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Sample records for astrocytoma identifies robust

  1. DNA methylation analysis of paediatric low-grade astrocytomas identifies a tumour-specific hypomethylation signature in pilocytic astrocytomas.

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    Jeyapalan, Jennie N; Doctor, Gabriel T; Jones, Tania A; Alberman, Samuel N; Tep, Alexander; Haria, Chirag M; Schwalbe, Edward C; Morley, Isabel C F; Hill, Alfred A; LeCain, Magdalena; Ottaviani, Diego; Clifford, Steven C; Qaddoumi, Ibrahim; Tatevossian, Ruth G; Ellison, David W; Sheer, Denise

    2016-05-27

    Low-grade gliomas (LGGs) account for about a third of all brain tumours in children. We conducted a detailed study of DNA methylation and gene expression to improve our understanding of the biology of pilocytic and diffuse astrocytomas. Pilocytic astrocytomas were found to have a distinctive signature at 315 CpG sites, of which 312 were hypomethylated and 3 were hypermethylated. Genomic analysis revealed that 182 of these sites are within annotated enhancers. The signature was not present in diffuse astrocytomas, or in published profiles of other brain tumours and normal brain tissue. The AP-1 transcription factor was predicted to bind within 200 bp of a subset of the 315 differentially methylated CpG sites; the AP-1 factors, FOS and FOSL1 were found to be up-regulated in pilocytic astrocytomas. We also analysed splice variants of the AP-1 target gene, CCND1, which encodes cell cycle regulator cyclin D1. CCND1a was found to be highly expressed in both pilocytic and diffuse astrocytomas, but diffuse astrocytomas have far higher expression of the oncogenic variant, CCND1b. These findings highlight novel genetic and epigenetic differences between pilocytic and diffuse astrocytoma, in addition to well-described alterations involving BRAF, MYB and FGFR1.

  2. Pilocytic astrocytoma

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    Yu-wei CONG

    2015-03-01

    Full Text Available Background Pilocytic astrocytoma (PA is a low-grade glioma that occurs mainly in children and young adults. The histomorphology of PA located in the cerebellum (WHOⅠ is very typical. This article is to report one case of PA in the cerebellum of an 8-year-old child, and to discuss the clinical, imaging and pathological features of PA and clinicopathological differentiations from relevant tumors.  Methods and Results An 8-year-old girl presented intermittent headache for one month and the headache was aggravated for 7 d. MRI showed circular space-occupying lesion in the left cerebellar hemisphere and cerebellar vermis, and the lesion revealed uneven signals. During the surgery, the tumor was soft and jellylike, with poor blood supply. Histologically, tumor cell nuclei were round or oval; cytoplasmic projections on both ends were slender hair-like, and were arranged around the blood vessels. Part of tumor cells had spindle nuclei, and showed fascicular compact arrangement or loose reticular arrangement. The pathomorphism of this tumro was slightly different from that of typical PA. It had unusually rich blood vessels, and Rosenthal fibers and eosinophilic granules were not obvious. Tumor cells were diffusely positive for glial fibrillary acidic protein (GFAP, synaptophysin (Syn, vimentin (Vim and P53, but negative for cytokeratin (CK, neuronal nuclei (NeuN and neurofilament protein (NF. Ki-67 index was 2%-5%. Vascular endothelial cells were positive for CD34, and scatteredly expressed CD68. Pathological diagosis was pilocytic astrocytoma (WHOⅠ.  Conclusions Pilocytic astrocytoma usually happens in children and adolescents and often occurs in the cerebellum. Rosenthal fibers and eosinophilic granules are helpful to make a clear diagnosis, but they are not necessary conditions of diagnosis. Differential diagnoses should be paid attention, such as pilomyxoid astrocytoma, angiocentric glioma and dysembryoplastic neuroepithelial tumor (DNT

  3. Molecular analysis of pediatric brain tumors identifies microRNAs in pilocytic astrocytomas that target the MAPK and NF-κB pathways.

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    Jones, Tania A; Jeyapalan, Jennie N; Forshew, Tim; Tatevossian, Ruth G; Lawson, Andrew R J; Patel, Sheena N; Doctor, Gabriel T; Mumin, Muhammad A; Picker, Simon R; Phipps, Kim P; Michalski, Antony; Jacques, Thomas S; Sheer, Denise

    2015-12-18

    Pilocytic astrocytomas are slow-growing tumors that usually occur in the cerebellum or in the midline along the hypothalamic/optic pathways. The most common genetic alterations in pilocytic astrocytomas activate the ERK/MAPK signal transduction pathway, which is a major driver of proliferation but is also believed to induce senescence in these tumors. Here, we have conducted a detailed investigation of microRNA and gene expression, together with pathway analysis, to improve our understanding of the regulatory mechanisms in pilocytic astrocytomas. Pilocytic astrocytomas were found to have distinctive microRNA and gene expression profiles compared to normal brain tissue and a selection of other pediatric brain tumors. Several microRNAs found to be up-regulated in pilocytic astrocytomas are predicted to target the ERK/MAPK and NF-κB signaling pathways as well as genes involved in senescence-associated inflammation and cell cycle control. Furthermore, IGFBP7 and CEBPB, which are transcriptional inducers of the senescence-associated secretory phenotype (SASP), were also up-regulated together with the markers of senescence and inflammation, CDKN1A (p21), CDKN2A (p16) and IL1B. These findings provide further evidence of a senescent phenotype in pilocytic astrocytomas. In addition, they suggest that the ERK/MAPK pathway, which is considered the major driver of these tumors, is regulated not only by genetic aberrations but also by microRNAs.

  4. Prognosis and Treatment of Spinal Cord Astrocytoma

    International Nuclear Information System (INIS)

    Minehan, Kiernan J.; Brown, Paul D.; Scheithauer, Bernd W.; Krauss, William E.; Wright, Michael P.

    2009-01-01

    Purpose: To identify the prognostic factors for spinal cord astrocytoma and determine the effects of surgery and radiotherapy on outcome. Methods and Materials: This retrospective study reviewed the cases of consecutive patients with spinal cord astrocytoma treated at Mayo Clinic Rochester between 1962 and 2005. Results: A total of 136 consecutive patients were identified. Of these 136 patients, 69 had pilocytic and 67 had infiltrative astrocytoma. The median follow-up for living patients was 8.2 years (range, 0.08-37.6), and the median survival for deceased patients was 1.15 years (range, 0.01-39.9). The extent of surgery included incisional biopsy only (59%), subtotal resection (25%), and gross total resection (16%). Patients with pilocytic tumors survived significantly longer than those with infiltrative astrocytomas (median overall survival, 39.9 vs. 1.85 years; p < 0.001). Patients who underwent resection had a worse, although nonsignificant, median survival than those who underwent biopsy only (pilocytic, 18.1 vs. 39.9 years, p = 0.07; infiltrative, 19 vs. 30 months, p = 0.14). Postoperative radiotherapy, delivered in 75% of cases, gave no significant survival benefit for those with pilocytic tumors (39.9 vs. 18.1 years, p = 0.33) but did for those with infiltrative astrocytomas (24 vs. 3 months; Wilcoxon p = 0.006). On multivariate analysis, pilocytic histologic type, diagnosis after 1984, longer symptom duration, younger age, minimal surgical extent, and postoperative radiotherapy predicted better outcome. Conclusion: The results of our study have shown that histologic type is the most important prognostic variable affecting the outcome of spinal cord astrocytomas. Surgical resection was associated with shorter survival and thus remains an unproven treatment. Postoperative radiotherapy significantly improved survival for patients with infiltrative astrocytomas but not for those with pilocytic tumors

  5. Prognostic parameters in benign astrocytomas

    DEFF Research Database (Denmark)

    Westergaard, L; Gjerris, F; Klinken, L

    1993-01-01

    astrocytomas treated in the period 1956 to 1991. The pilocytic type of astrocytoma was found to have an outstandingly good prognosis and should be regarded as a distinct nosological entity. For the non-pilocytic supratentorial astrocytomas, a multivariate regression analysis showed that age, tumour site...

  6. Robust modal curvature features for identifying multiple damage in beams

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    Ostachowicz, Wiesław; Xu, Wei; Bai, Runbo; Radzieński, Maciej; Cao, Maosen

    2014-03-01

    Curvature mode shape is an effective feature for damage detection in beams. However, it is susceptible to measurement noise, easily impairing its advantage of sensitivity to damage. To deal with this deficiency, this study formulates an improved curvature mode shape for multiple damage detection in beams based on integrating a wavelet transform (WT) and a Teager energy operator (TEO). The improved curvature mode shape, termed the WT - TEO curvature mode shape, has inherent capabilities of immunity to noise and sensitivity to damage. The proposed method is experimentally validated by identifying multiple cracks in cantilever steel beams with the mode shapes acquired using a scanning laser vibrometer. The results demonstrate that the improved curvature mode shape can identify multiple damage accurately and reliably, and it is fairly robust to measurement noise.

  7. Integrated analysis of mismatch repair system in malignant astrocytomas.

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    Irene Rodríguez-Hernández

    Full Text Available Malignant astrocytomas are the most aggressive primary brain tumors with a poor prognosis despite optimal treatment. Dysfunction of mismatch repair (MMR system accelerates the accumulation of mutations throughout the genome causing uncontrolled cell growth. The aim of this study was to characterize the MMR system defects that could be involved in malignant astrocytoma pathogenesis. We analyzed protein expression and promoter methylation of MLH1, MSH2 and MSH6 as well as microsatellite instability (MSI and MMR gene mutations in a set of 96 low- and high-grade astrocytomas. Forty-one astrocytomas failed to express at least one MMR protein. Loss of MSH2 expression was more frequent in low-grade astrocytomas. Loss of MLH1 expression was associated with MLH1 promoter hypermethylation and MLH1-93G>A promoter polymorphism. However, MSI was not related with MMR protein expression and only 5% of tumors were MSI-High. Furthermore, the incidence of tumors carrying germline mutations in MMR genes was low and only one glioblastoma was associated with Lynch syndrome. Interestingly, survival analysis identified that tumors lacking MSH6 expression presented longer overall survival in high-grade astrocytoma patients treated only with radiotherapy while MSH6 expression did not modify the prognosis of those patients treated with both radiotherapy and chemotherapy. Our findings suggest that MMR system alterations are a frequent event in malignant astrocytomas and might help to define a subgroup of patients with different outcome.

  8. Nitroproteins in Human Astrocytomas Discovered by Gel Electrophoresis and Tandem Mass Spectrometry

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    Peng, Fang; Li, Jianglin; Guo, Tianyao; Yang, Haiyan; Li, Maoyu; Sang, Shushan; Li, Xuejun; Desiderio, Dominic M.; Zhan, Xianquan

    2015-12-01

    Protein tyrosine nitration is involved in the pathogenesis of highly fatal astrocytomas, a type of brain cancer. To understand the molecular mechanisms of astrocytomas and to discover new biomarkers/therapeutic targets, we sought to identify nitroproteins in human astrocytoma tissue. Anti-nitrotyrosine immunoreaction-positive proteins from a high-grade astrocytoma tissue were detected with two-dimensional gel electrophoresis (2DGE)-based nitrotyrosine immunoblots, and identified with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Fifty-seven nitrotyrosine immunopositive protein spots were detected. A total of 870 proteins (nitrated and non-nitrated) in nitrotyrosine-immunopositive 2D gel spots were identified, and 18 nitroproteins and their 20 nitrotyrosine sites were identified with MS/MS analysis. These nitroproteins participate in multiple processes, including drug-resistance, signal transduction, cytoskeleton, transcription and translation, cell proliferation and apoptosis, immune response, phenotypic dedifferentiation, cell migration, and metastasis. Among those nitroproteins that might play a role in astrocytomas was nitro-sorcin, which is involved in drug resistance and metastasis and might play a role in the spread and treatment of an astrocytoma. Semiquantitative immune-based measurements of different sorcin expressions were found among different grades of astrocytomas relative to controls, and a semiquantitative increased nitration level in high-grade astrocytoma relative to control. Nitro-β-tubulin functions in cytoskeleton and cell migration. Semiquantitative immunoreactivity of β-tubulin showed increased expression among different grades of astrocytomas relative to controls and semiquantitatively increased nitration level in high-grade astrocytoma relative to control. Each nitroprotein was rationalized and related to the corresponding functional system to provide new insights into tyrosine nitration and its potential role in the

  9. Safe Exploration for Identifying Linear Systems via Robust Optimization

    OpenAIRE

    Lu, Tyler; Zinkevich, Martin; Boutilier, Craig; Roy, Binz; Schuurmans, Dale

    2017-01-01

    Safely exploring an unknown dynamical system is critical to the deployment of reinforcement learning (RL) in physical systems where failures may have catastrophic consequences. In scenarios where one knows little about the dynamics, diverse transition data covering relevant regions of state-action space is needed to apply either model-based or model-free RL. Motivated by the cooling of Google's data centers, we study how one can safely identify the parameters of a system model with a desired ...

  10. The molecular biology of WHO grade I astrocytomas.

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    Marko, Nicholas F; Weil, Robert J

    2012-12-01

    World Health Organization (WHO) grade I astrocytomas include pilocytic astrocytoma (PA) and subependymal giant cell astrocytoma (SEGA). As technologies in pharmacologic neo-adjuvant therapy continue to progress and as molecular characteristics are progressively recognized as potential markers of both clinically significant tumor subtypes and response to therapy, interest in the biology of these tumors has surged. An updated review of the current knowledge of the molecular biology of these tumors is needed. We conducted a Medline search to identify published literature discussing the molecular biology of grade I astrocytomas. We then summarized this literature and discuss it in a logical framework through which the complex biology of these tumors can be clearly understood. A comprehensive review of the molecular biology of WHO grade I astrocytomas is presented. The past several years have seen rapid progress in the level of understanding of PA in particular, but the molecular literature regarding both PA and SEGA remains nebulous, ambiguous, and occasionally contradictory. In this review we provide a comprehensive discussion of the current understanding of the chromosomal, genomic, and epigenomic features of both PA and SEGA and provide a logical framework in which these data can be more readily understood.

  11. Retinal astrocytoma in a dog.

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    Kuroki, Keiichi; Kice, Nathan; Ota-Kuroki, Juri

    2017-09-01

    A miniature schnauzer dog presenting with hyphema and glaucoma of the right eye had a retinal neoplasm. Neoplastic cells stained positively for glial fibrillary acidic protein, vimentin, and S-100 and largely negatively for oligodendrocyte transcription factor 2 by immunohistochemistry. The clinical and histopathological features of canine retinal astrocytomas are discussed.

  12. Identification of astrocytoma associated genes including cell surface markers

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    Boon, Kathy; Edwards, Jennifer B; Eberhart, Charles G; Riggins, Gregory J

    2004-01-01

    Despite intense effort the treatment options for the invasive astrocytic tumors are still limited to surgery and radiation therapy, with chemotherapy showing little or no increase in survival. The generation of Serial Analysis of Gene Expression (SAGE) profiles is expected to aid in the identification of astrocytoma-associated genes and highly expressed cell surface genes as molecular therapeutic targets. SAGE tag counts can be easily added to public expression databases and quickly disseminated to research efforts worldwide. We generated and analyzed the SAGE transcription profiles of 25 primary grade II, III and IV astrocytomas [1]. These profiles were produced as part of the Cancer Genome Anatomy Project's SAGE Genie [2], and were used in an in silico search for candidate therapeutic targets by comparing astrocytoma to normal brain transcription. Real-time PCR and immunohistochemistry were used for the validation of selected candidate target genes in 2 independent sets of primary tumors. A restricted set of tumor-associated genes was identified for each grade that included genes not previously associated with astrocytomas (e.g. VCAM1, SMOC1, and thymidylate synthetase), with a high percentage of cell surface genes. Two genes with available antibodies, Aquaporin 1 and Topoisomerase 2A, showed protein expression consistent with transcript level predictions. This survey of transcription in malignant and normal brain tissues reveals a small subset of human genes that are activated in malignant astrocytomas. In addition to providing insights into pathway biology, we have revealed and quantified expression for a significant portion of cell surface and extra-cellular astrocytoma genes

  13. Spontaneous anaplasia in pilocytic astrocytoma of cerebellum.

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    Lach, B; Al Shail, E; Patay, Z

    2003-06-01

    We report a cystic cerebellar astrocytoma with a mural nodule that contained an additional focus of astrocytoma with the histological features of anaplasia, and showed up to 48% of aneuploid and 3% S-phase cells on flow cytometry. This focus was detectable on the enhanced, as well as non-enhanced T1 and T2 images. This appears to be the first case of pilocytic astrocytoma of cerebellum with focal anaplasia detected on histological and radiological studies.

  14. RTEL1 and TERT polymorphisms are associated with astrocytoma risk in the Chinese Han population.

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    Jin, Tian-Bo; Zhang, Jia-Yi; Li, Gang; Du, Shu-Li; Geng, Ting-Ting; Gao, Jing; Liu, Qian-Ping; Gao, Guo-Dong; Kang, Long-Li; Chen, Chao; Li, Shan-Qu

    2013-12-01

    Common variants of multiple genes play a role in glioma onset. However, research related to astrocytoma, the most common primary brain neoplasm, is rare. In this study, we chose 21 tagging SNPs (tSNPs), previously reported to be associated with glioma risk in a Chinese case-control study from Xi'an, China, and identified their contributions to astrocytoma susceptibility. We found an association with astrocytoma susceptibility for two tSNPs (rs6010620 and rs2853676) in two different genes: regulator of telomere elongation helicase 1 (RTEL1) and telomerase reverse transcriptase (TERT), respectively. We confirmed our results using recessive, dominant, and additive models. In the recessive model, we found two tSNPs (rs2297440 and rs6010620) associated with increased astrocytoma risk. In the dominant model, we found that rs2853676 was associated with increased astrocytoma risk. In the additive model, all three tSNPs (rs2297440, rs2853676, and rs6010620) were associated with increased astrocytoma risk. Our results demonstrate, for the first time, the potential roles of RTEL1 and TERT in astrocytoma development.

  15. Robust

    DEFF Research Database (Denmark)

    2017-01-01

    Robust – Reflections on Resilient Architecture’, is a scientific publication following the conference of the same name in November of 2017. Researches and PhD-Fellows, associated with the Masters programme: Cultural Heritage, Transformation and Restoration (Transformation), at The Royal Danish...

  16. Postradiation astrocytoma. Report of two cases

    International Nuclear Information System (INIS)

    Kitanaka, C.; Shitara, N.; Nakagomi, T.; Nakamura, H.; Genka, S.; Nakagawa, K.; Akanuma, A.; Aoyama, H.; Takakura, K.

    1989-01-01

    The authors describe two cases of malignant astrocytomas associated with previous radiation therapy in childhood for intracranial germinoma and craniopharyngioma. In both patients, there was no recurrence at the primary tumor site. Because of a geometric coincidence between the tumor location and the radiation field, radiotherapy was strongly implicated as a cause of these two astrocytomas.33 references

  17. Imaging characteristics of pilomyxoid astrocytomas in comparison with pilocytic astrocytomas

    International Nuclear Information System (INIS)

    Lee, In Ho; Kim, Ji Hye; Suh, Yeon-Lim; Eo, Hong; Shin, Hyung Jin; Yoo, So-Young; Lee, Kyung Soo

    2011-01-01

    Purpose: Pilomyxoid astrocytoma (PMA) is a recently described astrocytic tumor that has been previously diagnosed as pilocytic astrocytoma (PA). The purpose of this study was to describe the imaging features of PMAs in comparison with PAs. Materials and methods: We retrospectively reviewed CT/MR images and medical records of 10 patients with PMA and 38 patients with PA. The mean ages of patients with PMA and PA were 10 and 15 years, respectively. Imaging features including location, composition, enhancement pattern, presence of calcification, hemorrhage, and leptomeningeal dissemination were compared in patients with two tumor types. Results: Six PMAs (60%) occurred at the suprasellar area and the cerebellum was the most common (45%) site of PA. Solid component was dominant in eight PMAs (80%) and in 19 PAs (50%). All of the PMAs containing solid mass (n = 8) included non-enhancing portion while 12/37 (32%) PAs included non-enhancing solid portion (p < 0.05). Leptomeningeal dissemination was noted in five PMAs (50%) and one PA (3%) (p < 0.05). Other imaging findings were not significantly different. Conclusion: A younger age, more frequent occurrence at the suprasellar area, mainly solid mass containing non-enhancing portion, and more frequent leptomeningeal dissemination are helpful differential features of PMAs as compared to PAs.

  18. Neurotrophin receptors expression and JNK pathway activation in human astrocytomas

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    Maraziotis Theodore

    2007-10-01

    Full Text Available Abstract Background Neurotrophins are growth factors that regulate cell growth, differentiation and apoptosis in the nervous system. Their diverse actions are mediated through two different transmembrane – receptor signaling systems: Trk receptor tyrosine kinases (TrkA, TrkB, TrkC and p75NTR neurotrophin receptor. Trk receptors promote cell survival and differentiation while p75NTR induces, in most cases, the activity of JNK-p53-Bax apoptosis pathway or suppresses intracellular survival signaling cascades. Robust Trk activation blocks p75NTR -induced apoptosis by suppressing the JNK-p53-Bax pathway. The aim of this exploratory study was to investigate the expression levels of neurotrophin receptors, Trks and p75NTR, and the activation of JNK pathway in human astrocytomas and in adjacent non-neoplastic brain tissue. Methods Formalin-fixed paraffin-embedded serial sections from 33 supratentorial astrocytomas (5 diffuse fibrillary astrocytomas, WHO grade II; 6 anaplastic astrocytomas, WHO grade III; 22 glioblastomas multiforme, WHO grade IV were immunostained following microwave pretreatment. Polyclonal antibodies against TrkA, TrkB, TrkC and monoclonal antibodies against p75NTR and phosphorylated forms of JNK (pJNK and c-Jun (pc-Jun were used. The labeling index (LI, defined as the percentage of positive (labeled cells out of the total number of tumor cells counted, was determined. Results Moderate to strong, granular cytoplasmic immunoreactivity for TrkA, TrkB and TrkC receptors was detected in greater than or equal to 10% of tumor cells in the majority of tumors independently of grade; on the contrary, p75NTR receptor expression was found in a small percentage of tumor cells (~1% in some tumors. The endothelium of tumor capillaries showed conspicuous immunoreactivity for TrkB receptor. Trk immunoreactivity seemed to be localized in some neurons and astrocytes in non-neoplastic tissue. Phosphorylated forms of JNK (pJNK and c-Jun (pc-Jun were

  19. Neurotrophin receptors expression and JNK pathway activation in human astrocytomas

    International Nuclear Information System (INIS)

    Assimakopoulou, Martha; Kondyli, Maria; Gatzounis, George; Maraziotis, Theodore; Varakis, John

    2007-01-01

    Neurotrophins are growth factors that regulate cell growth, differentiation and apoptosis in the nervous system. Their diverse actions are mediated through two different transmembrane – receptor signaling systems: Trk receptor tyrosine kinases (TrkA, TrkB, TrkC) and p75 NTR neurotrophin receptor. Trk receptors promote cell survival and differentiation while p75 NTR induces, in most cases, the activity of JNK-p53-Bax apoptosis pathway or suppresses intracellular survival signaling cascades. Robust Trk activation blocks p75 NTR -induced apoptosis by suppressing the JNK-p53-Bax pathway. The aim of this exploratory study was to investigate the expression levels of neurotrophin receptors, Trks and p75 NTR , and the activation of JNK pathway in human astrocytomas and in adjacent non-neoplastic brain tissue. Formalin-fixed paraffin-embedded serial sections from 33 supratentorial astrocytomas (5 diffuse fibrillary astrocytomas, WHO grade II; 6 anaplastic astrocytomas, WHO grade III; 22 glioblastomas multiforme, WHO grade IV) were immunostained following microwave pretreatment. Polyclonal antibodies against TrkA, TrkB, TrkC and monoclonal antibodies against p75 NTR and phosphorylated forms of JNK (pJNK) and c-Jun (pc-Jun) were used. The labeling index (LI), defined as the percentage of positive (labeled) cells out of the total number of tumor cells counted, was determined. Moderate to strong, granular cytoplasmic immunoreactivity for TrkA, TrkB and TrkC receptors was detected in greater than or equal to 10% of tumor cells in the majority of tumors independently of grade; on the contrary, p75 NTR receptor expression was found in a small percentage of tumor cells (~1%) in some tumors. The endothelium of tumor capillaries showed conspicuous immunoreactivity for TrkB receptor. Trk immunoreactivity seemed to be localized in some neurons and astrocytes in non-neoplastic tissue. Phosphorylated forms of JNK (pJNK) and c-Jun (pc-Jun) were significantly co-expressed in a tumor

  20. astrocytoma – diagnostic pitfalls. A review

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    Ewa Matyja

    2016-10-01

    Full Text Available Pilocytic astrocytomas (PAs are the most frequent primary astroglial tumours affecting children and adolescents. They occur sporadically or in association with a genetically determined syndrome – neurofibromatosis type 1. Classic PA usually manifests as a well-circumscribed, often cystic, slowly growing tumour, which corresponds to WHO grade I. The majority of pilocytic tumours arise along the neuraxis, predominantly in the cerebellum. They are associated with favourable long-term outcome or spontaneous regression, even after incomplete resection. However, the behaviour and prognosis might also be related to tumour histology and location. Pilomyxoid astrocytoma (PMA represents a variant of classical PA with more invasive growth and increased risk of recurrences and dissemination. Typically, PAs exhibit distinct histology with biphasic architecture of loose, microcystic and compact, fibrillary areas. However, some tumours arise in an uncommon location and display heterogeneous histopathological appearance. The morphological pattern of PA can mimic some other glial neoplasms, including oligodendroglioma, pleomorphic xanthoastrocytoma, ependymoma or diffuse astrocytoma. Not infrequently, the advanced degenerative changes, including vascular fibrosis, and recent and old haemorrhages, may mimic vascular pathology. Sometimes, the neoplastic piloid tissue can resemble reactive gliosis, related to long-standing non neoplastic lesions. Not infrequently, PA exhibits histological features typical for anaplasia, including necrosis, mitoses and glomeruloid vascular proliferation that can suggest a diffuse high-grade glioma. However, even those PAs that lack distinct histological features of anaplasia can behave unpredictably, in a more aggressive manner, with leptomeningeal spreading. Genetic alterations resulting in aberrant signalling of the mitogen-activated protein kinase (MAPK pathway have been considered to underlie the development of PAs. The most

  1. Adult Pilomyxoid Astrocytoma Mimicking a Cortical Brain Tumor: MR Imaging Findings

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jong Chang; Weon, Young Cheol; Suh, Jae Hee; Kim, Young; Hwang, Jae Cheol [Ulsan University Hospital, Ulsan (Korea, Republic of)

    2010-08-15

    A pilomyxoid astrocytoma (PMA) is a recently identified low-grade neoplasm that was previously classified as a pilocytic astrocytoma (PA), yet demonstrates unique histological features and more aggressive behavior. Although a PMA is generally a tumor of early childhood and typically occurs in the hypothalamic/chiasmatic region, it can mimic cortical tumors, especially in adults. We report the MR findings of a PMA presenting as a cortical brain tumor in an adult with neurofibromatosis 1 (NF1)

  2. Robust Nonnegative Matrix Factorization via Joint Graph Laplacian and Discriminative Information for Identifying Differentially Expressed Genes

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    Ling-Yun Dai

    2017-01-01

    Full Text Available Differential expression plays an important role in cancer diagnosis and classification. In recent years, many methods have been used to identify differentially expressed genes. However, the recognition rate and reliability of gene selection still need to be improved. In this paper, a novel constrained method named robust nonnegative matrix factorization via joint graph Laplacian and discriminative information (GLD-RNMF is proposed for identifying differentially expressed genes, in which manifold learning and the discriminative label information are incorporated into the traditional nonnegative matrix factorization model to train the objective matrix. Specifically, L2,1-norm minimization is enforced on both the error function and the regularization term which is robust to outliers and noise in gene data. Furthermore, the multiplicative update rules and the details of convergence proof are shown for the new model. The experimental results on two publicly available cancer datasets demonstrate that GLD-RNMF is an effective method for identifying differentially expressed genes.

  3. Cerebral hemisphere astrocytoma: Treatment results

    International Nuclear Information System (INIS)

    Boyages, J.; Tiver, K.W.

    1987-01-01

    Eighty two adult patients with histologically proven cerebral astrocytomas of grades I to IV received post-operative radiotherapy at Westmead Hospital between January 1980 and February 1985. Seventy one patients completed a course of megavoltage irradiation, the majority having received a tumour dose of at least 60 Gy. Patients who underwent surgical resection had a greater median survival than those undergoing biopsy, but the difference was not statistically significant. By grade, the difference reached statistical significance only for grade III tumours. Patients with high grade tumours had a significantly lower survival than those patients with tumours of low grade. After adjustment for grade, various dosage levels did not significantly affect survival, although there was a trend towards improved median survival with higher doses in grade III tumours. When included in a multivariate analysis, the extent of surgery did not significantly influence survival, but increasing tumour grade and increasing age were significant adverse prognostic factors. (Auth.)

  4. [Diagnostic imaging of high-grade astrocytoma: heterogeneity of clinical manifestation, image characteristics, and histopathological findings].

    Science.gov (United States)

    Okajima, Kaoru; Ohta, Yoshio

    2012-10-01

    Recent developments in diagnostic radiology, which have enabled accurate differential diagnoses of brain tumors, have been well described in the last three decades. MR and PET imaging can also provide information to predict histological grades and prognoses that might influence treatment strategies. However, high-grade astrocytomas consist of many different subtypes that are associated with different imaging and histological characteristics. Hemorrhage and necrosis results in a variety of imaging features, and infiltrative tumor growth entrapping normal neurons may cause different clinical manifestations. We reviewed patients with high-grade astrocytomas that showed various imaging characteristics, with special emphasis on initial symptoms and histological features. Clinicopathological characteristics of astrocytomas were also compared with other malignant tumors. Neurological deficits were not notable in patients with grade 3-4 astrocytomas when they showed infiltrative tumor growth, while brain metastases with compact cellular proliferation caused more neurological symptoms. Infiltrative tumors did not show any enhancing masses on MR imaging, but these tumors may show intratumor heterogeneity. Seizures were reported to be more frequent in low-grade glioma and in secondary glioblastoma. Tumor heterogeneity was also reported in molecular genetic profile, and investigators identified some subsets of astrocytomas. They investigated IHD1/2 mutation, EGFR amplification, TP53 mutation, Ki-67 index, etc. In summary, high-grade astrocytomas are not homogenous groups of tumors, and this is associated with the heterogeneity of clinical manifestation, image characteristics, and histopathological findings. Molecular studies may explain the tumor heterogeneity in the near future.

  5. MR imaging characteristics of protoplasmic astrocytomas

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    Tay, Kevin L. [Royal Melbourne Hospital, Department of Radiology, Parkville, Victoria (Australia); Royal North Shore Hospital, Department of Radiology, St Leonards, New South Wales (Australia); Tsui, Alpha [Royal Melbourne Hospital, Department of Pathology, Parkville, Victoria (Australia); Phal, Pramit M.; Tress, Brian M. [Royal Melbourne Hospital, Department of Radiology, Parkville, Victoria (Australia); Drummond, Katharine J. [Royal Melbourne Hospital, Department of Neurosurgery, Parkville, Victoria (Australia)

    2011-06-15

    Protoplasmic astrocytomas are a poorly recognized and uncommon subtype of astrocytoma. While usually categorized with other low-grade gliomas, there is literature to suggest that protoplasmic astrocytomas have differences in biology compared to other gliomas in this group. This paper presents the MR imaging characteristics of a series of eight protoplasmic astrocytomas. We retrospectively reviewed MR images and histopathology of eight consecutive cases of histologically proven protoplasmic astrocytomas. Patients ranged from 17 to 51 years of age with a 5:3 male to female ratio. The tumors were located in the frontal or temporal lobes and tended to be large, well defined, and had a very high signal on T2 (close to cerebrospinal fluid). Generally, a large proportion of the tumor showed substantial signal suppression on T2 fluid-attenuated inversion recovery (FLAIR). Six of the eight lesions also demonstrated a partial or complete rim of reduced apparent diffusion coefficient (ADC) around the T2 FLAIR suppressing portion. The possibility that a primary cerebral neoplasm represents a protoplasmic astrocytoma should be considered in a patient with a large frontal or temporal tumor that has a very high signal on T2 with a large proportion of the tumor showing substantial T2 FLAIR suppression. A further clue is a partial or complete rim of reduced ADC. (orig.)

  6. Pilocytic astrocytoma: a retrospective review

    International Nuclear Information System (INIS)

    Wen, B.-C.; Mayr, Nina A.; Hitchon, Patrick W.; Kao, S.; Hussey, David H.

    1996-01-01

    Purpose: The principle objective of this study is to determine the role of radiation therapy in the management of pilocytic astrocytoma. The specific aims are to assess the results of surgical resection +/- radiation therapy, the dose-response relationships for local tumor control, and the prognostic indicators. Materials and methods: Between Jan. 1970 and Dec. 1995, 60 patients with pilocytic astrocytomas (27 cerebellum, 23 hypothalmus/brain stem, 4 temporal, 3 frontal, and 3 occipital) were seen. All pathologic slides were reviewed and confirmed. Of these, 30 patients had surgery only (8 subtotal resections and 22 total resections), 8 had biopsy followed by radiotherapy (6) or chemotherapy (2), 21 had surgery and postoperative radiotherapy (20 subtotal resections and 1 total resection) and 1 was observed only. The radiation dose was 40.6 Gy/31fr/44ds to 60.2 Gy/35fr/49ds (mean = 52.1 Gy). Results: The overall 5- and 10-year actuarial survival rate was 93% and 93%, and the relapse-free survival rate was 86% and 80%, respectively. Eight patients developed local recurrence and one had leptomeningeal spread. Two patients receiving chemotherapy (vincristine + carboplatin) had persistent but stable disease. The one patient who was observed eventually required surgical resection 25 months later. Subtotal resection without RT: The local recurrence rate was 38% ((3(8))) if no RT was given after subtotal resection. Only 2 of the 3 recurrences were salvaged. All 22 patients who had tumor totally resected had local tumor control. Subtotal resection/biopsy only plus RT: Radiation therapy was effective in controlling the gross disease in 75% ((15(20))) of patients with subtotal resection, and 100% ((6(6))) of patients with biopsy only. In 14 patients receiving a tumor dose ≥ 51 Gy, 13 (93%) had local control, in comparison, to (11(15)) (73%) receiving a tumor dose <51 Gy had tumor control. Location of tumor: Sixty-three percent ((17(27))) of patients with tumor in cerebellum

  7. Robust global identifiability theory using potentials--Application to compartmental models.

    Science.gov (United States)

    Wongvanich, N; Hann, C E; Sirisena, H R

    2015-04-01

    This paper presents a global practical identifiability theory for analyzing and identifying linear and nonlinear compartmental models. The compartmental system is prolonged onto the potential jet space to formulate a set of input-output equations that are integrals in terms of the measured data, which allows for robust identification of parameters without requiring any simulation of the model differential equations. Two classes of linear and non-linear compartmental models are considered. The theory is first applied to analyze the linear nitrous oxide (N2O) uptake model. The fitting accuracy of the identified models from differential jet space and potential jet space identifiability theories is compared with a realistic noise level of 3% which is derived from sensor noise data in the literature. The potential jet space approach gave a match that was well within the coefficient of variation. The differential jet space formulation was unstable and not suitable for parameter identification. The proposed theory is then applied to a nonlinear immunological model for mastitis in cows. In addition, the model formulation is extended to include an iterative method which allows initial conditions to be accurately identified. With up to 10% noise, the potential jet space theory predicts the normalized population concentration infected with pathogens, to within 9% of the true curve. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Epigenetic Silencing of the Protocadherin Family Member PCDH-γ-All in Astrocytomas

    Directory of Open Access Journals (Sweden)

    Anke Waha

    2005-03-01

    Full Text Available In a microarray-based methylation analysis of astrocytomas [World Health Organization (WHO grade II], we identified a CpG island within the first exon of the protocadherin-γ subfamily A11 (PCDH-γ-A11 gene that showed hypermethylation compared to normal brain tissue. Bisulfite sequencing and combined bisulfite restriction analysis (COBRA was performed to screen low- and high-grade astrocytomas for the methylation status of this CpG island. Hypermethylation was detected in 30 of 34 (88% astrocytomas (WHO grades II and III, 20 of 23 (87% glioblastomas (WHO grade IV, 8 of 8 (100% glioma cell lines. There was a highly significant correlation (P = .00028 between PCDH-γ-A11 hypermethylation and decreased transcription as determined by competitive reverse transcription polymerase chain reaction in WHO grades II and III astrocytomas. After treatment of glioma cell lines with a demethylating agent, transcription of PCDH-γ-A11 was restored. In summary, we have identified PCDH-γ-A11 as a new target silenced epigenetically in astrocytic gliomas. The inactivation of this cell-cell contact molecule might be involved in the invasive growth of astrocytoma cells into normal brain parenchyma.

  9. Childhood Astrocytoma Treatment (PDQ®)—Patient Version

    Science.gov (United States)

    Childhood astrocytomas can be benign (not cancer) or malignant (cancer). Learn more about the types of astrocytoma, signs and symptoms, diagnosis, prognosis, and treatment of astrocytomas that are newly diagnosed or have come back after treatment in this expert-reviewed summary.

  10. Robust Intratumor Partitioning to Identify High-Risk Subregions in Lung Cancer: A Pilot Study

    International Nuclear Information System (INIS)

    Wu, Jia; Gensheimer, Michael F.; Dong, Xinzhe; Rubin, Daniel L.; Napel, Sandy; Diehn, Maximilian; Loo, Billy W.; Li, Ruijiang

    2016-01-01

    Purpose: To develop an intratumor partitioning framework for identifying high-risk subregions from "1"8F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) imaging and to test whether tumor burden associated with the high-risk subregions is prognostic of outcomes in lung cancer. Methods and Materials: In this institutional review board–approved retrospective study, we analyzed the pretreatment FDG-PET and CT scans of 44 lung cancer patients treated with radiation therapy. A novel, intratumor partitioning method was developed, based on a 2-stage clustering process: first at the patient level, each tumor was over-segmented into many superpixels by k-means clustering of integrated PET and CT images; next, tumor subregions were identified by merging previously defined superpixels via population-level hierarchical clustering. The volume associated with each of the subregions was evaluated using Kaplan-Meier analysis regarding its prognostic capability in predicting overall survival (OS) and out-of-field progression (OFP). Results: Three spatially distinct subregions were identified within each tumor that were highly robust to uncertainty in PET/CT co-registration. Among these, the volume of the most metabolically active and metabolically heterogeneous solid component of the tumor was predictive of OS and OFP on the entire cohort, with a concordance index or CI of 0.66-0.67. When restricting the analysis to patients with stage III disease (n=32), the same subregion achieved an even higher CI of 0.75 (hazard ratio 3.93, log-rank P=.002) for predicting OS, and a CI of 0.76 (hazard ratio 4.84, log-rank P=.002) for predicting OFP. In comparison, conventional imaging markers, including tumor volume, maximum standardized uptake value, and metabolic tumor volume using threshold of 50% standardized uptake value maximum, were not predictive of OS or OFP, with CI mostly below 0.60 (log-rank P>.05). Conclusion: We propose a robust intratumor

  11. Robust Intratumor Partitioning to Identify High-Risk Subregions in Lung Cancer: A Pilot Study.

    Science.gov (United States)

    Wu, Jia; Gensheimer, Michael F; Dong, Xinzhe; Rubin, Daniel L; Napel, Sandy; Diehn, Maximilian; Loo, Billy W; Li, Ruijiang

    2016-08-01

    To develop an intratumor partitioning framework for identifying high-risk subregions from (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) imaging and to test whether tumor burden associated with the high-risk subregions is prognostic of outcomes in lung cancer. In this institutional review board-approved retrospective study, we analyzed the pretreatment FDG-PET and CT scans of 44 lung cancer patients treated with radiation therapy. A novel, intratumor partitioning method was developed, based on a 2-stage clustering process: first at the patient level, each tumor was over-segmented into many superpixels by k-means clustering of integrated PET and CT images; next, tumor subregions were identified by merging previously defined superpixels via population-level hierarchical clustering. The volume associated with each of the subregions was evaluated using Kaplan-Meier analysis regarding its prognostic capability in predicting overall survival (OS) and out-of-field progression (OFP). Three spatially distinct subregions were identified within each tumor that were highly robust to uncertainty in PET/CT co-registration. Among these, the volume of the most metabolically active and metabolically heterogeneous solid component of the tumor was predictive of OS and OFP on the entire cohort, with a concordance index or CI of 0.66-0.67. When restricting the analysis to patients with stage III disease (n=32), the same subregion achieved an even higher CI of 0.75 (hazard ratio 3.93, log-rank P=.002) for predicting OS, and a CI of 0.76 (hazard ratio 4.84, log-rank P=.002) for predicting OFP. In comparison, conventional imaging markers, including tumor volume, maximum standardized uptake value, and metabolic tumor volume using threshold of 50% standardized uptake value maximum, were not predictive of OS or OFP, with CI mostly below 0.60 (log-rank P>.05). We propose a robust intratumor partitioning method to identify clinically relevant, high

  12. Robust Intratumor Partitioning to Identify High-Risk Subregions in Lung Cancer: A Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jia; Gensheimer, Michael F.; Dong, Xinzhe [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Rubin, Daniel L. [Department of Radiology, Stanford University School of Medicine, Stanford, California (United States); Department of Medicine (Biomedical Informatics Research), Stanford University School of Medicine, Stanford, California (United States); Napel, Sandy [Department of Radiology, Stanford University School of Medicine, Stanford, California (United States); Diehn, Maximilian [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California (United States); Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California (United States); Loo, Billy W. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California (United States); Li, Ruijiang, E-mail: rli2@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California (United States)

    2016-08-01

    Purpose: To develop an intratumor partitioning framework for identifying high-risk subregions from {sup 18}F-fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) imaging and to test whether tumor burden associated with the high-risk subregions is prognostic of outcomes in lung cancer. Methods and Materials: In this institutional review board–approved retrospective study, we analyzed the pretreatment FDG-PET and CT scans of 44 lung cancer patients treated with radiation therapy. A novel, intratumor partitioning method was developed, based on a 2-stage clustering process: first at the patient level, each tumor was over-segmented into many superpixels by k-means clustering of integrated PET and CT images; next, tumor subregions were identified by merging previously defined superpixels via population-level hierarchical clustering. The volume associated with each of the subregions was evaluated using Kaplan-Meier analysis regarding its prognostic capability in predicting overall survival (OS) and out-of-field progression (OFP). Results: Three spatially distinct subregions were identified within each tumor that were highly robust to uncertainty in PET/CT co-registration. Among these, the volume of the most metabolically active and metabolically heterogeneous solid component of the tumor was predictive of OS and OFP on the entire cohort, with a concordance index or CI of 0.66-0.67. When restricting the analysis to patients with stage III disease (n=32), the same subregion achieved an even higher CI of 0.75 (hazard ratio 3.93, log-rank P=.002) for predicting OS, and a CI of 0.76 (hazard ratio 4.84, log-rank P=.002) for predicting OFP. In comparison, conventional imaging markers, including tumor volume, maximum standardized uptake value, and metabolic tumor volume using threshold of 50% standardized uptake value maximum, were not predictive of OS or OFP, with CI mostly below 0.60 (log-rank P>.05). Conclusion: We propose a robust

  13. Expression of estrogen and progesterone receptors in astrocytomas: a literature review

    Directory of Open Access Journals (Sweden)

    Cléciton Braga Tavares

    Full Text Available Gliomas are the most common type of primary central nervous system neoplasm. Astrocytomas are the most prevalent type of glioma and these tumors may be influenced by sex steroid hormones. A literature review for the presence of estrogen and progesterone receptors in astrocytomas was conducted in the PubMed database using the following MeSH terms: “estrogen receptor beta” OR “estrogen receptor alpha” OR “estrogen receptor antagonists” OR “progesterone receptors” OR “astrocytoma” OR “glioma” OR “glioblastoma”. Among the 111 articles identified, 13 studies met our inclusion criteria. The majority of reports showed the presence of estrogen and progesterone receptors in astrocytomas. Overall, higher tumor grades were associated with decreased estrogen receptor expression and increased progesterone receptor expression.

  14. Expression of estrogen and progesterone receptors in astrocytomas: a literature review

    Science.gov (United States)

    Tavares, Cléciton Braga; Gomes-Braga, Francisca das Chagas Sheyla Almeida; Costa-Silva, Danylo Rafhael; Escórcio-Dourado, Carla Solange; Borges, Umbelina Soares; Conde, Airton Mendes; da Conceição Barros-Oliveira, Maria; Sousa, Emerson Brandão; da Rocha Barros, Lorena; Martins, Luana Mota; Facina, Gil; da-Silva, Benedito Borges

    2016-01-01

    Gliomas are the most common type of primary central nervous system neoplasm. Astrocytomas are the most prevalent type of glioma and these tumors may be influenced by sex steroid hormones. A literature review for the presence of estrogen and progesterone receptors in astrocytomas was conducted in the PubMed database using the following MeSH terms: “estrogen receptor beta” OR “estrogen receptor alpha” OR “estrogen receptor antagonists” OR “progesterone receptors” OR “astrocytoma” OR “glioma” OR “glioblastoma”. Among the 111 articles identified, 13 studies met our inclusion criteria. The majority of reports showed the presence of estrogen and progesterone receptors in astrocytomas. Overall, higher tumor grades were associated with decreased estrogen receptor expression and increased progesterone receptor expression. PMID:27626480

  15. Malignant astrocytoma following radiotherapy for craniopharyngioma

    Energy Technology Data Exchange (ETDEWEB)

    Maat-Schieman, M.L.C.; Bots, G.T.A.M.; Thomeer, T.W.M.; Vielvoye, G.J. (Rijksuniversiteit Leiden (Netherlands). Hospital)

    1985-05-01

    The case report describes a boy with a malignant astrocytoma in the mid-line of the cerebellum 14 years after X-ray therapy for craniopharyngioma. In Leiden University Hospital this is the first case of a suspected radiation-induced brain tumour in 66 patients treated for cranial lesions by radiotherapy between 1969 and 1979 who have survived more than 5 years.

  16. Confronting Oahu's Water Woes: Identifying Scenarios for a Robust Evaluation of Policy Alternatives

    Science.gov (United States)

    van Rees, C. B.; Garcia, M. E.; Alarcon, T.; Sixt, G.

    2013-12-01

    three primary drivers of sustainability of the water supply: demand, recharge, and sea level rise. We then determined the secondary drivers shaping the primary drivers and separated them into two groups: policy-relevant drivers and external drivers. We developed a simple water balance model to calculate maximum sustainable yield based on soil properties, land cover, daily precipitation and temperature. To identify critical scenarios, the model was run over the full forecasted ranges of external drivers, such as temperature, precipitation, sea level, and population. Only the status quo of the policy drivers such as land use, water use per capita, and habitat protection has been modeled to date. However, our next steps include working with stakeholders to elicit policy strategies such as conservation regulations or zoning plans, and testing the robustness of proposed strategies with the model developed.

  17. Malignant astrocytoma following radiotherapy for craniopharyngioma

    International Nuclear Information System (INIS)

    Maat-Schieman, M.L.C.; Bots, G.T.A.M.; Thomeer, T.W.M.; Vielvoye, G.J.

    1985-01-01

    The case report describes a boy with a malignant astrocytoma in the mid-line of the cerebellum 14 years after X-ray therapy for craniopharyngioma. In Leiden University Hospital this is the first case of a suspected radiation-induced brain tumour in 66 patients treated for cranial lesions by radiotherapy between 1969 and 1979 who have survived more than 5 years. (author)

  18. Consistent robustness analysis (CRA) identifies biologically relevant properties of regulatory network models.

    Science.gov (United States)

    Saithong, Treenut; Painter, Kevin J; Millar, Andrew J

    2010-12-16

    A number of studies have previously demonstrated that "goodness of fit" is insufficient in reliably classifying the credibility of a biological model. Robustness and/or sensitivity analysis is commonly employed as a secondary method for evaluating the suitability of a particular model. The results of such analyses invariably depend on the particular parameter set tested, yet many parameter values for biological models are uncertain. Here, we propose a novel robustness analysis that aims to determine the "common robustness" of the model with multiple, biologically plausible parameter sets, rather than the local robustness for a particular parameter set. Our method is applied to two published models of the Arabidopsis circadian clock (the one-loop [1] and two-loop [2] models). The results reinforce current findings suggesting the greater reliability of the two-loop model and pinpoint the crucial role of TOC1 in the circadian network. Consistent Robustness Analysis can indicate both the relative plausibility of different models and also the critical components and processes controlling each model.

  19. Effects of diphenylhydantoin on murine astrocytoma radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Lordo, C.D.; Stroude, E.C.; Del Maestro, R.F.

    1987-01-01

    Diphenylhydantoin is a well known anticonvulsant used primarily in the treatment of epilepsy. The prophylactic use of diphenylhydantoin has been suggested for certain cerebral metastases, and it is routinely administered to prevent seizures induced by intracranial neoplasms and/or surgery. Patients with malignant gliomas treated with diphenylhydantoin frequently receive radiation therapy. The effects of a clinical concentration of diphenylhydantoin in combination with gamma radiation was investigated using the C6 astrocytoma cell line in both monolayer and three dimensional multicellular spheroid cultures. Diphenylhydantoin at 7.2 X 10(-5) M (20 micrograms/ml) significantly increased the doubling time (23%) of the C6 astrocytoma cells in monolayer, but did not affect their survival as measured by plating efficiency. No changes were seen in spheroid growth or plating efficiency of the cells dissociated from spheroids at this concentration. Diphenylhydantoin at the clinical concentration tested was not associated with an alteration in radiation sensitivity of C6 astrocytoma cells in monolayer or three dimensional multicellular spheroid cultures.

  20. 201Thallium SPECT, accuracy in astrocytoma diagnosis and treatment evaluation

    International Nuclear Information System (INIS)

    Kaellen, K.

    1999-10-01

    The aims of the studies included in this thesis were: - to investigate the reliability of 201 Thallium single photon emission computed tomography. Tl SPECT for preoperative diagnosis and histological staging of malignant astrocytomas in comparison with CT; - to develop a method for quantification of cerebral thallium uptake, and to evaluate the quantitative measurement in comparison with CT, for astrocytoma treatment follow-up purposes; - to compare quantitative Tl SPECT and proton magnetic resonance spectroscopy (H-MRS) with conventional MR imaging for astrocytoma monitoring, and to evaluate associations between change of morphological tumour characteristics during treatment and changes of cerebral thallium uptake and metabolic ratios. Results and conclusions: - High TI-index, calculated as a ratio comparing tumour uptake to uptake in the contralateral hemisphere, is an indicator of highly malignant astrocytoma. Differentiation between the high-grade astrocytomas, the low-grade astrocytomas, and infectious lesions is only partial, with an overlap of Tl-indexes between these groups. High-grade astrocytomas that do not show contrast enhancement on CT, and astrocytomas with central necrosis and moderate ring-enhancement, tend to be underestimated when evaluated by Tl-index calculation. Tl SPECT is not a reliable method for non-invasive tumour staging among the group of highly malignant astrocytomas. - Quantification of cerebral TI-uptake, defining the volume of viable tumour tissue, is a new method for astrocytoma chemotherapy monitoring. Results suggest that the method provides prognostic information, and information of treatment efficacy, at an earlier stage than CT. - We did not find a higher accuracy of quantitative Tl SPECT than of MR for monitoring purposes and our results indicated that treatment induced MR changes were interrelated with TI-uptake variations. - Multi-voxel H-MRS was difficult to apply for astrocytoma treatment monitoring, due to the anatomical

  1. Cystic astrocytomas in children. The contribution of MRI

    International Nuclear Information System (INIS)

    Vilgrain, V.; Sellier, N.; Lalande, G.; Demange, P.; Kalifa, G.

    1988-01-01

    Three cases of cystic astrocytomas are reported in children. Two are supratentorial and one is a cerebellar tumor. The authors insist on the difficulties of the diagnosis. They emphasize the role of NMR which enables distinction between cystic astrocytomas and other cysts. In agreement with Kjos, the 3 cystic astrocytomas demonstrate an increased T1 and T2 and belong to the group of cystic tumors (type II) [fr

  2. Inhibition of STAT3 reduces astrocytoma cell invasion and constitutive activation of STAT3 predicts poor prognosis in human astrocytoma.

    Directory of Open Access Journals (Sweden)

    Qinchuan Liang

    Full Text Available Astrocytoma cells characteristically possess high invasion potentials. Recent studies have revealed that knockdown of signal transducers and activators of transcription 3 (STAT3 expression by RNAi induces apoptosis in astrocytoma cell. Nevertheless, the distinct roles of STAT3 in astrocytoma's invasion and recurrence have not been elucidated. In this study, we silenced STAT3 using Small interfering RNAs in two human glioblastoma multiforme (GBM cell lines (U251 and U87, and investigated the effect on GBM cell adhesion and invasion. Our results demonstrate that disruption of STAT3 inhibits GBM cell's adhesion and invasion. Knockdown of STAT3 significantly increased E-cadherin but decreased N-cadherin, vascular endothelial growth factor, matrix metalloproteinase 2 and matrix metalloproteinase 9. Additionally, expression of pSTAT3(Tyr705 correlates with astrocytoma WHO classification, Karnofsky performance status scale score, tumor recurrence and survival. Furthermore, pSTAT3(Tyr705 is a significant prognostic factor in astrocytoma. In conclusion, STAT3 may affect astrocytoma invasion, expression of pSTAT3(Tyr705 is a significant prognostic factor in tumor recurrence and overall survival in astrocytoma patients. Therefore, STAT3 may provide a potential target for molecular therapy in human astrocytoma, and pSTAT3(Tyr705could be an important biomarker for astrocytoma prognosis.

  3. EMMPRIN expression positively correlates with WHO grades of astrocytomas and meningiomas.

    Science.gov (United States)

    Tsai, Wen-Chiuan; Chen, Ying; Huang, Li-Chun; Lee, Herng-Sheng; Ma, Hsin-I; Huang, Shih-Ming; Sytwu, Huey-Kang; Hueng, Dueng-Yuan

    2013-09-01

    High-grade primary brain tumors possessed poor outcome due to invasiveness. Extracellular matrix metalloproteinase inducer (EMMPRIN) stimulates peri-tumoral fibroblasts to secrete matrix metalloproteinase and promote invasiveness. This study hypothesized that high-grade brain tumors overexpress EMMPRIN. Analyzing the public delinked database from the Gene Expression Omnibus profile, the results showed that the EMMPRIN mRNA level was higher in WHO grade IV (n = 81) than in grade III (n = 19, p EMMPRIN levels positively correlated with WHO grades for astrocytomas (p = 0.008) and meningiomas (p = 0.048). EMMPRIN mRNA levels in conventional glioma cell lines (n = 36) was not less than those in glioma primary culture cells (n = 27) and glioblastoma stem-like cells (n = 12). The GBM8401, U87MG, and LN229 human glioma cell lines also overexpressed EMMPRIN. Hematoxylin and eosin, IHC, and immunofluorescence staining of xenografts confirmed that high-grade brain tumors overexpressed EMMPRIN. Lastly, Kaplan-Meier analysis revealed poorer survival in WHO grade IV (n = 56) than in grade III astrocytomas (n = 21, by log-rank test; p = 0.0001, 95 % CI: 1.842-3.053). However, in high-grade astrocytomas, there was no difference in survival between high and low EMMPRIN mRNA levels. Thus, this study identified that high-grade brain tumors overexpress EMMPRIN, which positively correlates with WHO grades in human astrocytomas and meningiomas, and suggests that EMMPRIN may be a therapeutic target of brain tumor.

  4. Anaplasia in pilocytic astrocytoma predicts aggressive behavior.

    Science.gov (United States)

    Rodriguez, Fausto J; Scheithauer, Bernd W; Burger, Peter C; Jenkins, Sarah; Giannini, Caterina

    2010-02-01

    The clinical significance of anaplastic features, a rare event in pilocytic astrocytoma (PA), is not fully established. We reviewed 34 PA with anaplastic features (Male = 21, Female = 13; median age 35 y, 5 to 75) among approximately 2200 PA cases (1.7%). Tumors were included which demonstrated brisk mitotic activity [at least 4 mitoses/10 high power fields (400 x )], in addition to hypercellularity and moderate-to-severe cytologic atypia, with or without necrosis. The tumors either had a PA precursor, coexistent (n = 14) (41%) or documented by previous biopsy (n = 10) (29%), or exhibited typical pilocytic features in an otherwise anaplastic astrocytoma (n = 10) (29%). Clinical features of neurofibromatosis type-1 were present in 24% and a history of radiation for PA precursor in 12%. Histologically, the anaplastic component was classified as pilocytic like (41%), small cell (32%), epithelioid (15%), or fibrillary (12%). Median MIB1 labeling index was 24.7% in the anaplastic component and 2.6% in the precursor, although overlapping values were present. Strong p53 staining (3+) was limited to areas with anaplasia (19%), with overlapping values for 1 and 2+ in areas without anaplasia. Median overall and progression-free survivals after diagnosis for the entire study group were 24 and 14 months, respectively. Overall and progression-free survivals were shorter in the setting of prior radiation for a PA precursor (P = 0.007, 0.028), increasing mitotic activity (P = 0.03, 0.02), and presence of necrosis (P = 0.02, 0.02), after adjusting for age and site. The biologic behavior of PAs with high-mitotic rates and those with necrosis paralleled that of St Anne-Mayo grades 2 and 3 diffuse astrocytomas, respectively. In summary, PA with anaplastic features exhibits a spectrum of morphologies and is associated with decreased survival when compared with typical PA.

  5. An optimization methodology for identifying robust process integration investments under uncertainty

    International Nuclear Information System (INIS)

    Svensson, Elin; Berntsson, Thore; Stroemberg, Ann-Brith; Patriksson, Michael

    2009-01-01

    Uncertainties in future energy prices and policies strongly affect decisions on investments in process integration measures in industry. In this paper, we present a five-step methodology for the identification of robust investment alternatives incorporating explicitly such uncertainties in the optimization model. Methods for optimization under uncertainty (or, stochastic programming) are thus combined with a deep understanding of process integration and process technology in order to achieve a framework for decision-making concerning the investment planning of process integration measures under uncertainty. The proposed methodology enables the optimization of investments in energy efficiency with respect to their net present value or an environmental objective. In particular, as a result of the optimization approach, complex investment alternatives, allowing for combinations of energy efficiency measures, can be analyzed. Uncertainties as well as time-dependent parameters, such as energy prices and policies, are modelled using a scenario-based approach, enabling the identification of robust investment solutions. The methodology is primarily an aid for decision-makers in industry, but it will also provide insight for policy-makers into how uncertainties regarding future price levels and policy instruments affect the decisions on investments in energy efficiency measures. (author)

  6. An optimization methodology for identifying robust process integration investments under uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Elin; Berntsson, Thore [Department of Energy and Environment, Division of Heat and Power Technology, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Stroemberg, Ann-Brith [Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Chalmers Science Park, SE-412 88 Gothenburg (Sweden); Patriksson, Michael [Department of Mathematical Sciences, Chalmers University of Technology and Department of Mathematical Sciences, University of Gothenburg, SE-412 96 Goeteborg (Sweden)

    2009-02-15

    Uncertainties in future energy prices and policies strongly affect decisions on investments in process integration measures in industry. In this paper, we present a five-step methodology for the identification of robust investment alternatives incorporating explicitly such uncertainties in the optimization model. Methods for optimization under uncertainty (or, stochastic programming) are thus combined with a deep understanding of process integration and process technology in order to achieve a framework for decision-making concerning the investment planning of process integration measures under uncertainty. The proposed methodology enables the optimization of investments in energy efficiency with respect to their net present value or an environmental objective. In particular, as a result of the optimization approach, complex investment alternatives, allowing for combinations of energy efficiency measures, can be analyzed. Uncertainties as well as time-dependent parameters, such as energy prices and policies, are modelled using a scenario-based approach, enabling the identification of robust investment solutions. The methodology is primarily an aid for decision-makers in industry, but it will also provide insight for policy-makers into how uncertainties regarding future price levels and policy instruments affect the decisions on investments in energy efficiency measures. (author)

  7. Current treatment of low grade astrocytoma

    DEFF Research Database (Denmark)

    Pedersen, Christina Louise; Romner, Bertil

    2013-01-01

    Through a comprehensive review of the current literature, the present article investigates several aspects of low grade astrocytomas (LGA), including prognostic factors, treatment strategies and follow-up regimes. LGA are in general relatively slow-growing primary brain tumours, but they have a v...... effective in discriminating between tumour progression and radiation necrosis. The research into biomarkers is currently limited with regards to their applications in LGA diagnostics, and therefore further studies including larger patient populations are needed.......Through a comprehensive review of the current literature, the present article investigates several aspects of low grade astrocytomas (LGA), including prognostic factors, treatment strategies and follow-up regimes. LGA are in general relatively slow-growing primary brain tumours, but they have...... as the course of disease. The current literature seems to support the idea that treatment with radical tumour resection, where possible, yields better long term outcome for patients with LGA. However, adjuvant therapy is often necessary. Administering early postoperative radiotherapy to patients with partially...

  8. Identifying spikes and seasonal components in electricity spot price data: A guide to robust modeling

    International Nuclear Information System (INIS)

    Janczura, Joanna; Trück, Stefan; Weron, Rafał; Wolff, Rodney C.

    2013-01-01

    An important issue in fitting stochastic models to electricity spot prices is the estimation of a component to deal with trends and seasonality in the data. Unfortunately, estimation routines for the long-term and short-term seasonal pattern are usually quite sensitive to extreme observations, known as electricity price spikes. Improved robustness of the model can be achieved by (a) filtering the data with some reasonable procedure for outlier detection, and then (b) using estimation and testing procedures on the filtered data. In this paper we examine the effects of different treatments of extreme observations on model estimation and on determining the number of spikes (outliers). In particular we compare results for the estimation of the seasonal and stochastic components of electricity spot prices using either the original or filtered data. We find significant evidence for a superior estimation of both the seasonal short-term and long-term components when the data have been treated carefully for outliers. Overall, our findings point out the substantial impact the treatment of extreme observations may have on these issues and, therefore, also on the pricing of electricity derivatives like futures and option contracts. An added value of our study is the ranking of different filtering techniques used in the energy economics literature, suggesting which methods could be and which should not be used for spike identification. - Highlights: • First comprehensive study on the impact of spikes on seasonal pattern estimation • The effects of different treatments of spikes on model estimation are examined. • Cleaning spot prices for outliers yields superior estimates of the seasonal pattern. • Removing outliers provides better parameter estimates for the stochastic process. • Rankings of filtering techniques suggested in the literature are provided

  9. Pilocytic Astrocytoma Presenting as an Orbital Encephalocele: A Case Report

    Directory of Open Access Journals (Sweden)

    Amy Bruzek

    2015-04-01

    Full Text Available We describe the case of a 29-year-old male who presented with new-onset seizures. He was subsequently found to have an orbital encephalocele containing a focus of pilocytic astrocytoma. We believe that this is the first report of a pilocytic astrocytoma located within the orbit that did not originate from the optic pathway. It is also the first case of a pilocytic astrocytoma completely contained within an encephalocele. This case suggests a close pathological examination of encephaloceles for underlying diseases.

  10. Radiotherapy Results of Brain Astrocytoma and Glioblastoma Multiforme

    International Nuclear Information System (INIS)

    Choi, Doo Ho; Kim, Il Han; Ha, Sung Whan; Chi, Je Geun

    1988-01-01

    A retrospective analysis was performed on 49 patients with astrocytoma of glioblastoma multiforme of brain who received postoperative radiotherapy in the period between February 1979 and December 1985. Fourteen patients had grade I astrocytoma, 11 patients grade II, 14 patients grade III, and 10 patients glioblastoma multiforme. Three year actuarial survival rates were 85.7%, 44.6% and 23.1% for grade I, II, and III astrocytomas, respectively. One and 2 year actuarial survival rates for patients with glioblastoma multiforme were 54.5% and 27.3%, respectively. Histologic grade, age, extent of operation and tumor location were revealed to be prognosticators

  11. Computed tomography of benign supratentorial astrocytomas of infancy and childhood

    International Nuclear Information System (INIS)

    Pedersen, H.; Gjerris, F.; Klinken, L.

    1981-01-01

    The CT findings of 15 benign supratentorial astrocytomas in children less than 15 years of age are compared with the CT findings of 19 supratentorial tumors of other histological types in the same age group. Astrocytomas were more often hypodense, lacked calcification and showed greater contrast enhancement than other tumors. Seven of the 15 astrocytomas were hypodense, without calcification and showed contrast enhancement of more than 10 Hounsfield units, whereas this coexistence was not present in any of the 19 tumors of the other histological types. (orig.)

  12. A rapid and robust method of identifying transformed Arabidopsis thaliana seedlings following floral dip transformation

    Directory of Open Access Journals (Sweden)

    Gray John C

    2006-11-01

    Full Text Available Abstract Background The floral dip method of transformation by immersion of inflorescences in a suspension of Agrobacterium is the method of choice for Arabidopsis transformation. The presence of a marker, usually antibiotic- or herbicide-resistance, allows identification of transformed seedlings from untransformed seedlings. Seedling selection is a lengthy process which does not always lead to easily identifiable transformants. Selection for kanamycin-, phosphinothricin- and hygromycin B-resistance commonly takes 7–10 d and high seedling density and fungal contamination may result in failure to recover transformants. Results A method for identifying transformed seedlings in as little as 3.25 d has been developed. Arabidopsis T1 seeds obtained after floral dip transformation are plated on 1% agar containing MS medium and kanamycin, phosphinothricin or hygromycin B, as appropriate. After a 2-d stratification period, seeds are subjected to a regime of 4–6 h light, 48 h dark and 24 h light (3.25 d. Kanamycin-resistant and phosphinothricin-resistant seedlings are easily distinguished from non-resistant seedlings by green expanded cotyledons whereas non-resistant seedlings have pale unexpanded cotyledons. Seedlings grown on hygromycin B differ from those grown on kanamycin and phosphinothricin as both resistant and non-resistant seedlings are green. However, hygromycin B-resistant seedlings are easily identified as they have long hypocotyls (0.8–1.0 cm whereas non-resistant seedlings have short hypocotyls (0.2–0.4 cm. Conclusion The method presented here is an improvement on current selection methods as it allows quicker identification of transformed seedlings: transformed seedlings are easily discernable from non-transformants in as little as 3.25 d in comparison to the 7–10 d required for selection using current protocols.

  13. A Two-Step Method to Identify Positive Deviant Physician Organizations of Accountable Care Organizations with Robust Performance Management Systems.

    Science.gov (United States)

    Pimperl, Alexander F; Rodriguez, Hector P; Schmittdiel, Julie A; Shortell, Stephen M

    2018-06-01

    To identify positive deviant (PD) physician organizations of Accountable Care Organizations (ACOs) with robust performance management systems (PMSYS). Third National Survey of Physician Organizations (NSPO3, n = 1,398). Organizational and external factors from NSPO3 were analyzed. Linear regression estimated the association of internal and contextual factors on PMSYS. Two cutpoints (75th/90th percentiles) identified PDs with the largest residuals and highest PMSYS scores. A total of 65 and 41 PDs were identified using 75th and 90th percentiles cutpoints, respectively. The 90th percentile more strongly differentiated PDs from non-PDs. Having a high proportion of vulnerable patients appears to constrain PMSYS development. Our PD identification method increases the likelihood that PD organizations selected for in-depth inquiry are high-performing organizations that exceed expectations. © Health Research and Educational Trust.

  14. Impaired RNA splicing of 5'-regulatory sequences of the astroglial glutamate transporter EAAT2 in human astrocytoma

    NARCIS (Netherlands)

    Münch, C.; Penndorf, A.; Schwalenstöcker, B.; Troost, D.; Ludolph, A. C.; Ince, P.; Meyer, T.

    2001-01-01

    A loss of the glutamate transporter EAAT2 has been reported in the neoplastic transformation of astrocytic cells and astrocytoma. The RNA expression of EAAT2 and five 5'-regulatory splice variants was investigated to identify alterations of the post-transcriptional EAAT2 gene regulation in human

  15. Completed Ensemble Empirical Mode Decomposition: a Robust Signal Processing Tool to Identify Sequence Strata

    Science.gov (United States)

    Purba, H.; Musu, J. T.; Diria, S. A.; Permono, W.; Sadjati, O.; Sopandi, I.; Ruzi, F.

    2018-03-01

    Well logging data provide many geological information and its trends resemble nonlinear or non-stationary signals. As long well log data recorded, there will be external factors can interfere or influence its signal resolution. A sensitive signal analysis is required to improve the accuracy of logging interpretation which it becomes an important thing to determine sequence stratigraphy. Complete Ensemble Empirical Mode Decomposition (CEEMD) is one of nonlinear and non-stationary signal analysis method which decomposes complex signal into a series of intrinsic mode function (IMF). Gamma Ray and Spontaneous Potential well log parameters decomposed into IMF-1 up to IMF-10 and each of its combination and correlation makes physical meaning identification. It identifies the stratigraphy and cycle sequence and provides an effective signal treatment method for sequence interface. This method was applied to BRK- 30 and BRK-13 well logging data. The result shows that the combination of IMF-5, IMF-6, and IMF-7 pattern represent short-term and middle-term while IMF-9 and IMF-10 represent the long-term sedimentation which describe distal front and delta front facies, and inter-distributary mouth bar facies, respectively. Thus, CEEMD clearly can determine the different sedimentary layer interface and better identification of the cycle of stratigraphic base level.

  16. A case of astrocytoma, 19 year history after BNCT

    International Nuclear Information System (INIS)

    Kamano, Shuji

    2006-01-01

    A 39-year-old man had received Boron Neutron Capture Therapy (BNCT) in 1987 for a Grade II Astrocytoma. He gradually exacerbated and received a second operation in 1994. The mass taken in the second operation is almost competent with radiation necrosis. Following that, he shows no signs of recurrence. Currently, he has returned to full time employment in physical labor. This case suggests effectiveness of BNCT for rather low-grade astrocytomas. (author)

  17. Statistical analyses of scatterplots to identify important factors in large-scale simulations, 2: robustness of techniques

    International Nuclear Information System (INIS)

    Kleijnen, J.P.C.; Helton, J.C.

    1999-01-01

    The robustness of procedures for identifying patterns in scatterplots generated in Monte Carlo sensitivity analyses is investigated. These procedures are based on attempts to detect increasingly complex patterns in the scatterplots under consideration and involve the identification of (i) linear relationships with correlation coefficients, (ii) monotonic relationships with rank correlation coefficients, (iii) trends in central tendency as defined by means, medians and the Kruskal-Wallis statistic, (iv) trends in variability as defined by variances and interquartile ranges, and (v) deviations from randomness as defined by the chi-square statistic. The following two topics related to the robustness of these procedures are considered for a sequence of example analyses with a large model for two-phase fluid flow: the presence of Type I and Type II errors, and the stability of results obtained with independent Latin hypercube samples. Observations from analysis include: (i) Type I errors are unavoidable, (ii) Type II errors can occur when inappropriate analysis procedures are used, (iii) physical explanations should always be sought for why statistical procedures identify variables as being important, and (iv) the identification of important variables tends to be stable for independent Latin hypercube samples

  18. Benefits of using an optimization methodology for identifying robust process integration investments under uncertainty-A pulp mill example

    International Nuclear Information System (INIS)

    Svensson, Elin; Berntsson, Thore; Stroemberg, Ann-Brith

    2009-01-01

    This paper presents a case study on the optimization of process integration investments in a pulp mill considering uncertainties in future electricity and biofuel prices and CO 2 emissions charges. The work follows the methodology described in Svensson et al. [Svensson, E., Berntsson, T., Stroemberg, A.-B., Patriksson, M., 2008b. An optimization methodology for identifying robust process integration investments under uncertainty. Energy Policy, in press, (doi:10.1016/j.enpol.2008.10.023)] where a scenario-based approach is proposed for the modelling of uncertainties. The results show that the proposed methodology provides a way to handle the time dependence and the uncertainties of the parameters. For the analyzed case, a robust solution is found which turns out to be a combination of two opposing investment strategies. The difference between short-term and strategic views for the investment decision is analyzed and it is found that uncertainties are increasingly important to account for as a more strategic view is employed. Furthermore, the results imply that the obvious effect of policy instruments aimed at decreasing CO 2 emissions is, in applications like this, an increased profitability for all energy efficiency investments, and not as much a shift between different alternatives

  19. Benefits of using an optimization methodology for identifying robust process integration investments under uncertainty-A pulp mill example

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Elin [Department of Energy and Environment, Division of Heat and Power Technology, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)], E-mail: elin.svensson@chalmers.se; Berntsson, Thore [Department of Energy and Environment, Division of Heat and Power Technology, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Stroemberg, Ann-Brith [Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Chalmers Science Park, SE-412 88 Gothenburg (Sweden)

    2009-03-15

    This paper presents a case study on the optimization of process integration investments in a pulp mill considering uncertainties in future electricity and biofuel prices and CO{sub 2} emissions charges. The work follows the methodology described in Svensson et al. [Svensson, E., Berntsson, T., Stroemberg, A.-B., Patriksson, M., 2008b. An optimization methodology for identifying robust process integration investments under uncertainty. Energy Policy, in press, (doi:10.1016/j.enpol.2008.10.023)] where a scenario-based approach is proposed for the modelling of uncertainties. The results show that the proposed methodology provides a way to handle the time dependence and the uncertainties of the parameters. For the analyzed case, a robust solution is found which turns out to be a combination of two opposing investment strategies. The difference between short-term and strategic views for the investment decision is analyzed and it is found that uncertainties are increasingly important to account for as a more strategic view is employed. Furthermore, the results imply that the obvious effect of policy instruments aimed at decreasing CO{sub 2} emissions is, in applications like this, an increased profitability for all energy efficiency investments, and not as much a shift between different alternatives.

  20. Benefits of using an optimization methodology for identifying robust process integration investments under uncertainty. A pulp mill example

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Elin; Berntsson, Thore [Department of Energy and Environment, Division of Heat and Power Technology, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Stroemberg, Ann-Brith [Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Chalmers Science Park, SE-412 88 Gothenburg (Sweden)

    2009-03-15

    This paper presents a case study on the optimization of process integration investments in a pulp mill considering uncertainties in future electricity and biofuel prices and CO{sub 2} emissions charges. The work follows the methodology described in Svensson et al. [Svensson, E., Berntsson, T., Stroemberg, A.-B., Patriksson, M., 2008b. An optimization methodology for identifying robust process integration investments under uncertainty. Energy Policy, in press, doi:10.1016/j.enpol.2008.10.023] where a scenario-based approach is proposed for the modelling of uncertainties. The results show that the proposed methodology provides a way to handle the time dependence and the uncertainties of the parameters. For the analyzed case, a robust solution is found which turns out to be a combination of two opposing investment strategies. The difference between short-term and strategic views for the investment decision is analyzed and it is found that uncertainties are increasingly important to account for as a more strategic view is employed. Furthermore, the results imply that the obvious effect of policy instruments aimed at decreasing CO{sub 2} emissions is, in applications like this, an increased profitability for all energy efficiency investments, and not as much a shift between different alternatives. (author)

  1. Multiple solid pilocytic astrocytomas in cerebleiium with neurofibromatosis type: A case report

    International Nuclear Information System (INIS)

    Choi, Seo Young; Kim, Myung Soon; Kim, Young Ju

    2014-01-01

    Pilocytic astrocytoma usually has a classic imaging manifestation of a solitary, cyst-like mass with a strong contrast-enhancing mural nodule. There is only one published report so far of multiple solid and cyst type pilocytic astrocytomas in the cerebellum in neurofibromatosis type 1 (NF1) patient from the United States in 2007. We report a case of pilocytic astrocytoma presenting with only solid, multiple pilocytic astrocytomas in the cerebellum in NF1 patient.

  2. Holocord low grade astrocytoma - Role of radical irradiation and chemotherapy

    International Nuclear Information System (INIS)

    Goyal, S.; Puri, T.; Julka, R.K.

    2015-01-01

    Spinal intradural tumors, especially those extending along the entire length of the spinal cord, termed as ‘holocord’ tumors are uncommon. Most of these are gliomas, with astrocytomas (low grade) predominating in children and ependymomas in adults. Other histologies, though reported, are even rarer. Management is debatable, with both surgery and radiotherapy of such extensive tumors posing challenges. We describe a case of a 14-year-old girl with holocord astrocytoma extending from cervicomedullary junction till lumbar spine, who recovered full neurological function following radical irradiation of entire spine followed by temozolomide-based chemotherapy. No grade 3/4 bone marrow morbidity was seen. Five years following treatment, she maintained normal neurological function and apparently normal pubertal and skeletal growth despite residual disease visible on imaging. Literature review of existing reports of holocord astrocytomas highlighting management and outcome is presented.

  3. 13N-NH3 PET in the diagnosis of astrocytomas: preliminary result

    International Nuclear Information System (INIS)

    Zhang Xiangsong; He Zuoxiang; Tang Anwu

    2004-01-01

    Objective: To evaluate the feasibility of diagnosing the astrocytoma with 13N-NH3 PET imaging. Methods 13N-NH3 and 18F-fluorodeoxyglucose (FDG) PET imaging were performed in seven cases of astrocytomas including 3 anteoperative astrocytomas, 2 recurrent astrocytomas, 2 brain injury or necrosis after the operation and radiotherapy. The radioactivity ratios of the tumor and normal white matter (T/WM) were calculated. Results: The tumor lesions in 3 anteoperative astrocytomas and 2 recurrent astrocytomas all uptake 13N-NH3. The average T/WM on 13N-NH3 images was 1.82±0.21, and T/WM on 13N-NH3 and 18F-FDG images were 1.98 and 0.97 for one case with grade 1 astrocytoma. 13N-NH3 and 18F-FDG PET imaging both showed decreased uptake in 2 brain injury or necrosis after the operation and radiotherapy of astrocytomas. Conclusions: 13N-NH3 was uptaken in astrocytomas. 13N-NH3 can be useful in the diagnosis of astrocytoma, and potentially improve diagnostic accuracy of astrocytoma, especially in low-grade astrocytoma. (authors)

  4. 13N-NH3 PET in the diagnosis of astrocytomas: preliminary result

    International Nuclear Information System (INIS)

    Zhang Xiangsong; He Zuoxiang; Tang Anwu

    2004-01-01

    Objective: To evaluate the feasibility of diagnosing the astrocytoma with 13N-NH3 PET imaging. Methods: 13N-NH3 and 18F-fluorodeoxyglucose (FDG) PET imaging were performed in seven cases of astrocytomas including 3 anteoperative astrocytomas, 2 recurrent astrocytomas, 2 brain injury or necrosis after the operation and radiotherapy. The radioactivity ratios of the tumor and normal white matter (T/WM) were calculated. Results: The tumor lesions in 3 anteoperative astrocytomas and 2 recurrent astrocytomas all uptake 13N-NH3 .The average T/WM on 13N-NH3 images was 1.82±0.21, and T/WM on 13N-NH3 and 18F-FDG images were 1.98 and 0.97 for one case with grade 1 astrocytoma. 13N-NH3 and 18F-FDG PET imaging both showed decreased uptake in 2 brain injury or necrosis after the operation and radiotherapy of astrocytomas. Conclusions: 13N-NH3 was uptaken in astrocytomas. 13N-NH3 can be useful in the diagnosis of astrocytoma, and potentially improve diagnostic accuracy of astrocytoma, especially in low-grade astrocytoma. (authors)

  5. Using multiobjective tradeoff sets and Multivariate Regression Trees to identify critical and robust decisions for long term water utility planning

    Science.gov (United States)

    Smith, R.; Kasprzyk, J. R.; Balaji, R.

    2017-12-01

    In light of deeply uncertain factors like future climate change and population shifts, responsible resource management will require new types of information and strategies. For water utilities, this entails potential expansion and efficient management of water supply infrastructure systems for changes in overall supply; changes in frequency and severity of climate extremes such as droughts and floods; and variable demands, all while accounting for conflicting long and short term performance objectives. Multiobjective Evolutionary Algorithms (MOEAs) are emerging decision support tools that have been used by researchers and, more recently, water utilities to efficiently generate and evaluate thousands of planning portfolios. The tradeoffs between conflicting objectives are explored in an automated way to produce (often large) suites of portfolios that strike different balances of performance. Once generated, the sets of optimized portfolios are used to support relatively subjective assertions of priorities and human reasoning, leading to adoption of a plan. These large tradeoff sets contain information about complex relationships between decisions and between groups of decisions and performance that, until now, has not been quantitatively described. We present a novel use of Multivariate Regression Trees (MRTs) to analyze tradeoff sets to reveal these relationships and critical decisions. Additionally, when MRTs are applied to tradeoff sets developed for different realizations of an uncertain future, they can identify decisions that are robust across a wide range of conditions and produce fundamental insights about the system being optimized.

  6. Glioblastomas, astrocytomas and oligodendrogliomas linked to Lynch syndrome

    DEFF Research Database (Denmark)

    Therkildsen, C; Ladelund, S; Rambech, E

    2015-01-01

    .5%) in MSH2 gene mutation carriers compared to patients with mutations in MLH1 or MSH6. Glioblastomas predominated (56%), followed by astrocytomas (22%) and oligodendrogliomas (9%). MMR status was assessed in 10 tumors, eight of which showed MMR defects. None of these tumors showed immunohistochemical...

  7. Childhood Astrocytomas Treatment (PDQ®)—Health Professional Version

    Science.gov (United States)

    Astrocytoma is the most common type of glioma in children. Get detailed information about the clinical features, molecular and diagnostic evaluation, classification, prognosis, and treatment of newly diagnosed and recurrent disease low-grade and high-grade gliomas in this comprehensive summary for clinicians.

  8. Anorexia: an early sign of fourth ventricle astrocytoma in children.

    Science.gov (United States)

    Leroy, Henri-Arthur; Baroncini, Marc; Delestret, Isabelle; Florent, Vincent; Vinchon, Matthieu

    2014-12-01

    Paediatric low-grade astrocytomas of the fourth ventricle are rare tumours, generally revealed by hydrocephalus. However, some patients present with a history of severe anorexia. It might be a harbinger, which if recognized, could lead to earlier diagnosis. We decided to examine our database in order to evaluate the incidence and signification of anorexia in this context. Retrospective monocentric study of cases of low-grade astrocytomas of the fourth ventricle operated between 1991 and 2012 in our paediatric neurosurgery department. We particularly observed the clinical presentation and long-term clinical, oncological and radiological evolution. Non-parametrical tests were used (Mann-Whitney, Fisher). We reviewed 34 cases, 31 pilocytic astrocytomas and 3 diffuse astrocytomas, 16 boys and 18 girls, (M/F ratio 0.89). Mean age at diagnosis was 8 years old. Seven presented with notable anorexia, the average BMI in this group was ≤2 standard deviation (SD); with clinical signs evolving for 11.5 months. Twenty-seven children had no anorexia; average BMI in this group was +1 SD, with clinical evolution for 6 months on an average of p anorexia, body mass index improved markedly in the postoperative follow-up, which lasted, on average, for 6 years. Anorexia with stunted body weight curve is a non-exceptional presentation in children with low-grade astrocytomas of the fourth ventricle. Unexplained or atypical anorexia with negative etiologic assessment should prompt cerebral imaging. Clinical improvement after surgical resection, could suggest a possible interaction between tumour tissue and appetite-suppressing peptide secretion.

  9. MR signal of the solid portion of pilocytic astrocytoma on T2-weighted images: is it useful for differentiation from medulloblastoma?

    International Nuclear Information System (INIS)

    Arai, Kiyokazu; Yagi, Akiko; Taketomi-Takahashi, Ayako; Morita, Hideo; Koyama, Yoshinori; Endo, Keigo; Sato, Noriko; Aoki, Jun; Oba, Hiroshi; Ishiuchi, Shogo; Saito, Nobuhito

    2006-01-01

    Background and purpose: Although imaging features of cerebellar pilocytic astrocytoma and medulloblastoma have been described in many texts, original comparisons of magnetic resonance intensity between these two tumours are limited. In the present study the results of magnetic resonance imaging (MRI) were reviewed, focusing especially on the signal intensity of the solid portion of these neoplasms. Methods: MR images of ten cerebellar pilocytic astrocytomas and ten medulloblastomas were reviewed. The signal intensities of the solid components were graded on a scale of 1 to 5, with higher scores indicating a signal intensity closer to that of water. The degree of enhancement, tumour cysts and peripheral oedema were evaluated on MR images. When the solid portion was heterogeneous (i.e. mixed signal intensity or degree of enhancement), the dominant area was selected for evaluation. On T2-weighted images, the signal intensity of the solid portion was equal to that of cerebrospinal fluid (CSF) in 50% of pilocytic astrocytomas. No medulloblastomas showed such hyperintensity. Most medulloblastomas (80%) were isointense to grey matter. On T1-weighted images, the signal intensity varied widely in pilocytic astrocytomas; however, all medulloblastomas were iso- or hypointense to grey matter. The MR enhancement pattern, cystic component and peripheral oedema all varied in both tumour types and no specific features were identified. A signal intensity of the solid portion isointense to CSF on T2-weighted images was characteristic of cerebellar pilocytic astrocytomas; this was not observed in medulloblastomas. Attention to T2-weighted imaging of the solid portions of a tumour is easy and helpful in differentiating between cerebellar pilocytic astrocytoma and medulloblastoma. (orig.)

  10. Expression of delta-catenin is associated with progression of human astrocytoma

    International Nuclear Information System (INIS)

    MingHao, Wang; Qianze, Dong; Di, Zhang; YunJie, Wang

    2011-01-01

    δ-Catenin (CTNND2), which encodes a scaffold protein in humans, has been found in a few malignancies. However, the expression pattern and contribution of δ-catenin to astrocytoma progression are unclear. We investigated δ-catenin expression in human astrocytoma samples and its function in astrocytoma cell lines using immunohistochemistry, siRNA knockdown, transfection, MTT, transwell migration and Rac1 pulldown techniques. δ-Catenin protein expression was detected in cytoplasm of astrocytoma cells by immunohistochemistry. Analysis showed that grade I astrocytoma (0%, 0/11) and glial cells from normal brain tissue exhibited negative staining. δ-Catenin expression was significantly higher in grade III-IV (35%, 29/84) compared to grade II astrocytoma cells (18%, 11/61); p < 0.01). In addition, CTNND2 overexpression promoted proliferation, invasion and Rac1 activity of U251 astrocytoma cells. Treatment of δ-catenin-transfected cells with a Rac1 inhibitor decreased Rac1 activity and invasion. δ-Catenin knockdown in U87 glioblastoma cell decreased cell proliferation, invasion and Rac1 activity. The results suggest that δ-catenin expression is associated with the malignant progression of astrocytoma and promotes astrocytoma cell invasion through upregulation of Rac1 activity. δ-Catenin expression levels may serve as a useful marker of the biological behavior of astrocytoma cells

  11. Robust Selection Algorithm (RSA) for Multi-Omic Biomarker Discovery; Integration with Functional Network Analysis to Identify miRNA Regulated Pathways in Multiple Cancers.

    Science.gov (United States)

    Sehgal, Vasudha; Seviour, Elena G; Moss, Tyler J; Mills, Gordon B; Azencott, Robert; Ram, Prahlad T

    2015-01-01

    MicroRNAs (miRNAs) play a crucial role in the maintenance of cellular homeostasis by regulating the expression of their target genes. As such, the dysregulation of miRNA expression has been frequently linked to cancer. With rapidly accumulating molecular data linked to patient outcome, the need for identification of robust multi-omic molecular markers is critical in order to provide clinical impact. While previous bioinformatic tools have been developed to identify potential biomarkers in cancer, these methods do not allow for rapid classification of oncogenes versus tumor suppressors taking into account robust differential expression, cutoffs, p-values and non-normality of the data. Here, we propose a methodology, Robust Selection Algorithm (RSA) that addresses these important problems in big data omics analysis. The robustness of the survival analysis is ensured by identification of optimal cutoff values of omics expression, strengthened by p-value computed through intensive random resampling taking into account any non-normality in the data and integration into multi-omic functional networks. Here we have analyzed pan-cancer miRNA patient data to identify functional pathways involved in cancer progression that are associated with selected miRNA identified by RSA. Our approach demonstrates the way in which existing survival analysis techniques can be integrated with a functional network analysis framework to efficiently identify promising biomarkers and novel therapeutic candidates across diseases.

  12. Astrocytoma of the pituitary gland (pituicytoma): case report

    International Nuclear Information System (INIS)

    Uesaka, T.; Miyazono, M.; Nishio, S.; Iwaki, T.

    2002-01-01

    A 34-year-old man presented with a 4-month history of visual obscuration. Magnetic resonance imaging showed a solid, discrete, contrast-enhancing pituitary mass with suprasellar extension. Surgery, which was performed via a transsphenoidal approach, disclosed the pituitary tumor to be a fibrillary astrocytoma (pituicytoma). This case report contains the clinical and neuroimaging features of this rare tumor of the neurohypophysis, which masqueraded as a pituitary adenoma. (orig.)

  13. Tuberous schlerosis complex and astrocytoma: a case report, Hiroshima

    Energy Technology Data Exchange (ETDEWEB)

    Rudnick, P A; Hoshino, N; Kitaoka, T; Miura, M

    1961-02-10

    This case report concerned a young woman with cutaneous, osseous, and retinal changes of tuberous sclerosis, referred to ABCC for evaluation of blindness and increased intracranial pressure. A right lateral ventricle astrocytoma was successfully removed, but the patient's sight was not restored. The development of cerebral neoplasms in these patients is discussed. A careful search for resectable brain lesions should be made in all patients with tuberous sclerosis who have signs and symptoms of increased intracranial pressure. 14 references, 6 figures.

  14. Promoter hypermethylation of mismatch repair gene hMLH1 predicts the clinical response of malignant astrocytomas to nitrosourea.

    Science.gov (United States)

    Fukushima, Takao; Katayama, Yoichi; Watanabe, Takao; Yoshino, Atsuo; Ogino, Akiyoshi; Ohta, Takashi; Komine, Chiaki

    2005-02-15

    In certain types of human cancers, transcriptional inactivation of hMLH1 by promoter hypermethylation plays a causal role in the loss of mismatch repair functions that modulate cytotoxic pathways in response to DNA-damaging agents. The aim of the present study was to investigate the role of promoter methylation of the hMLH1 gene in malignant astrocytomas. We examined the hMLH1 promoter methylation in a homogeneous cohort of patients with 41 malignant astrocytomas treated by 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-2(2-chloroethyl)-3-nitrosourea chemotherapy in combination with radiation and interferon therapy, and assessed the correlation of such methylation with clinical outcome. hMLH1 promoter methylation was found in 6 (15%) of the 41 newly diagnosed malignant astrocytomas. Hypermethylation of the hMLH1 promoter corresponded closely with a loss of immunohistochemical staining for hMLH1 protein (P = 0.0013). Patients with hMLH1-methylated tumors displayed a greater chance of responding to adjuvant therapy as compared with those with hMLH1-unmethylated tumors (P = 0.0150). The presence of hMLH1 hypermethylation was significantly associated with a longer progression-free survival on both univariate analysis (P = 0.0340) and multivariate analysis (P = 0.0161). The present study identified hMLH1 methylation status as a predictor of the clinical response of malignant astrocytomas to chloroethylnitrosourea-based adjuvant therapy. The findings obtained suggest that determination of the methylation status of hMLH1 could provide a potential basis for designing rational chemotherapeutic strategies, as well as for predicting prognosis.

  15. {sup 201}Thallium SPECT, accuracy in astrocytoma diagnosis and treatment evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Kaellen, K

    1999-10-01

    The aims of the studies included in this thesis were: - to investigate the reliability of {sup 201}Thallium single photon emission computed tomography. Tl SPECT for preoperative diagnosis and histological staging of malignant astrocytomas in comparison with CT; - to develop a method for quantification of cerebral thallium uptake, and to evaluate the quantitative measurement in comparison with CT, for astrocytoma treatment follow-up purposes; - to compare quantitative Tl SPECT and proton magnetic resonance spectroscopy (H-MRS) with conventional MR imagingfor astrocytoma monitoring, and to evaluate associations between change of morphological tumour characteristics during treatment and changes of cerebral thallium uptake and metabolic ratios. Results and conclusions: - High TI-index, calculated as a ratio comparing tumour uptake to uptake in the contralateral hemisphere, is an indicator of highly malignant astrocytoma. Differentiation between the high-grade astrocytomas, the low-grade astrocytomas, and infectious lesions is only partial, with an overlap of Tl-indexes between these groups. High-grade astrocytomas that do not show contrast enhancement on CT, and astrocytomas with central necrosis and moderate ring-enhancement, tend to be underestimated when evaluated by Tl-index calculation. Tl SPECT is not a reliable method for non-invasive tumour staging among the group of highly malignant astrocytomas. - Quantification of cerebral TI-uptake, defining the volume of viable tumour tissue, is a new method for astrocytoma chemotherapy monitoring. Results suggest that the method provides prognostic information, and information of treatment efficacy, at an earlier stage than CT. - We did not find a higher accuracy of quantitative Tl SPECT than of MR for monitoring purposes and our results indicated that treatment induced MR changes were interrelated with TI-uptake variations. - Multi-voxel H-MRS was difficult to apply for astrocytoma treatment monitoring, due to the

  16. Expression of aquaporin8 in human astrocytomas: Correlation with pathologic grade

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Shu-juan; Wang, Ke-jian; Gan, Sheng-wei; Xu, Jin; Xu, Shi-ye; Sun, Shan-quan, E-mail: sunsq2151@cqmu.edu.cn

    2013-10-11

    Highlights: •AQP8 is mainly distributed in the cytoplasm of human astrocytoma cells. •AQP8 over-expressed in human astrocytomas, especially glioblastoma. •The up-regulation of AQP8 is related to the pathological grade of human astrocytomas. •AQP8 may contribute to the growth and proliferation of astrocytomas. -- Abstract: Aquaporin8 (AQP8), a member of the aquaporin (AQP) protein family, is weakly distributed in mammalian brains. Previous studies on AQP8 have focused mainly on the digestive and the reproductive systems. AQP8 has a pivotal role in keeping the fluid and electrolyte balance. In this study, we investigated the expression changes of AQP8 in 75 cases of human brain astrocytic tumors using immunohistochemistry, Western blotting, and reverse transcription polymerase chain reaction. The results demonstrated that AQP8 was mainly distributed in the cytoplasm of astrocytoma cells. The expression levels and immunoreactive score of AQP8 protein and mRNA increased in low-grade astrocytomas, and further increased in high-grade astrocytomas, especially in glioblastoma. Therefore, AQP8 may contribute to the proliferation of astrocytomas, and may be a biomarker and candidate therapy target for patients with astrocytomas.

  17. Malignant transformation of a chiasmatic pilocytic astrocytoma in a patient with diencephalic syndrome

    International Nuclear Information System (INIS)

    Wal, Ester P.J. van der; Edwards-Brown, Mary; Azzarelli, Biagio

    2003-01-01

    Chiasmatic gliomas with metastatic spread are rare in children and are usually associated with diencephalic syndrome. They are mostly pilocytic astrocytomas and their transformation to high-grade astrocytomas has never previously been reported in the pediatric population. We report leptomeningeal spread of a chiasmatic pilocytic astrocytoma in a child presenting with diencephalic syndrome. He was treated with chemotherapy and radiation. The tumor recurred with transformation into a high-grade astrocytoma. Radiation therapy may have played a role in transformation of the tumor, but more research is needed to further clarify the biological behavior of this tumor. (orig.)

  18. Expression of aquaporin8 in human astrocytomas: Correlation with pathologic grade

    International Nuclear Information System (INIS)

    Zhu, Shu-juan; Wang, Ke-jian; Gan, Sheng-wei; Xu, Jin; Xu, Shi-ye; Sun, Shan-quan

    2013-01-01

    Highlights: •AQP8 is mainly distributed in the cytoplasm of human astrocytoma cells. •AQP8 over-expressed in human astrocytomas, especially glioblastoma. •The up-regulation of AQP8 is related to the pathological grade of human astrocytomas. •AQP8 may contribute to the growth and proliferation of astrocytomas. -- Abstract: Aquaporin8 (AQP8), a member of the aquaporin (AQP) protein family, is weakly distributed in mammalian brains. Previous studies on AQP8 have focused mainly on the digestive and the reproductive systems. AQP8 has a pivotal role in keeping the fluid and electrolyte balance. In this study, we investigated the expression changes of AQP8 in 75 cases of human brain astrocytic tumors using immunohistochemistry, Western blotting, and reverse transcription polymerase chain reaction. The results demonstrated that AQP8 was mainly distributed in the cytoplasm of astrocytoma cells. The expression levels and immunoreactive score of AQP8 protein and mRNA increased in low-grade astrocytomas, and further increased in high-grade astrocytomas, especially in glioblastoma. Therefore, AQP8 may contribute to the proliferation of astrocytomas, and may be a biomarker and candidate therapy target for patients with astrocytomas

  19. A Sensitive and Specific Diagnostic Panel to Distinguish Diffuse Astrocytoma from Astrocytosis: Chromosome 7 Gain with Mutant Isocitrate Dehydrogenase 1 and p53

    Science.gov (United States)

    Camelo-Piragua, Sandra; Jansen, Michael; Ganguly, Aniruddha; Kim, J. ChulMin; Cosper, Arjola K.; Dias-Santagata, Dora; Nutt, Catherine L.; Iafrate, A. John; Louis, David N.

    2011-01-01

    One of the major challenges of surgical neuropathology is the distinction of diffuse astrocytoma (World Health Organization [WHO] grade II) from astrocytosis. The most commonly used ancillary tool to solve this problem is p53 immunohistochemistry (IHC), but this is neither sensitive nor specific. Isocitrate dehydrogenase 1 (IDH1) mutations are common in lower grade gliomas, with most causing a specific amino acid change (R132H) that can be detected with a monoclonal antibody. IDH2 mutations are rare, but also occur in gliomas. In addition, gains of chromosome 7 are common in gliomas. In this study we assessed the status of p53, IDH1/2 and chromosome 7 to determine the most useful panel to distinguish astrocytoma from astrocytosis. We studied biopsy specimens from 21 WHO grade II diffuse astrocytomas and 20 reactive conditions. The single most sensitive test to identify astrocytoma is fluorescence in situ hybridization (FISH) for chromosome 7 gain (76.2%). The combination of p53 and mutant IDH1 IHC provides a higher sensitivity (71.4%) than either test alone (47.8%); this combination offers a practical initial approach for the surgical pathologist. The best overall sensitivity (95%) is achieved when FISH for chromosome 7 gain is added to the p53-mutant IDH1 IHC panel. PMID:21343879

  20. Directed International Technological Change and Climate Policy: New Methods for Identifying Robust Policies Under Conditions of Deep Uncertainty

    Science.gov (United States)

    Molina-Perez, Edmundo

    It is widely recognized that international environmental technological change is key to reduce the rapidly rising greenhouse gas emissions of emerging nations. In 2010, the United Nations Framework Convention on Climate Change (UNFCCC) Conference of the Parties (COP) agreed to the creation of the Green Climate Fund (GCF). This new multilateral organization has been created with the collective contributions of COP members, and has been tasked with directing over USD 100 billion per year towards investments that can enhance the development and diffusion of clean energy technologies in both advanced and emerging nations (Helm and Pichler, 2015). The landmark agreement arrived at the COP 21 has reaffirmed the key role that the GCF plays in enabling climate mitigation as it is now necessary to align large scale climate financing efforts with the long-term goals agreed at Paris 2015. This study argues that because of the incomplete understanding of the mechanics of international technological change, the multiplicity of policy options and ultimately the presence of climate and technological change deep uncertainty, climate financing institutions such as the GCF, require new analytical methods for designing long-term robust investment plans. Motivated by these challenges, this dissertation shows that the application of new analytical methods, such as Robust Decision Making (RDM) and Exploratory Modeling (Lempert, Popper and Bankes, 2003) to the study of international technological change and climate policy provides useful insights that can be used for designing a robust architecture of international technological cooperation for climate change mitigation. For this study I developed an exploratory dynamic integrated assessment model (EDIAM) which is used as the scenario generator in a large computational experiment. The scope of the experimental design considers an ample set of climate and technological scenarios. These scenarios combine five sources of uncertainty

  1. Identifying the Gene Signatures from Gene-Pathway Bipartite Network Guarantees the Robust Model Performance on Predicting the Cancer Prognosis

    Directory of Open Access Journals (Sweden)

    Li He

    2014-01-01

    Full Text Available For the purpose of improving the prediction of cancer prognosis in the clinical researches, various algorithms have been developed to construct the predictive models with the gene signatures detected by DNA microarrays. Due to the heterogeneity of the clinical samples, the list of differentially expressed genes (DEGs generated by the statistical methods or the machine learning algorithms often involves a number of false positive genes, which are not associated with the phenotypic differences between the compared clinical conditions, and subsequently impacts the reliability of the predictive models. In this study, we proposed a strategy, which combined the statistical algorithm with the gene-pathway bipartite networks, to generate the reliable lists of cancer-related DEGs and constructed the models by using support vector machine for predicting the prognosis of three types of cancers, namely, breast cancer, acute myeloma leukemia, and glioblastoma. Our results demonstrated that, combined with the gene-pathway bipartite networks, our proposed strategy can efficiently generate the reliable cancer-related DEG lists for constructing the predictive models. In addition, the model performance in the swap analysis was similar to that in the original analysis, indicating the robustness of the models in predicting the cancer outcomes.

  2. miR-106a-5p inhibits the proliferation and migration of astrocytoma cells and promotes apoptosis by targeting FASTK.

    Directory of Open Access Journals (Sweden)

    Feng Zhi

    Full Text Available Astrocytomas are common malignant intracranial tumors that comprise the majority of adult primary central nervous system tumors. MicroRNAs (miRNAs are small, non-coding RNAs (20-24 nucleotides that post-transcriptionally modulate gene expression by negatively regulating the stability or translational efficiency of their target mRNAs. In our previous studies, we found that the downregulation of miR-106a-5p in astrocytomas is associated with poor prognosis. However, its specific gene target(s and underlying functional mechanism(s in astrocytomas remain unclear. In this study, we used mRNA microarray experiments to measure global mRNA expression in the presence of increased or decreased miR-106a-5p levels. We then performed bioinformatics analysis based on multiple target prediction algorithms to obtain candidate target genes that were further validated by computational predictions, western blot analysis, quantitative real-time PCR, and the luciferase reporter assay. Fas-activated serine/threonine kinase (FASTK was identified as a direct target of miR-106a-5p. In human astrocytomas, miR-106a-5p is downregulated and negatively associated with clinical staging, whereas FASTK is upregulated and positively associated with advanced clinical stages, at both the protein and mRNA levels. Furthermore, Kaplan-Meier analysis revealed that the reduced expression of miR-106a-5p or the increased expression of FASTK is significantly associated with poor survival outcome. These results further supported the finding that FASTK is a direct target gene of miR-106a-5p. Next, we explored the function of miR-106a-5p and FASTK during astrocytoma progression. Through gain-of-function and loss-of-function studies, we demonstrated that miR-106a-5p can significantly inhibit cell proliferation and migration and can promote cell apoptosis in vitro. The knockdown of FASTK induced similar effects on astrocytoma cells as those induced by the overexpression of miR-106a-5p. These

  3. Outcome of Patients With Pilocytic Astrocytoma and Leptomeningeal Dissemination

    Energy Technology Data Exchange (ETDEWEB)

    Mazloom, Ali; Hodges, Joseph C.; Teh, Bin S. [Department of Radiation Oncology, Methodist Hospital, Houston, TX (United States); Chintagumpala, Murali [Department of Pediatrics, Baylor College of Medicine, Houston, TX (United States); Paulino, Arnold C., E-mail: apaulino@tmhs.org [Department of Radiation Oncology, Methodist Hospital, Houston, TX (United States); Department of Pediatrics, Baylor College of Medicine, Houston, TX (United States)

    2012-10-01

    Purpose: To determine the patient, tumor, and treatment characteristics of patients with pilocytic astrocytoma (PA) and leptomeningeal dissemination (LMD). Methods and Materials: A PubMed search of English-language studies pertaining to PA with LMD was performed using a combination of keywords that included juvenile pilocytic astrocytoma, low-grade astrocytoma, low-grade glioma, leptomeningeal dissemination, neuraxis spread, and radiotherapy. We found 26 studies with 58 patients between 1976 and 2005 that met these criteria. Results: The median survival for PA patients with LMD was 65 months. The 1-, 2-, and 5-year overall survival (OS) rate after the diagnosis of LMD was 81.1%, 75.7%, and 55.5%. The 1-, 2-, and 5-year progression-free survival (PFS) rate after the diagnosis of LMD was 69.3%, 66.5%, and 34.6%, respectively. Age, gender, primary site location, timing of LMD presentation (synchronous vs. metachronous), and LMD location did not significantly influence OS or PFS. No statistically significant difference was found in OS or PFS between the chemotherapy and radiotherapy groups. Likewise, no difference was found in OS or PFS according to the use of craniospinal irradiation vs. less extensive RT fields. Conclusions: Approximately one-half of PA patients were alive 5 years after the diagnosis of LMD. Both chemotherapy and radiotherapy have efficacy against LMD. Although the use of craniospinal irradiation did not have an effect on PFS, the patient numbers were small and a larger number treated with craniospinal irradiation is needed to determine its efficacy.

  4. The value of multi ultra high-b-value DWI in grading cerebral astrocytomas and its association with aquaporin-4.

    Science.gov (United States)

    Tan, Yan; Zhang, Hui; Wang, Xiao-Chun; Qin, Jiang-Bo; Wang, Le

    2018-06-01

    To investigate the value of multi-ultrahigh-b-value diffusion-weighted imaging (UHBV-DWI) in differentiating high-grade astrocytomas (HGAs) from low-grade astrocytomas (LGAs), analyze its association with aquaporin (AQP) expression. 40 astrocytomas divided into LGAs (N = 15) and HGAs (N = 25) were studied. Apparent diffusion coefficient (ADC) and UHBV-ADC values in solid parts and peritumoral edema were compared between LGAs and HGAs groups by the t-test. Using receiver operating characteristic curves to identify the better parameter. Using real time polymerase chain reaction to assess AQP messenger ribonucleic acid (mRNA). Using spearman correlation analysis to assess the correlation of AQP mRNA with each parameter. ADC values in solid parts of HGAs were significantly lower than LGAs (p = 0.02), while UHBV-ADC values of HGAs were significantly higher than LGAs (p  0.05); ADC value showed a negative correlation with AQP4 mRNA (r = -0.357; p = 0.024). UHBV-ADC value positively correlated with the AQP4 mRNA (r = 0.646; p value may be related with the AQP4 mRNA levels. UHBV-DWI could be of value in the assessment of astrocytoma. Advances in knowledge: UHBV-DWI generated by multi UHBV could have particular value for astrocytoma grading, and the level of AQP4 mRNA might be potentially linked to the change of UHBV-DWI parameter, and we might find the exact reason for the difference of UHBV-ADC between the LGAs and HGAs.

  5. Radical proposal for the treatment of malignant astrocytoma

    International Nuclear Information System (INIS)

    Karlsson, U.; Black, P.; Nair, S.; Yablon, J.S.; Brady, L.W.

    1991-01-01

    The traditional treatment for anaplastic astrocytoma (AAF) and glioblastoma multiforme (GBM) leads to local relapse. The recurring element is assumed to be previously radioresistant, reorganizing hypoxic cells that require up to three times the traditional photon irradiation dose for inactivation. We are proposing to coagulate the original lesion with high-dose precision brachytherapy, immediately followed by resection to save the patient from secondary effects of the necrotic region. The treatment then continues with adjuvant external beam radiation therapy to the local surrounding brain and concomitant chemotherapy. The approach inverts the traditional regimen. It has the virtue of being precise, avoiding secondary effects of the necrotic tumor, and satisfying accepted radiobiological principles

  6. Management of Pediatric Spinal Cord Astrocytomas: Outcomes With Adjuvant Radiation

    International Nuclear Information System (INIS)

    Guss, Zachary D.; Moningi, Shalini; Jallo, George I.; Cohen, Kenneth J.; Wharam, Moody D.; Terezakis, Stephanie A.

    2013-01-01

    Purpose: Pediatric intramedullary spinal cord tumors are exceedingly rare; in the United States, 100 to 200 cases are recognized annually, of these, most are astrocytomas. The purpose of this study is to report the outcomes in pediatric patients with spinal cord astrocytomas treated at a tertiary care center. Methods and Materials: An institutional review board-approved retrospective single-institution study was performed for pediatric patients with spinal cord astrocytomas treated at our hospital from 1990 to 2010. The patients were evaluated on the extent of resection, progression-free survival (PFS), and development of radiation-related toxicities. Kaplan-Meier curves and multivariate regression model methods were used for analysis. Results: Twenty-nine patients were included in the study, 24 with grade 1 or 2 (low-grade) tumors and 5 with grade 3 or 4 (high-grade) tumors. The median follow-up time was 55 months (range, 1-215 months) for patients with low-grade tumors and 17 months (range, 10-52 months) for those with high-grade tumors. Thirteen patients in the cohort received chemotherapy. All patients underwent at least 1 surgical resection. Twelve patients received radiation therapy to a median radiation dose of 47.5 Gy (range, 28.6-54.0 Gy). Fifteen patients with low-grade tumors and 1 patient with a high-grade tumor exhibited stable disease at the last follow-up visit. Acute toxicities of radiation therapy were low grade, whereas long-term sequelae were infrequent and manageable when they arose. All patients with low-grade tumors were alive at the last follow-up visit, compared with 1 patient with a high-grade tumor. Conclusion: Primary pediatric spinal cord astrocytomas vary widely in presentation and clinical course. Histopathologic grade remains a major prognostic factor. Patients with low-grade tumors tend to have excellent disease control and long-term survival compared to those with high-grade tumors. This experience suggests that radiation therapy

  7. Management of Pediatric Spinal Cord Astrocytomas: Outcomes With Adjuvant Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Guss, Zachary D.; Moningi, Shalini [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins Hospital, Baltimore, Maryland (United States); Jallo, George I. [Department of Neurosurgery, Johns Hopkins Hospital, Baltimore, Maryland (United States); Cohen, Kenneth J. [Division of Pediatric Oncology, Johns Hopkins Hospital, Baltimore, Maryland (United States); Wharam, Moody D. [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins Hospital, Baltimore, Maryland (United States); Terezakis, Stephanie A., E-mail: stereza1@jhmi.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins Hospital, Baltimore, Maryland (United States)

    2013-04-01

    Purpose: Pediatric intramedullary spinal cord tumors are exceedingly rare; in the United States, 100 to 200 cases are recognized annually, of these, most are astrocytomas. The purpose of this study is to report the outcomes in pediatric patients with spinal cord astrocytomas treated at a tertiary care center. Methods and Materials: An institutional review board-approved retrospective single-institution study was performed for pediatric patients with spinal cord astrocytomas treated at our hospital from 1990 to 2010. The patients were evaluated on the extent of resection, progression-free survival (PFS), and development of radiation-related toxicities. Kaplan-Meier curves and multivariate regression model methods were used for analysis. Results: Twenty-nine patients were included in the study, 24 with grade 1 or 2 (low-grade) tumors and 5 with grade 3 or 4 (high-grade) tumors. The median follow-up time was 55 months (range, 1-215 months) for patients with low-grade tumors and 17 months (range, 10-52 months) for those with high-grade tumors. Thirteen patients in the cohort received chemotherapy. All patients underwent at least 1 surgical resection. Twelve patients received radiation therapy to a median radiation dose of 47.5 Gy (range, 28.6-54.0 Gy). Fifteen patients with low-grade tumors and 1 patient with a high-grade tumor exhibited stable disease at the last follow-up visit. Acute toxicities of radiation therapy were low grade, whereas long-term sequelae were infrequent and manageable when they arose. All patients with low-grade tumors were alive at the last follow-up visit, compared with 1 patient with a high-grade tumor. Conclusion: Primary pediatric spinal cord astrocytomas vary widely in presentation and clinical course. Histopathologic grade remains a major prognostic factor. Patients with low-grade tumors tend to have excellent disease control and long-term survival compared to those with high-grade tumors. This experience suggests that radiation therapy

  8. Tuberous schlerosis complex and astrocytoma: a case report, Hiroshima

    Energy Technology Data Exchange (ETDEWEB)

    Rudnick, P.A.; Hoshino, N.; Kitaoka, T.; Miura, M.

    1961-02-10

    This case report concerned a young woman with cutaneous, osseous, and retinal changes of tuberous sclerosis, referred to ABCC for evaluation of blindness and increased intracranial pressure. A right lateral ventricle astrocytoma was successfully removed, but the patient's sight was not restored. The development of cerebral neoplasms in these patients is discussed. A careful search for resectable brain lesions should be made in all patients with tuberous sclerosis who have signs and symptoms of increased intracranial pressure. 14 references, 6 figures.

  9. Evaluation of miR-362 Expression in Astrocytoma of Human Brain Tumors

    Directory of Open Access Journals (Sweden)

    Majid Kheirollahi

    2017-01-01

    Full Text Available Background: Patients affected by gliomas have a poor prognosis. Astrocytoma is a subtype of glioma. Identification of biomarkers could be an effective way to an early diagnosis of tumor or to distinguish more aggressive tumors that need more intensive therapy. In this study, we investigated whether the expression of miR-362 was increased or decreased in patients with different grades of astrocytoma. Materials and Methods: miR-362 expression was compared in 25 patients with astrocytoma with that of 4 normal nonneoplastic brain tissues. Results: In all tumor tissues, the expression of miR-362 was significantly decreased relative to its expression in normal brain tissues. However, there was no significant difference between miR-362 expressions in high and low grades of astrocytoma. Conclusions: In conclusion, miR-362 showed a down-regulation pattern in astrocytoma tissues that was different from the pattern obtained from previously published microarray studies.

  10. Optic nerve pilomyxoid astrocytoma in a patient with Noonan syndrome.

    Science.gov (United States)

    Nair, Sushmita; Fort, John A; Yachnis, Anthony T; Williams, Charles A

    2015-06-01

    Noonan syndrome (NS; MIM 163950) is an autosomal dominant syndrome which is clinically diagnosed by the distinct facial features, short stature, cardiac anomalies and developmental delay. About 50% of cases are associated with gain of function mutations in PTPN11 gene which leads to activation of the RAS/mitogen-activated protein kinase signaling pathway. This is known to have a role in tumorigenesis. Despite this, only limited reports of solid tumors (Fryssira H, Leventopoulos G, Psoni S, et al. Tumor development in three patients with Noonan syndrome. Eur J Pediatr 2008;167:1025-1031; Schuettpelz LG, McDonald S, Whitesell K et al. Pilocytic astrocytoma in a child with Noonan syndrome. Pediatr Blood Cancer 2009;53:1147-1149; Sherman CB, Ali-Nazir A, Gonzales-Gomez I, et al. Primary mixed glioneuronal tumor of the central nervous system in a patient with Noonan syndrome. J Pediatr Hematol Oncol 2009;31:61-64; Sanford RA, Bowman R, Tomita T, et al. A 16 year old male with Noonan's syndrome develops progressive scoliosis and deteriorating gait. Pediatr Neurosurg 1999;30:47-52) and no prior reports of optic gliomas have been described in patients with NS. We present here a patient with NS with a PTPN11 mutation and an optic pathway pilomyxoid astrocytoma. © 2015 Wiley Periodicals, Inc.

  11. High dose rate brachytherapy in treatment of high grade astrocytomas

    International Nuclear Information System (INIS)

    Garcia-Alejo, R.; Delgado, J.M.; Cerro, E. del; Torres, J.J.; Martinez, R.

    1996-01-01

    From May 1994 to June 1995, 18 patients with high grade astrocytomas were entered prospectively on a selective protocol combining surgery, external beam radiotherapy, stereotactic interstitial implantation with HDR Iridium 192 and chemotherapy. Only those patients with tumor size 100cc or less average dimension, high grade astrocytoma, Karnofsky 70 or greater, unilateral, circumscribed, unifocal, tumor stable or responding to external radiation and supratentorial were included in the study. Ages ranged from 16 to 69 years. There were 13 males and 5 females. Surgery consisted of biopsy only in 3 patients, subtotal resection in 11, and gross total resection in 4 patients. Focal external beam radiation portals included the contrast enhancing mass on CT scan plus a 3 cm margin. The protocol called for minimum tumor dose of 60 Gy to be given in 2 Gy daily fractions. An interstitial brachytherapy boost was to be performed two weeks after the conclusion of external beam radiation. The dose was 30 Gy in 4 fractions. The authors analyze on basis on their personal experience, the possibilities and the limits offered by this therapeutic procedure in neuro-oncology. Using stereotactic techniques, interstitial brachytherapy of brain tumors was technically possible with negligible acute morbidity and mortality, and appeared to be effective and may provide for an increase in tumor control in selected cases

  12. Leptomeningeal dissemination of an astrocytoma causing hypophyseal insufficiency

    International Nuclear Information System (INIS)

    Suzan, S.; Cigdem, O.; Furkan, U.; Baki, A.

    2012-01-01

    Full text: Introduction: Hypophyseal insufficiency is an unusual clinical presentation of metastatic disease. Objectives: In this report, a case of leptomeningeal metastasis of an astrocytoma to the infundibular recess, causing hypophyseal insufficiency is presented with its magnetic resonance imaging (MRI) findings. Materials and methods: A 27-year-old woman presented with nausea, vomiting and generalized weakness. Her laboratory results were consistent with hypopituitarism. She had an operation history for astrocytoma. She was referred to radiology department for brain MRI study. Contrast-enhanced MRI scan showed extensive wall enhancement of ventricles consistent with leptomeningeal metastases. A nodular mass with pronounced contrast enhancement was also detected at the infundibular stalk. Results: Because suprasellar cistern was normal and extensive leptomeningeal metastases was detected, the nodular mass at the infundibular stalk thought to be secondary to leptomeningeal involvement of the infundibular recess. Conclusion: When a patient with a known malignancy presented with hypophyseal insufficiency, it should be thought that leptomeningeal metastases to the infundibular recess may also be a cause. The neuroimaging, especially contrast-enhanced studies, is necessary for the confirmation

  13. Conformal proton radiation therapy for pediatric low-grade astrocytomas

    International Nuclear Information System (INIS)

    Hug, E.B.; Loma Linda Univ. Medical Center, Loma Linda, CA; Darthmouth-Hitchcock Medical Center, Lebanon, New Hampshire; Muenter, M.W.; Archambeau, J.O.; DeVries, A.; Loredo, L.N.; Grove, R.I.; Slater, J.D.; Liwnicz, B.

    2002-01-01

    Background: To evaluate the safety and efficacy of proton radiation therapy (PRT) for intracranial low-grade astrocytomas, the authors analyzed the first 27 pediatric patients treated at Loma Linda University Medical Center (LLUMC). Patients and Method: Between September 1991 and August 1997, 27 patients (13 female, 14 male) underwent fractionated proton radiation therapy for progressive or recurrent low-grade astrocytoma. Age at time of treatment ranged from 2 to 18 years (mean: 8.7 years). Tumors were located centrally (diencephatic) in 15 patients, in the cerebral and cerebellar hemispheres in seven patients, and in the brainstem in five patients. 25/27 patients (92%) were treated for progressive, unresectable, or residual disease following subtotal resection. Tissue diagnosis was available in 23/27 patients (85%). Four patients with optic pathway tumors were treated without histologic confirmation. Target doses between 50.4 and 63.0 CGE (cobalt gray equivalent, mean: 55.2 CGE) were prescribed at 1.8 CGE per fraction, five treatments per week. Results: At a mean follow-up period of 3.3 years (0.6-6.8 years), 6/27 patients experienced local failure (all located within the irradiated field), and 4/27 patients had died. By anatomic site these data translated into rates of local control and survival of 87% (13/15 patients) and 93% (14/15 patients) for central tumors, 71% (5/7 patients) and 86% (6/7 patients) for hemispheric tumors, and 60% (3/5 patients) and 60% (3/5 patients) for tumors located in the brainstem. Proton radiation therapy was generally well tolerated. All children with local control maintained their performance status. One child with associated neurofibromatosis, Type 1, developed Moyamoya disease. All six patients with optic pathway tumors and useful vision maintained or improved their visual status. Conclusions: This report on pediatric low-grade astrocytomas confirms proton radiation therapy as a safe and efficacious 3-D conformal treatment

  14. Expression and prognostic impact of matrix metalloproteinase-2 (MMP-2) in astrocytomas

    DEFF Research Database (Denmark)

    Ramachandran, Rahimsan K.; Sørensen, Mia D.; Aaberg-Jessen, Charlotte

    2017-01-01

    with diffuse astrocytoma, anaplastic astrocytoma and glioblastoma were stained immunohistochemically using a monoclonal MMP-2 antibody. The MMP-2 intensity in cytoplasm/membrane was quantified by a trained software-based classifier using systematic random sampling in 10% of the tumor area. We found MMP-2...... of this tumor. Matrix metalloproteinase-2 (MMP-2) is an extracellular matrix degrading enzyme which has been shown to play important roles in different cancers. The aim of this study was to investigate the expression and prognostic potential of MMP-2 in astrocytomas. Tissue samples from 89 patients diagnosed...

  15. Fast neutron boost for the treatment of grade IV astrocytomas

    International Nuclear Information System (INIS)

    Breteau, N.; Destembert, B.; Favre, A.; Pheline, C.; Schlienger, M.

    1989-01-01

    A previous study, on grade IV astrocytomas, compared a combination of photons and fast neutron boost to photons only, both treatments being delivered following a concentrated irradiation schedule. A slight improvement in survival was observed after neutron boost for non operated patients, but not for operated patients. Since death was always related to local recurrence and since no complication occurred after neutron boost, the neutron dose was increased from 6 to 7 Gy in January 1985. No improvement in survival was observed for patients treated with neutron boost after complete resection. After subtotal resection, the group that was treated with the higher neutron boost (7 Gy) showed a significant benefit in survival at twelve months. When patients had only a biopsy before irradiation, there was a benefit in survival after neutron boost, but no additional benefit was gained when the size of the neutron boost was increased from 6 to 7 Gy. (orig.) [de

  16. Prognostic significance of multiple kallikreins in high-grade astrocytoma

    International Nuclear Information System (INIS)

    Drucker, Kristen L.; Gianinni, Caterina; Decker, Paul A.; Diamandis, Eleftherios P.; Scarisbrick, Isobel A.

    2015-01-01

    Kallikreins have clinical value as prognostic markers in a subset of malignancies examined to date, including kallikrein 3 (prostate specific antigen) in prostate cancer. We previously demonstrated that kallikrein 6 is expressed at higher levels in grade IV compared to grade III astrocytoma and is associated with reduced survival of GBM patients. In this study we determined KLK1, KLK6, KLK7, KLK8, KLK9 and KLK10 protein expression in two independent tissue microarrays containing 60 grade IV and 8 grade III astrocytoma samples. Scores for staining intensity, percent of tumor stained and immunoreactivity scores (IR, product of intensity and percent) were determined and analyzed for correlation with patient survival. Grade IV glioma was associated with higher levels of kallikrein-immunostaining compared to grade III specimens. Univariable Cox proportional hazards regression analysis demonstrated that elevated KLK6- or KLK7-IR was associated with poor patient prognosis. In addition, an increased percent of tumor immunoreactive for KLK6 or KLK9 was associated with decreased survival in grade IV patients. Kaplan-Meier survival analysis indicated that patients with KLK6-IR < 10, KLK6 percent tumor core stained < 3, or KLK7-IR < 9 had a significantly improved survival. Multivariable analysis indicated that the significance of these parameters was maintained even after adjusting for gender and performance score. These data suggest that elevations in glioblastoma KLK6, KLK7 and KLK9 protein have utility as prognostic markers of patient survival. The online version of this article (doi:10.1186/s12885-015-1566-5) contains supplementary material, which is available to authorized users

  17. Transcriptional profiles of pilocytic astrocytoma are related to their three different locations, but not to radiological tumor features

    International Nuclear Information System (INIS)

    Zakrzewski, Krzysztof; Jarząb, Michał; Pfeifer, Aleksandra; Oczko-Wojciechowska, Małgorzata; Jarząb, Barbara; Liberski, Paweł P.; Zakrzewska, Magdalena

    2015-01-01

    Pilocytic astrocytoma is the most common type of brain tumor in the pediatric population, with a generally favorable prognosis, although recurrences or leptomeningeal dissemination are sometimes also observed. For tumors originating in the supra-or infratentorial location, a different molecular background was suggested, but plausible correlations between the transcriptional profile and radiological features and/or clinical course are still undefined. The purpose of this study was to identify gene expression profiles related to the most frequent locations of this tumor, subtypes based on various radiological features, and the clinical pattern of the disease. Eighty six children (55 males and 31 females) with histologically verified pilocytic astrocytoma were included in this study. Their age at the time of diagnosis ranged from fourteen months to seventeen years, with a mean age of seven years. There were 40 cerebellar, 23 optic tract/hypothalamic, 21 cerebral hemispheric, and two brainstem tumors. According to the radiological features presented on MRI, all cases were divided into four subtypes: cystic tumor with a non-enhancing cyst wall; cystic tumor with an enhancing cyst wall; solid tumor with central necrosis; and solid or mainly solid tumor. In 81 cases primary surgical resection was the only and curative treatment, and in five cases progression of the disease was observed. In 47 cases the analysis was done by using high density oligonucleotide microarrays (Affymetrix HG-U133 Plus 2.0) with subsequent bioinformatic analyses and confirmation of the results by independent RT-qPCR (on 39 samples). Bioinformatic analyses showed that the gene expression profile of pilocytic astrocytoma is highly dependent on the tumor location. The most prominent differences were noted for IRX2, PAX3, CXCL14, LHX2, SIX6, CNTN1 and SIX1 genes expression even within different compartments of the supratentorial region. Analysis of the genes potentially associated with radiological

  18. High concentration of Daunorubicin and Daunorubicinol in human malignant astrocytomas after systemic administration of liposomal Daunorubicin

    NARCIS (Netherlands)

    Albrecht, K. W.; de Witt Hamer, P. C.; Leenstra, S.; Bakker, P. J.; Beijnen, J. H.; Troost, D.; Kaaijk, P.; Bosch, A. D.

    2001-01-01

    The value of chemotherapy in patients with malignant astrocytoma remains controversial. In our laboratories in vitro experiments with organotypic spheroid cultures showed superior effectiveness of anthracyclines. Systemic administration did not provide in therapeutic concentrations so far. Because

  19. Study on the correlation between VEGF and peritumoral edema and tumor border in astrocytoma by CT

    International Nuclear Information System (INIS)

    Ye Yuxiang; Tan Siping; Liu Bo; Liu Guorui; Zhen Zhichao; Fan Miao

    2004-01-01

    Objective: To study the correlation between VEGF and peritumoral edema and tumor border in human astrocytoma, investigate the significance of its CT features in molecular-biology. Methods: The VEGF was examined by means of SP immunohistochemical technique in 52 cases of astrocytoma proved by pathology. The correlation of tumor VEGF with peritumoral edema, and tumor border was analyzed. Results: The peritumoral edema, tumor border and mass effect of astrocytoma was positively correlated with its VEGF. The VEGF increased with peritumoral edema and mass effect (P<0.01). VEGF were significantly higher in uncertain border group than those the clear border group (P<0.05), which VEGF were 69.2 ± 19.0. Conclusion: The over expression of VEGF obviously effect CT features in astrocytoma, such as peritumoral edema and tumor border

  20. SU-D-207B-05: Robust Intra-Tumor Partitioning to Identify High-Risk Subregions for Prognosis in Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J; Gensheimer, M; Dong, X; Rubin, D; Napel, S; Diehn, M; Loo, B; Li, R [Stanford University, Palo Alto, CA (United States)

    2016-06-15

    Purpose: To develop an intra-tumor partitioning framework for identifying high-risk subregions from 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) and CT imaging, and to test whether tumor burden associated with the high-risk subregions is prognostic of outcomes in lung cancer. Methods: In this institutional review board-approved retrospective study, we analyzed the pre-treatment FDG-PET and CT scans of 44 lung cancer patients treated with radiotherapy. A novel, intra-tumor partitioning method was developed based on a two-stage clustering process: first at patient-level, each tumor was over-segmented into many superpixels by k-means clustering of integrated PET and CT images; next, tumor subregions were identified by merging previously defined superpixels via population-level hierarchical clustering. The volume associated with each of the subregions was evaluated using Kaplan-Meier analysis regarding its prognostic capability in predicting overall survival (OS) and out-of-field progression (OFP). Results: Three spatially distinct subregions were identified within each tumor, which were highly robust to uncertainty in PET/CT co-registration. Among these, the volume of the most metabolically active and metabolically heterogeneous solid component of the tumor was predictive of OS and OFP on the entire cohort, with a concordance index or CI = 0.66–0.67. When restricting the analysis to patients with stage III disease (n = 32), the same subregion achieved an even higher CI = 0.75 (HR = 3.93, logrank p = 0.002) for predicting OS, and a CI = 0.76 (HR = 4.84, logrank p = 0.002) for predicting OFP. In comparison, conventional imaging markers including tumor volume, SUVmax and MTV50 were not predictive of OS or OFP, with CI mostly below 0.60 (p < 0.001). Conclusion: We propose a robust intra-tumor partitioning method to identify clinically relevant, high-risk subregions in lung cancer. We envision that this approach will be applicable to identifying useful

  1. ADAR2 editing activity in newly diagnosed versus relapsed pediatric high-grade astrocytomas

    International Nuclear Information System (INIS)

    Tomaselli, Sara; Galeano, Federica; Massimi, Luca; Di Rocco, Concezio; Lauriola, Libero; Mastronuzzi, Angela; Locatelli, Franco; Gallo, Angela

    2013-01-01

    High-grade (WHO grade III and IV) astrocytomas are aggressive malignant brain tumors affecting humans with a high risk of recurrence in both children and adults. To date, limited information is available on the genetic and molecular alterations important in the onset and progression of pediatric high-grade astrocytomas and, even less, on the prognostic factors that influence long-term outcome in children with recurrence. A-to-I RNA editing is an essential post-transcriptional mechanism that can alter the nucleotide sequence of several RNAs and is mediated by the ADAR enzymes. ADAR2 editing activity is particularly important in mammalian brain and is impaired in both adult and pediatric high-grade astrocytomas. Moreover, we have recently shown that the recovered ADAR2 activity in high-grade astrocytomas inhibits in vivo tumor growth. The aim of the present study is to investigate whether changes may occur in ADAR2-mediated RNA editing profiles of relapsed high-grade astrocytomas compared to their respective specimens collected at diagnosis, in four pediatric patients. Total RNAs extracted from all tumor samples and controls were tested for RNA editing levels (by direct sequencing on cDNA pools) and for ADAR2 mRNA expression (by qRT-PCR). A significant loss of ADAR2-editing activity was observed in the newly diagnosed and recurrent astrocytomas in comparison to normal brain. Surprisingly, we found a substantial rescue of ADAR2 editing activity in the relapsed tumor of the only patient showing prolonged survival. High-grade astrocytomas display a generalized loss of ADAR2-mediated RNA editing at both diagnosis and relapse. However, a peculiar Case, in complete remission of disease, displayed a total rescue of RNA editing at relapse, intriguingly suggesting ADAR2 activity/expression as a possible marker for long-term survival of patients with high-grade astrocytomas

  2. Postoperative irradiation of incompletely excised gemistocytic astrocytomas. Clinical outcome and prognostic factors

    International Nuclear Information System (INIS)

    Nowak-Sadzikowska, J.; Glinski, B.; Szpytma, T.; Pluta, E.

    2005-01-01

    Background and purpose: although gemistocytic astrocytomas are considered slow-growing tumors, they often behave aggressively and carry the least favorable prognosis among low-grade astrocytomas. The aim of this study is to evaluate the outcomes and prognostic factors of patients with incompletely excised gemistocytic astrocytomas irradiated postoperatively. Patients and methods: records of 48 patients with incompletely excised gemistocytic astrocytoma, irradiated between 1976 and 1998 at the department of radiation oncology, Maria Sklodowska-curie Memorial Cancer Center, Cracow, Poland, were reviewed. The total dose ranged from 50 to 60 Gy (mean: 59.35, median: 60 Gy) delivered in daily fractions of 2 Gy, 5 days a week. The treatment volume covered the residual tumor with a margin of 1-2 cm. Results: toxicity was acceptable. The overall actuarial survival rates at 5 and 10 years were 30% and 17%, respectively. Age and gender had an influence on overall survival by univariate and multivariate analysis (p < 0.05). Patients ≤ 35 years of age and female patients carried the best prognosis. Conclusion: in most patients with gemistocytic astrocytoma, combined surgery and postoperative radiotherapy result in only short-term survival. Older age is the most important unfavorable prognostic factor in patients with gemistocytic astrocytoma. (orig.)

  3. Prevention against diffuse spinal cord astrocytoma: can the Notch pathway be a novel treatment target?

    Directory of Open Access Journals (Sweden)

    Jian-jun Sun

    2015-01-01

    Full Text Available This study was designed to investigate whether the Notch pathway is involved in the development of diffuse spinal cord astrocytomas. BALB/c nude mice received injections of CD133 + and CD133− cell suspensions prepared using human recurrent diffuse spinal cord astrocytoma tissue through administration into the right parietal lobe. After 7-11 weeks, magnetic resonance imaging was performed weekly. Xenografts were observed on the surfaces of the brains of mice receiving the CD133 + cell suspension, and Notch-immunopositive expression was observed in the xenografts. By contrast, no xenografts appeared in the identical position on the surfaces of the brains of mice receiving the CD133− cell suspension, and Notch-immunopositive expression was hardly detected either. Hematoxylin-eosin staining and immunohistochemical staining revealed xenografts on the convex surfaces of the brains of mice that underwent CD133 + astrocytoma transplantation. Some sporadic astroglioma cells showed pseudopodium-like structures, which extended into the cerebral white matter. However, it should be emphasized that the subcortex xenograft with Notch-immunopositive expression was found in the fourth mouse received injection of CD133− astrocytoma cells. However, these findings suggest that the Notch pathway plays an important role in the formation of astrocytomas, and can be considered a novel treatment target for diffuse spinal cord astrocytoma.

  4. Pre-surgical integration of FMRI and DTI of the sensorimotor system in transcortical resection of a high-grade insular astrocytoma

    Directory of Open Access Journals (Sweden)

    Chelsea eEkstrand

    2016-03-01

    Full Text Available Herein we report on a patient with a WHO Grade III astrocytoma in the right insular region in close proximity to the internal capsule who underwent a right frontotemporal craniotomy. Total gross resection of insular gliomas remains surgically challenging based on the possibility of damage to the corticospinal tracts. However, maximizing the extent of resection has been shown to decrease future adverse outcomes. Thus, the goal of such surgeries should focus on maximizing extent of resection while minimizing possible adverse outcomes. In this case, pre-surgical planning included integration of functional magnetic resonance imaging (fMRI and diffusion tensor imaging (DTI, to localize motor and sensory pathways. Novel fMRI tasks were individually developed for the patient to maximize both somatosensory and motor activation simultaneously in areas in close proximity to the tumor. Information obtained was used to optimize resection trajectory and extent, facilitating gross total resection of the astrocytoma. Across all three motor-sensory tasks administered, fMRI revealed an area of interest just superior and lateral to the astrocytoma. Further, DTI analyses showed displacement of the corona radiata around the superior dorsal surface of the astrocytoma, extending in the direction of the activation found using fMRI. Taking into account these results, a transcortical superior temporal gyrus surgical approach was chosen in order to avoid the area of interest identified by fMRI and DTI. Total gross resection was achieved and minor post-surgical motor and sensory deficits were temporary. This case highlights the utility of comprehensive pre-surgical planning, including fMRI and DTI, to maximize surgical outcomes on a case-by-case basis.

  5. Analysis of difference of association between polymorphisms in the XRCC5, RPA3 and RTEL1 genes and glioma, astrocytoma and glioblastoma.

    Science.gov (United States)

    Jin, Tianbo; Wang, Yuan; Li, Gang; Du, Shuli; Yang, Hua; Geng, Tingting; Hou, Peng; Gong, Yongkuan

    2015-01-01

    Gliomas are the most common aggressive brain tumors and have many complex pathological types. Previous reports have discovered that genetic mutations are associated with the risk of glioma. However, it is unclear whether uniform genetic mutations exist difference between glioma and its two pathological types in the Han Chinese population. We evaluated 20 SNPs of 703 glioma cases (338 astrocytoma cases, 122 glioblastoma cases) and 635 controls in a Han Chinese population using χ(2) test and genetic model analysis. In three case-control studies, we found rs9288516 in XRCC5 gene showed a decreased risk of glioma (OR, 0.85; 95% CI, 0.73-0.99; P = 0.042) and glioblastoma (OR, 0.70; 95% CI, 0.52-0.92; P = 0.001) in the allele model. We identified rs414805 in RPA3 gene showed an increased risk of glioblastoma in allele model (OR, 1.38; 95% CI, 1.00-1.89; P = 0.047) and dominant model (OR, 1.57; 95% CI, 1.05-2.35; P = 0.027), analysis respectively. Meanwhile, rs2297440 in RTEL1 gene showed an increased risk of glioma (OR, 1.30; 95% CI, 1.10-1.54; P = 0.002) and astrocytoma (OR, 1.26; 95% CI, 1.02-1.54; P = 0.029) in the allele model. In addition, we also observed a haplotype of "GCT" in the RTEL1 gene with an increased risk of astrocytoma (P = 0.005). Polymorphisms in the XRCC5, RPA3 and RTEL1 genes, combinating with previous reaserches, are associated with glioma developing. However, those genes mutations may play different roles in the glioma, astrocytoma and glioblastoma, respectively.

  6. Evaluation of invasiveness of astrocytoma using 1H-magnetic resonance spectroscopy: correlation with expression of matrix metalloproteinase-2

    International Nuclear Information System (INIS)

    Zhang, Kai; Li, Chuanfu; Ma, Xiangxing; Meng, Xiangshui; Feng, Dechao; Liu, Ying; Li, Li

    2007-01-01

    Even low-grade astrocytomas infiltrate the entire brain, a feature that precludes their successful therapy. So to assess the invasive potential of astrocytoma is very important. The aim of this study was determine whether there is a significant correlation between the results of 1 H-magnetic resonance spectroscopy ( 1 H-MRS) and tumor invasive potential of astrocytoma, which is reflected by expression of matrix metalloproteinase-2 (MMP-2). The 1 H-MRS spectra of 41 histologically verified astrocytomas were obtained on a 3-T MR scanner. According to the World Health Organization classification criteria for central nervous system tumors, there were 16 low-grade astrocytomas (2 pilocytic astrocytomas, 14 grade II astrocytomas) and 25 high-grade astrocytomas (5 anaplastic astrocytomas, 20 glioblastomas).The choline/N-acetylaspartate (Cho/NAA) and choline/creatine (Cho/Cr) ratios were calculated. Of the 41 astrocytomas, 19 (8 low-grade and 11 high-grade) were analyzed immunohistochemically. Expression of MMP-2 was determined using streptavidin-peroxidase complex (SP) staining which was quantified by calculating its calibrated opacity density (COD) using an image analysis system. The correlations between metabolite ratios and the quantitative data from the immunohistochemical tests in the 19 astrocytomas were determined. The Cho/NAA and Cho/Cr ratios of high-grade astrocytoma were both significantly greater than those of low-grade astrocytoma (t = -6.222, P = 0.000; t = -6.533, P = 0.000, respectively). MMP-2 COD values of high-grade astrocytomas were also significantly greater than those of low-grade astrocytomas (t = -5.892, P 0.000). There were strong positive correlations between Cho/NAA ratio and MMP-2 COD (r = 0.669, P = 0.002), and between Cho/Cr ratio and MMP-2 COD (r = 0.689, P = 0.001). 1 H-MRS is helpful in evaluating the invasiveness of astrocytomas and predicting prognosis preoperatively by determining the Cho/NAA and Cho/Cr ratios. (orig.)

  7. Complement activation in astrocytomas: deposition of C4d and patient outcome

    International Nuclear Information System (INIS)

    Mäkelä, Katri; Helén, Pauli; Haapasalo, Hannu; Paavonen, Timo

    2012-01-01

    C4d is a cleavage product of complement component C4 and is considered to serve as a marker for the site of complement activation. In this study C4d staining of grade I-IV astrocytic tumors was studied to explore if there is an association between complement activation and the grade of tumor, or patient survival. Tissue micro-array samples of 102 astrocytomas were stained immunohistochemically. The material consisted of 9 pilocytic astrocytomas and 93 grade II-IV astrocytomas, of which 67 were primary resections and 26 recurrent tumors. The intensity of C4d staining as well as extent of C4d and CD34 staining were evaluated. The intensity of C4d staining was scored semiquantitatively. The extent of the staining was counted morphometrically with a point counting grid yielding a percent of C4d and CD34 positive area of the sample. The intensity and extent of C4d staining increased in grade II-IV diffusely infiltrating astrocytoma tumors in line with the malignancy grade (p = 0.034 and p = 0.016, respectively, Kruskal-Wallis test). However, C4d positive tumor area percentages were higher in grade I pilocytic astrocytomas than in grade II-IV diffusely infiltrating astrocytomas (p = 0.041, Mann–Whitney test). There was a significant correlation between CD34 positive and C4d positive endothelial area fraction in diffusely infiltrating astrocytomas (p < 0.001, Pearson correlation). In these tumors, the increasing intensity of C4d staining was also associated with worsened patient outcome (p = 0.014, log-rank test). The worsening of patient outcome and malignant progression of tumor cells seem to be connected to microenvironmental changes evoked by chronically activated complement

  8. Astrocytoma in the medulla oblongata diagnosed by magnetic resonance imaging

    International Nuclear Information System (INIS)

    Suga, Toshihiro; Takahashi, Shin-ichiro; Sonobe, Makoto; Koshu, Keiji; Hirota, Shigeru; Kawakami, Hiroshi; Fujii, Kyoichi; Namiki, Tsuneo.

    1987-01-01

    A 22-year-old male was admitted to Mito National Hospital with complaints of persistent, progressive dysphagia, hoarseness, and numbness over his entire body. Neurological examination showed bilateral 7th, 9th, and 10th nerve paralysis, tetraparesis, sensory disturbance of the whole body, and hyper-reflexia of all extremities. Pale, low-density areas in the medulla oblongata and upper cervical spinal cord were detected by conventional computed tomography. Magnetic resonance imaging (MRI) disclosed low-signal masses involving those areas and in the lower cervical cord. Suboccipital craniotomy exposed a solid, firm, well demarcated intramedullary tumor in the medulla oblongata. The tumor was removed en bloc and was histologically diagnosed as a pilocytic astrocytoma. The postoperative course was uneventful and the patient's symptoms improved dramatically. Postoperative MRI revealed no residual tumor in the medulla oblongata or upper cervical cord. This case illustrates the value of preoperative MRI, which precisely delineates the location and extent of the tumor and greatly facilitates direct surgery of the medulla oblongata. (author)

  9. Everolimus Alleviates Obstructive Hydrocephalus due to Subependymal Giant Cell Astrocytomas.

    Science.gov (United States)

    Moavero, Romina; Carai, Andrea; Mastronuzzi, Angela; Marciano, Sara; Graziola, Federica; Vigevano, Federico; Curatolo, Paolo

    2017-03-01

    Subependymal giant cell astrocytomas (SEGAs) are low-grade tumors affecting up to 20% of patients with tuberous sclerosis complex (TSC). Early neurosurgical resection has been the only standard treatment until few years ago when a better understanding of the molecular pathogenesis of TSC led to the use of mammalian target of rapamycin (mTOR) inhibitors. Surgical resection of SEGAs is still considered as the first line treatment in individuals with symptomatic hydrocephalus and intratumoral hemorrhage. We describe four patients with symptomatic or asymptomatic hydrocephalus who were successfully treated with the mTOR inhibitor everolimus. We collected the clinical data of four consecutive patients presenting with symptomatic or asymptomatic hydrocephalus due to a growth of subependymal giant cell atrocytomas and who could not undergo surgery for different reasons. All patients experienced a clinically significant response to everolimus and an early shrinkage of the SEGA with improvement in ventricular dilatation. Everolimus was well tolerated by all individuals. Our clinical series demonstrate a possible expanding indication for mTOR inhibition in TSC, which can be considered in patients with asymptomatic hydrocephalus or even when the symptoms already appeared. It offers a significant therapeutic alternative to individuals that once would have undergone immediate surgery. Everolimus might also allow postponement of a neurosurgical resection, making it elective with an overall lower risk. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Anaplastic astrocytoma 14 years after radiotherapy for pituitary adenoma

    International Nuclear Information System (INIS)

    Tamura, Masaru; Misumi, Syuuzou; Kurosaki, Syuuhei; Shibasaki, Takashi; Ohye, Chihiro

    1992-01-01

    A case of anaplastic astrocytoma following radiotherapy for growth hormone secreting pituitary adenoma is presented with a review of the literature. A 43 year old female was admitted with signs of acromegaly and hypertension. An eosinophilic pituitary adenoma was subtotally removed by transsphenoidal approach, followed by 60 Gy irradiation using a 2x2 cm lateral field. Fourteen years later at the age of 57, she suffered from headache, recent-memory disturbance and uncinate fits. CT scan and MRI disclosed ring-like enhanced mass lesion in the left temporal lobe, corresponding to the previous irradiated field. 18 F-FDG PET showed hypermetabolism at the lesion. Left frontotemporal craniotomy was performed, and a reddish gray gelatinous tumor containing necrotic center and cyst was partially removed. Histologically, the tumor consisted of hypercellular astrocytic cells with perivascular pseudorosette. Coagulation necrosis at the center of the tumor, and hyalinosis and fibrosis of the blood vessels in and around the tumor, which might have been caused by the antecedent radiotherapy, were recognized. Postoperative radiotherapy and chemotherapy, were given, however, she expired 13 months after the operation. Seven cases, including ours, of malignant glioma following radiotherapy for pituitary adenoma were reported in the literature. A total dose of irradiation varies from 45 to 95 Gy with a mean of 50 Gy. The period of latency before tumor occurrence ranges from 5 to 22 years with a mean of 10 years. The differentiation of radiation-induced gliomas from radionecrosis of the brain is also discussed. (author)

  11. Anaplastic astrocytoma 14 years after radiotherapy for pituitary adenoma

    Energy Technology Data Exchange (ETDEWEB)

    Tamura, Masaru; Misumi, Syuuzou; Kurosaki, Syuuhei; Shibasaki, Takashi; Ohye, Chihiro (Gunma Univ., Maebashi (Japan). School of Medicine)

    1992-04-01

    A case of anaplastic astrocytoma following radiotherapy for growth hormone secreting pituitary adenoma is presented with a review of the literature. A 43 year old female was admitted with signs of acromegaly and hypertension. An eosinophilic pituitary adenoma was subtotally removed by transsphenoidal approach, followed by 60 Gy irradiation using a 2x2 cm lateral field. Fourteen years later at the age of 57, she suffered from headache, recent-memory disturbance and uncinate fits. CT scan and MRI disclosed ring-like enhanced mass lesion in the left temporal lobe, corresponding to the previous irradiated field. {sup 18}F-FDG PET showed hypermetabolism at the lesion. Left frontotemporal craniotomy was performed, and a reddish gray gelatinous tumor containing necrotic center and cyst was partially removed. Histologically, the tumor consisted of hypercellular astrocytic cells with perivascular pseudorosette. Coagulation necrosis at the center of the tumor, and hyalinosis and fibrosis of the blood vessels in and around the tumor, which might have been caused by the antecedent radiotherapy, were recognized. Postoperative radiotherapy and chemotherapy, were given, however, she expired 13 months after the operation. Seven cases, including ours, of malignant glioma following radiotherapy for pituitary adenoma were reported in the literature. A total dose of irradiation varies from 45 to 95 Gy with a mean of 50 Gy. The period of latency before tumor occurrence ranges from 5 to 22 years with a mean of 10 years. The differentiation of radiation-induced gliomas from radionecrosis of the brain is also discussed. (author).

  12. PHAKOMATOSIS : INTRESTING CASES OF TUBEROUS SCLEROSIS WITH RETINAL ASTROCYTOMA

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao

    2015-05-01

    Full Text Available NTRODUCTION: Tuberous sclerosis complex (TSC or Morbus Bourneville - Pringle disease is an autosomal dominant phakomatosis, first described by Desiree - Magloire Bourneville in 1880. Tuberous sclerosis is a genetic disorder characterized by the growth of numerous benign tumours in many parts of the body caused by mutations on either of two genes, TSC1 and TSC2. This rare genetic disorder is usually associated with a triad of seizures, mental retardation and cutaneous lesions. Approximately one half of all patients affected by TS develop at least one retinal astrocytoma in one eye. PRESENTATION OF CASES: In the department of ophthalmology, G.S.L M edical C ollege, Rajahmundry, we came across 3 cases of tuberous sclerosis involving multi organ systems. Out of 3 cases, 2 cases were reported to be familial and 1case is sporadic, with a history of epilepsy with angiofibromatosis lesions over the face, multiple ash - leaf lesions over the abdomen, renal angiomyolipomas, multiple subependymal nodules in brain and retinal astrocytic hamartomas in the retina. CONCLUSION: It is important to be cognizant of the likely presence of systemic and ocular pathology in a child with mental retardation and skin lesions. Identification of retinal phakomatosis during ocular evaluation in any suspected case of Tuberous sclerosis can aid in the establishment of the diagnosis of the disease

  13. Geometrical study of astrocytomas through fractals and scaling analysis

    International Nuclear Information System (INIS)

    Torres H, F.; Baena N, R.; Vergara V, J.; Guerrero M, M.

    2017-10-01

    The tumor growth is a complex process characterized by the proliferation of uncontrollable cells which invade neighbor tissues. The understanding process of this type of phenomena is very relevant in order to establish diagnosis and proper therapy strategies and to start the valorization of its complexity with proper descriptors produced by the scaling analysis, which define the tumor growth geometry. In this work, obtained results through the scaling analysis for pilocytic astrocytomas, anaplastic and diffuse, are shown, which tumors of primary origin are. On them, it is calculated the fractal dimension and critic exponents of local roughness to characterize in vivo three-dimensional tumor growth. The acquisition of the images for this type of injuries was carried out according to the standard protocol used for brain radiotherapy and radiosurgery, i.e., axial, coronal and sagittal magnetic resonance T1 weighted images and comprising the brain volume for image registration. Image segmentation was performed by the application the K-means procedure upon contrasted images. The results show significant variations of the parameters depending on the tumor stage and its histological origin. (Author)

  14. Perceptual Robust Design

    DEFF Research Database (Denmark)

    Pedersen, Søren Nygaard

    The research presented in this PhD thesis has focused on a perceptual approach to robust design. The results of the research and the original contribution to knowledge is a preliminary framework for understanding, positioning, and applying perceptual robust design. Product quality is a topic...... been presented. Therefore, this study set out to contribute to the understanding and application of perceptual robust design. To achieve this, a state-of-the-art and current practice review was performed. From the review two main research problems were identified. Firstly, a lack of tools...... for perceptual robustness was found to overlap with the optimum for functional robustness and at most approximately 2.2% out of the 14.74% could be ascribed solely to the perceptual robustness optimisation. In conclusion, the thesis have offered a new perspective on robust design by merging robust design...

  15. Stereotactic Radiosurgery for Recurrent or Unresectable Pilocytic Astrocytoma

    Energy Technology Data Exchange (ETDEWEB)

    Hallemeier, Christopher L. [Department of Radiation Oncology, Mayo Clinic, Rochester, MN (United States); Pollock, Bruce E. [Department of Radiation Oncology, Mayo Clinic, Rochester, MN (United States); Department of Neurological Surgery, Mayo Clinic, Rochester, MN (United States); Schomberg, Paula J. [Department of Radiation Oncology, Mayo Clinic, Rochester, MN (United States); Link, Michael J. [Department of Neurological Surgery, Mayo Clinic, Rochester, MN (United States); Brown, Paul D. [Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Stafford, Scott L., E-mail: Stafford.scott@mayo.edu [Department of Radiation Oncology, Mayo Clinic, Rochester, MN (United States)

    2012-05-01

    Purpose: To report the outcomes in patients with recurrent or unresectable pilocytic astrocytoma (PA) treated with Gamma Knife stereotactic radiosurgery (SRS). Methods and Materials: Retrospective review of 18 patients (20 lesions) with biopsy-confirmed PA having SRS at our institution from 1992 through 2005. Results: The median patient age at SRS was 23 years (range, 4-56). Thirteen patients (72%) had undergone one or more previous surgical resections, and 10 (56%) had previously received external-beam radiation therapy (EBRT). The median SRS treatment volume was 9.1 cm{sup 3} (range, 0.7-26.7). The median tumor margin dose was 15 Gy (range, 12-20). The median follow-up was 8.0 years (range, 0.5-15). Overall survival at 1, 5, and 10 years after SRS was 94%, 71%, and 71%, respectively. Tumor progression (local solid progression, n = 4; local solid progression + distant, n = 1; distant, n = 2; cyst development/progression, n = 4) was noted in 11 patients (61%). Progression-free survival at 1, 5, and 10 years was 65%, 41%, and 17%, respectively. Prior EBRT was associated with inferior overall survival (5-year risk, 100% vs. 50%, p = 0.03) and progression-free survival (5-year risk, 71% vs. 20%, p = 0.008). Nine of 11 patients with tumor-related symptoms improved after SRS. Symptomatic edema after SRS occurred in 8 patients (44%), which resolved with short-term corticosteroid therapy in the majority of those without early disease progression. Conclusions: SRS has low permanent radiation-related morbidity and durable local tumor control, making it a meaningful treatment option for patients with recurrent or unresectable PA in whom surgery and/or EBRT has failed.

  16. Stereotactic Radiosurgery for Recurrent or Unresectable Pilocytic Astrocytoma

    International Nuclear Information System (INIS)

    Hallemeier, Christopher L.; Pollock, Bruce E.; Schomberg, Paula J.; Link, Michael J.; Brown, Paul D.; Stafford, Scott L.

    2012-01-01

    Purpose: To report the outcomes in patients with recurrent or unresectable pilocytic astrocytoma (PA) treated with Gamma Knife stereotactic radiosurgery (SRS). Methods and Materials: Retrospective review of 18 patients (20 lesions) with biopsy-confirmed PA having SRS at our institution from 1992 through 2005. Results: The median patient age at SRS was 23 years (range, 4–56). Thirteen patients (72%) had undergone one or more previous surgical resections, and 10 (56%) had previously received external-beam radiation therapy (EBRT). The median SRS treatment volume was 9.1 cm 3 (range, 0.7–26.7). The median tumor margin dose was 15 Gy (range, 12–20). The median follow-up was 8.0 years (range, 0.5–15). Overall survival at 1, 5, and 10 years after SRS was 94%, 71%, and 71%, respectively. Tumor progression (local solid progression, n = 4; local solid progression + distant, n = 1; distant, n = 2; cyst development/progression, n = 4) was noted in 11 patients (61%). Progression-free survival at 1, 5, and 10 years was 65%, 41%, and 17%, respectively. Prior EBRT was associated with inferior overall survival (5-year risk, 100% vs. 50%, p = 0.03) and progression-free survival (5-year risk, 71% vs. 20%, p = 0.008). Nine of 11 patients with tumor-related symptoms improved after SRS. Symptomatic edema after SRS occurred in 8 patients (44%), which resolved with short-term corticosteroid therapy in the majority of those without early disease progression. Conclusions: SRS has low permanent radiation-related morbidity and durable local tumor control, making it a meaningful treatment option for patients with recurrent or unresectable PA in whom surgery and/or EBRT has failed.

  17. Conformal proton radiation therapy for pediatric low-grade astrocytomas

    Energy Technology Data Exchange (ETDEWEB)

    Hug, E.B. [Loma Linda Univ. Medical Center, Loma Linda, CA (United States). Dept. of Radiation Medicine; Loma Linda Univ. Medical Center, Loma Linda, CA (United States). Dept. of Pediatrics and Dept. of Pathology; Darthmouth-Hitchcock Medical Center, Lebanon, New Hampshire (United States). Section of Radiation Oncology; Muenter, M.W.; Archambeau, J.O.; DeVries, A.; Loredo, L.N.; Grove, R.I.; Slater, J.D. [Loma Linda Univ. Medical Center, Loma Linda, CA (United States). Dept. of Radiation Medicine; Liwnicz, B. [Loma Linda Univ. Medical Center, Loma Linda, CA (United States). Dept. of Pathology

    2002-01-01

    Background: To evaluate the safety and efficacy of proton radiation therapy (PRT) for intracranial low-grade astrocytomas, the authors analyzed the first 27 pediatric patients treated at Loma Linda University Medical Center (LLUMC). Patients and Method: Between September 1991 and August 1997, 27 patients (13 female, 14 male) underwent fractionated proton radiation therapy for progressive or recurrent low-grade astrocytoma. Age at time of treatment ranged from 2 to 18 years (mean: 8.7 years). Tumors were located centrally (diencephatic) in 15 patients, in the cerebral and cerebellar hemispheres in seven patients, and in the brainstem in five patients. 25/27 patients (92%) were treated for progressive, unresectable, or residual disease following subtotal resection. Tissue diagnosis was available in 23/27 patients (85%). Four patients with optic pathway tumors were treated without histologic confirmation. Target doses between 50.4 and 63.0 CGE (cobalt gray equivalent, mean: 55.2 CGE) were prescribed at 1.8 CGE per fraction, five treatments per week. Results: At a mean follow-up period of 3.3 years (0.6-6.8 years), 6/27 patients experienced local failure (all located within the irradiated field), and 4/27 patients had died. By anatomic site these data translated into rates of local control and survival of 87% (13/15 patients) and 93% (14/15 patients) for central tumors, 71% (5/7 patients) and 86% (6/7 patients) for hemispheric tumors, and 60% (3/5 patients) and 60% (3/5 patients) for tumors located in the brainstem. Proton radiation therapy was generally well tolerated. All children with local control maintained their performance status. One child with associated neurofibromatosis, Type 1, developed Moyamoya disease. All six patients with optic pathway tumors and useful vision maintained or improved their visual status. Conclusions: This report on pediatric low-grade astrocytomas confirms proton radiation therapy as a safe and efficacious 3-D conformal treatment

  18. Association of invasive breast carcinoma and multicentric high grade astrocytoma: a case report with a review.

    Science.gov (United States)

    Pour, P Hossein; Forouzandeh, M; Beni, A Naderi; Beni, Z Naderi; Hoseinpour, P

    2011-03-01

    Breast cancer is the most common cancer in women. Multicentric gliomas are uncommon lesions of the central nervous system (CNS) with an unprecise rate of occurrence that diffusely infiltrate large portions of the brain. High grade astrocytoma is the most agressive form of gliomas and often has a distinct neuroimaging pattern with a poor prognosis. We report a case of a 29-year-old woman patient with primary breast carcinoma and high grade astrocytoma subsequently developed. The woman was treated by mastectomy and 20 months post-diagnosis of the cancer she exhibited a transient facial paralysis. Magnetic resonance imaging (MRI) revealed two cranial masses suspicious of metastasis. A complete tumor removal from the brain was performed. On histological examination, this tumor was a high grade astrocytoma.

  19. Rab23 is overexpressed in human astrocytoma and promotes cell migration and invasion through regulation of Rac1.

    Science.gov (United States)

    Wang, Minghao; Dong, Qianze; Wang, Yunjie

    2016-08-01

    Rab23 overexpression has been implicated in several human cancers. However, its biological roles and molecular mechanism in astrocytoma have not been elucidated. The aim of this study is to explore clinical significance and biological roles of Rab23 in astrocytoma. We observed negative Rab23 staining in normal astrocytes and positive staining in 39 out of 86 (45 %) astrocytoma specimens using immunohistochemistry. The positive rate of Rab23 was higher in grades III and IV (56.5 %, 26/46) than grades I + II astrocytomas (32.5 %, 13/40, p Rac1 activity. Treatment of transfected cells with a Rac1 inhibitor decreased Rac1 activity and invasion. In conclusion, Rab23 serves as an important oncoprotein in human astrocytoma by regulating cell invasion and migration through Rac1 activity.

  20. Genomic Deletions Correlate with Underexpression of Novel Candidate Genes at Six Loci in Pediatric Pilocytic Astrocytoma

    Directory of Open Access Journals (Sweden)

    Nicola Potter

    2008-08-01

    Full Text Available The molecular pathogenesis of pediatric pilocytic astrocytoma (PA is not well defined. Previous cytogenetic and molecular studies have not identified nonrandom genetic aberrations. To correlate differential gene expression and genomic copy number aberrations (CNAs in PA, we have used Affymetrix GeneChip HG_U133A to generate gene expression profiles of 19 pediatric patients and the SpectralChip 2600 to investigate CNAs in 11 of these tumors. Hierarchical clustering according to expression profile similarity grouped tumors and controls separately. We identified 1844 genes that showed significant differential expression between tumor and normal controls, with a large number clearly influencing phosphatidylinositol and mitogen-activated protein kinase signaling in PA. Most CNAs identified in this study were single-clone alterations. However, a small region of loss involving up to seven adjacent clones at 7q11.23 was observed in seven tumors and correlated with the underexpression of BCL7B. Loss of four individual clones was also associated with reduced gene expression including SH3GL2 at 9p21.2-p23, BCL7A (which shares 90% sequence homology with BCL7B at 12q24.33, DRD1IP at 10q26.3, and TUBG2 and CNTNAP1 at 17q21.31. Moreover, the down-regulation of FOXG1B at 14q12 correlated with loss within the gene promoter region in most tumors. This is the first study to correlate differential gene expression with CNAs in PA.

  1. Robustness of Structural Systems

    DEFF Research Database (Denmark)

    Canisius, T.D.G.; Sørensen, John Dalsgaard; Baker, J.W.

    2007-01-01

    The importance of robustness as a property of structural systems has been recognised following several structural failures, such as that at Ronan Point in 1968,where the consequenceswere deemed unacceptable relative to the initiating damage. A variety of research efforts in the past decades have...... attempted to quantify aspects of robustness such as redundancy and identify design principles that can improve robustness. This paper outlines the progress of recent work by the Joint Committee on Structural Safety (JCSS) to develop comprehensive guidance on assessing and providing robustness in structural...... systems. Guidance is provided regarding the assessment of robustness in a framework that considers potential hazards to the system, vulnerability of system components, and failure consequences. Several proposed methods for quantifying robustness are reviewed, and guidelines for robust design...

  2. Prognostic relevance of gemistocytic grade II astrocytoma: gemistocytic component and MR imaging features compared to non-gemistocytic grade II astrocytoma

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Young Jin [Inje University, Busan Paik Hospital, Department of Radiology, Busan (Korea, Republic of); Park, Ji Eun; Kim, Ho Sung; Lee, Ji Ye; Jung, Seung Chai; Choi, Choong Gon; Kim, Sang Joon [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Nam, Soo Jeong [University of Ulsan College of Medicine, Asan Medical Center, Department of Pathology, Seoul (Korea, Republic of)

    2017-07-15

    To determine if gemistocytic grade II astrocytoma (GemA) and its MR imaging characteristics are associated with a shorter time-to-progression (TTP) compared with non-gemistocytic grade II astrocytoma (non-GemA). We enrolled 78 patients who were followed up more than 5 years (29 pathologically proven GemA and 49 non-GemA) during a 10-year period. Contrast-enhanced T1-weighted, diffusion-weighted imaging (DWI), dynamic susceptibility contrast (DSC), and MR spectroscopy (MRS) and clinical data were retrospectively reviewed. Clinical and MR imaging features were analyzed as possible prognostic factors of high-grade transformation, and multivariate analysis of TTP was performed using Cox proportional modeling. GemA showed more frequent high-grade features than non-GemA, including diffusion restriction (P <.001), increased choline/creatine (P =.02), and increased choline/NAA ratio (P =.015). Patients with GemA had a significantly shorter median TTP (53.1 vs 68 months; P <.001). A gemistocytic histopathology (hazard ratio = 3.42; P =.015) and low ADC (hazard ratio = 3.61; P =.001) were independently associated with a shorter TTP. GemA can present with MR imaging findings mimicking high-grade glioma at initial diagnosis and transforms to high-grade disease earlier than non-GemA. Low ADC on DWI might be useful in stratifying the risk of progression in patients with grade II astrocytoma. (orig.)

  3. Clinical Implications of the Epidermal Growth Factor Receptor overexpression in the High-grade Astrocytomas

    International Nuclear Information System (INIS)

    Hong, Seong Eon; Kang, Jin Oh; Lee, Hye Kyoung; Yang, Moon Ho; Leem, Won; Cho, Kyung Sam

    1996-01-01

    To determine the incidence and prognostic effects of EGFR overexpression in the high-grade astrocytomas. With 23 paraffin blocks of the high-garde astrocytomas, expression of EGFR were evaluated by immunohistochemical staining employing polyclonal antibody raised to short cytoplasmic domain of the molecule. Two out of 7 anaplastic astrocytomas and 9 out of 16 glioblastoma multiform patients showed overexpression of EGFR(p=0.44). Three out of 11 patients of age below 55 and 8 out of 12 patients of age over 54 showed EGFR overexpression(p=0.141). Median survival of the EGFR negative anaplastic astrocytoma patient was 37 months. Median survival of the glioblastoma multiform patients were 11 months in EGFR negative group and 7 months in EGFR positive group. But survival difference was not significant(p=0.17). There was a marked trend of increasing overexpression of EGFR in older patients. But survival of the glioblastoma multiform decreased by the overexpression of the EGFR without significant

  4. Clinical significance of changes of serum expression of IGF-I in patients with astrocytoma

    International Nuclear Information System (INIS)

    Liu Jianbo; Ding Dongmei; Yang Fubing

    2005-01-01

    Objective: To investigate the serum expression of IGF-I in patients with astrocytoma of different degrees of malignancy as well as the changes of levels after operative removal of the tumor. Methods: Serum IGF-I contents were measured with IRMA in 16 patients with Grade I-II astrocytoma and 14 patients with Grade III-IV astrocytoma both before and after operation as well as in 30 controls. Results: The serum contents of IGF-I in both groups of patients were significantly higher than those in controls (P<0.05). The levels in Grade III-IV patients were significantly higher than those in Grade I-II patients (P < 0.05 ). After operation, the levels dropped significantly (vs before operation, P<0.05). Conclusion: The serum contents of IGF - I in patients with astrocytoma were positively correlated with the degree of malignancy. Post-operative decrease of IGF-I contents was related to the decrease of tumor burden. (authors)

  5. Sustained response to weekly vinblastine in 2 children with pilomyxoid astrocytoma associated with diencephalic syndrome.

    Science.gov (United States)

    Singh, Gurpreet; Wei, Xing Chang; Hader, Walter; Chan, Jennifer A; Bouffet, Eric; Lafay-Cousin, Lucie

    2013-03-01

    Diencephalic syndrome (DS) related to hypothalamic/chiasmatic region tumor has mainly been reported with low-grade glioma. We described 2 young children with DS related to pilomyxoid astrocytoma. Despite the recognized more agressive clinical behavior of this histologic subtype, we report successful resolution of DS and sustained tumor response with prolonged use of single-agent vinblastine.

  6. Tumour vasculature and angiogenic profile of paediatric pilocytic astrocytoma; is it much different from glioblastoma?

    NARCIS (Netherlands)

    Sie, M.; de Bont, E. S. J. M.; Scherpen, F. J. G.; Hoving, E. W.; den Dunnen, W. F. A.

    2010-01-01

    Aims: Pilocytic astrocytomas are the most frequent brain tumours in children. Because of their high vascularity, this study aimed to obtain insights into potential angiogenic related therapeutic targets in these tumours by characterization of the vasculature and the angiogenic profile. In this study

  7. Robust procedures in chemometrics

    DEFF Research Database (Denmark)

    Kotwa, Ewelina

    properties of the analysed data. The broad theoretical background of robust procedures was given as a very useful supplement to the classical methods, and a new tool, based on robust PCA, aiming at identifying Rayleigh and Raman scatters in excitation-mission (EEM) data was developed. The results show...

  8. Ammonium-induced calcium mobilization in 1321N1 astrocytoma cells

    International Nuclear Information System (INIS)

    Hillmann, Petra; Koese, Meryem; Soehl, Kristina; Mueller, Christa E.

    2008-01-01

    High blood levels of ammonium/ammonia (NH 4 + /NH 3 ) are associated with severe neurotoxicity as observed in hepatic encephalopathy (HE). Astrocytes are the main targets of ammonium toxicity, while neuronal cells are less vulnerable. In the present study, an astrocytoma cell line 1321N1 and a neuroblastoma glioma hybrid cell line NG108-15 were used as model systems for astrocytes and neuronal cells, respectively. Ammonium salts evoked a transient increase in intracellular calcium concentrations ([Ca 2+ ] i ) in astrocytoma (EC 50 = 6.38 mM), but not in NG108-15 cells. The ammonium-induced increase in [Ca 2+ ] i was due to an intracellular effect of NH 4 + /NH 3 and was independent of extracellular calcium. Acetate completely inhibited the ammonium effect. Ammonium potently reduced calcium signaling by G q protein-coupled receptors (H 1 and M3) expressed on the cells. Ammonium (5 mM) also significantly inhibited the proliferation of 1321N1 astrocytoma cells. While mRNA for the mammalian ammonium transporters RhBG and RhCG could not be detected in 1321N1 astrocytoma cells, both transporters were expressed in NG108-15 cells. RhBG and RhBC in brain may promote the excretion of NH 3 /NH 4 + from neuronal cells. Cellular uptake of NH 4 + /NH 3 was mainly by passive diffusion of NH 3 . Human 1321N1 astrocytoma cells appear to be an excellent, easily accessible human model for studying HE, which can substitute animal studies, while NG108-15 cells may be useful for investigating the role of the recently discovered Rhesus family type ammonium transporters in neuronal cells. Our findings may contribute to the understanding of pathologic ammonium effects in different brain cells, and to the treatment of hyperammonemia

  9. First results of the radiological surveillance of RIT trial for high grade astrocytomas in Cuba

    Energy Technology Data Exchange (ETDEWEB)

    Amador Balbona, Z.H.; Pardo Ayra, F.E.; Torres Berdeguez, M.B. [Isotope Centre, Havana (Cuba). Radiation Protection Dept.

    2004-07-01

    The first phase of the clinical trial using the humanized monoclonal antibody h-R3 labeled with {sup 188} Re, for radioimmunotherapy (RIT) of brain tumors began in the Republic of Cuba in 2002. This monoclonal antibody was obtained in the country and it is required to evaluate its toxicity, biodistribution and internal radiation dosimetry. Five groups of three patients of each one with an administered activity from 0.37 GBq to 1.1 GBq, are considered. The aim of this work is to assess workers doses and public doses for this research and to compare projected doses with the first results related to the radiological surveillance. The contribution to the total effective dose and equivalent dose in extremities are calculated with the code Microshield version 4.0 by each activity level, operation and total quantity of patients. We take into account radioactive decay of {sup 188} Re and consider that only a person made all of the operations during this study. It is demonstrated that individual doses are acceptable and lower than world average effective annual dose of natural radiation background (2.4 mSv), because for the operations of more risk are used individual protection means. Nevertheless, it is identified that nurses are the most exposed. The projected maximum equivalent dose to hands is about 4 mSv and it belongs to the neurosurgeon. Radiological surveillance is performed to verify our calculations. Five workers and public (four individuals) are monitoring for each patient with direct reading dosimeters DOSICARD and TLD for extremities. For the first seven patients results are obtained. The conservative assumptions in the dose assessment and the compliance with established safety procedures determine that the registered doses are lower than those were projected. RIT with 188 Re for high-grade astrocytomas is a safety practice from radiation protection point of view. There is not a reference of a similar study in Latin America. (author)

  10. First results of the radiological surveillance of RIT trial for high grade astrocytomas in Cuba

    International Nuclear Information System (INIS)

    Amador Balbona, Z.H.; Pardo Ayra, F.E.; Torres Berdeguez, M.B.

    2004-01-01

    The first phase of the clinical trial using the humanized monoclonal antibody h-R3 labeled with 188 Re, for radioimmunotherapy (RIT) of brain tumors began in the Republic of Cuba in 2002. This monoclonal antibody was obtained in the country and it is required to evaluate its toxicity, biodistribution and internal radiation dosimetry. Five groups of three patients of each one with an administered activity from 0.37 GBq to 1.1 GBq, are considered. The aim of this work is to assess workers doses and public doses for this research and to compare projected doses with the first results related to the radiological surveillance. The contribution to the total effective dose and equivalent dose in extremities are calculated with the code Microshield version 4.0 by each activity level, operation and total quantity of patients. We take into account radioactive decay of 188 Re and consider that only a person made all of the operations during this study. It is demonstrated that individual doses are acceptable and lower than world average effective annual dose of natural radiation background (2.4 mSv), because for the operations of more risk are used individual protection means. Nevertheless, it is identified that nurses are the most exposed. The projected maximum equivalent dose to hands is about 4 mSv and it belongs to the neurosurgeon. Radiological surveillance is performed to verify our calculations. Five workers and public (four individuals) are monitoring for each patient with direct reading dosimeters DOSICARD and TLD for extremities. For the first seven patients results are obtained. The conservative assumptions in the dose assessment and the compliance with established safety procedures determine that the registered doses are lower than those were projected. RIT with 188 Re for high-grade astrocytomas is a safety practice from radiation protection point of view. There is not a reference of a similar study in Latin America. (author)

  11. Spontaneous regression of residual low-grade cerebellar pilocytic astrocytomas in children

    International Nuclear Information System (INIS)

    Gunny, Roxana S.; Saunders, Dawn E.; Hayward, Richard D.; Phipps, Kim P.; Harding, Brian N.

    2005-01-01

    Cerebellar low-grade astrocytomas (CLGAs) of childhood are benign tumours and are usually curable by surgical resection alone or combined with adjuvant radiotherapy. To undertake a retrospective study of our children with CLGA to determine the optimum schedule for surveillance imaging following initial surgery. In this report we describe the phenomenon of spontaneous regression of residual tumour and discuss its prognostic significance regarding future imaging. A retrospective review was conducted of children treated for histologically proven CLGA at Great Ormond Street Hospital from 1988 to 1998. Of 83 children with CLGA identified, 13 (15.7%) had incomplete resections. Two children with large residual tumours associated with persistent symptoms underwent additional treatment. Eleven children were followed by surveillance imaging alone for a mean of 6.83 years (range 2-13.25 years). Spontaneous tumour regression was seen in 5 (45.5%) of the 11 children. There were no differences in age, gender, symptomatology, histological grade or Ki-67 fractions between those with spontaneous tumour regression and those with progression. There was a non-significant trend that larger volume residual tumours progressed. Residual tumour followed by surveillance imaging may either regress or progress. For children with residual disease we recommend surveillance imaging every 6 months for the first 2 years, every year for years 3, 4 and 5, then every second year if residual tumour is still present 5 years after initial surgery. This would detect not only progressive or recurrent disease, but also spontaneous regression which can occur later than disease progression. (orig.)

  12. Value of 18F-3,4-dihydroxyphenylalanine PET/MR image fusion in pediatric supratentorial infiltrative astrocytomas: a prospective pilot study.

    Science.gov (United States)

    Morana, Giovanni; Piccardo, Arnoldo; Milanaccio, Claudia; Puntoni, Matteo; Nozza, Paolo; Cama, Armando; Zefiro, Daniele; Cabria, Massimo; Rossi, Andrea; Garrè, Maria Luisa

    2014-05-01

    Infiltrative astrocytomas (IAs) represent a group of astrocytic gliomas ranging from low-grade to highly malignant, characterized by diffuse invasion of the brain parenchyma. When compared with their adult counterpart, pediatric IAs may be considered biologically distinct entities; nevertheless, similarly to those in adults they represent a complex oncologic challenge. The aim of this study was to investigate the diagnostic role, clinical contribution, and prognostic value of fused (18)F-3,4-dihydroxyphenylalanine ((18)F-DOPA) PET/MR images in pediatric supratentorial IAs. Pediatric patients with supratentorial IAs involving at least 2 cerebral lobes, either newly diagnosed or with suspected disease progression, prospectively underwent (18)F-DOPA PET and conventional MR imaging, performed within 10 d of each other. (18)F-DOPA PET data were interpreted qualitatively and semiquantitatively, fusing images with MR images. PET scans were classified as positive if tumors identified on MR imaging exhibited tracer uptake above the level of the corresponding contralateral normal brain. Maximum standardized uptake values, tumor-to-normal contralateral tissue ratios, and tumor-to-normal striatum ratios were calculated for all tumors. Correlations between the degree and extent of (18)F-DOPA uptake, MR imaging tumor characteristics, and histologic results were investigated. The contribution of (18)F-DOPA PET/MR image fusion was considered relevant if it enabled one to select the most appropriate biopsy site, discriminate between disease progression and treatment-related changes, or influence treatment strategy. The patient's outcome was finally correlated with (18)F-DOPA uptake. Thirteen patients (8 boys and 5 girls) were included (5 diffuse astrocytomas, 2 anaplastic astrocytomas, 5 gliomatosis cerebri, and 1 glioblastoma multiforme). The (18)F-DOPA uptake pattern was heterogeneous in all positive scans (9/13), revealing metabolic heterogeneities within each tumor. Significant

  13. Treatment results of non-pilocytic cerebral astrocytomas in adults treated by surgery, radiation therapy and chemotherapy

    International Nuclear Information System (INIS)

    Matsutani, Masao; Nishikawa, Ryo; Sugiyama, Satoshi; Fujimaki, Takamitsu; Nakamura, Osamu

    1999-01-01

    Non-pilocytic cerebral astrocytomas in adults are oncopathologically defined as well-differentiated carcinoma of the brain. They grow invasively and can not be cured by extensive surgery followed by radiation therapy. We performed multidisciplinary treatments consisting of surgery, radiation therapy and chemotherapy in 26 adult patients with non-pilocytic cerebral astrocytomas. The 5- and 10-year survival rates of the patients were 90.9% and 75.6%, respectively; these were better than reported survival rates of patients treated by postoperative radiation therapy alone. Precise analysis of clinical findings of astrocytic tumors suggested that glioblastomas growing superficially might be derived from preexisting astrocytomas. This hypothesis proposes that multidisciplinary treatments for astrocytomas in early stages could cure the disease and could ultimately decrease a number of glioblastomas. (author)

  14. Vascular endothelial growth factor and basic fibroblast growth factor expression positively correlates with angiogenesis and peritumoural brain oedema in astrocytoma

    International Nuclear Information System (INIS)

    Jang, F.F.; Wei, W.

    2008-01-01

    Astrocytoma is the most malignant intracranial neoplasm and is characterized by high neovascularization and peritumoural brain oedema. Angiogenesis is a complicated process in oncogenesis regulated by the balance between angiogenic and antiangiogenic factors. The expression of two angiogenic growth factors, vascular endothelial growth factor and basic fibroblast growth factor were investigated using immunohistochemistry for astrocytoma from 82 patients and 11 normal human tissues. The expression of vascular endothelial growth factor and basic fibroblast growth factor positively correlate with the pathological grade of astrocytoma, microvessel density numbers and brain oedema, which may be responsible for the increased tumour neovascularization and peritumoural brain oedema. The results support the idea that inhibiting vascular endothelial growth factor and basic fibroblast growth factor are useful for the treatment of human astrocytoma and to improve patient's clinical outcomes and prognosis. (author)

  15. Low-Grade Astrocytoma Associated with Abscess Formation: Case Report and Literature Review

    Directory of Open Access Journals (Sweden)

    Tai-Hsin Tsai

    2008-05-01

    Full Text Available A rare case of low-grade astrocytoma associated with abscess formation occurred in a 52-year-old man presenting with Broca's aphasia. He underwent craniotomy and tumor removal under the impression of brain tumor with necrotic cystic change. Abscess accumulation within the intra-axial tumor was found intraoperatively. Literature related to brain abscess with brain tumor is reviewed, with an emphasis on abscesses with astrocytoma. We discuss the common brain tumors that are associated with abscess, pathogens that coexist with brain tumor, and the pathogeneses of coexisting brain abscess and tumor. It is very important to know how to differentiate between and diagnose a brain abscess and tumor, or brain abscess with tumor, preoperatively from clinical presentation and through the use of computed tomography, conventional magnetic resonance imaging, diffusion-weighted imaging or magnetic resonance spectroscopy.

  16. Gemistocytic astrocytoma in the spinal cord in a dog: a case report

    Directory of Open Access Journals (Sweden)

    R.O. Chaves

    2016-08-01

    Full Text Available ABSTRACT This paper reports a case of a rare variant of the cervical spinal cord astrocytoma diagnosed in a dog with progressive neurological signs, initially asymmetrical, not ambulatory tetraparesis, segmental reflexes and normal muscle tone in all four limbs and absence of pain upon palpation of the cervical spine. Myelography revealed attenuation of the ventral and dorsal contrast line in the third region of the fifth cervical vertebra. At necropsy intramedullary cylindrical mass that stretched from the third to the sixth cervical vertebra, which replaced all the gray matter of the spinal cord was observed. In the histological study, there was the replacement of the substance by neoplastic cells mantle arranged loosely. The cells were large and slightly rounded. The eosinophilic cytoplasm was well defined, sometimes forming processes interconnecting cells. The nucleus was eccentric, round, oval or kidney-shaped, and the nucleolus was evident. Thus, the microscopic changes observed in the cervical spinal cord were consistent with gemistocytic astrocytoma.

  17. RNA-ID, a highly sensitive and robust method to identify cis-regulatory sequences using superfolder GFP and a fluorescence-based assay.

    Science.gov (United States)

    Dean, Kimberly M; Grayhack, Elizabeth J

    2012-12-01

    We have developed a robust and sensitive method, called RNA-ID, to screen for cis-regulatory sequences in RNA using fluorescence-activated cell sorting (FACS) of yeast cells bearing a reporter in which expression of both superfolder green fluorescent protein (GFP) and yeast codon-optimized mCherry red fluorescent protein (RFP) is driven by the bidirectional GAL1,10 promoter. This method recapitulates previously reported progressive inhibition of translation mediated by increasing numbers of CGA codon pairs, and restoration of expression by introduction of a tRNA with an anticodon that base pairs exactly with the CGA codon. This method also reproduces effects of paromomycin and context on stop codon read-through. Five key features of this method contribute to its effectiveness as a selection for regulatory sequences: The system exhibits greater than a 250-fold dynamic range, a quantitative and dose-dependent response to known inhibitory sequences, exquisite resolution that allows nearly complete physical separation of distinct populations, and a reproducible signal between different cells transformed with the identical reporter, all of which are coupled with simple methods involving ligation-independent cloning, to create large libraries. Moreover, we provide evidence that there are sequences within a 9-nt library that cause reduced GFP fluorescence, suggesting that there are novel cis-regulatory sequences to be found even in this short sequence space. This method is widely applicable to the study of both RNA-mediated and codon-mediated effects on expression.

  18. FLAIR MR sequence in the diagnosis and follow-up of low-grade astrocytomas

    Directory of Open Access Journals (Sweden)

    Stošić-Opinćal Tatjana

    2005-01-01

    Full Text Available Aim. To evaluate the sensitivity of fluid-attenuated inversion recovery (FLAIR sequence in the diagnosis and follow-up of the patients with low-grade astrocytomas compared with T2-weighted (T2W sequence. Methods. Twenty-four patients with biopsy- confirmed low-grade astrocytoma (age range, 15-66 years underwent T1- weighted (T1W, T2W and FLAIR imaging with a superconducting unit 1.0 T. FLAIR images were qualitatively evaluated by comparison with T2W images by the three experienced neuroradiologists. To evaluate the diagnostic value of FLAIR, the neuroradiologists individually assessed the possibilities of the detection of lesions, as well as the possibilities of the differentiation of tumor from the surrounding edema on FLAIR vs. T2W images. Every examiner ranked FLAIR sequence vs. T2W in three degrees: worse, equal and better. Results. The comparison of FLAIR with T2W spin-echo (SE images with regard to the detection of the lesions showed that 82.8% of FLAIR studies were superior, 17.2% were of similar diagnostic value, and none was inferior to the T2W images. The comparison of images with regard to the differentiation of tumor boundaries vs. surrounding edema showed that 92.5% of FLAIR studies were superior, 7.5% were of similar diagnostic value, and none was inferior to the T2W images. Conclusion. Our results were similar to the previous studies' results concerning the advantages of FLAIR sequence in the diagnosis of low grade astrocytomas over T2W sequence. FLAIR was better at showing different tumor components, and at distinguishing CSF from the cystic component, and the postoperative cavity, compared with T2W images. Our conclusion was that FLAIR could be routinely used in the evaluation and follow-up of low-grade astrocytomas.

  19. MR Findings of Desmoplastic Cerebral Astrocytoma of Infancy. A case report

    International Nuclear Information System (INIS)

    Kim, J.H.; Kim, I.O.; Kim, W.S.; Kim, K.H.; Park, C. M.; Yeon, K.M.

    2003-01-01

    Desmoplastic cerebral astrocytoma of infancy (DCAI) presents as a large supratentorial mass consisting of a central cystic component and an enhancing solid component associated with peripheral dural attachment. We report the unusual MR findings of a DCAI that differed from previously reported cases in terms of the presence of calcification, which is not considered a feature of this tumor, and the absence of an enhancing peripheral dural component

  20. Exposure to 60-Hz magnetic fields and proliferation of human astrocytoma cells in vitro.

    Science.gov (United States)

    Wei, M; Guizzetti, M; Yost, M; Costa, L G

    2000-02-01

    Epidemiological studies have suggested that exposure to electric and magnetic fields (EMF) may be associated with an increased incidence of brain tumors, most notably astrocytomas. However, potential cellular or molecular mechanisms involved in these effects of EMF are not known. In this study we investigated whether exposure to 60-Hz sinusoidal magnetic fields (0.3-1.2 G for 3-72 h) would cause proliferation of human astrocytoma cells. Sixty-Hertz magnetic fields (MF) caused a time- and dose-dependent increase in proliferation of astrocytoma cells, measured by (3)H-thymidine incorporation and by flow cytometry, and strongly potentiated the effect of two agonists (the muscarinic agonist carbachol and the phorbol ester PMA). However, MF had no effect on DNA synthesis of rat cortical astrocytes, i.e., of similar, nontransformed cells. To determine the amount of heating induced by MF, temperatures were also recorded in the medium. Both 1.2 G MF and a sham exposure caused a 0.7 degrees C temperature increase in the medium; however, (3)H-thymidine incorporation induced by sham exposure was significantly less than that caused by MF. GF 109203X, a rather specific protein kinase C (PKC) inhibitor, and down-regulation of PKC inhibited the effect of MF on basal and on agonist-stimulated (3)H-thymidine incorporation. These data indicate that MF can increase the proliferation of human astrocytoma cells and strongly potentiate the effects of two agonists. These findings may provide a biological basis for the observed epidemiological associations between MF exposure and brain tumors. Copyright 2000 Academic Press.

  1. An acid phosphatase in the plasma membranes of human astrocytoma showing marked specificity toward phosphotyrosine protein.

    OpenAIRE

    Leis, J F; Kaplan, N O

    1982-01-01

    The plasma membrane from the human tumor astrocytoma contains an active acid phosphatase activity based on hydrolysis of p-nitrophenyl phosphate. Other acid phosphatase substrates--beta-glycerophosphate, O-phosphorylcholine, and 5'-AMP--are not hydrolyzed significantly. The phosphatase activity is tartrate insensitive and is stimulated by Triton X-100 and EDTA. Of the three known phosphoamino acids, only free O-phosphotyrosine is hydrolyzed by the membrane phosphatase activity. Other acid pho...

  2. Supratentorial juvenile pilocytic astrocytoma in a young adult with Silver-Russell syndrome.

    LENUS (Irish Health Repository)

    Fenton, E

    2008-12-01

    Silver-Russell syndrome is a rare genetically heterogeneous disorder in which patients demonstrate intrauterine and postnatal growth retardation, triangular facies, excessive sweating during early childhood, late closure of the anterior fontanelle and skeletal asymmetry. An association with malignancy exists and only one previous intracranial tumour has been reported, a craniopharyngioma. We report the first case of Silver-Russell syndrome associated with a supratentorial juvenile pilocytic astrocytoma.

  3. MRS of pilocytic astrocytoma: The peak at 2 ppm may not be NAA.

    Science.gov (United States)

    Tamrazi, Benita; Nelson, Marvin D; Blüml, Stefan

    2017-08-01

    To determine whether the chemical shift of residual N-acetylaspartate (NAA) signal in pilocytic astrocytomas (PA) is consistent with the position of the NAA peak in controls. MR spectra from 27 pediatric World Health Organization (WHO) grade I pilocytic astrocytoma patients, fifteen patients with WHO grade II and high-grade (III-IV) astrocytomas, and 36 controls were analyzed. All spectra were acquired with a short echo time (35 ms), single voxel point-resolved spectroscopy sequence on clinical 3 tesla scanners. Fully automated LCModel software was used for processing, which included the fitting of peak positions for NAA and creatine (Cr). The chemical shift difference between the NAA and Cr peaks was significantly smaller (by 0.016 ± 0.005 parts per million, P NAA peak in PAs is not consistent with NAA. The signal likely originates from an N-acetyl group of one or more other chemicals such as N-acetylated sugars. Magn Reson Med 78:452-456, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  4. Xenograft transplantation of human malignant astrocytoma cells into immunodeficient rats: an experimental model of glioblastoma.

    Science.gov (United States)

    Miura, Flávio Key; Alves, Maria Jose Ferreira; Rocha, Mussya Cisotto; da Silva, Roseli; Oba-Shinjo, Sueli Mieko; Marie, Suely Kazue Nagahashi

    2010-03-01

    Astrocytic gliomas are the most common intracranial central nervous system neoplasias, accounting for about 60% of all primary central nervous system tumors. Despite advances in the treatment of gliomas, no effective therapeutic approach is yet available; hence, the search for a more realistic model to generate more effective therapies is essential. To develop an experimental malignant astrocytoma model with the characteristics of the human tumor. Primary cells from subcutaneous xenograft tumors produced with malignant astrocytoma U87MG cells were inoculated intracerebrally by stereotaxis into immunosuppressed (athymic) Rowett rats. All four injected animals developed non-infiltrative tumors, although other glioblastoma characteristics, such as necrosis, pseudopalisading cells and intense mitotic activity, were observed. A malignant astrocytoma intracerebral xenograft model with poorly invasive behavior was achieved in athymic Rowett rats. Tumor invasiveness in an experimental animal model may depend on a combination of several factors, including the cell line used to induce tumor formation, the rat strains and the status of the animal's immune system.

  5. [Familial astrocytoma associated with von Recklinghausen's disease: report of two cases].

    Science.gov (United States)

    Ito, Y; Oki, S; Mikami, T; Ogasawara, H; Kawamoto, Y; Sato, H; Yamaguchi, S; Hayashi, Y; Shindo, H

    1997-03-01

    Two cases of astrocytoma associated with von Recklinghausen's disease (neurofibromatosis type; NF-1) were reported. The first case wes a 60-year-old man who had been diagnosed as von Recklinghausen's disease on the basis of skin findings. Magnetic resonance imaging (MRI) showed a tumor in the left temporal lobe. Partial removal was performed with neuronavigator, and because of the existence of Rosenthal fiber the histological diagnosis was pilocytic astrocytoma. Radiation therapy was performed. The second case was a 6-year-old boy suffering from headache and left hemiparesis including his face. MRI showed a tumor with a cyst in the right thalamus and obstructive hydrocephalus. Initially CT-guided stereotactic biopsy was performed, and the histological diagnosis, on the basis of increased cellularity, pleomorphism and nuclear atypia without necrosis or vascular proliferation, was anaplastic astrocytoma. Radiation and chemo-immuno therapy were carried out after V-P shunt. It is well known that von Recklinghausen's disease (NF-1) is often associated with optic glioma (5-36%). In the literature, the glioma seldom occurs in other parts of the brain, supratentorial glioma especially is rare. Only two familial cases of supratentorial glioma associated with von Recklinghausen's disease have been reported. The prognosis of supratentorial glioma associated with NF-1 was poor in these reports. In this paper, the diagnostic and therapeutic problems are discussed.

  6. Robust Scientists

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    their core i nterests, 2) developing a selfsupply of industry interests by becoming entrepreneurs and thus creating their own compliant industry partner and 3) balancing resources within a larger collective of researchers, thus countering changes in the influx of funding caused by shifts in political...... knowledge", Danish research policy seems to have helped develop politically and economically "robust scientists". Scientific robustness is acquired by way of three strategies: 1) tasting and discriminating between resources so as to avoid funding that erodes academic profiles and push scientists away from...

  7. Primary ciliogenesis defects are associated with human astrocytoma/glioblastoma cells

    Directory of Open Access Journals (Sweden)

    Rattner Jerome B

    2009-12-01

    Full Text Available Abstract Background Primary cilia are non-motile sensory cytoplasmic organelles that have been implicated in signal transduction, cell to cell communication, left and right pattern embryonic development, sensation of fluid flow, regulation of calcium levels, mechanosensation, growth factor signaling and cell cycle progression. Defects in the formation and/or function of these structures underlie a variety of human diseases such as Alström, Bardet-Biedl, Joubert, Meckel-Gruber and oral-facial-digital type 1 syndromes. The expression and function of primary cilia in cancer cells has now become a focus of attention but has not been studied in astrocytomas/glioblastomas. To begin to address this issue, we compared the structure and expression of primary cilia in a normal human astrocyte cell line with five human astrocytoma/glioblastoma cell lines. Methods Cultured normal human astrocytes and five human astrocytoma/glioblastoma cell lines were examined for primary cilia expression and structure using indirect immunofluorescence and electron microscopy. Monospecific antibodies were used to detect primary cilia and map the relationship between the primary cilia region and sites of endocytosis. Results We show that expression of primary cilia in normal astrocytes is cell cycle related and the primary cilium extends through the cell within a unique structure which we show to be a site of endocytosis. Importantly, we document that in each of the five astrocytoma/glioblastoma cell lines fully formed primary cilia are either expressed at a very low level, are completely absent or have aberrant forms, due to incomplete ciliogenesis. Conclusions The recent discovery of the importance of primary cilia in a variety of cell functions raises the possibility that this structure may have a role in a variety of cancers. Our finding that the formation of the primary cilium is disrupted in cells derived from astrocytoma/glioblastoma tumors provides the first

  8. Follow up of a robust meta-signature to identify Zika virus infection in Aedes aegypti: another brick in the wall

    Directory of Open Access Journals (Sweden)

    Eduardo Fukutani

    2018-05-01

    Full Text Available The mosquito Aedes aegypti is the main vector of several arthropod-borne diseases that have global impacts. In a previous meta-analysis, our group identified a vector gene set containing 110 genes strongly associated with infections of dengue, West Nile and yellow fever viruses. Of these 110 genes, four genes allowed a highly accurate classification of infected status. More recently, a new study of Ae. aegypti infected with Zika virus (ZIKV was published, providing new data to investigate whether this “infection” gene set is also altered during a ZIKV infection. Our hypothesis is that the infection-associated signature may also serve as a proxy to classify the ZIKV infection in the vector. Raw data associated with the NCBI/BioProject were downloaded and re-analysed. A total of 18 paired-end replicates corresponding to three ZIKV-infected samples and three controls were included in this study. The nMDS technique with a logistic regression was used to obtain the probabilities of belonging to a given class. Thus, to compare both gene sets, we used the area under the curve and performed a comparison using the bootstrap method. Our meta-signature was able to separate the infected mosquitoes from the controls with good predictive power to classify the Zika-infected mosquitoes.

  9. Follow up of a robust meta-signature to identify Zika virus infection in Aedes aegypti: another brick in the wall.

    Science.gov (United States)

    Fukutani, Eduardo; Rodrigues, Moreno; Kasprzykowski, José Irahe; Araujo, Cintia Figueiredo de; Paschoal, Alexandre Rossi; Ramos, Pablo Ivan Pereira; Fukutani, Kiyoshi Ferreira; Queiroz, Artur Trancoso Lopo de

    2018-01-01

    The mosquito Aedes aegypti is the main vector of several arthropod-borne diseases that have global impacts. In a previous meta-analysis, our group identified a vector gene set containing 110 genes strongly associated with infections of dengue, West Nile and yellow fever viruses. Of these 110 genes, four genes allowed a highly accurate classification of infected status. More recently, a new study of Ae. aegypti infected with Zika virus (ZIKV) was published, providing new data to investigate whether this "infection" gene set is also altered during a ZIKV infection. Our hypothesis is that the infection-associated signature may also serve as a proxy to classify the ZIKV infection in the vector. Raw data associated with the NCBI/BioProject were downloaded and re-analysed. A total of 18 paired-end replicates corresponding to three ZIKV-infected samples and three controls were included in this study. The nMDS technique with a logistic regression was used to obtain the probabilities of belonging to a given class. Thus, to compare both gene sets, we used the area under the curve and performed a comparison using the bootstrap method. Our meta-signature was able to separate the infected mosquitoes from the controls with good predictive power to classify the Zika-infected mosquitoes.

  10. The emerging role of m-TOR up-regulation in brain Astrocytoma.

    Science.gov (United States)

    Ryskalin, Larisa; Limanaqi, Fiona; Biagioni, Francesca; Frati, Alessandro; Esposito, Vincenzo; Calierno, Maria Teresa; Lenzi, Paola; Fornai, Francesco

    2017-05-01

    The present manuscript is an overview of various effects of mTOR up-regulation in astrocytoma with an emphasis on its deleterious effects on the proliferation of Glioblastoma Multiforme. The manuscript reports consistent evidence indicating the occurrence of mTOR up-regulation both in experimental and human astrocytoma. The grading of human astrocytoma is discussed in relationship with mTOR up-regulation. In the second part of the manuscript, the biochemical pathways under the influence of mTOR are translated to cell phenotypes which are generated by mTOR up-regulation and reverted by its inhibition. A special section is dedicated to the prominent role of autophagy in mediating the effects of mTOR in glioblastoma. In detail, autophagy inhibition produced by mTOR up-regulation determines the fate of cancer stem cells. On the other hand, biochemical findings disclose the remarkable effects of autophagy activators as powerful inducers of cell differentiation with a strong prevalence towards neuronal phenotypes. Thus, mTOR modulation acts on the neurobiology of glioblastoma just like it operates in vivo at the level of brain stem cell niches by altering autophagy-dependent cell differentiation. In the light of such a critical role of autophagy we analyzed the ubiquitin proteasome system. The merging between autophagy and proteasome generates a novel organelle, named autophagoproteasome which is strongly induced by mTOR inhibitors in glioblastoma cells. Remarkably, when mTOR is maximally inhibited the proteasome component selectively moves within autophagy vacuoles, thus making the proteasome activity dependent on the entry within autophagy compartment.

  11. [The heterogeneity of blood flow on magnetic resonance imaging: a biomarker for grading cerebral astrocytomas].

    Science.gov (United States)

    Revert Ventura, A J; Sanz Requena, R; Martí-Bonmatí, L; Pallardó, Y; Jornet, J; Gaspar, C

    2014-01-01

    To study whether the histograms of quantitative parameters of perfusion in MRI obtained from tumor volume and peritumor volume make it possible to grade astrocytomas in vivo. We included 61 patients with histological diagnoses of grade II, III, or IV astrocytomas who underwent T2*-weighted perfusion MRI after intravenous contrast agent injection. We manually selected the tumor volume and peritumor volume and quantified the following perfusion parameters on a voxel-by-voxel basis: blood volume (BV), blood flow (BF), mean transit time (TTM), transfer constant (K(trans)), washout coefficient, interstitial volume, and vascular volume. For each volume, we obtained the corresponding histogram with its mean, standard deviation, and kurtosis (using the standard deviation and kurtosis as measures of heterogeneity) and we compared the differences in each parameter between different grades of tumor. We also calculated the mean and standard deviation of the highest 10% of values. Finally, we performed a multiparametric discriminant analysis to improve the classification. For tumor volume, we found statistically significant differences among the three grades of tumor for the means and standard deviations of BV, BF, and K(trans), both for the entire distribution and for the highest 10% of values. For the peritumor volume, we found no significant differences for any parameters. The discriminant analysis improved the classification slightly. The quantification of the volume parameters of the entire region of the tumor with BV, BF, and K(trans) is useful for grading astrocytomas. The heterogeneity represented by the standard deviation of BF is the most reliable diagnostic parameter for distinguishing between low grade and high grade lesions. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

  12. Overexpression of c-erbB2 is a negative prognostic factor in anaplastic astrocytomas

    Directory of Open Access Journals (Sweden)

    Gulati Michel

    2010-03-01

    Full Text Available Abstract The epidermal growth factor receptor (EGFR family, consisting of four tyrosine kinase receptors, c-erbB1-4, seems to be influential in gliomagenesis. The aim of this study was to investigate EGFR gene amplification and expression of c-erbB1-4 receptor proteins in human anaplastic astrocytomas. Formalin-fixed and paraffin-embedded sections from 31 cases were investigated by standard immunohistochemical procedures for expression of c-erbB1-4 receptor proteins using commercial antibodies. EGFR gene amplification was studied by fluorescence in situ hybridization using paraffin-embedded tissues. Two monoclonal antibodies, NCL-EGFR-384 and NCL-EGFR, were used for EGFR detection and they displayed positive immunoreactivity in 97% and 71%, respectively. For c-erbB2 detection three monoclonal antibodies, CB11, 3B5, and 5A2, were applied and they displayed positive immunoreactivity in 45%, 100%, and 52%, respectively. Positive immunostaining for c-erbB3 and c-erbB4 was encountered in 97% and 74%, respectively. The EGFR gene was amplified in 9 out of 31 tumors (29%. After adjusting for age, Karnofsky performance status, and extent of surgical resection, Cox multiple regression analysis with overall survival as the dependent variable revealed that c-erbB2 overexpression detected by the monoclonal antibody clone CB11 was a statistically significant poor prognostic factor (P = 0.004. This study shows the convenience and feasibility of immunohistochemistry when determining the expression of receptor proteins in tissue sections of human astrocytomas. The synchronous overexpression of c-erbB1-4 proteins in anaplastic astrocytomas supports their role in the pathogenesis of these tumors. Further, c-erbB2 overexpression seems to predict aggressive behaviour.

  13. Outcome and patterns of failure following limited-volume irradiation for malignant astrocytomas

    Energy Technology Data Exchange (ETDEWEB)

    Garden, A.S.; Maor, M.H.; Yung, W.K.A.; Bruner, J.M.; Woo, Shiao Y.; Moser, R.P.; Lee, Ya-Yen (Anderson (M.D.) Hospital and Tumor Inst., Houston, TX (USA))

    1991-02-01

    Between January 1982 and June 1986, 60 consecutive patients with high-grade astrocytomas (39 glioblastoma multiforme (GBM), 21 anaplastic astrocytoma (AA)) were treated with radiation therapy after biopsy (13 patients) or resection (47 patients). 53 patients were treated with limited-volume irradiation, 7 received whole-brain irradiation. The mean tumor dose was 65.4 Gy. In 35 patients, chemotherapy was given as part of their initial treatment. The 1- and 2-year survivals for GBM patients were 40 and 14 percent, respectively. Survival figures for AA patients were 76 and 52 percent at 1 and 2 years, respectively. The progression-free rate at 1 year was 13 percent in GBM and 29 percent in AA patients. 34 of 48 patients who received limited-volume irradiation had evidence of progression on postirradiation CT scans. 6 patients (3 GBM, 3 AA) had evidence of a new intracranial metastatic site on CT scan. In 3 patients the metastasis was within the previously irradiated volume, and in 3 other patients, it was outside this volume. All 6 had evidence of progression of their primary tumor at the original location on CT scan prior to the discovery of the metastatic site. 21 patients (15 GBM, 6 AA) had at least 1 postirradiation reoperation for a recurrent mass. 19 patients had recurrent tumors in the primary site, and 2 patients had necrosis but no tumor. Patients who received limited-volume irradiation for high-grade astrocytomas achieved the same survival results as patients treated previously with whole brain irradiation. New intra-cranial metastases did not influence the outcome, since these were always antedated by tumor progression at the primary site. (author). 16 refs.; 8 figs.; 2 tabs.

  14. An infant with hyperalertness, hyperkinesis, and failure to thrive: a rare diencephalic syndrome due to hypothalamic anaplastic astrocytoma.

    Science.gov (United States)

    Stival, Alessia; Lucchesi, Maurizio; Farina, Silvia; Buccoliero, Anna Maria; Castiglione, Francesca; Genitori, Lorenzo; de Martino, Maurizio; Sardi, Iacopo

    2015-09-04

    Diencephalic Syndrome is a rare clinical condition of failure to thrive despite a normal caloric intake, hyperalertness, hyperkinesis, and euphoria usually associated with low-grade hypothalamic astrocytomas. We reported an unusual case of diencephalic cachexia due to hypothalamic anaplastic astrocytoma (WHO-grade III). Baseline endocrine function evaluation was performed in this patient before surgery. After histological diagnosis, he enrolled to a chemotherapy program with sequential high-dose chemotherapy followed by hematopoietic stem cell rescue. The last MRI evaluation showed a good response. The patient is still alive with good visual function 21 months after starting chemotherapy. Diencephalic cachexia can rarely be due to high-grade hypothalamic astrocytoma. We suggest that a nutritional support with chemotherapy given to high doses without radiotherapy could be an effective strategy for treatment of a poor-prognosis disease.

  15. Differential prefrontal-like deficit in children after cerebellar astrocytoma and medulloblastoma tumor

    Directory of Open Access Journals (Sweden)

    Quintero Eliana A

    2008-04-01

    Full Text Available Abstract Background This study was realized thanks to the collaboration of children and adolescents who had been resected from cerebellar tumors. The medulloblastoma group (CE+, n = 7 in addition to surgery received radiation and chemotherapy. The astrocytoma group (CE, n = 13 did not receive additional treatments. Each clinical group was compared in their executive functioning with a paired control group (n = 12. The performances of the clinical groups with respect to controls were compared considering the tumor's localization (vermis or hemisphere and the affectation (or not of the dentate nucleus. Executive variables were correlated with the age at surgery, the time between surgery-evaluation and the resected volume. Methods The executive functioning was assessed by means of WCST, Complex Rey Figure, Controlled Oral Word Association Test (letter and animal categories, Digits span (WISC-R verbal scale and Stroop test. These tests are very sensitive to dorsolateral PFC and/or to medial frontal cortex functions. The scores for the non-verbal Raven IQ were also obtained. Direct scores were corrected by age and transformed in standard scores using normative data. The neuropsychological evaluation was made at 3.25 (SD = 2.74 years from surgery in CE group and at 6.47 (SD = 2.77 in CE+ group. Results The Medulloblastoma group showed severe executive deficit (≤ 1.5 SD below normal mean in all assessed tests, the most severe occurring in vermal patients. The Astrocytoma group also showed executive deficits in digits span, semantic fluency (animal category and moderate to slight deficit in Stroop (word and colour tests. In the astrocytoma group, the tumor's localization and dentate affectation showed different profile and level of impairment: moderate to slight for vermal and hemispheric patients respectively. The resected volume, age at surgery and the time between surgery-evaluation correlated with some neuropsychological executive variables

  16. FGFR1 tyrosine kinase domain duplication in pilocytic astrocytoma with anaplasia.

    Science.gov (United States)

    Ballester, Leomar Y; Penas-Prado, Marta; Leeds, Norman E; Huse, Jason T; Fuller, Gregory N

    2018-04-01

    We report the case of a 27-yr-old male with visual field loss who had a 4.9-cm complex cystic mass in the right occipital lobe. Histologic examination showed pilocytic astrocytoma (PA) with anaplasia, and molecular characterization revealed FGFR1 duplication with additional variants of unknown significance in several genes ( ARID1A, ARID1B, CHEK2, EPHA5, and MLL2 ). This is one of only a very few reported cases of anaplastic PA with characterization of molecular alterations. © 2018 Ballester et al.; Published by Cold Spring Harbor Laboratory Press.

  17. Classification of astrocyto-mas and meningiomas using statistical discriminant analysis on MRI data

    International Nuclear Information System (INIS)

    Siromoney, Anna; Prasad, G.N.S.; Raghuram, Lakshminarayan; Korah, Ipeson; Siromoney, Arul; Chandrasekaran, R.

    2001-01-01

    The objective of this study was to investigate the usefulness of Multivariate Discriminant Analysis for classifying two groups of primary brain tumours, astrocytomas and meningiomas, from Magnetic Resonance Images. Discriminant analysis is a multivariate technique concerned with separating distinct sets of objects and with allocating new objects to previously defined groups. Allocation or classification rules are usually developed from learning examples in a supervised learning environment. Data from signal intensity measurements in the multiple scan performed on each patient in routine clinical scanning was analysed using Fisher's Classification, which is one method of discriminant analysis

  18. An acid phosphatase in the plasma membranes of human astrocytoma showing marked specificity toward phosphotyrosine protein.

    Science.gov (United States)

    Leis, J F; Kaplan, N O

    1982-11-01

    The plasma membrane from the human tumor astrocytoma contains an active acid phosphatase activity based on hydrolysis of p-nitrophenyl phosphate. Other acid phosphatase substrates--beta-glycerophosphate, O-phosphorylcholine, and 5'-AMP--are not hydrolyzed significantly. The phosphatase activity is tartrate insensitive and is stimulated by Triton X-100 and EDTA. Of the three known phosphoamino acids, only free O-phosphotyrosine is hydrolyzed by the membrane phosphatase activity. Other acid phosphatases tested from potato, wheat germ, milk, and bovine prostate did not show this degree of specificity. The plasma membrane activity also dephosphorylated phosphotyrosine histone at a much greater rate than did the other acid phosphatases. pH profiles for free O-phosphotyrosine and phosphotyrosine histone showed a shift toward physiological pH, indicating possible physiological significance. Phosphotyrosine histone dephosphorylation activity was nearly 10 times greater than that seen for phosphoserine histone dephosphorylation, and Km values were much lower for phosphotyrosine histone dephosphorylation (0.5 microM vs. 10 microM). Fluoride and zinc significantly inhibited phosphoserine histone dephosphorylation. Vanadate, on the other hand, was a potent inhibitor of phosphotyrosine histone dephosphorylation (50% inhibition at 0.5 microM) but not of phosphoserine histone. ATP stimulated phosphotyrosine histone dephosphorylation (160-250%) but inhibited phosphoserine histone dephosphorylation (95%). These results suggest the existence of a highly specific phosphotyrosine protein phosphatase activity associated with the plasma membrane of human astrocytoma.

  19. Quality of life and neuropsychological evaluation for patients with malignant astrocytomas: RTOG 91-14

    International Nuclear Information System (INIS)

    Choucair, Ali K.; Scott, Charles; Urtasun, Raul; Nelson, Diana; Mousas, Benjamin; Curran, Walter

    1997-01-01

    Abstract: With increasingly aggressive neurosurgical and radiation therapy modalities (gamma knife, external beam stereotactic radiation and interstitial brachytherapy with or without hyperthermia) offered to patients with malignant astrocytomas (MA), increasing national demand for medical outcome studies and rising health care costs amidst public, business, and governmental debate to cut spending, we as physicians are obligated to continue our research to find effective treatments for malignant astrocytoma (MA) and a cost-effective means to study their impact upon the patient's quality of life (QOL). Purpose: We report data that was collected within the Radiation Therapy Oncology Group (RTOG) on 126 patients with MA who were enrolled in RTOG 91-14. This study was undertaken to prospectively test the feasibility of performing quality of life (QOL) and neuropsychological evaluation (NPE) and collecting this data within the RTOG. Results: The NPE and QOL parameters that were used in this study are cost effective. They are not only much cheaper than formal cognitive and memory testing, but also provide additional information regarding the patients' day to day functional abilities that are not provided by the current routinely used means, such as KPS. The Mini-Mental Status Exam (MMSE) provides greater sensitivity to patients' differences in neurological status and may be preferable to NFS as an eligibility criteria

  20. Cloning of a novel transcription factor-like gene amplified in human glioma including astrocytoma grade I

    NARCIS (Netherlands)

    Fischer, U.; Heckel, D.; Michel, A.; Janka, M.; Hulsebos, T.; Meese, E.

    1997-01-01

    Gene amplification, which is generally considered to occur late in tumor development, is a common feature of high grade glioma. Up until now, there have been no reports on amplification in astrocytoma grade I. In this study, we report cloning and sequencing of a cDNA termed glioma-amplified sequence

  1. Lack of prognostic significance of C-erbB-2 expression in low- and high- grade astrocytomas.

    Science.gov (United States)

    Muallaoglu, Saik; Besen, Ali Ayberk; Ata, Alper; Mertsoylu, Huseyin; Arican, Ali; Kayaselcuk, Fazilet; Ozyilkan, Ozgur

    2014-01-01

    Astrocytic tumors, the most common primary glial tumors of the central nervous system, are classified from low to high grade according to the degree of anaplasia and presence of necrosis. Despite advances in therapeutic management of high grade astrocytic tumors, prognosis remains poor. In the present study, the frequency and prognostic significance of c-erb-B2 in astrocytic tumors was investigated. Records of 72 patients with low- and high-grade astrocytic tumors were evaluated. The expression of C-erbB-2 was determined immunohistochemically and intensity was recorded as 0 to 3+. Tumors with weak staining (1+) or no staining (0) were considered Her-2 negative, while tumors with moderate (2+) and strong (3+) staining were considered Her-2 positive. Of the 72 patients, 41 (56.9%) had glioblastoma (GBM), 10 (13.9%) had diffuse astrocytoma, 15 (20.8%) had anaplastic astrocytoma, 6 (8.3%) had pilocytic astrocytoma. C-erbB-2 overexpression was detected in the tumor specimens of 17 patients (23.6%). Six (8.3%) tumors, all GBMs, exhibited strong staining, 2 (2.7%) specimens, both GBMs, exhibited moderate staining, and 9 specimens, 5 of them GBMs (12.5%), exhibited weak staining. No staining was observed in diffuse astrocytoma and pilocytic astrocytoma specimens. Median overall survival of patients with C-erbB-2 negative and C-erbB-2 positive tumors were 30 months (95%CI: 22.5-37.4 months) and 16.9 months (95%CI: 4.3-29.5 months), respectively (p=0.244). Although there was no difference in survival, C-erbB-2 overexpression was observed only in the GBM subtype.

  2. External Beam Radiotherapy in the Management of Low Grade Astrocytoma of the Brain

    International Nuclear Information System (INIS)

    Jeon, Ha Jung

    2009-01-01

    This study was designed to evaluate the effectiveness of postoperative radiotherapy for patients with low-grade astrocytomas and to define an optimal radiotherapeutic regimen and prognostic factors. A total of 69 patients with low-grade astrocytomas underwent surgery and postoperative radiotherapy immediately following surgery at our institution between October 1989 and September 2006. The median patient age was 36 years. Forty-one patients were 40 years or younger and 28 patients were 41 years or older. Fourteen patients underwent a biopsy alone and the remaining 55 patients underwent a subtotal resection. Thirty-nine patients had a Karnofsky performance status of less than 80% and 30 patients had a Karnofsky performance status greater than 80%. Two patients were treated with whole brain irradiation followed by a coned down boost field to the localized area. The remaining 67 patients were treated with a localized field with an appropriate margin. Most of the patients received a dose of 50∼55 Gy and majority of the patients were treated with a dose of 54 Gy. The overall 5-year and 7-year survival rates for all of the 69 patients were 49% and 44%, respectively. Corresponding disease free survival rates were 45% and 40%, respectively. Patients who underwent a subtotal resection showed better survival than patients who underwent a biopsy alone. The overall 5-year survival rates for patients who underwent a subtotal resection and patients who underwent a biopsy alone were 57% and 38%, respectively (p<0.05). Forty-one patients who were 40 years or younger showed a better overall 5-year survival rate as compared with 28 patients who were 41 years or older (56% versus 40%, p<0.05). The overall 5-year survival rates for 30 patients with a Karnofsky performance status greater than 80% and 39 patients with a Karnofsky performance status less than 80% were 51% and 47%, respectively. This finding was not statistically significant. Although one patient was not able to

  3. Pediatric spinal cord astrocytomas: a retrospective study of 348 patients from the SEER database.

    Science.gov (United States)

    Luksik, Andrew S; Garzon-Muvdi, Tomas; Yang, Wuyang; Huang, Judy; Jallo, George I

    2017-06-01

    OBJECTIVE Intramedullary spinal cord tumors comprise 1%-10% of all childhood central nervous system neoplasms, with astrocytomas representing the most common subtype. Due to their rarity and poor prognosis, large population-based studies are needed to assess the epidemiology and survival risk factors associated with these tumors in the hope of improving outcome. The authors undertook this retrospective study to explore factors that may influence survival in pediatric patients with spinal cord astrocytomas. METHODS Utilizing the Surveillance, Epidemiology, and End Results (SEER) database, a prospective cancer registry, the authors retrospectively assessed survival in histologically confirmed, primary spinal cord astrocytomas in patients 21 years of age and younger. Survival was described with Kaplan-Meyer curves, and a multivariate regression analysis was used to assess the association of several variables with survival while controlling for confounding variables. RESULTS This analysis of 348 cases showed that age (hazard ratio [HR] 1.05, 95% CI 1.01-1.09, p = 0.017), nonwhite race (HR 1.74, 95% CI 1.11-2.74, p = 0.014), high-grade tumor status (HR 14.67, 95% CI 6.69-32.14, p < 0.001), distant or invasive extension of the tumor (HR 2.37, 95% CI 1.02-5.49, p = 0.046), and radiation therapy (HR 3.74, 95% CI 2.18-6.41, p < 0.001) were associated with decreased survival. Partial resection (HR 0.37, 95% CI 0.16-0.83, p = 0.017) and gross-total resection (HR 0.39, 95% CI 0.16-0.95, p = 0.039) were associated with improved survival. CONCLUSIONS Younger age appears to be protective, while high-grade tumors have a much worse prognosis. Early diagnosis and access to surgery appears necessary for improving outcomes, while radiation therapy has an unclear role. There is still much to learn about this disease in the hope of curing children with the misfortune of having one of these rare tumors.

  4. Approach to the irradiation of extensive cervical and upper thoracic spinal astrocytoma

    International Nuclear Information System (INIS)

    Dvorak, E.

    1981-01-01

    Intramedullary spinal cord tumors are relatively rare, especially to the extent presented in this report. A 31-year-old woman had been diagnosed as having an inoperable astrocytoma, grade I-II, involving the entire cervical spinal cord and two upper thoracic segments. After decompressive laminectomy, she was referred for a radical course of radiation therapy. An irradiation technique was devised which allowed treatment of a single cylindrical volume of tissue encompassing the known tumor. Field fractionation with undesirable gaps and/or excessive dose to overlying normal structures was avoided. To the cervical spinal cord she received 5590 cGy in 29 fractions over 42 days. By this schedule she received at the same time 4820 cGy to the medulla oblongata and 4880 cGy to the upper thoracic cord. Partial neurological improvement occurred at the end of the treatment. The treatment approach is discussed in the background of the literature data. (orig.) [de

  5. Effect of chemoradiotherapy using ACNU, vincristine, and nicardipine with high-dose irradiation on malignant astrocytomas

    Energy Technology Data Exchange (ETDEWEB)

    Genka, Shigeru; Shitara, Nobuyuki; Nakamura, Hirohiko; Takakura, Kintomo [Tokyo Univ. (Japan). Hospital

    1993-05-01

    Fifty-two patients with malignant astrocytoma were treated with cellular synchronization radiation therapy at the University of Tokyo Hospital between 1977 and 1989. Twenty-five patients (Group 1) received 1 - (4-amino-2-methyl-5-pyrimidinyl)methyl - 3 - (2-chloroethyl) - 3 - nitrosourea hydrochloride (ACNU), vincristine, and 60 Gy of irradiation, and 27 patients (Group 2) ACNU, vincristine, the Ca-channel blocker nicardipine, and 72 Gy of irradiation. Median survival times for Groups 1 and 2 were 15 and 30 months, respectively. Although there was no significant difference, Group 2 achieved longer survival with 1-, 2-, and 3-year survival rates of 85.2, 65.8, and 46.9% compared to rates of 66.7, 40.0, and 26.7%, respectively, for Group 1. (author).

  6. A case of paraventricular anaplastic astrocytoma following radiation therapy for craniopharyngioma

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Hiroaki; Fujiwara, Kazunori; Kobayashi, Shin-ichi; Kitahara, Masakazu (Ishinomaki Red Cross Hospital, Miyagi (Japan))

    1994-04-01

    A 20-year-old man received 60 Gy of radiation therapy after partial removal of craniopharyngioma. The patient had been well and follow-up CT scans did not show any aggravation for 16 years. Since his activity gradually diminished, he underwent an MRI at the age of 36 which revealed and abnormal mass on the corpus callosum. The mass lesion progressively enlarged thereafter, and was diagnosed as anaplastic astrocytoma by a stereotactic biopsy. He was treated with interferon, however, died at the age of 37. Review of the literature disclosed 19 other cases of glioma following radiation therapy for sellar/parasellar tumors. Characteristic features of these cases included (1) lowness of age compared to common glioma cases, (2) tendency to be malignant, (3) tendency to occur in areas where significant doses of radiation had been received previously. (author).

  7. Imaging findings of anaplastic astrocytoma in a child with maple syrup urine disease: a case report.

    Science.gov (United States)

    Aw-Zoretic, Jessie; Wadhwani, Nitin R; Lulla, Rishi R; Rishi, Lulla R; Ryan, Maura E

    2015-09-01

    Maple syrup urine disease (MSUD) is an inborn error of branched-chain amino acid metabolism, which usually presents in childhood with encephalopathy due to cerebral edema and dysmyelination. Even with treatment, metabolic stressors may precipitate later episodes of acute decompensation. Changes related to cerebral and white matter edema have been described by magnetic resonance imaging (MRI), and imaging can aid in both initial diagnosis and evaluation of decompensation. To date, there are no published known reports of cancer in patients with MSUD. Here, we present the first case report of an anaplastic astrocytoma in a teenager with MSUD, with a discussion of imaging findings and the use of magnetic resonance spectroscopy (MRS) to help distinguish between tumor and metabolic changes.

  8. Effect of chemoradiotherapy using ACNU, vincristine, and nicardipine with high-dose irradiation on malignant astrocytomas

    International Nuclear Information System (INIS)

    Genka, Shigeru; Shitara, Nobuyuki; Nakamura, Hirohiko; Takakura, Kintomo

    1993-01-01

    Fifty-two patients with malignant astrocytoma were treated with cellular synchronization radiation therapy at the University of Tokyo Hospital between 1977 and 1989. Twenty-five patients (Group 1) received 1 - (4-amino-2-methyl-5-pyrimidinyl)methyl - 3 - (2-chloroethyl) - 3 - nitrosourea hydrochloride (ACNU), vincristine, and 60 Gy of irradiation, and 27 patients (Group 2) ACNU, vincristine, the Ca-channel blocker nicardipine, and 72 Gy of irradiation. Median survival times for Groups 1 and 2 were 15 and 30 months, respectively. Although there was no significant difference, Group 2 achieved longer survival with 1-, 2-, and 3-year survival rates of 85.2, 65.8, and 46.9% compared to rates of 66.7, 40.0, and 26.7%, respectively, for Group 1. (author)

  9. High accuracy of arterial spin labeling perfusion imaging in differentiation of pilomyxoid from pilocytic astrocytoma

    Energy Technology Data Exchange (ETDEWEB)

    Nabavizadeh, S.A.; Assadsangabi, R.; Hajmomenian, M.; Vossough, A. [Perelman School of Medicine of the University of Pennsylvania, Department of Radiology, Children' s Hospital of Philadelphia, Philadelphia, PA (United States); Santi, M. [Perelman School of Medicine of the University of Pennsylvania, Department of Pathology, Children' s Hospital of Philadelphia, Philadelphia, PA (United States)

    2015-05-01

    Pilomyxoid astrocytoma (PMA) is a relatively new tumor entity which has been added to the 2007 WHO Classification of tumors of the central nervous system. The goal of this study is to utilize arterial spin labeling (ASL) perfusion imaging to differentiate PMA from pilocytic astrocytoma (PA). Pulsed ASL and conventional MRI sequences of patients with PMA and PA in the past 5 years were retrospectively evaluated. Patients with history of radiation or treatment with anti-angiogenic drugs were excluded. A total of 24 patients (9 PMA, 15 PA) were included. There were statistically significant differences between PMA and PA in mean tumor/gray matter (GM) cerebral blood flow (CBF) ratios (1.3 vs 0.4, p < 0.001) and maximum tumor/GM CBF ratio (2.3 vs 1, p < 0.001). Area under the receiver operating characteristic (ROC) curves for differentiation of PMA from PA was 0.91 using mean tumor CBF, 0.95 using mean tumor/GM CBF ratios, and 0.89 using maximum tumor/GM CBF. Using a threshold value of 0.91, the mean tumor/GM CBF ratio was able to diagnose PMA with 77 % sensitivity, 100 % specificity, and a threshold value of 0.7, provided 88 % sensitivity and 86 % specificity. There was no statistically significant difference between the two tumors in enhancement pattern (p = 0.33), internal architecture (p = 0.15), or apparent diffusion coefficient (ADC) values (p = 0.07). ASL imaging has high accuracy in differentiating PMA from PA. The result of this study may have important applications in prognostication and treatment planning especially in patients with less accessible tumors such as hypothalamic-chiasmatic gliomas. (orig.)

  10. Pion radiation for high grade astrocytoma: results of a randomized study

    International Nuclear Information System (INIS)

    Pickles, Tom; Goodman, George B.; Rheaume, Dorianne E.; Duncan, Graeme G.; Fryer, Chris J.; Bhimji, Shamim; Ludgate, Charles; Syndikus, Isabel; Graham, Peter; Dimitrov, Mario; Bowen, Julie

    1997-01-01

    Purpose: This study attempted to compare within a randomized study the outcome of pion radiation therapy vs. conventional photon irradiation for the treatment of high-grade astrocytomas. Methods and Materials: Eighty-four patients were randomized to pion therapy (33-34.5 Gyπ), or conventional photon irradiation (60 Gy). Entry criteria included astrocytoma (modified Kernohan high Grade 3 or Grade 4), age 18-70, Karnofsky performance status (KPS) ≥50, ability to start irradiation within 30 days of surgery, unifocal tumor, and treatment volume < 850 cc. The high-dose volume in both arms was computed tomography enhancement plus a 2-cm margin. The study was designed with the power to detect a twofold difference between arms. Results: Eighty-one eligible patients were equally balanced for all known prognostic variables. Pion patients started radiation 7 days earlier on average than photon patients, but other treatment-related variables did not differ. There were no significant differences for either early or late radiation toxicity between treatment arms. Actuarial survival analysis shows no differences in terms of time to local recurrence or overall survival where median survival was 10 months in both arms (p = 0.22). The physician-assessed KPS and patient-assessed quality of life (QOL) measurements were generally maintained within 10 percentage points until shortly before tumor recurrence. There was no apparent difference in the serial KPS or QOL scores between treatment arms. Conclusion: In contrast to high linear energy transfer (LET) therapy for central nervous system tumors, such as neutron or neon therapy, the safety of pion therapy, which is of intermediate LET, has been reaffirmed. However, this study has demonstrated no therapeutic gain for pion therapy of glioblastoma

  11. The role of radiotherapy in the management of supratentorial low grade astrocytoma

    International Nuclear Information System (INIS)

    Song, M. H.; Chang, H. S.; Lee, K. J.

    1997-01-01

    To evaluate the role of radiotherapy in the management of incompletely resected supratentorial low grade astrocytoma with the analysis of the survival, the pattern of failure, and the prognostic variables affecting survival. Between January 1990 and December 1995, fifty-one patients with supratentorial low grade astrocytoma received radiotherapy after subtotal resection (16 patients) or stereotactic biopsy(35 patients)at Asan Medical Center. External radiotherapy was done by conventional fractionation with the total dose of 4820cGy to 6000cGy(median 5580cGy) and partial brain volume. The follow-up was done from 6 to 79 months(median 48 months). Overall actuarial survival rate at 2 and 5 years were 83.4% and 54.8T, respectively. Progression free survival at 2 and 5 years were 67.4% and 48.7%, respectively. The significant prognostic factors affecting overall survival rate were the performance status, T stage, histologic subtype, radiation field and radiation response. The major pattern of failure was local failure, such as progressive disease and primary site recurrence in 23 patients (45.1%). Progression free survivors excluding 2 patients were physically and intellectually intact without major neurologic deficit. Although the follow-up period of this study was relatively short, overall actuarial and progression free survival rate were encouraging. Patients with good performance status, lower T stage, pilocytic subtype, patients treated with small radiation field and radiation responder showed better survival. As the local failure was the major pattern of failure, the various efforts to decrease the local failure is necessary. (author)

  12. Phase II trial of carmustine, cisplatin, and oral etoposide chemotherapy before radiotherapy for grade 3 astrocytoma (anaplastic astrocytoma): Results of North Central Cancer Treatment Group trial 98-72-51

    International Nuclear Information System (INIS)

    Rao, Ravi D.; Krishnan, Sunil; Fitch, Tom R.; Schomberg, Paula J.; Dinapoli, Robert P.; Nordstrom, Kathleen; Scheithauer, Bernd; O'Fallon, Judith R.; Maurer, Matthew J. M.S.; Buckner, Jan C.

    2005-01-01

    Purpose: To evaluate the efficacy of preradiotherapy (RT) chemotherapy with carmustine, cisplatin, and oral etoposide combined with RT in the treatment of newly diagnosed anaplastic astrocytoma. Methods and materials: Therapy consisted of carmustine (40 mg/m 2 /d) on Days 1-3, oral etoposide (50 mg/d) on Days 1-21 and 29-49, and cisplatin (20 mg/m 2 /d i.v.) on Days 1-3 and 29-31. The regimen was repeated every 8 weeks for three cycles, with conventionally fractionated RT (5000 cGy with a 1000-cGy boost) delivered concurrently with the third cycle. Results: A total of 29 patients were enrolled between December 1999 and March 2001. For varying reasons (e.g., progression, refusal, death, or toxicity), only 48% completed the chemotherapy regimen and 76% completed RT. Grade 3-4 toxicities were observed in 14 patients (48%). The primary study endpoint was the 23-month (700-day) survival, the median survival of patients with anaplastic astrocytoma in a previous North Central Cancer Treatment Group trial. To be considered an active treatment, a maximum of 9 patient deaths (of the first 25) were allowed before 700 days. However, 14 patients had died by 700 days after therapy. Conclusion: Our results have demonstrated that pre-RT chemotherapy with this regimen is insufficiently active in patients with anaplastic astrocytoma

  13. Methylation profiles of thirty four promoter-CpG islands and concordant methylation behaviours of sixteen genes that may contribute to carcinogenesis of astrocytoma

    Directory of Open Access Journals (Sweden)

    Wang Yifei

    2004-09-01

    Full Text Available Abstract Background Astrocytoma is a common aggressive intracranial tumor and presents a formidable challenge in the clinic. Association of altered DNA methylation patterns of the promoter CpG islands with the expression profile of cancer-related genes, has been found in many human tumors. Therefore, DNA methylation status as such may serve as an epigenetic biomarker for both diagnosis and prognosis of human tumors, including astrocytoma. Methods We used the methylation specific PCR in conjunction with sequencing verification to establish the methylation profile of the promoter CpG island of thirty four genes in astrocytoma tissues from fifty three patients (The WHO grading:. I: 14, II: 15, III: 12 and IV: 12 cases, respectively. In addition, compatible tissues (normal tissues distant from lesion from three non-astrocytoma patients were included as the control. Results Seventeen genes (ABL, APC, APAF1, BRCA1, CSPG2, DAPK1, hMLH1, LKB1, PTEN, p14ARF, p15INK4b, p27KIP1, p57KIP2, RASSF1C, RB1, SURVIVIN, and VHL displayed a uniformly unmethylated pattern in all the astrocytoma and non-astrocytoma tissues examined. However, the MAGEA1 gene that was inactivated and hypermethylated in non-astrocytoma tissues, was partially demethylated in 24.5% of the astrocytoma tissues (co-existence of the hypermethylated and demethylated alleles. Of the astrocytoma associated hypermethylated genes, the methylation pattern of the CDH13, cyclin a1, DBCCR1, EPO, MYOD1, and p16INK4a genes changed in no more than 5.66% (3/53 of astrocytoma tissues compared to non-astrocytoma controls, while the RASSF1A, p73, AR, MGMT, CDH1, OCT6,, MT1A, WT1, and IRF7 genes were more frequently hypermethylated in 69.8%, 47.2%, 41.5%, 35.8%, 32%, 30.2%, 30.2%, 30.2% and 26.4% of astrocytoma tissues, respectively. Demethylation mediated inducible expression of the CDH13, MAGEA1, MGMT, p73 and RASSF1A genes was established in an astrocytoma cell line (U251, demonstrating that expression of

  14. The Crane Robust Control

    Directory of Open Access Journals (Sweden)

    Marek Hicar

    2004-01-01

    Full Text Available The article is about a control design for complete structure of the crane: crab, bridge and crane uplift.The most important unknown parameters for simulations are burden weight and length of hanging rope. We will use robustcontrol for crab and bridge control to ensure adaptivity for burden weight and rope length. Robust control will be designed for current control of the crab and bridge, necessary is to know the range of unknown parameters. Whole robust will be splitto subintervals and after correct identification of unknown parameters the most suitable robust controllers will be chosen.The most important condition at the crab and bridge motion is avoiding from burden swinging in the final position. Crab and bridge drive is designed by asynchronous motor fed from frequency converter. We will use crane uplift with burden weightobserver in combination for uplift, crab and bridge drive with cooperation of their parameters: burden weight, rope length and crab and bridge position. Controllers are designed by state control method. We will use preferably a disturbance observerwhich will identify burden weight as a disturbance. The system will be working in both modes at empty hook as well asat maximum load: burden uplifting and dropping down.

  15. Preliminary individualized chemotherapy for malignant astrocytomas based on O6-methylguanine-deoxyribonucleic acid methyltransferase methylation analysis.

    Science.gov (United States)

    Watanabe, Takao; Katayama, Yoichi; Ogino, Akiyoshi; Ohta, Takashi; Yoshino, Atsuo; Fukushima, Takao

    2006-08-01

    O(6)-methylguanine-deoxyribonucleic acid methyltransferase gene (MGMT) methylation is apparently correlated with responsiveness to nitrosourea chemotherapy, suggesting this alkylating agent should be effective against MGMT-methylated tumors. MGMT appears not to be linked to platinum resistance, so platinum chemotherapy should be used for MGMT-unmethylated tumors. This study was a preliminary trial of individualized chemotherapy based on MGMT methylation status in a total of 20 patients with newly diagnosed malignant astrocytomas (9 anaplastic astrocytomas and 11 glioblastomas multiforme). The procarbazine, 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-2(2-chloroethyl)-3-nitrosourea, and vincristine (PAV) regimen was administered to seven patients with MGMT-methylated tumors, and the carboplatin and etoposide (CE) regimen was administered to 13 patients with MGMT-unmethylated tumors. Objective response to the PAV therapy was noted in all three patients with measurable residual tumor (2 complete responses and 1 partial response). Five of the seven patients continued to be disease-free after initiation of the PAV therapy. Objective response to the CE therapy was seen in only one of seven patients with measurable residual tumor (1 partial response). Three of the 13 patients were free from progression, whereas the remaining 10 patients showed early progression. The PAV regimen is effective against MGMT-methylated malignant astrocytomas, but the CE regimen is not useful at the given dose and schedule in MGMT-unmethylated tumors.

  16. Malignant Trigeminal Nerve Sheath Tumor and Anaplastic Astrocytoma Collision Tumor with High Proliferative Activity and Tumor Suppressor P53 Expression

    Directory of Open Access Journals (Sweden)

    Maher Kurdi

    2014-01-01

    Full Text Available Background. The synchronous development of two primary brain tumors of distinct cell of origin in close proximity or in contact with each other is extremely rare. We present the first case of collision tumor with two histological distinct tumors. Case Presentation. A 54-year-old woman presented with progressive atypical left facial pain and numbness for 8 months. MRI of the brain showed left middle cranial fossa heterogeneous mass extending into the infratemporal fossa. At surgery, a distinct but intermingled intra- and extradural tumor was demonstrated which was completely removed through left orbitozygomatic-temporal craniotomy. Histopathological examination showed that the tumor had two distinct components: malignant nerve sheath tumor of the trigeminal nerve and temporal lobe anaplastic astrocytoma. Proliferative activity and expressed tumor protein 53 (TP53 gene mutations were demonstrated in both tumors. Conclusions. We describe the first case of malignant trigeminal nerve sheath tumor (MTNST and anaplastic astrocytoma in collision and discuss the possible hypothesis of this rare occurrence. We propose that MTNST, with TP53 mutation, have participated in the formation of anaplastic astrocytoma, or vice versa.

  17. First-line nitrosourea-based chemotherapy in symptomatic non-resectable supratentorial pure low-grade astrocytomas.

    Science.gov (United States)

    Frenay, M P; Fontaine, D; Vandenbos, F; Lebrun, C

    2005-09-01

    At the present time, there are no proven beneficial effects of chemotherapy (CT) for the treatment of pure low-grade astrocytomas. Brain radiotherapy (RT) still remains the standard treatment in order to reduce or delay tumor progression or symptoms, despite possible long-term neurologic complications. We report 10 patients, with histologically proven pure low-grade fibrillary astrocytomas, to which we administered a first-line nitrosourea-based CT. All patients were symptomatic with pharmaco-resistant epilepsy or neurologic symptoms, and had been rejected for neurosurgical resection. All patients with epilepsy had a clinical improvement with reduction in seizure frequency and 60% became seizure-free. CT was well tolerated; all patients developed myelosuppression with 40% of grade III/IV hematotoxicity. Seven were alive at the time of writing with a mean follow-up of 6.5 years (3.5-12) from first recorded symptoms. The three deceased patients died 7.5, 7.5, and 8.5 years from first symptoms. These results demonstrate that some patients with symptomatic non-resectable fibrillary low-grade astrocytomas can be treated with up-front CT to improve their neurologic status. This report suggests that benefits of CT on symptoms, survival, and quality of life should be prospectively compared with RT.

  18. Surgical Management of Pilocytic Astrocytoma of the Optic Nerve: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Ifeoluwa Apanisile

    2017-01-01

    Full Text Available Optic nerve astrocytomas (ONAs are frequent types of optic nerve gliomas (ONGs, which can affect the visual pathway. An 18-year-old male patient was admitted to our department with right-sided intraorbital/retrobulbar swelling, which progressively grew over several months. Clinical examination showed right-sided diplopia, mydriasis, low visual acuity (0.4, exophthalmus (3 cm, epiphora, and severe retrobulbar pain. There was a family history of high-grade (IV astrocytomas in which two of the family members died due to the disease. Preoperative MRI scan revealed a soft tissue mass around the retrobulbar area of the right eye with intact orbital bony walls. Surgery was performed whereby it was dissected freely from the muscles and was separated from the optic nerve and the globe. Histopathologic analysis confirmed a benign astrocytoma. The follow-up examination revealed no recurrent or residual tumor. A systemic review of the literature indicates that early diagnosis and experienced multidisciplinary management are required in case of unilateral, resectable forms of ONAs with no distant metastasis, in order to provide a long-time survival of patients. Surgical intervention of unilateral ONAs is a relatively safe procedure, allowing complete or partial tumor removal with minimal morbidity and low recurrence rate.

  19. Combined value of susceptibility weighted imaging and dynamic susceptibility-weighted contrast-enhanced MR perfusion-weighted imaging in brain astrocytoma grading

    International Nuclear Information System (INIS)

    Wang Xiaochun; Zhang Hui; Qin Jiangbo; Wang Le; Wu Xiaofeng

    2012-01-01

    Objective: To assess the value of combination of susceptibility weighted imaging (SWI) and dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion-weighted magnetic resonance imaging in astrocytoma grading. Methods: SWI and DSC scans were performed in 82 patients with pathologically confirmed astrocytoma. The patient group consisted of grade Ⅱ (15), grade Ⅲ (10), and grade Ⅳ (57). The intratumoral susceptibility signal intensity (ITSS) and relative cerebral blood volume (rCBV) max were used to determine the grade of astrocytomas by Kruskal Wallis test, Welch test, Spearman correlation coefficients, Pearson correlation coefficients, and receiver operating characteristic curve (ROC)statistic methods. Results: There were no ITSS in 14 cases of low-grade astrocytomas, the degree of ITSS were grade 1 to 3 in anaplastic astrocytomas, the degree of ITSS were grade 3 in all of the glioblastomas, the degree of ITSS were significant difference in all grades (H=71.96, P<0.01). rCBV max in grade Ⅱ, grade Ⅲ and grade Ⅳ astrocytomas were 1.26 ± 0.42, 3.59 ± 2.09 and 8.34 ± 1.16 respectively, rCBV max were significant difference in all grades (F'=681.72, P<0.01). ITSS showed significant correlation with rCBV max (r=0.72, P<0.01) and tumor grades (r=0.89, P<0.01), and rCBV and tumor grades showed significant correlation (r=0.78, P<0.01). Area under the ROC curve application SWI, DSC, SWI and DSC in differentiation of the grade Ⅱ and grade Ⅲ astrocytomas were 0.99, 0.93, 1.00, differentiate grade Ⅲ from grade Ⅳ were 0.70, 0.94, 0.94, and differentiate high-grade from low-grade astrocytomas were 1.00, 0.99, 1.00. Conclusions: ITSS is helpful to determine the grade of astrocytomas. The use of SWI in combination with DSC may improve the diagnostic accuracy of astrocytoma grading. (authors)

  20. The value of diffusion weighted imaging in differentiating intracranial tuberculomas from high-grade astrocytomas and metastases

    International Nuclear Information System (INIS)

    Peng Juan; Luo Tianyou; Lv Fajin; Fang Weidong; Wu Jingquan; Ouyang Yu; Li Yongmei

    2007-01-01

    Objective: To explore the value of diffusion weighted imaging (DWI) in differentiating intracranial tuberculomas from high-grade astrocytomas and metastases. Methods: The conventional MR imaging and DWI were performed in 50 eases (14 cases with intracranial tuberculomas, 15 cases with high- grade astrocytomas, and 21 cases with metastases) before treatment or operation. The mean apparent diffusion coefficient (ADC) values and relative apparent diffusion coefficient (rADC) values were calculated from the mass as well as from the peripheral edema regions of intracranial lesions. Results: The mean ADC values and rADC values were (1.2±0.2) x 10 -3 mm 2 ·s -1 and 1.6±0.3 in the mass of intracranial tuberculomas respectively; (0.8±0.1) x 10 -3 mm 2 ·s -1 and 1.1±0.1 in the parenehyma of high-grade astrocytomas; (0.8±0.1) x 10 -3 mm 2 ·s -1 and 1.0±0.2 in the parenchyma of metastases. There was significant difference of the mean ADC values (F=33.57, P -3 mm 2 ·s -1 and 2.5±0.2 in the peripheral edema regions of intracranial tuberculomas respectively; (1.4±0.2) x 10 -3 mm 2 ·s -1 and 1.8±0.3 in the peripheral edema regions of high-grade astrocytomas; and (1.9±0.2) x 10 -3 mm 2 ·s -1 and 2.3±0.5 in the peripheral edema regions of metastases. There was also significant difference in the mean ADC values (F23.17, P<0.01) or rADC values (F=5.94, P<0.01) among the peripheral edema regions of the three groups. Conclusion: The ADC values and rADC values are quite effective in differentiating intracranial tuberculoma from high-grade astrocytoma and metastasis. (authors)

  1. Methods for robustness programming

    NARCIS (Netherlands)

    Olieman, N.J.

    2008-01-01

    Robustness of an object is defined as the probability that an object will have properties as required. Robustness Programming (RP) is a mathematical approach for Robustness estimation and Robustness optimisation. An example in the context of designing a food product, is finding the best composition

  2. Robustness in laying hens

    NARCIS (Netherlands)

    Star, L.

    2008-01-01

    The aim of the project ‘The genetics of robustness in laying hens’ was to investigate nature and regulation of robustness in laying hens under sub-optimal conditions and the possibility to increase robustness by using animal breeding without loss of production. At the start of the project, a robust

  3. Malignant astrocytoma: hyperfractionated and standard radiotherapy with chemotherapy in a randomized prospective clinical trial

    International Nuclear Information System (INIS)

    Payne, D.G.; Simpson, W.J.; Keen, C.; Platts, M.E.

    1982-01-01

    A prospective randomized trial of 157 patients with malignant astrocytomas (Grade III or IV) was carried out at a single institution. The minimization technique ensured balanced distribution of prognostic factors between the treatment groups. All received oral lomustine (CCNU, 80 mg/m 2 ) six weekly and hydroxyurea (HU, 3.5 gm/m 2 over 5 days) three weekly, for one year or until recurrence, with doses adjusted for myelosuppression. Patients were randomized to daily (5000 rad in 25 fractions (fr) in 5 weeks) or Q3h (every 3 hours) Cobalt 60 irradiation (3600-4000 rad in 36-40 fr of 100 rad each, given 4 fr per day at 3-hour intervals over two weeks). Steroid therapy (up to 16 mg day dexamethasone) was permitted. Complications were moderate and equivalent in the two groups. No significant survival or toxicity differences were seen between the two groups. Age, initial performance status, and extent of surgical resection were found to be significant (P<0.01) prognostic factors for survival. Median survival of the whole group was 48 weeks with a minimum follow-up of one year. There was no advantage to large radiation fields. The hyperfractionation and daily regimes had similar efficacy and toxicity. Hyperfractionation with chemotherapy offers a useful alternative approach in the management of this disease

  4. Cytotoxicity Effects of Different Surfactant Molecules Conjugated to Carbon Nanotubes on Human Astrocytoma Cells

    Science.gov (United States)

    Dong, Lifeng; Witkowski, Colette M.; Craig, Michael M.; Greenwade, Molly M.; Joseph, Katherine L.

    2009-12-01

    Phase contrast and epifluorescence microscopy were utilized to monitor morphological changes in human astrocytoma cells during a time-course exposure to single-walled carbon nanotube (SWCNT) conjugates with different surfactants and to investigate sub-cellular distribution of the nanotube conjugates, respectively. Experimental results demonstrate that cytotoxicity of the nanotube/surfactant conjugates is related to the toxicity of surfactant molecules attached on the nanotube surfaces. Both sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) are toxic to cells. Exposure to CNT/SDS conjugates (0.5 mg/mL) for less than 5 min caused changes in cell morphology resulting in a distinctly spherical shape compared to untreated cells. In contrast, sodium cholate (SC) and CNT/SC did not affect cell morphology, proliferation, or growth. These data indicate that SC is an environmentally friendly surfactant for the purification and dispersion of SWCNTs. Epifluorescence microscopy analysis of CNT/DNA conjugates revealed distribution in the cytoplasm of cells and did not show adverse effects on cell morphology, proliferation, or viability during a 72-h incubation. These observations suggest that the SWCNTs could be used as non-viral vectors for diagnostic and therapeutic molecules across the blood-brain barrier to the brain and the central nervous system.

  5. Low-grade astrocytoma: surgical outcomes in eloquent versus non-eloquent brain areas

    Directory of Open Access Journals (Sweden)

    André de Macedo Bianco

    2013-01-01

    Full Text Available A retrospective study of 81 patients with low-grade astrocytoma (LGA comparing the efficacy of aggressive versus less aggressive surgery in eloquent and non-eloquent brain areas was conducted. Extent of surgical resection was analyzed to assess overall survival (OS and progression- free survival (PFS. Degree of tumor resection was classified as gross total resection (GTR, subtotal resection (STR or biopsy. GTR, STR and biopsy in patients with tumors in non-eloquent areas were performed in 31, 48 and 21% subjects, whereas in patients with tumors in eloquent areas resections were 22.5, 35 and 42.5%. Overall survival was 4.7 and 1.9 years in patients with tumors in non-eloquent brain areas submitted to GTR/STR and biopsy (p=0.013, whereas overall survival among patients with tumors in eloquent area was 4.5 and 2.1 years (p=0.33. Improved outcome for adult patients with LGA is predicted by more aggressive surgery in both eloquent and non-eloquent brain areas.

  6. A case of late presentation of precocious puberty due to pituitary astrocytoma

    Directory of Open Access Journals (Sweden)

    Fahimeh Soheilipour

    2015-08-01

    Full Text Available The importance of assessing precocious puberty, especially in boys, is not only due to the great complications it has for the affected patients, but also to the fatal underlying diseases. Therefore, children with central precocious puberty should first undergo neuroimaging. In this case study, we present a 9.5-year-old boy who was referred to Rasoul-e-Akram Medical Center with increased intracranial pressure, nausea/vomiting, and severe headache having begun three months earlier. The development of secondary sexual changes had started two years earlier, and had been neglected. His testes, penis, and pubic hair were at the fourth Tanner stage. He had elevated luteinizing and follicle stimulating hormones. Microscopic evaluation confirmed low-grade pilocytic astrocytoma WHO grade 1. Emergency brain surgery was conducted in which the brain was decompressed, and chemotherapy was started postoperatively. Two years after the surgery, he remains under chemotherapy, with obvious sexual maturation and a height of 154 cm. Training families and medical staff efficiently can help prevent the late diagnosis and treatment of precocious puberty and, as a result, help patients in their social life.

  7. Rapid increase in cystic volume of an anaplastic astrocytoma misdiagnosed as neurocysticercosis: A case report

    Science.gov (United States)

    Li, Hong-Jiang; Han, Hong-Xiu; Feng, Dong-Fu

    2016-01-01

    Reports describing a rapid increase in the cystic volume of anaplastic astrocytoma (AA) in a short time frame are rare. The present study reports the case of a 68-year-old male who was admitted to the No. 9 People's Hospital, Shanghai Jiaotong University School of Medicine (Shanghai, China), with a small cystic brain lesion and positive immunological testing for cysticercosis. Head magnetic resonance imaging (MRI) showed a cystic lesion, 6 mm in diameter, in the left frontal lobe. Neurocysticercosis was suspected and the patient was treated with a clinical trial of albendazole and steroids. A period of 25 days later, the patient's condition had deteriorated, and MRI revealed a cystic lesion in the left frontal lobe; thereafter, the cystic lesion was removed and a diagnosis of AA was established. The tumor was soft, ivory white and gelatinous due to myxoid degeneration. In this case, tumor-related angiogenesis and microvascular extravasation (blood-brain barrier disruption) may have been the main cause of the rapid increase in the cystic volume in such a short time frame. The similarity of the glioma and cysticercus antigens may have been the cause of the positive reactions in the cystic fluid. The present study reports the rare occurrence of a rapid increase of cystic volume and potential diagnostic difficulties. PMID:27698865

  8. The Characteristics of Astrocytomas and Oligodendrogliomas Are Caused by Two Distinct and Interchangeable Signaling Formats

    Directory of Open Access Journals (Sweden)

    Chengkai Dai

    2005-04-01

    Full Text Available Chronic platelet-derived growth factor (PDGF signaling in glial progenitors leads to the formation of oligodendrogliomas in mice, whereas chronic combined Ras and Akt signaling leads to astrocytomas. Different histologies of these tumors imply that the pathways activated by these two oncogenic stimulations are different, and that the apparent lineage of the tumor cells may result from specific signaling activity. Therefore, we have investigated the signaling effects of PDGF in culture and in gliomas in vivo. In culture, PDGF transiently activates ERK1/2 and Akt, and subsequently elevates p21 and PCNA expression similar to chronic PDGF autocrine signaling in cultured astrocytes and PDGF-induced oligodendrogliomas in vivo. Culture experiments show that autocrine PDGF stimulation, and combined active Ras and Akt generate signaling patterns that are in some ways mutually exclusive. Furthermore, forced Akt activity in the context of chronic PDGF stimulation results in cells with an astrocytic differentiation pattern both in culture and in vivo. These data imply that these two interconvertible signaling motifs are distinct in mice and lead to gliomas resembling the two major glioma histologies found in humans. The ability of signaling activity to convert tumor cells from one lineage to another presents a mechanism for the development of tumors apparently comprised of cells from multiple lineages.

  9. Effectiveness of interferon-beta and temozolomide combination therapy against temozolomide-refractory recurrent anaplastic astrocytoma

    Directory of Open Access Journals (Sweden)

    Arai Hajime

    2007-08-01

    Full Text Available Abstract Background Malignant gliomas recur even after extensive surgery and chemo-radiotherapy. Although a relatively novel chemotherapeutic agent, temozolomide (TMZ, has demonstrated promising activity against recurrent glioma, the effects last only a few months and drug resistance develops thereafter in most cases. Induction of O6-methylguanine-DNA methyltransferase (MGMT in tumors is considered to be responsible for resistance to TMZ. Interferon-beta has been reported to suppress MGMT in an experimental glioma model. Here we report a patient with TMZ-refractory anaplastic astrocytoma (AA who was treated successfully with a combination of interferon-beta and TMZ. Case presentation A patient with recurrent AA after radiation-chemotherapy and stereotactic radiotherapy was treated with TMZ. After 6 cycles, the tumor became refractory to TMZ, and the patient was treated with interferon-beta at 3 × 106 international units/body, followed by 5 consecutive days of 200 mg/m2 TMZ in cycles of 28 days. After the second cycle the tumor decreased in size by 50% (PR. The tumor showed further shrinkage after 8 months and the patient's KPS improved from 70% to 100%. The immunohistochemical study of the initial tumor specimen confirmed positive MGMT protein expression. Conclusion It is considered that interferon-beta pre-administration increased the TMZ sensitivity of the glioma, which had been refractory to TMZ monotherapy.

  10. TREATMENT OF PROGRESSION OF DIFFUSE ASTROCYTOMA BY HERBAL MEDICINE: CASE REPORT.

    Science.gov (United States)

    Trogrlić, Ivo; Trogrlić, Dragan; Trogrlić, Zoran

    2016-01-01

    The paper presents the results of the use of phytotherapy in a 33-year-old woman who, after finishing the oncological treatment of diffuse astrocytoma, had tumour progression. Phytotherapy was introduced after the tumour had progressed. It consisted of 4 types of herbal medicine which the subject was taking in form of tea once a day at regular intervals. The patient started phytotherapy along with temozolomide, which was the only oncological treatment she was under after the tumour had progressed. Following the finished chemotherapy, the patient continued the treatment with herbal medicine only. She regularly took phytotherapy without interruption and to the fullest extent for 30 months, and the results of treatment were monitored by periodic scanning using nuclear magnetic resonance technique. The control scanning that was conducted after the end of combined treatment with temozolomide and phytotherapy showed tumour regression. The patient continued with phytotherapy after finishing chemotherapy and, during the following 24 months, it was the sole treatment option. In that period, the regression of the tumour continued, until a control examination 30 months after the introduction of phytotherapy showed no clinical and radiological signs of tumour. The results presented in this research paper clearly indicate the potential of phytotherapy in the treatment of some types of brain tumours. A complete regression of tumour following the treatment with nothing but herbal medicine offers support for such claim. Future research should demonstrate the effectiveness of phytotherapy, as a supplementary form of brain tumour treatment, and the results of this research should be compared with the existing information on the effectiveness of the protocols currently used in the treatment of these types of tumour.

  11. Apoptosis and telomeres shortening related to HIV-1 induced oxidative stress in an astrocytoma cell line

    Directory of Open Access Journals (Sweden)

    Mollace Vincenzo

    2009-05-01

    Full Text Available Abstract Background Oxidative stress plays a key role in the neuropathogenesis of Human Immunodeficiency Virus-1 (HIV-1 infection causing apoptosis of astroglia cells and neurons. Recent data have shown that oxidative stress is also responsible for the acceleration of human fibroblast telomere shortening in vitro. In the present study we analyzed the potential relations occurring between free radicals formation and telomere length during HIV-1 mediated astroglial death. Results To this end, U373 human astrocytoma cells have been directly exposed to X4-using HIV-1IIIB strain, for 1, 3 or 5 days and treated (where requested with N-acetylcysteine (NAC, a cysteine donor involved in the synthesis of glutathione (GSH, a cellular antioxidant and apoptosis has been evaluated by FACS analysis. Quantitative-FISH (Q-FISH has been employed for studying the telomere length while intracellular reduced/oxidized glutathione (GSH/GSSG ratio has been determined by High-Performance Liquid Chromatography (HPLC. Incubation of U373 with HIV-1IIIB led to significant induction of cellular apoptosis that was reduced in the presence of 1 mM NAC. Moreover, NAC improved the GSH/GSSG, a sensitive indicator of oxidative stress, that significantly decreased after HIV-1IIIB exposure in U373. Analysis of telomere length in HIV-1 exposed U373 showed a statistically significant telomere shortening, that was completely reverted in NAC-treated U373. Conclusion Our results support the role of HIV-1-mediated oxidative stress in astrocytic death and the importance of antioxidant compounds in preventing these cellular damages. Moreover, these data indicate that the telomere structure, target for oxidative damage, could be the key sensor of cell apoptosis induced by oxidative stress after HIV infection.

  12. Surgical resection of grade II astrocytomas in the superior frontal gyrus.

    Science.gov (United States)

    Peraud, Aurelia; Meschede, Magnus; Eisner, Wilhelm; Ilmberger, Josef; Reulen, Hans-Jürgen

    2002-05-01

    Surgery in the superior frontal gyrus partially involving the supplementary motor area (SMA) may be followed by contralateral transient weakness and aphasia initially indistinguishable from damage to the primary motor cortex. However, recovery is different, and SMA deficits may resolve completely within days to weeks. No study has assessed the distinct postoperative deficits after tumor resection in the SMA on a homogeneous patient group. Twenty-four patients with World Health Organization Grade II astrocytomas in the superior frontal gyrus consecutively treated by surgery were studied. Degree and duration of postoperative deficits were evaluated according to tumor location and boundaries via magnetic resonance imaging scans, intraoperative neuromonitoring results, and extent of tumor resection. Postoperatively, motor deficits were evident in 21 of 24 and speech deficits in 9 of 12 patients. Motor function quickly recovered in 11 and speech function in 3 patients. None of the 12 patients in whom the posterior tumor resection line was at a distance of more than 0.5 cm from the precentral sulcus experienced persistent motor deficits. Eight of these patients developed typical SMA syndrome with transient initiation difficulties. Seven of 12 patients in whom the tumor extended to the precentral sulcus still had motor deficits at the 12-month follow-up assessment. Surgery for Grade II gliomas in the superior frontal gyrus is more likely to result in permanent morbidity when the resection is performed at a distance of less than 0.5 cm from the precentral gyrus or positive stimulation points. Therefore, cortical mapping of motor and speech function, in critical cases under local anesthesia with the patient as his or her own monitor, is recommended; resection should be tailored to obtain good functional outcome and maintain quality of life.

  13. A dangerous liaison: Leptin and sPLA2-IIA join forces to induce proliferation and migration of astrocytoma cells.

    Directory of Open Access Journals (Sweden)

    Rubén Martín

    Full Text Available Glioblastoma, the most aggressive type of primary brain tumour, shows worse prognosis linked to diabetes or obesity persistence. These pathologies are chronic inflammatory conditions characterized by altered profiles of inflammatory mediators, including leptin and secreted phospholipase A2-IIA (sPLA2-IIA. Both proteins, in turn, display diverse pro-cancer properties in different cell types, including astrocytes. Herein, to understand the underlying relationship between obesity and brain tumors, we investigated the effect of leptin, alone or in combination with sPLA2-IIA on astrocytoma cell functions. sPLA2-IIA induced up-regulation of leptin receptors in 1321N1 human astrocytoma cells. Leptin, as well as sPLA2-IIA, increased growth and migration in these cells, through activation/phosphorylation of key proteins of survival cascades. Leptin, at concentrations with minimal or no activating effects on astrocytoma cells, enhanced growth and migration promoted by low doses of sPLA2-IIA. sPLA2-IIA alone induced a transient phosphorylation pattern in the Src/ERK/Akt/mTOR/p70S6K/rS6 pathway through EGFR transactivation, and co-addition of leptin resulted in a sustained phosphorylation of these signaling regulators. Mechanistically, EGFR transactivation and tyrosine- and serine/threonine-protein phosphatases revealed a key role in this leptin-sPLA2-IIA cross-talk. This cooperative partnership between both proteins was also found in primary astrocytes. These findings thus indicate that the adipokine leptin, by increasing the susceptibility of cells to inflammatory mediators, could contribute to worsen the prognosis of tumoral and neurodegenerative processes, being a potential mediator of some obesity-related medical complications.

  14. The inhibitory effect of CIL-102 on the growth of human astrocytoma cells is mediated by the generation of reactive oxygen species and induction of ERK1/2 MAPK

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Chih-Chuan [Institute of Nursing and Department of Nursing, Chang Gung University of Science and Technology, Chronic Diseases and Health Promotion Research Center, CGUST, Taiwan (China); Institute of Basic Medicine Science, National Cheng Kung University, Tainan, Taiwan (China); Kuo, Hsing-Chun [Institute of Nursing and Department of Nursing, Chang Gung University of Science and Technology, Chronic Diseases and Health Promotion Research Center, CGUST, Taiwan (China); Cheng, Ho-Chen [Department of General Education, Chang Gung University of Science and Technology, CGUST, Taiwan (China); Wang, Ting-Chung [Department of Neurosurgery, Chang Gung Memorial Hospital, Chia-Yi Center, Chiayi, Taiwan (China); Graduate Institute of Clinical Medical Sciences, Chang Gung University, Gueishan, Taiwan (China); Sze, Chun-I, E-mail: szec@mail.ncku.edu.tw [Institute of Basic Medicine Science, Department of Cell Biology and Anatomy and Pathology, National Cheng Kung University, Tainan, Taiwan (China)

    2012-08-15

    CIL-102 (1-[4-(furo[2,3-b]quinolin-4-ylamino)phenyl]ethanone) is the major active agent of the alkaloid derivative of Camptotheca acuminata, with multiple pharmacological activities, including anticancer effects and promotion of apoptosis. The mechanism by which CIL-102 inhibits growth remains poorly understood in human astrocytoma cells. Herein, we investigated the molecular mechanisms by which CIL-102 affects the generation of reactive oxygen species (ROS) and cell cycle G2/M arrest in glioma cells. Treatment of U87 cells with 1.0 μM CIL-102 resulted in phosphorylation of extracellular signal-related kinase (ERK1/2), downregulation of cell cycle-related proteins (cyclin A, cyclin B, cyclin D1, and cdk1), and phosphorylation of cdk1Tyr{sup 15} and Cdc25cSer{sup 216}. Furthermore, treatment with the ERK1/2 inhibitor PD98059 abolished CIL-102-induced Cdc25cSer{sup 216} expression and reversed CIL-102-inhibited cdk1 activation. In addition, N-acetyl cysteine (NAC), an ROS scavenger, blocked cell cycle G2/M arrest and phosphorylation of ERK1/2 and Cdc25cSer{sup 216} in U87 cells. CIL-102-mediated ERK1/2 and ROS production, and cell cycle arrest were blocked by treatment with specific inhibitors. In conclusion, we have identified a novel CIL-102-inhibited proliferation in U87 cells by activating the ERK1/2 and Cdc25cSer{sup 216} cell cycle-related proteins and inducing ROS production; this might be a new mechanism in human astrocytoma cells. -- Highlights: ► We show the effects of CIL-102 on the G2/M arrest of human astrocytoma cells. ► ROS and the Ras/ERK1/2 triggering pathways are involved in the CIL-102 treatment. ► CIL-102 induces sustained activation of ERK1/2 and Cdc25c and ROS are required.

  15. The inhibitory effect of CIL-102 on the growth of human astrocytoma cells is mediated by the generation of reactive oxygen species and induction of ERK1/2 MAPK

    International Nuclear Information System (INIS)

    Teng, Chih-Chuan; Kuo, Hsing-Chun; Cheng, Ho-Chen; Wang, Ting-Chung; Sze, Chun-I

    2012-01-01

    CIL-102 (1-[4-(furo[2,3-b]quinolin-4-ylamino)phenyl]ethanone) is the major active agent of the alkaloid derivative of Camptotheca acuminata, with multiple pharmacological activities, including anticancer effects and promotion of apoptosis. The mechanism by which CIL-102 inhibits growth remains poorly understood in human astrocytoma cells. Herein, we investigated the molecular mechanisms by which CIL-102 affects the generation of reactive oxygen species (ROS) and cell cycle G2/M arrest in glioma cells. Treatment of U87 cells with 1.0 μM CIL-102 resulted in phosphorylation of extracellular signal-related kinase (ERK1/2), downregulation of cell cycle-related proteins (cyclin A, cyclin B, cyclin D1, and cdk1), and phosphorylation of cdk1Tyr 15 and Cdc25cSer 216 . Furthermore, treatment with the ERK1/2 inhibitor PD98059 abolished CIL-102-induced Cdc25cSer 216 expression and reversed CIL-102-inhibited cdk1 activation. In addition, N-acetyl cysteine (NAC), an ROS scavenger, blocked cell cycle G2/M arrest and phosphorylation of ERK1/2 and Cdc25cSer 216 in U87 cells. CIL-102-mediated ERK1/2 and ROS production, and cell cycle arrest were blocked by treatment with specific inhibitors. In conclusion, we have identified a novel CIL-102-inhibited proliferation in U87 cells by activating the ERK1/2 and Cdc25cSer 216 cell cycle-related proteins and inducing ROS production; this might be a new mechanism in human astrocytoma cells. -- Highlights: ► We show the effects of CIL-102 on the G2/M arrest of human astrocytoma cells. ► ROS and the Ras/ERK1/2 triggering pathways are involved in the CIL-102 treatment. ► CIL-102 induces sustained activation of ERK1/2 and Cdc25c and ROS are required.

  16. Robust multivariate analysis

    CERN Document Server

    J Olive, David

    2017-01-01

    This text presents methods that are robust to the assumption of a multivariate normal distribution or methods that are robust to certain types of outliers. Instead of using exact theory based on the multivariate normal distribution, the simpler and more applicable large sample theory is given.  The text develops among the first practical robust regression and robust multivariate location and dispersion estimators backed by theory.   The robust techniques  are illustrated for methods such as principal component analysis, canonical correlation analysis, and factor analysis.  A simple way to bootstrap confidence regions is also provided. Much of the research on robust multivariate analysis in this book is being published for the first time. The text is suitable for a first course in Multivariate Statistical Analysis or a first course in Robust Statistics. This graduate text is also useful for people who are familiar with the traditional multivariate topics, but want to know more about handling data sets with...

  17. Phytometabolite Dehydroleucodine Induces Cell Cycle Arrest, Apoptosis, and DNA Damage in Human Astrocytoma Cells through p73/p53 Regulation.

    Directory of Open Access Journals (Sweden)

    Natalia Bailon-Moscoso

    Full Text Available Accumulating evidence supports the idea that secondary metabolites obtained from medicinal plants (phytometabolites may be important contributors in the development of new chemotherapeutic agents to reduce the occurrence or recurrence of cancer. Our study focused on Dehydroleucodine (DhL, a sesquiterpene found in the provinces of Loja and Zamora-Chinchipe. In this study, we showed that DhL displayed cytostatic and cytotoxic activities on the human cerebral astrocytoma D384 cell line. With lactone isolated from Gynoxys verrucosa Wedd, a medicinal plant from Ecuador, we found that DhL induced cell death in D384 cells by triggering cell cycle arrest and inducing apoptosis and DNA damage. We further found that the cell death resulted in the increased expression of CDKN1A and BAX proteins. A marked induction of the levels of total TP73 and phosphorylated TP53, TP73, and γ-H2AX proteins was observed in D384 cells exposed to DhL, but no increase in total TP53 levels was detected. Overall these studies demonstrated the marked effect of DhL on the diminished survival of human astrocytoma cells through the induced expression of TP73 and phosphorylation of TP73 and TP53, suggesting their key roles in the tumor cell response to DhL treatment.

  18. Phytometabolite Dehydroleucodine Induces Cell Cycle Arrest, Apoptosis, and DNA Damage in Human Astrocytoma Cells through p73/p53 Regulation.

    Science.gov (United States)

    Bailon-Moscoso, Natalia; González-Arévalo, Gabriela; Velásquez-Rojas, Gabriela; Malagon, Omar; Vidari, Giovanni; Zentella-Dehesa, Alejandro; Ratovitski, Edward A; Ostrosky-Wegman, Patricia

    2015-01-01

    Accumulating evidence supports the idea that secondary metabolites obtained from medicinal plants (phytometabolites) may be important contributors in the development of new chemotherapeutic agents to reduce the occurrence or recurrence of cancer. Our study focused on Dehydroleucodine (DhL), a sesquiterpene found in the provinces of Loja and Zamora-Chinchipe. In this study, we showed that DhL displayed cytostatic and cytotoxic activities on the human cerebral astrocytoma D384 cell line. With lactone isolated from Gynoxys verrucosa Wedd, a medicinal plant from Ecuador, we found that DhL induced cell death in D384 cells by triggering cell cycle arrest and inducing apoptosis and DNA damage. We further found that the cell death resulted in the increased expression of CDKN1A and BAX proteins. A marked induction of the levels of total TP73 and phosphorylated TP53, TP73, and γ-H2AX proteins was observed in D384 cells exposed to DhL, but no increase in total TP53 levels was detected. Overall these studies demonstrated the marked effect of DhL on the diminished survival of human astrocytoma cells through the induced expression of TP73 and phosphorylation of TP73 and TP53, suggesting their key roles in the tumor cell response to DhL treatment.

  19. Estimation of radiotherapy and MCNU versus radiotherapy and MCNU plus interferon-[beta] for the treatment of anaplastic astrocytoma

    Energy Technology Data Exchange (ETDEWEB)

    Kiya, Katsuzo; Uozumi, Tohru; Kurisu, Kaoru; Ogasawara, Hidenori; Sugiyama, Kazuhiko; Maeda, Hitoshi; Harada, Kunyu (Hiroshima Univ. (Japan). School of Medicine)

    1993-02-01

    The efficacy of radiotherapy and MCNU (MR) was estimated in comparison with radiotherapy and MCNU plus interferon-[beta] (IMR) in 25 patients with anaplastic astrocytoma. The MR group received irradiation with 50[approx]60 Gy and intravenous administration of 2 mg/kg of MCNU on the initial day of irradiation and following every 6[approx]8 weeks interval. The IMR group also received the same regimen in addition to intravenous infusion of 2 x 10[sup 6] IU/m[sup 2] of interferon-[beta] for 5 serial days every eight weeks and following once every two weeks. There were no significant differences between the two groups in terms of background. The response rates of MR and IMR group were 38.5% and 66.7%, respectively. The times to tumor progression (TTP) in the two groups were 11.9[+-]5.8 months and 13.6[+-]7.7 months, respectively. Thus, IMR therapy seems to be more efficacious for patients with anaplastic astrocytoma than MR therapy, but further trials are necessary. (author).

  20. Robustness of Structures

    DEFF Research Database (Denmark)

    Faber, Michael Havbro; Vrouwenvelder, A.C.W.M.; Sørensen, John Dalsgaard

    2011-01-01

    In 2005, the Joint Committee on Structural Safety (JCSS) together with Working Commission (WC) 1 of the International Association of Bridge and Structural Engineering (IABSE) organized a workshop on robustness of structures. Two important decisions resulted from this workshop, namely...... ‘COST TU0601: Robustness of Structures’ was initiated in February 2007, aiming to provide a platform for exchanging and promoting research in the area of structural robustness and to provide a basic framework, together with methods, strategies and guidelines enhancing robustness of structures...... the development of a joint European project on structural robustness under the COST (European Cooperation in Science and Technology) programme and the decision to develop a more elaborate document on structural robustness in collaboration between experts from the JCSS and the IABSE. Accordingly, a project titled...

  1. Robust Growth Determinants

    OpenAIRE

    Doppelhofer, Gernot; Weeks, Melvyn

    2011-01-01

    This paper investigates the robustness of determinants of economic growth in the presence of model uncertainty, parameter heterogeneity and outliers. The robust model averaging approach introduced in the paper uses a flexible and parsi- monious mixture modeling that allows for fat-tailed errors compared to the normal benchmark case. Applying robust model averaging to growth determinants, the paper finds that eight out of eighteen variables found to be significantly related to economic growth ...

  2. Robust Programming by Example

    OpenAIRE

    Bishop , Matt; Elliott , Chip

    2011-01-01

    Part 2: WISE 7; International audience; Robust programming lies at the heart of the type of coding called “secure programming”. Yet it is rarely taught in academia. More commonly, the focus is on how to avoid creating well-known vulnerabilities. While important, that misses the point: a well-structured, robust program should anticipate where problems might arise and compensate for them. This paper discusses one view of robust programming and gives an example of how it may be taught.

  3. What is it to be sturdy (robust)?

    DEFF Research Database (Denmark)

    Nielsen, Niss Skov; Zwisler, Lars Pagter; Bojsen, Ann Kristina Mikkelsen

    Purpose: This paper intends to give a first insight into the concept of being "sturdy/robust"; To develop and test a Danish model of how to measure sturdi-ness/robustness; To test the scale's ability to identify people in emergency situa-tions who have high risk of developing psychological illness....

  4. Errantum: Treatment of human astrocytoma U87 cells with silicon dioxide nanoparticles lowers their survival and alters their expression of mitochondrial and cell signaling proteins

    Directory of Open Access Journals (Sweden)

    Lai JCK

    2010-12-01

    Full Text Available Lai JCK, Ananthakrishnan G, Jandhyam S, et al. Treatment of human astrocytoma U87 cells with silicon dioxide nanoparticles lowers their survival and alters their expression of mitochondrial and cell signaling proteins. Int J Nanomedicine. 2010;5:715–723.The wrong image was used in Figure 5 on page 719.

  5. The microRNA and messengerRNA profile of the RNA-induced silencing complex in human primary astrocyte and astrocytoma cells.

    Science.gov (United States)

    Moser, Joanna J; Fritzler, Marvin J

    2010-10-18

    GW/P bodies are cytoplasmic ribonucleoprotein-rich foci involved in microRNA (miRNA)-mediated messenger RNA (mRNA) silencing and degradation. The mRNA regulatory functions within GW/P bodies are mediated by GW182 and its binding partner hAgo2 that bind miRNA in the RNA-induced silencing complex (RISC). To date there are no published reports of the profile of miRNA and mRNA targeted to the RISC or a comparison of the RISC-specific miRNA/mRNA profile differences in malignant and non-malignant cells. RISC mRNA and miRNA components were profiled by microarray analysis of malignant human U-87 astrocytoma cells and its non-malignant counterpart, primary human astrocytes. Total cell RNA as well as RNA from immunoprecipitated RISC was analyzed. The novel findings were fourfold: (1) miRNAs were highly enriched in astrocyte RISC compared to U-87 astrocytoma RISC, (2) astrocytoma and primary astrocyte cells each contained unique RISC miRNA profiles as compared to their respective cellular miRNA profiles, (3) miR-195, 10b, 29b, 19b, 34a and 455-3p levels were increased and the miR-181b level was decreased in U-87 astrocytoma RISC as compared to astrocyte RISC, and (4) the RISC contained decreased levels of mRNAs in primary astrocyte and U-87 astrocytoma cells. The observation that miR-34a and miR-195 levels were increased in the RISC of U-87 astrocytoma cells suggests an oncogenic role for these miRNAs. Differential regulation of mRNAs by specific miRNAs is evidenced by the observation that three miR34a-targeted mRNAs and two miR-195-targeted mRNAs were downregulated while one miR-195-targeted mRNA was upregulated. Biological pathway analysis of RISC mRNA components suggests that the RISC plays a pivotal role in malignancy and other conditions. This study points to the importance of the RISC and ultimately GW/P body composition and function in miRNA and mRNA deregulation in astrocytoma cells and possibly in other malignancies.

  6. The microRNA and messengerRNA profile of the RNA-induced silencing complex in human primary astrocyte and astrocytoma cells.

    Directory of Open Access Journals (Sweden)

    Joanna J Moser

    2010-10-01

    Full Text Available GW/P bodies are cytoplasmic ribonucleoprotein-rich foci involved in microRNA (miRNA-mediated messenger RNA (mRNA silencing and degradation. The mRNA regulatory functions within GW/P bodies are mediated by GW182 and its binding partner hAgo2 that bind miRNA in the RNA-induced silencing complex (RISC. To date there are no published reports of the profile of miRNA and mRNA targeted to the RISC or a comparison of the RISC-specific miRNA/mRNA profile differences in malignant and non-malignant cells.RISC mRNA and miRNA components were profiled by microarray analysis of malignant human U-87 astrocytoma cells and its non-malignant counterpart, primary human astrocytes. Total cell RNA as well as RNA from immunoprecipitated RISC was analyzed. The novel findings were fourfold: (1 miRNAs were highly enriched in astrocyte RISC compared to U-87 astrocytoma RISC, (2 astrocytoma and primary astrocyte cells each contained unique RISC miRNA profiles as compared to their respective cellular miRNA profiles, (3 miR-195, 10b, 29b, 19b, 34a and 455-3p levels were increased and the miR-181b level was decreased in U-87 astrocytoma RISC as compared to astrocyte RISC, and (4 the RISC contained decreased levels of mRNAs in primary astrocyte and U-87 astrocytoma cells.The observation that miR-34a and miR-195 levels were increased in the RISC of U-87 astrocytoma cells suggests an oncogenic role for these miRNAs. Differential regulation of mRNAs by specific miRNAs is evidenced by the observation that three miR34a-targeted mRNAs and two miR-195-targeted mRNAs were downregulated while one miR-195-targeted mRNA was upregulated. Biological pathway analysis of RISC mRNA components suggests that the RISC plays a pivotal role in malignancy and other conditions. This study points to the importance of the RISC and ultimately GW/P body composition and function in miRNA and mRNA deregulation in astrocytoma cells and possibly in other malignancies.

  7. Comparing Four Instructional Techniques for Promoting Robust Knowledge

    Science.gov (United States)

    Richey, J. Elizabeth; Nokes-Malach, Timothy J.

    2015-01-01

    Robust knowledge serves as a common instructional target in academic settings. Past research identifying characteristics of experts' knowledge across many domains can help clarify the features of robust knowledge as well as ways of assessing it. We review the expertise literature and identify three key features of robust knowledge (deep,…

  8. Effects of γ-radiation on cell growth, cell cycle and promoter methylation of 22 cell cycle genes in the 1321NI astrocytoma cell line.

    Science.gov (United States)

    Alghamian, Yaman; Abou Alchamat, Ghalia; Murad, Hossam; Madania, Ammar

    2017-09-01

    DNA damage caused by radiation initiates biological responses affecting cell fate. DNA methylation regulates gene expression and modulates DNA damage pathways. Alterations in the methylation profiles of cell cycle regulating genes may control cell response to radiation. In this study we investigated the effect of ionizing radiation on the methylation levels of 22 cell cycle regulating genes in correlation with gene expression in 1321NI astrocytoma cell line. 1321NI cells were irradiated with 2, 5 or 10Gy doses then analyzed after 24, 48 and 72h for cell viability using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliu bromide) assay. Flow cytometry were used to study the effect of 10Gy irradiation on cell cycle. EpiTect Methyl II PCR Array was used to identify differentially methylated genes in irradiated cells. Changes in gene expression was determined by qPCR. Azacytidine treatment was used to determine whether DNA methylation affectes gene expression. Our results showed that irradiation decreased cell viability and caused cell cycle arrest at G2/M. Out of 22 genes tested, only CCNF and RAD9A showed some increase in DNA methylation (3.59% and 3.62%, respectively) after 10Gy irradiation, and this increase coincided with downregulation of both genes (by 4 and 2 fold, respectively). with azacytidine confirmed that expression of CCNF and RAD9A genes was regulated by methylation. 1321NI cell line is highly radioresistant and that irradiation of these cells with a 10Gy dose increases DNA methylation of CCNF and RAD9A genes. This dose down-regulates these genes, favoring G2/M arrest. Copyright © 2017 Medical University of Bialystok. Published by Elsevier B.V. All rights reserved.

  9. Subventricular zone predicts high velocity of tumor expansion and poor clinical outcome in patients with low grade astrocytoma.

    Science.gov (United States)

    Wen, Bing; Fu, Feixian; Hu, Liangbo; Cai, Qiuyi; Xie, Junshi

    2018-05-01

    The aim of this study is to clarify the association between subventricular zone (SVZ) involvement and velocity of diametric expansion(VDE) in patients with low-grade astrocytoma and also assessed the clinical outcome of those patients. A total of 168 adult patients with newly diagnosed supratentorial low-grade astrocytoma were studied retrospectively. There were 73 patients had SVZ involvement. Patients with SVZ involvement(7.16 ± 6.53 mm/y) had a higher VDE than patients without SVZ involvement(4.38 ± 5.35 mm/y). VDE was modeled as a categorical variable(<4, ≥4 and, <8, ≥8 and, <12, ≥12 mm/y). Logistic regression showed that SVZ involvement was associated with high VDE after adjusting by confounding variables. On the univariate analysis, the results showed that tumor involved with SVZ, VDE ≥ 4 mm/y, VDE ≥ 8 mm/y, and VDE ≥ 8 mm/y were significant predictors of a shorter OS, progression-free survival (PFS) and malignant progression-free survival (MFS)(all p <0.05). The categorical variables of VDE (<4 mm/y, ≥4 mm/y and, <8 mm/y, ≥8 mm/y and, <12 mm/y, ≥12 mm/y) were adjusted by confounding variables in multivariate analysis, respectively. The results indicated that VDE ≥ 8 mm/y, VDE ≥ 12 mm/y were worse prognostic factors for OS, while VDE ≥ 4 mm/y, VDE ≥ 8 mm/y and VDE ≥ 12 mm/y were related to shorter PFS and MFS. In addition, SVZ involvement was prognostic factors in predicting OS and PFS except MFS. Our results demonstrated that SVZ involvement predicted high VDE and worse clinical outcome, and high VDE was associated with poor prognosis in patients with low-grade astrocytoma. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Neuronavigation-guided intubated wake-up craniotomy for a patient with a brain astrocytoma

    Directory of Open Access Journals (Sweden)

    Wen-Kuei Fang

    2013-08-01

    Full Text Available Computer-assisted neuronavigation (an image-guided technique that facilitates brain tumor surgery reduces the risk of neurological morbidity. Postoperative neurological dysfunction is also minimized by performing intraoperative neurological testing during awake craniotomy with proper surgical resection of a brain tumor. However, when the patient's airway is not secured, an awake craniotomy can be hazardous if emergent intubation is necessary. The present report describes a young man with a brain tumor who underwent neuronavigation-guided wake-up craniotomy and surgical resection of an astrocytoma. The patient was intubated throughout the course of the procedure, during which modified intraoperative neurological tests were performed for cortical mapping. The patient recovered well after the operation and without any neurological deficits.

  11. Robustness Beamforming Algorithms

    Directory of Open Access Journals (Sweden)

    Sajad Dehghani

    2014-04-01

    Full Text Available Adaptive beamforming methods are known to degrade in the presence of steering vector and covariance matrix uncertinity. In this paper, a new approach is presented to robust adaptive minimum variance distortionless response beamforming make robust against both uncertainties in steering vector and covariance matrix. This method minimize a optimization problem that contains a quadratic objective function and a quadratic constraint. The optimization problem is nonconvex but is converted to a convex optimization problem in this paper. It is solved by the interior-point method and optimum weight vector to robust beamforming is achieved.

  12. Association Study with 77 SNPs Confirms the Robust Role for the rs10830963/G of MTNR1B Variant and Identifies Two Novel Associations in Gestational Diabetes Mellitus Development.

    Directory of Open Access Journals (Sweden)

    Klara Rosta

    Full Text Available Genetic variation in human maternal DNA contributes to the susceptibility for development of gestational diabetes mellitus (GDM.We assessed 77 maternal single nucleotide gene polymorphisms (SNPs for associations with GDM or plasma glucose levels at OGTT in pregnancy.960 pregnant women (after dropouts 820: case/control: m99'WHO: 303/517, IADPSG: 287/533 were enrolled in two countries into this case-control study. After genomic DNA isolation the 820 samples were collected in a GDM biobank and assessed using KASP (LGC Genomics genotyping assay. Logistic regression risk models were used to calculate ORs according to IADPSG/m'99WHO criteria based on standard OGTT values.The most important risk alleles associated with GDM were rs10830963/G of MTNR1B (OR = 1.84/1.64 [IADPSG/m'99WHO], p = 0.0007/0.006, rs7754840/C (OR = 1.51/NS, p = 0.016 of CDKAL1 and rs1799884/T (OR = 1.4/1.56, p = 0.04/0.006 of GCK. The rs13266634/T (SLC30A8, OR = 0.74/0.71, p = 0.05/0.02 and rs7578326/G (LOC646736/IRS1, OR = 0.62/0.60, p = 0.001/0.006 variants were associated with lower risk to develop GDM. Carrying a minor allele of rs10830963 (MTNR1B; rs7903146 (TCF7L2; rs1799884 (GCK SNPs were associated with increased plasma glucose levels at routine OGTT.We confirmed the robust association of MTNR1B rs10830963/G variant with GDM binary and glycemic traits in this Caucasian case-control study. As novel associations we report the minor, G allele of the rs7578326 SNP in the LOC646736/IRS1 region as a significant and the rs13266634/T SNP (SLC30A8 as a suggestive protective variant against GDM development. Genetic susceptibility appears to be more preponderant in individuals who meet both the modified 99'WHO and the IADPSG GDM diagnostic criteria.

  13. Robustness Metrics: Consolidating the multiple approaches to quantify Robustness

    DEFF Research Database (Denmark)

    Göhler, Simon Moritz; Eifler, Tobias; Howard, Thomas J.

    2016-01-01

    robustness metrics; 3) Functional expectancy and dispersion robustness metrics; and 4) Probability of conformance robustness metrics. The goal was to give a comprehensive overview of robustness metrics and guidance to scholars and practitioners to understand the different types of robustness metrics...

  14. Defining robustness protocols: a method to include and evaluate robustness in clinical plans

    International Nuclear Information System (INIS)

    McGowan, S E; Albertini, F; Lomax, A J; Thomas, S J

    2015-01-01

    We aim to define a site-specific robustness protocol to be used during the clinical plan evaluation process. Plan robustness of 16 skull base IMPT plans to systematic range and random set-up errors have been retrospectively and systematically analysed. This was determined by calculating the error-bar dose distribution (ebDD) for all the plans and by defining some metrics used to define protocols aiding the plan assessment. Additionally, an example of how to clinically use the defined robustness database is given whereby a plan with sub-optimal brainstem robustness was identified. The advantage of using different beam arrangements to improve the plan robustness was analysed. Using the ebDD it was found range errors had a smaller effect on dose distribution than the corresponding set-up error in a single fraction, and that organs at risk were most robust to the range errors, whereas the target was more robust to set-up errors. A database was created to aid planners in terms of plan robustness aims in these volumes. This resulted in the definition of site-specific robustness protocols. The use of robustness constraints allowed for the identification of a specific patient that may have benefited from a treatment of greater individuality. A new beam arrangement showed to be preferential when balancing conformality and robustness for this case. The ebDD and error-bar volume histogram proved effective in analysing plan robustness. The process of retrospective analysis could be used to establish site-specific robustness planning protocols in proton therapy. These protocols allow the planner to determine plans that, although delivering a dosimetrically adequate dose distribution, have resulted in sub-optimal robustness to these uncertainties. For these cases the use of different beam start conditions may improve the plan robustness to set-up and range uncertainties. (paper)

  15. Defining robustness protocols: a method to include and evaluate robustness in clinical plans

    Science.gov (United States)

    McGowan, S. E.; Albertini, F.; Thomas, S. J.; Lomax, A. J.

    2015-04-01

    We aim to define a site-specific robustness protocol to be used during the clinical plan evaluation process. Plan robustness of 16 skull base IMPT plans to systematic range and random set-up errors have been retrospectively and systematically analysed. This was determined by calculating the error-bar dose distribution (ebDD) for all the plans and by defining some metrics used to define protocols aiding the plan assessment. Additionally, an example of how to clinically use the defined robustness database is given whereby a plan with sub-optimal brainstem robustness was identified. The advantage of using different beam arrangements to improve the plan robustness was analysed. Using the ebDD it was found range errors had a smaller effect on dose distribution than the corresponding set-up error in a single fraction, and that organs at risk were most robust to the range errors, whereas the target was more robust to set-up errors. A database was created to aid planners in terms of plan robustness aims in these volumes. This resulted in the definition of site-specific robustness protocols. The use of robustness constraints allowed for the identification of a specific patient that may have benefited from a treatment of greater individuality. A new beam arrangement showed to be preferential when balancing conformality and robustness for this case. The ebDD and error-bar volume histogram proved effective in analysing plan robustness. The process of retrospective analysis could be used to establish site-specific robustness planning protocols in proton therapy. These protocols allow the planner to determine plans that, although delivering a dosimetrically adequate dose distribution, have resulted in sub-optimal robustness to these uncertainties. For these cases the use of different beam start conditions may improve the plan robustness to set-up and range uncertainties.

  16. Robustness of Structures

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2008-01-01

    This paper describes the background of the robustness requirements implemented in the Danish Code of Practice for Safety of Structures and in the Danish National Annex to the Eurocode 0, see (DS-INF 146, 2003), (DS 409, 2006), (EN 1990 DK NA, 2007) and (Sørensen and Christensen, 2006). More...... frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure combined with increased requirements to efficiency in design and execution followed by increased risk of human errors has made the need of requirements to robustness of new structures essential....... According to Danish design rules robustness shall be documented for all structures in high consequence class. The design procedure to document sufficient robustness consists of: 1) Review of loads and possible failure modes / scenarios and determination of acceptable collapse extent; 2) Review...

  17. Robustness of structures

    DEFF Research Database (Denmark)

    Vrouwenvelder, T.; Sørensen, John Dalsgaard

    2009-01-01

    After the collapse of the World Trade Centre towers in 2001 and a number of collapses of structural systems in the beginning of the century, robustness of structural systems has gained renewed interest. Despite many significant theoretical, methodical and technological advances, structural...... of robustness for structural design such requirements are not substantiated in more detail, nor have the engineering profession been able to agree on an interpretation of robustness which facilitates for its uantification. A European COST action TU 601 on ‘Robustness of structures' has started in 2007...... by a group of members of the CSS. This paper describes the ongoing work in this action, with emphasis on the development of a theoretical and risk based quantification and optimization procedure on the one side and a practical pre-normative guideline on the other....

  18. Robust Approaches to Forecasting

    OpenAIRE

    Jennifer Castle; David Hendry; Michael P. Clements

    2014-01-01

    We investigate alternative robust approaches to forecasting, using a new class of robust devices, contrasted with equilibrium correction models. Their forecasting properties are derived facing a range of likely empirical problems at the forecast origin, including measurement errors, implulses, omitted variables, unanticipated location shifts and incorrectly included variables that experience a shift. We derive the resulting forecast biases and error variances, and indicate when the methods ar...

  19. Robustness - theoretical framework

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Rizzuto, Enrico; Faber, Michael H.

    2010-01-01

    More frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure combined with increased requirements to efficiency in design and execution followed by increased risk of human errors has made the need of requirements to robustness of new struct...... of this fact sheet is to describe a theoretical and risk based framework to form the basis for quantification of robustness and for pre-normative guidelines....

  20. Qualitative Robustness in Estimation

    Directory of Open Access Journals (Sweden)

    Mohammed Nasser

    2012-07-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Times New Roman","serif";} Qualitative robustness, influence function, and breakdown point are three main concepts to judge an estimator from the viewpoint of robust estimation. It is important as well as interesting to study relation among them. This article attempts to present the concept of qualitative robustness as forwarded by first proponents and its later development. It illustrates intricacies of qualitative robustness and its relation with consistency, and also tries to remove commonly believed misunderstandings about relation between influence function and qualitative robustness citing some examples from literature and providing a new counter-example. At the end it places a useful finite and a simulated version of   qualitative robustness index (QRI. In order to assess the performance of the proposed measures, we have compared fifteen estimators of correlation coefficient using simulated as well as real data sets.

  1. Properties of human blood monocytes. I. CD91 expression and log orthogonal light scatter provide a robust method to identify monocytes that is more accurate than CD14 expression.

    Science.gov (United States)

    Hudig, Dorothy; Hunter, Kenneth W; Diamond, W John; Redelman, Doug

    2014-03-01

    This study was designed to improve identification of human blood monocytes by using antibodies to molecules that occur consistently on all stages of monocyte development and differentiation. We examined blood samples from 200 healthy adults without clinically diagnosed immunological abnormalities by flow cytometry (FCM) with multiple combinations of antibodies and with a hematology analyzer (Beckman LH750). CD91 (α2 -macroglobulin receptor) was expressed only by monocytes and to a consistent level among subjects [mean median fluorescence intensity (MFI) = 16.2 ± 3.2]. Notably, only 85.7 ± 5.82% of the CD91(+) monocytes expressed high levels of the classical monocyte marker CD14, with some CD91(+) CD16(+) cells having negligible CD14, indicating that substantial FCM under-counts will occur when monocytes are identified by high CD14. CD33 (receptor for sialyl conjugates) was co-expressed with CD91 on monocytes but CD33 expression varied by nearly ten-fold among subjects (mean MFI = 17.4 ± 7.7). In comparison to FCM analyses, the hematology analyzer systematically over-counted monocytes and eosinophils while lymphocyte and neutrophil differential values generally agreed with FCM methods. CD91 is a better marker to identify monocytes than CD14 or CD33. Furthermore, FCM (with anti-CD91) identifies monocytes better than a currently used clinical CBC instrument. Use of anti-CD91 together with anti-CD14 and anti-CD16 supports the identification of the diagnostically significant monocyte populations with variable expression of CD14 and CD16. Copyright © 2013 Clinical Cytometry Society.

  2. Robustness in econometrics

    CERN Document Server

    Sriboonchitta, Songsak; Huynh, Van-Nam

    2017-01-01

    This book presents recent research on robustness in econometrics. Robust data processing techniques – i.e., techniques that yield results minimally affected by outliers – and their applications to real-life economic and financial situations are the main focus of this book. The book also discusses applications of more traditional statistical techniques to econometric problems. Econometrics is a branch of economics that uses mathematical (especially statistical) methods to analyze economic systems, to forecast economic and financial dynamics, and to develop strategies for achieving desirable economic performance. In day-by-day data, we often encounter outliers that do not reflect the long-term economic trends, e.g., unexpected and abrupt fluctuations. As such, it is important to develop robust data processing techniques that can accommodate these fluctuations.

  3. Robust Manufacturing Control

    CERN Document Server

    2013-01-01

    This contributed volume collects research papers, presented at the CIRP Sponsored Conference Robust Manufacturing Control: Innovative and Interdisciplinary Approaches for Global Networks (RoMaC 2012, Jacobs University, Bremen, Germany, June 18th-20th 2012). These research papers present the latest developments and new ideas focusing on robust manufacturing control for global networks. Today, Global Production Networks (i.e. the nexus of interconnected material and information flows through which products and services are manufactured, assembled and distributed) are confronted with and expected to adapt to: sudden and unpredictable large-scale changes of important parameters which are occurring more and more frequently, event propagation in networks with high degree of interconnectivity which leads to unforeseen fluctuations, and non-equilibrium states which increasingly characterize daily business. These multi-scale changes deeply influence logistic target achievement and call for robust planning and control ...

  4. Robust plasmonic substrates

    DEFF Research Database (Denmark)

    Kostiučenko, Oksana; Fiutowski, Jacek; Tamulevicius, Tomas

    2014-01-01

    Robustness is a key issue for the applications of plasmonic substrates such as tip-enhanced Raman spectroscopy, surface-enhanced spectroscopies, enhanced optical biosensing, optical and optoelectronic plasmonic nanosensors and others. A novel approach for the fabrication of robust plasmonic...... substrates is presented, which relies on the coverage of gold nanostructures with diamond-like carbon (DLC) thin films of thicknesses 25, 55 and 105 nm. DLC thin films were grown by direct hydrocarbon ion beam deposition. In order to find the optimum balance between optical and mechanical properties...

  5. Robust Self Tuning Controllers

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    1985-01-01

    The present thesis concerns robustness properties of adaptive controllers. It is addressed to methods for robustifying self tuning controllers with respect to abrupt changes in the plant parameters. In the thesis an algorithm for estimating abruptly changing parameters is presented. The estimator...... has several operation modes and a detector for controlling the mode. A special self tuning controller has been developed to regulate plant with changing time delay.......The present thesis concerns robustness properties of adaptive controllers. It is addressed to methods for robustifying self tuning controllers with respect to abrupt changes in the plant parameters. In the thesis an algorithm for estimating abruptly changing parameters is presented. The estimator...

  6. Middle Temporal Gyrus Versus Inferior Temporal Gyrus Transcortical Approaches to High-Grade Astrocytomas in the Mediobasal Temporal Lobe: A Comparison of Outcomes, Functional Restoration, and Surgical Considerations.

    Science.gov (United States)

    Quinones-Hinojosa, Alfredo; Raza, Shaan M; Ahmed, Ishrat; Rincon-Torroella, Jordina; Chaichana, Kaisorn; Olivi, Alessandro

    2017-01-01

    High-grade astrocytomas of the mesial temporal lobe may pose surgical challenges. Several approaches (trans-sylvian, subtemporal, and transcortical) have been designed to circumnavigate the critical neurovascular structures and white fiber tracts that surround this area. Considering the paucity of literature on the transcortical approach for these lesions, we describe our institutional experience with transcortical approaches to Grade III/IV astrocytomas in the mesial temporal lobe. Between 1999 and 2009, 23 patients underwent surgery at the Johns Hopkins Medical Institutions for Grade III/IV astrocytomas involving the mesial temporal lobe (without involvement of the temporal neocortex). Clinical notes, operative records, and imaging were reviewed. Thirteen patients had tumors in the dominant hemisphere. All patients underwent surgery via a transcortical approach (14 via the inferior temporal gyrus and 9 via the middle temporal gyrus). Gross total resection was obtained in 92 % of the cohort. Neurological outcomes were: clinically significant stroke (2 patients), new visual deficits (2 patients), new speech deficit (1 patient); seizure control (53 %). In comparison to reported results in the literature for the transylvian and subtemporal approaches, the transcortical approach may provide the access necessary for a gross total resection with minimal neurological consequences. In our series of patients, there was no statistically significant difference in outcomes between the middle temporal gyrus versus the inferior temporal gyrus trajectories.

  7. Robust surgery loading

    NARCIS (Netherlands)

    Hans, Elias W.; Wullink, Gerhard; van Houdenhoven, Mark; Kazemier, Geert

    2008-01-01

    We consider the robust surgery loading problem for a hospital’s operating theatre department, which concerns assigning surgeries and sufficient planned slack to operating room days. The objective is to maximize capacity utilization and minimize the risk of overtime, and thus cancelled patients. This

  8. Robustness Envelopes of Networks

    NARCIS (Netherlands)

    Trajanovski, S.; Martín-Hernández, J.; Winterbach, W.; Van Mieghem, P.

    2013-01-01

    We study the robustness of networks under node removal, considering random node failure, as well as targeted node attacks based on network centrality measures. Whilst both of these have been studied in the literature, existing approaches tend to study random failure in terms of average-case

  9. The effect of everolimus on renal angiomyolipoma in pediatric patients with tuberous sclerosis being treated for subependymal giant cell astrocytoma.

    Science.gov (United States)

    Bissler, John J; Franz, David N; Frost, Michael D; Belousova, Elena; Bebin, E Martina; Sparagana, Steven; Berkowitz, Noah; Ridolfi, Antonia; Kingswood, J Christopher

    2018-01-01

    Patients with tuberous sclerosis complex (TSC) often have multiple TSC-associated hamartomas, particularly in the brain and kidney. This was a post hoc analysis of pediatric patients being treated for subependymal giant cell astrocytomas (SEGAs) during the phase 3, randomized, double-blind, placebo-controlled EXIST-1 trial. Patients were initially randomly assigned to receive everolimus 4.5 mg/m 2 /day (target blood trough 5-15 mg/dl) or placebo and could continue in an open-label extension phase. Angiomyolipoma response rates were analyzed in patients aged 20% increase in kidney volume from nadir, and angiomyolipoma-related bleeding ≥ grade 2. Tolerability was also assessed. Overall, this analysis included 33 patients. Renal angiomyolipoma response was achieved by 75.8% of patients (95% confidence interval, 57.7-88.9%), with sustained mean reductions in renal angiomyolipoma volume over nearly 4 years of treatment. In addition, most (≥80%) achieved clinically relevant reductions in angiomyolipoma volume (≥50%), beginning at week 24 and continuing for the remainder of the study. Everolimus was generally well tolerated in this subgroup, with most adverse events being grade 1 or 2 in severity. Although everolimus is currently not indicated for this use, this analysis from EXIST-1 demonstrates its long-term efficacy and safety for the treatment of renal angiomyolipoma in pediatric patients undergoing treatment for TSC-associated SEGA.

  10. Long-term results of postoperative radiotherapy in adult patients with incompletely excised infratentorial low grade astrocytoma

    International Nuclear Information System (INIS)

    Pluta, E.; Glinski, B.; Szpytma, T.; Nowak-Sadzikowska, J.

    2002-01-01

    lnfratentorial low grade astrocytoma (ILGA) occurs rarely in adult patients and accounts for about 3% of all intracranial tumors.The basic method of treatment for ILGA is surgery. Complete resection results in high local control rate and the role of postoperative irradiation in management of partially resected tumors is not clearly determined. The aim of this study was to evaluate the efficacy of postoperative irradiation in adult patients with incompletely excised ILGA. Between 1975 and 1995, thirty one adult patients with incompletely excised ILGA received postoperative irradiation with curative intent. All patients were treated with megavoltage gamma rays ( 60C o). The total dose ranged from 50 to 60 Gy (mean; 54 Gy) and was delivered with daily fraction of 1.8-2 Gy. The treatment volume covered the tumor being area with a margin of 1-2 cm. Tolerance to treatment has been found to be good in 30 patients (97%). The overall 15-year actuarial survival rate was 62% in the entire group. Young patients, up to twenty years of age achieved a 15-year overall actuarial survival rate of 85%, older patients - 46%. This difference was statistically significant (p =0. 0205). Conventionally fractionated postoperative radiotherapy with doses of 50 to 60 Gy may improve long term results of adult patients with ILGA after uncomplete resection. Age is a significant prognostic factor - young patients, up to twenty years of age, show best survival. (author)

  11. A robust classic.

    Science.gov (United States)

    Kutzner, Florian; Vogel, Tobias; Freytag, Peter; Fiedler, Klaus

    2011-01-01

    In the present research, we argue for the robustness of illusory correlations (ICs, Hamilton & Gifford, 1976) regarding two boundary conditions suggested in previous research. First, we argue that ICs are maintained under extended experience. Using simulations, we derive conflicting predictions. Whereas noise-based accounts predict ICs to be maintained (Fielder, 2000; Smith, 1991), a prominent account based on discrepancy-reducing feedback learning predicts ICs to disappear (Van Rooy et al., 2003). An experiment involving 320 observations with majority and minority members supports the claim that ICs are maintained. Second, we show that actively using the stereotype to make predictions that are met with reward and punishment does not eliminate the bias. In addition, participants' operant reactions afford a novel online measure of ICs. In sum, our findings highlight the robustness of ICs that can be explained as a result of unbiased but noisy learning.

  12. Container Materials, Fabrication And Robustness

    International Nuclear Information System (INIS)

    Dunn, K.; Louthan, M.; Rawls, G.; Sindelar, R.; Zapp, P.; Mcclard, J.

    2009-01-01

    The multi-barrier 3013 container used to package plutonium-bearing materials is robust and thereby highly resistant to identified degradation modes that might cause failure. The only viable degradation mechanisms identified by a panel of technical experts were pressurization within and corrosion of the containers. Evaluations of the container materials and the fabrication processes and resulting residual stresses suggest that the multi-layered containers will mitigate the potential for degradation of the outer container and prevent the release of the container contents to the environment. Additionally, the ongoing surveillance programs and laboratory studies should detect any incipient degradation of containers in the 3013 storage inventory before an outer container is compromised.

  13. Automatically identifying scatter in fluorescence data using robust techniques

    DEFF Research Database (Denmark)

    Engelen, S.; Frosch, Stina; Hubert, M.

    2007-01-01

    as input data for three different PARAFAC methods. Firstly inserting missing values in the scatter regions are tested, secondly an interpolation of the scatter regions is performed and finally the scatter regions are down-weighted. These results show that the PARAFAC method to choose after scatter...

  14. Robust Airline Schedules

    OpenAIRE

    Eggenberg, Niklaus; Salani, Matteo; Bierlaire, Michel

    2010-01-01

    Due to economic pressure industries, when planning, tend to focus on optimizing the expected profit or the yield. The consequence of highly optimized solutions is an increased sensitivity to uncertainty. This generates additional "operational" costs, incurred by possible modifications of the original plan to be performed when reality does not reflect what was expected in the planning phase. The modern research trend focuses on "robustness" of solutions instead of yield or profit. Although ro...

  15. Design principles for robust oscillatory behavior.

    Science.gov (United States)

    Castillo-Hair, Sebastian M; Villota, Elizabeth R; Coronado, Alberto M

    2015-09-01

    Oscillatory responses are ubiquitous in regulatory networks of living organisms, a fact that has led to extensive efforts to study and replicate the circuits involved. However, to date, design principles that underlie the robustness of natural oscillators are not completely known. Here we study a three-component enzymatic network model in order to determine the topological requirements for robust oscillation. First, by simulating every possible topological arrangement and varying their parameter values, we demonstrate that robust oscillators can be obtained by augmenting the number of both negative feedback loops and positive autoregulations while maintaining an appropriate balance of positive and negative interactions. We then identify network motifs, whose presence in more complex topologies is a necessary condition for obtaining oscillatory responses. Finally, we pinpoint a series of simple architectural patterns that progressively render more robust oscillators. Together, these findings can help in the design of more reliable synthetic biomolecular networks and may also have implications in the understanding of other oscillatory systems.

  16. The Variation Management Framework (VMF) for Robust Design

    DEFF Research Database (Denmark)

    Howard, Thomas J.; Ebro, Martin; Eifler, Tobias

    2014-01-01

    Robust Design is an approach to reduce the effects of variation. There are numerous tools,methods and models associated with robust design, however, there is both a lack of a processmodel formalising the step of a robust design process and a framework tying the models together.In this paper we pr...... in the market place and identifies areaswhere action can be taken against variation. An additional benefit of the framework is that itmakes the link between visual/sensory/perceptual robustness, product robustness, and productionvariation (Six Sigma)....

  17. Handling Occlusions for Robust Augmented Reality Systems

    Directory of Open Access Journals (Sweden)

    Maidi Madjid

    2010-01-01

    Full Text Available Abstract In Augmented Reality applications, the human perception is enhanced with computer-generated graphics. These graphics must be exactly registered to real objects in the scene and this requires an effective Augmented Reality system to track the user's viewpoint. In this paper, a robust tracking algorithm based on coded fiducials is presented. Square targets are identified and pose parameters are computed using a hybrid approach based on a direct method combined with the Kalman filter. An important factor for providing a robust Augmented Reality system is the correct handling of targets occlusions by real scene elements. To overcome tracking failure due to occlusions, we extend our method using an optical flow approach to track visible points and maintain virtual graphics overlaying when targets are not identified. Our proposed real-time algorithm is tested with different camera viewpoints under various image conditions and shows to be accurate and robust.

  18. Robust efficient video fingerprinting

    Science.gov (United States)

    Puri, Manika; Lubin, Jeffrey

    2009-02-01

    We have developed a video fingerprinting system with robustness and efficiency as the primary and secondary design criteria. In extensive testing, the system has shown robustness to cropping, letter-boxing, sub-titling, blur, drastic compression, frame rate changes, size changes and color changes, as well as to the geometric distortions often associated with camcorder capture in cinema settings. Efficiency is afforded by a novel two-stage detection process in which a fast matching process first computes a number of likely candidates, which are then passed to a second slower process that computes the overall best match with minimal false alarm probability. One key component of the algorithm is a maximally stable volume computation - a three-dimensional generalization of maximally stable extremal regions - that provides a content-centric coordinate system for subsequent hash function computation, independent of any affine transformation or extensive cropping. Other key features include an efficient bin-based polling strategy for initial candidate selection, and a final SIFT feature-based computation for final verification. We describe the algorithm and its performance, and then discuss additional modifications that can provide further improvement to efficiency and accuracy.

  19. Comparative non-cholinergic neurotoxic effects of paraoxon and diisopropyl fluorophosphate (DFP) on human neuroblastoma and astrocytoma cell lines

    International Nuclear Information System (INIS)

    Qian Yongchang; Venkatraj, Jijayanagaram; Barhoumi, Rola; Pal, Ranadip; Datta, Aniruddha; Wild, James R.; Tiffany-Castiglioni, Evelyn

    2007-01-01

    The objective of this study was to evaluate the comparative non-cholinergic neurotoxic effects of paraoxon, which is acutely neurotoxic, and diisopropyl fluorophosphate (DFP), which induces OPIDN, in the human neuroblastoma SY5Y and the human astrocytoma cell line CCF-STTG1. SY5Y cells have been studied extensively as a model for OP-induced neurotoxicity, but CCF cells have not previously been studied. We conducted a preliminary human gene array assay of OP-treated SY5Y cells in order to assess at the gene level whether these cells can distinguish between OP compounds that do and do not cause OPIDN. Paraoxon and DFP induced dramatically different profiles of gene expression. Two genes were upregulated and 13 downregulated by at least 2-fold in paraoxon-treated cells. In contrast, one gene was upregulated by DFP and none was downregulated at the 2-fold threshold. This finding is consistent with current and previous observations that SY5Y cells can distinguish between OPs that do or do not induce OPIDN. We also examined gene array results for possible novel target proteins or metabolic pathways for OP neurotoxicity. Protein levels of glucose regulated protein 78 (GRP78) revealed that paraoxon exposure at 3 μM for 24 h significantly reduced GRP78 levels by 30% in neuroblastoma cells, whereas DFP treatment had no effect. In comparison with SY5Y neuroblastoma cells, paraoxon and DFP (3 μM for 24 h) each significantly increased GRP78 levels by 23-24% in CCF astrocytoma cells. As we have previously evaluated intracellular changes in Ca 2+ levels in SY5Y cells, we investigated the effects of paraoxon and DFP on cellular Ca 2+ homeostasis in CCF by studying cytosolic and mitochondrial basal calcium levels. A significant decrease in the ratio of mitochondrial to cytosolic Ca 2+ fluorescence was detected in CCF cultures treated for either 1 or 3 days with 1, 3, 10, or 30 μM paraoxon. In contrast, treatment with DFP for 1 day had no significant effect on the ratio of

  20. Differentiation of hemangioblastomas from pilocytic astrocytomas using 3-T magnetic resonance perfusion-weighted imaging and MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    She, D.J.; Xing, Z.; Zeng, Z.; Cao, D.R. [First Affiliated Hospital of Fujian Medical University, Department of Radiology, Fuzhou, Fujian (China); Shang, X.Y. [University of California, San Diego, Department of Medicine and the Moores UCSD Cancer Center, La Jolla, CA (United States)

    2015-03-01

    Hemangioblastomas and pilocytic astrocytomas (PAs) present similar imaging features on conventional MR imaging, making differential diagnosis a challenge. The purpose of this study was to evaluate the usefulness of dynamic susceptibility-weighted contrast-enhanced perfusion-weighted imaging (DSC-PWI) and proton MR spectroscopic imaging in the differentiation of hemangioblastomas and PAs. A 3.0-T MR imaging unit was used to perform DSC-PWI and conventional MR imaging on 14 patients with hemangioblastomas and 22 patients with PAs. Four patients with hemangioblastomas and 10 PA patients also underwent proton MR spectroscopy. Parameters of relative peak height (rPH) and relative percentage of signal intensity recovery (rPSR) were acquired by DSC-PWI and variables of N-acetylaspasrtate (NAA)/creatine (Cr), choline (Cho)/Cr, and lactate-lipid (Lac-Lip)/Cr by MR spectroscopy. The sensitivity, specificity, and the area under the receiver operating characteristic curve of all analyzed parameters at respective cutoff values were determined. Higher rPH but lower rPSR values were detected in hemangioblastomas compared to PAs. The NAA/Cr ratio was significantly lower in hemangioblastomas compared with PAs. The threshold values ≥3.2 for rPH provide sensitivity, specificity, positive predictive values, and negative predictive values of 85.7, 95.5, 92.3, and 91.3 %, respectively, for differentiating hemangioblastomas from PAs. The optimal threshold values were ≤0.9 for rPSR and ≤1.5 for NAA/Cr ratios in tumor. Significantly higher rPH and lower NAA/Cr were seen in patients with hemangioblastomas when compared with PA patients, suggesting that DSC-PWI and proton MR spectroscopy are helpful in the characterization and differentiation of these two types of tumors. (orig.)

  1. Post-treatment changes of tumour perfusion parameters can help to predict survival in patients with high-grade astrocytoma

    Energy Technology Data Exchange (ETDEWEB)

    Sanz-Requena, Roberto; Marti-Bonmati, Luis [Hospital Quironsalud Valencia, Radiology Department, Valencia (Spain); Hospital Universitari i Politecnic La Fe, Grupo de Investigacion Biomedica en Imagen, Valencia (Spain); Revert-Ventura, Antonio J.; Salame-Gamarra, Fares [Hospital de Manises, Radiology Department, Manises (Spain); Garcia-Marti, Gracian [Hospital Quironsalud Valencia, Radiology Department, Valencia (Spain); Hospital Universitari i Politecnic La Fe, Grupo de Investigacion Biomedica en Imagen, Valencia (Spain); CIBER-SAM, Instituto de Salud Carlos III, Madrid (Spain); Perez-Girbes, Alexandre [Hospital Universitari i Politecnic La Fe, Grupo de Investigacion Biomedica en Imagen, Valencia (Spain); Molla-Olmos, Enrique [Hospital La Ribera, Radiology Department, Alzira (Spain)

    2017-08-15

    Vascular characteristics of tumour and peritumoral volumes of high-grade gliomas change with treatment. This work evaluates the variations of T2*-weighted perfusion parameters as overall survival (OS) predictors. Forty-five patients with histologically confirmed high-grade astrocytoma (8 grade III and 37 grade IV) were included. All patients underwent pre- and post-treatment T2*-weighted contrast-enhanced magnetic resonance (MR) imaging. Tumour, peritumoral and control volumes were segmented. Relative variations of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), K{sup trans-T2*}, k{sub ep-T2*}, v{sub e-T2*} and v{sub p-T2*} were calculated. Differences regarding tumour grade and surgical resection extension were evaluated with ANOVA tests. For each parameter, two groups were defined by non-supervised clusterisation. Survival analysis were performed on these groups. For the tumour region, the 90th percentile increase or stagnation of CBV was associated with shorter survival, while a decrease related to longer survival (393 ± 189 vs 594 ± 294 days; log-rank p = 0.019; Cox hazard-ratio, 2.31; 95% confidence interval [CI], 1.12-4.74). K{sup trans-T2*} showed similar results (414 ± 177 vs 553 ± 312 days; log-rank p = 0.037; hazard-ratio, 2.19; 95% CI, 1.03-4.65). The peritumoral area values showed no relationship with OS. Post-treatment variations of the highest CBV and K{sup trans-T2*} values in the tumour volume are predictive factors of OS in patients with high-grade gliomas. (orig.)

  2. The extrinsic and intrinsic apoptotic pathways are involved in manganese toxicity in rat astrocytoma C6 cells.

    Science.gov (United States)

    Alaimo, Agustina; Gorojod, Roxana M; Kotler, Mónica L

    2011-08-01

    Manganese (Mn) is a trace element known to be essential for maintaining the proper function and regulation of many biochemical and cellular reactions. However, chronic exposure to high levels of Mn in occupational or environmental settings can lead to its accumulation in the brain resulting in a degenerative brain disorder referred to as Manganism. Astrocytes are the main Mn store in the central nervous system and several lines of evidence implicate these cells as major players in the role of Manganism development. In the present study, we employed rat astrocytoma C6 cells as a sensitive experimental model for investigating molecular mechanisms involved in Mn neurotoxicity. Our results show that C6 cells undergo reactive oxygen species-mediated apoptotic cell death involving caspase-8 and mitochondrial-mediated pathways in response to Mn. Exposed cells exhibit typical apoptotic features, such as chromatin condensation, cell shrinkage, membrane blebbing, caspase-3 activation and caspase-specific cleavage of the endogenous substrate poly (ADP-ribose) polymerase. Participation of the caspase-8 dependent pathway was assessed by increased levels of FasL, caspase-8 activation and Bid cleavage. The involvement of the mitochondrial pathway was demonstrated by the disruption of the mitochondrial membrane potential, the opening of the mitochondrial permeability transition pore, cytochrome c release, caspase-9 activation and the increased mitochondrial levels of the pro-apoptotic Bcl-2 family proteins. In addition, our data also shows for the first time that mitochondrial fragmentation plays a relevant role in Mn-induced apoptosis. Taking together, these findings contribute to a deeper elucidation of the molecular signaling mechanisms underlying Mn-induced apoptosis. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. New solutions for NPP robustness improvement

    International Nuclear Information System (INIS)

    Wolski, Alexander

    2013-01-01

    Fukushima accident has triggered a major re-assessment of robustness of nuclear stations. First round of evaluations has been Finished. Improvement areas and strategies have been identified. Implementation of upgrades has started world-wide. New solutions can provide substantial benefits

  4. Robust Design of Sounds in Mechanical Mechanisms

    DEFF Research Database (Denmark)

    Boegedal Jensen, Annemette; Munch, Natasja; Howard, Thomas J.

    2015-01-01

    mechanism consisting of a toothed rack and a click arm. First several geometries of the teeth and the click arm’s head were investigated to identify the most robust and repeatable design. It was found that a flat surface in the valleys between the teeth is very beneficial in relation to repeatability...

  5. Robust automated knowledge capture.

    Energy Technology Data Exchange (ETDEWEB)

    Stevens-Adams, Susan Marie; Abbott, Robert G.; Forsythe, James Chris; Trumbo, Michael Christopher Stefan; Haass, Michael Joseph; Hendrickson, Stacey M. Langfitt

    2011-10-01

    This report summarizes research conducted through the Sandia National Laboratories Robust Automated Knowledge Capture Laboratory Directed Research and Development project. The objective of this project was to advance scientific understanding of the influence of individual cognitive attributes on decision making. The project has developed a quantitative model known as RumRunner that has proven effective in predicting the propensity of an individual to shift strategies on the basis of task and experience related parameters. Three separate studies are described which have validated the basic RumRunner model. This work provides a basis for better understanding human decision making in high consequent national security applications, and in particular, the individual characteristics that underlie adaptive thinking.

  6. Passion, Robustness and Perseverance

    DEFF Research Database (Denmark)

    Lim, Miguel Antonio; Lund, Rebecca

    2016-01-01

    Evaluation and merit in the measured university are increasingly based on taken-for-granted assumptions about the “ideal academic”. We suggest that the scholar now needs to show that she is passionate about her work and that she gains pleasure from pursuing her craft. We suggest that passion...... and pleasure achieve an exalted status as something compulsory. The scholar ought to feel passionate about her work and signal that she takes pleasure also in the difficult moments. Passion has become a signal of robustness and perseverance in a job market characterised by funding shortages, increased pressure...... way to demonstrate their potential and, crucially, their passion for their work. Drawing on the literature on technologies of governance, we reflect on what is captured and what is left out by these two evaluation instruments. We suggest that bibliometric analysis at the individual level is deeply...

  7. Robust Optical Flow Estimation

    Directory of Open Access Journals (Sweden)

    Javier Sánchez Pérez

    2013-10-01

    Full Text Available n this work, we describe an implementation of the variational method proposed by Brox etal. in 2004, which yields accurate optical flows with low running times. It has several benefitswith respect to the method of Horn and Schunck: it is more robust to the presence of outliers,produces piecewise-smooth flow fields and can cope with constant brightness changes. Thismethod relies on the brightness and gradient constancy assumptions, using the information ofthe image intensities and the image gradients to find correspondences. It also generalizes theuse of continuous L1 functionals, which help mitigate the effect of outliers and create a TotalVariation (TV regularization. Additionally, it introduces a simple temporal regularizationscheme that enforces a continuous temporal coherence of the flow fields.

  8. Robust Multimodal Dictionary Learning

    Science.gov (United States)

    Cao, Tian; Jojic, Vladimir; Modla, Shannon; Powell, Debbie; Czymmek, Kirk; Niethammer, Marc

    2014-01-01

    We propose a robust multimodal dictionary learning method for multimodal images. Joint dictionary learning for both modalities may be impaired by lack of correspondence between image modalities in training data, for example due to areas of low quality in one of the modalities. Dictionaries learned with such non-corresponding data will induce uncertainty about image representation. In this paper, we propose a probabilistic model that accounts for image areas that are poorly corresponding between the image modalities. We cast the problem of learning a dictionary in presence of problematic image patches as a likelihood maximization problem and solve it with a variant of the EM algorithm. Our algorithm iterates identification of poorly corresponding patches and re-finements of the dictionary. We tested our method on synthetic and real data. We show improvements in image prediction quality and alignment accuracy when using the method for multimodal image registration. PMID:24505674

  9. Robust snapshot interferometric spectropolarimetry.

    Science.gov (United States)

    Kim, Daesuk; Seo, Yoonho; Yoon, Yonghee; Dembele, Vamara; Yoon, Jae Woong; Lee, Kyu Jin; Magnusson, Robert

    2016-05-15

    This Letter describes a Stokes vector measurement method based on a snapshot interferometric common-path spectropolarimeter. The proposed scheme, which employs an interferometric polarization-modulation module, can extract the spectral polarimetric parameters Ψ(k) and Δ(k) of a transmissive anisotropic object by which an accurate Stokes vector can be calculated in the spectral domain. It is inherently strongly robust to the object 3D pose variation, since it is designed distinctly so that the measured object can be placed outside of the interferometric module. Experiments are conducted to verify the feasibility of the proposed system. The proposed snapshot scheme enables us to extract the spectral Stokes vector of a transmissive anisotropic object within tens of msec with high accuracy.

  10. International Conference on Robust Statistics

    CERN Document Server

    Filzmoser, Peter; Gather, Ursula; Rousseeuw, Peter

    2003-01-01

    Aspects of Robust Statistics are important in many areas. Based on the International Conference on Robust Statistics 2001 (ICORS 2001) in Vorau, Austria, this volume discusses future directions of the discipline, bringing together leading scientists, experienced researchers and practitioners, as well as younger researchers. The papers cover a multitude of different aspects of Robust Statistics. For instance, the fundamental problem of data summary (weights of evidence) is considered and its robustness properties are studied. Further theoretical subjects include e.g.: robust methods for skewness, time series, longitudinal data, multivariate methods, and tests. Some papers deal with computational aspects and algorithms. Finally, the aspects of application and programming tools complete the volume.

  11. Robust Instrumentation[Water treatment for power plant]; Robust Instrumentering

    Energy Technology Data Exchange (ETDEWEB)

    Wik, Anders [Vattenfall Utveckling AB, Stockholm (Sweden)

    2003-08-01

    Cementa Slite Power Station is a heat recovery steam generator (HRSG) with moderate steam data; 3.0 MPa and 420 deg C. The heat is recovered from Cementa, a cement industry, without any usage of auxiliary fuel. The Power station commenced operation in 2001. The layout of the plant is unusual, there are no similar in Sweden and very few world-wide, so the operational experiences are limited. In connection with the commissioning of the power plant a R and D project was identified with the objective to minimise the manpower needed for chemistry management of the plant. The lean chemistry management is based on robust instrumentation and chemical-free water treatment plant. The concept with robust instrumentation consists of the following components; choice of on-line instrumentation with a minimum of O and M and a chemical-free water treatment. The parameters are specific conductivity, cation conductivity, oxygen and pH. In addition to that, two fairly new on-line instruments were included; corrosion monitors and differential pH calculated from specific and cation conductivity. The chemical-free water treatment plant consists of softening, reverse osmosis and electro-deionisation. The operational experience shows that the cycle chemistry is not within the guidelines due to major problems with the operation of the power plant. These problems have made it impossible to reach steady state and thereby not viable to fully verify and validate the concept with robust instrumentation. From readings on the panel of the online analysers some conclusions may be drawn, e.g. the differential pH measurements have fulfilled the expectations. The other on-line analysers have been working satisfactorily apart from contamination with turbine oil, which has been noticed at least twice. The corrosion monitors seem to be working but the lack of trend curves from the mainframe computer system makes it hard to draw any clear conclusions. The chemical-free water treatment has met all

  12. Robustness Analyses of Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Hald, Frederik

    2013-01-01

    The robustness of structural systems has obtained a renewed interest arising from a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures, many mo...... with respect to robustness of timber structures and will discuss the consequences of such robustness issues related to the future development of timber structures.......The robustness of structural systems has obtained a renewed interest arising from a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures, many...... modern building codes consider the need for the robustness of structures and provide strategies and methods to obtain robustness. Therefore, a structural engineer may take necessary steps to design robust structures that are insensitive to accidental circumstances. The present paper summaries issues...

  13. Dynamics robustness of cascading systems.

    Directory of Open Access Journals (Sweden)

    Jonathan T Young

    2017-03-01

    Full Text Available A most important property of biochemical systems is robustness. Static robustness, e.g., homeostasis, is the insensitivity of a state against perturbations, whereas dynamics robustness, e.g., homeorhesis, is the insensitivity of a dynamic process. In contrast to the extensively studied static robustness, dynamics robustness, i.e., how a system creates an invariant temporal profile against perturbations, is little explored despite transient dynamics being crucial for cellular fates and are reported to be robust experimentally. For example, the duration of a stimulus elicits different phenotypic responses, and signaling networks process and encode temporal information. Hence, robustness in time courses will be necessary for functional biochemical networks. Based on dynamical systems theory, we uncovered a general mechanism to achieve dynamics robustness. Using a three-stage linear signaling cascade as an example, we found that the temporal profiles and response duration post-stimulus is robust to perturbations against certain parameters. Then analyzing the linearized model, we elucidated the criteria of when signaling cascades will display dynamics robustness. We found that changes in the upstream modules are masked in the cascade, and that the response duration is mainly controlled by the rate-limiting module and organization of the cascade's kinetics. Specifically, we found two necessary conditions for dynamics robustness in signaling cascades: 1 Constraint on the rate-limiting process: The phosphatase activity in the perturbed module is not the slowest. 2 Constraints on the initial conditions: The kinase activity needs to be fast enough such that each module is saturated even with fast phosphatase activity and upstream changes are attenuated. We discussed the relevance of such robustness to several biological examples and the validity of the above conditions therein. Given the applicability of dynamics robustness to a variety of systems, it

  14. Emergence of robustness in networks of networks

    Science.gov (United States)

    Roth, Kevin; Morone, Flaviano; Min, Byungjoon; Makse, Hernán A.

    2017-06-01

    A model of interdependent networks of networks (NONs) was introduced recently [Proc. Natl. Acad. Sci. (USA) 114, 3849 (2017), 10.1073/pnas.1620808114] in the context of brain activation to identify the neural collective influencers in the brain NON. Here we investigate the emergence of robustness in such a model, and we develop an approach to derive an exact expression for the random percolation transition in Erdös-Rényi NONs of this kind. Analytical calculations are in agreement with numerical simulations, and highlight the robustness of the NON against random node failures, which thus presents a new robust universality class of NONs. The key aspect of this robust NON model is that a node can be activated even if it does not belong to the giant mutually connected component, thus allowing the NON to be built from below the percolation threshold, which is not possible in previous models of interdependent networks. Interestingly, the phase diagram of the model unveils particular patterns of interconnectivity for which the NON is most vulnerable, thereby marking the boundary above which the robustness of the system improves with increasing dependency connections.

  15. Robust continuous clustering.

    Science.gov (United States)

    Shah, Sohil Atul; Koltun, Vladlen

    2017-09-12

    Clustering is a fundamental procedure in the analysis of scientific data. It is used ubiquitously across the sciences. Despite decades of research, existing clustering algorithms have limited effectiveness in high dimensions and often require tuning parameters for different domains and datasets. We present a clustering algorithm that achieves high accuracy across multiple domains and scales efficiently to high dimensions and large datasets. The presented algorithm optimizes a smooth continuous objective, which is based on robust statistics and allows heavily mixed clusters to be untangled. The continuous nature of the objective also allows clustering to be integrated as a module in end-to-end feature learning pipelines. We demonstrate this by extending the algorithm to perform joint clustering and dimensionality reduction by efficiently optimizing a continuous global objective. The presented approach is evaluated on large datasets of faces, hand-written digits, objects, newswire articles, sensor readings from the Space Shuttle, and protein expression levels. Our method achieves high accuracy across all datasets, outperforming the best prior algorithm by a factor of 3 in average rank.

  16. Robust Trust in Expert Testimony

    Directory of Open Access Journals (Sweden)

    Christian Dahlman

    2015-05-01

    Full Text Available The standard of proof in criminal trials should require that the evidence presented by the prosecution is robust. This requirement of robustness says that it must be unlikely that additional information would change the probability that the defendant is guilty. Robustness is difficult for a judge to estimate, as it requires the judge to assess the possible effect of information that the he or she does not have. This article is concerned with expert witnesses and proposes a method for reviewing the robustness of expert testimony. According to the proposed method, the robustness of expert testimony is estimated with regard to competence, motivation, external strength, internal strength and relevance. The danger of trusting non-robust expert testimony is illustrated with an analysis of the Thomas Quick Case, a Swedish legal scandal where a patient at a mental institution was wrongfully convicted for eight murders.

  17. Robust and distributed hypothesis testing

    CERN Document Server

    Gül, Gökhan

    2017-01-01

    This book generalizes and extends the available theory in robust and decentralized hypothesis testing. In particular, it presents a robust test for modeling errors which is independent from the assumptions that a sufficiently large number of samples is available, and that the distance is the KL-divergence. Here, the distance can be chosen from a much general model, which includes the KL-divergence as a very special case. This is then extended by various means. A minimax robust test that is robust against both outliers as well as modeling errors is presented. Minimax robustness properties of the given tests are also explicitly proven for fixed sample size and sequential probability ratio tests. The theory of robust detection is extended to robust estimation and the theory of robust distributed detection is extended to classes of distributions, which are not necessarily stochastically bounded. It is shown that the quantization functions for the decision rules can also be chosen as non-monotone. Finally, the boo...

  18. Robustness of IPTV business models

    NARCIS (Netherlands)

    Bouwman, H.; Zhengjia, M.; Duin, P. van der; Limonard, S.

    2008-01-01

    The final stage in the STOF method is an evaluation of the robustness of the design, for which the method provides some guidelines. For many innovative services, the future holds numerous uncertainties, which makes evaluating the robustness of a business model a difficult task. In this chapter, we

  19. Robustness Evaluation of Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2009-01-01

    Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure.......Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure....

  20. Robust statistical methods with R

    CERN Document Server

    Jureckova, Jana

    2005-01-01

    Robust statistical methods were developed to supplement the classical procedures when the data violate classical assumptions. They are ideally suited to applied research across a broad spectrum of study, yet most books on the subject are narrowly focused, overly theoretical, or simply outdated. Robust Statistical Methods with R provides a systematic treatment of robust procedures with an emphasis on practical application.The authors work from underlying mathematical tools to implementation, paying special attention to the computational aspects. They cover the whole range of robust methods, including differentiable statistical functions, distance of measures, influence functions, and asymptotic distributions, in a rigorous yet approachable manner. Highlighting hands-on problem solving, many examples and computational algorithms using the R software supplement the discussion. The book examines the characteristics of robustness, estimators of real parameter, large sample properties, and goodness-of-fit tests. It...

  1. Childhood Astrocytomas Treatment

    Science.gov (United States)

    ... the base of the brain. It controls body temperature, hunger, and thirst. Visual pathway : The group of ... the tumor may cause severe physical, emotional, or learning problems, a biopsy is done and more treatment ...

  2. Regulation of sonic hedgehog-GLI1 downstream target genes PTCH1, Cyclin D2, Plakoglobin, PAX6 and NKX2.2 and their epigenetic status in medulloblastoma and astrocytoma

    Directory of Open Access Journals (Sweden)

    Eberhart Charles G

    2010-11-01

    Full Text Available Abstract Background The Sonic hedgehog (Shh signaling pathway is critical for cell growth and differentiation. Impairment of this pathway can result in both birth defects and cancer. Despite its importance in cancer development, the Shh pathway has not been thoroughly investigated in tumorigenesis of brain tumors. In this study, we sought to understand the regulatory roles of GLI1, the immediate downstream activator of the Shh signaling pathway on its downstream target genes PTCH1, Cyclin D2, Plakoglobin, NKX2.2 and PAX6 in medulloblastoma and astrocytic tumors. Methods We silenced GLI1 expression in medulloblastoma and astrocytic cell lines by transfection of siRNA against GLI1. Subsequently, we performed RT-PCR and quantitative real time RT-PCR (qRT-PCR to assay the expression of downstream target genes PTCH1, Cyclin D2, Plakoglobin, NKX2.2 and PAX6. We also attempted to correlate the pattern of expression of GLI1 and its regulated genes in 14 cell lines and 41 primary medulloblastoma and astrocytoma tumor samples. We also assessed the methylation status of the Cyclin D2 and PTCH1 promoters in these 14 cell lines and 58 primary tumor samples. Results Silencing expression of GLI1 resulted up-regulation of all target genes in the medulloblastoma cell line, while only PTCH1 was up-regulated in astrocytoma. We also observed methylation of the cyclin D2 promoter in a significant number of astrocytoma cell lines (63% and primary astrocytoma tumor samples (32%, but not at all in any medulloblastoma samples. PTCH1 promoter methylation was less frequently observed than Cyclin D2 promoter methylation in astrocytomas, and not at all in medulloblastomas. Conclusions Our results demonstrate different regulatory mechanisms of Shh-GLI1 signaling. These differences vary according to the downstream target gene affected, the origin of the tissue, as well as epigenetic regulation of some of these genes.

  3. Regulation of sonic hedgehog-GLI1 downstream target genes PTCH1, Cyclin D2, Plakoglobin, PAX6 and NKX2.2 and their epigenetic status in medulloblastoma and astrocytoma

    International Nuclear Information System (INIS)

    Shahi, Mehdi H; Afzal, Mohammad; Sinha, Subrata; Eberhart, Charles G; Rey, Juan A; Fan, Xing; Castresana, Javier S

    2010-01-01

    The Sonic hedgehog (Shh) signaling pathway is critical for cell growth and differentiation. Impairment of this pathway can result in both birth defects and cancer. Despite its importance in cancer development, the Shh pathway has not been thoroughly investigated in tumorigenesis of brain tumors. In this study, we sought to understand the regulatory roles of GLI1, the immediate downstream activator of the Shh signaling pathway on its downstream target genes PTCH1, Cyclin D2, Plakoglobin, NKX2.2 and PAX6 in medulloblastoma and astrocytic tumors. We silenced GLI1 expression in medulloblastoma and astrocytic cell lines by transfection of siRNA against GLI1. Subsequently, we performed RT-PCR and quantitative real time RT-PCR (qRT-PCR) to assay the expression of downstream target genes PTCH1, Cyclin D2, Plakoglobin, NKX2.2 and PAX6. We also attempted to correlate the pattern of expression of GLI1 and its regulated genes in 14 cell lines and 41 primary medulloblastoma and astrocytoma tumor samples. We also assessed the methylation status of the Cyclin D2 and PTCH1 promoters in these 14 cell lines and 58 primary tumor samples. Silencing expression of GLI1 resulted up-regulation of all target genes in the medulloblastoma cell line, while only PTCH1 was up-regulated in astrocytoma. We also observed methylation of the cyclin D2 promoter in a significant number of astrocytoma cell lines (63%) and primary astrocytoma tumor samples (32%), but not at all in any medulloblastoma samples. PTCH1 promoter methylation was less frequently observed than Cyclin D2 promoter methylation in astrocytomas, and not at all in medulloblastomas. Our results demonstrate different regulatory mechanisms of Shh-GLI1 signaling. These differences vary according to the downstream target gene affected, the origin of the tissue, as well as epigenetic regulation of some of these genes

  4. A pediatric trial of radiation/cetuximab followed by irinotecan/cetuximab in newly diagnosed diffuse pontine gliomas and high-grade astrocytomas: A Pediatric Oncology Experimental Therapeutics Investigators' Consortium study.

    Science.gov (United States)

    Macy, Margaret E; Kieran, Mark W; Chi, Susan N; Cohen, Kenneth J; MacDonald, Tobey J; Smith, Amy A; Etzl, Michael M; Kuei, Michele C; Donson, Andrew M; Gore, Lia; DiRenzo, Jennifer; Trippett, Tanya M; Ostrovnaya, Irina; Narendran, Aru; Foreman, Nicholas K; Dunkel, Ira J

    2017-11-01

    Diffuse intrinsic pontine gliomas (DIPGs) and high-grade astrocytomas (HGA) continue to have dismal prognoses. The combination of cetuximab and irinotecan was demonstrated to be safe and tolerable in a previous pediatric phase 1 combination study. We developed this phase 2 trial to investigate the safety and efficacy of cetuximab given with radiation therapy followed by adjuvant cetuximab and irinotecan. Eligible patients of age 3-21 years had newly diagnosed DIPG or HGA. Patients received radiation therapy (5,940 cGy) with concurrent cetuximab. Following radiation, patients received cetuximab weekly and irinotecan daily for 5 days per week for 2 weeks every 21 days for 30 weeks. Correlative studies were performed. The regimen was considered to be promising if the number of patients with 1-year progression-free survival (PFS) for DIPG and HGA was at least six of 25 and 14 of 26, respectively. Forty-five evaluable patients were enrolled (25 DIPG and 20 HGA). Six patients with DIPG and five with HGA were progression free at 1 year from the start of therapy with 1-year PFS of 29.6% and 18%, respectively. Fatigue, gastrointestinal complaints, electrolyte abnormalities, and rash were the most common adverse events and generally of grade 1 and 2. Increased epidermal growth factor receptor copy number but no K-ras mutations were identified in available samples. The trial did not meet the predetermined endpoint to deem this regimen successful for HGA. While the trial met the predetermined endpoint for DIPG, overall survival was not markedly improved from historical controls, therefore does not merit further study in this population. © 2017 Wiley Periodicals, Inc.

  5. Robust loss functions for boosting.

    Science.gov (United States)

    Kanamori, Takafumi; Takenouchi, Takashi; Eguchi, Shinto; Murata, Noboru

    2007-08-01

    Boosting is known as a gradient descent algorithm over loss functions. It is often pointed out that the typical boosting algorithm, Adaboost, is highly affected by outliers. In this letter, loss functions for robust boosting are studied. Based on the concept of robust statistics, we propose a transformation of loss functions that makes boosting algorithms robust against extreme outliers. Next, the truncation of loss functions is applied to contamination models that describe the occurrence of mislabels near decision boundaries. Numerical experiments illustrate that the proposed loss functions derived from the contamination models are useful for handling highly noisy data in comparison with other loss functions.

  6. Theoretical Framework for Robustness Evaluation

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2011-01-01

    This paper presents a theoretical framework for evaluation of robustness of structural systems, incl. bridges and buildings. Typically modern structural design codes require that ‘the consequence of damages to structures should not be disproportional to the causes of the damages’. However, although...... the importance of robustness for structural design is widely recognized the code requirements are not specified in detail, which makes the practical use difficult. This paper describes a theoretical and risk based framework to form the basis for quantification of robustness and for pre-normative guidelines...

  7. Robustness of airline route networks

    Science.gov (United States)

    Lordan, Oriol; Sallan, Jose M.; Escorihuela, Nuria; Gonzalez-Prieto, David

    2016-03-01

    Airlines shape their route network by defining their routes through supply and demand considerations, paying little attention to network performance indicators, such as network robustness. However, the collapse of an airline network can produce high financial costs for the airline and all its geographical area of influence. The aim of this study is to analyze the topology and robustness of the network route of airlines following Low Cost Carriers (LCCs) and Full Service Carriers (FSCs) business models. Results show that FSC hubs are more central than LCC bases in their route network. As a result, LCC route networks are more robust than FSC networks.

  8. An Intercompany Perspective on Biopharmaceutical Drug Product Robustness Studies.

    Science.gov (United States)

    Morar-Mitrica, Sorina; Adams, Monica L; Crotts, George; Wurth, Christine; Ihnat, Peter M; Tabish, Tanvir; Antochshuk, Valentyn; DiLuzio, Willow; Dix, Daniel B; Fernandez, Jason E; Gupta, Kapil; Fleming, Michael S; He, Bing; Kranz, James K; Liu, Dingjiang; Narasimhan, Chakravarthy; Routhier, Eric; Taylor, Katherine D; Truong, Nobel; Stokes, Elaine S E

    2018-02-01

    The Biophorum Development Group (BPDG) is an industry-wide consortium enabling networking and sharing of best practices for the development of biopharmaceuticals. To gain a better understanding of current industry approaches for establishing biopharmaceutical drug product (DP) robustness, the BPDG-Formulation Point Share group conducted an intercompany collaboration exercise, which included a bench-marking survey and extensive group discussions around the scope, design, and execution of robustness studies. The results of this industry collaboration revealed several key common themes: (1) overall DP robustness is defined by both the formulation and the manufacturing process robustness; (2) robustness integrates the principles of quality by design (QbD); (3) DP robustness is an important factor in setting critical quality attribute control strategies and commercial specifications; (4) most companies employ robustness studies, along with prior knowledge, risk assessments, and statistics, to develop the DP design space; (5) studies are tailored to commercial development needs and the practices of each company. Three case studies further illustrate how a robustness study design for a biopharmaceutical DP balances experimental complexity, statistical power, scientific understanding, and risk assessment to provide the desired product and process knowledge. The BPDG-Formulation Point Share discusses identified industry challenges with regard to biopharmaceutical DP robustness and presents some recommendations for best practices. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  9. Exophytic pilocytic astrocytoma of the brain stem in an adult with encasement of the caudal cranial nerve complex (IX-XII): presurgical anatomical neuroimaging using MRI

    Energy Technology Data Exchange (ETDEWEB)

    Yousry, Indra; Yousry, Tarek A. [Department of Neuroradiology, Klinikum Grosshadern, Ludwig-Maximilians University, Marchioninistr. 15, 81377, Munich (Germany); Muacevic, Alexander; Olteanu-Nerbe, Vlad [Department of Neurosurgery, Klinikum Grosshadern, Ludwig-Maximilians University, Munich (Germany); Naidich, Thomas P. [Department of Radiology, Section of Neuroradiology, Mount Sinai Hospital, New York (United States)

    2004-07-01

    We describe a rare case of adult pilocytic astrocytoma in which exophytic growth from the brain stem presented as a right cerebellopontine angle mass. An initial MRI examination using T2- and T1-weighted images without and with contrast suggested the diagnosis of schwannoma. Subsequent use of 3D CISS (three-dimensional constructive interference in steady state) and T1-weighted contrast-enhanced 3D MP-RAGE (three-dimensional magnetization prepared rapid acquisition gradient echo) sequences led to the diagnosis of an exophytic brain stem tumor, documented the precise relationships of the tumor to cranial nerve VIII, revealed encasement of cranial nerves IX-XII (later confirmed intraoperatively), and provided the proper basis for planning surgical management. (orig.)

  10. Exophytic pilocytic astrocytoma of the brain stem in an adult with encasement of the caudal cranial nerve complex (IX-XII): presurgical anatomical neuroimaging using MRI

    International Nuclear Information System (INIS)

    Yousry, Indra; Yousry, Tarek A.; Muacevic, Alexander; Olteanu-Nerbe, Vlad; Naidich, Thomas P.

    2004-01-01

    We describe a rare case of adult pilocytic astrocytoma in which exophytic growth from the brain stem presented as a right cerebellopontine angle mass. An initial MRI examination using T2- and T1-weighted images without and with contrast suggested the diagnosis of schwannoma. Subsequent use of 3D CISS (three-dimensional constructive interference in steady state) and T1-weighted contrast-enhanced 3D MP-RAGE (three-dimensional magnetization prepared rapid acquisition gradient echo) sequences led to the diagnosis of an exophytic brain stem tumor, documented the precise relationships of the tumor to cranial nerve VIII, revealed encasement of cranial nerves IX-XII (later confirmed intraoperatively), and provided the proper basis for planning surgical management. (orig.)

  11. Robust Wave Resource Estimation

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    2013-01-01

    density estimates of the PDF as a function both of Hm0 and Tp, and Hm0 and T0;2, together with the mean wave power per unit crest length, Pw, as a function of Hm0 and T0;2. The wave elevation parameters, from which the wave parameters are calculated, are filtered to correct or remove spurious data....... An overview is given of the methods used to do this, and a method for identifying outliers of the wave elevation data, based on the joint distribution of wave elevations and accelerations, is presented. The limitations of using a JONSWAP spectrum to model the measured wave spectra as a function of Hm0 and T0......;2 or Hm0 and Tp for the Hanstholm site data are demonstrated. As an alternative, the non-parametric loess method, which does not rely on any assumptions about the shape of the wave elevation spectra, is used to accurately estimate Pw as a function of Hm0 and T0;2....

  12. Robust Portfolio Optimization Using Pseudodistances.

    Science.gov (United States)

    Toma, Aida; Leoni-Aubin, Samuela

    2015-01-01

    The presence of outliers in financial asset returns is a frequently occurring phenomenon which may lead to unreliable mean-variance optimized portfolios. This fact is due to the unbounded influence that outliers can have on the mean returns and covariance estimators that are inputs in the optimization procedure. In this paper we present robust estimators of mean and covariance matrix obtained by minimizing an empirical version of a pseudodistance between the assumed model and the true model underlying the data. We prove and discuss theoretical properties of these estimators, such as affine equivariance, B-robustness, asymptotic normality and asymptotic relative efficiency. These estimators can be easily used in place of the classical estimators, thereby providing robust optimized portfolios. A Monte Carlo simulation study and applications to real data show the advantages of the proposed approach. We study both in-sample and out-of-sample performance of the proposed robust portfolios comparing them with some other portfolios known in literature.

  13. Radiotherapy in pediatric pilocytic astrocytomas. A subgroup analysis within the prospective multicenter study HIT-LGG 1996 by the German Society of Pediatric Oncology and Hematology (GPOH)

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, K. [Leipzig Univ. (Germany). Dept. of Radiotherapy and Radiation Oncology; Gnekow, A.; Falkenstein, F. [General Hospital of Augsburg (Germany). Hospital for Children and Adolescents] [and others

    2013-08-15

    Purpose: We evaluated clinical outcomes in the subset of patients who underwent radiotherapy (RT) due to progressive pilocytic astrocytoma within the Multicenter Treatment Study for Children and Adolescents with a Low Grade Glioma HIT-LGG 1996. Patients and methods: Eligibility criteria were fulfilled by 117 patients. Most tumors (65 %) were located in the supratentorial midline, followed by the posterior fossa (26.5 %) and the cerebral hemispheres (8.5 %). Median age at the start of RT was 9.2 years (range 0.7-17.4 years). In 75 cases, external fractionated radiotherapy (EFRT) was administered either as first-line nonsurgical treatment (n = 58) or after progression following primary chemotherapy (n = 17). The median normalized total dose was 54 Gy. Stereotactic brachytherapy (SBT) was used in 42 selected cases. Results: During a median follow-up period of 8.4 years, 4 patients (3.4 %) died and 33 (27.4 %) experienced disease progression. The 10-year overall (OS) and progression-free survival (PFS) rates were 97 and 70 %, respectively. No impact of the RT technique applied (EFRT versus SBT) on progression was observed. The 5-year PFS was 76 {+-} 5 % after EFRT and 65 {+-} 8 % after SBT. Disease progression after EFRT was not influenced by gender, neurofibromatosis type 1 (NF1) status, tumor location (hemispheres versus supratentorial midline versus posterior fossa), age or prior chemotherapy. Normalized total EFRT doses of more than 50.4 Gy did not improve PFS rates. Conclusion: EFRT plays an integral role in the treatment of pediatric pilocytic astrocytoma and is characterized by excellent tumor control. A reduction of the normalized total dose from 54 to 50.4 Gy appears to be feasible without jeopardizing tumor control. SBT is an effective treatment alternative. (orig.)

  14. Prognostic factors and survival in primary malignant astrocytomas of the spinal cord: a population-based analysis from 1973 to 2007.

    Science.gov (United States)

    Adams, Hadie; Avendaño, Javier; Raza, Shaan M; Gokaslan, Ziya L; Jallo, George I; Quiñones-Hinojosa, Alfredo

    2012-05-20

    Observational cross-sectional study. Using data from the population-based cancer registries of the Surveillance, Epidemiology and End Results (SEER) program, we analyzed demographic features, tumor and treatment characteristics, as well as survival rates in patients with primary malignant astrocytomas of the spinal cord (PMASC). PMASC is a rare neoplasm and is considered to carry the same dismal outcome as their cerebral counterparts. Our current knowledge is incomplete, and understanding the epidemiology, diagnosis, and optimal treatment still poses challenges. The SEER data from 1973 to 2007 were reviewed for pathologically confirmed primary anaplastic astrocytomas (AA) and glioblastomas of the spinal cord (C72.0). We compared the clinical features and outcomes of the cohort in uni- and multivariate fashion. Survival was calculated and compared using Kaplan-Meier curves and log-rank analysis. Our search criteria retrieved 135 patients diagnosed with PMASC. The median survival for PMASC was 13 months with 1-, 2-, and 5-year survival rates of 51.8%, 32.2%, and 18.7%. Patient diagnosed with AA had a median survival time of 17 months versus 10 months in patients diagnosed with glioblastomas. Adult patients observed markedly prolonged survival compared with the pediatric group, with a 16-month versus 9-month median survival, respectively. Multivariate analysis revealed age at diagnosis, pediatric and adult age groups, sex, tumor histology, and extent of resection as significant predictors of survival. Interestingly, outcomes did not significantly change throughout the last decades or by receiving radiotherapy. Outcome for patients diagnosed with PMASC remains poor and presents an ongoing challenge for professionals in the field of neurospinal medicine and surgery. In our analyses of AA, adult patients, males, and patients undergoing radical resections were associated with increased survival. However, incidence of these lesions is low; hence, building strong

  15. Guanine nucleotide-dependent, pertussis toxin-insensitive, stimulation of inositol phosphate formation by carbachol in a membrane preparation from astrocytoma cells

    International Nuclear Information System (INIS)

    Hepler, J.R.; Harden, T.K.

    1986-01-01

    Formation of the inositol phosphates (InsP), InsP 3 , InsP 2 , and InsP 1 was increased in a concentration dependent manner (K/sub 0.5/ ∼ 5 μM) by GTPΣS in washed membranes prepared from 3 H-inositol-prelabelled 1321N1 human astrocytoma cells. Both GTPγS and GppNHp stimulated InsP formation by 2-3 fold over control; GTP and GDP were much less efficacious and GMP had no effect. Although the muscarinic cholinergic receptor agonist carbachol had no effect in the absence of guanine nucleotide, in the presence of 10 μM GTPγS, carbachol stimulated (K/sub 0.5/ ∼ 10 μ M) the formation of InsP above the level achieved with GTPγS alone. The effect of carbachol was completely blocked by atropine. The order of potency for a series of nucleotides for stimulation of InsP formation in the presence of 500 μM carbachol was GTPγS > GppNHp > GTP = GDP. Pertussis toxin, at concentrations that fully ADP-ribosylate and functionally inactivate G/sub i/, had no effect on InsP formation in the presence of GTPγS or GTPγS plus carbachol. Histamine and bradykinin also stimulated InsP formation in the presence of GTPγS in washed membranes from 1321N1 cells. These data are consistent with the idea that a guanine nucleotide regulatory protein that is not G/sub i/ is involved in receptor-mediated stimulation of InsP formation in 1321N1 human astrocytoma cells

  16. Robust methods for data reduction

    CERN Document Server

    Farcomeni, Alessio

    2015-01-01

    Robust Methods for Data Reduction gives a non-technical overview of robust data reduction techniques, encouraging the use of these important and useful methods in practical applications. The main areas covered include principal components analysis, sparse principal component analysis, canonical correlation analysis, factor analysis, clustering, double clustering, and discriminant analysis.The first part of the book illustrates how dimension reduction techniques synthesize available information by reducing the dimensionality of the data. The second part focuses on cluster and discriminant analy

  17. Robust Design Impact Metrics: Measuring the effect of implementing and using Robust Design

    DEFF Research Database (Denmark)

    Ebro, Martin; Olesen, Jesper; Howard, Thomas J.

    2014-01-01

    Measuring the performance of an organisation’s product development process can be challenging due to the limited use of metrics in R&D. An organisation considering whether to use Robust Design as an integrated part of their development process may find it difficult to define whether it is relevant......, and afterwards measure the effect of having implemented it. This publication identifies and evaluates Robust Design-related metrics and finds that 2 metrics are especially useful: 1) Relative amount of R&D Resources spent after Design Verification and 2) Number of ‘change notes’ after Design Verification....... The metrics have been applied in a case company to test the assumptions made during the evaluation. It is concluded that the metrics are useful and relevant, but further work is necessary to make a proper overview and categorisation of different types of robustness related metrics....

  18. The effectiveness of robust RMCD control chart as outliers’ detector

    Science.gov (United States)

    Darmanto; Astutik, Suci

    2017-12-01

    A well-known control chart to monitor a multivariate process is Hotelling’s T 2 which its parameters are estimated classically, very sensitive and also marred by masking and swamping of outliers data effect. To overcome these situation, robust estimators are strongly recommended. One of robust estimators is re-weighted minimum covariance determinant (RMCD) which has robust characteristics as same as MCD. In this paper, the effectiveness term is accuracy of the RMCD control chart in detecting outliers as real outliers. In other word, how effectively this control chart can identify and remove masking and swamping effects of outliers. We assessed the effectiveness the robust control chart based on simulation by considering different scenarios: n sample sizes, proportion of outliers, number of p quality characteristics. We found that in some scenarios, this RMCD robust control chart works effectively.

  19. Robust design optimization using the price of robustness, robust least squares and regularization methods

    Science.gov (United States)

    Bukhari, Hassan J.

    2017-12-01

    In this paper a framework for robust optimization of mechanical design problems and process systems that have parametric uncertainty is presented using three different approaches. Robust optimization problems are formulated so that the optimal solution is robust which means it is minimally sensitive to any perturbations in parameters. The first method uses the price of robustness approach which assumes the uncertain parameters to be symmetric and bounded. The robustness for the design can be controlled by limiting the parameters that can perturb.The second method uses the robust least squares method to determine the optimal parameters when data itself is subjected to perturbations instead of the parameters. The last method manages uncertainty by restricting the perturbation on parameters to improve sensitivity similar to Tikhonov regularization. The methods are implemented on two sets of problems; one linear and the other non-linear. This methodology will be compared with a prior method using multiple Monte Carlo simulation runs which shows that the approach being presented in this paper results in better performance.

  20. Advances in robust fractional control

    CERN Document Server

    Padula, Fabrizio

    2015-01-01

    This monograph presents design methodologies for (robust) fractional control systems. It shows the reader how to take advantage of the superior flexibility of fractional control systems compared with integer-order systems in achieving more challenging control requirements. There is a high degree of current interest in fractional systems and fractional control arising from both academia and industry and readers from both milieux are catered to in the text. Different design approaches having in common a trade-off between robustness and performance of the control system are considered explicitly. The text generalizes methodologies, techniques and theoretical results that have been successfully applied in classical (integer) control to the fractional case. The first part of Advances in Robust Fractional Control is the more industrially-oriented. It focuses on the design of fractional controllers for integer processes. In particular, it considers fractional-order proportional-integral-derivative controllers, becau...

  1. Robustness of digital artist authentication

    DEFF Research Database (Denmark)

    Jacobsen, Robert; Nielsen, Morten

    In many cases it is possible to determine the authenticity of a painting from digital reproductions of the paintings; this has been demonstrated for a variety of artists and with different approaches. Common to all these methods in digital artist authentication is that the potential of the method...... is in focus, while the robustness has not been considered, i.e. the degree to which the data collection process influences the decision of the method. However, in order for an authentication method to be successful in practice, it needs to be robust to plausible error sources from the data collection....... In this paper we investigate the robustness of the newly proposed authenticity method introduced by the authors based on second generation multiresolution analysis. This is done by modelling a number of realistic factors that can occur in the data collection....

  2. Attractive ellipsoids in robust control

    CERN Document Server

    Poznyak, Alexander; Azhmyakov, Vadim

    2014-01-01

    This monograph introduces a newly developed robust-control design technique for a wide class of continuous-time dynamical systems called the “attractive ellipsoid method.” Along with a coherent introduction to the proposed control design and related topics, the monograph studies nonlinear affine control systems in the presence of uncertainty and presents a constructive and easily implementable control strategy that guarantees certain stability properties. The authors discuss linear-style feedback control synthesis in the context of the above-mentioned systems. The development and physical implementation of high-performance robust-feedback controllers that work in the absence of complete information is addressed, with numerous examples to illustrate how to apply the attractive ellipsoid method to mechanical and electromechanical systems. While theorems are proved systematically, the emphasis is on understanding and applying the theory to real-world situations. Attractive Ellipsoids in Robust Control will a...

  3. Robustness of holonomic quantum gates

    International Nuclear Information System (INIS)

    Solinas, P.; Zanardi, P.; Zanghi, N.

    2005-01-01

    Full text: If the driving field fluctuates during the quantum evolution this produces errors in the applied operator. The holonomic (and geometrical) quantum gates are believed to be robust against some kind of noise. Because of the geometrical dependence of the holonomic operators can be robust against this kind of noise; in fact if the fluctuations are fast enough they cancel out leaving the final operator unchanged. I present the numerical studies of holonomic quantum gates subject to this parametric noise, the fidelity of the noise and ideal evolution is calculated for different noise correlation times. The holonomic quantum gates seem robust not only for fast fluctuating fields but also for slow fluctuating fields. These results can be explained as due to the geometrical feature of the holonomic operator: for fast fluctuating fields the fluctuations are canceled out, for slow fluctuating fields the fluctuations do not perturb the loop in the parameter space. (author)

  4. Robust estimation and hypothesis testing

    CERN Document Server

    Tiku, Moti L

    2004-01-01

    In statistical theory and practice, a certain distribution is usually assumed and then optimal solutions sought. Since deviations from an assumed distribution are very common, one cannot feel comfortable with assuming a particular distribution and believing it to be exactly correct. That brings the robustness issue in focus. In this book, we have given statistical procedures which are robust to plausible deviations from an assumed mode. The method of modified maximum likelihood estimation is used in formulating these procedures. The modified maximum likelihood estimators are explicit functions of sample observations and are easy to compute. They are asymptotically fully efficient and are as efficient as the maximum likelihood estimators for small sample sizes. The maximum likelihood estimators have computational problems and are, therefore, elusive. A broad range of topics are covered in this book. Solutions are given which are easy to implement and are efficient. The solutions are also robust to data anomali...

  5. Robustness in Railway Operations (RobustRailS)

    DEFF Research Database (Denmark)

    Jensen, Jens Parbo; Nielsen, Otto Anker

    This study considers the problem of enhancing railway timetable robustness without adding slack time, hence increasing the travel time. The approach integrates a transit assignment model to assess how passengers adapt their behaviour whenever operations are changed. First, the approach considers...

  6. Effect of robust torus on the dynamical transport

    International Nuclear Information System (INIS)

    Martins, C G L; Carvalho, R Egydio de; Caldas, I L; Roberto, M

    2010-01-01

    In the present work, we quantify the fraction of trajectories that reach a specific region of the phase space when we vary a control parameter using two symplectic maps: one non-twist and another one twist. The two maps were studied with and without a robust torus. We compare the obtained patterns and we identify the effect of the robust torus on the dynamical transport. We show that the effect of meandering-like barriers loses importance in blocking the radial transport when the robust torus is present.

  7. Robustness of the ATLAS pixel clustering neural network algorithm

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00407780; The ATLAS collaboration

    2016-01-01

    Proton-proton collisions at the energy frontier puts strong constraints on track reconstruction algorithms. In the ATLAS track reconstruction algorithm, an artificial neural network is utilised to identify and split clusters of neighbouring read-out elements in the ATLAS pixel detector created by multiple charged particles. The robustness of the neural network algorithm is presented, probing its sensitivity to uncertainties in the detector conditions. The robustness is studied by evaluating the stability of the algorithm's performance under a range of variations in the inputs to the neural networks. Within reasonable variation magnitudes, the neural networks prove to be robust to most variation types.

  8. A Robust Design Applicability Model

    DEFF Research Database (Denmark)

    Ebro, Martin; Lars, Krogstie; Howard, Thomas J.

    2015-01-01

    to be applicable in organisations assigning a high importance to one or more factors that are known to be impacted by RD, while also experiencing a high level of occurrence of this factor. The RDAM supplements existing maturity models and metrics to provide a comprehensive set of data to support management......This paper introduces a model for assessing the applicability of Robust Design (RD) in a project or organisation. The intention of the Robust Design Applicability Model (RDAM) is to provide support for decisions by engineering management considering the relevant level of RD activities...

  9. Ins-Robust Primitive Words

    OpenAIRE

    Srivastava, Amit Kumar; Kapoor, Kalpesh

    2017-01-01

    Let Q be the set of primitive words over a finite alphabet with at least two symbols. We characterize a class of primitive words, Q_I, referred to as ins-robust primitive words, which remain primitive on insertion of any letter from the alphabet and present some properties that characterizes words in the set Q_I. It is shown that the language Q_I is dense. We prove that the language of primitive words that are not ins-robust is not context-free. We also present a linear time algorithm to reco...

  10. A robust human face detection algorithm

    Science.gov (United States)

    Raviteja, Thaluru; Karanam, Srikrishna; Yeduguru, Dinesh Reddy V.

    2012-01-01

    Human face detection plays a vital role in many applications like video surveillance, managing a face image database, human computer interface among others. This paper proposes a robust algorithm for face detection in still color images that works well even in a crowded environment. The algorithm uses conjunction of skin color histogram, morphological processing and geometrical analysis for detecting human faces. To reinforce the accuracy of face detection, we further identify mouth and eye regions to establish the presence/absence of face in a particular region of interest.

  11. Robust indexing for automatic data collection

    International Nuclear Information System (INIS)

    Sauter, Nicholas K.; Grosse-Kunstleve, Ralf W.; Adams, Paul D.

    2003-01-01

    We present improved methods for indexing diffraction patterns from macromolecular crystals. The novel procedures include a more robust way to verify the position of the incident X-ray beam on the detector, an algorithm to verify that the deduced lattice basis is consistent with the observations, and an alternative approach to identify the metric symmetry of the lattice. These methods help to correct failures commonly experienced during indexing, and increase the overall success rate of the process. Rapid indexing, without the need for visual inspection, will play an important role as beamlines at synchrotron sources prepare for high-throughput automation

  12. Essays on robust asset pricing

    NARCIS (Netherlands)

    Horváth, Ferenc

    2017-01-01

    The central concept of this doctoral dissertation is robustness. I analyze how model and parameter uncertainty affect financial decisions of investors and fund managers, and what their equilibrium consequences are. Chapter 1 gives an overview of the most important concepts and methodologies used in

  13. Robust visual hashing via ICA

    International Nuclear Information System (INIS)

    Fournel, Thierry; Coltuc, Daniela

    2010-01-01

    Designed to maximize information transmission in the presence of noise, independent component analysis (ICA) could appear in certain circumstances as a statistics-based tool for robust visual hashing. Several ICA-based scenarios can attempt to reach this goal. A first one is here considered.

  14. Robustness of raw quantum tomography

    Science.gov (United States)

    Asorey, M.; Facchi, P.; Florio, G.; Man'ko, V. I.; Marmo, G.; Pascazio, S.; Sudarshan, E. C. G.

    2011-01-01

    We scrutinize the effects of non-ideal data acquisition on the tomograms of quantum states. The presence of a weight function, schematizing the effects of a finite window or equivalently noise, only affects the state reconstruction procedure by a normalization constant. The results are extended to a discrete mesh and show that quantum tomography is robust under incomplete and approximate knowledge of tomograms.

  15. Robustness of raw quantum tomography

    Energy Technology Data Exchange (ETDEWEB)

    Asorey, M. [Departamento de Fisica Teorica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza (Spain); Facchi, P. [Dipartimento di Matematica, Universita di Bari, I-70125 Bari (Italy); INFN, Sezione di Bari, I-70126 Bari (Italy); MECENAS, Universita Federico II di Napoli and Universita di Bari (Italy); Florio, G. [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); INFN, Sezione di Bari, I-70126 Bari (Italy); MECENAS, Universita Federico II di Napoli and Universita di Bari (Italy); Man' ko, V.I., E-mail: manko@lebedev.r [P.N. Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991 (Russian Federation); Marmo, G. [Dipartimento di Scienze Fisiche, Universita di Napoli ' Federico II' , I-80126 Napoli (Italy); INFN, Sezione di Napoli, I-80126 Napoli (Italy); MECENAS, Universita Federico II di Napoli and Universita di Bari (Italy); Pascazio, S. [Dipartimento di Fisica, Universita di Bari, I-70126 Bari (Italy); INFN, Sezione di Bari, I-70126 Bari (Italy); MECENAS, Universita Federico II di Napoli and Universita di Bari (Italy); Sudarshan, E.C.G. [Department of Physics, University of Texas, Austin, TX 78712 (United States)

    2011-01-31

    We scrutinize the effects of non-ideal data acquisition on the tomograms of quantum states. The presence of a weight function, schematizing the effects of a finite window or equivalently noise, only affects the state reconstruction procedure by a normalization constant. The results are extended to a discrete mesh and show that quantum tomography is robust under incomplete and approximate knowledge of tomograms.

  16. Aspects of robust linear regression

    NARCIS (Netherlands)

    Davies, P.L.

    1993-01-01

    Section 1 of the paper contains a general discussion of robustness. In Section 2 the influence function of the Hampel-Rousseeuw least median of squares estimator is derived. Linearly invariant weak metrics are constructed in Section 3. It is shown in Section 4 that $S$-estimators satisfy an exact

  17. Manipulation Robustness of Collaborative Filtering

    OpenAIRE

    Benjamin Van Roy; Xiang Yan

    2010-01-01

    A collaborative filtering system recommends to users products that similar users like. Collaborative filtering systems influence purchase decisions and hence have become targets of manipulation by unscrupulous vendors. We demonstrate that nearest neighbors algorithms, which are widely used in commercial systems, are highly susceptible to manipulation and introduce new collaborative filtering algorithms that are relatively robust.

  18. Robustness Regions for Dichotomous Decisions.

    Science.gov (United States)

    Vijn, Pieter; Molenaar, Ivo W.

    1981-01-01

    In the case of dichotomous decisions, the total set of all assumptions/specifications for which the decision would have been the same is the robustness region. Inspection of this (data-dependent) region is a form of sensitivity analysis which may lead to improved decision making. (Author/BW)

  19. Theoretical Framework for Robustness Evaluation

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2011-01-01

    This paper presents a theoretical framework for evaluation of robustness of structural systems, incl. bridges and buildings. Typically modern structural design codes require that ‘the consequence of damages to structures should not be disproportional to the causes of the damages’. However, althou...

  20. Robust control design with MATLAB

    CERN Document Server

    Gu, Da-Wei; Konstantinov, Mihail M

    2013-01-01

    Robust Control Design with MATLAB® (second edition) helps the student to learn how to use well-developed advanced robust control design methods in practical cases. To this end, several realistic control design examples from teaching-laboratory experiments, such as a two-wheeled, self-balancing robot, to complex systems like a flexible-link manipulator are given detailed presentation. All of these exercises are conducted using MATLAB® Robust Control Toolbox 3, Control System Toolbox and Simulink®. By sharing their experiences in industrial cases with minimum recourse to complicated theories and formulae, the authors convey essential ideas and useful insights into robust industrial control systems design using major H-infinity optimization and related methods allowing readers quickly to move on with their own challenges. The hands-on tutorial style of this text rests on an abundance of examples and features for the second edition: ·        rewritten and simplified presentation of theoretical and meth...

  1. Robust Portfolio Optimization Using Pseudodistances

    Science.gov (United States)

    2015-01-01

    The presence of outliers in financial asset returns is a frequently occurring phenomenon which may lead to unreliable mean-variance optimized portfolios. This fact is due to the unbounded influence that outliers can have on the mean returns and covariance estimators that are inputs in the optimization procedure. In this paper we present robust estimators of mean and covariance matrix obtained by minimizing an empirical version of a pseudodistance between the assumed model and the true model underlying the data. We prove and discuss theoretical properties of these estimators, such as affine equivariance, B-robustness, asymptotic normality and asymptotic relative efficiency. These estimators can be easily used in place of the classical estimators, thereby providing robust optimized portfolios. A Monte Carlo simulation study and applications to real data show the advantages of the proposed approach. We study both in-sample and out-of-sample performance of the proposed robust portfolios comparing them with some other portfolios known in literature. PMID:26468948

  2. Facial Symmetry in Robust Anthropometrics

    Czech Academy of Sciences Publication Activity Database

    Kalina, Jan

    2012-01-01

    Roč. 57, č. 3 (2012), s. 691-698 ISSN 0022-1198 R&D Projects: GA MŠk(CZ) 1M06014 Institutional research plan: CEZ:AV0Z10300504 Keywords : forensic science * anthropology * robust image analysis * correlation analysis * multivariate data * classification Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.244, year: 2012

  3. Sparse and Robust Factor Modelling

    NARCIS (Netherlands)

    C. Croux (Christophe); P. Exterkate (Peter)

    2011-01-01

    textabstractFactor construction methods are widely used to summarize a large panel of variables by means of a relatively small number of representative factors. We propose a novel factor construction procedure that enjoys the properties of robustness to outliers and of sparsity; that is, having

  4. Robust distributed cognitive relay beamforming

    KAUST Repository

    Pandarakkottilil, Ubaidulla; Aissa, Sonia

    2012-01-01

    design takes into account a parameter of the error in the channel state information (CSI) to render the performance of the beamformer robust in the presence of imperfect CSI. Though the original problem is non-convex, we show that the proposed design can

  5. Approximability of Robust Network Design

    NARCIS (Netherlands)

    Olver, N.K.; Shepherd, F.B.

    2014-01-01

    We consider robust (undirected) network design (RND) problems where the set of feasible demands may be given by an arbitrary convex body. This model, introduced by Ben-Ameur and Kerivin [Ben-Ameur W, Kerivin H (2003) New economical virtual private networks. Comm. ACM 46(6):69-73], generalizes the

  6. Robust Reliability or reliable robustness? - Integrated consideration of robustness and reliability aspects

    DEFF Research Database (Denmark)

    Kemmler, S.; Eifler, Tobias; Bertsche, B.

    2015-01-01

    products are and vice versa. For a comprehensive understanding and to use existing synergies between both domains, this paper discusses the basic principles of Reliability- and Robust Design theory. The development of a comprehensive model will enable an integrated consideration of both domains...

  7. Robust Watermarking of Video Streams

    Directory of Open Access Journals (Sweden)

    T. Polyák

    2006-01-01

    Full Text Available In the past few years there has been an explosion in the use of digital video data. Many people have personal computers at home, and with the help of the Internet users can easily share video files on their computer. This makes possible the unauthorized use of digital media, and without adequate protection systems the authors and distributors have no means to prevent it.Digital watermarking techniques can help these systems to be more effective by embedding secret data right into the video stream. This makes minor changes in the frames of the video, but these changes are almost imperceptible to the human visual system. The embedded information can involve copyright data, access control etc. A robust watermark is resistant to various distortions of the video, so it cannot be removed without affecting the quality of the host medium. In this paper I propose a video watermarking scheme that fulfills the requirements of a robust watermark. 

  8. Robust Decentralized Formation Flight Control

    Directory of Open Access Journals (Sweden)

    Zhao Weihua

    2011-01-01

    Full Text Available Motivated by the idea of multiplexed model predictive control (MMPC, this paper introduces a new framework for unmanned aerial vehicles (UAVs formation flight and coordination. Formulated using MMPC approach, the whole centralized formation flight system is considered as a linear periodic system with control inputs of each UAV subsystem as its periodic inputs. Divided into decentralized subsystems, the whole formation flight system is guaranteed stable if proper terminal cost and terminal constraints are added to each decentralized MPC formulation of the UAV subsystem. The decentralized robust MPC formulation for each UAV subsystem with bounded input disturbances and model uncertainties is also presented. Furthermore, an obstacle avoidance control scheme for any shape and size of obstacles, including the nonapriorily known ones, is integrated under the unified MPC framework. The results from simulations demonstrate that the proposed framework can successfully achieve robust collision-free formation flights.

  9. Salmon: Robust Proxy Distribution for Censorship Circumvention

    Directory of Open Access Journals (Sweden)

    Douglas Frederick

    2016-10-01

    Full Text Available Many governments block their citizens’ access to much of the Internet. Simple workarounds are unreliable; censors quickly discover and patch them. Previously proposed robust approaches either have non-trivial obstacles to deployment, or rely on low-performance covert channels that cannot support typical Internet usage such as streaming video. We present Salmon, an incrementally deployable system designed to resist a censor with the resources of the “Great Firewall” of China. Salmon relies on a network of volunteers in uncensored countries to run proxy servers. Although any member of the public can become a user, Salmon protects the bulk of its servers from being discovered and blocked by the censor via an algorithm for quickly identifying malicious users. The algorithm entails identifying some users as especially trustworthy or suspicious, based on their actions. We impede Sybil attacks by requiring either an unobtrusive check of a social network account, or a referral from a trustworthy user.

  10. Inefficient but robust public leadership.

    OpenAIRE

    Matsumura, Toshihiro; Ogawa, Akira

    2014-01-01

    We investigate endogenous timing in a mixed duopoly in a differentiated product market. We find that private leadership is better than public leadership from a social welfare perspective if the private firm is domestic, regardless of the degree of product differentiation. Nevertheless, the public leadership equilibrium is risk-dominant, and it is thus robust if the degree of product differentiation is high. We also find that regardless of the degree of product differentiation, the public lead...

  11. Testing Heteroscedasticity in Robust Regression

    Czech Academy of Sciences Publication Activity Database

    Kalina, Jan

    2011-01-01

    Roč. 1, č. 4 (2011), s. 25-28 ISSN 2045-3345 Grant - others:GA ČR(CZ) GA402/09/0557 Institutional research plan: CEZ:AV0Z10300504 Keywords : robust regression * heteroscedasticity * regression quantiles * diagnostics Subject RIV: BB - Applied Statistics , Operational Research http://www.researchjournals.co.uk/documents/Vol4/06%20Kalina.pdf

  12. Robust power system frequency control

    CERN Document Server

    Bevrani, Hassan

    2014-01-01

    This updated edition of the industry standard reference on power system frequency control provides practical, systematic and flexible algorithms for regulating load frequency, offering new solutions to the technical challenges introduced by the escalating role of distributed generation and renewable energy sources in smart electric grids. The author emphasizes the physical constraints and practical engineering issues related to frequency in a deregulated environment, while fostering a conceptual understanding of frequency regulation and robust control techniques. The resulting control strategi

  13. Constitutional chromosomal events at 22q11 and 15q26 in a child with a pilocytic astrocytoma of the spinal cord.

    Science.gov (United States)

    Mascelli, Samantha; Severino, Mariasavina; Raso, Alessandro; Nozza, Paolo; Tassano, Elisa; Morana, Giovanni; De Marco, Patrizia; Merello, Elisa; Milanaccio, Claudia; Pavanello, Marco; Rossi, Andrea; Cama, Armando; Garrè, Maria Luisa; Capra, Valeria

    2014-01-01

    We report on a 9-years-old patient with mild intellectual disability, facial dimorphisms, bilateral semicircular canal dysplasia, periventricular nodular heterotopias, bilateral hippocampal malrotation and abnormal cerebellar foliation, who developed mild motor impairment and gait disorder due to a pilocytic astrocytoma of the spinal cord. Array-CGH analysis revealed two paternal inherited chromosomal events: a 484.3 Kb duplication on chromosome 15q26.3 and a 247 Kb deletion on 22q11.23. Further, a second de novo 1.5 Mb deletion on 22q11.21 occurred. Chromosome 22 at q11.2 and chromosome 15 at q24q26 are considered unstable regions subjected to copy number variations, i.e. structural alterations of genome, mediated by low copy repeat sequences or segmental duplications. The link between some structural CNVs, which compromise fundamental processes controlling DNA stability, and genomic disorders suggest a plausible scenario for cancer predisposition. Evaluation of the genes at the breakpoints cannot account simultaneously for the phenotype and tumour development in this patient. The two paternal inherited CNVs arguably are not pathogenic and do not contribute to the clinical manifestations. Similarly, although the de novo large deletion at 22q11.21 overlaps with the Di George (DGS) critical region and results in haploinsufficiency of genes compromising critical processes for DNA stability, this case lacks several hallmarks of DGS.

  14. Adult Diffuse Astrocytoma in the Medulla Oblongata: Molecular Biological Analyses Including H3F3A Mutation of Histone H3.3.

    Science.gov (United States)

    Uekawa, Ken; Nakamura, Hideo; Shinojima, Naoki; Takezaki, Tatsuya; Yano, Shigetoshi; Kuratsu, Jun-Ichi

    2016-04-01

    Unlike in children, brain stem gliomas in adult are rare and still poorly understood. In addition, most adult brain stem gliomas result predominantly in the pons and are less often found in the medulla oblongata. Here, we report a case of an adult glioma in the medulla oblongata and its molecular biological features. A 46-year-old male presented with gait disturbance, paresthesia, and dysphagia. Magnetic resonance imaging (MRI) showed a diffuse hyper-intensive lesion in the medulla oblongata on a T 2 -weighted image without gadolinium contrast enhancement. We performed an open biopsy and the lesion was pathologically diagnosed as a diffuse astrocytoma. Molecular biological analyses revealed the absence of histone H3.3 mutation (H3F3A K27M), and presence of methylation of O-6-methylguanine-DNA methyltransferase (MGMT) promoter and a mutation in isocitrate dehydrogenase 1 (IDH-1). The patient received local radiotherapy and temozolomide chemotherapy. The patient's symptoms were ameliorated, and MRI showed no tumor growth at 6 months after the initial treatment. Biopsy for brain stem lesions is generally thought to have risk of complications, but if performed minimally, it is useful to diagnose and determine treatment strategy. Obtaining patient characteristics and molecular biological features will provide insight towards therapeutic treatment for adult brain stem gliomas.

  15. AUTOCOUNTER, an ImageJ JavaScript to analyze LC3B-GFP expression dynamics in autophagy-induced astrocytoma cells.

    Science.gov (United States)

    Fassina, L; Magenes, G; Inzaghi, A; Palumbo, S; Allavena, G; Miracco, C; Pirtoli, L; Biggiogera, M; Comincini, S

    2012-10-11

    An ImageJ JavaScript, AUTOCOUNTER, was specifically developed to monitor and measure LC3B-GFP expression in living human astrocytoma cells, namely T98G and U373-MG. Discrete intracellular GFP fluorescent spots derived from transduction of a Baculovirus replication-defective vector (BacMam LC3B-GFP), followed by microscope examinations at different times. After viral transgene expression, autophagy was induced by Rapamycin administration and assayed in ph-p70S6K/p70S6K and LC3B immunoblotting expression as well as by electron microscopy examinations. A mutated transgene, defective in LC3B lipidation, was employed as a negative control to further exclude fluorescent dots derived from protein intracellular aggregation. The ImageJ JavaScript was then employed to evaluate and score the dynamics changes of the number and area of LC3B-GFP puncta per cell in time course assays and in complex microscope examinations. In conclusion, AUTOCOUNTER enabled to quantify LC3B-GFP expression and to monitor dynamics changes in number and shapes of autophagosomal-like vesicles: it might therefore represent a suitable algorithmic tool for in vitro autophagy modulation studies.

  16. Robustness Analysis of Timber Truss Structure

    DEFF Research Database (Denmark)

    Rajčić, Vlatka; Čizmar, Dean; Kirkegaard, Poul Henning

    2010-01-01

    The present paper discusses robustness of structures in general and the robustness requirements given in the codes. Robustness of timber structures is also an issues as this is closely related to Working group 3 (Robustness of systems) of the COST E55 project. Finally, an example of a robustness...... evaluation of a widespan timber truss structure is presented. This structure was built few years ago near Zagreb and has a span of 45m. Reliability analysis of the main members and the system is conducted and based on this a robustness analysis is preformed....

  17. Soliton robustness in optical fibers

    International Nuclear Information System (INIS)

    Menyuk, C.R.

    1993-01-01

    Simulations and experiments indicate that solitons in optical fibers are robust in the presence of Hamiltonian deformations such as higher-order dispersion and birefringence but are destroyed in the presence of non-Hamiltonian deformations such as attenuation and the Raman effect. Two hypotheses are introduced that generalize these observations and give a recipe for when deformations will be Hamiltonian. Concepts from nonlinear dynamics are used to make these two hypotheses plausible. Soliton stabilization with frequency filtering is also briefly discussed from this point of view

  18. Robust and Sparse Factor Modelling

    DEFF Research Database (Denmark)

    Croux, Christophe; Exterkate, Peter

    Factor construction methods are widely used to summarize a large panel of variables by means of a relatively small number of representative factors. We propose a novel factor construction procedure that enjoys the properties of robustness to outliers and of sparsity; that is, having relatively few...... nonzero factor loadings. Compared to the traditional factor construction method, we find that this procedure leads to a favorable forecasting performance in the presence of outliers and to better interpretable factors. We investigate the performance of the method in a Monte Carlo experiment...

  19. Robustness Evaluation of Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; čizmar, D.

    2010-01-01

    The present paper outlines results from working group 3 (WG3) in the EU COST Action E55 – ‘Modelling of the performance of timber structures’. The objectives of the project are related to the three main research activities: the identification and modelling of relevant load and environmental...... exposure scenarios, the improvement of knowledge concerning the behaviour of timber structural elements and the development of a generic framework for the assessment of the life-cycle vulnerability and robustness of timber structures....

  20. Sustainable Resilient, Robust & Resplendent Enterprises

    DEFF Research Database (Denmark)

    Edgeman, Rick

    to their impact. Resplendent enterprises are introduced with resplendence referring not to some sort of public or private façade, but instead refers to organizations marked by dual brilliance and nobility of strategy, governance and comportment that yields superior and sustainable triple bottom line performance....... Herein resilience, robustness, and resplendence (R3) are integrated with sustainable enterprise excellence (Edgeman and Eskildsen, 2013) or SEE and social-ecological innovation (Eskildsen and Edgeman, 2012) to aid progress of a firm toward producing continuously relevant performance that proceed from...

  1. Robust Fringe Projection Profilometry via Sparse Representation.

    Science.gov (United States)

    Budianto; Lun, Daniel P K

    2016-04-01

    In this paper, a robust fringe projection profilometry (FPP) algorithm using the sparse dictionary learning and sparse coding techniques is proposed. When reconstructing the 3D model of objects, traditional FPP systems often fail to perform if the captured fringe images have a complex scene, such as having multiple and occluded objects. It introduces great difficulty to the phase unwrapping process of an FPP system that can result in serious distortion in the final reconstructed 3D model. For the proposed algorithm, it encodes the period order information, which is essential to phase unwrapping, into some texture patterns and embeds them to the projected fringe patterns. When the encoded fringe image is captured, a modified morphological component analysis and a sparse classification procedure are performed to decode and identify the embedded period order information. It is then used to assist the phase unwrapping process to deal with the different artifacts in the fringe images. Experimental results show that the proposed algorithm can significantly improve the robustness of an FPP system. It performs equally well no matter the fringe images have a simple or complex scene, or are affected due to the ambient lighting of the working environment.

  2. Robust hashing for 3D models

    Science.gov (United States)

    Berchtold, Waldemar; Schäfer, Marcel; Rettig, Michael; Steinebach, Martin

    2014-02-01

    3D models and applications are of utmost interest in both science and industry. With the increment of their usage, their number and thereby the challenge to correctly identify them increases. Content identification is commonly done by cryptographic hashes. However, they fail as a solution in application scenarios such as computer aided design (CAD), scientific visualization or video games, because even the smallest alteration of the 3D model, e.g. conversion or compression operations, massively changes the cryptographic hash as well. Therefore, this work presents a robust hashing algorithm for 3D mesh data. The algorithm applies several different bit extraction methods. They are built to resist desired alterations of the model as well as malicious attacks intending to prevent correct allocation. The different bit extraction methods are tested against each other and, as far as possible, the hashing algorithm is compared to the state of the art. The parameters tested are robustness, security and runtime performance as well as False Acceptance Rate (FAR) and False Rejection Rate (FRR), also the probability calculation of hash collision is included. The introduced hashing algorithm is kept adaptive e.g. in hash length, to serve as a proper tool for all applications in practice.

  3. Robustness of mission plans for unmanned aircraft

    Science.gov (United States)

    Niendorf, Moritz

    , and criticalities are derived. This analysis is extended to Euclidean minimum spanning trees. This thesis aims at enabling increased mission performance by providing means of assessing the robustness and optimality of a mission and methods for identifying critical elements. Examples of the application to mission planning in contested environments, cargo aircraft mission planning, multi-objective mission planning, and planning optimal communication topologies for teams of unmanned aircraft are given.

  4. Perspective: Evolution and detection of genetic robustness

    NARCIS (Netherlands)

    Visser, de J.A.G.M.; Hermisson, J.; Wagner, G.P.; Ancel Meyers, L.; Bagheri-Chaichian, H.; Blanchard, J.L.; Chao, L.; Cheverud, J.M.; Elena, S.F.; Fontana, W.; Gibson, G.; Hansen, T.F.; Krakauer, D.; Lewontin, R.C.; Ofria, C.; Rice, S.H.; Dassow, von G.; Wagner, A.; Whitlock, M.C.

    2003-01-01

    Robustness is the invariance of phenotypes in the face of perturbation. The robustness of phenotypes appears at various levels of biological organization, including gene expression, protein folding, metabolic flux, physiological homeostasis, development, and even organismal fitness. The mechanisms

  5. Robust lyapunov controller for uncertain systems

    KAUST Repository

    Laleg-Kirati, Taous-Meriem; Elmetennani, Shahrazed

    2017-01-01

    Various examples of systems and methods are provided for Lyapunov control for uncertain systems. In one example, a system includes a process plant and a robust Lyapunov controller configured to control an input of the process plant. The robust

  6. Robust distributed cognitive relay beamforming

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2012-05-01

    In this paper, we present a distributed relay beamformer design for a cognitive radio network in which a cognitive (or secondary) transmit node communicates with a secondary receive node assisted by a set of cognitive non-regenerative relays. The secondary nodes share the spectrum with a licensed primary user (PU) node, and each node is assumed to be equipped with a single transmit/receive antenna. The interference to the PU resulting from the transmission from the cognitive nodes is kept below a specified limit. The proposed robust cognitive relay beamformer design seeks to minimize the total relay transmit power while ensuring that the transceiver signal-to-interference- plus-noise ratio and PU interference constraints are satisfied. The proposed design takes into account a parameter of the error in the channel state information (CSI) to render the performance of the beamformer robust in the presence of imperfect CSI. Though the original problem is non-convex, we show that the proposed design can be reformulated as a tractable convex optimization problem that can be solved efficiently. Numerical results are provided and illustrate the performance of the proposed designs for different network operating conditions and parameters. © 2012 IEEE.

  7. Robust canonical correlations: A comparative study

    OpenAIRE

    Branco, JA; Croux, Christophe; Filzmoser, P; Oliveira, MR

    2005-01-01

    Several approaches for robust canonical correlation analysis will be presented and discussed. A first method is based on the definition of canonical correlation analysis as looking for linear combinations of two sets of variables having maximal (robust) correlation. A second method is based on alternating robust regressions. These methods axe discussed in detail and compared with the more traditional approach to robust canonical correlation via covariance matrix estimates. A simulation study ...

  8. Production monitoring system for understanding product robustness

    DEFF Research Database (Denmark)

    Boorla, Srinivasa Murthy; Howard, Thomas J.

    2016-01-01

    study is used to demonstrate how the monitoring system can be used to efficiently guide corrective action to improve product performance. It is claimed that the monitoring system can be used to dramatically cut the time taken to identify, planand execute corrective action related to typical quality......In the current quality paradigm, the performance of a product is kept within specification by ensuring that its parts are within specification. Product performance is then validated after final assembly. However, this does not control how robust the product performance is, i.e. how much...... it will vary between the specification limits. In this paper, a model for predicting product performance is proposed, taking into account design, assembly and process parameters live from production. This empowers production to maintain final product performance, instead of part quality. The PRECI‐IN case...

  9. Robust adaptive synchronization of general dynamical networks ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 6. Robust ... A robust adaptive synchronization scheme for these general complex networks with multiple delays and uncertainties is established and raised by employing the robust adaptive control principle and the Lyapunov stability theory. We choose ...

  10. Robust portfolio selection under norm uncertainty

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2016-06-01

    Full Text Available Abstract In this paper, we consider the robust portfolio selection problem which has a data uncertainty described by the ( p , w $(p,w$ -norm in the objective function. We show that the robust formulation of this problem is equivalent to a linear optimization problem. Moreover, we present some numerical results concerning our robust portfolio selection problem.

  11. A robust standard deviation control chart

    NARCIS (Netherlands)

    Schoonhoven, M.; Does, R.J.M.M.

    2012-01-01

    This article studies the robustness of Phase I estimators for the standard deviation control chart. A Phase I estimator should be efficient in the absence of contaminations and resistant to disturbances. Most of the robust estimators proposed in the literature are robust against either diffuse

  12. Methodology in robust and nonparametric statistics

    CERN Document Server

    Jurecková, Jana; Picek, Jan

    2012-01-01

    Introduction and SynopsisIntroductionSynopsisPreliminariesIntroductionInference in Linear ModelsRobustness ConceptsRobust and Minimax Estimation of LocationClippings from Probability and Asymptotic TheoryProblemsRobust Estimation of Location and RegressionIntroductionM-EstimatorsL-EstimatorsR-EstimatorsMinimum Distance and Pitman EstimatorsDifferentiable Statistical FunctionsProblemsAsymptotic Representations for L-Estimators

  13. (-)[125I]-iodopindolol, a new highly selective radioiodinated beta-adrenergic receptor antagonist: measurement of beta-receptors on intact rat astrocytoma cells

    International Nuclear Information System (INIS)

    Barovsky, K.; Brooker, G.

    1980-01-01

    (-)-Pindolol, one of the most potent beta-adrenergic receptor antagonists, was radioiodinated using chloramine-T oxidation of carrier-free Na 125I and separated from unreacted pindolol to yield 2200 Ci/mmole (-)-[125I]-iodopindolol ((-)-[125I]-IPin). Mass and ultraviolet spectra confirmed that the iodination occurred on the indole ring, presumably at the 3 position. The binding of radiolabeled (-)-[125I]-IPin to beta-adrenergic receptors has been studied using intact C6 rat astrocytoma cells (2B subclone) grown in monolayer cultures. Binding of (-)[125IPin was saturable with time and concentration. Using 13 pM (-)-[125I]IPin, binding equilibrium was reached in 90 min at 21-22 degrees C. The reverse rate constant was 0.026 min-1 at 21 0 C. Specific binding (expressed as 1 microM(-)-propranolol displaceable counts) of (-)-[125I]-IPin was 95% of total binding. Scatchard analysis of (-)-[125I]-I]Pin binding revealed approximately 4300 receptors/cell and a dissociation constant of 30 pM. This was in excellent agreement with the kinetically determined dissociation constant of 35 pM. Displacement by propranolol and isoproterenol showed that (-)-[125I]-IPin binding sites were pharmacologically and stereospecifically selective. These results indicate that (-)-[125I]-IPin, a pure (-)-stereoisomer, high specific activity radioligand, selectively binds to beta-adrenergic receptors in whole cells with a high percentage of specific binding and should therefore be useful in the study and measurement of cellular beta-adrenergic receptors

  14. Pilocytic astrocytoma following radiotherapy for craniopharyngioma: case report Astrocitoma pilocítico pós-radioterapia para tratamento de craniofaringioma: relato de caso

    Directory of Open Access Journals (Sweden)

    LEONARDO BONILHA

    2000-09-01

    Full Text Available Administration of fractionated doses of irradiation is part of the adjutant therapy for CNS tumours such as craniopharyngiomas and pituitary adenomas. It can maximise cure rates or expand symptom-free period. Among the adverse effects of radiotherapy, the induction of a new tumour within the irradiated field has been frequently described. The precise clinical features that correlate irradiation and oncogenesis are not completely defined, but some authors have suggested that tumors are radiation induced when they are histologically different from the treated ones, arise in greater frequency in irradiated patients than among normal population and tend to occur in younger people with an unusual aggressiveness. In this article, we report a case of a papillary astrocytoma arising in a rather unusual latency period following radiotherapy for craniopharyngioma.A administração de doses fracionadas de radiação é parte do tratamento adjuvante de tumores do sistema nervoso central como craniofaringiomas ou adenomas hipofisários. A radioterapia pode aumentar as chances de cura ou expandir o período livre de sintomas. Dentre seus efeitos adversos, é conhecida a possibilidade de aparecimento de novo tumor na região irradiada. Os critérios que definem se um novo tumor é de fato induzido por radiação ainda não são completamente definidos. Adimite-se, no entanto, que se o novo tumor é histologicamente diferente do primeiro, aparece em indivíduos mais jovens e é mais agressivo que o habitual, provavelmente sua origem é devida à oncogênese da irradiação. Descrevemos um caso de astrocitoma pilocítico possivelmente induzido por radioterapia, com surgimento em tempo de latência inesperadamente curto.

  15. SU-E-J-212: MR Diffusion Tensor Imaging for Assessment of Tumor and Normal Brain Tissue Responses of Juvenile Pilocytic Astrocytoma Treated by Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Hou, P; Park, P; Li, H; Zhu, X; Mahajan, A; Grosshans, D [M.D. Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: Diffusion tensor imaging (DTI) can measure molecular mobility at the cellular level, quantified by the apparent diffusion coefficient (ADC). DTI may also reveal axonal fiber directional information in the white matter, quantified by the fractional anisotropy (FA). Juvenile pilocytic astrocytoma (JPA) is a rare brain tumor that occurs in children and young adults. Proton therapy (PT) is increasingly used in the treatment of pediatric brain tumors including JPA. However, the response of both tumors and normal tissues to PT is currently under investigation. We report tumor and normal brain tissue responses for a pediatric case of JPA treated with PT assessed using DTI. Methods: A ten year old male with JPA of the left thalamus received passive scattered PT to a dose of 50.4 Gy (RBE) in 28 fractions. Post PT, the patient has been followed up in seven years. At each follow up, MRI imaging including DTI was performed to assess response. MR images were registered to the treatment planning CT and the GTV mapped onto each MRI. The GTV contour was then mirrored to the right side of brain through the patient’s middle line to represent normal brain tissue. ADC and FA were measured within the ROIs. Results: Proton therapy can completely spare contra lateral brain while the target volume received full prescribed dose. From a series of MRI ADC images before and after PT at different follow ups, the enhancement corresponding to GTV had nearly disappeared more than 2 years after PT. Both ADC and FA demonstrate that contralateral normal brain tissue were not affect by PT and the tumor volume reverted to normal ADC and FA values. Conclusion: DTI allowed quantitative evaluation of tumor and normal brain tissue responses to PT. Further study in a larger cohort is warranted.

  16. SU-E-J-212: MR Diffusion Tensor Imaging for Assessment of Tumor and Normal Brain Tissue Responses of Juvenile Pilocytic Astrocytoma Treated by Proton Therapy

    International Nuclear Information System (INIS)

    Hou, P; Park, P; Li, H; Zhu, X; Mahajan, A; Grosshans, D

    2015-01-01

    Purpose: Diffusion tensor imaging (DTI) can measure molecular mobility at the cellular level, quantified by the apparent diffusion coefficient (ADC). DTI may also reveal axonal fiber directional information in the white matter, quantified by the fractional anisotropy (FA). Juvenile pilocytic astrocytoma (JPA) is a rare brain tumor that occurs in children and young adults. Proton therapy (PT) is increasingly used in the treatment of pediatric brain tumors including JPA. However, the response of both tumors and normal tissues to PT is currently under investigation. We report tumor and normal brain tissue responses for a pediatric case of JPA treated with PT assessed using DTI. Methods: A ten year old male with JPA of the left thalamus received passive scattered PT to a dose of 50.4 Gy (RBE) in 28 fractions. Post PT, the patient has been followed up in seven years. At each follow up, MRI imaging including DTI was performed to assess response. MR images were registered to the treatment planning CT and the GTV mapped onto each MRI. The GTV contour was then mirrored to the right side of brain through the patient’s middle line to represent normal brain tissue. ADC and FA were measured within the ROIs. Results: Proton therapy can completely spare contra lateral brain while the target volume received full prescribed dose. From a series of MRI ADC images before and after PT at different follow ups, the enhancement corresponding to GTV had nearly disappeared more than 2 years after PT. Both ADC and FA demonstrate that contralateral normal brain tissue were not affect by PT and the tumor volume reverted to normal ADC and FA values. Conclusion: DTI allowed quantitative evaluation of tumor and normal brain tissue responses to PT. Further study in a larger cohort is warranted

  17. From the Cover: Vulnerability of C6 Astrocytoma Cells After Single-Compound and Joint Exposure to Type I and Type II Pyrethroid Insecticides.

    Science.gov (United States)

    Romero, Delfina M; Berardino, Bruno G; Wolansky, Marcelo J; Kotler, Mónica L

    2017-01-01

    A primary mode-of-action of all pyrethroid insecticides (PYRs) is the disruption of the voltage-gated sodium channel electrophysiology in neurons of target pests and nontarget species. The neurological actions of PYRs on non-neuronal cells of the nervous system remain poorly investigated. In the present work, we used C6 astrocytoma cells to study PYR actions (0.1-50 μM) under the hypothesis that glial cells may be targeted by and vulnerable to PYRs. To this end, we characterized the effects of bifenthrin (BF), tefluthrin (TF), α-cypermethrin (α-CYP), and deltamethrin (DM) on the integrity of nuclear, mitochondrial, and lysosomal compartments. In general, 24- to 48-h exposures produced concentration-related impairment of cell viability. In single-compound, 24-h exposure experiments, effective concentration (EC) 15 s 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT assay) were computed as follows (in μM): BF, 16.1; TF, 37.3; α-CYP, 7.8; DM, 5.0. We found concentration-related damage in several C6-cell subcellular compartments (mitochondria, nuclei, and lysosomes) at ≥ 10 -1 μM levels. Last, we examined a mixture of all PYRs (ie, Σ individual EC 15 ) using MTT assays and subcellular analyses. Our findings indicate that C6 cells are responsive to nM levels of PYRs, suggesting that astroglial susceptibility may contribute to the low-dose neurological effects caused by these insecticides. This research further suggests that C6 cells may provide relevant information as a screening platform for pesticide mixtures targeting nervous system cells by expected and unexpected toxicogenic pathways potentially contributing to clinical neurotoxicity. © The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  18. Robust matching for voice recognition

    Science.gov (United States)

    Higgins, Alan; Bahler, L.; Porter, J.; Blais, P.

    1994-10-01

    This paper describes an automated method of comparing a voice sample of an unknown individual with samples from known speakers in order to establish or verify the individual's identity. The method is based on a statistical pattern matching approach that employs a simple training procedure, requires no human intervention (transcription, work or phonetic marketing, etc.), and makes no assumptions regarding the expected form of the statistical distributions of the observations. The content of the speech material (vocabulary, grammar, etc.) is not assumed to be constrained in any way. An algorithm is described which incorporates frame pruning and channel equalization processes designed to achieve robust performance with reasonable computational resources. An experimental implementation demonstrating the feasibility of the concept is described.

  19. Robustness Assessment of Spatial Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning

    2012-01-01

    Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures many modern buildi...... to robustness of spatial timber structures and will discuss the consequences of such robustness issues related to the future development of timber structures.......Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures many modern building...... codes consider the need for robustness of structures and provide strategies and methods to obtain robustness. Therefore a structural engineer may take necessary steps to design robust structures that are insensitive to accidental circumstances. The present paper summaries issues with respect...

  20. Enabling Rapid and Robust Structural Analysis During Conceptual Design

    Science.gov (United States)

    Eldred, Lloyd B.; Padula, Sharon L.; Li, Wu

    2015-01-01

    This paper describes a multi-year effort to add a structural analysis subprocess to a supersonic aircraft conceptual design process. The desired capabilities include parametric geometry, automatic finite element mesh generation, static and aeroelastic analysis, and structural sizing. The paper discusses implementation details of the new subprocess, captures lessons learned, and suggests future improvements. The subprocess quickly compares concepts and robustly handles large changes in wing or fuselage geometry. The subprocess can rank concepts with regard to their structural feasibility and can identify promising regions of the design space. The automated structural analysis subprocess is deemed robust and rapid enough to be included in multidisciplinary conceptual design and optimization studies.

  1. Robust design principles for reducing variation in functional performance

    DEFF Research Database (Denmark)

    Christensen, Martin Ebro; Howard, Thomas J.

    2016-01-01

    This paper identifies, describes and classifies a comprehensive collection of variation reduction principles (VRP) that can be used to increase the robustness of a product and reduce its variation in functional performance. Performance variation has a negative effect on the reliability and percei......This paper identifies, describes and classifies a comprehensive collection of variation reduction principles (VRP) that can be used to increase the robustness of a product and reduce its variation in functional performance. Performance variation has a negative effect on the reliability...... and perceived quality of a product and efforts should be made to minimise it. The design principles are identified by a systematic decomposition of the Taguchi Transfer Function in combination with the use of existing literature and the authors’ experience. The paper presents 15 principles and describes...... their advantages and disadvantages along with example cases. Subsequently, the principles are classified based on their applicability in the various development and production stages. The VRP are to be added to existing robust design methodologies, helping the designer to think beyond robust design tool and method...

  2. Robust network topologies for generating switch-like cellular responses.

    Directory of Open Access Journals (Sweden)

    Najaf A Shah

    2011-06-01

    Full Text Available Signaling networks that convert graded stimuli into binary, all-or-none cellular responses are critical in processes ranging from cell-cycle control to lineage commitment. To exhaustively enumerate topologies that exhibit this switch-like behavior, we simulated all possible two- and three-component networks on random parameter sets, and assessed the resulting response profiles for both steepness (ultrasensitivity and extent of memory (bistability. Simulations were used to study purely enzymatic networks, purely transcriptional networks, and hybrid enzymatic/transcriptional networks, and the topologies in each class were rank ordered by parametric robustness (i.e., the percentage of applied parameter sets exhibiting ultrasensitivity or bistability. Results reveal that the distribution of network robustness is highly skewed, with the most robust topologies clustering into a small number of motifs. Hybrid networks are the most robust in generating ultrasensitivity (up to 28% and bistability (up to 18%; strikingly, a purely transcriptional framework is the most fragile in generating either ultrasensitive (up to 3% or bistable (up to 1% responses. The disparity in robustness among the network classes is due in part to zero-order ultrasensitivity, an enzyme-specific phenomenon, which repeatedly emerges as a particularly robust mechanism for generating nonlinearity and can act as a building block for switch-like responses. We also highlight experimentally studied examples of topologies enabling switching behavior, in both native and synthetic systems, that rank highly in our simulations. This unbiased approach for identifying topologies capable of a given response may be useful in discovering new natural motifs and in designing robust synthetic gene networks.

  3. Robustness Area Technique Developing Guidelines for Power System Restoration

    Directory of Open Access Journals (Sweden)

    Paulo Murinelli Pesoti

    2017-01-01

    Full Text Available This paper proposes a novel energy based technique called the Robustness Area (RA technique that measures power system robustness levels, as a helper for planning Power System Restorations (PSRs. The motivation is on account of the latest blackouts in Brazil, where the local Independent System Operator (ISO encountered difficulties related to circuit disconnections during the restoration. The technique identifies vulnerable and robust buses, pointing out system areas that should be firstly reinforced during PSR, in order to enhance system stability. A Brazilian power system restoration area is used to compare the guidelines adopted by the ISO with a more suitable new plan indicated by the RA tool. Active power and reactive power load margin and standing phase angle show the method efficiency as a result of a well balanced system configuration, enhancing the restoration performance. Time domain simulations for loop closures and severe events also show the positive impact that the proposed tool brings to PSRs.

  4. Integrating robust timetabling in line plan optimization for railway systems

    DEFF Research Database (Denmark)

    Burggraeve, Sofie; Bull, Simon Henry; Vansteenwegen, Pieter

    2017-01-01

    We propose a heuristic algorithm to build a railway line plan from scratch that minimizes passenger travel time and operator cost and for which a feasible and robust timetable exists. A line planning module and a timetabling module work iteratively and interactively. The line planning module......, but is constrained by limited shunt capacity. While the operator and passenger cost remain close to those of the initially and (for these costs) optimally built line plan, the timetable corresponding to the finally developed robust line plan significantly improves the minimum buffer time, and thus the robustness...... creates an initial line plan. The timetabling module evaluates the line plan and identifies a critical line based on minimum buffer times between train pairs. The line planning module proposes a new line plan in which the time length of the critical line is modified in order to provide more flexibility...

  5. Robust input design for nonlinear dynamic modeling of AUV.

    Science.gov (United States)

    Nouri, Nowrouz Mohammad; Valadi, Mehrdad

    2017-09-01

    Input design has a dominant role in developing the dynamic model of autonomous underwater vehicles (AUVs) through system identification. Optimal input design is the process of generating informative inputs that can be used to generate the good quality dynamic model of AUVs. In a problem with optimal input design, the desired input signal depends on the unknown system which is intended to be identified. In this paper, the input design approach which is robust to uncertainties in model parameters is used. The Bayesian robust design strategy is applied to design input signals for dynamic modeling of AUVs. The employed approach can design multiple inputs and apply constraints on an AUV system's inputs and outputs. Particle swarm optimization (PSO) is employed to solve the constraint robust optimization problem. The presented algorithm is used for designing the input signals for an AUV, and the estimate obtained by robust input design is compared with that of the optimal input design. According to the results, proposed input design can satisfy both robustness of constraints and optimality. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  6. Robust holographic storage system design.

    Science.gov (United States)

    Watanabe, Takahiro; Watanabe, Minoru

    2011-11-21

    Demand is increasing daily for large data storage systems that are useful for applications in spacecraft, space satellites, and space robots, which are all exposed to radiation-rich space environment. As candidates for use in space embedded systems, holographic storage systems are promising because they can easily provided the demanded large-storage capability. Particularly, holographic storage systems, which have no rotation mechanism, are demanded because they are virtually maintenance-free. Although a holographic memory itself is an extremely robust device even in a space radiation environment, its associated lasers and drive circuit devices are vulnerable. Such vulnerabilities sometimes engendered severe problems that prevent reading of all contents of the holographic memory, which is a turn-off failure mode of a laser array. This paper therefore presents a proposal for a recovery method for the turn-off failure mode of a laser array on a holographic storage system, and describes results of an experimental demonstration. © 2011 Optical Society of America

  7. Efficient robust conditional random fields.

    Science.gov (United States)

    Song, Dongjin; Liu, Wei; Zhou, Tianyi; Tao, Dacheng; Meyer, David A

    2015-10-01

    Conditional random fields (CRFs) are a flexible yet powerful probabilistic approach and have shown advantages for popular applications in various areas, including text analysis, bioinformatics, and computer vision. Traditional CRF models, however, are incapable of selecting relevant features as well as suppressing noise from noisy original features. Moreover, conventional optimization methods often converge slowly in solving the training procedure of CRFs, and will degrade significantly for tasks with a large number of samples and features. In this paper, we propose robust CRFs (RCRFs) to simultaneously select relevant features. An optimal gradient method (OGM) is further designed to train RCRFs efficiently. Specifically, the proposed RCRFs employ the l1 norm of the model parameters to regularize the objective used by traditional CRFs, therefore enabling discovery of the relevant unary features and pairwise features of CRFs. In each iteration of OGM, the gradient direction is determined jointly by the current gradient together with the historical gradients, and the Lipschitz constant is leveraged to specify the proper step size. We show that an OGM can tackle the RCRF model training very efficiently, achieving the optimal convergence rate [Formula: see text] (where k is the number of iterations). This convergence rate is theoretically superior to the convergence rate O(1/k) of previous first-order optimization methods. Extensive experiments performed on three practical image segmentation tasks demonstrate the efficacy of OGM in training our proposed RCRFs.

  8. Robust boosting via convex optimization

    Science.gov (United States)

    Rätsch, Gunnar

    2001-12-01

    In this work we consider statistical learning problems. A learning machine aims to extract information from a set of training examples such that it is able to predict the associated label on unseen examples. We consider the case where the resulting classification or regression rule is a combination of simple rules - also called base hypotheses. The so-called boosting algorithms iteratively find a weighted linear combination of base hypotheses that predict well on unseen data. We address the following issues: o The statistical learning theory framework for analyzing boosting methods. We study learning theoretic guarantees on the prediction performance on unseen examples. Recently, large margin classification techniques emerged as a practical result of the theory of generalization, in particular Boosting and Support Vector Machines. A large margin implies a good generalization performance. Hence, we analyze how large the margins in boosting are and find an improved algorithm that is able to generate the maximum margin solution. o How can boosting methods be related to mathematical optimization techniques? To analyze the properties of the resulting classification or regression rule, it is of high importance to understand whether and under which conditions boosting converges. We show that boosting can be used to solve large scale constrained optimization problems, whose solutions are well characterizable. To show this, we relate boosting methods to methods known from mathematical optimization, and derive convergence guarantees for a quite general family of boosting algorithms. o How to make Boosting noise robust? One of the problems of current boosting techniques is that they are sensitive to noise in the training sample. In order to make boosting robust, we transfer the soft margin idea from support vector learning to boosting. We develop theoretically motivated regularized algorithms that exhibit a high noise robustness. o How to adapt boosting to regression problems

  9. Robust satellite techniques for monitoring volcanic eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Pergola, N.; Pietrapertosa, C. [Consiglio Nazionale delle Ricerche, Istituto di Metodologie Avanzate, Tito Scalo, PZ (Italy); Lacava, T.; Tramutoli, V. [Potenza Universita' della Basilicata, Potenza (Italy). Dipt. di Ingegneria e Fisica dell' Ambiente

    2001-04-01

    Through this paper the robust approach to monitoring volcanic aerosols by satellite is applied to an extended set of events affecting Stromboli and Etna volcanoes to assess its performance in automated detection of eruptive clouds and in monitoring pre-eruptive emission activities. Using only NOAA/AVHRR data at hand (without any specific atmospheric model or ancillary ground-based measurements) the proposed method automatically discriminates meteorological from eruptive volcanic clouds and, in several cases, identified pre-eruptive anomalies in the emission rates not identified by traditional methods. The main merit of this approach is its effectiveness in recognising field anomalies also in the presence of a highly variable surface background as well as its intrinsic exportability not only on different geographic areas but also on different satellite instrumental packages. In particular, the possibility to extend the proposed method to the incoming new MSG/SEVIRI satellite package (which is going to fly next year) with its improved spectral (specific bands for SO{sub 2}) and temporal (up to 15 min) resolutions has been evaluated representing the natural continuation of this work.

  10. Robust AIC with High Breakdown Scale Estimate

    Directory of Open Access Journals (Sweden)

    Shokrya Saleh

    2014-01-01

    Full Text Available Akaike Information Criterion (AIC based on least squares (LS regression minimizes the sum of the squared residuals; LS is sensitive to outlier observations. Alternative criterion, which is less sensitive to outlying observation, has been proposed; examples are robust AIC (RAIC, robust Mallows Cp (RCp, and robust Bayesian information criterion (RBIC. In this paper, we propose a robust AIC by replacing the scale estimate with a high breakdown point estimate of scale. The robustness of the proposed methods is studied through its influence function. We show that, the proposed robust AIC is effective in selecting accurate models in the presence of outliers and high leverage points, through simulated and real data examples.

  11. Multimodel Robust Control for Hydraulic Turbine

    OpenAIRE

    Osuský, Jakub; Števo, Stanislav

    2014-01-01

    The paper deals with the multimodel and robust control system design and their combination based on M-Δ structure. Controller design will be done in the frequency domain with nominal performance specified by phase margin. Hydraulic turbine model is analyzed as system with unstructured uncertainty, and robust stability condition is included in controller design. Multimodel and robust control approaches are presented in detail on hydraulic turbine model. Control design approaches are compared a...

  12. Forecasting exchange rates: a robust regression approach

    OpenAIRE

    Preminger, Arie; Franck, Raphael

    2005-01-01

    The least squares estimation method as well as other ordinary estimation method for regression models can be severely affected by a small number of outliers, thus providing poor out-of-sample forecasts. This paper suggests a robust regression approach, based on the S-estimation method, to construct forecasting models that are less sensitive to data contamination by outliers. A robust linear autoregressive (RAR) and a robust neural network (RNN) models are estimated to study the predictabil...

  13. Evaluation of amentoflavone isolated from Cnestis ferruginea Vahl ex DC (Connaraceae) on production of inflammatory mediators in LPS stimulated rat astrocytoma cell line (C6) and THP-1 cells.

    Science.gov (United States)

    Ishola, I O; Chaturvedi, J P; Rai, S; Rajasekar, N; Adeyemi, O O; Shukla, R; Narender, T

    2013-03-27

    Cnestisferruginea (CF) Vahl ex DC (Connaraceae) is a shrub widely used in traditional African medicine for the treatment of various psychiatric illness and inflammatory conditions. This study was carried out to investigate the effect of amentoflavone isolated from methanolic root extract of CF on lipopolysaccharide (LPS)-induced neuroinflammatory cascade of events associated to the oxidative and nitrative stress, and TNF-α production in rat astrocytoma cell line (C6) and human monocytic leukemia cell line (THP-1), respectively. Rat astrocytoma cells (C6) were stimulated with LPS (10μg/ml) alone and in the presence of different concentrations of amentoflavone (0.1-3μg/ml) for 24h incubation period. Nitrite release, reactive oxygen species (ROS), malondialdehyde (MDA) and reduced-glutathione (GSH) in C6 cells were estimated; while the TNF-α level was estimated in THP-1 cell lysate. In vivo analgesic activity was evaluated using mouse writhing and hot plate tests while the anti-inflammatory effect was investigated using carrageenan-induced oedema test. LPS (10μg/ml) significantly (PTHP-1 cells. Amentoflavone (6.25-50mg/kg) significantly (Ptest. It produced time course significant (P<0.05) decrease in oedema formation in rodents. Findings in this study demonstrate the anti-neuroinflammatory and antinoceptive effects of amentoflavone which may suggest its beneficial roles in neuroinflammation associated disorders. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  14. Robustness: confronting lessons from physics and biology.

    Science.gov (United States)

    Lesne, Annick

    2008-11-01

    The term robustness is encountered in very different scientific fields, from engineering and control theory to dynamical systems to biology. The main question addressed herein is whether the notion of robustness and its correlates (stability, resilience, self-organisation) developed in physics are relevant to biology, or whether specific extensions and novel frameworks are required to account for the robustness properties of living systems. To clarify this issue, the different meanings covered by this unique term are discussed; it is argued that they crucially depend on the kind of perturbations that a robust system should by definition withstand. Possible mechanisms underlying robust behaviours are examined, either encountered in all natural systems (symmetries, conservation laws, dynamic stability) or specific to biological systems (feedbacks and regulatory networks). Special attention is devoted to the (sometimes counterintuitive) interrelations between robustness and noise. A distinction between dynamic selection and natural selection in the establishment of a robust behaviour is underlined. It is finally argued that nested notions of robustness, relevant to different time scales and different levels of organisation, allow one to reconcile the seemingly contradictory requirements for robustness and adaptability in living systems.

  15. Robustness of Long Span Reciprocal Timber Structures

    DEFF Research Database (Denmark)

    Balfroid, Nathalie; Kirkegaard, Poul Henning

    2011-01-01

    engineer may take necessary steps to design robust structures that are insensitive to accidental circumstances. The present paper makes a discussion of such robustness issues related to the future development of reciprocal timber structures. The paper concludes that these kind of structures can have...... a potential as long span timber structures in real projects if they are carefully designed with respect to the overall robustness strategies.......Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. The interest has also been facilitated due to recently severe structural failures...

  16. Small regions of overlapping deletions on 6q26 in human astrocytic tumours identified using chromosome 6 tile path array CGH

    Science.gov (United States)

    Ichimura, Koichi; Mungall, Andrew J; Fiegler, Heike; Pearson, Danita M.; Dunham, Ian; Carter, Nigel P; Collins, V. Peter

    2009-01-01

    Deletions of chromosome 6 are a common abnormality in diverse human malignancies including astrocytic tumours, suggesting the presence of tumour suppressor genes (TSG). In order to help identify candidate TSGs, we have constructed a chromosome 6 tile path microarray. The array contains 1780 clones (778 PACs and 1002 BACs) that cover 98.3% of the published chromosome 6 sequences. A total of 104 adult astrocytic tumours (10 diffuse astrocytomas, 30 anaplastic astrocytomas (AA), 64 glioblastomas (GB)) were analysed using this array. Single copy number change was successfully detected and the result was in general concordant with a microsatellite analysis. The pattern of copy number change was complex with multiple interstitial deletions/gains. However, a predominance of telomeric 6q deletions was seen. Two small common and overlapping regions of deletion at 6q26 were identified. One was 1002 kb in size and contained PACRG and QKI, while the second was 199 kb and harbours a single gene, ARID1B. The data show that the chromosome 6 tile path array is useful in mapping copy number changes with high resolution and accuracy. We confirmed the high frequency of chromosome 6 deletions in AA and GB, and identified two novel commonly deleted regions that may harbour TSGs. PMID:16205629

  17. Many-objective robust decision making for water allocation under climate change

    NARCIS (Netherlands)

    Yan, Dan; Ludwig, Fulco; Huang, He Qing; Werners, Saskia E.

    2017-01-01

    Water allocation is facing profound challenges due to climate change uncertainties. To identify adaptive water allocation strategies that are robust to climate change uncertainties, a model framework combining many-objective robust decision making and biophysical modeling is developed for large

  18. The effects of sequential versus concurrent chemotherapy and radiotherapy on survival and toxicity in patients with newly diagnosed high-grade astrocytoma

    International Nuclear Information System (INIS)

    Kleinberg, Lawrence; Grossman, Stuart A.; Piantadosi, Steven; Zeltzman, Michel; Wharam, Moody

    1999-01-01

    Purpose: To determine the effects of sequential versus concurrent administration of cranial radiotherapy and cisplatin/carmustine (BCNU) chemotherapy on survival and toxicity in newly diagnosed high-grade astrocytomas. Methods and Materials: From 1988 to 1996, 101 patients were treated on 2 therapeutic protocols for malignant glioma that used the identical chemotherapy regimen but differed in the timing of cranial radiotherapy. The eligibility criteria for the 2 protocols were identical. In the first protocol (1988-1991, 52 patients), cisplatin 120 mg/BCNU 120 mg i.v. over 72 h, was given for 3 monthly cycles prior to cranial radiotherapy. After a response rate of 42%, with a median survival of 13 months was achieved with this sequential regimen, a successor protocol (1992-1996, 49 patients) was developed in which cranial radiotherapy began concurrently with the start of the identical chemotherapy regimen. Chemotherapy was delayed but not discontinued if prolonged grade III/IV hematologic toxicity was experienced, but protocol therapy was discontinued if disease progression or thromboembolic events occurred. Survival outcome and hematologic toxicity were compared for the patients treated on these protocols. Results: Seventy-seven percent of sequentially-treated patients and 68% of concurrently-treated patients completed all planned therapy. Kaplan-Meier survival was similar to concurrent or sequential administration of chemotherapy and radiotherapy (median 12.8 months vs. 13.8 months, respectively). Hematologic toxicity was significantly less in sequentially- versus concurrently-treated patients, with median nadir per cycle (2.9 vs. 1.8 x 10 3 /mm 3 ) (p < 0.001), and incidence of grade 3/4 leukopenia 40% versus 77% (p = 0.002). There was also an increase in platelet transfusion requirements in concurrently-treated patients, but no significant worsening of anemia. We postulate that the worsened leukopenia results from the effects of concurrent radiotherapy on

  19. Huge heterogeneity in survival in a subset of adult patients with resected, wild-type isocitrate dehydrogenase status, WHO grade II astrocytomas.

    Science.gov (United States)

    Poulen, Gaëtan; Gozé, Catherine; Rigau, Valérie; Duffau, Hugues

    2018-04-20

    OBJECTIVE World Health Organization grade II gliomas are infiltrating tumors that inexorably progress to a higher grade of malignancy. However, the time to malignant transformation is quite unpredictable at the individual patient level. A wild-type isocitrate dehydrogenase (IDH-wt) molecular profile has been reported as a poor prognostic factor, with more rapid progression and a shorter survival compared with IDH-mutant tumors. Here, the oncological outcomes of a series of adult patients with IDH-wt, diffuse, WHO grade II astrocytomas (AII) who underwent resection without early adjuvant therapy were investigated. METHODS A retrospective review of patients extracted from a prospective database who underwent resection between 2007 and 2013 for histopathologically confirmed, IDH-wt, non-1p19q codeleted AII was performed. All patients had a minimum follow-up period of 2 years. Information regarding clinical, radiographic, and surgical results and survival were collected and analyzed. RESULTS Thirty-one consecutive patients (18 men and 13 women, median age 39.6 years) were included in this study. The preoperative median tumor volume was 54 cm 3 (range 3.5-180 cm 3 ). The median growth rate, measured as the velocity of diametric expansion, was 2.45 mm/year. The median residual volume after surgery was 4.2 cm 3 (range 0-30 cm 3 ) with a median volumetric extent of resection of 93.97% (8 patients had a total or supratotal resection). No patient experienced permanent neurological deficits after surgery, and all patients resumed a normal life. No immediate postoperative chemotherapy or radiation therapy was given. The median clinical follow-up duration from diagnosis was 74 months (range 27-157 months). In this follow-up period, 18 patients received delayed chemotherapy and/or radiotherapy for tumor progression. Five patients (16%) died at a median time from radiological diagnosis of 3.5 years (range 2.6-4.5 years). Survival from diagnosis was 77.27% at 5 years. None of the

  20. Phase III randomized study of radiation and temozolomide versus radiation and nitrosourea therapy for anaplastic astrocytoma: results of NRG Oncology RTOG 9813.

    Science.gov (United States)

    Chang, Susan; Zhang, Peixin; Cairncross, J Gregory; Gilbert, Mark R; Bahary, Jean-Paul; Dolinskas, Carol A; Chakravarti, Arnab; Aldape, Kenneth D; Bell, Erica H; Schiff, David; Jaeckle, Kurt; Brown, Paul D; Barger, Geoffrey R; Werner-Wasik, Maria; Shih, Helen; Brachman, David; Penas-Prado, Marta; Robins, H Ian; Belanger, Karl; Schultz, Christopher; Hunter, Grant; Mehta, Minesh

    2017-02-01

    The primary objective of this study was to compare the overall survival (OS) of patients with anaplastic astrocytoma (AA) treated with radiotherapy (RT) and either temozolomide (TMZ) or a nitrosourea (NU). Secondary endpoints were time to tumor progression (TTP), toxicity, and the effect of IDH1 mutation status on clinical outcome. Eligible patients with centrally reviewed, histologically confirmed, newly diagnosed AA were randomized to receive either RT+TMZ (n = 97) or RT+NU (n = 99). The study closed early because the target accrual rate was not met. Median follow-up time for patients still alive was 10.1 years (1.9-12.6 y); 66% of the patients died. Median survival time was 3.9 years in the RT/TMZ arm (95% CI, 3.0-7.0) and 3.8 years in the RT/NU arm (95% CI, 2.2-7.0), corresponding to a hazard ratio (HR) of 0.94 (P = .36; 95% CI, 0.67-1.32). The differences in progression-free survival (PFS) and TTP between the 2 arms were not statistically significant. Patients in the RT+NU arm experienced more grade ≥3 toxicity (75.8% vs 47.9%, P < .001), mainly related to myelosuppression. Of the 196 patients, 111 were tested for IDH1-R132H status (60 RT+TMZ and 51 RT+NU). Fifty-four patients were IDH negative and 49 were IDH positive with a better OS in IDH-positive patients (median survival time 7.9 vs 2.8 y; P = .004, HR = 0.50; 95% CI, 0.31-0.81). RT+TMZ did not appear to significantly improve OS or TTP for AA compared with RT+ NU. RT+TMZ was better tolerated. IDH1-R132H mutation was associated with longer survival. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

  1. Robust Adaptable Video Copy Detection

    DEFF Research Database (Denmark)

    Assent, Ira; Kremer, Hardy

    2009-01-01

    in contrast). Our query processing combines filtering and indexing structures for efficient multistep computation of video copies under this model. We show that our model successfully identifies altered video copies and does so more reliably than existing models.......Video copy detection should be capable of identifying video copies subject to alterations e.g. in video contrast or frame rates. We propose a video copy detection scheme that allows for adaptable detection of videos that are altered temporally (e.g. frame rate change) and/or visually (e.g. change...

  2. Implicitly Weighted Methods in Robust Image Analysis

    Czech Academy of Sciences Publication Activity Database

    Kalina, Jan

    2012-01-01

    Roč. 44, č. 3 (2012), s. 449-462 ISSN 0924-9907 R&D Projects: GA MŠk(CZ) 1M06014 Institutional research plan: CEZ:AV0Z10300504 Keywords : robustness * high breakdown point * outlier detection * robust correlation analysis * template matching * face recognition Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.767, year: 2012

  3. Structural Robustness Evaluation of Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Giuliani, Luisa; Bontempi, Franco

    2010-01-01

    in the framework of a safe design: it depends on different factors, like exposure, vulnerability and robustness. Particularly, the requirement of structural vulnerability and robustness are discussed in this paper and a numerical application is presented, in order to evaluate the effects of a ship collision...

  4. In Silico Design of Robust Bolalipid Membranes

    NARCIS (Netherlands)

    Bulacu, Monica; Periole, Xavier; Marrink, Siewert J.; Périole, Xavier

    The robustness of microorganisms used in industrial fermentations is essential for the efficiency and yield of the production process. A viable tool to increase the robustness is through engineering of the cell membrane and especially by incorporating lipids from species that survive under harsh

  5. Assessment of Process Robustness for Mass Customization

    DEFF Research Database (Denmark)

    Nielsen, Kjeld; Brunø, Thomas Ditlev

    2013-01-01

    robustness and their capability to develop it. Through literature study and analysis of robust process design characteristics a number of metrics are described which can be used for assessment. The metrics are evaluated and analyzed to be applied as KPI’s to help MC companies prioritize efforts in business...

  6. Applying Robust Design in an Industrial Context

    DEFF Research Database (Denmark)

    Christensen, Martin Ebro

    mechanical architectures. Furthermore a set of 15 robust design principles for reducing the variation in functional performance is compiled in a format directly supporting the work of the design engineer. With these foundational methods in place, the existing tools, methods and KPIs of Robust Design...

  7. The importance of robust design methodology

    DEFF Research Database (Denmark)

    Eifler, Tobias; Howard, Thomas J.

    2018-01-01

    infamous recalls in automotive history, that of the GM ignition switch, from the perspective of Robust Design. It is investigated if available Robust Design methods such as sensitivity analysis, tolerance stack-ups, design clarity, etc. would have been suitable to account for the performance variation...

  8. Robust Control Charts for Time Series Data

    NARCIS (Netherlands)

    Croux, C.; Gelper, S.; Mahieu, K.

    2010-01-01

    This article presents a control chart for time series data, based on the one-step- ahead forecast errors of the Holt-Winters forecasting method. We use robust techniques to prevent that outliers affect the estimation of the control limits of the chart. Moreover, robustness is important to maintain

  9. Efficient reanalysis techniques for robust topology optimization

    DEFF Research Database (Denmark)

    Amir, Oded; Sigmund, Ole; Lazarov, Boyan Stefanov

    2012-01-01

    efficient robust topology optimization procedures based on reanalysis techniques. The approach is demonstrated on two compliant mechanism design problems where robust design is achieved by employing either a worst case formulation or a stochastic formulation. It is shown that the time spent on finite...

  10. Extending the Scope of Robust Quadratic Optimization

    NARCIS (Netherlands)

    Marandi, Ahmadreza; Ben-Tal, A.; den Hertog, Dick; Melenberg, Bertrand

    In this paper, we derive tractable reformulations of the robust counterparts of convex quadratic and conic quadratic constraints with concave uncertainties for a broad range of uncertainty sets. For quadratic constraints with convex uncertainty, it is well-known that the robust counterpart is, in

  11. Security and robustness for collaborative monitors

    NARCIS (Netherlands)

    Testerink, Bas; Bulling, Nils; Dastani, Mehdi

    2016-01-01

    Decentralized monitors can be subject to robustness and security risks. Robustness risks include attacks on the monitor’s infrastructure in order to disable parts of its functionality. Security risks include attacks that try to extract information from the monitor and thereby possibly leak sensitive

  12. How Robust is Your System Resilience?

    Science.gov (United States)

    Homayounfar, M.; Muneepeerakul, R.

    2017-12-01

    Robustness and resilience are concepts in system thinking that have grown in importance and popularity. For many complex social-ecological systems, however, robustness and resilience are difficult to quantify and the connections and trade-offs between them difficult to study. Most studies have either focused on qualitative approaches to discuss their connections or considered only one of them under particular classes of disturbances. In this study, we present an analytical framework to address the linkage between robustness and resilience more systematically. Our analysis is based on a stylized dynamical model that operationalizes a widely used concept framework for social-ecological systems. The model enables us to rigorously define robustness and resilience and consequently investigate their connections. The results reveal the tradeoffs among performance, robustness, and resilience. They also show how the nature of the such tradeoffs varies with the choices of certain policies (e.g., taxation and investment in public infrastructure), internal stresses and external disturbances.

  13. A Survey on Robustness in Railway Planning

    DEFF Research Database (Denmark)

    Lusby, Richard Martin; Larsen, Jesper; Bull, Simon Henry

    2018-01-01

    Planning problems in passenger railway range from long term strategic decision making to the detailed planning of operations.Operations research methods have played an increasing role in this planning process. However, recently more attention has been given to considerations of robustness...... in the quality of solutions to individual planning problems, and of operations in general. Robustness in general is the capacity for some system to absorb or resist changes. In the context of railway robustness it is often taken to be the capacity for operations to continue at some level when faced...... with a disruption such as delay or failure. This has resulted in more attention given to the inclusion of robustness measures and objectives in individual planning problems, and to the providing of tools to ensure operations continue under disrupted situations. In this paper we survey the literature on robustness...

  14. International Conference on Robust Statistics 2015

    CERN Document Server

    Basu, Ayanendranath; Filzmoser, Peter; Mukherjee, Diganta

    2016-01-01

    This book offers a collection of recent contributions and emerging ideas in the areas of robust statistics presented at the International Conference on Robust Statistics 2015 (ICORS 2015) held in Kolkata during 12–16 January, 2015. The book explores the applicability of robust methods in other non-traditional areas which includes the use of new techniques such as skew and mixture of skew distributions, scaled Bregman divergences, and multilevel functional data methods; application areas being circular data models and prediction of mortality and life expectancy. The contributions are of both theoretical as well as applied in nature. Robust statistics is a relatively young branch of statistical sciences that is rapidly emerging as the bedrock of statistical analysis in the 21st century due to its flexible nature and wide scope. Robust statistics supports the application of parametric and other inference techniques over a broader domain than the strictly interpreted model scenarios employed in classical statis...

  15. Robust clustering of languages across Wikipedia growth

    Science.gov (United States)

    Ban, Kristina; Perc, Matjaž; Levnajić, Zoran

    2017-10-01

    Wikipedia is the largest existing knowledge repository that is growing on a genuine crowdsourcing support. While the English Wikipedia is the most extensive and the most researched one with over 5 million articles, comparatively little is known about the behaviour and growth of the remaining 283 smaller Wikipedias, the smallest of which, Afar, has only one article. Here, we use a subset of these data, consisting of 14 962 different articles, each of which exists in 26 different languages, from Arabic to Ukrainian. We study the growth of Wikipedias in these languages over a time span of 15 years. We show that, while an average article follows a random path from one language to another, there exist six well-defined clusters of Wikipedias that share common growth patterns. The make-up of these clusters is remarkably robust against the method used for their determination, as we verify via four different clustering methods. Interestingly, the identified Wikipedia clusters have little correlation with language families and groups. Rather, the growth of Wikipedia across different languages is governed by different factors, ranging from similarities in culture to information literacy.

  16. Robust clustering of languages across Wikipedia growth

    Science.gov (United States)

    Ban, Kristina; Levnajić, Zoran

    2017-01-01

    Wikipedia is the largest existing knowledge repository that is growing on a genuine crowdsourcing support. While the English Wikipedia is the most extensive and the most researched one with over 5 million articles, comparatively little is known about the behaviour and growth of the remaining 283 smaller Wikipedias, the smallest of which, Afar, has only one article. Here, we use a subset of these data, consisting of 14 962 different articles, each of which exists in 26 different languages, from Arabic to Ukrainian. We study the growth of Wikipedias in these languages over a time span of 15 years. We show that, while an average article follows a random path from one language to another, there exist six well-defined clusters of Wikipedias that share common growth patterns. The make-up of these clusters is remarkably robust against the method used for their determination, as we verify via four different clustering methods. Interestingly, the identified Wikipedia clusters have little correlation with language families and groups. Rather, the growth of Wikipedia across different languages is governed by different factors, ranging from similarities in culture to information literacy. PMID:29134106

  17. Robust signatures of solar neutrino oscillation solutions

    CERN Document Server

    Bahcall, J N; Peña-Garay, C; Bahcall, John N.; Peña-Garay, Carlos

    2002-01-01

    With the goal of identifying signatures that select specific neutrino oscillation parameters, we test the robustness of global oscillation solutions that fit all the available solar and reactor experimental data. We use three global analysis strategies previously applied by different authors and also determine the sensitivity of the oscillation solutions to the critical nuclear fusion cross section, S_{17}(0), for the production of 8B. The neutral current to charged current ratio for SNO is predicted to be 3.5 +- 0.6 (1 sigma) for the favored LMA, LOW, and VAC solutions, which is separated from the no-oscillation value of 1.0 by much more than the expected experimental error. The predicted range of the day-night difference in charged current rates is between 0% and 21% (3 sigma) and is to be strongly correlated with the day-night effect for neutrino-electron scattering. A measurement by SNO of either a NC to CC ratio > 3.3 or a day-night difference > 10%, would favor a small region of the currently allowed LM...

  18. Robust recognition via information theoretic learning

    CERN Document Server

    He, Ran; Yuan, Xiaotong; Wang, Liang

    2014-01-01

    This Springer Brief represents a comprehensive review of information theoretic methods for robust recognition. A variety of information theoretic methods have been proffered in the past decade, in a large variety of computer vision applications; this work brings them together, attempts to impart the theory, optimization and usage of information entropy.The?authors?resort to a new information theoretic concept, correntropy, as a robust measure and apply it to solve robust face recognition and object recognition problems. For computational efficiency,?the brief?introduces the additive and multip

  19. Robust statistics and geochemical data analysis

    International Nuclear Information System (INIS)

    Di, Z.

    1987-01-01

    Advantages of robust procedures over ordinary least-squares procedures in geochemical data analysis is demonstrated using NURE data from the Hot Springs Quadrangle, South Dakota, USA. Robust principal components analysis with 5% multivariate trimming successfully guarded the analysis against perturbations by outliers and increased the number of interpretable factors. Regression with SINE estimates significantly increased the goodness-of-fit of the regression and improved the correspondence of delineated anomalies with known uranium prospects. Because of the ubiquitous existence of outliers in geochemical data, robust statistical procedures are suggested as routine procedures to replace ordinary least-squares procedures

  20. Design Robust Controller for Rotary Kiln

    Directory of Open Access Journals (Sweden)

    Omar D. Hernández-Arboleda

    2013-11-01

    Full Text Available This paper presents the design of a robust controller for a rotary kiln. The designed controller is a combination of a fractional PID and linear quadratic regulator (LQR, these are not used to control the kiln until now, in addition robustness criteria are evaluated (gain margin, phase margin, strength gain, rejecting high frequency noise and sensitivity applied to the entire model (controller-plant, obtaining good results with a frequency range of 0.020 to 90 rad/s, which contributes to the robustness of the system.

  1. Towards distortion-free robust image authentication

    International Nuclear Information System (INIS)

    Coltuc, D

    2007-01-01

    This paper investigates a general framework for distortion-free robust image authentication by multiple marking. First, by robust watermarking a subsampled version of image edges is embedded. Then, by reversible watermarking the information needed to recover the original image is inserted, too. The hiding capacity of the reversible watermarking is the essential requirement for this approach. Thus in case of no attacks not only image is authenticated but also the original is exactly recovered. In case of attacks, reversibility is lost, but image can still be authenticated. Preliminary results providing very good robustness against JPEG compression are presented

  2. An Overview of the Adaptive Robust DFT

    Directory of Open Access Journals (Sweden)

    Djurović Igor

    2010-01-01

    Full Text Available Abstract This paper overviews basic principles and applications of the robust DFT (RDFT approach, which is used for robust processing of frequency-modulated (FM signals embedded in non-Gaussian heavy-tailed noise. In particular, we concentrate on the spectral analysis and filtering of signals corrupted by impulsive distortions using adaptive and nonadaptive robust estimators. Several adaptive estimators of location parameter are considered, and it is shown that their application is preferable with respect to non-adaptive counterparts. This fact is demonstrated by efficiency comparison of adaptive and nonadaptive RDFT methods for different noise environments.

  3. A robust interpretation of duration calculus

    DEFF Research Database (Denmark)

    Franzle, M.; Hansen, Michael Reichhardt

    2005-01-01

    We transfer the concept of robust interpretation from arithmetic first-order theories to metric-time temporal logics. The idea is that the interpretation of a formula is robust iff its truth value does not change under small variation of the constants in the formula. Exemplifying this on Duration...... Calculus (DC), our findings are that the robust interpretation of DC is equivalent to a multi-valued interpretation that uses the real numbers as semantic domain and assigns Lipschitz-continuous interpretations to all operators of DC. Furthermore, this continuity permits approximation between discrete...

  4. REINA at CLEF 2007 Robust Task

    OpenAIRE

    Zazo Rodríguez, Ángel Francisco; Figuerola, Carlos G.; Alonso Berrocal, José Luis

    2007-01-01

    This paper describes our work at CLEF 2007 Robust Task. We have participated in the monolingual (English, French and Portuguese) and the bilingual (English to French) subtask. At CLEF 2006 our research group obtained very good results applying local query expansion using windows of terms in the robust task. This year we have used the same expansion technique, but taking into account some criteria of robustness: MAP, GMAP, MMR, GS@10, P@10, number of failed topics, number of topics bellow 0.1 ...

  5. REINA at CLEF 2007 Robust Track (2007)

    OpenAIRE

    Zazo, Ángel F.; G.-Figuerola, Carlos; Alonso-Berrocal, José-Luis

    2007-01-01

    This paper describes our work at CLEF 2007 Robust Task. We have participated in the monolingual (English, French and Portuguese) and the bilingual (English to French) subtask. At CLEF 2006 our research group obtained very good results applying local query expansion using windows of terms in the robust task. This year we have used the same expansion technique, but taking into account some criteria of robustness: MAP, GMAP, MMR, GS@10, P@10, number of failed topics, number of topics bellow 0.1 ...

  6. Danish Requirements for Robustness of Structures

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Christensen, H. H.

    2006-01-01

    . This paper describes the background of the revised robustness requirements implemented in the Danish Code of Practice for Safety of Structures in 2003 [1, 2, 3]. According to the Danish design rules robustness shall be documented for all structures where consequences of failure are serious. This paper...... describes the background of the design procedure in the Danish codes, which shall be followed in order to document sufficient robustness in the following steps: Step 1: review of loads and possible failure modes/scenarios and determination of acceptable collapse extent. Step 2: review of the structural...

  7. Robustness-related issues in speaker recognition

    CERN Document Server

    Zheng, Thomas Fang

    2017-01-01

    This book presents an overview of speaker recognition technologies with an emphasis on dealing with robustness issues. Firstly, the book gives an overview of speaker recognition, such as the basic system framework, categories under different criteria, performance evaluation and its development history. Secondly, with regard to robustness issues, the book presents three categories, including environment-related issues, speaker-related issues and application-oriented issues. For each category, the book describes the current hot topics, existing technologies, and potential research focuses in the future. The book is a useful reference book and self-learning guide for early researchers working in the field of robust speech recognition.

  8. Robustness and structure of complex networks

    Science.gov (United States)

    Shao, Shuai

    This dissertation covers the two major parts of my PhD research on statistical physics and complex networks: i) modeling a new type of attack -- localized attack, and investigating robustness of complex networks under this type of attack; ii) discovering the clustering structure in complex networks and its influence on the robustness of coupled networks. Complex networks appear in every aspect of our daily life and are widely studied in Physics, Mathematics, Biology, and Computer Science. One important property of complex networks is their robustness under attacks, which depends crucially on the nature of attacks and the structure of the networks themselves. Previous studies have focused on two types of attack: random attack and targeted attack, which, however, are insufficient to describe many real-world damages. Here we propose a new type of attack -- localized attack, and study the robustness of complex networks under this type of attack, both analytically and via simulation. On the other hand, we also study the clustering structure in the network, and its influence on the robustness of a complex network system. In the first part, we propose a theoretical framework to study the robustness of complex networks under localized attack based on percolation theory and generating function method. We investigate the percolation properties, including the critical threshold of the phase transition pc and the size of the giant component Pinfinity. We compare localized attack with random attack and find that while random regular (RR) networks are more robust against localized attack, Erdoḧs-Renyi (ER) networks are equally robust under both types of attacks. As for scale-free (SF) networks, their robustness depends crucially on the degree exponent lambda. The simulation results show perfect agreement with theoretical predictions. We also test our model on two real-world networks: a peer-to-peer computer network and an airline network, and find that the real-world networks

  9. Robust Structured Control Design via LMI Optimization

    DEFF Research Database (Denmark)

    Adegas, Fabiano Daher; Stoustrup, Jakob

    2011-01-01

    This paper presents a new procedure for discrete-time robust structured control design. Parameter-dependent nonconvex conditions for stabilizable and induced L2-norm performance controllers are solved by an iterative linear matrix inequalities (LMI) optimization. A wide class of controller...... structures including decentralized of any order, fixed-order dynamic output feedback, static output feedback can be designed robust to polytopic uncertainties. Stability is proven by a parameter-dependent Lyapunov function. Numerical examples on robust stability margins shows that the proposed procedure can...

  10. Robust data reconciliation with TEMPO

    International Nuclear Information System (INIS)

    Sunde, Svein; Banati, Jozsef

    2004-03-01

    The Halden Project's TEMPO system is devised to meet the increasing challenges facing utilities in performance monitoring and optimisation, among other things due to deregulation and market liberalisation. The data reconciliation mode is an important one in the TEMPO system. Data reconciliation is a method to provide reliable estimates of process states, parameters, the state of equipment and instruments, and efficiency. Data reconciliation follows maximum likelihood principles, and is usually based on a Gaussian error model for the data. Data reconciliation thus estimates the most likely state of the process, given the heat and mass balance and the current instrument readings. If the assumption of normally (Gaussian) distributed errors in the measurements break down, as it will in the case of gross errors (outliers) in the data set, this needs to be detected by the monitoring system. TEMPO does this by computing an overall test statistic subjected to a hypothesis test, resulting in the so-called goodness-of-fit. If the goodness-of-fit takes a too low value, a fault is probably present in the process. Identifying the location of the fault is more difficult, however. With the Gaussian error model this is still possible employing a so-called serial elimination method. The serial elimination method is, however, cumbersome to use and leads to quite lengthy calculations. The present report describes the application of alternative distributions in the maximum likelihood estimation in an attempt to directly identify the location of faulty sensors. For direct identification of sensor faults significant improvements over the method based on a Gaussian error model has been achieved. However, serial elimination still leads to the highest success rate for fault identification. All results were based on Monte Carlo simulations. (Author)

  11. Problems Identifying Independent and Dependent Variables

    Science.gov (United States)

    Leatham, Keith R.

    2012-01-01

    This paper discusses one step from the scientific method--that of identifying independent and dependent variables--from both scientific and mathematical perspectives. It begins by analyzing an episode from a middle school mathematics classroom that illustrates the need for students and teachers alike to develop a robust understanding of…

  12. Histone Variant HTZ1 Shows Extensive Epistasis with, but Does Not Increase Robustness to, New Mutations

    Science.gov (United States)

    Richardson, Joshua B.; Uppendahl, Locke D.; Traficante, Maria K.; Levy, Sasha F.; Siegal, Mark L.

    2013-01-01

    Biological systems produce phenotypes that appear to be robust to perturbation by mutations and environmental variation. Prior studies identified genes that, when impaired, reveal previously cryptic genetic variation. This result is typically interpreted as evidence that the disrupted gene normally increases robustness to mutations, as such robustness would allow cryptic variants to accumulate. However, revelation of cryptic genetic variation is not necessarily evidence that a mutationally robust state has been made less robust. Demonstrating a difference in robustness requires comparing the ability of each state (with the gene perturbed or intact) to suppress the effects of new mutations. Previous studies used strains in which the existing genetic variation had been filtered by selection. Here, we use mutation accumulation (MA) lines that have experienced minimal selection, to test the ability of histone H2A.Z (HTZ1) to increase robustness to mutations in the yeast Saccharomyces cerevisiae. HTZ1, a regulator of chromatin structure and gene expression, represents a class of genes implicated in mutational robustness. It had previously been shown to increase robustness of yeast cell morphology to fluctuations in the external or internal microenvironment. We measured morphological variation within and among 79 MA lines with and without HTZ1. Analysis of within-line variation confirms that HTZ1 increases microenvironmental robustness. Analysis of between-line variation shows the morphological effects of eliminating HTZ1 to be highly dependent on the line, which implies that HTZ1 interacts with mutations that have accumulated in the lines. However, lines without HTZ1 are, as a group, not more phenotypically diverse than lines with HTZ1 present. The presence of HTZ1, therefore, does not confer greater robustness to mutations than its absence. Our results provide experimental evidence that revelation of cryptic genetic variation cannot be assumed to be caused by loss of

  13. Histone variant HTZ1 shows extensive epistasis with, but does not increase robustness to, new mutations.

    Directory of Open Access Journals (Sweden)

    Joshua B Richardson

    Full Text Available Biological systems produce phenotypes that appear to be robust to perturbation by mutations and environmental variation. Prior studies identified genes that, when impaired, reveal previously cryptic genetic variation. This result is typically interpreted as evidence that the disrupted gene normally increases robustness to mutations, as such robustness would allow cryptic variants to accumulate. However, revelation of cryptic genetic variation is not necessarily evidence that a mutationally robust state has been made less robust. Demonstrating a difference in robustness requires comparing the ability of each state (with the gene perturbed or intact to suppress the effects of new mutations. Previous studies used strains in which the existing genetic variation had been filtered by selection. Here, we use mutation accumulation (MA lines that have experienced minimal selection, to test the ability of histone H2A.Z (HTZ1 to increase robustness to mutations in the yeast Saccharomyces cerevisiae. HTZ1, a regulator of chromatin structure and gene expression, represents a class of genes implicated in mutational robustness. It had previously been shown to increase robustness of yeast cell morphology to fluctuations in the external or internal microenvironment. We measured morphological variation within and among 79 MA lines with and without HTZ1. Analysis of within-line variation confirms that HTZ1 increases microenvironmental robustness. Analysis of between-line variation shows the morphological effects of eliminating HTZ1 to be highly dependent on the line, which implies that HTZ1 interacts with mutations that have accumulated in the lines. However, lines without HTZ1 are, as a group, not more phenotypically diverse than lines with HTZ1 present. The presence of HTZ1, therefore, does not confer greater robustness to mutations than its absence. Our results provide experimental evidence that revelation of cryptic genetic variation cannot be assumed to be

  14. Robust synthesis for real-time systems

    DEFF Research Database (Denmark)

    Larsen, Kim Guldstrand; Legay, Axel; Traonouez, Luois-Marie

    2014-01-01

    Specification theories for real-time systems allow reasoning about interfaces and their implementation models, using a set of operators that includes satisfaction, refinement, logical and parallel composition. To make such theories applicable throughout the entire design process from an abstract...... of introducing small perturbations into formal models. We address this problem of robust implementations in timed specification theories. We first consider a fixed perturbation and study the robustness of timed specifications with respect to the operators of the theory. To this end we synthesize robust...... specification to an implementation, we need to reason about the possibility to effectively implement the theoretical specifications on physical systems, despite their limited precision. In the literature, this implementation problem has been linked to the robustness problem that analyzes the consequences...

  15. Robust adaptive synchronization of general dynamical networks ...

    Indian Academy of Sciences (India)

    Robust adaptive synchronization; dynamical network; multiple delays; multiple uncertainties. ... Networks such as neural networks, communication transmission networks, social rela- tionship networks etc. ..... a very good effect. Pramana – J.

  16. Technical Challenges Hindering Development of Robust Wireless ...

    African Journals Online (AJOL)

    PROF. OLIVER OSUAGWA

    2015-12-01

    Dec 1, 2015 ... challenges remain to be resolved, in designing robust wireless networks that can deliver the performance ... demonstrated the first radio transmission from the Isle of ... distances with better quality, less power, and smaller ...

  17. Multifidelity Robust Aeroelastic Design, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Nielsen Engineering & Research (NEAR) proposes a new method to generate mathematical models of wind-tunnel models and flight vehicles for robust aeroelastic...

  18. The structural robustness of multiprocessor computing system

    Directory of Open Access Journals (Sweden)

    N. Andronaty

    1996-03-01

    Full Text Available The model of the multiprocessor computing system on the base of transputers which permits to resolve the question of valuation of a structural robustness (viability, survivability is described.

  19. Robust and Efficient Parametric Face Alignment

    NARCIS (Netherlands)

    Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja

    2011-01-01

    We propose a correlation-based approach to parametric object alignment particularly suitable for face analysis applications which require efficiency and robustness against occlusions and illumination changes. Our algorithm registers two images by iteratively maximizing their correlation coefficient

  20. Framework for Robustness Assessment of Timber Structures

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2011-01-01

    This paper presents a theoretical framework for the design and analysis of robustness of timber structures. This is actualized by a more4 frequent use of advanced types of timber structures with limited redundancy and serious consequences in the case of failure. Combined with increased requirements...... to efficiency in design and execution followed by increased risk of human errors has made the need of requirements to robustness of new structures essential. Further, the collapse of the Ballerup Super Arena, the bad Reichenhall Ice-Arena and a number of other structural systems during the last 10 years has...... increased the interest in robustness. Typically, modern structural design codes require that ‘the consequence of damages to structures should not be disproportional to the causes of the damages’. However, although the importance of robustness for structural design is widely recognized, the code requirements...

  1. Robust Analysis and Design of Multivariable Systems

    National Research Council Canada - National Science Library

    Tannenbaum, Allen

    1998-01-01

    In this Final Report, we will describe the work we have performed in robust control theory and nonlinear control, and the utilization of techniques in image processing and computer vision for problems in visual tracking...

  2. Robust Tracking Control for a Piezoelectric Actuator

    National Research Council Canada - National Science Library

    Salah, M; McIntyre, M; Dawson, D; Wagner, J

    2006-01-01

    In this paper, a hysteresis model-based nonlinear robust controller is developed for a piezoelectric actuator, utilizing a Lyapunov-based stability analysis, which ensures that a desired displacement...

  3. Robustness studies on coal gasification process variables

    African Journals Online (AJOL)

    coal before feeding to the gasification process [1]. .... to-control variables will make up the terms in the response surface model for the ... Montgomery (1999) explained that all the Taguchi engineering objectives for a robust ..... software [3].

  4. Antecedents and Dimensions of Supply Chain Robustness

    OpenAIRE

    Durach, Christian F.; Wieland, Andreas; Machuca, Jose A.D.

    2015-01-01

    Purpose – The purpose of this paper is to provide groundwork for an emerging theory of supply chain robustness – which has been conceptualized as a dimension of supply chain resilience – through reviewing and synthesizing related yet disconnected studies. The paper develops a formal definition of supply chain robustness to build a framework that captures the dimensions, antecedents and moderators of the construct as discussed in the literature. Design/methodology/approach – The...

  5. A Unifying Mathematical Framework for Genetic Robustness, Environmental Robustness, Network Robustness and their Trade-offs on Phenotype Robustness in Biological Networks. Part III: Synthetic Gene Networks in Synthetic Biology

    Science.gov (United States)

    Chen, Bor-Sen; Lin, Ying-Po

    2013-01-01

    Robust stabilization and environmental disturbance attenuation are ubiquitous systematic properties that are observed in biological systems at many different levels. The underlying principles for robust stabilization and environmental disturbance attenuation are universal to both complex biological systems and sophisticated engineering systems. In many biological networks, network robustness should be large enough to confer: intrinsic robustness for tolerating intrinsic parameter fluctuations; genetic robustness for buffering genetic variations; and environmental robustness for resisting environmental disturbances. Network robustness is needed so phenotype stability of biological network can be maintained, guaranteeing phenotype robustness. Synthetic biology is foreseen to have important applications in biotechnology and medicine; it is expected to contribute significantly to a better understanding of functioning of complex biological systems. This paper presents a unifying mathematical framework for investigating the principles of both robust stabilization and environmental disturbance attenuation for synthetic gene networks in synthetic biology. Further, from the unifying mathematical framework, we found that the phenotype robustness criterion for synthetic gene networks is the following: if intrinsic robustness + genetic robustness + environmental robustness ≦ network robustness, then the phenotype robustness can be maintained in spite of intrinsic parameter fluctuations, genetic variations, and environmental disturbances. Therefore, the trade-offs between intrinsic robustness, genetic robustness, environmental robustness, and network robustness in synthetic biology can also be investigated through corresponding phenotype robustness criteria from the systematic point of view. Finally, a robust synthetic design that involves network evolution algorithms with desired behavior under intrinsic parameter fluctuations, genetic variations, and environmental

  6. Robust simultaneous detection of coronary borders in complex images

    International Nuclear Information System (INIS)

    Sonka, M.; Winniford, M.D.; Collins, S.M.

    1995-01-01

    Visual estimation of coronary obstruction severity from angiograms suffers from poor inter- and intraobserver reproducibility and is often inaccurate. In spite of the widely recognized limitations of visual analysis, automated methods have not found widespread clinical use, in part because they too frequently fail to accurately identify vessel borders. The authors have developed a robust method for simultaneous detection of left and right coronary borders that is suitable for analysis of complex images with poor contrast, nearby or overlapping structures, or branching vessels. The reliability of the simultaneous border detection method and that of their previously reported conventional border detection method were tested in 130 complex images, selected because conventional automated border detection might be expected to fail. Conventional analysis failed to yield acceptable borders in 65/130 or 50% of images. Simultaneous border detection was much more robust (p < .001) and failed in only 15/130 or 12% of complex images. Simultaneous border detection identified stenosis diameters that correlated significantly better with observer-derived stenosis diameters than did diameters obtained with conventional border detection (p < 0.001). Simultaneous detection of left and right coronary borders is highly robust and has substantial promise for enhancing the utility of quantitative coronary angiography in the clinical setting

  7. Adaptive Critic Nonlinear Robust Control: A Survey.

    Science.gov (United States)

    Wang, Ding; He, Haibo; Liu, Derong

    2017-10-01

    Adaptive dynamic programming (ADP) and reinforcement learning are quite relevant to each other when performing intelligent optimization. They are both regarded as promising methods involving important components of evaluation and improvement, at the background of information technology, such as artificial intelligence, big data, and deep learning. Although great progresses have been achieved and surveyed when addressing nonlinear optimal control problems, the research on robustness of ADP-based control strategies under uncertain environment has not been fully summarized. Hence, this survey reviews the recent main results of adaptive-critic-based robust control design of continuous-time nonlinear systems. The ADP-based nonlinear optimal regulation is reviewed, followed by robust stabilization of nonlinear systems with matched uncertainties, guaranteed cost control design of unmatched plants, and decentralized stabilization of interconnected systems. Additionally, further comprehensive discussions are presented, including event-based robust control design, improvement of the critic learning rule, nonlinear H ∞ control design, and several notes on future perspectives. By applying the ADP-based optimal and robust control methods to a practical power system and an overhead crane plant, two typical examples are provided to verify the effectiveness of theoretical results. Overall, this survey is beneficial to promote the development of adaptive critic control methods with robustness guarantee and the construction of higher level intelligent systems.

  8. Sequence robust association test for familial data.

    Science.gov (United States)

    Dai, Wei; Yang, Ming; Wang, Chaolong; Cai, Tianxi

    2017-09-01

    Genome-wide association studies (GWAS) and next generation sequencing studies (NGSS) are often performed in family studies to improve power in identifying genetic variants that are associated with clinical phenotypes. Efficient analysis of genome-wide studies with familial data is challenging due to the difficulty in modeling shared but unmeasured genetic and/or environmental factors that cause dependencies among family members. Existing genetic association testing procedures for family studies largely rely on generalized estimating equations (GEE) or linear mixed-effects (LME) models. These procedures may fail to properly control for type I errors when the imposed model assumptions fail. In this article, we propose the Sequence Robust Association Test (SRAT), a fully rank-based, flexible approach that tests for association between a set of genetic variants and an outcome, while accounting for within-family correlation and adjusting for covariates. Comparing to existing methods, SRAT has the advantages of allowing for unknown correlation structures and weaker assumptions about the outcome distribution. We provide theoretical justifications for SRAT and show that SRAT includes the well-known Wilcoxon rank sum test as a special case. Extensive simulation studies suggest that SRAT provides better protection against type I error rate inflation, and could be much more powerful for settings with skewed outcome distribution than existing methods. For illustration, we also apply SRAT to the familial data from the Framingham Heart Study and Offspring Study to examine the association between an inflammatory marker and a few sets of genetic variants. © 2017, The International Biometric Society.

  9. Model Based Autonomy for Robust Mars Operations

    Science.gov (United States)

    Kurien, James A.; Nayak, P. Pandurang; Williams, Brian C.; Lau, Sonie (Technical Monitor)

    1998-01-01

    Space missions have historically relied upon a large ground staff, numbering in the hundreds for complex missions, to maintain routine operations. When an anomaly occurs, this small army of engineers attempts to identify and work around the problem. A piloted Mars mission, with its multiyear duration, cost pressures, half-hour communication delays and two-week blackouts cannot be closely controlled by a battalion of engineers on Earth. Flight crew involvement in routine system operations must also be minimized to maximize science return. It also may be unrealistic to require the crew have the expertise in each mission subsystem needed to diagnose a system failure and effect a timely repair, as engineers did for Apollo 13. Enter model-based autonomy, which allows complex systems to autonomously maintain operation despite failures or anomalous conditions, contributing to safe, robust, and minimally supervised operation of spacecraft, life support, In Situ Resource Utilization (ISRU) and power systems. Autonomous reasoning is central to the approach. A reasoning algorithm uses a logical or mathematical model of a system to infer how to operate the system, diagnose failures and generate appropriate behavior to repair or reconfigure the system in response. The 'plug and play' nature of the models enables low cost development of autonomy for multiple platforms. Declarative, reusable models capture relevant aspects of the behavior of simple devices (e.g. valves or thrusters). Reasoning algorithms combine device models to create a model of the system-wide interactions and behavior of a complex, unique artifact such as a spacecraft. Rather than requiring engineers to all possible interactions and failures at design time or perform analysis during the mission, the reasoning engine generates the appropriate response to the current situation, taking into account its system-wide knowledge, the current state, and even sensor failures or unexpected behavior.

  10. QUALITY IMPROVEMENT IN MULTIRESPONSE EXPERIMENTS THROUGH ROBUST DESIGN METHODOLOGY

    Directory of Open Access Journals (Sweden)

    M. Shilpa

    2012-06-01

    Full Text Available Robust design methodology aims at reducing the variability in the product performance in the presence of noise factors. Experiments involving simultaneous optimization of more than one quality characteristic are known as multiresponse experiments which are used in the development and improvement of industrial processes and products. In this paper, robust design methodology is applied to optimize the process parameters during a particular operation of rotary driving shaft manufacturing process. The three important quality characteristics of the shaft considered here are of type Nominal-the-best, Smaller-the-better and Fraction defective. Simultaneous optimization of these responses is carried out by identifying the control parameters and conducting the experimentation using L9 orthogonal array.

  11. Robustness of the ATLAS pixel clustering neural network algorithm

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00407780; The ATLAS collaboration

    2016-01-01

    Proton-proton collisions at the energy frontier puts strong constraints on track reconstruction algorithms. The algorithms depend heavily on accurate estimation of the position of particles as they traverse the inner detector elements. An artificial neural network algorithm is utilised to identify and split clusters of neighbouring read-out elements in the ATLAS pixel detector created by multiple charged particles. The method recovers otherwise lost tracks in dense environments where particles are separated by distances comparable to the size of the detector read-out elements. Such environments are highly relevant for LHC run 2, e.g. in searches for heavy resonances. Within the scope of run 2 track reconstruction performance and upgrades, the robustness of the neural network algorithm will be presented. The robustness has been studied by evaluating the stability of the algorithm’s performance under a range of variations in the pixel detector conditions.

  12. Robustness in NAA evaluated by the Youden and Steiner test

    International Nuclear Information System (INIS)

    Bedregal, P.; Torres, B.; Ubillus, M.; Mendoza, P.; Montoya, E.

    2008-01-01

    The chemistry laboratory at the Peruvian Institute of Nuclear Energy (IPEN) has carried out a validation method for the samples of siliceous composition. At least seven variables affecting the robustness of the results were initially identified, which may interact simultaneously or individually. Conventional evaluation hereof would imply a massive number of analyses and a far more effective approach for assessment of the robustness for these effects was found in the Youden-Steiner test, which provides the necessary information by only eight analyses for each sample type. Three reference materials were used for evaluating the effects of variations in sample mass, irradiation duration, standard mass, neutron flux, decay time, counting time and counting distance. (author)

  13. Measure of robustness for complex networks

    Science.gov (United States)

    Youssef, Mina Nabil

    Critical infrastructures are repeatedly attacked by external triggers causing tremendous amount of damages. Any infrastructure can be studied using the powerful theory of complex networks. A complex network is composed of extremely large number of different elements that exchange commodities providing significant services. The main functions of complex networks can be damaged by different types of attacks and failures that degrade the network performance. These attacks and failures are considered as disturbing dynamics, such as the spread of viruses in computer networks, the spread of epidemics in social networks, and the cascading failures in power grids. Depending on the network structure and the attack strength, every network differently suffers damages and performance degradation. Hence, quantifying the robustness of complex networks becomes an essential task. In this dissertation, new metrics are introduced to measure the robustness of technological and social networks with respect to the spread of epidemics, and the robustness of power grids with respect to cascading failures. First, we introduce a new metric called the Viral Conductance (VCSIS ) to assess the robustness of networks with respect to the spread of epidemics that are modeled through the susceptible/infected/susceptible (SIS) epidemic approach. In contrast to assessing the robustness of networks based on a classical metric, the epidemic threshold, the new metric integrates the fraction of infected nodes at steady state for all possible effective infection strengths. Through examples, VCSIS provides more insights about the robustness of networks than the epidemic threshold. In addition, both the paradoxical robustness of Barabasi-Albert preferential attachment networks and the effect of the topology on the steady state infection are studied, to show the importance of quantifying the robustness of networks. Second, a new metric VCSIR is introduced to assess the robustness of networks with respect

  14. A Comparative Theoretical and Computational Study on Robust Counterpart Optimization: I. Robust Linear Optimization and Robust Mixed Integer Linear Optimization

    Science.gov (United States)

    Li, Zukui; Ding, Ran; Floudas, Christodoulos A.

    2011-01-01

    Robust counterpart optimization techniques for linear optimization and mixed integer linear optimization problems are studied in this paper. Different uncertainty sets, including those studied in literature (i.e., interval set; combined interval and ellipsoidal set; combined interval and polyhedral set) and new ones (i.e., adjustable box; pure ellipsoidal; pure polyhedral; combined interval, ellipsoidal, and polyhedral set) are studied in this work and their geometric relationship is discussed. For uncertainty in the left hand side, right hand side, and objective function of the optimization problems, robust counterpart optimization formulations induced by those different uncertainty sets are derived. Numerical studies are performed to compare the solutions of the robust counterpart optimization models and applications in refinery production planning and batch process scheduling problem are presented. PMID:21935263

  15. Identifying Robust Co-Occurrence Patterns in Personal Care Product Purchases

    Science.gov (United States)

    Personal care products (PCPs) are used for beautification and personal hygiene, and because they are applied to the skin, hair, and mouth, they provide an efficient delivery vehicle for chemicals into our bodies. Although efforts have been made to enumerate the chemicals in indiv...

  16. Application of the network robustness index to identify critical links supporting Vermont's Bulk milk transportation.

    Science.gov (United States)

    2011-08-18

    The food supply chain is an interwoven network consisting of producers, processors, : manufacturers, distributors, retailers, and consumers. With the exception of direct : marketing or community-supported agriculture systems, some or all of these int...

  17. Identifying multiple outliers in linear regression: robust fit and clustering approach

    International Nuclear Information System (INIS)

    Robiah Adnan; Mohd Nor Mohamad; Halim Setan

    2001-01-01

    This research provides a clustering based approach for determining potential candidates for outliers. This is modification of the method proposed by Serbert et. al (1988). It is based on using the single linkage clustering algorithm to group the standardized predicted and residual values of data set fit by least trimmed of squares (LTS). (Author)

  18. Robustness analysis of chiller sequencing control

    International Nuclear Information System (INIS)

    Liao, Yundan; Sun, Yongjun; Huang, Gongsheng

    2015-01-01

    Highlights: • Uncertainties with chiller sequencing control were systematically quantified. • Robustness of chiller sequencing control was systematically analyzed. • Different sequencing control strategies were sensitive to different uncertainties. • A numerical method was developed for easy selection of chiller sequencing control. - Abstract: Multiple-chiller plant is commonly employed in the heating, ventilating and air-conditioning system to increase operational feasibility and energy-efficiency under part load condition. In a multiple-chiller plant, chiller sequencing control plays a key role in achieving overall energy efficiency while not sacrifices the cooling sufficiency for indoor thermal comfort. Various sequencing control strategies have been developed and implemented in practice. Based on the observation that (i) uncertainty, which cannot be avoided in chiller sequencing control, has a significant impact on the control performance and may cause the control fail to achieve the expected control and/or energy performance; and (ii) in current literature few studies have systematically addressed this issue, this paper therefore presents a study on robustness analysis of chiller sequencing control in order to understand the robustness of various chiller sequencing control strategies under different types of uncertainty. Based on the robustness analysis, a simple and applicable method is developed to select the most robust control strategy for a given chiller plant in the presence of uncertainties, which will be verified using case studies

  19. Information theory perspective on network robustness

    International Nuclear Information System (INIS)

    Schieber, Tiago A.; Carpi, Laura; Frery, Alejandro C.; Rosso, Osvaldo A.; Pardalos, Panos M.; Ravetti, Martín G.

    2016-01-01

    A crucial challenge in network theory is the study of the robustness of a network when facing a sequence of failures. In this work, we propose a dynamical definition of network robustness based on Information Theory, that considers measurements of the structural changes caused by failures of the network's components. Failures are defined here as a temporal process defined in a sequence. Robustness is then evaluated by measuring dissimilarities between topologies after each time step of the sequence, providing a dynamical information about the topological damage. We thoroughly analyze the efficiency of the method in capturing small perturbations by considering different probability distributions on networks. In particular, we find that distributions based on distances are more consistent in capturing network structural deviations, as better reflect the consequences of the failures. Theoretical examples and real networks are used to study the performance of this methodology. - Highlights: • A novel methodology to measure the robustness of a network to component failure or targeted attacks is proposed. • The use of the network's distance PDF allows a precise analysis. • The method provides a dynamic robustness profile showing the response of the topology to each failure event. • The measure is capable to detect network's critical elements.

  20. On the robustness of Herlihy's hierarchy

    Science.gov (United States)

    Jayanti, Prasad

    1993-01-01

    A wait-free hierarchy maps object types to levels in Z(+) U (infinity) and has the following property: if a type T is at level N, and T' is an arbitrary type, then there is a wait-free implementation of an object of type T', for N processes, using only registers and objects of type T. The infinite hierarchy defined by Herlihy is an example of a wait-free hierarchy. A wait-free hierarchy is robust if it has the following property: if T is at level N, and S is a finite set of types belonging to levels N - 1 or lower, then there is no wait-free implementation of an object of type T, for N processes, using any number and any combination of objects belonging to the types in S. Robustness implies that there are no clever ways of combining weak shared objects to obtain stronger ones. Contrary to what many researchers believe, we prove that Herlihy's hierarchy is not robust. We then define some natural variants of Herlihy's hierarchy, which are also infinite wait-free hierarchies. With the exception of one, which is still open, these are not robust either. We conclude with the open question of whether non-trivial robust wait-free hierarchies exist.

  1. Replication and robustness in developmental research.

    Science.gov (United States)

    Duncan, Greg J; Engel, Mimi; Claessens, Amy; Dowsett, Chantelle J

    2014-11-01

    Replications and robustness checks are key elements of the scientific method and a staple in many disciplines. However, leading journals in developmental psychology rarely include explicit replications of prior research conducted by different investigators, and few require authors to establish in their articles or online appendices that their key results are robust across estimation methods, data sets, and demographic subgroups. This article makes the case for prioritizing both explicit replications and, especially, within-study robustness checks in developmental psychology. It provides evidence on variation in effect sizes in developmental studies and documents strikingly different replication and robustness-checking practices in a sample of journals in developmental psychology and a sister behavioral science-applied economics. Our goal is not to show that any one behavioral science has a monopoly on best practices, but rather to show how journals from a related discipline address vital concerns of replication and generalizability shared by all social and behavioral sciences. We provide recommendations for promoting graduate training in replication and robustness-checking methods and for editorial policies that encourage these practices. Although some of our recommendations may shift the form and substance of developmental research articles, we argue that they would generate considerable scientific benefits for the field. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

  2. Primal and dual approaches to adjustable robust optimization

    NARCIS (Netherlands)

    de Ruiter, Frans

    2018-01-01

    Robust optimization has become an important paradigm to deal with optimization under uncertainty. Adjustable robust optimization is an extension that deals with multistage problems. This thesis starts with a short but comprehensive introduction to adjustable robust optimization. Then the two

  3. Robust Object Tracking Using Valid Fragments Selection.

    Science.gov (United States)

    Zheng, Jin; Li, Bo; Tian, Peng; Luo, Gang

    Local features are widely used in visual tracking to improve robustness in cases of partial occlusion, deformation and rotation. This paper proposes a local fragment-based object tracking algorithm. Unlike many existing fragment-based algorithms that allocate the weights to each fragment, this method firstly defines discrimination and uniqueness for local fragment, and builds an automatic pre-selection of useful fragments for tracking. Then, a Harris-SIFT filter is used to choose the current valid fragments, excluding occluded or highly deformed fragments. Based on those valid fragments, fragment-based color histogram provides a structured and effective description for the object. Finally, the object is tracked using a valid fragment template combining the displacement constraint and similarity of each valid fragment. The object template is updated by fusing feature similarity and valid fragments, which is scale-adaptive and robust to partial occlusion. The experimental results show that the proposed algorithm is accurate and robust in challenging scenarios.

  4. Occupant behaviour and robustness of building design

    DEFF Research Database (Denmark)

    Buso, Tiziana; Fabi, Valentina; Andersen, Rune Korsholm

    2015-01-01

    in a dynamic building energy simulation tool (IDA ICE). The analysis was carried out by simulating 15 building envelope designs in different thermal zones of an Office Reference Building in 3 climates: Stockholm, Frankfurt and Athens.In general, robustness towards changes in occupants' behaviour increased......Occupant behaviour can cause major discrepancies between the designed and the real total energy use in buildings. A possible solution to reduce the differences between predictions and actual performances is designing robust buildings, i.e. buildings whose performances show little variations...... with alternating occupant behaviour patterns. The aim of this work was to investigate how alternating occupant behaviour patterns impact the performance of different envelope design solutions in terms of building robustness. Probabilistic models of occupants' window opening and use of shading were implemented...

  5. Robust Mediation Analysis Based on Median Regression

    Science.gov (United States)

    Yuan, Ying; MacKinnon, David P.

    2014-01-01

    Mediation analysis has many applications in psychology and the social sciences. The most prevalent methods typically assume that the error distribution is normal and homoscedastic. However, this assumption may rarely be met in practice, which can affect the validity of the mediation analysis. To address this problem, we propose robust mediation analysis based on median regression. Our approach is robust to various departures from the assumption of homoscedasticity and normality, including heavy-tailed, skewed, contaminated, and heteroscedastic distributions. Simulation studies show that under these circumstances, the proposed method is more efficient and powerful than standard mediation analysis. We further extend the proposed robust method to multilevel mediation analysis, and demonstrate through simulation studies that the new approach outperforms the standard multilevel mediation analysis. We illustrate the proposed method using data from a program designed to increase reemployment and enhance mental health of job seekers. PMID:24079925

  6. Robustness of Distance-to-Default

    DEFF Research Database (Denmark)

    Jessen, Cathrine; Lando, David

    2013-01-01

    Distance-to-default is a remarkably robust measure for ranking firms according to their risk of default. The ranking seems to work despite the fact that the Merton model from which the measure is derived produces default probabilities that are far too small when applied to real data. We use...... simulations to investigate the robustness of the distance-to-default measure to different model specifications. Overall we find distance-to-default to be robust to a number of deviations from the simple Merton model that involve different asset value dynamics and different default triggering mechanisms....... A notable exception is a model with stochastic volatility of assets. In this case both the ranking of firms and the estimated default probabilities using distance-to-default perform significantly worse. We therefore propose a volatility adjustment of the distance-to-default measure, that significantly...

  7. Robust Portfolio Optimization using CAPM Approach

    Directory of Open Access Journals (Sweden)

    mohsen gharakhani

    2013-08-01

    Full Text Available In this paper, a new robust model of multi-period portfolio problem has been developed. One of the key concerns in any asset allocation problem is how to cope with uncertainty about future returns. There are some approaches in the literature for this purpose including stochastic programming and robust optimization. Applying these techniques to multi-period portfolio problem may increase the problem size in a way that the resulting model is intractable. In this paper, a novel approach has been proposed to formulate multi-period portfolio problem as an uncertain linear program assuming that asset return follows the single-index factor model. Robust optimization technique has been also used to solve the problem. In order to evaluate the performance of the proposed model, a numerical example has been applied using simulated data.

  8. Robustness of quantum correlations against linear noise

    International Nuclear Information System (INIS)

    Guo, Zhihua; Cao, Huaixin; Qu, Shixian

    2016-01-01

    Relative robustness of quantum correlations (RRoQC) of a bipartite state is firstly introduced relative to a classically correlated state. Robustness of quantum correlations (RoQC) of a bipartite state is then defined as the minimum of RRoQC of the state relative to all classically correlated ones. It is proved that as a function on quantum states, RoQC is nonnegative, lower semi-continuous and neither convex nor concave; especially, it is zero if and only if the state is classically correlated. Thus, RoQC not only quantifies the endurance of quantum correlations of a state against linear noise, but also can be used to distinguish between quantum and classically correlated states. Furthermore, the effects of local quantum channels on the robustness are explored and characterized. (paper)

  9. Parametric uncertainty modeling for robust control

    DEFF Research Database (Denmark)

    Rasmussen, K.H.; Jørgensen, Sten Bay

    1999-01-01

    The dynamic behaviour of a non-linear process can often be approximated with a time-varying linear model. In the presented methodology the dynamics is modeled non-conservatively as parametric uncertainty in linear lime invariant models. The obtained uncertainty description makes it possible...... to perform robustness analysis on a control system using the structured singular value. The idea behind the proposed method is to fit a rational function to the parameter variation. The parameter variation can then be expressed as a linear fractional transformation (LFT), It is discussed how the proposed...... point changes. It is shown that a diagonal PI control structure provides robust performance towards variations in feed flow rate or feed concentrations. However including both liquid and vapor flow delays robust performance specifications cannot be satisfied with this simple diagonal control structure...

  10. Incentive-Compatible Robust Line Planning

    Science.gov (United States)

    Bessas, Apostolos; Kontogiannis, Spyros; Zaroliagis, Christos

    The problem of robust line planning requests for a set of origin-destination paths (lines) along with their frequencies in an underlying railway network infrastructure, which are robust to fluctuations of real-time parameters of the solution. In this work, we investigate a variant of robust line planning stemming from recent regulations in the railway sector that introduce competition and free railway markets, and set up a new application scenario: there is a (potentially large) number of line operators that have their lines fixed and operate as competing entities issuing frequency requests, while the management of the infrastructure itself remains the responsibility of a single entity, the network operator. The line operators are typically unwilling to reveal their true incentives, while the network operator strives to ensure a fair (or socially optimal) usage of the infrastructure, e.g., by maximizing the (unknown to him) aggregate incentives of the line operators.

  11. Origins of robustness in translational control via eukaryotic translation initiation factor (eIF) 2.

    Science.gov (United States)

    Khan, Mohammad Farhan; Spurgeon, Sarah; von der Haar, Tobias

    2018-05-14

    Phosphorylation of eukaryotic translation initiation factor 2 (eIF2) is one of the best studied and most widely used means for regulating protein synthesis activity in eukaryotic cells. This pathway regulates protein synthesis in response to stresses, viral infections, and nutrient depletion, among others. We present analyses of an ordinary differential equation-based model of this pathway, which aim to identify its principal robustness-conferring features. Our analyses indicate that robustness is a distributed property, rather than arising from the properties of any one individual pathway species. However, robustness-conferring properties are unevenly distributed between the different species, and we identify a guanine nucleotide dissociation inhibitor (GDI) complex as a species that likely contributes strongly to the robustness of the pathway. Our analyses make further predictions on the dynamic response to different types of kinases that impinge on eIF2. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Robustness from flexibility in the fungal circadian clock

    Directory of Open Access Journals (Sweden)

    Akman Ozgur E

    2010-06-01

    Full Text Available Abstract Background Robustness is a central property of living systems, enabling function to be maintained against environmental perturbations. A key challenge is to identify the structures in biological circuits that confer system-level properties such as robustness. Circadian clocks allow organisms to adapt to the predictable changes of the 24-hour day/night cycle by generating endogenous rhythms that can be entrained to the external cycle. In all organisms, the clock circuits typically comprise multiple interlocked feedback loops controlling the rhythmic expression of key genes. Previously, we showed that such architectures increase the flexibility of the clock's rhythmic behaviour. We now test the relationship between flexibility and robustness, using a mathematical model of the circuit controlling conidiation in the fungus Neurospora crassa. Results The circuit modelled in this work consists of a central negative feedback loop, in which the frequency (frq gene inhibits its transcriptional activator white collar-1 (wc-1, interlocked with a positive feedback loop in which FRQ protein upregulates WC-1 production. Importantly, our model reproduces the observed entrainment of this circuit under light/dark cycles with varying photoperiod and cycle duration. Our simulations show that whilst the level of frq mRNA is driven directly by the light input, the falling phase of FRQ protein, a molecular correlate of conidiation, maintains a constant phase that is uncoupled from the times of dawn and dusk. The model predicts the behaviour of mutants that uncouple WC-1 production from FRQ's positive feedback, and shows that the positive loop enhances the buffering of conidiation phase against seasonal photoperiod changes. This property is quantified using Kitano's measure for the overall robustness of a regulated system output. Further analysis demonstrates that this functional robustness is a consequence of the greater evolutionary flexibility conferred on

  13. Competition improves robustness against loss of information

    Directory of Open Access Journals (Sweden)

    Arash eKermani Kolankeh

    2015-03-01

    Full Text Available A substantial number of works aimed at modeling the receptive field properties of the primary visual cortex (V1. Their evaluation criterion is usually the similarity of the model response properties to the recorded responses from biological organisms. However, as several algorithms were able to demonstrate some degree of similarity to biological data based on the existing criteria, we focus on the robustness against loss of information in the form of occlusions as an additional constraint for better understanding the algorithmic level of early vision in the brain. We try to investigate the influence of competition mechanisms on the robustness. Therefore, we compared four methods employing different competition mechanisms, namely, independent component analysis, non-negative matrix factorization with sparseness constraint, predictive coding/biased competition, and a Hebbian neural network with lateral inhibitory connections. Each of those methods is known to be capable of developing receptive fields comparable to those of V1 simple-cells. Since measuring the robustness of methods having simple-cell like receptive fields against occlusion is difficult, we measure the robustness using the classification accuracy on the MNIST hand written digit dataset. For this we trained all methods on the training set of the MNIST hand written digits dataset and tested them on a MNIST test set with different levels of occlusions. We observe that methods which employ competitive mechanisms have higher robustness against loss of information. Also the kind of the competition mechanisms plays an important role in robustness. Global feedback inhibition as employed in predictive coding/biased competition has an advantage compared to local lateral inhibition learned by an anti-Hebb rule.

  14. Modeling stochasticity and robustness in gene regulatory networks.

    Science.gov (United States)

    Garg, Abhishek; Mohanram, Kartik; Di Cara, Alessandro; De Micheli, Giovanni; Xenarios, Ioannis

    2009-06-15

    Understanding gene regulation in biological processes and modeling the robustness of underlying regulatory networks is an important problem that is currently being addressed by computational systems biologists. Lately, there has been a renewed interest in Boolean modeling techniques for gene regulatory networks (GRNs). However, due to their deterministic nature, it is often difficult to identify whether these modeling approaches are robust to the addition of stochastic noise that is widespread in gene regulatory processes. Stochasticity in Boolean models of GRNs has been addressed relatively sparingly in the past, mainly by flipping the expression of genes between different expression levels with a predefined probability. This stochasticity in nodes (SIN) model leads to over representation of noise in GRNs and hence non-correspondence with biological observations. In this article, we introduce the stochasticity in functions (SIF) model for simulating stochasticity in Boolean models of GRNs. By providing biological motivation behind the use of the SIF model and applying it to the T-helper and T-cell activation networks, we show that the SIF model provides more biologically robust results than the existing SIN model of stochasticity in GRNs. Algorithms are made available under our Boolean modeling toolbox, GenYsis. The software binaries can be downloaded from http://si2.epfl.ch/ approximately garg/genysis.html.

  15. Return Predictability, Model Uncertainty, and Robust Investment

    DEFF Research Database (Denmark)

    Lukas, Manuel

    Stock return predictability is subject to great uncertainty. In this paper we use the model confidence set approach to quantify uncertainty about expected utility from investment, accounting for potential return predictability. For monthly US data and six representative return prediction models, we...... find that confidence sets are very wide, change significantly with the predictor variables, and frequently include expected utilities for which the investor prefers not to invest. The latter motivates a robust investment strategy maximizing the minimal element of the confidence set. The robust investor...... allocates a much lower share of wealth to stocks compared to a standard investor....

  16. Three Contributions to Robust Regression Diagnostics

    Czech Academy of Sciences Publication Activity Database

    Kalina, Jan

    2015-01-01

    Roč. 11, č. 2 (2015), s. 69-78 ISSN 1336-9180 Grant - others:GA ČR(CZ) GA13-01930S; Nadační fond na podporu vědy(CZ) Neuron Institutional support: RVO:67985807 Keywords : robust regression * robust econometrics * hypothesis test ing Subject RIV: BA - General Mathematics http://www.degruyter.com/view/j/jamsi.2015.11.issue-2/jamsi-2015-0013/jamsi-2015-0013.xml?format=INT

  17. Robust Inference with Multi-way Clustering

    OpenAIRE

    A. Colin Cameron; Jonah B. Gelbach; Douglas L. Miller; Doug Miller

    2009-01-01

    In this paper we propose a variance estimator for the OLS estimator as well as for nonlinear estimators such as logit, probit and GMM. This variance estimator enables cluster-robust inference when there is two-way or multi-way clustering that is non-nested. The variance estimator extends the standard cluster-robust variance estimator or sandwich estimator for one-way clustering (e.g. Liang and Zeger (1986), Arellano (1987)) and relies on similar relatively weak distributional assumptions. Our...

  18. Robust control synthesis for uncertain dynamical systems

    Science.gov (United States)

    Byun, Kuk-Whan; Wie, Bong; Sunkel, John

    1989-01-01

    This paper presents robust control synthesis techniques for uncertain dynamical systems subject to structured parameter perturbation. Both QFT (quantitative feedback theory) and H-infinity control synthesis techniques are investigated. Although most H-infinity-related control techniques are not concerned with the structured parameter perturbation, a new way of incorporating the parameter uncertainty in the robust H-infinity control design is presented. A generic model of uncertain dynamical systems is used to illustrate the design methodologies investigated in this paper. It is shown that, for a certain noncolocated structural control problem, use of both techniques results in nonminimum phase compensation.

  19. Robustness of multiparty nonlocality to local decoherence

    International Nuclear Information System (INIS)

    Jang, Sung Soon; Cheong, Yong Wook; Kim, Jaewan; Lee, Hai-Woong

    2006-01-01

    We investigate the robustness of multiparty nonlocality under local decoherence, acting independently and equally on each subsystem. To be specific, we consider an N-qubit Greenberger-Horne-Zeilinger (GHZ) state under a depolarization, dephasing, or dissipation channel, and examine nonlocality by testing violation of the Mermin-Klyshko inequality, which is one of Bell's inequalities for multiqubit systems. The results show that the robustness of nonlocality increases with the number of qubits, and that the nonlocality of an N-qubit GHZ state with even N is extremely persistent against dephasing

  20. Robust speaker recognition in noisy environments

    CERN Document Server

    Rao, K Sreenivasa

    2014-01-01

    This book discusses speaker recognition methods to deal with realistic variable noisy environments. The text covers authentication systems for; robust noisy background environments, functions in real time and incorporated in mobile devices. The book focuses on different approaches to enhance the accuracy of speaker recognition in presence of varying background environments. The authors examine: (a) Feature compensation using multiple background models, (b) Feature mapping using data-driven stochastic models, (c) Design of super vector- based GMM-SVM framework for robust speaker recognition, (d) Total variability modeling (i-vectors) in a discriminative framework and (e) Boosting method to fuse evidences from multiple SVM models.

  1. Robust Parametric Control of Spacecraft Rendezvous

    Directory of Open Access Journals (Sweden)

    Dake Gu

    2014-01-01

    Full Text Available This paper proposes a method to design the robust parametric control for autonomous rendezvous of spacecrafts with the inertial information with uncertainty. We consider model uncertainty of traditional C-W equation to formulate the dynamic model of the relative motion. Based on eigenstructure assignment and model reference theory, a concise control law for spacecraft rendezvous is proposed which could be fixed through solving an optimization problem. The cost function considers the stabilization of the system and other performances. Simulation results illustrate the robustness and effectiveness of the proposed control.

  2. Robust cluster analysis and variable selection

    CERN Document Server

    Ritter, Gunter

    2014-01-01

    Clustering remains a vibrant area of research in statistics. Although there are many books on this topic, there are relatively few that are well founded in the theoretical aspects. In Robust Cluster Analysis and Variable Selection, Gunter Ritter presents an overview of the theory and applications of probabilistic clustering and variable selection, synthesizing the key research results of the last 50 years. The author focuses on the robust clustering methods he found to be the most useful on simulated data and real-time applications. The book provides clear guidance for the varying needs of bot

  3. Robust median estimator in logisitc regression

    Czech Academy of Sciences Publication Activity Database

    Hobza, T.; Pardo, L.; Vajda, Igor

    2008-01-01

    Roč. 138, č. 12 (2008), s. 3822-3840 ISSN 0378-3758 R&D Projects: GA MŠk 1M0572 Grant - others:Instituto Nacional de Estadistica (ES) MPO FI - IM3/136; GA MŠk(CZ) MTM 2006-06872 Institutional research plan: CEZ:AV0Z10750506 Keywords : Logistic regression * Median * Robustness * Consistency and asymptotic normality * Morgenthaler * Bianco and Yohai * Croux and Hasellbroeck Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.679, year: 2008 http://library.utia.cas.cz/separaty/2008/SI/vajda-robust%20median%20estimator%20in%20logistic%20regression.pdf

  4. Introduction to Robust Estimation and Hypothesis Testing

    CERN Document Server

    Wilcox, Rand R

    2012-01-01

    This revised book provides a thorough explanation of the foundation of robust methods, incorporating the latest updates on R and S-Plus, robust ANOVA (Analysis of Variance) and regression. It guides advanced students and other professionals through the basic strategies used for developing practical solutions to problems, and provides a brief background on the foundations of modern methods, placing the new methods in historical context. Author Rand Wilcox includes chapter exercises and many real-world examples that illustrate how various methods perform in different situations.Introduction to R

  5. Robust-mode analysis of hydrodynamic flows

    Science.gov (United States)

    Roy, Sukesh; Gord, James R.; Hua, Jia-Chen; Gunaratne, Gemunu H.

    2017-04-01

    The emergence of techniques to extract high-frequency high-resolution data introduces a new avenue for modal decomposition to assess the underlying dynamics, especially of complex flows. However, this task requires the differentiation of robust, repeatable flow constituents from noise and other irregular features of a flow. Traditional approaches involving low-pass filtering and principle components analysis have shortcomings. The approach outlined here, referred to as robust-mode analysis, is based on Koopman decomposition. Three applications to (a) a counter-rotating cellular flame state, (b) variations in financial markets, and (c) turbulent injector flows are provided.

  6. Robust adaptive control for Unmanned Aerial Vehicles

    Science.gov (United States)

    Kahveci, Nazli E.

    The objective of meeting higher endurance requirements remains a challenging task for any type and size of Unmanned Aerial Vehicles (UAVs). According to recent research studies significant energy savings can be realized through utilization of thermal currents. The navigation strategies followed across thermal regions, however, are based on rather intuitive assessments of remote pilots and lack any systematic path planning approaches. Various methods to enhance the autonomy of UAVs in soaring applications are investigated while seeking guarantees for flight performance improvements. The dynamics of the aircraft, small UAVs in particular, are affected by the environmental conditions, whereas unmodeled dynamics possibly become significant during aggressive flight maneuvers. Besides, the demanded control inputs might have a magnitude range beyond the limits dictated by the control surface actuators. The consequences of ignoring these issues can be catastrophic. Supporting this claim NASA Dryden Flight Research Center reports considerable performance degradation and even loss of stability in autonomous soaring flight tests with the subsequent risk of an aircraft crash. The existing control schemes are concluded to suffer from limited performance. Considering the aircraft dynamics and the thermal characteristics we define a vehicle-specific trajectory optimization problem to achieve increased cross-country speed and extended range of flight. In an environment with geographically dispersed set of thermals of possibly limited lifespan, we identify the similarities to the Vehicle Routing Problem (VRP) and provide both exact and approximate guidance algorithms for the navigation of automated UAVs. An additional stochastic approach is used to quantify the performance losses due to incorrect thermal data while dealing with random gust disturbances and onboard sensor measurement inaccuracies. One of the main contributions of this research is a novel adaptive control design with

  7. Robust giant magnetoresistive effect type multilayer sensor

    NARCIS (Netherlands)

    Lenssen, K.M.H.; Kuiper, A.E.T.; Roozeboom, F.

    2002-01-01

    A robust Giant Magneto Resistive effect type multilayer sensor comprising a free and a pinned ferromagnetic layer, which can withstand high temperatures and strong magnetic fields as required in automotive applications. The GMR multi-layer has an asymmetric magneto-resistive curve and enables

  8. Robust inference in sample selection models

    KAUST Repository

    Zhelonkin, Mikhail; Genton, Marc G.; Ronchetti, Elvezio

    2015-01-01

    The problem of non-random sample selectivity often occurs in practice in many fields. The classical estimators introduced by Heckman are the backbone of the standard statistical analysis of these models. However, these estimators are very sensitive to small deviations from the distributional assumptions which are often not satisfied in practice. We develop a general framework to study the robustness properties of estimators and tests in sample selection models. We derive the influence function and the change-of-variance function of Heckman's two-stage estimator, and we demonstrate the non-robustness of this estimator and its estimated variance to small deviations from the model assumed. We propose a procedure for robustifying the estimator, prove its asymptotic normality and give its asymptotic variance. Both cases with and without an exclusion restriction are covered. This allows us to construct a simple robust alternative to the sample selection bias test. We illustrate the use of our new methodology in an analysis of ambulatory expenditures and we compare the performance of the classical and robust methods in a Monte Carlo simulation study.

  9. Robust inference in sample selection models

    KAUST Repository

    Zhelonkin, Mikhail

    2015-11-20

    The problem of non-random sample selectivity often occurs in practice in many fields. The classical estimators introduced by Heckman are the backbone of the standard statistical analysis of these models. However, these estimators are very sensitive to small deviations from the distributional assumptions which are often not satisfied in practice. We develop a general framework to study the robustness properties of estimators and tests in sample selection models. We derive the influence function and the change-of-variance function of Heckman\\'s two-stage estimator, and we demonstrate the non-robustness of this estimator and its estimated variance to small deviations from the model assumed. We propose a procedure for robustifying the estimator, prove its asymptotic normality and give its asymptotic variance. Both cases with and without an exclusion restriction are covered. This allows us to construct a simple robust alternative to the sample selection bias test. We illustrate the use of our new methodology in an analysis of ambulatory expenditures and we compare the performance of the classical and robust methods in a Monte Carlo simulation study.

  10. Highly Robust Methods in Data Mining

    Czech Academy of Sciences Publication Activity Database

    Kalina, Jan

    2013-01-01

    Roč. 8, č. 1 (2013), s. 9-24 ISSN 1452-4864 Institutional support: RVO:67985807 Keywords : data mining * robust statistics * high-dimensional data * cluster analysis * logistic regression * neural networks Subject RIV: BB - Applied Statistics, Operational Research

  11. Robust Utility Maximization Under Convex Portfolio Constraints

    International Nuclear Information System (INIS)

    Matoussi, Anis; Mezghani, Hanen; Mnif, Mohamed

    2015-01-01

    We study a robust maximization problem from terminal wealth and consumption under a convex constraints on the portfolio. We state the existence and the uniqueness of the consumption–investment strategy by studying the associated quadratic backward stochastic differential equation. We characterize the optimal control by using the duality method and deriving a dynamic maximum principle

  12. Robust diamond meshes with unique wettability properties.

    Science.gov (United States)

    Yang, Yizhou; Li, Hongdong; Cheng, Shaoheng; Zou, Guangtian; Wang, Chuanxi; Lin, Quan

    2014-03-18

    Robust diamond meshes with excellent superhydrophobic and superoleophilic properties have been fabricated. Superhydrophobicity is observed for water with varying pH from 1 to 14 with good recyclability. Reversible superhydrophobicity and hydrophilicity can be easily controlled. The diamond meshes show highly efficient water-oil separation and water pH droplet transference.

  13. Robustness of dynamic systems with parameter uncertainties

    CERN Document Server

    Balemi, S; Truöl, W

    1992-01-01

    Robust Control is one of the fastest growing and promising areas of research today. In many practical systems there exist uncertainties which have to be considered in the analysis and design of control systems. In the last decade methods were developed for dealing with dynamic systems with unstructured uncertainties such as HOO_ and £I-optimal control. For systems with parameter uncertainties, the seminal paper of V. L. Kharitonov has triggered a large amount of very promising research. An international workshop dealing with all aspects of robust control was successfully organized by S. P. Bhattacharyya and L. H. Keel in San Antonio, Texas, USA in March 1991. We organized the second international workshop in this area in Ascona, Switzer­ land in April 1992. However, this second workshop was restricted to robust control of dynamic systems with parameter uncertainties with the objective to concentrate on some aspects of robust control. This book contains a collection of papers presented at the International W...

  14. Robust predictions of the interacting boson model

    International Nuclear Information System (INIS)

    Casten, R.F.; Koeln Univ.

    1994-01-01

    While most recognized for its symmetries and algebraic structure, the IBA model has other less-well-known but equally intrinsic properties which give unavoidable, parameter-free predictions. These predictions concern central aspects of low-energy nuclear collective structure. This paper outlines these ''robust'' predictions and compares them with the data

  15. Robust keyword retrieval method for OCRed text

    Science.gov (United States)

    Fujii, Yusaku; Takebe, Hiroaki; Tanaka, Hiroshi; Hotta, Yoshinobu

    2011-01-01

    Document management systems have become important because of the growing popularity of electronic filing of documents and scanning of books, magazines, manuals, etc., through a scanner or a digital camera, for storage or reading on a PC or an electronic book. Text information acquired by optical character recognition (OCR) is usually added to the electronic documents for document retrieval. Since texts generated by OCR generally include character recognition errors, robust retrieval methods have been introduced to overcome this problem. In this paper, we propose a retrieval method that is robust against both character segmentation and recognition errors. In the proposed method, the insertion of noise characters and dropping of characters in the keyword retrieval enables robustness against character segmentation errors, and character substitution in the keyword of the recognition candidate for each character in OCR or any other character enables robustness against character recognition errors. The recall rate of the proposed method was 15% higher than that of the conventional method. However, the precision rate was 64% lower.

  16. Robust Algebraic Multilevel Methods and Algorithms

    CERN Document Server

    Kraus, Johannes

    2009-01-01

    This book deals with algorithms for the solution of linear systems of algebraic equations with large-scale sparse matrices, with a focus on problems that are obtained after discretization of partial differential equations using finite element methods. Provides a systematic presentation of the recent advances in robust algebraic multilevel methods. Can be used for advanced courses on the topic.

  17. Replication and Robustness in Developmental Research

    Science.gov (United States)

    Duncan, Greg J.; Engel, Mimi; Claessens, Amy; Dowsett, Chantelle J.

    2014-01-01

    Replications and robustness checks are key elements of the scientific method and a staple in many disciplines. However, leading journals in developmental psychology rarely include explicit replications of prior research conducted by different investigators, and few require authors to establish in their articles or online appendices that their key…

  18. A Robust Alternative to the Normal Distribution.

    Science.gov (United States)

    1982-07-07

    for any Purpose of the United States Governuent DEPARTMENT OF STATISTICS t -, STANFORD UIVERSITY I STANFORD, CALIFORNIA A Robust Alternative to the...Stanford University Technical Report No. 3. [5] Bhattacharya, S. K. (1966). A Modified Bessel Function lodel in Life Testing. Metrika 10, 133-144

  19. Robust bayesian inference of generalized Pareto distribution ...

    African Journals Online (AJOL)

    En utilisant une etude exhaustive de Monte Carlo, nous prouvons que, moyennant une fonction perte generalisee adequate, on peut construire un estimateur Bayesien robuste du modele. Key words: Bayesian estimation; Extreme value; Generalized Fisher information; Gener- alized Pareto distribution; Monte Carlo; ...

  20. Robust balance shift control with posture optimization

    NARCIS (Netherlands)

    Kavafoglu, Z.; Kavafoglu, Ersan; Egges, J.

    2015-01-01

    In this paper we present a control framework which creates robust and natural balance shifting behaviours during standing. Given high-level features such as the position of the center of mass projection and the foot configurations, a kinematic posture satisfying these features is synthesized using

  1. Finite Algorithms for Robust Linear Regression

    DEFF Research Database (Denmark)

    Madsen, Kaj; Nielsen, Hans Bruun

    1990-01-01

    The Huber M-estimator for robust linear regression is analyzed. Newton type methods for solution of the problem are defined and analyzed, and finite convergence is proved. Numerical experiments with a large number of test problems demonstrate efficiency and indicate that this kind of approach may...

  2. Robust network design for multispecies conservation

    Science.gov (United States)

    Ronan Le Bras; Bistra Dilkina; Yexiang Xue; Carla P. Gomes; Kevin S. McKelvey; Michael K. Schwartz; Claire A. Montgomery

    2013-01-01

    Our work is motivated by an important network design application in computational sustainability concerning wildlife conservation. In the face of human development and climate change, it is important that conservation plans for protecting landscape connectivity exhibit certain level of robustness. While previous work has focused on conservation strategies that result...

  3. Neuromorphic Configurable Architecture for Robust Motion Estimation

    Directory of Open Access Journals (Sweden)

    Guillermo Botella

    2008-01-01

    Full Text Available The robustness of the human visual system recovering motion estimation in almost any visual situation is enviable, performing enormous calculation tasks continuously, robustly, efficiently, and effortlessly. There is obviously a great deal we can learn from our own visual system. Currently, there are several optical flow algorithms, although none of them deals efficiently with noise, illumination changes, second-order motion, occlusions, and so on. The main contribution of this work is the efficient implementation of a biologically inspired motion algorithm that borrows nature templates as inspiration in the design of architectures and makes use of a specific model of human visual motion perception: Multichannel Gradient Model (McGM. This novel customizable architecture of a neuromorphic robust optical flow can be constructed with FPGA or ASIC device using properties of the cortical motion pathway, constituting a useful framework for building future complex bioinspired systems running in real time with high computational complexity. This work includes the resource usage and performance data, and the comparison with actual systems. This hardware has many application fields like object recognition, navigation, or tracking in difficult environments due to its bioinspired and robustness properties.

  4. Robust control charts in statistical process control

    NARCIS (Netherlands)

    Nazir, H.Z.

    2014-01-01

    The presence of outliers and contaminations in the output of the process highly affects the performance of the design structures of commonly used control charts and hence makes them of less practical use. One of the solutions to deal with this problem is to use control charts which are robust

  5. Some Diagnostic Tools in Robust Econometrics

    Czech Academy of Sciences Publication Activity Database

    Kalina, Jan

    2011-01-01

    Roč. 50, č. 2 (2011), s. 55-67 ISSN 0231-9721 Grant - others:GA ČR(CZ) GA402/09/0557 Institutional research plan: CEZ:AV0Z10300504 Keywords : robust regression * autocorrelated errors * heteroscedastic regression * instrumental variables * least weighted squares Subject RIV: BB - Applied Statistics, Operational Research http://dml.cz/handle/10338.dmlcz/141754

  6. Robust estimation for ordinary differential equation models.

    Science.gov (United States)

    Cao, J; Wang, L; Xu, J

    2011-12-01

    Applied scientists often like to use ordinary differential equations (ODEs) to model complex dynamic processes that arise in biology, engineering, medicine, and many other areas. It is interesting but challenging to estimate ODE parameters from noisy data, especially when the data have some outliers. We propose a robust method to address this problem. The dynamic process is represented with a nonparametric function, which is a linear combination of basis functions. The nonparametric function is estimated by a robust penalized smoothing method. The penalty term is defined with the parametric ODE model, which controls the roughness of the nonparametric function and maintains the fidelity of the nonparametric function to the ODE model. The basis coefficients and ODE parameters are estimated in two nested levels of optimization. The coefficient estimates are treated as an implicit function of ODE parameters, which enables one to derive the analytic gradients for optimization using the implicit function theorem. Simulation studies show that the robust method gives satisfactory estimates for the ODE parameters from noisy data with outliers. The robust method is demonstrated by estimating a predator-prey ODE model from real ecological data. © 2011, The International Biometric Society.

  7. Chromatin regulators, phenotypic robustness and autism risk

    Directory of Open Access Journals (Sweden)

    Reut eSuliman

    2014-04-01

    Full Text Available Though extensively characterized clinically, the causes of autism spectrum disorder (ASD remain a mystery. ASD is known to have a strong genetic basis, but it is genetically very heterogeneous. Recent studies have estimated that de novo disruptive mutations in hundreds of genes may contribute to ASD. However, it is unclear how it is possible for mutations in so many different genes to contribute to ASD. Recent findings suggest that many of the mutations disrupt genes involved in transcription regulation that are expressed prenatally in the developing brain. De novo disruptive mutations are also more frequent in girls with ASD, despite the fact that ASD is more prevalent in boys. In this paper, we hypothesize that loss of robustness may contribute to ASD. Loss of phenotypic robustness may be caused by mutations that disrupt capacitors that operate in the developing brain. This may lead to the release of cryptic genetic variation that contributes to ASD. Reduced robustness is consistent with the observed variability in expressivity and incomplete penetrance. It is also consistent with the hypothesis that the development of the female brain is more robust, and it may explain the higher rate and severity of disruptive de novo mutations in girls with ASD.

  8. Robust and Adaptive Control With Aerospace Applications

    CERN Document Server

    Lavretsky, Eugene

    2013-01-01

    Robust and Adaptive Control shows the reader how to produce consistent and accurate controllers that operate in the presence of uncertainties and unforeseen events. Driven by aerospace applications the focus of the book is primarily on continuous-dynamical systems.  The text is a three-part treatment, beginning with robust and optimal linear control methods and moving on to a self-contained presentation of the design and analysis of model reference adaptive control (MRAC) for nonlinear uncertain dynamical systems. Recent extensions and modifications to MRAC design are included, as are guidelines for combining robust optimal and MRAC controllers. Features of the text include: ·         case studies that demonstrate the benefits of robust and adaptive control for piloted, autonomous and experimental aerial platforms; ·         detailed background material for each chapter to motivate theoretical developments; ·         realistic examples and simulation data illustrating key features ...

  9. Robust Pedestrian Navigation for Challenging Applications

    OpenAIRE

    Gilliéron, PY; Renaudin, V

    2009-01-01

    Presentation of a concept for robust indoor navigation. The concept is based on three key elements: - the use of an absolute geographical reference - the hybridisation of complementary technologies - specific motion models. This concept is illustrated by the means of two applications: the urban displacement of blind people and the indoor guidance of fire-fighters

  10. Robust online face tracking-by-detection

    NARCIS (Netherlands)

    Comaschi, F.; Stuijk, S.; Basten, T.; Corporaal, H.

    2016-01-01

    The problem of online face tracking from unconstrained videos is still unresolved. Challenges range from coping with severe online appearance variations to coping with occlusion. We propose RFTD (Robust Face Tracking-by-Detection), a system which combines tracking and detection into a single

  11. Robust control investigations for equipment loaded panels

    DEFF Research Database (Denmark)

    Aglietti, G.S.; Langley, R.S.; Rogers, E.

    1998-01-01

    This paper develops a modelling technique for equipment load panels which directly produces (adequate) models of the underlying dynamics on which to base robust controller design/evaluations. This technique is based on the use of the Lagrange's equations of motion and the resulting models...

  12. Robust glint detection through homography normalization

    DEFF Research Database (Denmark)

    Hansen, Dan Witzner; Roholm, Lars; García Ferreiros, Iván

    2014-01-01

    A novel normalization principle for robust glint detection is presented. The method is based on geometric properties of corneal reflections and allows for simple and effective detection of glints even in the presence of several spurious and identically appearing reflections. The method is tested...

  13. Robust power spectral estimation for EEG data.

    Science.gov (United States)

    Melman, Tamar; Victor, Jonathan D

    2016-08-01

    Typical electroencephalogram (EEG) recordings often contain substantial artifact. These artifacts, often large and intermittent, can interfere with quantification of the EEG via its power spectrum. To reduce the impact of artifact, EEG records are typically cleaned by a preprocessing stage that removes individual segments or components of the recording. However, such preprocessing can introduce bias, discard available signal, and be labor-intensive. With this motivation, we present a method that uses robust statistics to reduce dependence on preprocessing by minimizing the effect of large intermittent outliers on the spectral estimates. Using the multitaper method (Thomson, 1982) as a starting point, we replaced the final step of the standard power spectrum calculation with a quantile-based estimator, and the Jackknife approach to confidence intervals with a Bayesian approach. The method is implemented in provided MATLAB modules, which extend the widely used Chronux toolbox. Using both simulated and human data, we show that in the presence of large intermittent outliers, the robust method produces improved estimates of the power spectrum, and that the Bayesian confidence intervals yield close-to-veridical coverage factors. The robust method, as compared to the standard method, is less affected by artifact: inclusion of outliers produces fewer changes in the shape of the power spectrum as well as in the coverage factor. In the presence of large intermittent outliers, the robust method can reduce dependence on data preprocessing as compared to standard methods of spectral estimation. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Chance constrained uncertain classification via robust optimization

    NARCIS (Netherlands)

    Ben-Tal, A.; Bhadra, S.; Bhattacharayya, C.; Saketha Nat, J.

    2011-01-01

    This paper studies the problem of constructing robust classifiers when the training is plagued with uncertainty. The problem is posed as a Chance-Constrained Program (CCP) which ensures that the uncertain data points are classified correctly with high probability. Unfortunately such a CCP turns out

  15. Robust Geometric Control of a Distillation Column

    DEFF Research Database (Denmark)

    Kymmel, Mogens; Andersen, Henrik Weisberg

    1987-01-01

    A frequency domain method, which makes it possible to adjust multivariable controllers with respect to both nominal performance and robustness, is presented. The basic idea in the approach is that the designer assigns objectives such as steady-state tracking, maximum resonance peaks, bandwidth, m...... is used to examine and improve geometric control of a binary distillation column....

  16. Quantifying the robustness of metro networks

    NARCIS (Netherlands)

    Wang, X.; Koç, Y.; Derrible, S.; Nasir Ahmad, Sk.; Kooij, R.E.

    2015-01-01

    Metros (heavy rail transit systems) are integral parts of urban transportation systems. Failures in their operations can have serious impacts on urban mobility, and measuring their robustness is therefore critical. Moreover, as physical networks, metros can be viewed as network topological entities,

  17. Robust Refinement as Implemented in TOPAS

    Energy Technology Data Exchange (ETDEWEB)

    Stone, K.; Stephens, P

    2010-01-01

    A robust refinement procedure is implemented in the program TOPAS through an iterative reweighting of the data. Examples are given of the procedure as applied to fitting partially overlapped peaks by full and partial models and also of the structures of ibuprofen and acetaminophen in the presence of unmodeled impurity contributions

  18. Robust Satisfiability of Systems of Equations

    Czech Academy of Sciences Publication Activity Database

    Franek, Peter; Krčál, M.

    2015-01-01

    Roč. 62, č. 4 (2015), Article 26 ISSN 0004-5411 R&D Projects: GA ČR GBP202/12/G061 Grant - others:GA MŠk(CZ) LL1201 Institutional support: RVO:67985807 Keywords : nonlinear equations * satisfability * undecibility * topological extensions * uncertainty * robustness Subject RIV: IN - Informatics, Computer Science Impact factor: 1.803, year: 2015

  19. Robust fitting of diurnal brightness temperature cycle

    CSIR Research Space (South Africa)

    Udahemuka, G

    2007-11-01

    Full Text Available for a pixel concerned. Robust fitting of observed Diurnal Temperature Cycle (DTC) taken over a day of a given pixel without cloud cover and other abnormally conditions such as fire can give a data based brightness temperature model for a given pixel...

  20. Interrogating the topological robustness of gene regulatory circuits by randomization.

    Directory of Open Access Journals (Sweden)

    Bin Huang

    2017-03-01

    Full Text Available One of the most important roles of cells is performing their cellular tasks properly for survival. Cells usually achieve robust functionality, for example, cell-fate decision-making and signal transduction, through multiple layers of regulation involving many genes. Despite the combinatorial complexity of gene regulation, its quantitative behavior has been typically studied on the basis of experimentally verified core gene regulatory circuitry, composed of a small set of important elements. It is still unclear how such a core circuit operates in the presence of many other regulatory molecules and in a crowded and noisy cellular environment. Here we report a new computational method, named random circuit perturbation (RACIPE, for interrogating the robust dynamical behavior of a gene regulatory circuit even without accurate measurements of circuit kinetic parameters. RACIPE generates an ensemble of random kinetic models corresponding to a fixed circuit topology, and utilizes statistical tools to identify generic properties of the circuit. By applying RACIPE to simple toggle-switch-like motifs, we observed that the stable states of all models converge to experimentally observed gene state clusters even when the parameters are strongly perturbed. RACIPE was further applied to a proposed 22-gene network of the Epithelial-to-Mesenchymal Transition (EMT, from which we identified four experimentally observed gene states, including the states that are associated with two different types of hybrid Epithelial/Mesenchymal phenotypes. Our results suggest that dynamics of a gene circuit is mainly determined by its topology, not by detailed circuit parameters. Our work provides a theoretical foundation for circuit-based systems biology modeling. We anticipate RACIPE to be a powerful tool to predict and decode circuit design principles in an unbiased manner, and to quantitatively evaluate the robustness and heterogeneity of gene expression.

  1. A new robust adaptive controller for vibration control of active engine mount subjected to large uncertainties

    International Nuclear Information System (INIS)

    Fakhari, Vahid; Choi, Seung-Bok; Cho, Chang-Hyun

    2015-01-01

    This work presents a new robust model reference adaptive control (MRAC) for vibration control caused from vehicle engine using an electromagnetic type of active engine mount. Vibration isolation performances of the active mount associated with the robust controller are evaluated in the presence of large uncertainties. As a first step, an active mount with linear solenoid actuator is prepared and its dynamic model is identified via experimental test. Subsequently, a new robust MRAC based on the gradient method with σ-modification is designed by selecting a proper reference model. In designing the robust adaptive control, structured (parametric) uncertainties in the stiffness of the passive part of the mount and in damping ratio of the active part of the mount are considered to investigate the robustness of the proposed controller. Experimental and simulation results are presented to evaluate performance focusing on the robustness behavior of the controller in the face of large uncertainties. The obtained results show that the proposed controller can sufficiently provide the robust vibration control performance even in the presence of large uncertainties showing an effective vibration isolation. (paper)

  2. Robustness of Linear Systems towards Multi-Dissipative Pertubations

    DEFF Research Database (Denmark)

    Thygesen, Uffe Høgsbro; Poulsen, Niels Kjølstad

    1997-01-01

    We consider the question of robust stability of a linear time invariant plant subject to dynamic perturbations, which are dissipative in the sense of Willems with respect to several quadratic supply rates. For instance, parasitic dynamics are often both small gain and passive. We reduce several...... robustness analysis questions to linear matrix inequalities: robust stability, robust H2 performance and robust performance in presence of disturbances with finite signal-to-noise ratios...

  3. Robust multi-tissue gene panel for cancer detection

    Directory of Open Access Journals (Sweden)

    Talantov Dmitri

    2010-06-01

    Full Text Available Abstract Background We have identified a set of genes whose relative mRNA expression levels in various solid tumors can be used to robustly distinguish cancer from matching normal tissue. Our current feature set consists of 113 gene probes for 104 unique genes, originally identified as differentially expressed in solid primary tumors in microarray data on Affymetrix HG-U133A platform in five tissue types: breast, colon, lung, prostate and ovary. For each dataset, we first identified a set of genes significantly differentially expressed in tumor vs. normal tissue at p-value = 0.05 using an experimentally derived error model. Our common cancer gene panel is the intersection of these sets of significantly dysregulated genes and can distinguish tumors from normal tissue on all these five tissue types. Methods Frozen tumor specimens were obtained from two commercial vendors Clinomics (Pittsfield, MA and Asterand (Detroit, MI. Biotinylated targets were prepared using published methods (Affymetrix, CA and hybridized to Affymetrix U133A GeneChips (Affymetrix, CA. Expression values for each gene were calculated using Affymetrix GeneChip analysis software MAS 5.0. We then used a software package called Genes@Work for differential expression discovery, and SVM light linear kernel for building classification models. Results We validate the predictability of this gene list on several publicly available data sets generated on the same platform. Of note, when analysing the lung cancer data set of Spira et al, using an SVM linear kernel classifier, our gene panel had 94.7% leave-one-out accuracy compared to 87.8% using the gene panel in the original paper. In addition, we performed high-throughput validation on the Dana Farber Cancer Institute GCOD database and several GEO datasets. Conclusions Our result showed the potential for this panel as a robust classification tool for multiple tumor types on the Affymetrix platform, as well as other whole genome arrays

  4. Confidence from uncertainty - A multi-target drug screening method from robust control theory

    Directory of Open Access Journals (Sweden)

    Petzold Linda R

    2010-11-01

    Full Text Available Abstract Background Robustness is a recognized feature of biological systems that evolved as a defence to environmental variability. Complex diseases such as diabetes, cancer, bacterial and viral infections, exploit the same mechanisms that allow for robust behaviour in healthy conditions to ensure their own continuance. Single drug therapies, while generally potent regulators of their specific protein/gene targets, often fail to counter the robustness of the disease in question. Multi-drug therapies offer a powerful means to restore disrupted biological networks, by targeting the subsystem of interest while preventing the diseased network from reconciling through available, redundant mechanisms. Modelling techniques are needed to manage the high number of combinatorial possibilities arising in multi-drug therapeutic design, and identify synergistic targets that are robust to system uncertainty. Results We present the application of a method from robust control theory, Structured Singular Value or μ- analysis, to identify highly effective multi-drug therapies by using robustness in the face of uncertainty as a new means of target discrimination. We illustrate the method by means of a case study of a negative feedback network motif subject to parametric uncertainty. Conclusions The paper contributes to the development of effective methods for drug screening in the context of network modelling affected by parametric uncertainty. The results have wide applicability for the analysis of different sources of uncertainty like noise experienced in the data, neglected dynamics, or intrinsic biological variability.

  5. Robust Parameter Coordination for Multidisciplinary Design

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper introduced a robust parameter coordination method to analyze parameter uncertainties so as to predict conflicts and coordinate parameters in multidisciplinary design. The proposed method is based on constraints network, which gives a formulated model to analyze the coupling effects between design variables and product specifications. In this model, interval boxes are adopted to describe the uncertainty of design parameters quantitatively to enhance the design robustness. To solve this constraint network model, a general consistent algorithm framework is designed and implemented with interval arithmetic and the genetic algorithm, which can deal with both algebraic and ordinary differential equations. With the help of this method, designers could infer the consistent solution space from the given specifications. A case study involving the design of a bogie dumping system demonstrates the usefulness of this approach.

  6. Robust lyapunov controller for uncertain systems

    KAUST Repository

    Laleg-Kirati, Taous-Meriem

    2017-02-23

    Various examples of systems and methods are provided for Lyapunov control for uncertain systems. In one example, a system includes a process plant and a robust Lyapunov controller configured to control an input of the process plant. The robust Lyapunov controller includes an inner closed loop Lyapunov controller and an outer closed loop error stabilizer. In another example, a method includes monitoring a system output of a process plant; generating an estimated system control input based upon a defined output reference; generating a system control input using the estimated system control input and a compensation term; and adjusting the process plant based upon the system control input to force the system output to track the defined output reference. An inner closed loop Lyapunov controller can generate the estimated system control input and an outer closed loop error stabilizer can generate the system control input.

  7. Communicating via robust synchronization of chaotic lasers

    International Nuclear Information System (INIS)

    Lopez-Gutierrez, R.M.; Posadas-Castillo, C.; Lopez-Mancilla, D.; Cruz-Hernandez, C.

    2009-01-01

    In this paper, the robust synchronization problem for coupled chaotic Nd:YAG lasers is addressed. We resort to complex systems theory to achieve chaos synchronization. Based on stability theory, it is shown that the state trajectories of the perturbed error synchronization are ultimately bounded, provided the unperturbed synchronization error system is exponentially stable, and some conditions on the bounds of the perturbation terms are satisfied. So that, encoding, transmission, and decoding in chaotic optical communications are presented. We analyze the transmission and recovery of encrypted information when parameter mismatches are considered. Computer simulations are provided to show the effectiveness of this robustness synchronization property, we present the encrypted transmission of image messages, and we show that, the transmitted image is faithfully recovered.

  8. Communicating via robust synchronization of chaotic lasers

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Gutierrez, R.M. [Engineering Faculty, Baja California Autonomous University (UABC), Km. 103 Carret. Tij-Ens., 22860 Ensenada, B.C. (Mexico); Posadas-Castillo, C. [Engineering Faculty, Baja California Autonomous University (UABC), Km. 103 Carret. Tij-Ens., 22860 Ensenada, B.C. (Mexico); FIME, Autonomous University of Nuevo Leon (UANL), Pedro de Alba, S.N., Cd. Universitaria, San Nicolas de los Garza, NL (Mexico); Lopez-Mancilla, D. [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de los Lagos, Universidad de Guadalajara (CULagos-UdeG), Enrique Diaz de Leon s/n, 47460 Lagos de Moreno, Jal. (Mexico); Cruz-Hernandez, C. [Electronics and Telecommunications Department, Scientific Research and Advanced Studies of Ensenada (CICESE), Km. 107 Carret. Tij-Ens., 22860 Ensenada, B.C. (Mexico)], E-mail: ccruz@cicese.mx

    2009-10-15

    In this paper, the robust synchronization problem for coupled chaotic Nd:YAG lasers is addressed. We resort to complex systems theory to achieve chaos synchronization. Based on stability theory, it is shown that the state trajectories of the perturbed error synchronization are ultimately bounded, provided the unperturbed synchronization error system is exponentially stable, and some conditions on the bounds of the perturbation terms are satisfied. So that, encoding, transmission, and decoding in chaotic optical communications are presented. We analyze the transmission and recovery of encrypted information when parameter mismatches are considered. Computer simulations are provided to show the effectiveness of this robustness synchronization property, we present the encrypted transmission of image messages, and we show that, the transmitted image is faithfully recovered.

  9. Robust small area prediction for counts.

    Science.gov (United States)

    Tzavidis, Nikos; Ranalli, M Giovanna; Salvati, Nicola; Dreassi, Emanuela; Chambers, Ray

    2015-06-01

    A new semiparametric approach to model-based small area prediction for counts is proposed and used for estimating the average number of visits to physicians for Health Districts in Central Italy. The proposed small area predictor can be viewed as an outlier robust alternative to the more commonly used empirical plug-in predictor that is based on a Poisson generalized linear mixed model with Gaussian random effects. Results from the real data application and from a simulation experiment confirm that the proposed small area predictor has good robustness properties and in some cases can be more efficient than alternative small area approaches. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  10. Robust quantum optimizer with full connectivity.

    Science.gov (United States)

    Nigg, Simon E; Lörch, Niels; Tiwari, Rakesh P

    2017-04-01

    Quantum phenomena have the potential to speed up the solution of hard optimization problems. For example, quantum annealing, based on the quantum tunneling effect, has recently been shown to scale exponentially better with system size than classical simulated annealing. However, current realizations of quantum annealers with superconducting qubits face two major challenges. First, the connectivity between the qubits is limited, excluding many optimization problems from a direct implementation. Second, decoherence degrades the success probability of the optimization. We address both of these shortcomings and propose an architecture in which the qubits are robustly encoded in continuous variable degrees of freedom. By leveraging the phenomenon of flux quantization, all-to-all connectivity with sufficient tunability to implement many relevant optimization problems is obtained without overhead. Furthermore, we demonstrate the robustness of this architecture by simulating the optimal solution of a small instance of the nondeterministic polynomial-time hard (NP-hard) and fully connected number partitioning problem in the presence of dissipation.

  11. Robust haptic large distance telemanipulation for ITER

    International Nuclear Information System (INIS)

    Heck, D.J.F.; Heemskerk, C.J.M.; Koning, J.F.; Abbasi, A.; Nijmeijer, H.

    2013-01-01

    Highlights: • ITER remote handling maintenance can be controlled safely over a large distance. • Bilateral teleoperation experiments were performed in a local network. • Wave variables make the controller robust against constant communication delays. • Master and slave position synchronization guaranteed by proportional action. -- Abstract: During shutdowns, maintenance crews are expected to work in 24/6 shifts to perform critical remote handling maintenance tasks on the ITER system. In this article, we investigate the possibility to safely perform these haptic maintenance tasks remotely from control stations located anywhere around the world. To guarantee stability in time delayed bilateral teleoperation, the symmetric position tracking controller using wave variables is selected. This algorithm guarantees robustness against communication delays, can eliminate wave reflections and provide position synchronization of the master and slave devices. Experiments have been conducted under realistic local network bandwidth, latency and jitter constraints. They show sufficient transparency even for substantial communication delays

  12. Design of Robust Neural Network Classifiers

    DEFF Research Database (Denmark)

    Larsen, Jan; Andersen, Lars Nonboe; Hintz-Madsen, Mads

    1998-01-01

    This paper addresses a new framework for designing robust neural network classifiers. The network is optimized using the maximum a posteriori technique, i.e., the cost function is the sum of the log-likelihood and a regularization term (prior). In order to perform robust classification, we present...... a modified likelihood function which incorporates the potential risk of outliers in the data. This leads to the introduction of a new parameter, the outlier probability. Designing the neural classifier involves optimization of network weights as well as outlier probability and regularization parameters. We...... suggest to adapt the outlier probability and regularisation parameters by minimizing the error on a validation set, and a simple gradient descent scheme is derived. In addition, the framework allows for constructing a simple outlier detector. Experiments with artificial data demonstrate the potential...

  13. Robustness and modular structure in networks

    DEFF Research Database (Denmark)

    Bagrow, James P.; Lehmann, Sune; Ahn, Yong-Yeol

    2015-01-01

    -12]. Many complex systems, from power grids and the Internet to the brain and society [13-15], can be modeled using modular networks comprised of small, densely connected groups of nodes [16, 17]. These modules often overlap, with network elements belonging to multiple modules [18, 19]. Yet existing work...... on robustness has not considered the role of overlapping, modular structure. Here we study the robustness of these systems to the failure of elements. We show analytically and empirically that it is possible for the modules themselves to become uncoupled or non-overlapping well before the network disintegrates....... If overlapping modular organization plays a role in overall functionality, networks may be far more vulnerable than predicted by conventional percolation theory....

  14. Track filtering by robust neural network

    International Nuclear Information System (INIS)

    Baginyan, S.A.; Kisel', I.V.; Konotopskaya, E.V.; Ososkov, G.A.

    1993-01-01

    In the present paper we study the following problems of track information extraction by the artificial neural network (ANN) rotor model: providing initial ANN configuration by an algorithm general enough to be applicable for any discrete detector in- or out of a magnetic field; robustness to heavy contaminated raw data (up to 100% signal-to-noise ratio); stability to the growing event multiplicity. These problems were carried out by corresponding innovations of our model, namely: by a special one-dimensional histogramming, by multiplying weights by a specially designed robust multiplier, and by replacing the simulated annealing schedule by ANN dynamics with an optimally fixed temperature. Our approach is valid for both circular and straight (non-magnetic) tracks and tested on 2D simulated data contaminated by 100% noise points distributed uniformly. To be closer to some reality in our simulation, we keep parameters of the cylindrical spectrometer ARES. 12 refs.; 9 figs

  15. Robustness analysis method for orbit control

    Science.gov (United States)

    Zhang, Jingrui; Yang, Keying; Qi, Rui; Zhao, Shuge; Li, Yanyan

    2017-08-01

    Satellite orbits require periodical maintenance due to the presence of perturbations. However, random errors caused by inaccurate orbit determination and thrust implementation may lead to failure of the orbit control strategy. Therefore, it is necessary to analyze the robustness of the orbit control methods. Feasible strategies which are tolerant to errors of a certain magnitude can be developed to perform reliable orbit control for the satellite. In this paper, first, the orbital dynamic model is formulated by Gauss' form of the planetary equation using the mean orbit elements; the atmospheric drag and the Earth's non-spherical perturbations are taken into consideration in this model. Second, an impulsive control strategy employing the differential correction algorithm is developed to maintain the satellite trajectory parameters in given ranges. Finally, the robustness of the impulsive control method is analyzed through Monte Carlo simulations while taking orbit determination error and thrust error into account.

  16. The Robustness of High Danish National Happiness

    DEFF Research Database (Denmark)

    Hussain, M. Azhar

    2014-01-01

    Denmark’s top position in various rankings of country happiness is well-documented. This study goes beyond the national average comparisons and investigates whether Denmark’s top position is also found when we disaggregate data in line with social categories often used within the social sciences....... The central measure is the empirical probability that a given population subgroup in Denmark has significantly higher happiness compared to another country’s similar subgroup in a given year. All five rounds of the European Social Survey are used but only the sixteen countries that were surveyed in each...... of the five rounds are included in this study. The results show that Denmark’s position at the top of the happiness scale is also robust when we look at population subgroups, but not in the sense that Denmark dominates all countries for all years. Instead, a modified version of robustness is necessary...

  17. Reliability and Robustness Evaluation of Timber Structures

    DEFF Research Database (Denmark)

    Cizmar, Dean; Sørensen, John Dalsgaard; Kirkegaard, Poul Henning

    In the last few decades there have been intensely research concerning reliability of timber structures. This is primarily because there is an increased focus on society on sustainability and environmental aspects. Modern timber as a building material is also being competitive compared to concrete...... and steel. However, reliability models applied to timber were always related to individual components but not the systems. as any real structure is a complex system, system behaviour must be of a particular interest. In the chapter 1 of this document an overview of stochastic models for strength and loads...... (deterministic, probabilistic and risk based approaches) of the robustness are given. Chapter 3 deals more detailed with the robustness of timber structures....

  18. Robust haptic large distance telemanipulation for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Heck, D.J.F., E-mail: d.j.f.heck@tue.nl [Eindhoven University of Technology, Department of Mechanical Engineering, Eindhoven (Netherlands); Heemskerk, C.J.M.; Koning, J.F. [Heemskerk Innovative Technologies, Sassenheim (Netherlands); Abbasi, A.; Nijmeijer, H. [Eindhoven University of Technology, Department of Mechanical Engineering, Eindhoven (Netherlands)

    2013-10-15

    Highlights: • ITER remote handling maintenance can be controlled safely over a large distance. • Bilateral teleoperation experiments were performed in a local network. • Wave variables make the controller robust against constant communication delays. • Master and slave position synchronization guaranteed by proportional action. -- Abstract: During shutdowns, maintenance crews are expected to work in 24/6 shifts to perform critical remote handling maintenance tasks on the ITER system. In this article, we investigate the possibility to safely perform these haptic maintenance tasks remotely from control stations located anywhere around the world. To guarantee stability in time delayed bilateral teleoperation, the symmetric position tracking controller using wave variables is selected. This algorithm guarantees robustness against communication delays, can eliminate wave reflections and provide position synchronization of the master and slave devices. Experiments have been conducted under realistic local network bandwidth, latency and jitter constraints. They show sufficient transparency even for substantial communication delays.

  19. Robust blood-glucose control using Mathematica.

    Science.gov (United States)

    Kovács, Levente; Paláncz, Béla; Benyó, Balázs; Török, László; Benyó, Zoltán

    2006-01-01

    A robust control design on frequency domain using Mathematica is presented for regularization of glucose level in type I diabetes persons under intensive care. The method originally proposed under Mathematica by Helton and Merino, --now with an improved disturbance rejection constraint inequality--is employed, using a three-state minimal patient model. The robustness of the resulted high-order linear controller is demonstrated by nonlinear closed loop simulation in state-space, in case of standard meal disturbances and is compared with H infinity design implemented with the mu-toolbox of Matlab. The controller designed with model parameters represented the most favorable plant dynamics from the point of view of control purposes, can operate properly even in case of parameter values of the worst-case scenario.

  20. Model predictive control classical, robust and stochastic

    CERN Document Server

    Kouvaritakis, Basil

    2016-01-01

    For the first time, a textbook that brings together classical predictive control with treatment of up-to-date robust and stochastic techniques. Model Predictive Control describes the development of tractable algorithms for uncertain, stochastic, constrained systems. The starting point is classical predictive control and the appropriate formulation of performance objectives and constraints to provide guarantees of closed-loop stability and performance. Moving on to robust predictive control, the text explains how similar guarantees may be obtained for cases in which the model describing the system dynamics is subject to additive disturbances and parametric uncertainties. Open- and closed-loop optimization are considered and the state of the art in computationally tractable methods based on uncertainty tubes presented for systems with additive model uncertainty. Finally, the tube framework is also applied to model predictive control problems involving hard or probabilistic constraints for the cases of multiplic...