ohmic dissipations at the resonant frequencies are calculated and the various parameters are investigated. Although magnetic pressure may be negligible compared to thermal pressure, magnetic field can be important for the first-order perturbation, e.g. dynamical tides. It is found that magnetic field splits the resonant frequency, namely the rotating hydrodynamic flow has only one resonant frequency but the rotating MHD flow has two, one positive and the other negative. In the weak field regime the dissipations are asymmetric around the two resonant frequencies and this asymmetry is more striking with a weaker magnetic field. It is also found that both the kinetic and Ohmic dissipations at the resonant frequencies are inversely proportional to the Ekman num...

  9. CFA Films in Amorphous Substrate: Structural Phase Induction and Magnetization Dynamics

    Science.gov (United States)

    Correa, M. A.; Bohn, F.; Escobar, V. M.

    We report a systematic study of the structural and quasi-static magnetic properties, as well as of the dynamic magnetic response through MI effect, in Co2FeAl and MgO//Co2FeAl single layers and a MgO//Co2FeAl/Ag/Co2FeAl trilayered film, all grown onto an amorphous substrate. We present a new route to induce the crystalline structure in the Co2FeAl alloy and verify that changes in the structural phase of this material leads to remarkable modifications of the magnetic anisotropy and, consequently, dynamic magnetic behavior. Considering the electrical and magnetic properties of the Co2FeAl, our results open new possibilities for technological applications of this full-Heusler alloy in rigid and flexible spintronic devices.

  10. On the relationship between G-band bright point dynamics and their magnetic field strengths

    CERN Document Server

    Yang, Yunfei; Ji, Kaifan; Feng, Song; Deng, Hui; Wang, Feng; Lin, Jiaben

    2016-01-01

    G-band bright points (GBPs) are regarded as good manifestations of magnetic flux concentrations. We aim to investigate the relationship between the dynamic properties of GBPs and their longitudinal magnetic field strengths. High spatial and temporal resolution observations were recorded simultaneously with G-band filtergrams and Narrow-band Filter Imager (NFI) Stokes I and V images with Hinode /Solar Optical Telescope. The GBPs are identified and tracked in the G-band images automatically, and the corresponding longitudinal magnetic field strength of each GBP is extracted from the calibrated NFI magnetograms by a point-to-point method. After categorizing the GBPs into five groups by their longitudinal magnetic field strengths, we analyze the dynamics of GBPs of each group. The results suggest that with increasing longitudinal magnetic field strengths of GBPs correspond to a decrease in their horizontal velocities and motion ranges as well as by showing more complicated motion paths. This suggests that magneti...

  11. Dynamical skyrmion state in a spin current nano-oscillator with perpendicular magnetic anisotropy.

    Science.gov (United States)

    Liu, R H; Lim, W L; Urazhdin, S

    2015-04-03

    We study the spectral characteristics of spin current nano-oscillators based on the Pt/[Co/Ni] magnetic multilayer with perpendicular magnetic anisotropy. By varying the applied magnetic field and current, both localized and propagating spin wave modes of the oscillation are achieved. At small fields, we observe an abrupt onset of the modulation sidebands. We use micromagnetic simulations to identify this state as a dynamical magnetic skyrmion stabilized in the active device region by spin current injection, whose current-induced dynamics is accompanied by the gyrotropic motion of the core due to the skew deflection. Our results demonstrate a practical route for controllable skyrmion manipulation by spin current in magnetic thin films.

  12. Magnetization dynamics down to a zero field in dilute (Cd,Mn)Te quantum wells.

    Science.gov (United States)

    Goryca, M; Ferrand, D; Kossacki, P; Nawrocki, M; Pacuski, W; Maślana, W; Gaj, J A; Tatarenko, S; Cibert, J; Wojtowicz, T; Karczewski, G

    2009-01-30

    The evolution of the magnetization in (Cd,Mn)Te quantum wells after a short pulse of magnetic field was determined from the giant Zeeman shift of spectroscopic lines. The dynamics in the absence of a static magnetic field was found to be up to 3 orders of magnitude faster than that at 1 T. Hyperfine interaction and strain are mainly responsible for the fast decay. The influence of a hole gas is clearly visible: at zero field anisotropic holes stabilize the system of Mn ions, while in a magnetic field of 1 T they are known to speed up the decay by opening an additional relaxation channel.

  13. A Laboratory Plasma Experiment for Studying Magnetic Dynamics of Accretion Discs and Jets

    CERN Document Server

    Hsu, S C

    2002-01-01

    This work describes a laboratory plasma experiment and initial results which should give insight into the magnetic dynamics of accretion discs and jets. A high-speed multiple-frame CCD camera reveals images of the formation and helical instability of a collimated plasma, similar to MHD models of disc jets, and also plasma detachment associated with spheromak formation, which may have relevance to disc winds and flares. The plasmas are produced by a planar magnetized coaxial gun. The resulting magnetic topology is dependent on the details of magnetic helicity injection, namely the force-free state eigenvalue alpha_gun imposed by the coaxial gun.

  14. Studying Nanoscale Magnetism and its Dynamics with Soft X-ray Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mccall, Monnikue M; Fischer, Peter

    2008-05-01

    Magnetic soft X-ray microscopy allows for imaging magnetic structures at a spatial resolution down to 15nm and a time resolution in the sub-100ps regime. Inherent elemental specificity can be used to image the magnetic response of individual components such as layers in multilayered systems. This review highlights current achievements and discusses the future potential of magnetic soft X-ray microscopy at fsec X-ray sources where snapshot images of ultrafast spin dynamics with a spatial resolution below 10nm will become feasible.

  15. The Influence of Helical Magnetic Fields in the Dynamics and Emission of Relativistic Jets

    CERN Document Server

    Roca-Sogorb, M; Gómez, J L; Martí, J M; Antón, L; Aloy, M A; Agudo, I

    2008-01-01

    We present numerical relativistic magnetohydrodynamic and emission simulations aimed to study the role played by the magnetic field in the dynamics and emission of relativistic jets in Active Galactic Nuclei. We focus our analysis on the study of the emission from recollimation shocks since they may provide an interpretation for the stationary components seen at parsec-scales in multiple sources. We show that the relative brightness of the knots associated with the recollimation shocks decreases with increasing jet magnetization, suggesting that jets presenting stationary components may have a relatively weak magnetization, with magnetic fields of the order of equipartition or below.

  16. Aggregation dynamics and magnetic properties of magnetic micrometer-sized particles dispersed in a fluid under the action of rotating magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Llera, María [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Codnia, Jorge [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Centro de Investigaciones en Láseres y Aplicaciones, CITEDEF-CONICET, Buenos Aires (Argentina); Jorge, Guillermo A., E-mail: gjorge@ungs.edu.ar [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina)

    2015-06-15

    We present a dynamic study of soft magnetic, commercial Fe and Ni micrometer-sized particles dispersed in oleic acid and subjected to a variable (rotating) magnetic field in the horizontal plane. A very complex structure is formed after the particles decant towards the bottom liquid–solid interface and the magnetic field is applied for several minutes. The dynamics of structure formation was studied by means of the registration and analysis of microscopic video images, through a Matlab image analysis script. Several parameters, such as the number of clusters, the perimeter-based fractal dimension and circularity, were calculated as a function of time. The time evolution of the number of clusters was found to follow a power-law behavior, with an exponent consistent with that found in other studies for magnetic systems, whereas the typical formation time depends on the particle diameter and field configuration. Complementarily, the magnetic properties of the formed structure were studied, reproducing the experiment with liquid paraffin as the containing fluid, and then letting it solidify. The sample obtained was studied by vibrating sample magnetometry. The magnetization curves show that the material obtained is a planar magnetically anisotropic material, which could eventually be used as an anisotropic magnetic sensor or actuator. - Highlights: • Dynamic study of Fe and Ni particles in oleic acid under rotating fields. • A very complex system of interconnected clusters was observed. • Larger particles had a smaller aggregation time. • A power law behavior of the number of clusters vs. time. • A Fe-paraffin sample with planar anisotropy characterized.

  17. Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

    Directory of Open Access Journals (Sweden)

    Kazuto eKodama

    2015-02-01

    Full Text Available This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM. These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization–field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

  18. Shell thickness and dynamic magnetic field effects on the critical phenomena of magnetic core-shell nanoparticles with spherical geometry

    Science.gov (United States)

    Yüksel, Yusuf

    2017-03-01

    By using Monte Carlo simulations for classical Heisenberg spins, we study the critical phenomena and ferrimagnetic properties of spherical nanoparticles with core-shell geometry. The particle core is composed of ferromagnetic spins, and it is coated by a ferromagnetic shell. Total size of the particle is fixed but the thickness of the shell is varied in such a way that the shell layer is grown at the expense of the core. Effects of the shell thickness, as well as dynamic magnetic field parameters such as oscillation period and field amplitude on the magnetization profiles, dynamic hysteresis loops and phase diagrams have been investigated for the present system. It has been found that as the shell thickness varies then the easy axis magnetization of the overall system may exhibit Q-, P-, L- and N- type behaviors based on the Neél terminology. We also found that three distinct anomalies originate in the thermal variation of specific heat with increasing field period. Dynamic hysteresis loops corresponding to off-axial magnetization components exhibit unconventional behavior such as double rings with symmetric shapes around the vertical axis over the h (t) = 0 line which may originate due to the stochastic resonance behavior of these components.

  19. Field theory of bicritical and tetracritical points. III. Relaxational dynamics including conservation of magnetization (model C).

    Science.gov (United States)

    Folk, R; Holovatch, Yu; Moser, G

    2009-03-01

    We calculate the relaxational dynamical critical behavior of systems of O(n_{ parallel}) plus sign in circleO(n_{ perpendicular}) symmetry including conservation of magnetization by renormalization group theory within the minimal subtraction scheme in two-loop order. Within the stability region of the Heisenberg fixed point and the biconical fixed point, strong dynamical scaling holds, with the asymptotic dynamical critical exponent z=2varphinu-1 , where varphi is the crossover exponent and nu the exponent of the correlation length. The critical dynamics at n_{ parallel}=1 and n_{ perpendicular}=2 is governed by a small dynamical transient exponent leading to nonuniversal nonasymptotic dynamical behavior. This may be seen, e.g., in the temperature dependence of the magnetic transport coefficients.

  20. Role of helicities for the dynamics of turbulent magnetic fields

    CERN Document Server

    Mueller, Wollf-Christian

    2013-01-01

    Investigations of the inverse cascade of magnetic helicity are conducted with pseudospectral, three-dimensional direct numerical simulations of forced and decaying incompressible magnetohydrodynamic turbulence. The high-resolution simulations which allow for the necessary scale-separation show that the observed self-similar scaling behavior of magnetic helicity and related quantities can only be understood by taking the full nonlinear interplay of velocity and magnetic fluctuations into account. With the help of the eddy-damped quasi-normal Markovian approximation a probably universal relation between kinetic and magnetic helicities is derived that closely resembles the extended definition of the prominent dynamo pseudoscalar $\\alpha$. This unexpected similarity suggests an additional nonlinear quenching mechanism of the current-helicity contribution to $\\alpha$.

  1. Magnetism of metals in the dynamic spin-fluctuation theory

    Science.gov (United States)

    Melnikov, N. B.; Reser, B. I.

    2016-12-01

    We overview new developments in spin-fluctuation theory, which describes magnetic properties of ferromagnetic metals at finite temperatures. We present a detailed analysis of the underlying techniques and compare numerical results with experiment.

  2. Dynamics of Magnetic Nanoparticles Studied by Neutron Scattering

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Bødker, Franz; Mørup, Steen

    1997-01-01

    We present the first triple-axis neutron scattering measurements of magnetic fluctuations in nanoparticles using an antiferromagnetic reflection. Both the superparamagnetic relaxation and precession modes in similar to 15 nm hematite particles are: observed. The results have been consistently...

  3. Value of dynamic enhanced MRI (DCE-MRI)in diagnosing the breast fibroadenoma and breast carcinoma%MRI动态增强扫描对乳腺纤维腺瘤和乳腺癌的诊断价值

    Institute of Scientific and Technical Information of China (English)

    梅莉; 郑建刚; 王开香; 许建兴; 刘良卿; 顾勇坚; 周鸿雁

    2013-01-01

    目的 探讨乳腺纤维腺瘤和乳腺癌的MRI动态增强表现,以期提高对乳腺疾病的诊断准确性.方法 回顾性分析30例经手术或穿刺病理证实的乳腺纤维腺瘤和乳腺癌患者的MRI资料,分析病灶的形态特征、动态增强特征,以及病灶的时间-信号强度曲线(TIC)表达.结果 30例患者共53个病灶,其中乳腺纤维腺瘤病灶38个,乳腺癌病灶15个.乳腺纤维腺瘤边界大多较清晰光整,且增强后强化均匀或不强化,TIC表达主要为Ⅰ型,占78.95%.乳腺癌的形态多表现为不规则或毛刺状,强化不均匀,TIC以Ⅲ型为主,占60.00%.二者在Ⅱ型TIC上有交叉.结论 MRI动态增强扫描可以提高病灶的检出率,能更好地鉴别乳腺癌和乳腺纤维腺瘤.%Objective To investigate the imaging appearance of breast fibroadenoma and breast carcinoma by the dynamic enhanced MRI(DCE - MRI), and improve the diagnostic accuracy of the breast diseases. Methods Imaging data of 30 patients with breast fibroadenoma and breast carcinoma proved by operation or biopsy were retrospectively analized. MR imaging features of morphology, dynamic enhancement pattern, and the time-signal intensity curve(TIC) were evaluated. Results Among the 30 patients with 53 breast lesions, 38 were having breast fibroadenoma, 15 breast carcinoma. Most breast fibroadenoma cases showed smooth and tidy borders, homogeneous enhancement or no enhancement. Type Ⅰ TIC were observed in most cases(78.95%). While most breast carcinoma showed irregular shape or speculated margin, and heterogeneous enhancement or rim enhancement. Type Ⅲ TIC curves were observed in most breast carcinoma (60.00%). Type Ⅱ TIC curves were found in both breast fibroadenoma and breast carcinoma. Conclusion DCE -MRI can improve the lesions' relevance ratio of breast diseases, and is helpful in diagnosing the difference between breast fibroadenoma and breast carcinoma.

  4. Nonlinear dynamics of breathers in the spiral structures of magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, V. V., E-mail: kiselev@imp.uran.ru; Raskovalov, A. A. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-06-15

    The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of “precursors” and “tails” in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.

  5. Dynamics of magnetic nano-flake vortices in Newtonian fluids

    Energy Technology Data Exchange (ETDEWEB)

    Bazazzadeh, Nasim, E-mail: n.bazazzadeh@gmail.com [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Mohseni, Seyed Majid, E-mail: m-mohseni@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Khavasi, Amin, E-mail: khavasi@sharif.edu [Department of Electrical Engineering, Sharif University of Technology, Tehran 11555-4363 (Iran, Islamic Republic of); Zibaii, Mohammad Ismail, E-mail: mizibaye@gmail.com [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Movahed, S.M.S., E-mail: m_movahed@sbu.ac.ir [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of); Jafari, G.R., E-mail: gjafari@gmail.com [Department of Physics, Shahid Beheshti University, G.C., Evin, Tehran 19839 (Iran, Islamic Republic of)

    2016-12-01

    We study the rotational motion of nano-flake ferromagnetic disks suspended in a Newtonian fluid, as a potential material owing the vortex-like magnetic configuration. Using analytical expressions for hydrodynamic, magnetic and Brownian torques, the stochastic angular momentum equation is determined in the dilute limit conditions under applied magnetic field. Results are compared against experimental ones and excellent agreement is observed. We also estimate the uncertainty in the orientation of the disks due to the Brownian torque when an external magnetic field aligns them. Interestingly, this uncertainty is roughly proportional to the ratio of thermal energy of fluid to the magnetic energy stored in the disks. Our approach can be implemented in many practical applications including biotechnology and multi-functional fluidics. - Highlights: • The rotational motion of magnetic-vortex microdiscs in a Newtonian fluid is studied. • Results are compared against experimental ones and excellent agreement is observed. • The uncertainty in the orientation of the microdiscs is analytically derived.

  6. A Model of Charge Transfer Excitons: Diffusion, Spin Dynamics, and Magnetic Field Effects

    CERN Document Server

    Lee, Chee Kong; Willard, Adam P

    2016-01-01

    In this letter we explore how the microscopic dynamics of charge transfer (CT) excitons are influenced by the presence of an external magnetic field in disordered molecular semiconductors. This influence is driven by the dynamic interplay between the spin and spatial degrees of freedom of the electron-hole pair. To account for this interplay we have developed a numerical framework that combines a traditional model of quantum spin dynamics with a coarse-grained model of stochastic charge transport. This combination provides a general and efficient methodology for simulating the effects of magnetic field on CT state dynamics, therefore providing a basis for revealing the microscopic origin of experimentally observed magnetic field effects. We demonstrate that simulations carried out on our model are capable of reproducing experimental results as well as generating theoretical predictions related to the efficiency of organic electronic materials.

  7. Flow dynamics and magnetic induction in the von-Karman plasma experiment

    CERN Document Server

    Plihon, Nicolas; Palermo, Francesco; Morales, Jorge A; Bos, Wouter; Godeferd, Fabien S; Bourgoin, Mickaël; Pinton, Jean-François; Moulin, M; Aanesland, Ane

    2014-01-01

    The von-Karman plasma experiment is a novel versatile experimental device designed to explore the dynamics of basic magnetic induction processes and the dynamics of flows driven in weakly magnetized plasmas. A high-density plasma column (10^16 - 10^19 particles.m^-3) is created by two radio-frequency plasma sources located at each end of a 1 m long linear device. Flows are driven through JxB azimuthal torques created from independently controlled emissive cathodes. The device has been designed such that magnetic induction processes and turbulent plasma dynamics can be studied from a variety of time-averaged axisymmetric flows in a cylinder. MHD simulations implementing volume-penalization support the experimental development to design the most efficient flow-driving schemes and understand the flow dynamics. Preliminary experimental results show that a rotating motion of up to nearly 1 km/s is controlled by the JxB azimuthal torque.

  8. Tamoxifen integromics and personalized medicine: dynamic modular transformations underpinning response to tamoxifen in breast cancer treatment.

    Science.gov (United States)

    Dimitrakopoulou, Konstantina; Dimitrakopoulos, Georgios N; Sgarbas, Kyriakos N; Bezerianos, Anastasios

    2014-01-01

    Recent advances in pharmacogenomics technologies allow bold steps to be taken towards personalized medicine, more accurate health planning, and personalized drug development. In this framework, systems pharmacology network-based approaches offer an appealing way for integrating multi-omics data and set the basis for defining systems-level drug response biomarkers. On the road to individualized tamoxifen treatment in estrogen receptor-positive breast cancer patients, we examine the dynamics of the attendant pharmacological response mechanisms. By means of an "integromics" network approach, we assessed the tamoxifen effect through the way the high-order organization of interactome (i.e., the modules) is perturbed. To accomplish that, first we integrated the time series transcriptome data with the human protein interaction data, and second, an efficient module-detecting algorithm was applied onto the composite graphs. Our findings show that tamoxifen induces severe modular transformations on specific areas of the interactome. Our modular biomarkers in response to tamoxifen attest to the immunomodulatory role of tamoxifen, and further reveal that it deregulates cell cycle and apoptosis pathways, while coordinating the proteasome and basal transcription factors. To the best of our knowledge, this is the first report that informs the fields of personalized medicine and clinical pharmacology about the actual dynamic interactome response to tamoxifen administration.

  9. Personal and Network Dynamics in Performance of Knowledge Workers: A Study of Australian Breast Radiologists.

    Directory of Open Access Journals (Sweden)

    Seyedamir Tavakoli Taba

    Full Text Available In this paper, we propose a theoretical model based upon previous studies about personal and social network dynamics of job performance. We provide empirical support for this model using real-world data within the context of the Australian radiology profession. An examination of radiologists' professional network topology through structural-positional and relational dimensions and radiologists' personal characteristics in terms of knowledge, experience and self-esteem is provided. Thirty one breast imaging radiologists completed a purpose designed questionnaire regarding their network characteristics and personal attributes. These radiologists also independently read a test set of 60 mammographic cases: 20 cases with cancer and 40 normal cases. A Jackknife free response operating characteristic (JAFROC method was used to measure the performance of the radiologists' in detecting breast cancers.Correlational analyses showed that reader performance was positively correlated with the social network variables of degree centrality and effective size, but negatively correlated with constraint and hierarchy. For personal characteristics, the number of mammograms read per year and self-esteem (self-evaluation positively correlated with reader performance. Hierarchical multiple regression analysis indicated that the combination of number of mammograms read per year and network's effective size, hierarchy and tie strength was the best fitting model, explaining 63.4% of the variance in reader performance. The results from this study indicate the positive relationship between reading high volumes of cases by radiologists and expertise development, but also strongly emphasise the association between effective social/professional interactions and informal knowledge sharing with high performance.

  10. Thermally driven transverse transports and magnetic dynamics on a topological surface capped with a ferromagnet strip

    Science.gov (United States)

    Deng, Ming-Xun; Zhong, Ming; Zheng, Shi-Han; Qiu, Jian-Ming; Yang, Mou; Wang, Rui-Qiang

    2016-02-01

    We theoretically study thermally driven transport of the Dirac fermions on the surface of a topological insulator capped with a ferromagnet strip. The generation and manipulation of anomalous Hall and Nernst effects are analyzed, in which the in-plane magnetization of the ferromagnet film is found to take a decisive role. This scenario is distinct from that modulated by Berry phase where the in-plane magnetization is independent. We further discuss the thermal spin-transfer torque as a backaction of the thermoelectric transports on the magnetization and calculate the dynamics of the anomalous Hall and Nernst effects self-consistently. It is found that the magnitude of the long-time steady Hall and Nernst conductance is determined by competition between the magnetic anisotropy and current-induced effective anisotropy. These results open up a possibility of magnetically controlling the transverse thermoelectric transports or thermally manipulating the magnet switching.

  11. Dynamic effects on the stretching of the magnetic field by a plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, Manuel [Departamento de Analisis Matematico, Universidad de Valladolid, 47005 Valladolid (Spain)

    2003-08-22

    A key mechanism in the growth of magnetic energy in kinematic dynamos is the stretching of the magnetic field vector by making it point in an unstable direction of the strain matrix. Our objective is to study whether this feature may be maintained in an ideal plasma when also considering the back reaction of the magnetic field upon the flow through the Lorentz force. Several effects occur: in addition to the nonlocal ones exerted by the total pressure, a complex geometry of magnetic field lines decreases the rate of growth of magnetic energy, rotation of the flow enhances it and above all the rate of growth decreases with minus the square of the eigenvalue associated with the magnetic field direction. Thus local dynamics tend to rapidly quench the stretching of the field.

  12. First Flare-related Rapid Change of Photospheric Magnetic Field Observed by Solar Dynamics Observatory

    CERN Document Server

    Wang, Shuo; Liu, Rui; Deng, Na; Liu, Yang; Wang, Haimin

    2011-01-01

    Photospheric magnetic field not only plays important roles in building up free energy and triggering solar eruptions, but also has been observed to change rapidly and permanently responding to the coronal magnetic field restructuring due to coronal transients. The Helioseismic and Magnetic Imager instrument (HMI) on board the newly launched Solar Dynamics Observatory (SDO) produces seeing-free full-disk vector magnetograms at consistently high resolution and high cadence, which finally makes possible an unambiguous and comprehensive study of this important back-reaction process. In this study, we present a near disk-center, GOES-class X2.2 flare occurred at NOAA AR 11158 on 2011 February 15 using the magnetic field measurements made by HMI. We obtained the first solid evidence of an enhancement in the transverse magnetic field at the flaring magnetic polarity inversion line (PIL) by a magnitude of 70%. This rapid and irreversible field evolution is unequivocally associated with the flare occurrence, with the ...

  13. Magnetization and microstructure dynamics in Fe/MnAs/GaAs(001): Fe magnetization reversal by a femtosecond laser pulse.

    Science.gov (United States)

    Spezzani, C; Ferrari, E; Allaria, E; Vidal, F; Ciavardini, A; Delaunay, R; Capotondi, F; Pedersoli, E; Coreno, M; Svetina, C; Raimondi, L; Zangrando, M; Ivanov, R; Nikolov, I; Demidovich, A; Danailov, M B; Popescu, H; Eddrief, M; De Ninno, G; Kiskinova, M; Sacchi, M

    2014-12-12

    Thin film magnetization reversal without applying external fields is an attractive perspective for applications in sensors and devices. One way to accomplish it is by fine-tuning the microstructure of a magnetic substrate via temperature control, as in the case of a thin Fe layer deposited on a MnAs/GaAs(001) template. This work reports a time-resolved resonant scattering study exploring the magnetic and structural properties of the Fe/MnAs system, using a 100 fs optical laser pulse to trigger local temperature variations and a 100 fs x-ray free-electron laser pulse to probe the induced magnetic and structural dynamics. The experiment provides direct evidence that a single optical laser pulse can reverse the Fe magnetization locally. It reveals that the time scale of the magnetization reversal is slower than that of the MnAs structural transformations triggered by the optical pulse, which take place after a few picoseconds already.

  14. Spin currents and magnon dynamics in insulating magnets

    Science.gov (United States)

    Nakata, Kouki; Simon, Pascal; Loss, Daniel

    2017-03-01

    Nambu–Goldstone theorem provides gapless modes to both relativistic and nonrelativistic systems. The Nambu–Goldstone bosons in insulating magnets are called magnons or spin-waves and play a key role in magnetization transport. We review here our past works on magnetization transport in insulating magnets and also add new insights, with a particular focus on magnon transport. We summarize in detail the magnon counterparts of electron transport, such as the Wiedemann–Franz law, the Onsager reciprocal relation between the Seebeck and Peltier coefficients, the Hall effects, the superconducting state, the Josephson effects, and the persistent quantized current in a ring to list a few. Focusing on the electromagnetism of moving magnons, i.e. magnetic dipoles, we theoretically propose a way to directly measure magnon currents. As a consequence of the Mermin–Wagner–Hohenberg theorem, spin transport is drastically altered in one-dimensional antiferromagnetic (AF) spin-1/2 chains; where the Néel order is destroyed by quantum fluctuations and a quasiparticle magnon-like picture breaks down. Instead, the low-energy collective excitations of the AF spin chain are described by a Tomonaga–Luttinger liquid (TLL) which provides the spin transport properties in such antiferromagnets some universal features at low enough temperature. Finally, we enumerate open issues and provide a platform to discuss the future directions of magnonics.

  15. Dynamics and shapes of ferrofluid drops under spatially uniform magnetic fields

    Science.gov (United States)

    Rowghanian, Payam; Serwane, Friedhelm; Kealhofer, David; Meinhart, Carl D.; Campas, Otger

    2016-11-01

    We study the shape and dynamics of a Newtonian ferrofluid drop immersed in a Newtonian and non-magnetic viscous fluid under the action of a uniform external magnetic field. We obtain the exact equilibrium drop shapes for arbitrary ferrofluids which describe unexplained previous experiments, characterize the extent of deviations of the exact shape from the commonly assumed ellipsoidal shape, and analyze the smoothness of highly curved tips in elongated drops. We present a comprehensive study of drop deformation for a Langevin ferrofluid. Using a computational scheme that allows fast and accurate simulations of ferrofluid drop dynamics, we show that the dynamics of drop deformation by an applied magnetic field is described up to a numerical factor by the same time scale as drop relaxation in the absence of any magnetic field. The numerical factor depends on the ratio of viscosities and the ratio of magnetic to capillary stresses, but is independent of the nature of the ferrofluid in most practical cases. Finally, we use the shape and dynamics of the magnetic drops to measure the rheology of complex fluids.

  16. Asymmetric driven dynamics of Dzyaloshinskii domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy

    Science.gov (United States)

    Sánchez-Tejerina, L.; Alejos, Ó.; Martínez, E.; Muñoz, J. M.

    2016-07-01

    The dynamics of domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy is studied from both numerical and analytical micromagnetics. The influence of a moderate interfacial Dzyaloshinskii-Moriya interaction associated to a bi-layer strip arrangement has been considered, giving rise to the formation of Dzyaloshinskii domain walls. Such walls possess under equilibrium conditions an inner magnetization structure defined by a certain orientation angle that make them to be considered as intermediate configurations between Bloch and Néel walls. Two different dynamics are considered, a field-driven and a current-driven dynamics, in particular, the one promoted by the spin torque due to the spin-Hall effect. Results show an inherent asymmetry associated with the rotation of the domain wall magnetization orientation before reaching the stationary regime, characterized by a constant terminal speed. For a certain initial DW magnetization orientation at rest, the rotation determines whether the reorientation of the DW magnetization prior to reach stationary motion is smooth or abrupt. This asymmetry affects the DW motion, which can even reverse for a short period of time. Additionally, it is found that the terminal speed in the case of the current-driven dynamics may depend on either the initial DW magnetization orientation at rest or the sign of the longitudinally injected current.

  17. A novel approach to identify non-palpable breast lesions combining fluorescent liposomes and magnetic resonance-guided high intensity focused ultrasound-triggered release

    NARCIS (Netherlands)

    Oerlemans, Chris; Nijsen, Frank; van Amersfoort, Miranda; van Bloois, Louis; Heijman, Edwin; Luijten, Peter; Mali, Willem; Storm, Gert

    2011-01-01

    The combination of fluorescein-containing liposomes (FCL) and magnetic resonance-guided high intensity focused ultrasound (MR-HIFU)-triggered release is a promising approach for lesion demarcation and more efficient removal of non-palpable breast lesions. Exposure of FCL to ablation temperatures (60

  18. Static and Dynamic Magnetization Investigation in Permalloy Electrodeposited onto High Resistive N-Type Silicon Substrates

    Directory of Open Access Journals (Sweden)

    Kenedy Freitas

    2017-02-01

    Full Text Available The present study reports on the development of permalloy thin films obtained by electrodeposition onto low-doped n-type silicon substrates. While changing from non-percolated clusters into percolated thin films upon increasing the electrodeposition time, the static and dynamic magnetic properties of the as-obtained structures were investigated. We found the experimental magnetic results to be in very good agreement with the simulations performed by solving the Landau-Lifshitz for the dynamics of the magnetic moment. For short electrodeposition times we found the static and dynamic magnetization behavior of the as-formed nanoclusters evidencing vortex magnetization with random chirality and polarization, which is explained in terms of dipolar interaction minimization. Indeed, it is herein emphasized that recent applications of ferromagnetic materials in silicon-based spintronic devices, such as logic and bipolar magnetic transistors and magnetic memories, have revived the possible utilization of low cost and simple electrodeposition techniques for the development of these upcoming hetero-nanostructured devices.

  19. Dynamic and biocompatible thermo-responsive magnetic hydrogels that respond to an alternating magnetic field

    Science.gov (United States)

    Crippa, Federica; Moore, Thomas L.; Mortato, Mariangela; Geers, Christoph; Haeni, Laetitia; Hirt, Ann M.; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

    2017-04-01

    Magnetic thermo-responsive hydrogels are a new class of materials that have recently attracted interest in biomedicine due to their ability to change phase upon magnetic stimulation. They have been used for drug release, magnetic hyperthermia treatment, and can potentially be engineered as stimuli-responsive substrates for cell mechanobiology. In this regard, we propose a series of magnetic thermo-responsive nanocomposite substrates that undergo cyclical swelling and de-swelling phases when actuated by an alternating magnetic field in aqueous environment. The synthetized substrates are obtained with a facile and reproducible method from poly-N-isopropylacrylamide and superparamagnetic iron oxide nanoparticles. Their conformation and the temperature-related, magnetic, and biological behaviors were characterized via scanning electron microscopy, swelling ratio analysis, vibrating sample magnetometry, alternating magnetic field stimulation and indirect viability assays. The nanocomposites showed no cytotoxicity with fibroblast cells, and exhibited swelling/de-swelling behavior near physiological temperatures (around 34 °C). Therefore these magnetic thermo-responsive hydrogels are promising materials as stimuli-responsive substrates allowing the study of cell-behavior by changing the hydrogel properties in situ.

  20. Local Dynamical Instabilities in Magnetized, Radiation Pressure Supported Accretion Disks

    CERN Document Server

    Blaes, Omer M; Blaes, Omer; Socrates, Aristotle

    2000-01-01

    We present a general linear dispersion relation which describes the coupled behavior of magnetorotational, photon bubble, and convective instabilities in weakly magnetized, differentially rotating accretion disks. We presume the accretion disks to be geometrically thin and supported vertically by radiation pressure. We fully incorporate the effects of a nonzero radiative diffusion length on the linear modes. In an equilibrium with purely vertical magnetic field, the vertical magnetorotational modes are completely unaffected by compressibility, stratification, and radiative diffusion. However, in the presence of azimuthal fields, which are expected in differentially rotating flows, the growth rate of all magnetorotational modes can be reduced substantially below the orbital frequency. This occurs if diffusion destroys radiation sound waves on the length scale of the instability, and the magnetic energy density of the azimuthal component exceeds the non-radiative thermal energy density. While sluggish in this c...

  1. Closing the hierarchy for non-Markovian magnetization dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Tranchida, J., E-mail: julien.tranchida@cea.fr [CEA/DAM/Le Ripault, BP 16, F-37260 Monts (France); CNRS-Laboratoire de Mathématiques et Physique Théorique (UMR 7350), Fédération de Recherche “Denis Poisson” (FR2964), Département de Physique, Université de Tours, Parc de Grandmont, F-37200 Tours (France); Thibaudeau, P., E-mail: pascal.thibaudeau@cea.fr [CEA/DAM/Le Ripault, BP 16, F-37260 Monts (France); Nicolis, S., E-mail: stam.nicolis@lmpt.univ-tours.fr [CNRS-Laboratoire de Mathématiques et Physique Théorique (UMR 7350), Fédération de Recherche “Denis Poisson” (FR2964), Département de Physique, Université de Tours, Parc de Grandmont, F-37200 Tours (France)

    2016-04-01

    We propose a stochastic approach for the description of the time evolution of the magnetization of nanomagnets, that interpolates between the Landau–Lifshitz–Gilbert and the Landau–Lifshitz–Bloch approximations, by varying the strength of the noise. In addition, we take into account the autocorrelation time of the noise and explore the consequences, when it is finite, on the scale of the response of the magnetization, i.e. when it may be described as colored, rather than white, noise and non-Markovian features become relevant. We close the hierarchy for the moments of the magnetization, by introducing a suitable truncation scheme, whose validity is tested by direct numerical solution of the moment equations and compared to the average deduced from a numerical solution of the corresponding stochastic Langevin equation. In this way we establish a general framework that allows both coarse-graining simulations and faster calculations beyond the truncation approximation used here.

  2. Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

    Directory of Open Access Journals (Sweden)

    OZCIRA, S.

    2010-05-01

    Full Text Available Permanent magnet DC motor-generators (PMDC, PMSG have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output.

  3. Rotating magnetic particle microrheometry in biopolymer fluid dynamics: mucus microrheology.

    Science.gov (United States)

    Besseris, George J; Yeates, Donovan B

    2007-09-14

    The polymer properties of canine mucus were investigated through the method of rotating magnetic particle microrheometry. Mucus is visualized as a physically entangled biopolymer of low polydispersity in a water-based solution. Mucus was modeled according to the constitutive law of a Doi-Edwards fluid. The magnetic-particle equation of rotational motion is analytically solved in the linear viscoelastic limit rendering theoretical flow profiles which are used to fit the experimental trace signals of the particle remanent-magnetic-field decay. The zero-shear-rate viscosity was found to be 18,000 P and the relaxation time at about 42 s. The molecular weight between entanglements for mucins was estimated at 1.7 MDa rendering an estimation of about seven physical cross-links per molecule. Rheological investigations were extended also to diluted and concentrated rations of the normal mucus simulating the conditions found in more physiological extremes.

  4. Self-similar dynamics of a magnetized polytropic gas

    Science.gov (United States)

    Wang, Wei-Gang; Lou, Yu-Qing

    2007-10-01

    In broad astrophysical contexts of large-scale gravitational collapses and outflows and as a basis for various further astrophysical applications, we formulate and investigate a theoretical problem of self-similar magnetohydrodynamics (MHD) for a non-rotating polytropic gas of quasi-spherical symmetry permeated by a completely random magnetic field. Within this framework, we derive two coupled nonlinear MHD ordinary differential equations (ODEs), examine properties of the magnetosonic critical curve, obtain various asymptotic and global semi-complete similarity MHD solutions, and qualify the applicability of our results. Unique to a magnetized gas cloud, a novel asymptotic MHD solution for a collapsing core is established. Physically, the similarity MHD inflow towards the central dense core proceeds in characteristic manners before the gas material eventually encounters a strong radiating MHD shock upon impact onto the central compact object. Sufficiently far away from the central core region enshrouded by such an MHD shock, we derive regular asymptotic behaviours. We study asymptotic solution behaviours in the vicinity of the magnetosonic critical curve and determine smooth MHD eigensolutions across this curve. Numerically, we construct global semi-complete similarity MHD solutions that cross the magnetosonic critical curve zero, one, and two times. For comparison, counterpart solutions in the case of an isothermal unmagnetized and magnetized gas flows are demonstrated in the present MHD framework at nearly isothermal and weakly magnetized conditions. For a polytropic index γ=1.25 or a strong magnetic field, different solution behaviours emerge. With a strong magnetic field, there exist semi-complete similarity solutions crossing the magnetosonic critical curve only once, and the MHD counterpart of expansion-wave collapse solution disappears. Also in the polytropic case of γ=1.25, we no longer observe the trend in the speed-density phase diagram of finding

  5. Distributed optical fiber dynamic magnetic field sensor based on magnetostriction.

    Science.gov (United States)

    Masoudi, Ali; Newson, Trevor P

    2014-05-01

    A distributed optical fiber sensor is introduced which is capable of quantifying multiple magnetic fields along a 1 km sensing fiber with a spatial resolution of 1 m. The operation of the proposed sensor is based on measuring the magnetorestrictive induced strain of a nickel wire attached to an optical fiber. The strain coupled to the optical fiber was detected by measuring the strain-induced phase variation between the backscattered Rayleigh light from two segments of the sensing fiber. A magnetic field intensity resolution of 0.3 G over a bandwidth of 50-5000 Hz was demonstrated.

  6. Joint estimation of shape and deformation for the detection of lesions in dynamic contrast-enhanced breast MRI

    Science.gov (United States)

    Hong, Byung-Woo

    2013-11-01

    We propose a mathematical framework for simultaneously delineating the boundary of object and estimating its temporal motion in the application of lesion detection in a dynamic contrast-enhanced (DCE) breast MRI sequence where both the appearance and the shape of region of interest is assumed to change in time. A unified energy functional for a joint segmentation and registration is proposed based on the assumption that the statistical properties of dynamic intensity curves within a region of interest are homogeneous. Our algorithm is designed to provide the morphological properties of the enhanced region and its dynamic intensity profiles, called kinetic signatures, in the analysis of DCE imagery since these features are considered as significant cues in understanding images. The proposed energy comprises a combination of a segmentation energy and a registration energy. The segmentation energy is developed based on a convex formulation being insensitive to the initialization. The registration energy is designed to compensate motion artifacts that are usually involved in the temporal imaging procedure. The major objective of this work is to provide a mathematical framework for a joint segmentation and registration on a dynamic sequence of images, and we demonstrate the mutual benefit of the estimation of temporal deformations for the registration step and the localization of regions of interest for the segmentation step. The effectiveness of the developed algorithm has been demonstrated on a number of clinical DCE breast MRI data in the application of breast lesion detection and the results show its potential to improve the accuracy and the efficiency in the diagnosis of breast cancer.

  7. Phase-dependent dynamic potential of magnetically coupled two-degree-of-freedom bistable energy harvester

    Science.gov (United States)

    Kim, Pilkee; Nguyen, Minh Sang; Kwon, Ojin; Kim, Young-Jin; Yoon, Yong-Jin

    2016-09-01

    A system of magnetically coupled oscillators has been recently considered as a promising compact structure to integrate multiple bistable energy harvesters (BEHs), but its design is not straightforward owing to its varying potential energy pattern, which has not been understood completely yet. This study introduces the concept of phase-dependent dynamic potential in a magnetically coupled BEH system with two degrees of freedom (DOFs) to explain the underlying principle of the complicated dynamics of the system. Through theoretical simulations and analyses, two distinct dynamic regimes, called the out-of-phase and in-phase mode regimes in this report, are found to exist in the frequency regions of the 1st and 2nd primary intrawell resonances. For the out-of-phase mode regime, the frequency displacement (and output power) responses of the 2-DOF BEH system exhibit typical double-well dynamics, whereas for the in-phase mode regime, only single-well dynamics is observed though the system is statically bistable. These dynamic regimes are also revealed to be caused by the difference in the dynamic potential energy trajectories propagating on a high-dimensional potential energy surface. The present approach to the dynamics of the 2-DOF BEH system can be extended and applied to higher-DOF systems, which sheds light on compact and efficient designs of magnetically coupled BEH chain structures.

  8. Phase-dependent dynamic potential of magnetically coupled two-degree-of-freedom bistable energy harvester

    Science.gov (United States)

    Kim, Pilkee; Nguyen, Minh Sang; Kwon, Ojin; Kim, Young-Jin; Yoon, Yong-Jin

    2016-01-01

    A system of magnetically coupled oscillators has been recently considered as a promising compact structure to integrate multiple bistable energy harvesters (BEHs), but its design is not straightforward owing to its varying potential energy pattern, which has not been understood completely yet. This study introduces the concept of phase-dependent dynamic potential in a magnetically coupled BEH system with two degrees of freedom (DOFs) to explain the underlying principle of the complicated dynamics of the system. Through theoretical simulations and analyses, two distinct dynamic regimes, called the out-of-phase and in-phase mode regimes in this report, are found to exist in the frequency regions of the 1st and 2nd primary intrawell resonances. For the out-of-phase mode regime, the frequency displacement (and output power) responses of the 2-DOF BEH system exhibit typical double-well dynamics, whereas for the in-phase mode regime, only single-well dynamics is observed though the system is statically bistable. These dynamic regimes are also revealed to be caused by the difference in the dynamic potential energy trajectories propagating on a high-dimensional potential energy surface. The present approach to the dynamics of the 2-DOF BEH system can be extended and applied to higher-DOF systems, which sheds light on compact and efficient designs of magnetically coupled BEH chain structures. PMID:27677356

  9. Non-equilibrium magnetic colloidal dispersions at liquid-air interfaces: dynamic patterns, magnetic order and self-assembled swimmers.

    Science.gov (United States)

    Snezhko, Alexey

    2011-04-20

    Colloidal dispersions of interacting particles subjected to an external periodic forcing often develop nontrivial self-assembled patterns and complex collective behavior. A fundamental issue is how collective ordering in such non-equilibrium systems arises from the dynamics of discrete interacting components. In addition, from a practical viewpoint, by working in regimes far from equilibrium new self-organized structures which are generally not available through equilibrium thermodynamics can be created. In this review spontaneous self-assembly phenomena in magnetic colloidal dispersions suspended at liquid-air interfaces and driven out of equilibrium by an alternating magnetic field are presented. Experiments reveal a new type of nontrivially ordered self-assembled structures emerging in such systems in a certain range of excitation parameters. These dynamic structures emerge as a result of the competition between magnetic and hydrodynamic forces and have complex unconventional magnetic ordering. Nontrivial self-induced hydrodynamic fields accompany each out-of-equilibrium pattern. Spontaneous symmetry breaking of the self-induced surface flows leading to a formation of self-propelled microstructures has been discovered. Some features of the self-localized structures can be understood in the framework of the amplitude equation (Ginzburg-Landau type equation) for parametric waves coupled to the conservation law equation describing the evolution of the magnetic particle density and the Navier-Stokes equation for hydrodynamic flows. To understand the fundamental microscopic mechanisms governing self-assembly processes in magnetic colloidal dispersions at liquid-air interfaces a first-principle model for a non-equilibrium self-assembly is presented. The latter model allows us to capture in detail the entire process of out-of-equilibrium self-assembly in the system and reproduces most of the observed phenomenology.

  10. Quantitative DWI implemented after DCE-MRI yields increased specificity for BI-RADS 3 and 4 breast lesions

    NARCIS (Netherlands)

    Dijkstra, Hildebrand; Dorrius, Monique D; Wielema, Mirjam; Pijnappel, Ruud M; Oudkerk, Matthijs; Sijens, Paul E

    2016-01-01

    PURPOSE: To assess if specificity can be increased when semiautomated breast lesion analysis of quantitative diffusion-weighted imaging (DWI) is implemented after dynamic contrast-enhanced (DCE-) magnetic resonance imaging (MRI) in the workup of BI-RADS 3 and 4 breast lesions larger than 1 cm. MATER

  11. Spin Transport and Dynamics in Antiferromagnetic Metals and Magnetic Insulators

    NARCIS (Netherlands)

    Swaving, A.C.|info:eu-repo/dai/nl/313938083

    2012-01-01

    It is demonstrated that in an antiferromagnetic metal a steady-state transport current generates a current-induced out-of-plane spin density, resulting in torques on the magnetization. This spin density is parameterized by a velocity that is proportional to the current. The generalization of the

  12. Critical dynamics of an interacting magnetic nanoparticle system

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Jonsson, P.E.; Nordblad, P.

    2002-01-01

    Effects of dipole-dipole interactions on the magnetic relaxation have been investigated for three Fe-C nanoparticle samples with volume concentrations of 0.06, 5 and 17 vol%. While both the 5 and 17 vol% samples exhibit collective behaviour due to dipolar interactions, only the 17 vol% sample...

  13. The Evolution of Open Magnetic Flux Driven by Photospheric Dynamics

    Science.gov (United States)

    Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav S.; Antiochos, Spiro K.

    2010-01-01

    The coronal magnetic field is of paramount importance in solar and heliospheric physics. Two profoundly different views of the coronal magnetic field have emerged. In quasi-steady models, the predominant source of open magnetic field is in coronal holes. In contrast, in the interchange model, the open magnetic flux is conserved, and the coronal magnetic field can only respond to the photospheric evolution via interchange reconnection. In this view the open magnetic flux diffuses through the closed, streamer belt fields, and substantial open flux is present in the streamer belt during solar minimum. However, Antiochos and co-workers, in the form of a conjecture, argued that truly isolated open flux cannot exist in a configuration with one heliospheric current sheet (HCS) - it will connect via narrow corridors to the polar coronal hole of the same polarity. This contradicts the requirements of the interchange model. We have performed an MHD simulation of the solar corona up to 20R solar to test both the interchange model and the Antiochos conjecture. We use a synoptic map for Carrington Rotation 1913 as the boundary condition for the model, with two small bipoles introduced into the region where a positive polarity extended coronal hole forms. We introduce flows at the photospheric boundary surface to see if open flux associated with the bipoles can be moved into the closed-field region. Interchange reconnection does occur in response to these motions. However, we find that the open magnetic flux cannot be simply injected into closed-field regions - the flux eventually closes down and disconnected flux is created. Flux either opens or closes, as required, to maintain topologically distinct open and closed field regions, with no indiscriminate mixing of the two. The early evolution conforms to the Antiochos conjecture in that a narrow corridor of open flux connects the portion of the coronal hole that is nearly detached by one of the bipoles. In the later evolution, a

  14. Towards wafer scale inductive determination of magnetostatic and dynamic parameters of magnetic thin films and multilayers

    CERN Document Server

    Sievers, Sibylle; Nass, Paul; Serrano-Guisan, Santiago; Pasquale, Massimo; Schumacher, Hans Werner

    2013-01-01

    We investigate an inductive probe head suitable for non-invasive characterization of the magnetostatic and dynamic parameters of magnetic thin films and multilayers on the wafer scale. The probe is based on a planar waveguide with rearward high frequency connectors that can be brought in close contact to the wafer surface. Inductive characterization of the magnetic material is carried out by vector network analyzer ferromagnetic resonance. Analysis of the field dispersion of the resonance allows the determination of key material parameters such as the saturation magnetization MS or the effective damping parameter Meff. Three waveguide designs are tested. The broadband frequency response is characterized and the suitability for inductive determination of MS and Meff is compared. Integration of such probes in a wafer prober could in the future allow wafer scale in-line testing of magnetostatic and dynamic key material parameters of magnetic thin films and multilayers.

  15. Micromagnetic model for studies on Magnetic Tunnel Junction switching dynamics, including local current density

    Energy Technology Data Exchange (ETDEWEB)

    Frankowski, Marek, E-mail: mfrankow@agh.edu.pl; Czapkiewicz, Maciej; Skowronski, Witold; Stobiecki, Tomasz

    2014-02-15

    We present a model introducing the Landau–Lifshitz–Gilbert equation with a Slonczewski's Spin-Transfer-Torque (STT) component in order to take into account spin polarized current influence on the magnetization dynamics, which was developed as an Object Oriented MicroMagnetic Framework extension. We implement the following computations: magnetoresistance of vertical channels is calculated from the local spin arrangement, local current density is used to calculate the in-plane and perpendicular STT components as well as the Oersted field, which is caused by the vertical current flow. The model allows for an analysis of all listed components separately, therefore, the contribution of each physical phenomenon in dynamic behavior of Magnetic Tunnel Junction (MTJ) magnetization is discussed. The simulated switching voltage is compared with the experimental data measured in MTJ nanopillars.

  16. Prospective screening study of 0.5 Tesla dedicated magnetic resonance imaging for the detection of breast cancer in young, high-risk women

    Directory of Open Access Journals (Sweden)

    Sumkin Jules H

    2006-06-01

    Full Text Available Abstract Background Evidence-based screening guidelines are needed for women under 40 with a family history of breast cancer, a BRCA1 or BRCA2 mutation, or other risk factors. An accurate assessment of breast cancer risk is required to balance the benefits and risks of surveillance, yet published studies have used narrow risk assessment schemata for enrollment. Breast density limits the sensitivity of film-screen mammography but is not thought to pose a limitation to MRI, however the utility of MRI surveillance has not been specifically examined before in women with dense breasts. Also, all MRI surveillance studies yet reported have used high strength magnets that may not be practical for dedicated imaging in many breast centers. Medium strength 0.5 Tesla MRI may provide an alternative economic option for surveillance. Methods We conducted a prospective, nonrandomized pilot study of 30 women age 25–49 years with dense breasts evaluating the addition of 0.5 Tesla MRI to conventional screening. All participants had a high quantitative breast cancer risk, defined as ≥ 3.5% over the next 5 years per the Gail or BRCAPRO models, and/or a known BRCA1 or BRCA2 germline mutation. Results The average age at enrollment was 41.4 years and the average 5-year risk was 4.8%. Twenty-two subjects had BIRADS category 1 or 2 breast MRIs (negative or probably benign, whereas no category 4 or 5 MRIs (possibly or probably malignant were observed. Eight subjects had BIRADS 3 results, identifying lesions that were "probably benign", yet prompting further evaluation. One of these subjects was diagnosed with a stage T1aN0M0 invasive ductal carcinoma, and later determined to be a BRCA1 mutation carrier. Conclusion Using medium-strength MRI we were able to detect 1 early breast tumor that was mammographically undetectable among 30 young high-risk women with dense breasts. These results support the concept that breast MRI can enhance surveillance for young high

  17. Assessment of pelvic floor dysfunctions using dynamic magnetic resonance imaging

    Directory of Open Access Journals (Sweden)

    Hoda Salah Darwish

    2014-03-01

    Conclusion: Dynamic MRI is an ideal, non invasive technique which does not require patient preparation for evaluation of pelvic floor. It acts as one stop shop for diagnosing single or multiple pelvic compartment involvement in patients with pelvic floor dysfunction.

  18. XPCS study of dynamic correlation in polyurethane gel-carbonyl iron composite under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Grigoriew, Helena [Institute of Nuclear Chemistry and Technology, Warsaw 03195 (Poland); Wiegart, Lutz [ESRF, Grenoble, 38043 Cedex 9 (France); Boczkowska, Anna [Faculty of Materials Science, Warsaw University of Technology (Poland); Mirkowska, Monika, E-mail: haga311@hotmail.co [Institute of Electronic Materials Technology, Warsaw (Poland)

    2010-10-01

    An X-ray photon correlation spectroscopy (XPCS) study of composite-type material consisting of polyurethane gel and carbonyl iron micrometric spheres was performed under magnetic fields of 0, 300 and 600 mT. The onion-like spheres structure was destroyed during the composite processing. The following conclusions were obtained from the study: -The polyurethane matrix is preferred as a source for the observed dynamic effects. -Below 300mT the material dynamics in direction of the outer magnetic field are very clear. -For 600 mT the dependence of the dynamics on magnetic field direction disappears, but the correlation rate is much higher. These findings may be caused by a disturbance of the polymer mesostructure by larger strain leading to its cross-linking.

  19. Nonequilibrium study of the chiral magnetic effect from real-time simulations with dynamical fermions

    Science.gov (United States)

    Mace, Mark; Mueller, Niklas; Schlichting, Sören; Sharma, Sayantan

    2017-02-01

    We present a real-time lattice approach to study the nonequilibrium dynamics of vector and axial charges in S U (N )×U (1 ) gauge theories. Based on a classical description of the non-Abelian and Abelian gauge fields, we include dynamical fermions and develop operator definitions for (improved) Wilson and overlap fermions that allow us to study real-time manifestations of the axial anomaly from first principles. We present a first application of this approach to anomalous transport phenomena such as the chiral magnetic effect (CME) and the chiral separation effect (CSE) by studying the dynamics of fermions during and after a S U (N ) sphaleron transition in the presence of a U (1 ) magnetic field. We investigate the fermion mass and magnetic field dependence of the suggested signatures of the CME and the CSE and point out some important aspects which need to be accounted for in the macroscopic description of anomalous transport phenomena.

  20. Seismology of the Sun : Inference of Thermal, Dynamic and Magnetic Field Structures of the Interior

    CERN Document Server

    Hiremath, K M

    2012-01-01

    Recent overwhelming evidences show that the sun strongly influences the Earth's climate and environment. Moreover existence of life on this Earth mainly depends upon the sun's energy. Hence, understanding of physics of the sun, especially the thermal, dynamic and magnetic field structures of its interior, is very important. Recently, from the ground and space based observations, it is discovered that sun oscillates near 5 min periodicity in millions of modes. This discovery heralded a new era in solar physics and a separate branch called helioseismology or seismology of the sun has started. Before the advent of helioseismology, sun's thermal structure of the interior was understood from the evolutionary solution of stellar structure equations that mimicked the present age, mass and radius of the sun. Whereas solution of MHD equations yielded internal dynamics and magnetic field structure of the sun's interior. In this presentation, I review the thermal, dynamic and magnetic field structures of the sun's inter...

  1. Generalized Scaling and the Master Variable for Brownian Magnetic Nanoparticle Dynamics.

    Directory of Open Access Journals (Sweden)

    Daniel B Reeves

    Full Text Available Understanding the dynamics of magnetic particles can help to advance several biomedical nanotechnologies. Previously, scaling relationships have been used in magnetic spectroscopy of nanoparticle Brownian motion (MSB to measure biologically relevant properties (e.g., temperature, viscosity, bound state surrounding nanoparticles in vivo. Those scaling relationships can be generalized with the introduction of a master variable found from non-dimensionalizing the dynamical Langevin equation. The variable encapsulates the dynamical variables of the surroundings and additionally includes the particles' size distribution and moment and the applied field's amplitude and frequency. From an applied perspective, the master variable allows tuning to an optimal MSB biosensing sensitivity range by manipulating both frequency and field amplitude. Calculation of magnetization harmonics in an oscillating applied field is also possible with an approximate closed-form solution in terms of the master variable and a single free parameter.

  2. 乳腺核磁共振成像恶性肿瘤征象的META分析%Meta Analysis On Magnetic Resonance Imaging Signs For Breast Cancer

    Institute of Scientific and Technical Information of China (English)

    石宇文

    2015-01-01

    Objective The purpose of this study is to meta-analysis the diagnostic value of breast magnetic resonance imaging (MRI) of various malignancies signs. Methods Using Meta-Disc 1.4 software, diagnostic effectiveness of every MRI diagnosis signs was evaluated one by one. Results In accordance with the inclusion and exclusion criteria, 19 independent studies eventually included in this Meta-analysis. Meta-analysis showed that: ① burr-like shape AUC value of 0.8167, Q value of 0.7506. ②blurred edges AUC value of 0.6881, Q value of 0.6435. ③ ring enhancement AUC value of 0.6879, Q value of 0.6433. ④washout curve AUC value of 0.7955, Q value of 0.7320. ⑤ADC measurement AUC value of 0.5610, Q value of 0.5459. Using a random effects model merge MRI diagnosis of breast cancer overall sensitivity was 0.497, specificity was 0.810, AUC value of 0.7071, Q value of 0.6585. Conclusion Various malignancies signs of breast magnetic resonance imaging (MRI) provide different effectiveness for diagnosis, burr-like morphology and dynamic contrast-enhanced washout curve signs have higher diagnostic predictive value for breast cancer, while the diagnostic value of measuring ring enhancement and ADC values are poor.%目的:本研究的目的是荟萃分析乳腺核磁共振成像(MRI)的各个恶性肿瘤征象,为MR诊断及鉴别诊断乳腺肿瘤性质提供依据。方法文献检索查找乳腺核磁共振成像的各个恶性征象提示,并经由病理确诊的乳腺恶性肿瘤的试验,采用Meta-Disc 1.4软件,对各个MRI恶性征象的诊断效能进行逐一评价。结果按照文献纳入及排除标准最终有19项独立研究纳入本次Meta分析。Meta分析结果显示:①毛刺状形态AUC值为0.8167, Q值0.7506。②边缘模糊不清AUC值为0.6881,Q值0.6435。③环状强化AUC值为0.6879,Q值0.6433。④washout曲线AUC值为0.7955,Q值0.7320。⑤ADC值测量AUC值为0.5610,Q值0.5459。采用随机效应

  3. Magnetic correlation, excitation and slow dynamics in concentrated spin-glass alloys

    Indian Academy of Sciences (India)

    Kiyoichiro Motoya

    2004-07-01

    Three kinds of neutron scattering experiments have been performed to clarify the role of magnetic clusters on the various properties of re-entrant spin-glasses. The presence of two kinds of spin-wave excitations, the limitations of magnetic phase diagrams and the mechanism of slow dynamics have been discussed based on the results of in-elastic scattering, diffuse scattering and time-resolved small-angle scattering experiments, respectively.

  4. A Laboratory Plasma Experiment for Studying Magnetic Dynamics of Accretion Discs and Jets

    OpenAIRE

    Hsu, S. C.; Bellan, P. M.

    2002-01-01

    This work describes a laboratory plasma experiment and initial results which should give insight into the magnetic dynamics of accretion discs and jets. A high-speed multiple-frame CCD camera reveals images of the formation and helical instability of a collimated plasma, similar to MHD models of disc jets, and also plasma detachment associated with spheromak formation, which may have relevance to disc winds and flares. The plasmas are produced by a planar magnetized coaxial gun. The resulting...

  5. Asymmetric driven dynamics of Dzyaloshinskii domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Tejerina, L. [Dpto. Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain); Alejos, Ó., E-mail: oscaral@ee.uva.es [Dpto. Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain); Martínez, E. [Dpto. Física Aplicada, Facultad de Ciencias, Universidad de Salamanca, 37011 Salamanca (Spain); Muñoz, J.M. [Dpto. Electricidad y Electrónica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain)

    2016-07-01

    The dynamics of domain walls in ultrathin ferromagnetic strips with perpendicular magnetic anisotropy is studied from both numerical and analytical micromagnetics. The influence of a moderate interfacial Dzyaloshinskii–Moriya interaction associated to a bi-layer strip arrangement has been considered, giving rise to the formation of Dzyaloshinskii domain walls. Such walls possess under equilibrium conditions an inner magnetization structure defined by a certain orientation angle that make them to be considered as intermediate configurations between Bloch and Néel walls. Two different dynamics are considered, a field-driven and a current-driven dynamics, in particular, the one promoted by the spin torque due to the spin-Hall effect. Results show an inherent asymmetry associated with the rotation of the domain wall magnetization orientation before reaching the stationary regime, characterized by a constant terminal speed. For a certain initial DW magnetization orientation at rest, the rotation determines whether the reorientation of the DW magnetization prior to reach stationary motion is smooth or abrupt. This asymmetry affects the DW motion, which can even reverse for a short period of time. Additionally, it is found that the terminal speed in the case of the current-driven dynamics may depend on either the initial DW magnetization orientation at rest or the sign of the longitudinally injected current. - Highlights: • The asymmetric response of domain walls in bilayer strips with PMA is studied. • Out-of-plane fields and SHE longitudinal currents are applied. • The response is associated to the rotation of the domain wall inner magnetization. • Clockwise and counter-clockwise magnetization rotations are not equivalent. • The asymmetry results in different travelled distances and/or terminal speeds.

  6. The negative predictive value of breast Magnetic Resonance Imaging in noncalcified BIRADS 3 lesions

    NARCIS (Netherlands)

    Dorrius, M. D.; Pijnappel, R. M.; Sijens, P. E.; van der Weide, M. C. Jansen; Oudkerk, M.

    2012-01-01

    Purpose: The purpose of this study is to determine whether breast MRI can provide a sufficient NPV to safely rule out malignancy in mammographic BIRADS 3 lesions. Materials and methods: In a 3-year consecutive mammographic examination study 176 out of 4391 patients had a lesion classified as BIRADS

  7. Photoacoustic image patterns of breast carcinoma and comparisons with Magnetic Resonance Imaging and vascular stained histopathology.

    Science.gov (United States)