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  1. Opioid Use and Neural Tube Defects

    MedlinePLUS

    ... of neural tube defects. Obstetrics and Gynecology . 2013: epub ahead of print. References Broussard CS, Rasmussen SA, ... file Text file Zip Archive file SAS file ePub file RIS file Page last reviewed: October 21, ...

  2. Folic Acid Helps Prevent Neural Tube Defects

    MedlinePLUS

    ... What's this? Submit Button Past Emails CDC Features Folic Acid Helps Prevent Neural Tube Defects Language: English Español ( ... every day before and during pregnancy. What Is Folic Acid? Folic acid is a B vitamin. Our bodies ...

  3. Neural Tube Defects, Folic Acid and Methylation

    PubMed Central

    Imbard, Apolline; Benoist, Jean-François; Blom, Henk J.

    2013-01-01

    Neural tube defects (NTDs) are common complex congenital malformations resulting from failure of the neural tube closure during embryogenesis. It is established that folic acid supplementation decreases the prevalence of NTDs, which has led to national public health policies regarding folic acid. To date, animal studies have not provided sufficient information to establish the metabolic and/or genomic mechanism(s) underlying human folic acid responsiveness in NTDs. However, several lines of evidence suggest that not only folates but also choline, B12 and methylation metabolisms are involved in NTDs. Decreased B12 vitamin and increased total choline or homocysteine in maternal blood have been shown to be associated with increased NTDs risk. Several polymorphisms of genes involved in these pathways have also been implicated in risk of development of NTDs. This raises the question whether supplementation with B12 vitamin, betaine or other methylation donors in addition to folic acid periconceptional supplementation will further reduce NTD risk. The objective of this article is to review the role of methylation metabolism in the onset of neural tube defects. PMID:24048206

  4. Nodal signaling is required for closure of the anterior neural tube in zebrafish

    PubMed Central

    Aquilina-Beck, Allisan; Ilagan, Kristine; Liu, Qin; Liang, Jennifer O

    2007-01-01

    Background Nodals are secreted signaling proteins with many roles in vertebrate development. Here, we identify a new role for Nodal signaling in regulating closure of the rostral neural tube of zebrafish. Results We find that the neural tube in the presumptive forebrain fails to close in zebrafish Nodal signaling mutants. For instance, the cells that will give rise to the pineal organ fail to move from the lateral edges of the neural plate to the midline of the diencephalon. The open neural tube in Nodal signaling mutants may be due in part to reduced function of N-cadherin, a cell adhesion molecule expressed in the neural tube and required for neural tube closure. N-cadherin expression and localization to the membrane are reduced in fish that lack Nodal signaling. Further, N-cadherin mutants and morphants have a pineal phenotype similar to that of mutants with deficiencies in the Nodal pathway. Overexpression of an activated form of the TGF? Type I receptor Taram-A (Taram-A*) cell autonomously rescues mesendoderm formation in fish with a severe decrease in Nodal signaling. We find that overexpression of Taram-A* also corrects their open neural tube defect. This suggests that, as in mammals, the mesoderm and endoderm have an important role in regulating closure of the anterior neural tube of zebrafish. Conclusion This work helps establish a role for Nodal signals in neurulation, and suggests that defects in Nodal signaling could underlie human neural tube defects such as exencephaly, a fatal condition characterized by an open neural tube in the anterior brain. PMID:17996054

  5. Genetic, Epigenetic, and Environmental Contributions to Neural Tube Closure

    PubMed Central

    Wilde, Jonathan J.; Petersen, Juliette R.; Niswander, Lee

    2015-01-01

    The formation of the embryonic brain and spinal cord begins as the neural plate bends to form the neural folds, which meet and fuse to close the neural tube. The neural ectoderm and surrounding tissues also coordinate proliferation, differentiation, and patterning. This highly orchestrated process is susceptible to disruption, leading to neural tube defects (NTDs), a common birth defect. Here, we highlight genetic and epigenetic contributions to neural tube closure. We describe an online database we created as a resource for researchers, geneticists, and clinicians. Neural tube closure is sensitive to environmental influences, and we discuss disruptive causes, preventative measures, and possible mechanisms. New technologies will move beyond candidate genes in small cohort studies toward unbiased discoveries in sporadic NTD cases. This will uncover the genetic complexity of NTDs and critical gene-gene interactions. Animal models can reveal the causative nature of genetic variants, the genetic interrelationships, and the mechanisms underlying environmental influences. PMID:25292356

  6. How Do Health Care Providers Diagnose Neural Tube Defects?

    MedlinePLUS

    ... Information Clinical Trials Resources and Publications How do health care providers diagnose neural tube defects? Skip sharing on ... AFP, as well as high levels of acetylcholinesterase; health care providers might conduct this test to confirm high ...

  7. Neural Tube Defects: From a Proteomic Standpoint

    PubMed Central

    Puvirajesinghe, Tania M.; Borg, Jean-Paul

    2015-01-01

    Neural tube defects (NTDs) are congenital birth defects classified according to their resulting morphological characteristics in newborn patients. Current diagnosis of NTDs relies largely on the structural evaluation of fetuses using ultrasound imaging, with biochemical characterization used as secondary screening tools. The multigene etiology of NTDs has been aided by genetic studies, which have discovered panels of genes mutated in these diseases that encode receptors and cytoplasmic signaling molecules with poorly defined functions. Animal models ranging from flies to mice have been used to determine the function of these genes and identify their associated molecular cascades. More emphasis is now being placed on the identification of biochemical markers from clinical samples and model systems based on mass spectrometry, which open novel avenues in the understanding of NTDs at protein, metabolic and molecular levels. This article reviews how the use of proteomics can push forward the identification of novel biomarkers and molecular networks implicated in NTDs, an indispensable step in the improvement of patient management. PMID:25789708

  8. Aneuploidy among prenatally detected neural tube defects

    SciTech Connect

    Hume, R.F. Jr.; Lampinen, J.; Martin, L.S.; Johnson, M.P.; Evans, M.I.

    1996-01-11

    We have reported previously a 10% aneuploidy detection rate among 39 cases of fetal neural tube defects (NTD). Subsequently we amassed an additional experience of over 17,000 prenatal diagnosis cases over a 5-year period. During this period 106 cases of NTDs were identified; 44 with anencephaly, 62 with open spina bifida. The average maternal age of this population with NTDs was 29 years (15-40); 6 patients declined amniocentesis. Six of 100 cytogenetic studies were aneuploid; on anencephalic fetus had inherited a maternal marker chromosome, and 5 NTD cases had trisomy 18. The average maternal age of the aneuploid cases was 21 (19-40); 3 were 35 years or older. Four of 5 trisomy 18 cases had multiple congenital anomalies (MCA). The overall aneuploidy detection rate in our cohort was 5-6, while aneuploidy occurred in 2% of the isolated NTD cases, and 24% of the MCA cases. Combining the earlier experience, 4/39 aneuploidy (2 trisomy 18, 4p+, del 13q) yields an aneuploidy detection frequency of 10/145 (7%), of which most (7/10) had trisomy 18. These data support fetal karyotyping for accurate diagnosis, prognosis, and recurrence-risk counseling. 5 refs., 2 tabs.

  9. 21 CFR 101.79 - Health claims: Folate and neural tube defects.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... folate may reduce the risk of neural tube defects. The strongest evidence for this relationship comes... at risk of recurrence of a neural tube defect pregnancy who consumed a supplement containing 4... pregnancy had a reduced risk of having a child with a neural tube defect. (Products containing this level...

  10. 21 CFR 101.79 - Health claims: Folate and neural tube defects.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... folate may reduce the risk of neural tube defects. The strongest evidence for this relationship comes... at risk of recurrence of a neural tube defect pregnancy who consumed a supplement containing 4... pregnancy had a reduced risk of having a child with a neural tube defect. (Products containing this level...

  11. Fate Specification of Neural Plate Border by Canonical Wnt Signaling and Grhl3 is Crucial for Neural Tube Closure.

    PubMed

    Kimura-Yoshida, Chiharu; Mochida, Kyoko; Ellwanger, Kristina; Niehrs, Christof; Matsuo, Isao

    2015-06-01

    During primary neurulation, the separation of a single-layered ectodermal sheet into the surface ectoderm (SE) and neural tube specifies SE and neural ectoderm (NE) cell fates. The mechanisms underlying fate specification in conjunction with neural tube closure are poorly understood. Here, by comparing expression profiles between SE and NE lineages, we observed that uncommitted progenitor cells, expressing stem cell markers, are present in the neural plate border/neural fold prior to neural tube closure. Our results also demonstrated that canonical Wnt and its antagonists, DKK1/KREMEN1, progressively specify these progenitors into SE or NE fates in accord with the progress of neural tube closure. Additionally, SE specification of the neural plate border via canonical Wnt signaling is directed by the grainyhead-like 3 (Grhl3) transcription factor. Thus, we propose that the fate specification of uncommitted progenitors in the neural plate border by canonical Wnt signaling and its downstream effector Grhl3 is crucial for neural tube closure. This study implicates that failure in critical genetic factors controlling fate specification of progenitor cells in the neural plate border/neural fold coordinated with neural tube closure may be potential causes of human neural tube defects. PMID:26288816

  12. Fate Specification of Neural Plate Border by Canonical Wnt Signaling and Grhl3 is Crucial for Neural Tube Closure

    PubMed Central

    Kimura-Yoshida, Chiharu; Mochida, Kyoko; Ellwanger, Kristina; Niehrs, Christof; Matsuo, Isao

    2015-01-01

    During primary neurulation, the separation of a single-layered ectodermal sheet into the surface ectoderm (SE) and neural tube specifies SE and neural ectoderm (NE) cell fates. The mechanisms underlying fate specification in conjunction with neural tube closure are poorly understood. Here, by comparing expression profiles between SE and NE lineages, we observed that uncommitted progenitor cells, expressing stem cell markers, are present in the neural plate border/neural fold prior to neural tube closure. Our results also demonstrated that canonical Wnt and its antagonists, DKK1/KREMEN1, progressively specify these progenitors into SE or NE fates in accord with the progress of neural tube closure. Additionally, SE specification of the neural plate border via canonical Wnt signaling is directed by the grainyhead-like 3 (Grhl3) transcription factor. Thus, we propose that the fate specification of uncommitted progenitors in the neural plate border by canonical Wnt signaling and its downstream effector Grhl3 is crucial for neural tube closure. This study implicates that failure in critical genetic factors controlling fate specification of progenitor cells in the neural plate border/neural fold coordinated with neural tube closure may be potential causes of human neural tube defects. PMID:26288816

  13. Cats, frogs, and snakes: early concepts of neural tube defects.

    PubMed

    Obladen, Michael

    2011-11-01

    Disturbed neurulation fascinated scientists of all times. In Egypt, anencephalic infants were venerated as animal-headed gods. Roman law required them to be killed. The medieval world held the mother responsible, either because of assumed imagination or "miswatching," or because of suspected intercourse with animals or devils. Modern embryology and teratology began with the use of the microscope by Malpighi in 1672. Details of neural tube closure were described by Koelliker in 1861 and by His in 1874. From 1822, genetic disease and familial recurrence due to insufficient nutrition were discerned and lower social class identified as a risk factor. It took a century to define the malnutrition as insufficient folate intake. The mandatory supplementation of folate in staple foods successfully reduced the incidence of neural tube defects in the United States, Australia, Canada, and Chile, but it was not adopted by most European countries. PMID:21730342

  14. Neural tube defects – recent advances, unsolved questions and controversies

    PubMed Central

    Copp, Andrew J.; Stanier, Philip; Greene, Nicholas D. E.

    2014-01-01

    Neural tube defects (NTDs) are severe congenital malformations affecting around 1 in every 1000 pregnancies. Here we review recent advances and currently unsolved issues in the NTD field. An innovation in clinical management has come from the demonstration that closure of open spina bifida lesions in utero can diminish neurological dysfunction in children. Primary prevention by folic acid has been enhanced through introduction of mandatory food fortification in some countries, although not yet in UK. Genetic predisposition comprises the majority of NTD risk, and genes that regulate folate one-carbon metabolism and planar cell polarity have been strongly implicated. The sequence of human neural tube closure events remains controversial, but study of mouse NTD models shows that anencephaly, open spina bifida and craniorachischisis result from failure of primary neurulation, while skin-covered spinal dysraphism results from defective secondary neurulation. Other ‘NTD’ malformations, such as encephalocele, are likely to be post-neurulation disorders. PMID:23790957

  15. Antenatal Diagnosis of a Rare Neural Tube Defect: Sincipital Encephalocele

    PubMed Central

    Kehila, Mehdi; Ghades, Sana; Abouda, Hassine Saber; Masmoudi, Aida; Chanoufi, Mohamed Badis

    2015-01-01

    Context. Fetal sincipital encephalocele is one of the most serious congenital neural tube defects with a high risk of mortality and neonatal morbidity. Prenatal diagnosis of this malformation is important in fetal medicine. Case Report. We report a case of prenatal diagnosis of sincipital encephalocele using ultrasound and MRI imaging. The diagnosis was done at 25 weeks of gestation by identifying an anterior cephalic protrusion through a defect in the skull. Conclusion. Through this case, we discuss the differential diagnosis, management, and prognosis of such lesions. PMID:26294989

  16. Slit/Robo1 signaling regulates neural tube development by balancing neuroepithelial cell proliferation and differentiation

    SciTech Connect

    Wang, Guang; Li, Yan; Wang, Xiao-yu; Han, Zhe; Chuai, Manli; Wang, Li-jing; Ho Lee, Kenneth Ka; Geng, Jian-guo; Yang, Xuesong

    2013-05-01

    Formation of the neural tube is the morphological hallmark for development of the embryonic central nervous system (CNS). Therefore, neural tube development is a crucial step in the neurulation process. Slit/Robo signaling was initially identified as a chemo-repellent that regulated axon growth cone elongation, but its role in controlling neural tube development is currently unknown. To address this issue, we investigated Slit/Robo1 signaling in the development of chick neCollege of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH, UKural tube and transgenic mice over-expressing Slit2. We disrupted Slit/Robo1 signaling by injecting R5 monoclonal antibodies into HH10 neural tubes to block the Robo1 receptor. This inhibited the normal development of the ventral body curvature and caused the spinal cord to curl up into a S-shape. Next, Slit/Robo1 signaling on one half-side of the chick embryo neural tube was disturbed by electroporation in ovo. We found that the morphology of the neural tube was dramatically abnormal after we interfered with Slit/Robo1 signaling. Furthermore, we established that silencing Robo1 inhibited cell proliferation while over-expressing Robo1 enhanced cell proliferation. We also investigated the effects of altering Slit/Robo1 expression on Sonic Hedgehog (Shh) and Pax7 expression in the developing neural tube. We demonstrated that over-expressing Robo1 down-regulated Shh expression in the ventral neural tube and resulted in the production of fewer HNK-1{sup +} migrating neural crest cells (NCCs). In addition, Robo1 over-expression enhanced Pax7 expression in the dorsal neural tube and increased the number of Slug{sup +} pre-migratory NCCs. Conversely, silencing Robo1 expression resulted in an enhanced Shh expression and more HNK-1{sup +} migrating NCCs but reduced Pax7 expression and fewer Slug{sup +} pre-migratory NCCs were observed. In conclusion, we propose that Slit/Robo1 signaling is involved in regulating neural tube development by tightly coordinating cell proliferation and differentiation during neurulation. - Highlights: ? The role of Slit/Robo1 signaling was investigated with chick and mouse models. ? Disturbance of Slit/Robo1 signaling resulted in neural tube defects. ? Slit/Robo1 signaling regulated the proliferation of neural tube cells. ? Slit/Robo1 signaling modulated the differentiation of neural tube cells. ? Slit/Robo1 signaling balanced the proliferation and differentiation of neural tube.

  17. Associated anomalies with neural tube defects in fetal autopsies.

    PubMed

    Toru, Havva Serap; Sanhal, Cem Yasar; Uzun, Özlem Ceren; Ocak, Guzide Ayse; Mendilcio?lu, ?nanç; Karaveli, Fatma ?eyda

    2016-03-01

    Neural tube defects (NTD), the consequences of aberrant neural tube closure during embryogenesis, have been mostly investigated in terms of their high prevalence, rate of mortalities and serious morbidities. A proper prenatal outcome counseling of couples coming across a fetal anomaly necessitates the detection and categorization of the primer abnormality, all the co-existing malformations. The aim of this work is to study the incidence and relevance of associated malformations in order to offer a complete pathology report with a true diagnosis. In this study, among 542 fetal autopsy 62 (%11.4) cases with NTD was recorded by the Akdeniz University Pathology Department between January 2006 and June 2012. Twenty (32.4%) NTD cases were associated with anomaly. Twelve cases of associated groups consisted of a congenital syndrome/association, spondylothoracic dysplasia, amniotic band syndrome, Meckel-Gruber syndrome, schisis association. The frequency of associated NTD was 32%, this result was higher than previous reports. NTDs have a significant genetic component to their etiology that interacts with environmental risk factors, which might pose Turkey to be a country with high prevalence of NTD. We want to emphasize that intensive screening, documentation of co-existent abnormalities of NTD, should be conducted in order to exhibit certain diagnosis, to perform proper prenatal genetic counseling of parents for on-going/future pregnancies. PMID:25800566

  18. Birth Prevalence of Neural Tube Defects and Orofacial Clefts in India: A Systematic Review and Meta-Analysis

    PubMed Central

    Allagh, Komal Preet; Shamanna, B. R.; Murthy, Gudlavalleti V. S.; Ness, Andy R.; Doyle, Pat; Neogi, Sutapa B.; Pant, Hira B.

    2015-01-01

    Background In the last two decades, India has witnessed a substantial decrease in infant mortality attributed to infectious disease and malnutrition. However, the mortality attributed to birth defects remains constant. Studies on the prevalence of birth defects such as neural tube defects and orofacial clefts in India have reported inconsistent results. Therefore, we conducted a systematic review of observational studies to document the birth prevalence of neural tube defects and orofacial clefts. Methods A comprehensive literature search for observational studies was conducted in MEDLINE and EMBASE databases using key MeSH terms (neural tube defects OR cleft lip OR cleft palate AND Prevalence AND India). Two reviewers independently reviewed the retrieved studies, and studies satisfying the eligibility were included. The quality of included studies was assessed using selected criteria from STROBE statement. Results The overall pooled birth prevalence (random effect) of neural tube defects in India is 4.5 per 1000 total births (95% CI 4.2 to 4.9). The overall pooled birth prevalence (random effect) of orofacial clefts is 1.3 per 1000 total births (95% CI 1.1 to 1.5). Subgroup analyses were performed by region, time period, consanguinity, and gender of newborn. Conclusion The overall prevalence of neural tube defects from India is high compared to other regions of the world, while that of orofacial clefts is similar to other countries. The majority of studies included in the review were hospital based. The quality of these studies ranged from low to moderate. Further well-designed, high quality community-based observational studies are needed to accurately estimate the burden of neural tube defects and orofacial clefts in India. PMID:25768737

  19. A practical clinical classification of spinal neural tube defects.

    PubMed

    McComb, J Gordon

    2015-10-01

    Current commonly used terminology to describe neural tube defects (NTD) is inconsistent, overlapping, contradictory and, at times, inaccurate making it difficult to convey the nature of the malformation and what needs to be done to optimally treat patients with these congenital abnormalities.NTD can be broadly divided into those that are open with exposed neural tissue and leaking cerebrospinal fluid (CSF) and those that are closed with no exposed neural tissue nor loss of CSF. It appears that the loss of CSF during development is the underlying factor that leads to the entire central nervous system involvement with an open NTD and lack thereof with a closed NTD, wherein only the spinal cord is malformed. There are, however, rare transitional cases that bridge the gap between the two forms.Agreeing on a nomenclature that is used in a standard fashion would be of help in addressing this group of congenital anomalies that have a great deal of variability and, at times, can be quite complex. PMID:26351218

  20. Neural dynamic optimization for control systems. I. Background.

    PubMed

    Seong, C Y; Widrow, B

    2001-01-01

    The paper presents neural dynamic optimization (NDO) as a method of optimal feedback control for nonlinear multi-input-multi-output (MIMO) systems. The main feature of NDO is that it enables neural networks to approximate the optimal feedback solution whose existence dynamic programming (DP) justifies, thereby reducing the complexities of computation and storage problems of the classical methods such as DP. This paper mainly describes the background and motivations for the development of NDO, while the two other subsequent papers of this topic present the theory of NDO and demonstrate the method with several applications including control of autonomous vehicles and of a robot arm, respectively. PMID:18244815

  1. Epidemiology, prenatal management, and prevention of neural tube defects

    PubMed Central

    Salih, Mustafa A.; Murshid, Waleed R.; Seidahmed, Mohammed Z.

    2014-01-01

    This review article discusses the epidemiology, risk factors, prenatal screening, diagnosis, prevention potentials, and epidemiologic impact of neural tube defects (NTDs). The average incidence of NTDs is 1/1000 births, with a marked geographic variation. In the developed countries, the incidence of NTDs has fallen over recent decades. However, it still remains high in the less-developed countries in Latin America, Africa, the Middle East, Asia, and the Far East (>1 to 11/1000 births). Recognized NTDs risks include maternal diabetes, obesity, lower socioeconomic status, hyperthermia, and exposure to certain teratogens during the periconceptional period. Periconceptional folic acid supplementation decreased the prevalence of NTDs by 50-70%, and an obligatory folic acid fortification of food was adopted in several countries to reach women with unplanned pregnancies and those facing social deprivation. Prevention of NTDs can be accelerated if more, especially low income countries, adopted fortification of the staple food in their communities. PMID:25551106

  2. Folate receptor gene variants and neural tube defect occurrence

    SciTech Connect

    Finnell, R.; Greer, K.; Lammer, E.

    1994-09-01

    Recent epidemiological evidence shows that periconceptional use of folic acid supplements may prevent 40-50% of neural tube defects (NTDs). The FDA has subsequently recommended folic acid supplementation of all women of childbearing potential, even though the mechanism by which folic acid prevents NTDs is unknown. We investigated genetic variation of a candidate gene, the 5-methyltetrahydrofolate (5-MeTHF) receptor, that may mediate this preventive effect. The receptor concentrates folate within cells and we have localized its mRNA to neuroepithelial cells during neurulation. Our hypothesis is that dysfunctional 5-MeTHF receptors inadequately concentrate folate intracellularly, predisposing infants to NTDs. We have completed SSCP analysis on 3 of the 4 coding exons of the 5-MeTHF receptor gene of 474 infants participating in a large population-based epidemiological case-control study of NTDs in California; genotyping of another 500 infants is ongoing. Genomic DNA was extracted from residual blood spots from newborn screening samples of cases and controls. Genotyping was done blinded to case status. Polymorphisms have been detected for exons 4 and 5; fourteen percent of the infants have exon 5 polymorphisms. Data will be presented on the prevalence of 5-MeTHF receptor polymorphisms among cases and controls. Relationships among the polymorphisms and NTD occurrence may shed light on how folic acid supplementation prevents NTDs.

  3. RFX7 is required for the formation of cilia in the neural tube

    PubMed Central

    Manojlovic, Zarko; Earwood, Ryan; Kato, Akiko; Stefanovic, Branko; Kato, Yoichi

    2014-01-01

    Regulatory Factor X (RFX) transcription factors are important for development and are likely involved in the pathogenesis of serious human diseases including ciliopathies. While seven RFX genes have been identified in vertebrates and several RFX transcription factors have been reported to be regulators of ciliogenesis, the role of RFX7 in development including ciliogenesis is not known. Here we show that RFX7 in Xenopus laevis is expressed in the neural tube, eye, otic vesicles, and somites. Knockdown of RFX7 in Xenopus embryos resulted in a defect of ciliogenesis in the neural tube and failure of neural tube closure. RFX7 controlled the formation of cilia by regulating the expression of RFX4 gene, which has been reported to be required for ciliogenesis in the neural tube. Moreover, ectopic expression of Foxj1, which is a master regulator of motile cilia formation, suppressed the expression of RFX4 but not RFX7. Taken together, RFX7 plays an important role in the process of neural tube closure at the top of the molecular cascade which controls ciliogenesis in the neural tube. PMID:24530844

  4. RFX7 is required for the formation of cilia in the neural tube.

    PubMed

    Manojlovic, Zarko; Earwood, Ryan; Kato, Akiko; Stefanovic, Branko; Kato, Yoichi

    2014-05-01

    Regulatory Factor X (RFX) transcription factors are important for development and are likely involved in the pathogenesis of serious human diseases including ciliopathies. While seven RFX genes have been identified in vertebrates and several RFX transcription factors have been reported to be regulators of ciliogenesis, the role of RFX7 in development including ciliogenesis is not known. Here we show that RFX7 in Xenopus laevis is expressed in the neural tube, eye, otic vesicles, and somites. Knockdown of RFX7 in Xenopus embryos resulted in a defect of ciliogenesis in the neural tube and failure of neural tube closure. RFX7 controlled the formation of cilia by regulating the expression of RFX4 gene, which has been reported to be required for ciliogenesis in the neural tube. Moreover, ectopic expression of Foxj1, which is a master regulator of motile cilia formation, suppressed the expression of RFX4 but not RFX7. Taken together, RFX7 plays an important role in the process of neural tube closure at the top of the molecular cascade which controls ciliogenesis in the neural tube. PMID:24530844

  5. ACAM, a novel member of the neural IgCAM family, mediates anterior neural tube closure in a primitive chordate.

    PubMed

    Morales Diaz, Heidi; Mejares, Emil; Newman-Smith, Erin; Smith, William C

    2016-01-01

    The neural IgCAM family of cell adhesion molecules, which includes NCAM and related molecules, has evolved via gene duplication and alternative splicing to allow for a wide range of isoforms with distinct functions and homophilic binding properties. A search for neural IgCAMs in ascidians (Ciona intestinalis, Ciona savignyi, and Phallusia mammillata) has identified a novel set of truncated family members that, unlike the known members, lack fibronectin III domains and consist of only repeated Ig domains. Within the tunicates this form appears to be unique to the ascidians, and it was designated ACAM, for Ascidian Cell Adhesion Molecule. In C. intestinalis ACAM is expressed in the developing neural plate and neural tube, with strongest expression in the anterior sensory vesicle precursor. Unlike the two other conventional neural IgCAMs in C. intestinalis, which are expressed maternally and throughout the morula and blastula stages, ACAM expression initiates at the gastrula stage. Moreover, C. intestinalis ACAM is a target of the homeodomain transcription factor OTX, which plays an essential role in the development of the anterior central nervous system. Morpholino (MO) knockdown shows that ACAM is required for neural tube closure. In MO-injected embryos neural tube closure was normal caudally, but the anterior neuropore remained open. A similar phenotype was seen with overexpression of a secreted version of ACAM. The presence of ACAM in ascidians highlights the diversity of this gene family in morphogenesis and neurodevelopment. PMID:26542009

  6. Fate-mapping the mouse neural tube by Cre-loxP transgenesis

    E-print Network

    Richardson, William D.

    nervous system (CNS) develops from a thin layer of neuroepithelial stem cells that form the early neural1 Fate-mapping the mouse neural tube by Cre-loxP transgenesis Matthew Hugh Fogarty The Wolfson in part fulfilment of the degree of Doctor of Philosophy January 2006 #12;2 Abstract The mammalian central

  7. Misexpression of BRE gene in the developing chick neural tube affects neurulation and somitogenesis

    PubMed Central

    Wang, Guang; Li, Yan; Wang, Xiao-Yu; Chuai, Manli; Yeuk-Hon Chan, John; Lei, Jian; Münsterberg, Andrea; Lee, Kenneth Ka Ho; Yang, Xuesong

    2015-01-01

    The brain and reproductive expression (BRE) gene is expressed in numerous adult tissues and especially in the nervous and reproductive systems. However, little is known about BRE expression in the developing embryo or about its role in embryonic development. In this study, we used in situ hybridization to reveal the spatiotemporal expression pattern for BRE in chick embryo during development. To determine the importance of BRE in neurogenesis, we overexpressed BRE and also silenced BRE expression specifically in the neural tube. We established that overexpressing BRE in the neural tube indirectly accelerated Pax7+ somite development and directly increased HNK-1+ neural crest cell (NCC) migration and TuJ-1+ neurite outgrowth. These altered morphogenetic processes were associated with changes in the cell cycle of NCCs and neural tube cells. The inverse effect was obtained when BRE expression was silenced in the neural tube. We also determined that BMP4 and Shh expression in the neural tube was affected by misexpression of BRE. This provides a possible mechanism for how altering BRE expression was able to affect somitogenesis, neurogenesis, and NCC migration. In summary, our results demonstrate that BRE plays an important role in regulating neurogenesis and indirectly somite differentiation during early chick embryo development. PMID:25568339

  8. Introduction Anteroposterior (AP) patterning of the developing neural tube

    E-print Network

    Blumberg, Bruce

    in Spemann's Organizer such as noggin, follistatin or chordin become neuralized in the absence of mesoderm signaling such as noggin, chordin, cerberus, follistatin and dickkopf during gastrulation (reviewed

  9. Novel Mode of Defective Neural Tube Closure in the Non-Obese Diabetic (NOD) Mouse Strain

    PubMed Central

    Salbaum, J. Michael; Kruger, Claudia; MacGowan, Jacalyn; Herion, Nils J.; Burk, David; Kappen, Claudia

    2015-01-01

    Failure to close the neural tube results in birth defects, with severity ranging from spina bifida to lethal anencephaly. Few genetic risk factors for neural tube defects are known in humans, highlighting the critical role of environmental risk factors, such as maternal diabetes. Yet, it is not well understood how altered maternal metabolism interferes with embryonic development, and with neurulation in particular. We present evidence from two independent mouse models of diabetic pregnancy that identifies impaired migration of nascent mesodermal cells in the primitive streak as the morphogenetic basis underlying the pathogenesis of neural tube defects. We conclude that perturbed gastrulation not only explains the neurulation defects, but also provides a unifying etiology for the broad spectrum of congenital malformations in diabetic pregnancies. PMID:26593875

  10. Role of Rab11 in planar cell polarity and apical constriction during vertebrate neural tube closure.

    PubMed

    Ossipova, Olga; Kim, Kyeongmi; Lake, Blue B; Itoh, Keiji; Ioannou, Andriani; Sokol, Sergei Y

    2014-01-01

    Epithelial folding is a critical process underlying many morphogenetic events including vertebrate neural tube closure, however, its spatial regulation is largely unknown. Here we show that during neural tube formation Rab11-positive recycling endosomes acquire bilaterally symmetric distribution in the Xenopus neural plate, being enriched at medial apical cell junctions. This mediolateral polarization was under the control of planar cell polarity (PCP) signalling, was necessary for neural plate folding and was accompanied by the polarization of the exocyst component Sec15. Our further experiments demonstrate that similar PCP-dependent polarization of Rab11 is essential for ectopic apical constriction driven by the actin-binding protein Shroom and during embryonic wound repair. We propose that anisotropic membrane trafficking has key roles in diverse morphogenetic behaviours of individual cells and propagates in a tissue by a common mechanism that involves PCP. PMID:24818582

  11. Syndecan 4 interacts genetically with Vangl2 to regulate neural tube closure and planar cell polarity

    PubMed Central

    Escobedo, Noelia; Contreras, Osvaldo; Muñoz, Rosana; Farías, Marjorie; Carrasco, Héctor; Hill, Charlotte; Tran, Uyen; Pryor, Sophie E.; Wessely, Oliver; Copp, Andrew J.; Larraín, Juan

    2013-01-01

    Syndecan 4 (Sdc4) is a cell-surface heparan sulfate proteoglycan (HSPG) that regulates gastrulation, neural tube closure and directed neural crest migration in Xenopus development. To determine whether Sdc4 participates in Wnt/PCP signaling during mouse development, we evaluated a possible interaction between a null mutation of Sdc4 and the loop-tail allele of Vangl2. Sdc4 is expressed in multiple tissues, but particularly in the non-neural ectoderm, hindgut and otic vesicles. Sdc4;Vangl2Lp compound mutant mice have defective spinal neural tube closure, disrupted orientation of the stereocilia bundles in the cochlea and delayed wound healing, demonstrating a strong genetic interaction. In Xenopus, co-injection of suboptimal amounts of Sdc4 and Vangl2 morpholinos resulted in a significantly greater proportion of embryos with defective neural tube closure than each individual morpholino alone. To probe the mechanism of this interaction, we overexpressed or knocked down Vangl2 function in HEK293 cells. The Sdc4 and Vangl2 proteins colocalize, and Vangl2, particularly the Vangl2Lp mutant form, diminishes Sdc4 protein levels. Conversely, Vangl2 knockdown enhances Sdc4 protein levels. Overall HSPG steady-state levels were regulated by Vangl2, suggesting a molecular mechanism for the genetic interaction in which Vangl2Lp/+ enhances the Sdc4-null phenotype. This could be mediated via heparan sulfate residues, as Vangl2Lp/+ embryos fail to initiate neural tube closure and develop craniorachischisis (usually seen only in Vangl2Lp/Lp) when cultured in the presence of chlorate, a sulfation inhibitor. These results demonstrate that Sdc4 can participate in the Wnt/PCP pathway, unveiling its importance during neural tube closure in mammalian embryos. PMID:23760952

  12. Looking for causes of neural tube defects: where does the environment fit in?

    PubMed Central

    Sever, L E

    1995-01-01

    The neural tube defects anencephaly and spina bifida are important causes of infant mortality and morbidity. Recent studies suggest that many of these defects can be prevented by the periconceptional use of folic acid. At the same time, we do not know what causes most cases of neural tube defects and there is evidence to suggest that they are etiologically heterogeneous. Additional research needs to be directed toward the role of occupational and environmental exposures in the etiology of these defects. Importantly, studies need to examine embryologically and anatomically specific types of defects and develop accurate information on biologically relevant exposures. Exposures toward which attention needs to be directed include organic solvents; agricultural chemicals, including pesticides; water nitrates; heavy metals such as mercury; ionizing radiation; and water disinfection by products. We also recommend that additional attention be paid to mechanisms of neural tube closure and to the potential role of genetic heterogeneity in the absorption and metabolism of xenobiotics and in their effects on the neural tube. PMID:8549468

  13. Epidemiologic and Genetic Aspects of Spina Bifida and Other Neural Tube Defects

    ERIC Educational Resources Information Center

    Au, Kit Sing; Ashley-Koch, Allison; Northrup, Hope

    2010-01-01

    The worldwide incidence of neural tube defects (NTDs) ranges from 1.0 to 10.0 per 1,000 births with almost equal frequencies between two major categories: anencephaly and spina bifida (SB). Epidemiological studies have provided valuable insight for (a) researchers to identify nongenetic and genetic factors contributing to etiology, (b) public…

  14. Fetotoxicity and neural tube defects in CD1 mice exposed to the mycotoxin Fumonisin B1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumonisins are mycotoxins that are produced by Fusarium verticillioides and that occur in corn and corn-based foods. Their effects on human health are unclear, however, epidemiological and experimental evidence suggests that they increase the risk of neural tube defects (NTDs) in populations routine...

  15. Maternal fumonisin exposure as a risk factor for neural tube defects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumonisins are mycotoxins produced by the fungus F. verticillioides, a common contaminant of maize (corn) worldwide. Maternal consumption of fumonisin B1-contaminated maize during early pregnancy has recently been associated with increased risk for neural tube defects (NTDs) in human populations th...

  16. Placental and neural tube defects after maternal fumonisin or FRY720 exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumonisin B1 (FB1) is a mycotoxin produced by a common fungal contaminant of maize. Increased neural tube defect (NTD) risk is observed in human populations that rely heavily on maize as a dietary staple. FB1 inhibition of ceramide synthase results in elevated sphingoid bases. FTY720 is a sphingoid ...

  17. Lipid mediators link cells progression with placental and neural tube defects after maternal fumonisin exposure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumonisin B1 (FB1) is a mycotoxin produced by a common fungal contaminant of maize. Increased risk for neural tube defects (NTDs) is observed in populations that rely on maize as a dietary staple. FB1 inhibits ceramide synthase, resulting in altered pools of biologically active sphingolipids. FB1...

  18. 21 CFR 101.79 - Health claims: Folate and neural tube defects.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... defects—(1) Definition. Neural tube defects are serious birth defects of the brain or spinal cord that can... defects result from failure of closure of the covering of the brain or spinal cord during early embryonic... defects spina bifida or anencephaly,” “birth defects of the brain or spinal cord anencephaly or...

  19. 21 CFR 101.79 - Health claims: Folate and neural tube defects.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... defects—(1) Definition. Neural tube defects are serious birth defects of the brain or spinal cord that can... defects result from failure of closure of the covering of the brain or spinal cord during early embryonic... defects spina bifida or anencephaly,” “birth defects of the brain or spinal cord anencephaly or...

  20. 21 CFR 101.79 - Health claims: Folate and neural tube defects.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... defects—(1) Definition. Neural tube defects are serious birth defects of the brain or spinal cord that can... defects result from failure of closure of the covering of the brain or spinal cord during early embryonic... defects spina bifida or anencephaly,” “birth defects of the brain or spinal cord anencephaly or...

  1. Identification of sensitivity genes involved in teratogen-induced neural tube defects 

    E-print Network

    Hayes, Blaine G

    2013-02-22

    Neural tube defects (NTDs) are common human congenital anomalies affecting 1 per 1000 live-born infants in the United States. NTDs are medical conditions that result from improper formation of the brain and spinal cord. There is evidence to suggest...

  2. Cellular basis of neuroepithelial bending during mouse spinal neural tube closure

    PubMed Central

    McShane, Suzanne G.; Molè, Matteo A.; Savery, Dawn; Greene, Nicholas D. E; Tam, Patrick P.L.; Copp, Andrew J.

    2015-01-01

    Summary Bending of the neural plate at paired dorsolateral hinge points (DLHPs) is required for neural tube closure in the spinal region of the mouse embryo. As a step towards understanding the morphogenetic mechanism of DLHP development, we examined variations in neural plate cellular architecture and proliferation during closure. Neuroepithelial cells within the median hinge point (MHP) contain nuclei that are mainly basally located and undergo relatively slow proliferation, with a 7 h cell cycle length. In contrast, cells in the dorsolateral neuroepithelium, including the DLHP, exhibit nuclei distributed throughout the apico-basal axis and undergo rapid proliferation, with a 4 h cell cycle length. As the neural folds elevate, cell numbers increase to a greater extent in the dorsolateral neural plate that contacts the surface ectoderm, compared with the more ventromedial neural plate where cells contact paraxial mesoderm and notochord. This marked increase in dorsolateral cell number cannot be accounted for solely on the basis of enhanced cell proliferation in this region. We hypothesised that neuroepithelial cells may translocate in a ventral-to-dorsal direction as DLHP formation occurs, and this was confirmed by vital cell labelling in cultured embryos. The translocation of cells into the neural fold, together with its more rapid cell proliferation, leads to an increase in cell density dorsolaterally compared with the more ventromedial neural plate. These findings suggest a model in which DLHP formation may proceed through ‘buckling’ of the neuroepithelium at a dorso-ventral boundary marked by a change in cell-packing density. PMID:26079577

  3. Cellular basis of neuroepithelial bending during mouse spinal neural tube closure.

    PubMed

    McShane, Suzanne G; Molè, Matteo A; Savery, Dawn; Greene, Nicholas D E; Tam, Patrick P L; Copp, Andrew J

    2015-08-15

    Bending of the neural plate at paired dorsolateral hinge points (DLHPs) is required for neural tube closure in the spinal region of the mouse embryo. As a step towards understanding the morphogenetic mechanism of DLHP development, we examined variations in neural plate cellular architecture and proliferation during closure. Neuroepithelial cells within the median hinge point (MHP) contain nuclei that are mainly basally located and undergo relatively slow proliferation, with a 7 h cell cycle length. In contrast, cells in the dorsolateral neuroepithelium, including the DLHP, exhibit nuclei distributed throughout the apico-basal axis and undergo rapid proliferation, with a 4 h cell cycle length. As the neural folds elevate, cell numbers increase to a greater extent in the dorsolateral neural plate that contacts the surface ectoderm, compared with the more ventromedial neural plate where cells contact paraxial mesoderm and notochord. This marked increase in dorsolateral cell number cannot be accounted for solely on the basis of enhanced cell proliferation in this region. We hypothesised that neuroepithelial cells may translocate in a ventral-to-dorsal direction as DLHP formation occurs, and this was confirmed by vital cell labelling in cultured embryos. The translocation of cells into the neural fold, together with its more rapid cell proliferation, leads to an increase in cell density dorsolaterally compared with the more ventromedial neural plate. These findings suggest a model in which DLHP formation may proceed through 'buckling' of the neuroepithelium at a dorso-ventral boundary marked by a change in cell-packing density. PMID:26079577

  4. Cell cycle-related genes p57kip2, Cdk5 and Spin in the pathogenesis of neural tube defects

    PubMed Central

    Li, Xinjun; Yang, Zhong; Zeng, Yi; Xu, Hong; Li, Hongli; Han, Yangyun; Long, Xiaodong; You, Chao

    2013-01-01

    In the field of developmental neurobiology, accurate and ordered regulation of the cell cycle and apoptosis are crucial factors contributing to the normal formation of the neural tube. Preliminary studies identified several genes involved in the development of neural tube defects. In this study, we established a model of developmental neural tube defects by administration of retinoic acid to pregnant rats. Gene chip hybridization analysis showed that genes related to the cell cycle and apoptosis, signal transduction, transcription and translation regulation, energy and metabolism, heat shock, and matrix and cytoskeletal proteins were all involved in the formation of developmental neural tube defects. Among these, cell cycle-related genes were predominant. Retinoic acid ment caused differential expression of three cell cycle-related genes p57kip2, Cdk5 and Spin, the expression levels of which were downregulated by retinoic acid and upregulated during normal neural tube formation. The results of this study indicate that cell cycle-related genes play an important role in the formation of neural tube defects. P57kip2, Cdk5 and Spin may be critical genes in the pathogenesis of neural tube defects. PMID:25206495

  5. Progressive Differentiation and Instructive Capacities of Amniotic Fluid and Cerebrospinal Fluid Proteomes following Neural Tube Closure.

    PubMed

    Chau, Kevin F; Springel, Mark W; Broadbelt, Kevin G; Park, Hye-Yeon; Topal, Salih; Lun, Melody P; Mullan, Hillary; Maynard, Thomas; Steen, Hanno; LaMantia, Anthony S; Lehtinen, Maria K

    2015-12-21

    After neural tube closure, amniotic fluid (AF) captured inside the neural tube forms the nascent cerebrospinal fluid (CSF). Neuroepithelial stem cells contact CSF-filled ventricles, proliferate, and differentiate to form the mammalian brain, while neurogenic placodes, which generate cranial sensory neurons, remain in contact with the AF. Using in vivo ultrasound imaging, we quantified the expansion of the embryonic ventricular-CSF space from its inception. We developed tools to obtain pure AF and nascent CSF, before and after neural tube closure, and to define how the AF and CSF proteomes diverge during mouse development. Using embryonic neural explants, we demonstrate that age-matched fluids promote Sox2-positive neurogenic identity in developing forebrain and olfactory epithelia. Nascent CSF also stimulates SOX2-positive self-renewal of forebrain progenitor cells, some of which is attributable to LIFR signaling. Our Resource should facilitate the investigation of fluid-tissue interactions during this highly vulnerable stage of early brain development. PMID:26702835

  6. Distinct Regulatory Mechanisms Act to Establish and Maintain Pax3 Expression in the Developing Neural Tube

    PubMed Central

    Moore, Steven; Ribes, Vanessa; Terriente, Javier; Wilkinson, David; Relaix, Frédéric; Briscoe, James

    2013-01-01

    Pattern formation in developing tissues is driven by the interaction of extrinsic signals with intrinsic transcriptional networks that together establish spatially and temporally restricted profiles of gene expression. How this process is orchestrated at the molecular level by genomic cis-regulatory modules is one of the central questions in developmental biology. Here we have addressed this by analysing the regulation of Pax3 expression in the context of the developing spinal cord. Pax3 is induced early during neural development in progenitors of the dorsal spinal cord and is maintained as pattern is subsequently elaborated, resulting in the segregation of the tissue into dorsal and ventral subdivisions. We used a combination of comparative genomics and transgenic assays to define and dissect several functional cis-regulatory modules associated with the Pax3 locus. We provide evidence that the coordinated activity of two modules establishes and refines Pax3 expression during neural tube development. Mutational analyses of the initiating element revealed that in addition to Wnt signaling, Nkx family homeodomain repressors restrict Pax3 transcription to the presumptive dorsal neural tube. Subsequently, a second module mediates direct positive autoregulation and feedback to maintain Pax3 expression. Together, these data indicate a mechanism by which transient external signals are converted into a sustained expression domain by the activities of distinct regulatory elements. This transcriptional logic differs from the cross-repression that is responsible for the spatiotemporal patterns of gene expression in the ventral neural tube, suggesting that a variety of circuits are deployed within the neural tube regulatory network to establish and elaborate pattern formation. PMID:24098141

  7. Epidémiologie et facteurs de risque des anomalies de fermeture du tube neural: données marocaines

    PubMed Central

    Radouani, Mohammed Amine; Chahid, Naima; Benmiloud, Loubna; Elammari, Laila; Lahlou, Khalid; Barkat, Amina

    2015-01-01

    Introduction Les anomalies de fermeture du tube neural sont des défauts congénitaux de la formation du système nerveux central. L'incidence varie entre 3 et 40 cas pour 10000 dans le monde. Il existe des facteurs de risque de survenue de cette affection. La prévention reste un élément important dans la prise en charge. L'objectif de ceete étude est d’étudier les paramètres sociodémographiques, maternels, obstétricaux et néonatals des anomalies de fermeture du tube neural et analyser les facteurs de risque responsables dans notre contexte. Méthodes Etude prospective cas-témoin sur 4 ans. Ont été recrutés tous les cas portant une malformation du tube neural isolée ou associée à d'autres malformations. Les données maternelles, obstétricales et néonatales ont été enregistrées. L'analyse statistique était réalisée par le biais d'un logiciel de statistiques SPSS version 17.0 pour Windows. Résultats Soixante huit cas ont été inclus. Quatre-vingts cinq pour cent des malformations étaient isolées. L'anencéphalie était l'anomalie la plus retrouvée (67%). L’âge maternel moyen était 31,03±7,50 ans. La consanguinité parentale était notée dans 9 cas. Un niveau socio-économique bas et un non suivi des grossesses ont été rapportés dans 29% des cas. L’étude a retrouvé des antécédents de mort-nés et de morts néonatales dans 4% des cas. La consommation de Fenugrec était significativement associée aux malformations du tube neural et a été retrouvée dans 8 cas contre 1 cas dans le groupe sain. La voie haute d'accouchement était utilisée dans 29% des cas. L’âge gestationnel moyen était de 35,55±4,16 semaines d'aménorrhée. Il n'y avait pas de prédominance de sexe. On avait noté une relation significative entre les malformations du tube neural et l'avènement d'une asphyxie périnatale, 15 cas présentaient un apgar à 0 à la première minute et 12 cas un apgar inférieur à 7 à la cinquième minute. Conclusion Le bas niveau socio-économique, le non suivi des grossesses et la consommation maternelle de fenugrec en période gestationnelle étaient des facteurs prédictifs de développement d'anomalies du tube neural dans notre contexte.

  8. The Hectd1 Ubiquitin Ligase is Required for Development of the Head Mesenchyme and Neural Tube Closure

    PubMed Central

    Zohn, Irene E.; Anderson, Kathryn V.; Niswander, Lee

    2009-01-01

    Closure of the cranial neural tube depends on normal development of the head mesenchyme. Homozygous-mutant embryos for the ENU-induced open mind (opm) mutation exhibit exencephaly associated with defects in head mesenchyme development and dorsal-lateral hinge point formation. The head mesenchyme in opm mutant embryos is denser than in wildtype embryos and displays an abnormal cellular organization. Since cells that originate from both the cephalic paraxial mesoderm and the neural crest populate the head mesenchyme, we explored the origin of the abnormal head mesenchyme. opm mutant embryos show apparently normal development of neural crest-derived structures. Furthermore, the abnormal head mesenchyme in opm mutant embryos is not derived from the neural crest, but instead expresses molecular markers of cephalic mesoderm. We also report the identification of the opm mutation in the ubiquitously expressed Hectd1 E3 ubiquitin ligase. Two different Hectd1 alleles cause incompletely penetrant neural tube defects in heterozygous animals, indicating that Hectd1 function is required at a critical threshold for neural tube closure. This low penetrance of neural tube defects in embryos heterozygous for Hectd1 mutations suggests that Hectd1 should be considered as candidate susceptibility gene in human neural tube defects. PMID:17442300

  9. Folic Acid for the Prevention of Infant Neural Tube Defects: U.S. Preventive Services Task Force Recommendation

    MedlinePLUS

    Annals of Internal Medicine Summaries for Patients Folic Acid for the Prevention of Infant Neural Tube Defects: U.S. Preventive Services Task Force Recommendation Summaries for Patients are a service provided by Annals ...

  10. CDC Grand Rounds: additional opportunities to prevent neural tube defects with folic acid fortification.

    PubMed

    2010-08-13

    Neural tube defects (NTDs) are serious birth defects that result from the failure of the neural tube to close in the cranial region (anencephaly) or more caudally along the spine (spina bifida) by the 28th day of gestation. Infants born with anencephaly usually die within a few days of birth, and those with spina bifida have life-long disabilities with varying degrees of paralysis. Currently, identified risk factors for NTDs include a mother who previously had an NTD-affected pregnancy, maternal diabetes, obesity, hyperthermia, certain antiseizure medications, genetic variants, race/ethnicity, and nutrition (particularly folic acid insufficiency). In the United States, during 1995-1996, approximately 4,000 pregnancies were affected by an NTD. This number declined to 3,000 pregnancies in 1999-2000 after fortification of enriched cereal grain products with folic acid was mandated. Worldwide, in 1998, approximately 300,000 births were affected by an NTD. PMID:20703205

  11. Prevention of neural tube defects with folic acid: The Chinese experience

    PubMed Central

    Ren, Ai-Guo

    2015-01-01

    Neural tube defects (NTDs) are a group of congenital malformations of the central nervous system that are caused by the closure failure of the embryonic neural tube by the 28th day of conception. Anencephaly and spina bifida are the two major subtypes. Fetuses with anencephaly are often stillborn or electively aborted due to prenatal diagnosis, or they die shortly after birth. Most infants with spina bifida are live-born and, with proper surgical treatment, can survive into adulthood. However, these children often have life-long physical disabilities. China has one of the highest prevalence of NTDs in the world. Inadequate dietary folate intake is believed to be the main cause of the cluster. Unlike many other countries that use staple fortification with folic acid as the public health strategy to prevent NTDs, the Chinese government provides all women who have a rural household registration and who plan to become pregnant with folic acid supplements, free of charge, through a nation-wide program started in 2009. Two to three years after the initiation of the program, the folic acid supplementation rate increased to 85% in the areas of the highest NTD prevalence. The mean plasma folate level of women during early and mid-pregnancy doubled the level before the program was introduced. However, most women began taking folic acid supplements when they knew that they were pregnant. This is too late for the protection of the embryonic neural tube. In a post-program survey of the women who reported folic acid supplementation, less than a quarter of the women began taking supplements prior to pregnancy, indicating that the remaining three quarters of the fetuses remained unprotected during the time of neural tube formation. Therefore, staple food fortification with folic acid should be considered as a priority in the prevention of NTDs. PMID:26261765

  12. Prevention of neural tube defects with folic acid: The Chinese experience.

    PubMed

    Ren, Ai-Guo

    2015-08-01

    Neural tube defects (NTDs) are a group of congenital malformations of the central nervous system that are caused by the closure failure of the embryonic neural tube by the 28(th) day of conception. Anencephaly and spina bifida are the two major subtypes. Fetuses with anencephaly are often stillborn or electively aborted due to prenatal diagnosis, or they die shortly after birth. Most infants with spina bifida are live-born and, with proper surgical treatment, can survive into adulthood. However, these children often have life-long physical disabilities. China has one of the highest prevalence of NTDs in the world. Inadequate dietary folate intake is believed to be the main cause of the cluster. Unlike many other countries that use staple fortification with folic acid as the public health strategy to prevent NTDs, the Chinese government provides all women who have a rural household registration and who plan to become pregnant with folic acid supplements, free of charge, through a nation-wide program started in 2009. Two to three years after the initiation of the program, the folic acid supplementation rate increased to 85% in the areas of the highest NTD prevalence. The mean plasma folate level of women during early and mid-pregnancy doubled the level before the program was introduced. However, most women began taking folic acid supplements when they knew that they were pregnant. This is too late for the protection of the embryonic neural tube. In a post-program survey of the women who reported folic acid supplementation, less than a quarter of the women began taking supplements prior to pregnancy, indicating that the remaining three quarters of the fetuses remained unprotected during the time of neural tube formation. Therefore, staple food fortification with folic acid should be considered as a priority in the prevention of NTDs. PMID:26261765

  13. TWIST1: a subtle modulator of neural differentiation and neural tube formation 

    E-print Network

    Nistor, Paul Andrei

    2013-07-06

    The central nervous system is formed from epiblast precursor cells through Neurulation. Neural induction can be studied in its main aspects in vitro. However, the process is poorly understood, especially in regard to ...

  14. [The effect of folic acid fortification on the reduction of neural tube defects].

    PubMed

    Santos, Leonor Maria Pacheco; Pereira, Michelle Zanon

    2007-01-01

    Neural tube defects are congenital malformations that occur during initial fetal development, leading to anencephaly and spina bifida; folic acid deficiency is the most important risk factor identified to date. Brazil has one of the world's highest neural tube defect rates. Food consumption surveys among pregnant Brazilian women showed a high rate of inadequate folic acid intake (< 0.6 mg/day). In 2004, the National Health Surveillance Agency (ANVISA) mandated the fortification of corn meal and wheat flour with folic acid (0.15 mg/100g). The National Family Budget Survey estimated the average amount of bread/flour products available in households as 106.1g/day (contributing with 0.16 mg folic acid/day). However, while in the South of the country the supply was 144 g/day, in the North and Central West it barely reached 70 g/day. Folic acid food fortification is mandatory in some 40 countries, but only four have assessed this strategy. The existing studies have all shown a significant impact, ranging from 19 to 78%. Folic acid fortification is an undeniably important intervention for primary prevention, and neural tube defects can now be considered a preventable epidemic. PMID:17187100

  15. Arsenate-induced maternal glucose intolerance and neural tube defects in a mouse model

    SciTech Connect

    Hill, Denise S.; Wlodarczyk, Bogdan J.; Mitchell, Laura E.; Finnell, Richard H.

    2009-08-15

    Background: Epidemiological studies have linked environmental arsenic (As) exposure to increased type 2 diabetes risk. Periconceptional hyperglycemia is a significant risk factor for neural tube defects (NTDs), the second most common structural birth defect. A suspected teratogen, arsenic (As) induces NTDs in laboratory animals. Objectives: We investigated whether maternal glucose homeostasis disruption was responsible for arsenate-induced NTDs in a well-established dosing regimen used in studies of arsenic's teratogenicity in early neurodevelopment. Methods: We evaluated maternal intraperitoneal (IP) exposure to As 9.6 mg/kg (as sodium arsenate) in LM/Bc/Fnn mice for teratogenicity and disruption of maternal plasma glucose and insulin levels. Selected compounds (insulin pellet, sodium selenate (SS), N-acetyl cysteine (NAC), L-methionine (L-Met), N-tert-Butyl-{alpha}-phenylnitrone (PBN)) were investigated for their potential to mitigate arsenate's effects. Results: Arsenate caused significant glucose elevation during an IP glucose tolerance test (IPGTT). Insulin levels were not different between arsenate and control dams before (arsenate, 0.55 ng/dl; control, 0.48 ng/dl) or after glucose challenge (arsenate, 1.09 ng/dl; control, 0.81 ng/dl). HOMA-IR index was higher for arsenate (3.9) vs control (2.5) dams (p = 0.0260). Arsenate caused NTDs (100%, p < 0.0001). Insulin pellet and NAC were the most successful rescue agents, reducing NTD rates to 45% and 35%. Conclusions: IPGTT, insulin assay, and HOMA-IR results suggest a modest failure of glucose stimulated insulin secretion and insulin resistance characteristic of glucose intolerance. Insulin's success in preventing arsenate-induced NTDs provides evidence that these arsenate-induced NTDs are secondary to elevated maternal glucose. The NAC rescue, which did not restore maternal glucose or insulin levels, suggests oxidative disruption plays a role.

  16. Trehalose prevents neural tube defects by correcting maternal diabetes-suppressed autophagy and neurogenesis.

    PubMed

    Xu, Cheng; Li, Xuezheng; Wang, Fang; Weng, Hongbo; Yang, Peixin

    2013-09-01

    Preexisting maternal diabetes increases the risk of neural tube defects (NTDs). The mechanism underlying maternal diabetes-induced NTDs is not totally defined, and its prevention remains a challenge. Autophagy, an intracellular process to degrade dysfunction protein and damaged cellular organelles, regulates cell proliferation, differentiation, and apoptosis. Because autophagy impairment causes NTDs reminiscent of those observed in diabetic pregnancies, we hypothesize that maternal diabetes-induced autophagy impairment causes NTD formation by disrupting cellular homeostasis, leading to endoplasmic reticulum (ER) stress and apoptosis, and that restoration of autophagy by trehalose, a natural disaccharide, prevents diabetes-induced NTDs. Embryos from nondiabetic and type 1 diabetic mice fed with or without 2 or 5% trehalose water were used to assess markers of autophagy, ER stress, and neurogenesis, numbers of autophagosomes, gene expression that regulates autophagy, NTD rates, indices of mitochondrial dysfunction, and neuroepithelial cell apoptosis. Maternal diabetes suppressed autophagy by significantly reducing LC3-II expression, autophagosome numbers, and GFP-LC3 punctate foci in neuroepithelial cells and by altering autophagy-related gene expression. Maternal diabetes delayed neurogenesis by blocking Sox1 neural progenitor differentiation. Trehalose treatment reversed autophagy impairment and prevented NTDs in diabetic pregnancies. Trehalose resolved homeostatic imbalance by correcting mitochondrial defects, dysfunctional proteins, ER stress, apoptosis, and delayed neurogenesis in the neural tubes exposed to hyperglycemia. Our study demonstrates for the first time that maternal diabetes suppresses autophagy in neuroepithelial cells of the developing neural tube, leading to NTD formation, and provides evidence for the potential efficacy of trehalose as an intervention against hyperglycemia-induced NTDs. PMID:23880312

  17. Systems biological approach to investigate the lack of familial link between Down's Syndrome & Neural Tube Disorders

    PubMed Central

    Ragunath, PK; Abhinand, PA

    2013-01-01

    Systems Biology involves the study of the interactions of biological systems and ultimately their functions. Down's syndrome (DS) is one of the most common genetic disorders which are caused by complete, or occasionally partial, triplication of chromosome 21, characterized by cognitive and language dysfunction coupled with sensory and neuromotor deficits. Neural Tube Disorders (NTDs) are a group of congenital malformations of the central nervous system and neighboring structures related to defective neural tube closure during the first trimester of pregnancy usually occurring between days 18-29 of gestation. Several studies in the past have provided considerable evidence that abnormal folate and methyl metabolism are associated with onset of DS & NTDs. There is a possible common etiological pathway for both NTDs and Down's syndrome. But, various research studies over the years have indicated very little evidence for familial link between the two disorders. Our research aimed at the gene expression profiling of microarray datasets pertaining to the two disorders to identify genes whose expression levels are significantly altered in these conditions. The genes which were 1.5 fold unregulated and having a p-value <0.05 were filtered out and gene interaction network were constructed for both NTDs and DS. The top ranked dense clique for both the disorders were recognized and over representation analysis was carried out for each of the constituent genes. The comprehensive manual analysis of these genes yields a hypothetical understanding of the lack of familial link between DS and NTDs. There were no genes involved with folic acid present in the dense cliques. Only – CBL, EGFR genes were commonly present, which makes the allelic variants of these genes – good candidates for future studies regarding the familial link between DS and NTDs. Abbreviations NTD - Neural Tube Disorders, DS - Down's Syndrome, MTHFR - Methylenetetrahydrofolate reductase, MTRR– 5 - methyltetrahydrofolate-homocysteine methyltransferase reductase. PMID:23904737

  18. Research on the neural networks used for shaping tubes by the liquid extrusion process

    SciTech Connect

    Qi, L.H.; Li, H.J.; Hou, J.J.; Cui, P.L.

    2000-02-01

    Liquid extrusion, as a new kind of metal forming process for shaping tube and bar products directly from liquid metal, can reduce the intermediate steps and production costs and make the materials doubly strengthened. But it has not been widely used since the process parameters are now selected by experience, which can easily result in a high reject rate. In order to analyze the contributing factors of the process, the artificial neural network method was used in this paper. The network architecture was determined by adopting 125 sets of experimental data of the shaping tubes of AlCuSiMg alloy as samples and, by contrast, one or two hidden layers and the numbers of nodes and other network parameters. The knowledge base for the process parameters of liquid extrusion has been established. The values predicted by the knowledge base are very consistent with the practical ones. The result shows that the introduced method is feasible and effective.

  19. [Neural tube defects and folic acid: a historical overview of a highly successful preventive intervention].

    PubMed

    Vásquez, Adriana Ordoñez; Suarez-Obando, Fernando

    2015-12-01

    This article gives a broad overview of part of the historical evolution of medical knowledge about neural tube defects (NTD) and the discovery of vitamin B9 or folic acid, as well as some relevant research events that, over the course of several centuries, defined the relationships between the understanding of central nervous system embryology, the discovery of the vitamin, the correlation between folic acid and cell proliferation and lastly the development of preventive measures for this type of defects. This narrative allows us to examine historically relevant concepts underlying clinical actions with a populational impact that prevent NTDs via folic acid consumption prior to conception. PMID:25650704

  20. METHYLMERCURY INDUCED TOXICOGENOMIC RESPONSE IN C57 AND SWV MOUSE EMBRYOS UNDERGOING NEURAL TUBE CLOSURE

    PubMed Central

    Robinson, Joshua F.; Griffith, William C.; Yu, Xiaozhong; Hong, Sungwoo; Kim, Euvin; Faustman, Elaine M.

    2010-01-01

    Methylmercury (MeHg) is a developmental neurotoxicant and teratogen and is hypothesized to perturb a wide range of biological processes, like other metals including arsenic (As) and cadmium (Cd). Common inbred mouse strains including C57 (sensitive) and SWV (resistant) display differences in sensitivity to metals such as As and Cd when exposed during neurulation. In this study, we investigated the impact of MeHg on neurulation, assessing for potential differences in sensitivity and associated toxicogenomic response in C57 and SWV mouse embryos. Parallel with morphological assessments of neural tube closure, we evaluated quantitative differences in MeHg-induced alterations in expression between strains at the gene level and within gene-enriched biological processes. Specifically, we observed differing sensitivities to MeHg-induced impacts on neural tube closure between C57 and SWV embryos in a time-dependent manner. These observations correlated with greater impact on the expression of genes associated with development and environmental stress-related pathways in the C57 compared to the SWV. Additional developmental parameters (e.g. mortality, growth effects) evaluated showed mixed significant effects across the two strains and did not support observations of differential sensitivity to MeHg. This study provides potential insights into MeHg-induced mechanisms of developmental toxicity, alterations associated with increased MeHg sensitivity and common biological processes affected by metals in embryos undergoing neurulation. PMID:20493249

  1. Neural Tube Defects and Atypical Deletion on 22q11.2

    PubMed Central

    Leoni, Chiara; Stevenson, David A.; Geiersbach, Katherine B.; Paxton, Christian N.; Krock, Bryan L.; Mao, Rong; Rope, Alan F.

    2014-01-01

    The 22q11.2 deletion syndrome (22q11.2DS) is a common microdeletion disorder. Most of the patients show the common 3 Mb deletion but proximal 1.5 Mb deletion and unusual deletions located outside the common deleted region, have been detected particularly with the advance of comparative cytogenomic microarray technologies. The individuals reported in the literature with unusual deletions involving the 22q11 region, showed milder facial phenotypes, decreased incidence of cardiac anomalies and intellectual disability. We describe two sibs with an atypical 0.8 Mb microdeletion of chromosome 22q11 who both showed myelomeningocele and mild facial dysmorphisms. The association between neural tube defect and the clinical diagnosis of Di George anomaly/velocardiofacial syndrome is well documented in the literature, but not all cases had molecular studies to determine breakpoint regions. This report helps to narrow a potential critical region for neural tube defects associated with 22q11 deletions. PMID:25123577

  2. Variants in MTHFR gene and neural tube defects susceptibility in China.

    PubMed

    Wang, Yongxin; Liu, Yuan; Ji, Wenyu; Qin, Hu; Wu, Hao; Xu, Danshu; Turtuohut, Tukebai; Wang, Zengliang

    2015-08-01

    Neural tube defect (NTD) is a severe congenital birth abnormalities involving incomplete neural tube closure. 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene plays key role in folate cycle and methylation cycle, which could affect the DNA synthesis, repair and methylation. In this study, we aim to investigate the correlation between MTHFR polymorphisms and NTD-affected pregnancy. There were 444 participants involved in our study. Tag-SNPs were identified in HapMap Databases. Blood samples were collected from all subjects to further extract the genomic DNAs by TaqMan Blood DNA kits. We also carried out a meta-analysis based on previous published studies to further examine the association between MTHFR polymorphisms and NTD. In case-control study analysis, two SNPs were identified to be associated with NTD risk. The 677 C > T genetic variant was correlated with increased risk of NTD-affected pregnancy. However, the 1298 A > C polymorphism was shown to lower the risk of NTD-affected pregnancy. The protective role of 1298 A > C polymorphisms was further supported by the result of meta-analysis. Our study revealed that the SNPs of 677C > T and 1298A > C in MTHFR were associated with NTD-affected pregnancy, in which 677C > T was a risk factor and in contrast 1298A > C was protective factor against NTD. Our results of meta-analysis also revealed the 1298A > C MTHFR polymorphism play protective role in NTD. PMID:25855017

  3. Primary cilium and sonic hedgehog signaling during neural tube patterning: role of GPCRs and second messengers.

    PubMed

    Pal, Kasturi; Mukhopadhyay, Saikat

    2015-04-01

    The ventral neural tube in vertebrates is patterned by a gradient of sonic hedgehog (Shh) secreted from the notochord and floor plate. Forward genetic screens first pointed to the role of the primary cilium in ventral neural tube patterning. Further research has shown that most components of the Shh pathway localize to or shuttle through the primary cilium. In the absence of Shh, the bifunctional Gli transcription factors are proteolytically processed into repressor forms in a protein kinase A (PKA)- and cilium-dependent manner. Recent work suggests that the orphan G-protein-coupled receptor (GPCR) Gpr161 localizes to cilia, and functions as a negative regulator of Shh signaling by determining Gli processing via cAMP signaling. The primary cilium also functions as a signaling compartment for calcium in the Shh pathway. A better understanding of the role of the cilium as a signaling compartment, and the interplay of second messenger systems that regulate PKA activation and Gli amplification during signaling is critical for deciphering the role of Shh during development, neuronal differentiation, and tumorigenesis. PMID:24863049

  4. Neural Plasticity in Multiple Sclerosis: The Functional and Molecular Background

    PubMed Central

    Ksiazek-Winiarek, Dominika Justyna; Szpakowski, Piotr; Glabinski, Andrzej

    2015-01-01

    Multiple sclerosis is an autoimmune neurodegenerative disorder resulting in motor dysfunction and cognitive decline. The inflammatory and neurodegenerative changes seen in the brains of MS patients lead to progressive disability and increasing brain atrophy. The most common type of MS is characterized by episodes of clinical exacerbations and remissions. This suggests the presence of compensating mechanisms for accumulating damage. Apart from the widely known repair mechanisms like remyelination, another important phenomenon is neuronal plasticity. Initially, neuroplasticity was connected with the developmental stages of life; however, there is now growing evidence confirming that structural and functional reorganization occurs throughout our lifetime. Several functional studies, utilizing such techniques as fMRI, TBS, or MRS, have provided valuable data about the presence of neuronal plasticity in MS patients. CNS ability to compensate for neuronal damage is most evident in RR-MS; however it has been shown that brain plasticity is also preserved in patients with substantial brain damage. Regardless of the numerous studies, the molecular background of neuronal plasticity in MS is still not well understood. Several factors, like IL-1?, BDNF, PDGF, or CB1Rs, have been implicated in functional recovery from the acute phase of MS and are thus considered as potential therapeutic targets. PMID:26229689

  5. Different Epigenetic Alterations Are Associated with Abnormal IGF2/Igf2 Upregulation in Neural Tube Defects

    PubMed Central

    Bai, Baoling; Zhang, Qin; Liu, Xiaozhen; Miao, Chunyue; Shangguan, Shaofang; Bao, Yihua; Guo, Jin; Wang, Li; Zhang, Ting; Li, Huili

    2014-01-01

    The methylation status of DNA methylation regions (DMRs) of the imprinted gene IGF2/Igf2 is associated with neural tube defects (NTDs), which are caused by a failure of the neural tube to fold and close and are the second-most common birth defect; however, the characterization of the expression level of IGF2/Igf2 in neural tissue from human fetuses affected with NTDs remains elusive. More importantly, whether abnormal chromatin structure also influences IGF2/Igf2 expression in NTDs is unclear. Here, we investigated the transcriptional activity of IGF2/Igf2 in normal and NTD spinal cord tissues, the methylation status of different DMRs, and the chromatin structure of the promoter. Our data indicated that in NTD samples from both human fetuses and retinoic acid (RA)-treated mouse fetuses, the expression level of IGF2/Igf2 was upregulated 6.41-fold and 1.84-fold, respectively, compared to controls. H19 DMR1, but not IGF2 DMR0, was hypermethylated in human NTD samples. In NTD mice, h19 DMR1 was stable, whereas the chromatin structure around the promoter of Igf2 might be loosened, which was displayed by higher H3K4 acetylation and lower H3K27 trimethylation. Therefore, the data revealed that IGF2/Igf2 expression can be ectopically up-regulated by dual epigenetic factors in NTDs. In detail, the upregulation of IGF2/Igf2 is likely controlled by hypermethylation of H19 DMR1 in human NTDs, however, in acute external RA-induced NTD mice it is potentially determined by more open chromatin structure. PMID:25423083

  6. STUDIES ON THE INDUCTION OF NEURAL TUBE DEFECTS IN THE LM/BC AND CD1 MOUSE STRAINS FOLLOWING ORAL OR INTRAPERITONEAL FUMONISIN EXPOSURE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The human health effects of Fusarium verticillioides and fumonisins are uncertain. There is evidence however suggesting that fumonisins disrupt folate utilization and increase the risk of neural tube defects (NTDs = birth defects cause by failure of the neural tube to close properly) in populati...

  7. Melatonin prevents neural tube defects in the offspring of diabetic pregnancy.

    PubMed

    Liu, Shangming; Guo, Yuji; Yuan, Qiuhuan; Pan, Yan; Wang, Liyan; Liu, Qian; Wang, Fuwu; Wang, Jingjing; Hao, Aijun

    2015-11-01

    Melatonin, an endogenous neurohormone secreted by the pineal gland, has a variety of physiological functions and neuroprotective effects. However, its protective role on the neural tube defects (NTDs) was not very clear. The aim of this study was to investigate the effects of melatonin on the incidence of NTDs (including anencephaly, encephalocele, and spina bifida) of offspring from diabetic pregnant mice as well as its underlying mechanisms. Pregnant mice were given 10 mg/kg melatonin by daily i.p. injection from embryonic day (E) 0.5 until being killed on E11.5. Here, we showed that melatonin decreased the NTDs (especially exencephaly) rate of embryos exposed to maternal diabetes. Melatonin stimulated proliferation of neural stem cells (NSCs) under hyperglycemic condition through the extracellular regulated protein kinases (ERK) pathway. Furthermore, as a direct free radical scavenger, melatonin decreased apoptosis of NSCs exposed to hyperglycemia. In the light of these findings, it suggests that melatonin supplementation may play an important role in the prevention of neural malformations in diabetic pregnancy. PMID:26475080

  8. Neural networks technique based signal-from-background separation and design optimization for a W/quartz fiber calorimeter

    E-print Network

    G. Mavromanolakis

    2003-04-24

    We present a signal-from-background separation study based on neural networks technique applied to a W/quartz fiber calorimeter. Performance results in terms of signal efficiency and improvement of the signal-to-background ratio are presented. We conclude that by using neural networks we can efficiently separate signal from background and achieve a signal enhancement over the background of the order of several thousands at high efficiency.

  9. Use of Family History Information for Neural Tube Defect Prevention: Integration into State-Based Recurrence Prevention Programs

    ERIC Educational Resources Information Center

    Green, Ridgely Fisk; Ehrhardt, Joan; Ruttenber, Margaret F.; Olney, Richard S.

    2011-01-01

    A family history of neural tube defects (NTDs) can increase the risk of a pregnancy affected by an NTD. Periconceptional folic acid use decreases this risk. Purpose: Our objective was to determine whether second-degree relatives of NTD-affected children showed differences in folic acid use compared with the general population and to provide them…

  10. Hydrolyzed fumonisin B1 (HFB1) did not induce neural tube defects in LM/Bc mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumonisins are mycotoxins produced by Fusarium verticillioides. They are found in corn-based foods and are toxic and carcinogenic to rodents. There is evidence suggesting that consumption of corn tortillas containing fumonisins contributed to an enigmatic cluster of neural tube defects (NTDs) in s...

  11. Not all cases of neural-tube defect can be prevented by increasing the intake of folic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to evaluate the beneficial effects of different levels of folic acid administration on the prevalence of neural tube defects, with a concurrent assessment of other potential benefits or adverse effects. The evaluation was based on a systematic review of the published ...

  12. Will Increasing Folic Acid in Fortified Grain Products Further Reduce Neural Tube Defects without Causing Harm?: Consideration of the Evidence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Will Increasing Folic Acid in Fortified Grain Products Further Reduce Neural Tube Defects without Causing Harm?: Consideration of the Evidence. In the January issue of this journal, Johnston (1) includes our group’s recent analysis of data from the 1999-2002 National Health and Nutrition Examination...

  13. Increased sphingoid base-1-phosphates and failure of neural tube closure after exposure to fumonisin or FTY720

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumonisin B1 (FB1) is a mycotoxin produced by a common fungal contaminant of corn. Ingestion of FB1-contaminated food is associated with increased risk for neural tube defects (NTDs). FB1 induces NTDs in inbred LM/Bc mice. FB1 inhibits ceramide synthase in de novo sphingolipid biosynthesis, resultin...

  14. GENE-NUTRIENT-ENVIRONMENT INTERACTIONS AS RISK FACTORS FOR BIRTH DEFECTS: FUMONISIN, FOLATE, GENETIC VARIATION AND NEURAL TUBE DEFECTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The second most common birth defect is neural tube defects (NTDs). In Guatemala, parts of China and Africa, NTD risk is estimated to be higher than that observed in the USA. The etiology of NTD in these areas is complex. Increased risk has been associated with genetic predisposition, dietary expo...

  15. Fumonisin as a possible contributing factor to neural tube defects in populations consuming large amounts of maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumonisin B1 (FB) is an inhibitor of sphingolipid (SL) biosynthesis and folate transport and can induce neural tube defects (NTD) in mice. NTD incidence is high in countries where maize is a dietary staple and FB exposure is likely. In Guatemala the incidence of FB in maize has been well documented ...

  16. Syndromes, disorders and maternal risk factors associated with neural tube defects (I).

    PubMed

    Chen, Chih-Ping

    2008-03-01

    Fetuses with neural tube defects (NTDs) may be associated with syndromes, disorders, and maternal risk factors. This article provides a comprehensive review of syndromes, disorders, and maternal risk factors associated with NTDs, such as acrocallosal syndrome, autosomal dominant brachydactyly-clinodactyly syndrome, Manouvrier syndrome, short rib-polydactyly syndrome, Disorganization ( Ds )-like human malformations, isolated hemihyperplasia, X-linked NTDs, meroanencephaly, schisis association, diprosopus, fetal valproate syndrome, DiGeorge syndrome/velocardiofacial syndrome, Waardenburg syndrome, folic acid antagonists, diabetes mellitus, and obesity. NTDs associated with syndromes, disorders, and maternal risk factors are a rare but important cause of NTDs. The recurrence risk and the preventive effect of maternal folic acid intake in NTDs associated with syndromes, disorders, and maternal risk factors may be different from those of non-syndromic multifactorial NTDs. Perinatal identification of NTDs should alert one to the syndromes, disorders, and maternal risk factors associated with NTDs, and prompt a thorough etiologic investigation and genetic counseling. PMID:18400576

  17. Methanol-induced neural tube defects in mice: Characterization of lesions, target and teratogen

    SciTech Connect

    Bolon, B.N.

    1993-01-01

    The present studies investigated the hypothesis that methanol induces neural tube defects (e.g., exenephaly) through the cytotoxic action of its metabolite, formate, upon embryonic neuroepithelium during neurulation. Methanol was tested because of concerns raised by the proposed heavier use of this alcohol in automobile fuels, which could result in increased exposure of the general public. Neurulation (gestational days [GD] 7-9 in mice) was shown to be the period of greatest vulnerability. Pregnant mice inhaled methanol (5,000 to 15,000 ppm) for 6 hr/day either during GD 7-9 or during a encephaly was observed only if exposure to [>=] 10,000 ppm encompassed GD 7 and/or GD 8. Aberrant neural tube closure was confirmed as the pathogensis by demonstrating persistent patency of the anterior neuropore in embryos. Peak concentrations of 431 mmol methanol/kg and 14 mmol formate/kg were measured in embryos following maternal methanol inhalation at a teratogenic level (15,000 ppm for 6 hr on GD 8). Autoradiography of pregnant mice after intravenous injection with 0.06 or 6 mmol [sup 14]C-formate/kg on GD 8 revealed selective localization of radioactivity to the neuroepithelium within 10 minutes after administration, with at least a two fold greater level in each tissue of formate-exposed embryos. Exposure in vitro to either 187 mM methanol or [>=]12 mM formate for 12 hr delayed closure of the anterior neuropore in neurulating mouse embryos. In addition, in vitro exposure to formate resulted in lower reduction of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bormide (MTT) and decreased levels of ATP in cephalic tissues of embryos. Formate also reduced MTT staining in neuroepithelium and mesoderm, suggesting these embryonic tissues as potential targets.

  18. T-type Calcium Channel Regulation of Neural Tube Closure and EphrinA/EPHA Expression.

    PubMed

    Abdul-Wajid, Sarah; Morales-Diaz, Heidi; Khairallah, Stephanie M; Smith, William C

    2015-10-27

    A major class of human birth defects arise from aberrations during neural tube closure (NTC). We report on a NTC signaling pathway requiring T-type calcium channels (TTCCs) that is conserved between primitive chordates (Ciona) and Xenopus. With loss of TTCCs, there is a failure to seal the anterior neural folds. Accompanying loss of TTCCs is an upregulation of EphrinA effectors. Ephrin signaling is known to be important in NTC, and ephrins can affect both cell adhesion and repulsion. In Ciona, ephrinA-d expression is downregulated at the end of neurulation, whereas, with loss of TTCC, ephrinA-d remains elevated. Accordingly, overexpression of ephrinA-d phenocopied TTCC loss of function, while overexpression of a dominant-negative Ephrin receptor was able to rescue NTC in a Ciona TTCC mutant. We hypothesize that signaling through TTCCs is necessary for proper anterior NTC through downregulation of ephrins, and possibly elimination of a repulsive signal. PMID:26489462

  19. Optimal Combination of Neural Temporal Envelope and Fine Structure Cues to Explain Speech Identification in Background Noise

    PubMed Central

    Moon, Il Joon; Won, Jong Ho; Ives, D. Timothy; Nie, Kaibao; Heinz, Michael G.; Lorenzi, Christian; Rubinstein, Jay T.

    2014-01-01

    The dichotomy between acoustic temporal envelope (ENV) and fine structure (TFS) cues has stimulated numerous studies over the past decade to understand the relative role of acoustic ENV and TFS in human speech perception. Such acoustic temporal speech cues produce distinct neural discharge patterns at the level of the auditory nerve, yet little is known about the central neural mechanisms underlying the dichotomy in speech perception between neural ENV and TFS cues. We explored the question of how the peripheral auditory system encodes neural ENV and TFS cues in steady or fluctuating background noise, and how the central auditory system combines these forms of neural information for speech identification. We sought to address this question by (1) measuring sentence identification in background noise for human subjects as a function of the degree of available acoustic TFS information and (2) examining the optimal combination of neural ENV and TFS cues to explain human speech perception performance using computational models of the peripheral auditory system and central neural observers. Speech-identification performance by human subjects decreased as the acoustic TFS information was degraded in the speech signals. The model predictions best matched human performance when a greater emphasis was placed on neural ENV coding rather than neural TFS. However, neural TFS cues were necessary to account for the full effect of background-noise modulations on human speech-identification performance. PMID:25186758

  20. DNA methyltransferase3A as a molecular switch mediating the neural tube-to-neural crest fate transition

    PubMed Central

    Hu, Na; Strobl-Mazzulla, Pablo; Sauka-Spengler, Tatjana; Bronner, Marianne E.

    2012-01-01

    Here, we explore whether silencing via promoter DNA methylation plays a role in neural versus neural crest cell lineage decisions. We show that DNA methyltransferase3A (DNMT3A) promotes neural crest specification by directly mediating repression of neural genes like Sox2 and Sox3. DNMT3A is expressed in the neural plate border, and its knockdown causes ectopic Sox2 and Sox3 expression at the expense of neural crest markers. In vivo chromatin immunoprecipitation of neural folds demonstrates that DNMT3A specifically associates with CpG islands in the Sox2 and Sox3 promoter regions, resulting in their repression by methylation. Thus, DNMT3A functions as a molecular switch, repressing neural to favor neural crest cell fate. PMID:23124063

  1. A Unique Missense Allele of BAF155, a Core BAF Chromatin Remodeling Complex Protein, Causes Neural Tube Closure Defects in Mice

    PubMed Central

    Harmacek, Laura; Watkins-Chow, Dawn E.; Chen, Jianfu; Jones, Kenneth L.; Pavan, William J.; Salbaum, J. Michael; Niswander, Lee

    2015-01-01

    Failure of embryonic neural tube closure results in the second most common class of birth defects known as neural tube defects (NTDs). While NTDs are likely the result of complex multigenic dysfunction, it is not known whether polymorphisms in epigenetic regulators may be risk factors for NTDs. Here we characterized Baf155msp3, a unique ENU-induced allele in mice. Homozygous Baf155mps3 embryos exhibit highly penetrant exencephaly, allowing us to investigate the roles of an assembled, but malfunctional BAF chromatin remodeling complex in vivo at the time of neural tube closure. Evidence of defects in proliferation and apoptosis were found within the neural tube. RNA-Seq analysis revealed that surprisingly few genes showed altered expression in Baf155 mutant neural tissue, given the broad epigenetic role of the BAF complex, but included genes involved in neural development and cell survival. Moreover, gene expression changes between individual mutants were variable even though the NTD was consistently observed. This suggests that inconsistent gene regulation contributes to failed neural tube closure. These results shed light on the role of the BAF complex in the process of neural tube closure and highlight the importance of studying missense alleles to understand epigenetic regulation during critical phases of development. PMID:24170322

  2. Sulf1 influences the Shh morphogen gradient during the dorsal ventral patterning of the neural tube in Xenopus tropicalis.

    PubMed

    Ramsbottom, Simon A; Maguire, Richard J; Fellgett, Simon W; Pownall, Mary Elizabeth

    2014-07-15

    Genetic studies have established that heparan sulphate proteoglycans (HSPGs) are required for signalling by key developmental regulators, including Hedgehog, Wnt/Wg, FGF, and BMP/Dpp. Post-synthetic remodelling of heparan sulphate (HS) by Sulf1 has been shown to modulate these same signalling pathways. Sulf1 codes for an N-acetylglucosamine 6-O-endosulfatase, an enzyme that specifically removes the 6-O sulphate group from glucosamine in highly sulfated regions of HS chains. One striking aspect of Sulf1 expression in all vertebrates is its co-localisation with that of Sonic hedgehog in the floor plate of the neural tube. We show here that Sulf1 is required for normal specification of neural progenitors in the ventral neural tube, a process known to require a gradient of Shh activity. We use single-cell injection of mRNA coding for GFP-tagged Shh in early Xenopus embryos and find that Sulf1 restricts ligand diffusion. Moreover, we find that the endogenous distribution of Shh protein in Sulf1 knockdown embryos is altered, where a less steep ventral to dorsal gradient forms in the absence of Sulf1, resulting in more a diffuse distribution of Shh. These data point to an important role for Sulf1 in the ventral neural tube, and suggests a mechanism whereby Sulf1 activity shapes the Shh morphogen gradient by promoting ventral accumulation of high levels of Shh protein. PMID:24768893

  3. Fat1 interacts with Fat4 to regulate neural tube closure, neural progenitor proliferation and apical constriction during mouse brain development.

    PubMed

    Badouel, Caroline; Zander, Mark A; Liscio, Nicole; Bagherie-Lachidan, Mazdak; Sopko, Richelle; Coyaud, Etienne; Raught, Brian; Miller, Freda D; McNeill, Helen

    2015-08-15

    Mammalian brain development requires coordination between neural precursor proliferation, differentiation and cellular organization to create the intricate neuronal networks of the adult brain. Here, we examined the role of the atypical cadherins Fat1 and Fat4 in this process. We show that mutation of Fat1 in mouse embryos causes defects in cranial neural tube closure, accompanied by an increase in the proliferation of cortical precursors and altered apical junctions, with perturbations in apical constriction and actin accumulation. Similarly, knockdown of Fat1 in cortical precursors by in utero electroporation leads to overproliferation of radial glial precursors. Fat1 interacts genetically with the related cadherin Fat4 to regulate these processes. Proteomic analysis reveals that Fat1 and Fat4 bind different sets of actin-regulating and junctional proteins. In vitro data suggest that Fat1 and Fat4 form cis-heterodimers, providing a mechanism for bringing together their diverse interactors. We propose a model in which Fat1 and Fat4 binding coordinates distinct pathways at apical junctions to regulate neural progenitor proliferation, neural tube closure and apical constriction. PMID:26209645

  4. LRP6 exerts non-canonical effects on Wnt signaling during neural tube closure

    PubMed Central

    Gray, Jason D.; Kholmanskikh, Stanislav; Castaldo, Bozena S.; Hansler, Alex; Chung, Heekyung; Klotz, Brian; Singh, Shawn; Brown, Anthony M. C.; Ross, M. Elizabeth

    2013-01-01

    Low-density lipoprotein receptor related protein 6 (Lrp6) mutational effects on neurulation were examined using gain (Crooked tail, Lrp6Cd) and loss (Lrp6?) of function mouse lines. Two features often associated with canonical Wnt signaling, dorsal–ventral patterning and proliferation, were no different from wild-type (WT) in the Lrp6Cd/Cd neural tube. Lrp6?/? embryos showed reduced proliferation and subtle patterning changes in the neural folds. Cell polarity defects in both Lrp6Cd/Cd and Lrp6?/? cranial folds were indicated by cell shape, centrosome displacement and failure of F-actin and GTP-RhoA accumulation at the apical surface. Mouse embryonic fibroblasts (MEFs) derived from Lrp6Cd/Cd or Lrp6?/? embryos exhibited elevated and decreased RhoA basal activity levels, respectively. While ligand-independent activation of canonical Wnt signaling, bypassing Lrp-Frizzled receptors, did not activate RhoA, non-canonical Wnt5a stimulation of RhoA activity was impaired in Lrp6?/? MEFs. RhoA inhibition exacerbated NTDs in cultured Lrp6 knockout embryos compared with WT littermates. In contrast, a ROCK inhibitor rescued Lrp6Cd/Cd embryos from NTDs. Lrp6 co-immunoprecipitated with Disheveled-associated activator of morphogenesis 1 (DAAM1), a formin promoting GEF activity in Wnt signaling. Biochemical and cell biological data revealed intracellular accumulation of Lrp6Cd protein where interaction with DAAM1 could account for observed elevated RhoA activity. Conversely, null mutation that eliminates Lrp6 interaction with DAAM1 led to lower basal RhoA activity in Lrp6?/? embryos. These results indicate that Lrp6 mediates not only canonical Wnt signaling, but can also modulate non-canonical pathways involving RhoA-dependent mechanisms to impact neurulation, possibly through intracellular complexes with DAAM1. PMID:23773994

  5. [Prevalence of neural tube defects and estimation of cases averted in the post-fortification period in Argentina].

    PubMed

    Bidondo, María P; Liascovich, Rosa; Barbero, Pablo; Groisman, Boris

    2015-12-01

    Periconceptional intake of folic acid has demonstrated to be effective to reduce the frequency of neural tube defects, and food fortification has been one of the strategies implemented to increase it. An update is herein presented on the reduced prevalence of neural tube defect cases in the post-fortification period in Argentina and an estimation of cases averted in the 2005-2013 period as a result of this intervention. When comparing the prevalence observed in the post-fortification period to that reported in the pre-fortification period, anencephaly and encephalocele decreased by 66%, and spina bifida, by 47%, which were significant reductions. The estimated number of cases averted was higher for anencephaly, followed by spina bifida; encephalocele showed the lowest number of cases averted given that the prevalence of this defect was smaller. The decrease observed in the prevalence supports findings from previous studies on the impact of fortification. PMID:26593794

  6. The interaction between Shroom3 and Rho-kinase is required for neural tube morphogenesis in mice

    PubMed Central

    Das, Debamitra; Zalewski, Jenna K.; Mohan, Swarna; Plageman, Timothy F.; VanDemark, Andrew P.; Hildebrand, Jeffrey D.

    2014-01-01

    ABSTRACT Shroom3 is an actin-associated regulator of cell morphology that is required for neural tube closure, formation of the lens placode, and gut morphogenesis in mice and has been linked to chronic kidney disease and directional heart looping in humans. Numerous studies have shown that Shroom3 likely regulates these developmental processes by directly binding to Rho-kinase and facilitating the assembly of apically positioned contractile actomyosin networks. We have characterized the molecular basis for the neural tube defects caused by an ENU-induced mutation that results in an arginine-to-cysteine amino acid substitution at position 1838 of mouse Shroom3. We show that this substitution has no effect on Shroom3 expression or localization but ablates Rock binding and renders Shroom3 non-functional for the ability to regulate cell morphology. Our results indicate that Rock is the major downstream effector of Shroom3 in the process of neural tube morphogenesis. Based on sequence conservation and biochemical analysis, we predict that the Shroom-Rock interaction is highly conserved across animal evolution and represents a signaling module that is utilized in a variety of biological processes. PMID:25171888

  7. Neural tube opening and abnormal extraembryonic membrane development in SEC23A deficient mice

    PubMed Central

    Zhu, Min; Tao, Jiayi; Vasievich, Matthew P.; Wei, Wei; Zhu, Guojing; Khoriaty, Rami N.; Zhang, Bin

    2015-01-01

    COPII (coat protein complex-II) vesicles transport proteins from the endoplasmic reticulum (ER) to the Golgi. Higher eukaryotes have two or more paralogs of most COPII components. Here we characterize mice deficient for SEC23A and studied interactions of Sec23a null allele with the previously reported Sec23b null allele. SEC23A deficiency leads to mid-embryonic lethality associated with defective development of extraembryonic membranes and neural tube opening in midbrain. Secretion defects of multiple collagen types are observed in different connective tissues, suggesting that collagens are primarily transported in SEC23A-containing vesicles in these cells. Other extracellular matrix proteins, such as fibronectin, are not affected by SEC23A deficiency. Intracellular accumulation of unsecreted proteins leads to strong induction of the unfolded protein response in collagen-producing cells. No collagen secretion defects are observed in SEC23B deficient embryos. We report that E-cadherin is a cargo that accumulates in acini of SEC23B deficient pancreas and salivary glands. Compensatory increase of one paralog is observed in the absence of the second paralog. Haploinsufficiency of the remaining Sec23 paralog on top of homozygous inactivation of the first paralog leads to earlier lethality of embryos. Our results suggest that mammalian SEC23A and SEC23B transport overlapping yet distinct spectra of cargo in vivo. PMID:26494538

  8. Neural tube opening and abnormal extraembryonic membrane development in SEC23A deficient mice.

    PubMed

    Zhu, Min; Tao, Jiayi; Vasievich, Matthew P; Wei, Wei; Zhu, Guojing; Khoriaty, Rami N; Zhang, Bin

    2015-01-01

    COPII (coat protein complex-II) vesicles transport proteins from the endoplasmic reticulum (ER) to the Golgi. Higher eukaryotes have two or more paralogs of most COPII components. Here we characterize mice deficient for SEC23A and studied interactions of Sec23a null allele with the previously reported Sec23b null allele. SEC23A deficiency leads to mid-embryonic lethality associated with defective development of extraembryonic membranes and neural tube opening in midbrain. Secretion defects of multiple collagen types are observed in different connective tissues, suggesting that collagens are primarily transported in SEC23A-containing vesicles in these cells. Other extracellular matrix proteins, such as fibronectin, are not affected by SEC23A deficiency. Intracellular accumulation of unsecreted proteins leads to strong induction of the unfolded protein response in collagen-producing cells. No collagen secretion defects are observed in SEC23B deficient embryos. We report that E-cadherin is a cargo that accumulates in acini of SEC23B deficient pancreas and salivary glands. Compensatory increase of one paralog is observed in the absence of the second paralog. Haploinsufficiency of the remaining Sec23 paralog on top of homozygous inactivation of the first paralog leads to earlier lethality of embryos. Our results suggest that mammalian SEC23A and SEC23B transport overlapping yet distinct spectra of cargo in vivo. PMID:26494538

  9. Agenesis of the corpus callosum associated with spinal open neural tube defect

    PubMed Central

    Elgamal, Essam A.; Elwatidy, Sherif M.; Alhabib, Amro F.; Jamjoom, Zain B.; Murshid, Waleed R.; Hassan, Hamdy H.; Salih, Mustafa A.

    2014-01-01

    Objective: To ascertain the incidence and clinical implications of agenesis of the corpus callosum (ACC) in spinal open neural tube defects (SONTD). Methods: All cases of SONTD registered at the Spina Bifida Clinic in King Khalid University Hospital, Riyadh, Saudi Arabia between 1995 and 2010 were retrospectively reviewed, and mid-sagittal MRI of the corpus callosum (CC) area was analyzed in each case. Neurodevelopmental outcome was classified as poor in children with seizures, severe neurodevelopmental impairment, or death. Results: Thirty-eight patients (45.8%) with ACC were identified among 83 cases with SONTD. Patients’ age ranged between one and 16 years. Total ACC was found in 10 patients, partial ACC in 25, and in 3 patients, the CC was hypoplastic. Active hydrocephalus was an associated finding in 9 out of 10 patients with total ACC, 22 out of 25 with partial ACC, and in all patients with hypoplasia of the CC. Thirteen patients (34.2%) had normal intellectual function, whereas 24 patients presented with learning disability, epilepsy, or poor intellectual function; and one patient died of respiratory failure. Conclusion: Agenesis of the corpus callosum is found in a significant portion of patients with SONTD. When associated with hydrocephalus, its presence affects neuro-developmental outcome. PMID:25551114

  10. Use of local neural tube defect registers to interpret national trends.

    PubMed

    Hey, K; O'Donnell, M; Murphy, M; Jones, N; Botting, B

    1994-11-01

    To conduct a number of studies into the prevalence of neural tube defects (NTD) in the area covered by the Oxford Record Linkage Study (ORLS), multiple sources were used to build a local register of cases occurring in Oxfordshire and West Berkshire between 1968-1990. One source of potential cases--namely, termination and congenital malformation monitoring data available for the locality from the Office of Population Censuses and Surveys (OPCS) data--were kept separate. Comparison of the local cases recorded by OPCS and those known to the register from 1974-1990, using the method of capture-recapture, suggested that national data are only about two thirds complete, but that this underreporting is likely to be reasonably consistent from year to year. OPCS data can therefore be used to study NTD trends if not absolute risks. The local register seemed, by the same yardstick, to be very complete and is being used in a variety of studies of the occurrence of NTD. Survival to one year in this area, over the period 1968-1990, has only improved in the recent past, if at all. Most NTD pregnancies now end in termination rather than birth, and there has been a true decline in the occurrence of NTDs, and likewise the different subtypes. PMID:7820716

  11. Folic Acid Intake and Neural Tube Defects: Two Egyptian Centers Experience

    PubMed Central

    El-Shabrawi, Mortada H.; Kamal, Naglaa Mohamed; Elhusseini, Mona Abbas; Hussein, Laila; Abdallah, Enas Abdallah Ali; Ali, Yahia Zakaria Abdelalim; Azab, Ahmed Abelfattah; Salama, Mostafa Abdelazim; Kassab, Muna; Krawinkel, Michael

    2015-01-01

    Abstract Neural tube defects (NTDs) are a group of congenital malformations with worldwide distribution and complex etiopathogenesis. Folic acid plays a pivotal role in their prevention. We aimed to identify the protective effect of folic acid intake against NTDs and its dependence on different socioeconomic and environmental factors in a cohort of mothers in Egypt. A cross-sectional study was carried over a period of 12 months on mothers who gave birth to babies with NTDs (group 1) and a control group with healthy offsprings (group 2). Both groups completed 2 questionnaires: food frequency questionnaire targeting the daily folate intake, and socioeconomic status and medical history questionnaire. Both groups of mothers received folate <800??g/day, recommended for pregnant women. A strong association was detected between NTDs and urban residency with medium educated mothers, with negative consanguinity, who had folate intake < 400??g daily, and who had their food long cooked. Each of these factors separately had a limited impact to cause NTDs, but when present together they did augment each other. Interestingly enough is the role of fava bean, cauliflower, spinach, and mango in predisposing of NTDs in the presence of the above-mentioned factors. The protective effect of folic acid intake against NTDs may depend on the synergism of different socioeconomic and environmental factors (which differ from country to another). In Egypt, females especially the medium-educated who live in urban areas should be well-informed with the value of folate intake in the periconceptional period. PMID:26376380

  12. Achieving a public health recommendation for preventing neural tube defects with folic acid.

    PubMed Central

    Werler, M M; Louik, C; Mitchell, A A

    1999-01-01

    OBJECTIVES: This study examined 3 approaches to achieving the public health recommendation that all women of child-bearing age ingest 0.40 mg of folic acid per day to reduce the occurrence of neural tube defects (NTDs). METHODS: A total of 1136 mothers of infants with major malformations from the Boston and Philadelphia areas, whose pregnancies began from 1993 to 1995, were interviewed within 6 months of delivery about vitamin supplementation, dietary intakes, and other factors. RESULTS: Seventy-one percent of the 1136 women in the study did not take folic acid--containing supplements daily before conception, but the proportion decreased over the years of the study. Women not taking supplements consumed an average of 0.25 mg of naturally occurring folates daily. On the basis of dietary intakes reported by women not taking folic acid supplements, a simulation of cereal grain fortification with folic acid at the level required by the US Food and Drug Administration showed that an average of only 0.13 mg of folic acid would be ingested daily. CONCLUSIONS: With consumption of folic acid only through dietary intake, sizeable portions of the childbearing population would receive less than the level of folic acid recommended for preventing NTDs. Even with food fortification, women of childbearing age should be advised to take folic acid--containing supplements on a daily basis. PMID:10553381

  13. Glycine decarboxylase deficiency causes neural tube defects and features of non-ketotic hyperglycinemia in mice

    PubMed Central

    Pai, Yun Jin; Leung, Kit-Yi; Savery, Dawn; Hutchin, Tim; Prunty, Helen; Heales, Simon; Brosnan, Margaret E.; Brosnan, John T.; Copp, Andrew J.; Greene, Nicholas D.E.

    2015-01-01

    Glycine decarboxylase (GLDC) acts in the glycine cleavage system to decarboxylate glycine and transfer a one-carbon unit into folate one-carbon metabolism. GLDC mutations cause a rare recessive disease non-ketotic hyperglycinemia (NKH). Mutations have also been identified in patients with neural tube defects (NTDs); however, the relationship between NKH and NTDs is unclear. We show that reduced expression of Gldc in mice suppresses glycine cleavage system activity and causes two distinct disease phenotypes. Mutant embryos develop partially penetrant NTDs while surviving mice exhibit post-natal features of NKH including glycine accumulation, early lethality and hydrocephalus. In addition to elevated glycine, Gldc disruption also results in abnormal tissue folate profiles, with depletion of one-carbon-carrying folates, as well as growth retardation and reduced cellular proliferation. Formate treatment normalizes the folate profile, restores embryonic growth and prevents NTDs, suggesting that Gldc deficiency causes NTDs through limiting supply of one-carbon units from mitochondrial folate metabolism. PMID:25736695

  14. Role of arsenic as a reproductive toxin with particular attention to neural tube defects

    SciTech Connect

    Shalat, S.L.; Walker, D.B.; Finnell, R.H.

    1996-10-01

    Arsenic has been recognized as a human toxicant for over 2000 years. More recently it has been readily accepted as a human carcinogen. Animal research has demonstrated arsenic`s ability to have profound detrimental effects on the developing embryo in avian and mamalian species. This article comprehensively reviews the human and animal literature on the subject of the reproductive toxicity of arsenic. A variety of endpoints are considered, including spontaneous abortion, cardiovascular defects, and arsenic`s role in the causation of neural tube defects (NTDs). A summary of the literature that has examined the various postulated mechanisms by which arsenic may produce NTDs is also considered. In addition, a discussion of literature relative to the presence of arsenic in the general environment and in the workplace presented. This article reaches the conclusion that while further research is clearly needed, particularly on the potential toxicity of organic arsenical compounds, the current literature suggests it may be prudent and appropriate to treat inorganic arsenic as a probable human reproductive toxin. 132 refs.

  15. Folic Acid Intake and Neural Tube Defects: Two Egyptian Centers Experience.

    PubMed

    El-Shabrawi, Mortada H; Kamal, Naglaa Mohamed; Elhusseini, Mona Abbas; Hussein, Laila; Abdallah, Enas Abdallah Ali; Ali, Yahia Zakaria Abdelalim; Azab, Ahmed Abelfattah; Salama, Mostafa Abdelazim; Kassab, Muna; Krawinkel, Michael

    2015-09-01

    Neural tube defects (NTDs) are a group of congenital malformations with worldwide distribution and complex etiopathogenesis. Folic acid plays a pivotal role in their prevention. We aimed to identify the protective effect of folic acid intake against NTDs and its dependence on different socioeconomic and environmental factors in a cohort of mothers in Egypt. A cross-sectional study was carried over a period of 12 months on mothers who gave birth to babies with NTDs (group 1) and a control group with healthy offsprings (group 2). Both groups completed 2 questionnaires: food frequency questionnaire targeting the daily folate intake, and socioeconomic status and medical history questionnaire. Both groups of mothers received folate <800??g/day, recommended for pregnant women. A strong association was detected between NTDs and urban residency with medium educated mothers, with negative consanguinity, who had folate intake < 400??g daily, and who had their food long cooked. Each of these factors separately had a limited impact to cause NTDs, but when present together they did augment each other. Interestingly enough is the role of fava bean, cauliflower, spinach, and mango in predisposing of NTDs in the presence of the above-mentioned factors. The protective effect of folic acid intake against NTDs may depend on the synergism of different socioeconomic and environmental factors (which differ from country to another). In Egypt, females especially the medium-educated who live in urban areas should be well-informed with the value of folate intake in the periconceptional period. PMID:26376380

  16. Prevention of valproic acid-induced neural tube defects by sildenafil citrate.

    PubMed

    Tiboni, Gian Mario; Ponzano, Adalisa

    2015-08-15

    This study was undertaken to test the effects of sildenafil citrate (SC), a type 5 phosphodiesterase inhibitor, on valproic acid (VPA)-induced teratogenesis. On gestation day (GD) 8, ICR (CD-1) mice were treated by gastric intubation with SC at 0 (vehicle), 1.0, 2.5, 5.0 or 10mg/kg. One hour later, animals received a teratogenic dose of VPA (600mg/kg) or vehicle. Developmental endpoints were evaluated near the end of gestation. Twenty-eighth percent of fetuses exposed to VPA had neural tube defects (exencephaly). Pretreatment with SC at 2.5, 5.0 or 10mg/kg significantly reduced the rate of VPA-induced exencephaly to 15.9%, 13.7%, and 10.0%, respectively. Axial skeletal defects were observed in 75.8% of VPA-exposed fetuses. Pre-treatment with SC at 10mg/kg, but not at lower doses, significantly decreased the rate of skeletally affected fetuses to 61.6%. These results show that SC, which prolongs nitric oxide (NO) signaling action protects from VPA-induced teratogenesis. PMID:25797655

  17. Sequential contraction and exchange of apical junctions drives zippering and neural tube closure in a simple chordate.

    PubMed

    Hashimoto, Hidehiko; Robin, Francois B; Sherrard, Kristin M; Munro, Edwin M

    2015-01-26

    Unidirectional zippering is a key step in neural tube closure that remains poorly understood. Here, we combine experimental and computational approaches to identify the mechanism for zippering in a basal chordate, Ciona intestinalis. We show that myosin II is activated sequentially from posterior to anterior along the neural/epidermal (Ne/Epi) boundary just ahead of the advancing zipper. This promotes rapid shortening of Ne/Epi junctions, driving the zipper forward and drawing the neural folds together. Cell contact rearrangements (Ne/Epi + Ne/Epi ? Ne/Ne + Epi/Epi) just behind the zipper lower tissue resistance to zipper progression by allowing transiently stretched cells to detach and relax toward isodiametric shapes. Computer simulations show that measured differences in junction tension, timing of primary contractions, and delay before cell detachment are sufficient to explain the speed and direction of zipper progression and highlight key advantages of a sequential contraction mechanism for robust efficient zippering. PMID:25625209

  18. Maternal choline concentrations during pregnancy and choline-related genetic variants as risk factors for neural tube defects123

    PubMed Central

    Mills, James L; Fan, Ruzong; Brody, Lawrence C; Liu, Aiyi; Ueland, Per M; Wang, Yifan; Kirke, Peadar N; Shane, Barry; Molloy, Anne M

    2014-01-01

    Background: Low maternal choline intake and blood concentration may be risk factors for having a child with a neural tube defect (NTD); however, the data are inconsistent. This is an important question to resolve because choline, if taken periconceptionally, might add to the protective effect currently being achieved by folic acid. Objective: We examined the relation between NTDs, choline status, and genetic polymorphisms reported to influence de novo choline synthesis to investigate claims that taking choline periconceptionally could reduce NTD rates. Design: Two study groups of pregnant women were investigated: women who had a current NTD-affected pregnancy (AP; n = 71) and unaffected controls (n = 214) and women who had an NTD in another pregnancy but not in the current pregnancy [nonaffected pregnancy (NAP); n = 98] and unaffected controls (n = 386). Blood samples to measure betaine and total choline concentrations and single nucleotide polymorphisms related to choline metabolism were collected at their first prenatal visit. Results: Mean (±SD) plasma total choline concentrations in the AP (2.8 ± 1.0 mmol/L) and control (2.9 ± 0.9 mmol/L) groups did not differ significantly. Betaine concentrations were not significantly different between the 2 groups. Total choline and betaine in the NAP group did not differ from controls. Cases were significantly more likely to have the G allele of phosphatidylethanolamine-N-methyltransferase (PEMT; V175M, +5465 G>A) rs7946 (P = 0.02). Conclusions: Our results indicate that maternal betaine and choline concentrations are not strongly associated with NTD risk. The association between PEMT rs7946 and NTDs requires confirmation. The addition of choline to folic acid supplements may not further reduce NTD risk. PMID:25240073

  19. A Neural Mechanism for Background Information-Gated Learning Based on Axonal-Dendritic Overlaps

    PubMed Central

    Mainetti, Matteo; Ascoli, Giorgio A.

    2015-01-01

    Experiencing certain events triggers the acquisition of new memories. Although necessary, however, actual experience is not sufficient for memory formation. One-trial learning is also gated by knowledge of appropriate background information to make sense of the experienced occurrence. Strong neurobiological evidence suggests that long-term memory storage involves formation of new synapses. On the short time scale, this form of structural plasticity requires that the axon of the pre-synaptic neuron be physically proximal to the dendrite of the post-synaptic neuron. We surmise that such “axonal-dendritic overlap” (ADO) constitutes the neural correlate of background information-gated (BIG) learning. The hypothesis is based on a fundamental neuroanatomical constraint: an axon must pass close to the dendrites that are near other neurons it contacts. The topographic organization of the mammalian cortex ensures that nearby neurons encode related information. Using neural network simulations, we demonstrate that ADO is a suitable mechanism for BIG learning. We model knowledge as associations between terms, concepts or indivisible units of thought via directed graphs. The simplest instantiation encodes each concept by single neurons. Results are then generalized to cell assemblies. The proposed mechanism results in learning real associations better than spurious co-occurrences, providing definitive cognitive advantages. PMID:25767887

  20. Association of selected persistent organic pollutants in the placenta with the risk of neural tube defects.

    PubMed

    Ren, Aiguo; Qiu, Xinghua; Jin, Lei; Ma, Jin; Li, Zhiwen; Zhang, Le; Zhu, Huiping; Finnell, Richard H; Zhu, Tong

    2011-08-01

    Persistent organic pollutants (POPs) have been associated with a wide range of adverse health effects. Our case-control study was performed to explore the association between placental levels of selected POPs and risks for neural tube defects (NTDs) in a Chinese population with a high prevalence of NTDs. Cases included 80 fetuses or newborns with NTDs, whereas the controls were 50 healthy, nonmalformed newborn infants. Placental concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, polychlorinated biphenyls, and polybrominated diphenyl ethers were analyzed by gas chromatography-mass spectrometry. The medians of PAHs, o,p'-isomers of dichlorodiphenyltrichloroethane (DDT) and metabolites, ?- and ?-hexachlorocyclohexane (HCH), and ?-endosulfan were significantly higher in case placentas than in controls. PAH concentrations above the median were associated with a 4.52-fold [95% confidence interval (CI), 2.10-9.74) increased risk for any NTDs, and 5.84- (95% CI, 2.28-14.96) and 3.71-fold (95% CI, 1.57-8.79) increased risks for anencephaly and spina bifida, respectively. A dose-response relationship was observed between PAH levels and the risk of NTDs, with odds ratios for the second, third, and fourth quartiles, compared with the first, of 1.77- (95% CI, 0.66-4.76), 3.83- (95% CI, 1.37-10.75), and 11.67-fold (95% CI, 3.28-41.49), respectively. A dose-response relationship was observed for anencephaly and spina bifida subtypes. Similar results were observed for o,p'-DDT and metabolites, ?-HCH, ?-HCH, and ?-endosulfan, whereas no dose-response relationship was observed for the last two pollutants. Elevated placental concentrations of PAHs, o,p'-DDT and metabolites, and ?-HCH were associated with increased risks of NTDs in this population. PMID:21768370

  1. Punicalagin exerts protective effect against high glucose-induced cellular stress and neural tube defects.

    PubMed

    Zhong, Jianxiang; Reece, E Albert; Yang, Peixin

    2015-11-13

    Maternal diabetes-induced birth defects remain a significant health problem. Studying the effect of natural compounds with antioxidant properties and minimal toxicities on diabetic embryopathy may lead to the development of new and safe dietary supplements. Punicalagin is a primary polyphenol found in pomegranate juice, which possesses antioxidant, anti-inflammatory and anti-tumorigenic properties, suggesting a protective effect of punicalagin on diabetic embryopathy. Here, we examined whether punicalagin could reduce high glucose-induced neural tube defects (NTDs), and if this rescue occurs through blockage of cellular stress and caspase activation. Embryonic day 8.5 (E8.5) mouse embryos were cultured for 24 or 36 h with normal (5 mM) glucose or high glucose (16.7 mM), in presence or absence of 10 or 20 ?M punicalagin. 10 ?M punicalagin slightly reduced NTD formation under high glucose conditions; however, 20 ?M punicalagin significantly inhibited high glucose-induced NTD formation. Punicalagin suppressed high glucose-induced lipid peroxidation marker 4-hydroxynonenal, nitrotyrosine-modified proteins, and lipid peroxides. Moreover, punicalagin abrogated endoplasmic reticulum stress by inhibiting phosphorylated protein kinase ribonucleic acid (RNA)-like ER kinase (p-PERK), phosphorylated inositol-requiring protein-1? (p-IRE1?), phosphorylated eukaryotic initiation factor 2? (p-eIF2?), C/EBP-homologous protein (CHOP), binding immunoglobulin protein (BiP) and x-box binding protein 1 (XBP1) mRNA splicing. Additionally, punicalagin suppressed high glucose-induced caspase 3 and caspase 8 cleavage. Punicalagin reduces high glucose-induced NTD formation by blocking cellular stress and caspase activation. These observations suggest punicalagin supplements could mitigate the teratogenic effects of hyperglycemia in the developing embryo, and possibly prevent diabetes-induced NTDs. PMID:26453010

  2. Maternal exposure to arsenic, cadmium, lead, and mercury and neural tube defects in offspring

    SciTech Connect

    Brender, Jean D. . E-mail: jdbrender@aol.com; Suarez, Lucina; Felkner, Marilyn; Gilani, Zunera; Stinchcomb, David; Moody, Karen; Henry, Judy; Hendricks, Katherine

    2006-05-15

    Arsenic, cadmium, lead, and mercury are neurotoxins, and some studies suggest that these elements might also be teratogens. Using a case-control study design, we investigated the relation between exposure to these heavy metals and neural tube defects (NTDs) in offspring of Mexican-American women living in 1 of the 14 Texas counties bordering Mexico. A total of 184 case-women with NTD-affected pregnancies and 225 control-women with normal live births were interviewed about their environmental and occupational exposures during the periconceptional period. Biologic samples for blood lead and urinary arsenic, cadmium, and mercury were also obtained for a subset of these women. Overall, the median levels of these biomarkers for heavy metal exposure did not differ significantly (P>0.05) between case- and control-women. However, among women in the highest income group, case-women were nine times more likely (95% confidence interval (CI) 1.4-57) than control-women to have a urinary mercury >=5.62{mu}g/L. Case-women were 4.2 times more likely (95% CI 1.1-16) to report burning treated wood during the periconceptional period than control-women. Elevated odds ratios (ORs) were observed for maternal and paternal occupational exposures to arsenic and mercury, but the 95% CIs were consistent with unity. The 95% CIs of the ORs were also consistent with unity for higher levels of arsenic, cadmium, lead, and mercury in drinking water and among women who lived within 2 miles at the time of conception to industrial facilities with reported emissions of any of these heavy metals. Our findings suggest that maternal exposures to arsenic, cadmium, or lead are probably not significant risk factors for NTDs in offspring. However, the elevated urinary mercury levels found in this population and exposures to the combustion of treated wood may warrant further investigation.

  3. Eddy Current Signature Classification of Steam Generator Tube Defects Using A Learning Vector Quantization Neural Network

    SciTech Connect

    Gabe V. Garcia

    2005-01-03

    A major cause of failure in nuclear steam generators is degradation of their tubes. Although seven primary defect categories exist, one of the principal causes of tube failure is intergranular attack/stress corrosion cracking (IGA/SCC). This type of defect usually begins on the secondary side surface of the tubes and propagates both inwards and laterally. In many cases this defect is found at or near the tube support plates.

  4. Epigenetic Profiles in Children with a Neural Tube Defect; A Case-Control Study in Two Populations

    PubMed Central

    Stolk, Lisette; Bouwland-Both, Marieke I.; van Mill, Nina H.; Verbiest, Michael M. P. J.; Eilers, Paul H. C.; Zhu, Huiping; Suarez, Lucina; Uitterlinden, André G.; Steegers-Theunissen, Régine P. M.

    2013-01-01

    Folate deficiency is implicated in the causation of neural tube defects (NTDs). The preventive effect of periconceptional folic acid supplement use is partially explained by the treatment of a deranged folate-dependent one carbon metabolism, which provides methyl groups for DNA-methylation as an epigenetic mechanism. Here, we hypothesize that variations in DNA-methylation of genes implicated in the development of NTDs and embryonic growth are part of the underlying mechanism. In 48 children with a neural tube defect and 62 controls from a Dutch case-control study and 34 children with a neural tube defect and 78 controls from a Texan case-control study, we measured the DNA-methylation levels of imprinted candidate genes (IGF2-DMR, H19, KCNQ1OT1) and non-imprinted genes (the LEKR/CCNL gene region associated with birth weight, and MTHFR and VANGL1 associated with NTD). We used the MassARRAY EpiTYPER assay from Sequenom for the assessment of DNA-methylation. Linear mixed model analysis was used to estimate associations between DNA-methylation levels of the genes and a neural tube defect. In the Dutch study group, but not in the Texan study group we found a significant association between the risk of having an NTD and DNA methylation levels of MTHFR (absolute decrease in methylation of ?0.33% in cases, P-value?=?0.001), and LEKR/CCNL (absolute increase in methylation: 1.36% in cases, P-value?=?0.048), and a borderline significant association for VANGL (absolute increase in methylation: 0.17% in cases, P-value?=?0.063). Only the association between MTHFR and NTD-risk remained significant after multiple testing correction. The associations in the Dutch study were not replicated in the Texan study. We conclude that the associations between NTDs and the methylation of the MTHFR gene, and maybe VANGL and LEKKR/CNNL, are in line with previous studies showing polymorphisms in the same genes in association with NTDs and embryonic development, respectively. PMID:24223810

  5. Analysis of MTR and MTRR Polymorphisms for Neural Tube Defects Risk Association

    PubMed Central

    Wang, Yongxin; Liu, Yuan; Ji, Wenyu; Qin, Hu; Wu, Hao; Xu, Danshu; Tukebai, Turtuohut; Wang, Zengliang

    2015-01-01

    Abstract Neural tube defects (NTDs) are the most common congenital defects of the central nervous system among neonates and the folate status during pregnancy was considered as the most important etiopathogenesis of NTDs. Besides, methionine synthase (MTR) gene and methionine synthase reductase (MTRR) gene were folate metabolism involved genes and had been investigated in several previous studies with inconsistent results. Hence, we aimed to explore the association of 4 selected single-nucleotide polymorphisms (SNPs) on MTRR/MTR gene and the susceptibility of NTDs in a Chinese population. Seven SNPs were selected from HapMap databases with Haploview 4.2 software. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to genotype the polymorphisms from blood samples of 165 NTDs patients and 280 healthy controls. The correlation between these SNPs and NTDs risk was tested by Student t test and Chi-square test by STATA 11.0 software. Furthermore, we performed a meta-analysis of relevant studies to investigate the association between the SNPs MTRR 66A>G and MTR 2756A>G and the susceptibility of NTDs. An increased risk of NTDs was verified to be significantly associated with MTRR 66A>G (G allele vs. A allele: OR?=?1.36 (1.03–1.80), P?=?0.028; GG?+?AG vs. AA: OR?=?1.60 (1.05–2.43), P?=?0.027) and MTR 2756A>G (G allele vs. A allele: OR?=?1.45 (1.06–1.98), P?=?0.021; GG?+?AG vs. AA: OR?=?1.51 (1.02–2.23), P?=?0.038) in our study. However, the other SNPs in our analysis showed no significant association with NTDs risk (all P?>?0.05). Furthermore, the result of the meta-analysis supported the association between MTRR 66A>G and NTDs risk (G allele vs. A allele: OR?=?1.32, 95% CI?=?1.09–1.61, GG?+?GA vs. AA: OR?=?1.49, 95% CI?=?1.06–2.09, GG vs. AA: OR?=?1.61, 95% CI?=?1.04–2.49). Our study confirmed that the MTRR 66A>G and MTR 2756A>G were significantly associated with the increased NTDs risk in a Chinese population. The further meta-analysis enhance that MTRR 66A>G was connected with the susceptibility of NTDs widely. Further investigations based on more detailed stratification were recommended. PMID:26334892

  6. Long term trends in prevalence of neural tube defects in Europe: population based study

    PubMed Central

    Loane, Maria; de Walle, Hermien; Arriola, Larraitz; Addor, Marie-Claude; Barisic, Ingeborg; Beres, Judit; Bianchi, Fabrizio; Dias, Carlos; Draper, Elizabeth; Garne, Ester; Gatt, Miriam; Haeusler, Martin; Klungsoyr, Kari; Latos-Bielenska, Anna; Lynch, Catherine; McDonnell, Bob; Nelen, Vera; Neville, Amanda J; O’Mahony, Mary T; Queisser-Luft, Annette; Rankin, Judith; Rissmann, Anke; Ritvanen, Annukka; Rounding, Catherine; Sipek, Antonin; Tucker, David; Verellen-Dumoulin, Christine; Wellesley, Diana; Dolk, Helen

    2015-01-01

    Study question What are the long term trends in the total (live births, fetal deaths, and terminations of pregnancy for fetal anomaly) and live birth prevalence of neural tube defects (NTD) in Europe, where many countries have issued recommendations for folic acid supplementation but a policy for mandatory folic acid fortification of food does not exist? Methods This was a population based, observational study using data on 11?353 cases of NTD not associated with chromosomal anomalies, including 4162 cases of anencephaly and 5776 cases of spina bifida from 28 EUROCAT (European Surveillance of Congenital Anomalies) registries covering approximately 12.5 million births in 19 countries between 1991 and 2011. The main outcome measures were total and live birth prevalence of NTD, as well as anencephaly and spina bifida, with time trends analysed using random effects Poisson regression models to account for heterogeneities across registries and splines to model non-linear time trends. Summary answer and limitations Overall, the pooled total prevalence of NTD during the study period was 9.1 per 10?000 births. Prevalence of NTD fluctuated slightly but without an obvious downward trend, with the final estimate of the pooled total prevalence of NTD in 2011 similar to that in 1991. Estimates from Poisson models that took registry heterogeneities into account showed an annual increase of 4% (prevalence ratio 1.04, 95% confidence interval 1.01 to 1.07) in 1995-99 and a decrease of 3% per year in 1999-2003 (0.97, 0.95 to 0.99), with stable rates thereafter. The trend patterns for anencephaly and spina bifida were similar, but neither anomaly decreased substantially over time. The live birth prevalence of NTD generally decreased, especially for anencephaly. Registration problems or other data artefacts cannot be excluded as a partial explanation of the observed trends (or lack thereof) in the prevalence of NTD. What this study adds In the absence of mandatory fortification, the prevalence of NTD has not decreased in Europe despite longstanding recommendations aimed at promoting peri-conceptional folic acid supplementation and existence of voluntary folic acid fortification. Funding, competing interests, data sharing The study was funded by the European Public Health Commission, EUROCAT Joint Action 2011-2013. HD and ML received support from the European Commission DG Sanco during the conduct of this study. No additional data available. PMID:26601850

  7. Dual labeling of neural crest cells and blood vessels within chicken embryos using Chick(GFP) neural tube grafting and carbocyanine dye DiI injection.

    PubMed

    Delalande, Jean-Marie; Thapar, Nikhil; Burns, Alan J

    2015-01-01

    All developing organs need to be connected to both the nervous system (for sensory and motor control) as well as the vascular system (for gas exchange, fluid and nutrient supply). Consequently both the nervous and vascular systems develop alongside each other and share striking similarities in their branching architecture. Here we report embryonic manipulations that allow us to study the simultaneous development of neural crest-derived nervous tissue (in this case the enteric nervous system), and the vascular system. This is achieved by generating chicken chimeras via transplantation of discrete segments of the neural tube, and associated neural crest, combined with vascular DiI injection in the same embryo. Our method uses transgenic chick(GFP) embryos for intraspecies grafting, making the transplant technique more powerful than the classical quail-chick interspecies grafting protocol used with great effect since the 1970s. Chick(GFP)-chick intraspecies grafting facilitates imaging of transplanted cells and their projections in intact tissues, and eliminates any potential bias in cell development linked to species differences. This method takes full advantage of the ease of access of the avian embryo (compared with other vertebrate embryos) to study the co-development of the enteric nervous system and the vascular system. PMID:26065540

  8. Dual Labeling of Neural Crest Cells and Blood Vessels Within Chicken Embryos Using ChickGFP Neural Tube Grafting and Carbocyanine Dye DiI Injection

    PubMed Central

    Delalande, Jean-Marie; Thapar, Nikhil; Burns, Alan J.

    2015-01-01

    All developing organs need to be connected to both the nervous system (for sensory and motor control) as well as the vascular system (for gas exchange, fluid and nutrient supply). Consequently both the nervous and vascular systems develop alongside each other and share striking similarities in their branching architecture. Here we report embryonic manipulations that allow us to study the simultaneous development of neural crest-derived nervous tissue (in this case the enteric nervous system), and the vascular system. This is achieved by generating chicken chimeras via transplantation of discrete segments of the neural tube, and associated neural crest, combined with vascular DiI injection in the same embryo. Our method uses transgenic chickGFP embryos for intraspecies grafting, making the transplant technique more powerful than the classical quail-chick interspecies grafting protocol used with great effect since the 1970s. ChickGFP-chick intraspecies grafting facilitates imaging of transplanted cells and their projections in intact tissues, and eliminates any potential bias in cell development linked to species differences. This method takes full advantage of the ease of access of the avian embryo (compared with other vertebrate embryos) to study the co-development of the enteric nervous system and the vascular system. PMID:26065540

  9. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters

    PubMed Central

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915measuredsamples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rateand heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08. PMID:26624613

  10. Artificial Neural Networks-Based Software for Measuring Heat Collection Rate and Heat Loss Coefficient of Water-in-Glass Evacuated Tube Solar Water Heaters.

    PubMed

    Liu, Zhijian; Liu, Kejun; Li, Hao; Zhang, Xinyu; Jin, Guangya; Cheng, Kewei

    2015-01-01

    Measurements of heat collection rate and heat loss coefficient are crucial for the evaluation of in service water-in-glass evacuated tube solar water heaters. However, conventional measurement requires expensive detection devices and undergoes a series of complicated procedures. To simplify the measurement and reduce the cost, software based on artificial neural networks for measuring heat collection rate and heat loss coefficient of water-in-glass evacuated tube solar water heaters was developed. Using multilayer feed-forward neural networks with back-propagation algorithm, we developed and tested our program on the basis of 915measuredsamples of water-in-glass evacuated tube solar water heaters. This artificial neural networks-based software program automatically obtained accurate heat collection rateand heat loss coefficient using simply "portable test instruments" acquired parameters, including tube length, number of tubes, tube center distance, heat water mass in tank, collector area, angle between tubes and ground and final temperature. Our results show that this software (on both personal computer and Android platforms) is efficient and convenient to predict the heat collection rate and heat loss coefficient due to it slow root mean square errors in prediction. The software now can be downloaded from http://t.cn/RLPKF08. PMID:26624613

  11. Updated estimates of neural tube defects prevented by mandatory folic Acid fortification - United States, 1995-2011.

    PubMed

    Williams, Jennifer; Mai, Cara T; Mulinare, Joe; Isenburg, Jennifer; Flood, Timothy J; Ethen, Mary; Frohnert, Barbara; Kirby, Russell S

    2015-01-16

    In 1992, the U.S. Public Health Service recommended that all women capable of becoming pregnant consume 400 µg of folic acid daily to prevent neural tube defects (NTDs). NTDs are major birth defects of the brain and spine that occur early in pregnancy as a result of improper closure of the embryonic neural tube, which can lead to death or varying degrees of disability. The two most common NTDs are anencephaly and spina bifida. Beginning in 1998, the United States mandated fortification of enriched cereal grain products with 140 µg of folic acid per 100 g. Immediately after mandatory fortification, the birth prevalence of NTD cases declined. Fortification was estimated to avert approximately 1,000 NTD-affected pregnancies annually. To provide updated estimates of the birth prevalence of NTDs in the period after introduction of mandatory folic acid fortification (i.e., the post-fortification period), data from 19 population-based birth defects surveillance programs in the United States, covering the years 1999-2011, were examined. After the initial decrease, NTD birth prevalence during the post-fortification period has remained relatively stable. The number of births occurring annually without NTDs that would otherwise have been affected is approximately 1,326 (95% confidence interval = 1,122-1,531). Mandatory folic acid fortification remains an effective public health intervention. There remain opportunities for prevention among women with lower folic acid intakes, especially among Hispanic women, to further reduce the prevalence of NTDs in the United States. PMID:25590678

  12. Sept6 Is Required for Ciliogenesis in Kupffer's Vesicle, the Pronephros, and the Neural Tube during Early Embryonic Development

    PubMed Central

    Zhai, Gang; Gu, Qilin; He, Jiangyan; Lou, Qiyong; Chen, Xiaowen; Jin, Xia

    2014-01-01

    Septins are conserved filament-forming GTP-binding proteins that act as cellular scaffolds or diffusion barriers in a number of cellular processes. However, the role of septins in vertebrate development remains relatively obscure. Here, we show that zebrafish septin 6 (sept6) is first expressed in the notochord and then in nearly all of the ciliary organs, including Kupffer's vesicle (KV), the pronephros, eye, olfactory bulb, and neural tube. Knockdown of sept6 in zebrafish embryos results in reduced numbers and length of cilia in KV. Consequently, cilium-related functions, such as the left-right patterning of internal organs and nodal/spaw signaling, are compromised. Knockdown of sept6 also results in aberrant cilium formation in the pronephros and neural tube, leading to cilium-related defects in pronephros development and Sonic hedgehog (Shh) signaling. We further demonstrate that SEPT6 associates with acetylated ?-tubulin in vivo and localizes along the axoneme in the cilia of zebrafish pronephric duct cells as well as cultured ZF4 cells. Our study reveals a novel role of sept6 in ciliogenesis during early embryonic development in zebrafish. PMID:24469395

  13. Rho-kinase-dependent actin turnover and actomyosin disassembly are necessary for mouse spinal neural tube closure.

    PubMed

    Escuin, Sarah; Vernay, Bertrand; Savery, Dawn; Gurniak, Christine B; Witke, Walter; Greene, Nicholas D E; Copp, Andrew J

    2015-07-15

    The cytoskeleton is widely considered essential for neurulation, yet the mouse spinal neural tube can close despite genetic and non-genetic disruption of the cytoskeleton. To investigate this apparent contradiction, we applied cytoskeletal inhibitors to mouse embryos in culture. Preventing actomyosin cross-linking, F-actin assembly or myosin II contractile activity did not disrupt spinal closure. In contrast, inhibiting Rho kinase (ROCK, for which there are two isoforms ROCK1 and ROCK2) or blocking F-actin disassembly prevented closure, with apical F-actin accumulation and adherens junction disturbance in the neuroepithelium. Cofilin-1-null embryos yielded a similar phenotype, supporting the hypothesis that there is a key role for actin turnover. Co-exposure to Blebbistatin rescued the neurulation defects caused by RhoA inhibition, whereas an inhibitor of myosin light chain kinase, ML-7, had no such effect. We conclude that regulation of RhoA, Rho kinase, LIM kinase and cofilin signalling is necessary for spinal neural tube closure through precise control of neuroepithelial actin turnover and actomyosin disassembly. In contrast, actomyosin assembly and myosin ATPase activity are not limiting for closure. PMID:26040287

  14. Rho-kinase-dependent actin turnover and actomyosin disassembly are necessary for mouse spinal neural tube closure

    PubMed Central

    Escuin, Sarah; Vernay, Bertrand; Savery, Dawn; Gurniak, Christine B.; Witke, Walter; Greene, Nicholas D. E.; Copp, Andrew J.

    2015-01-01

    ABSTRACT The cytoskeleton is widely considered essential for neurulation, yet the mouse spinal neural tube can close despite genetic and non-genetic disruption of the cytoskeleton. To investigate this apparent contradiction, we applied cytoskeletal inhibitors to mouse embryos in culture. Preventing actomyosin cross-linking, F-actin assembly or myosin II contractile activity did not disrupt spinal closure. In contrast, inhibiting Rho kinase (ROCK, for which there are two isoforms ROCK1 and ROCK2) or blocking F-actin disassembly prevented closure, with apical F-actin accumulation and adherens junction disturbance in the neuroepithelium. Cofilin-1-null embryos yielded a similar phenotype, supporting the hypothesis that there is a key role for actin turnover. Co-exposure to Blebbistatin rescued the neurulation defects caused by RhoA inhibition, whereas an inhibitor of myosin light chain kinase, ML-7, had no such effect. We conclude that regulation of RhoA, Rho kinase, LIM kinase and cofilin signalling is necessary for spinal neural tube closure through precise control of neuroepithelial actin turnover and actomyosin disassembly. In contrast, actomyosin assembly and myosin ATPase activity are not limiting for closure. PMID:26040287

  15. Raltitrexed's effect on the development of neural tube defects in mice is associated with DNA damage, apoptosis, and proliferation.

    PubMed

    Dong, Yanting; Wang, Xiuwei; Zhang, Jianlin; Guan, Zhen; Xu, Lin; Wang, Jianhua; Zhang, Ting; Niu, Bo

    2015-01-01

    The causal metabolic pathway and the underlying mechanism between folate deficiency and neural tube defects (NTDs) remain obscure. Thymidylate (dTMP) is catalyzed by thymidylate synthase (TS) using the folate-derived one-carbon unit as the sole methyl donor. This study aims to examine the role of dTMP biosynthesis in the development of neural tube in mice by inhibition of TS via a specific inhibitor, raltitrexed (RTX). Pregnant mice were intraperitoneally injected with various doses of RTX on gestational day 7.5, and embryos were examined for the presence of NTDs on gestational day 11.5. TS activity and changes of dUMP and dTMP levels were measured following RTX treatment at the optimal dose. DNA damage was determined by detection of phosphorylated replication protein A2 (RPA2) and ?-H2AX in embryos with NTDs induced by RTX. Besides, apoptosis and proliferation were also analyzed in RTX-treated embryos with NTDs. We found that NTDs were highly occurred by the treatment of RTX at the optimal dose of 11.5 mg/kg b/w. RTX treatment significantly inhibited TS activity. Meanwhile, dTMP was decreased associated with the accumulation of dUMP in RTX-treated embryos. Phosphorylated RPA2 and ?-H2AX were significantly increased in RTX-treated embryos with NTDs compared to control. More apoptosis and decreased proliferation were also found in embryos with NTDs induced by RTX. These results indicate that impairment of dTMP biosynthesis caused by RTX led to the development of NTDs in mice. DNA damage and imbalance between apoptosis and proliferation may be potential mechanisms. PMID:25245820

  16. Folic acid and pantothenic acid protection against valproic acid-induced neural tube defects in CD-1 mice

    SciTech Connect

    Dawson, Jennifer E.; Raymond, Angela M.; Winn, Louise M. . E-mail: winnl@biology.queensu.ca

    2006-03-01

    In utero exposure to valproic acid (VPA) during pregnancy is associated with an increased risk of neural tube defects (NTDs). Although the mechanism by which VPA mediates these effects is unknown, VPA-initiated changes in embryonic protein levels have been implicated. The objectives of this study were to investigate the effect of in utero VPA exposure on embryonic protein levels of p53, NF-{kappa}B, Pim-1, c-Myb, Bax, and Bcl-2 in the CD-1 mouse. We also evaluated the protective effects of folic acid and pantothenic acid on VPA-induced NTDs and VPA-induced embryonic protein changes in this model. Pregnant CD-1 mice were administered a teratogenic dose of VPA prior to neural tube closure and embryonic protein levels were analyzed. In our study, VPA (400 mg/kg)-induced NTDs (24%) and VPA-exposed embryos with an NTD showed a 2-fold increase in p53, and 4-fold decreases in NF-{kappa}B, Pim-1, and c-Myb protein levels compared to their phenotypically normal littermates (P < 0.05). Additionally, VPA increased the ratio of embryonic Bax/Bcl-2 protein levels (P < 0.05). Pretreatment of pregnant dams with either folic acid or pantothenic acid prior to VPA significantly protected against VPA-induced NTDs (P < 0.05). Folic acid also reduced VPA-induced alterations in p53, NF-{kappa}B, Pim-1, c-Myb, and Bax/Bcl-2 protein levels, while pantothenic acid prevented VPA-induced alterations in NF-{kappa}B, Pim-1, and c-Myb. We hypothesize that folic acid and pantothenic acid protect CD-1 embryos from VPA-induced NTDs by independent, but not mutually exclusive mechanisms, both of which may be mediated by the prevention of VPA-induced alterations in proteins involved in neurulation.

  17. 3D Reconstitution of the Patterned Neural Tube from Embryonic Stem Cells

    PubMed Central

    Meinhardt, Andrea; Eberle, Dominic; Tazaki, Akira; Ranga, Adrian; Niesche, Marco; Wilsch-Bräuninger, Michaela; Stec, Agnieszka; Schackert, Gabriele; Lutolf, Matthias; Tanaka, Elly M.

    2014-01-01

    Summary Inducing organogenesis in 3D culture is an important aspect of stem cell research. Anterior neural structures have been produced from large embryonic stem cell (ESC) aggregates, but the steps involved in patterning such complex structures have been ill defined, as embryoid bodies typically contained many cell types. Here we show that single mouse ESCs directly embedded in Matrigel or defined synthetic matrices under neural induction conditions can clonally form neuroepithelial cysts containing a single lumen in 3D. Untreated cysts were uniformly dorsal and could be ventralized to floor plate (FP). Retinoic acid posteriorized cysts to cervical levels and induced localize FP formation yielding full patterning along the dorsal/ventral (DV) axis. Correct spatial organization of motor neurons, interneurons, and dorsal interneurons along the DV axis was observed. This system serves as a valuable tool for studying morphogen action in 3D and as a source of patterned spinal cord tissue. PMID:25454634

  18. 3D reconstitution of the patterned neural tube from embryonic stem cells.

    PubMed

    Meinhardt, Andrea; Eberle, Dominic; Tazaki, Akira; Ranga, Adrian; Niesche, Marco; Wilsch-Bräuninger, Michaela; Stec, Agnieszka; Schackert, Gabriele; Lutolf, Matthias; Tanaka, Elly M

    2014-12-01

    Inducing organogenesis in 3D culture is an important aspect of stem cell research. Anterior neural structures have been produced from large embryonic stem cell (ESC) aggregates, but the steps involved in patterning such complex structures have been ill defined, as embryoid bodies typically contained many cell types. Here we show that single mouse ESCs directly embedded in Matrigel or defined synthetic matrices under neural induction conditions can clonally form neuroepithelial cysts containing a single lumen in 3D. Untreated cysts were uniformly dorsal and could be ventralized to floor plate (FP). Retinoic acid posteriorized cysts to cervical levels and induced localize FP formation yielding full patterning along the dorsal/ventral (DV) axis. Correct spatial organization of motor neurons, interneurons, and dorsal interneurons along the DV axis was observed. This system serves as a valuable tool for studying morphogen action in 3D and as a source of patterned spinal cord tissue. PMID:25454634

  19. Self-organized criticality in a two-dimensional cellular automaton model of a magnetic flux tube with background flow

    NASA Astrophysics Data System (ADS)

    D?nil?, B.; Harko, T.; Mocanu, G.

    2015-11-01

    We investigate the transition to self-organized criticality in a two-dimensional model of a flux tube with a background flow. The magnetic induction equation, represented by a partial differential equation with a stochastic source term, is discretized and implemented on a two-dimensional cellular automaton. The energy released by the automaton during one relaxation event is the magnetic energy. As a result of the simulations, we obtain the time evolution of the energy release, of the system control parameter, of the event lifetime distribution and of the event size distribution, respectively, and we establish that a self-organized critical state is indeed reached by the system. Moreover, energetic initial impulses in the magnetohydrodynamic flow can lead to one-dimensional signatures in the magnetic two-dimensional system, once the self-organized critical regime is established. The applications of the model for the study of gamma-ray bursts (GRBs) is briefly considered, and it is shown that some astrophysical parameters of the bursts, like the light curves, the maximum released energy and the number of peaks in the light curve can be reproduced and explained, at least on a qualitative level, by working in a framework in which the systems settles in a self-organized critical state via magnetic reconnection processes in the magnetized GRB fireball.

  20. A Study on The Incidence of Neural Tube Defects in A Tertiary Care Hospital Over A Period of Five Years

    PubMed Central

    Subramanian, Manickam; Rajilarajendran, Hannahsugirthabai; Ramanujam, Sailatha; Saktivel, Sathiya; Sivaanandam, Renuka

    2015-01-01

    Introduction Several congenital malformations affect developing fetuses, among which Neural tube defect (NTD) is most common. Folic acid supplementation brought decline in the incidence of NTDs. The present study aims at finding the incidence of NTDs in a tertiary care hospital and compares the results with the similar Indian studies published earlier. Materials and Methods The study was done at Chettinad Hospital & Research Institute (CHRI), Kelambakkam. The total number of deliveries was recorded for a period of five years from 2009 to 2013. Fetuses which were still born with neural defect were collected and observed in detail externally for the sex, type of NTD and other associated anomalies. Indian studies published between 1987 and 2014 reporting the incidence of NTDs among the births occurred were retrieved from the Internet and their various observations were used for comparison. Results The number of deliveries conducted between 2009 and 2013 at CHRI was 3220. Of these, babies born with NTDs were nine (5 males and 4 females). The incidence of fetuses with meroanencephaly, holoanencephaly, craniorachischisis, encephalocele and myelocele were 0.62, 0.62, 0.93, 0.31 and 0.31 per 1000 births respectively. Overall incidence of NTDs in the present study was 2.79/1000 births. Fetuses with NTDs also had the following anomalies – Club foot, cleft lip and palate and exomphalos. Conclusion Comparing the results with the previous studies it is clearly evident that the incidence of NTDs have significantly reduced from 11.42/1000 births to 2.79/1000 births. In most of the previous studies NTDs had a female preponderance whereas present study has a male preponderance.In older studies, spina bifida was the most common NTDs followed by anencephaly. But in the present study anencephaly was the common NTD than spina bifida. Incidence of NTDs has reduced due to various reasons like prenatal screening for fetal anomalies and folic acid supplementation. PMID:26393168

  1. Program Specificity for Ptf1a in Pancreas versus Neural Tube Development Correlates with Distinct Collaborating Cofactors and Chromatin Accessibility

    PubMed Central

    Meredith, David M.; Borromeo, Mark D.; Deering, Tye G.; Casey, Bradford H.; Savage, Trisha K.; Mayer, Paul R.; Hoang, Chinh; Tung, Kuang-Chi; Kumar, Manonmani; Shen, Chengcheng; Swift, Galvin H.

    2013-01-01

    The lineage-specific basic helix-loop-helix transcription factor Ptf1a is a critical driver for development of both the pancreas and nervous system. How one transcription factor controls diverse programs of gene expression is a fundamental question in developmental biology. To uncover molecular strategies for the program-specific functions of Ptf1a, we identified bound genomic regions in vivo during development of both tissues. Most regions bound by Ptf1a are specific to each tissue, lie near genes needed for proper formation of each tissue, and coincide with regions of open chromatin. The specificity of Ptf1a binding is encoded in the DNA surrounding the Ptf1a-bound sites, because these regions are sufficient to direct tissue-restricted reporter expression in transgenic mice. Fox and Sox factors were identified as potential lineage-specific modifiers of Ptf1a binding, since binding motifs for these factors are enriched in Ptf1a-bound regions in pancreas and neural tube, respectively. Of the Fox factors expressed during pancreatic development, Foxa2 plays a major role. Indeed, Ptf1a and Foxa2 colocalize in embryonic pancreatic chromatin and can act synergistically in cell transfection assays. Together, these findings indicate that lineage-specific chromatin landscapes likely constrain the DNA binding of Ptf1a, and they identify Fox and Sox gene families as part of this process. PMID:23754747

  2. ‘Cut from the same cloth’: Shared microsatellite variants among cancers link to ectodermal tissues-neural tube and crest cells

    PubMed Central

    Bavarva, Jasmin H.; Wu, Xiaowei; Zhu, Hongxiao; Garner, Harold R.

    2015-01-01

    The pluripotent cells of the embryonic ectodermal tissues are known to be a precursor for multiple tumor types. The adaptability of these cells is a trait exploited by cancer. We previously described cancer-associated microsatellite loci (CAML) shared between glioblastoma (GBM) and lower-grade gliomas. Therefore, we hypothesized that these variants, identified from germline DNA, are shared by cancers from tissues originating from ectodermal tissues: neural tube cells (NTC) and crest cells (NCC). Using exome sequencing data from four cancers with origins to NTC and NCC, a ‘signature’ of loci significant to each cancer (p-value ? 0.01) was created and compared with previously identified CAML from breast cancer. The results of this analysis show that variant loci among the cancers with tissue origins from NTC/NCC were closely linked. Signaling pathways linked to genes with non-coding CAML genotypes revealed enriched connections to hereditary, neurological, and developmental disease or disorders. Thus, variants in genes from tissues initiating from NTC/NCC, if recurrently detected, may indicate a common etiology. Additionally, CAML genotypes from non-tumor DNA may predict cancer phenotypes and are common to shared embryonic tissues of origin. PMID:26246470

  3. Ectopic cross-talk between thyroid and retinoic acid signaling: A possible etiology for spinal neural tube defects.

    PubMed

    Li, Huili; Bai, Baoling; Zhang, Qin; Bao, Yihua; Guo, Jin; Chen, Shuyuan; Miao, Chunyue; Liu, Xiaozhen; Zhang, Ting

    2015-12-01

    Previous studies have highlighted the connections between neural tube defects (NTDs) and both thyroid hormones (TH) and vitamin A. However, whether the two hormonal signaling pathways interact in NTDs has remained unclear. We measured the expression levels of TH signaling genes in human fetuses with spinal NTDs associated with maternal hyperthyroidism as well as levels of retinoic acid (RA) signaling genes in mouse fetuses exposed to an overdose of RA using NanoString or real-time PCR on spinal cord tissues. Interactions between the two signaling pathways were detected by ChIP assays. The data revealed attenuated DIO2/DIO3 switching in fetuses with NTDs born to hyperthyroid mothers. The promoters of the RA signaling genes CRABP1 and RARB were ectopically occupied by increased RXRG and RXRB but displayed decreased levels of inhibitory histone modifications, suggesting that elevated TH signaling abnormally stimulates RA signaling genes. Conversely, in the mouse model, the observed decrease in Dio3 expression could be explained by increased levels of inhibitory histone modifications in the Dio3 promoter region, suggesting that overactive RA signaling may ectopically derepress TH signaling. This study thus raises in vivo a possible abnormal cross-promotion between two different hormonal signals through their common RXRs and the subsequent recruitment of histone modifications, prompting further investigation into their involvement in the etiology of spinal NTDs. PMID:26188161

  4. 'Cut from the same cloth': Shared microsatellite variants among cancers link to ectodermal tissues-neural tube and crest cells.

    PubMed

    Karunasena, Enusha; Mciver, Lauren J; Bavarva, Jasmin H; Wu, Xiaowei; Zhu, Hongxiao; Garner, Harold R

    2015-09-01

    The pluripotent cells of the embryonic ectodermal tissues are known to be a precursor for multiple tumor types. The adaptability of these cells is a trait exploited by cancer. We previously described cancer-associated microsatellite loci (CAML) shared between glioblastoma (GBM) and lower-grade gliomas. Therefore, we hypothesized that these variants, identified from germline DNA, are shared by cancers from tissues originating from ectodermal tissues: neural tube cells (NTC) and crest cells (NCC). Using exome sequencing data from four cancers with origins to NTC and NCC, a 'signature' of loci significant to each cancer (p-value ? 0.01) was created and compared with previously identified CAML from breast cancer. The results of this analysis show that variant loci among the cancers with tissue origins from NTC/NCC were closely linked. Signaling pathways linked to genes with non-coding CAML genotypes revealed enriched connections to hereditary, neurological, and developmental disease or disorders. Thus, variants in genes from tissues initiating from NTC/NCC, if recurrently detected, may indicate a common etiology. Additionally, CAML genotypes from non-tumor DNA may predict cancer phenotypes and are common to shared embryonic tissues of origin. PMID:26246470

  5. Not all cases of neural-tube defect can be prevented by increasing the intake of folic acid.

    PubMed

    Heseker, Helmut B; Mason, Joel B; Selhub, Jacob; Rosenberg, Irwin H; Jacques, Paul F

    2009-07-01

    Some countries have introduced mandatory folic acid fortification, whereas others support periconceptional supplementation of women in childbearing age. Several European countries are considering whether to adopt a fortification policy. Projections of the possible beneficial effects of increased folic acid intake assume that the measure will result in a considerable reduction in neural-tube defects (NTD) in the target population. Therefore, the objective of the present study is to evaluate the beneficial effects of different levels of folic acid administration on the prevalence of NTD. Countries with mandatory fortification achieved a significant increase in folate intake and a significant decline in the prevalence of NTD. This was also true for supplementation trials. However, the prevalence of NTD at birth declined to approximately five cases at birth per 10 000 births and seven to eight cases at birth or abortion per 10 000 births. This decline was independent of the amount of folic acid administered and apparently reveals a 'floor effect' for folic acid-preventable NTD. This clearly shows that not all cases of NTD are preventable by increasing the folate intake. The relative decline depends on the initial NTD rate. Countries with NTD prevalence close to the observed floor may have much smaller reductions in NTD rates with folic acid fortification. Additionally, potential adverse effects of fortification on other vulnerable population groups have to be seriously considered. Policy decisions concerning national mandatory fortification programmes must take into account realistically projected benefits as well as the evidence of risks to all vulnerable groups. PMID:19079944

  6. Maternal Consumption of Non-Staple Food in the First Trimester and Risk of Neural Tube Defects in Offspring

    PubMed Central

    Wang, Meng; Wang, Zhi-Ping; Gao, Li-Jie; Yang, Hui; Zhao, Zhong-Tang

    2015-01-01

    To study the associations between maternal consumption of non-staple food in the first trimester and risk of neural tube defects (NTDs) in offspring. Data collected from a hospital-based case-control study conducted between 2006 and 2008 in Shandong/Shanxi provinces including 459 mothers with NTDs-affected births and 459 mothers without NTDs-affected births. Logistic regression models were used to examine the associations between maternal consumption of non-staple food in the first trimester and risk of NTDs in offspring. The effects were evaluated by odds ratio (OR) and 95% confidence intervals (95% CIs) with SAS9.1.3.software. Maternal consumption of milk, fresh fruits and nuts in the first trimester were protective factors for total NTDs. Compared with consumption frequency of ?1 meal/week, the ORs for milk consumption frequency of 1–2, 3–6, ?7 meals/week were 0.50 (95% CI: 0.28–0.88), 0.56 (0.32–0.99), and 0.59 (0.38–0.90), respectively; the ORs for fresh fruits consumption frequency of 1–2, 3–6, ?7 meals/week were 0.29 (95% CI: 0.12–0.72), 0.22 (0.09–0.53), and 0.32 (0.14–0.71), respectively; the ORs for nuts consumption frequency of 1–2, 3–6, ?7 meals/week were 0.60 (95% CI: 0.38–0.94), 0.49 (0.31–0.79), and 0.63 (0.36–1.08), respectively. Different effects of above factors on NTDs were found for subtypes of anencephaly and spina bifida. Maternal non-staple food consumption of milk, fresh fruits and nuts in the first trimester was associated with reducing NTDs risk in offspring. PMID:25919306

  7. Validation of self-reported proximity to agricultural crops in a case-control study of neural tube defects.

    PubMed

    Rull, Rudolph P; Ritz, Beate; Shaw, Gary M

    2006-03-01

    Self-reported perinatal exposures to chemicals or pollutant sources in case-control studies of birth defects may be inaccurate due to misreporting among mothers. In a case-control study of neural tube defects delivered in California in 1987-1988, mothers of case and control infants were asked whether they lived within 0.25 mile (400 m) of agricultural crops. Responses were compared against a gold standard derived from historical agricultural land-use survey maps. The odds ratio for self-reported proximity to any crops (1.62, 95% confidence interval: 1.08, 2.43) appeared to be positively biased compared with the estimate for map-based proximity (1.17, 95% confidence interval: 0.79, 1.71). This pattern was also observed for proximity to specific crops such as nonpermanent and orchard crops. For vineyards, however, we observed an increased risk associated with map-based proximity (odds ratio=2.45, 95% confidence interval: 1.08, 5.58) but not with self-reported proximity (1.09, 95% confidence interval: 0.51, 2.34). The sensitivity of self-reported proximity to any crops was greater for case (65.7%) than control mothers (50.0%) while specificity was about the same for case and control mothers (87.5 vs. 89.3%), suggesting that control mothers under-reported proximity to crops. Differential reporting was also observed between geographic regions, urban and rural residents, and across levels of maternal employment and education. These results suggest differential reporting between case and control mothers as well as an influence from maternal demographic characteristics on reporting accuracy. PMID:16047039

  8. Developmental time rather than local environment regulates the schedule of epithelial polarization in the zebrafish neural rod

    E-print Network

    Girdler, Gemma C.; Araya, Claudio; Ren, Xiaoyun; Clarke, Jonathan D. W.

    2013-03-24

    Abstract Background Morphogenesis requires developmental processes to occur both at the right time and in the right place. During neural tube formation in the zebrafish embryo, the generation of the apical specializations of the lumen must occur...

  9. Neural underpinnings of background acoustic noise in normal aging and mild cognitive impairment.

    PubMed

    Sinanaj, Indrit; Montandon, Marie-Louise; Rodriguez, Cristelle; Herrmann, François; Santini, Francesco; Haller, Sven; Giannakopoulos, Panteleimon

    2015-12-01

    Previous contributions in younger cohorts have revealed that reallocation of cerebral resources, a crucial mechanism for working memory (WM), may be disrupted by parallel demands of background acoustic noise suppression. To date, no study has explored the impact of such disruption on brain activation in elderly individuals with or without subtle cognitive deficits. We performed a functional Magnetic Resonance Imaging (fMRI) study in 23 cases (mean age=75.7y.o., 16 men) with mild cognitive impairment (MCI) and 16 elderly healthy controls (HC, mean age=70.1y.o., three men) using a 2-back WM task, under two distinct MRI background acoustic noise conditions (louder vs. lower noise echo-planar imaging). General linear models were used to assess brain activation as a function of group and noise. In both groups, lower background noise is associated with increased activation of the working memory network (WMN). A decrease of the normally observed deactivation of the default mode network (DMN) is found under louder noise in both groups. Unlike HC, MCI cases also show decreased deactivation of the DMN under both louder and lower background noise. Under louder noise, this decrease is observed in anterior parts of the DMN in HC, and in the posterior cingulate cortex in MCI cases. Our results suggest that background acoustic noise has a differential impact on WMN activation in normal aging as a function of the cognitive status. Only louder noise has a disruptive effect on the usually observed DMN deactivation during WM task performance in HC. In contrast, MCI cases show altered DMN reactivity even in the presence of lower noise. PMID:26391923

  10. Ethanol-induced impairment of polyamine homeostasis – A potential cause of neural tube defect and intrauterine growth restriction in fetal alcohol syndrome

    SciTech Connect

    Haghighi Poodeh, Saeid; Alhonen, Leena; Salonurmi, Tuire; Savolainen, Markku J.

    2014-03-28

    Highlights: • Polyamine pools in embryonic and extraembryonic tissues are developmentally regulated. • Alcohol administration perturbs polyamine levels in the tissues with various patterns. • Total absence of polyamines in the embryo head at 9.5 dpc is critical for development. • The deficiency is associated with reduction in endothelial cell sprouting in the head. • Retarded migration of neural crest cells may cause development of neural tube defect. - Abstract: Introduction: Polyamines play a fundamental role during embryogenesis by regulating cell growth and proliferation and by interacting with RNA, DNA and protein. The polyamine pools are regulated by metabolism and uptake from exogenous sources. The use of certain inhibitors of polyamine synthesis causes similar defects to those seen in alcohol exposure e.g. retarded embryo growth and endothelial cell sprouting. Methods: CD-1 mice received two intraperitoneal injections of 3 g/kg ethanol at 4 h intervals 8.75 days post coitum (dpc). The fetal head, trunk, yolk sac and placenta were collected at 9.5 and 12.5 dpc and polyamine concentrations were determined. Results: No measurable quantity of polyamines could be detected in the embryo head at 9.5 dpc, 12 h after ethanol exposure. Putrescine was not detectable in the trunk of the embryo at that time, whereas polyamines in yolk sac and placenta were at control level. Polyamine deficiency was associated with slow cell growth, reduction in endothelial cell sprouting, an altered pattern of blood vessel network formation and consequently retarded migration of neural crest cells and growth restriction. Discussion: Our results indicate that the polyamine pools in embryonic and extraembryonic tissues are developmentally regulated. Alcohol administration, at the critical stage, perturbs polyamine levels with various patterns, depending on the tissue and its developmental stage. The total absence of polyamines in the embryo head at 9.5 dpc may explain why this stage is so vulnerable to the development of neural tube defect, and growth restriction, the findings previously observed in fetal alcohol syndrome.

  11. Neural Tube Defects

    MedlinePLUS

    ... Some can be harmful to a pregnancy, like air pollution, lead and cigarette smoke. Who is at risk ... Some can be harmful to a pregnancy, like air pollution, lead and cigarette smoke. Who is at risk ...

  12. Polymorphisms in MTHFD1 Gene and Susceptibility to Neural Tube Defects: A Case-Control Study in a Chinese Han Population with Relatively Low Folate Levels

    PubMed Central

    Wu, Jian; Bao, Yihua; Lu, Xiaolin; Wu, Lihua; Zhang, Ting; Guo, Jin; Yang, Jian

    2015-01-01

    Background The polymorphism of methylenetetrahydrofolate dehydrogenase (MTHFD1) has been reported as a risk factor for neural tube defects (NTDs). In the present study, we aimed to investigate whether the single-nucleotide polymorphisms (SNPs) of MTHFD1 gene are associated with NTDs in a Chinese population and to determine their mechanism of action. Material/Methods MTHFD1 gene was scanned in a total of 270 NTDs cases and 192 healthy controls by using next-generation sequencing (NGS) method. After quality control procedures, 208 selected SNP sites in MTHFD1 gene were enrolled for follow-up statistical association analyses. Functional analyses were also performed for significant SNPs through bioinformatics analysis. Folic acid levels of brain tissue in available NTDs cases and healthy controls (113 and 123, respectively) were measured. Statistical and bioinformatics analyses were performed to investigate the relationship between SNPs in MTHFD1 and susceptibility to NTDs. Results Statistical analysis showed that 2 independent SNPs, rs1956545 and rs56811449, confer the risk of NTDs (P value=0.0195, OR (odds ratio)=1.41, 95% CI (confidence interval)=1.06–1.88; P value=0.0107, OR=0.56, 95% CI=0.36–0.87). The haplotype GGGG, which consists of 4 SNPs (rs2236225, rs2236224, rs1256146, and rs6573559), is also associated with risk of NTDs (P value=0.0438, OR=0.7180, 95% CI=0.5214–0.9888). The risk allele C of rs1956545 is also associated with decreased folic acid levels in the brain (P value=0.0222, standard beta=?0.2238, 95% CI=?0.4128 – ?0.0349) according to analysis in the subset of NTDs cases and healthy controls. Bioinformatics analysis indicates that rs1956545 and rs56811449 are within ENCODE regulatory regions, the open chromatin regions of blastula Trophoblast cell line, and histone-marked region of brain astrocyte cell line. Conclusions The polymorphism of SNP loci rs1956545 and rs56811449 as well as a haplotype in MTHFD1 gene could serve as an indicator for the occurrence of NTDs in Chinese population and some specific genotypes of the loci may have lower risk of developing NTDs. PMID:26343515

  13. Neural tube defects on the Texas-Mexico border: what we've learned in the 20 years since the Brownsville cluster.

    PubMed

    Suarez, Lucina; Felkner, Marilyn; Brender, Jean D; Canfield, Mark; Zhu, Huiping; Hendricks, Katherine A

    2012-11-01

    We reviewed the published findings from the Texas Neural Tube Defect Project, a 6-year case-control study (1995-2000) of neural tube defects (NTDs) on the Texas-Mexico border. In this review, we highlight what was learned about environmental, genetic, and nutritional factors (i.e., those related to the folate and other metabolic pathways) and the novel putative risk factors that emerged from this study of Mexican American women living on the Texas-Mexico border. Our investigations of the micronutrients and metabolic pathways involved confirmed the findings of other researchers that increased folate intake has a protective effect and that low serum B(12) , high serum homocysteine levels, and obesity independently contribute to risk. Studies of this population also have implicated hyperinsulinemia and low ferritin, metabolic risk factors, which require additional study to elucidate their physiologic mechanism. Environmental contaminants such as heavy metals, pesticides, and polychlorinated biphenyls (PCBs), which were of community concern, did little to explain NTD risk. Studies in this folic acid deficit-population also revealed several novel risk factors, namely, diarrhea, stress, fumonisins, and the combination of nitrosatable drug exposure with high nitrate/nitrite intake. In conclusion, the 23 studies among the Mexican American women living along the Texas-Mexico border have demonstrated the multifactorial nature of NTDs and that a population deficient in folic acid will be vulnerable to a variety of insults whether brought on by individual behaviors (e.g., obesity) or through the surrounding environment (e.g., fumonisins). Birth Defects Research (Part A), 2012. © 2012 Wiley Periodicals, Inc. PMID:22945287

  14. Single-tube multiplexed molecular detection of endemic porcine viruses in combination with background screening for transboundary diseases.

    PubMed

    Wernike, Kerstin; Hoffmann, Bernd; Beer, Martin

    2013-03-01

    Detection of several pathogens with multiplexed real-time quantitative PCR (qPCR) assays in a one-step setup allows the simultaneous detection of two endemic porcine and four different selected transboundary viruses. Reverse transcription (RT)-qPCR systems for the detection of porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2), two of the most economically important pathogens of swine worldwide, were combined with a screening system for diseases notifiable to the World Organization of Animal Health, namely, classical and African swine fever, foot-and-mouth disease, and Aujeszky's disease. Background screening was implemented using the identical fluorophore for all four different RT-qPCR assays. The novel multiplex RT-qPCR system was validated with a large panel of different body fluids and tissues from pigs and other animal species. Both reference samples and clinical specimens were used for a complete evaluation. It could be demonstrated that a highly sensitive and specific parallel detection of the different viruses was possible. The assays for the notifiable diseases were even not affected by the simultaneous amplification of very high loads of PRRSV- and PCV2-specific sequences. The novel broad-spectrum multiplex assay allows in a unique form the routine investigation for endemic porcine pathogens with exclusion diagnostics of the most important transboundary diseases in samples from pigs with unspecific clinical signs, such as fever or hemorrhages. The new system could significantly improve early detection of the most important notifiable diseases of swine and could lead to a new approach in syndromic surveillance. PMID:23303496

  15. Survey of prenatal screening policies in Europe for structural malformations and chromosome anomalies, and their impact on detection and termination rates for neural tube defects and Down's syndrome

    PubMed Central

    Boyd, PA; DeVigan, C; Khoshnood, B; Loane, M; Garne, E; Dolk, H

    2008-01-01

    Objective To ‘map’ the current (2004) state of prenatal screening in Europe. Design (i) Survey of country policies and (ii) analysis of data from EUROCAT (European Surveillance of Congenital Anomalies) population-based congenital anomaly registers. Setting Europe. Population Survey of prenatal screening policies in 18 countries and 1.13 million births in 12 countries in 2002–04. Methods (i) Questionnaire on national screening policies and termination of pregnancy for fetal anomaly (TOPFA) laws in 2004. (ii) Analysis of data on prenatal detection and termination for Down's syndrome and neural tube defects (NTDs) using the EUROCAT database. Main outcome measures Existence of national prenatal screening policies, legal gestation limit for TOPFA, prenatal detection and termination rates for Down's syndrome and NTD. Results Ten of the 18 countries had a national country-wide policy for Down's syndrome screening and 14/18 for structural anomaly scanning. Sixty-eight percent of Down's syndrome cases (range 0–95%) were detected prenatally, of which 88% resulted in termination of pregnancy. Eighty-eight percent (range 25–94%) of cases of NTD were prenatally detected, of which 88% resulted in termination. Countries with a first-trimester screening policy had the highest proportion of prenatally diagnosed Down's syndrome cases. Countries with no official national Down's syndrome screening or structural anomaly scan policy had the lowest proportion of prenatally diagnosed Down's syndrome and NTD cases. Six of the 18 countries had a legal gestational age limit for TOPFA, and in two countries, termination of pregnancy was illegal at any gestation. Conclusions There are large differences in screening policies between countries in Europe. These, as well as organisational and cultural factors, are associated with wide country variation in prenatal detection rates for Down's syndrome and NTD. Please cite this paper as: Boyd P, DeVigan C, Khoshnood B, Loane M, Garne E, Dolk H, and the EUROCAT working group. Survey of prenatal screening policies in Europe for structural malformations and chromosome anomalies, and their impact on detection and termination rates for neural tube defects and Down's syndrome. BJOG 2008;115:689–696. PMID:18410651

  16. GMDH-type neural network modeling and genetic algorithm-based multi-objective optimization of thermal and friction characteristics in heat exchanger tubes with wire-rod bundles

    NASA Astrophysics Data System (ADS)

    Rahimi, Masoud; Beigzadeh, Reza; Parvizi, Mehdi; Eiamsa-ard, Smith

    2015-09-01

    The group method of data handling (GMDH) technique was used to predict heat transfer and friction characteristics in heat exchanger tubes equipped with wire-rod bundles. Nusselt number and friction factor were determined as functions of wire-rod bundle geometric parameters and Reynolds number. The performance of the developed GMDH-type neural networks was found to be superior in comparison with the proposed empirical correlations. For optimization, the genetic algorithm-based multi-objective optimization was applied.

  17. Identification of PCSK9 as a novel serum biomarker for the prenatal diagnosis of neural tube defects using iTRAQ quantitative proteomics.

    PubMed

    An, Dong; Wei, Xiaowei; Li, Hui; Gu, Hui; Huang, Tianchu; Zhao, Guifeng; Liu, Bo; Wang, Weilin; Chen, Lizhu; Ma, Wei; Zhang, Henan; Cao, Songying; Yuan, Zhengwei

    2015-01-01

    To identify candidate serum molecule biomarkers for the non-invasive early prenatal diagnosis of neural tube defects (NTDs), we employed an iTRAQ-based quantitative proteomic approach to analyze the proteomic changes in serum samples from embryonic day (E) 11 and E13 pregnant rats with spina bifida aperta (SBA) induced by all-trans retinoic acid. Among the 390 proteins identified, 40 proteins at E11 and 26 proteins at E13 displayed significant differential expression in the SBA groups. We confirmed 5 candidate proteins by ELISA. We observed the space-time expression changes of proprotein convertase subtilisin/kexin type 9 (PCSK9) at different stages of fetal development, including a marked decrease in the sera of NTD pregnancies and gradual increase in the sera of normal pregnancies with embryonic development. PCSK9 demonstrated the diagnostic efficacy of potential NTD biomarkers [with an area under the receiver operating characteristic curve of 0.763, 95% CI: 065-0.88]. Additionally, PCSK9 expression in the spinal cords and placentas of SBA rat fetuses was markedly decreased. PCSK9 could serve as a novel molecular biomarker for the non-invasive prenatal screening of NTDs and may be involved in the pathogenesis of NTDs at critical periods of fetal development. PMID:26691006

  18. Levels of PAH-DNA Adducts in Placental Tissue and the Risk of Fetal Neural Tube Defects in a Chinese Population

    PubMed Central

    Yuan, Yue; Jin, Lei; Wang, Linlin; Li, Zhiwen; Zhang, Le; Zhu, Huiping; Finnell, Richard H; Zhou, Guodong; Ren, Aiguo

    2014-01-01

    We examined the relationship between PAH-DNA adduct levels in the placental tissue, measured by a highly sensitive 32P-postlabeling assay, and the risk of fetal neural tube defects (NTDs). We further explored the interaction between PAH-DNA adducts and placental PAHs with respect to NTD risk. Placental tissues from 80 NTD-affected pregnancies and 50 uncomplicated normal pregnancies were included in this case-control study. Levels of PAH-DNA adducts were lower in the NTD group (8.12 per 108 nucleotides) compared to controls (9.92 per 108 nucleotides). PAH-DNA adduct concentrations below the median was associated with a 3-fold increased NTD risk. Women with a low PAH-DNA adduct level in concert with a high placental PAH level resulted in a 10-fold elevated risk of having an NTD-complicated pregnancy. A low level of placental PAH-DNA adducts was associated with an increased risk of NTDs; this risk increased dramatically when a low adduct level was coupled with a high placental PAH concentration. PMID:23416326

  19. Identification of PCSK9 as a novel serum biomarker for the prenatal diagnosis of neural tube defects using iTRAQ quantitative proteomics

    PubMed Central

    An, Dong; Wei, Xiaowei; Li, Hui; Gu, Hui; Huang, Tianchu; Zhao, Guifeng; Liu, Bo; Wang, Weilin; Chen, Lizhu; Ma, Wei; Zhang, Henan; Cao, Songying; Yuan, Zhengwei

    2015-01-01

    To identify candidate serum molecule biomarkers for the non-invasive early prenatal diagnosis of neural tube defects (NTDs), we employed an iTRAQ-based quantitative proteomic approach to analyze the proteomic changes in serum samples from embryonic day (E) 11 and E13 pregnant rats with spina bifida aperta (SBA) induced by all-trans retinoic acid. Among the 390 proteins identified, 40 proteins at E11 and 26 proteins at E13 displayed significant differential expression in the SBA groups. We confirmed 5 candidate proteins by ELISA. We observed the space-time expression changes of proprotein convertase subtilisin/kexin type 9 (PCSK9) at different stages of fetal development, including a marked decrease in the sera of NTD pregnancies and gradual increase in the sera of normal pregnancies with embryonic development. PCSK9 demonstrated the diagnostic efficacy of potential NTD biomarkers [with an area under the receiver operating characteristic curve of 0.763, 95% CI: 065–0.88]. Additionally, PCSK9 expression in the spinal cords and placentas of SBA rat fetuses was markedly decreased. PCSK9 could serve as a novel molecular biomarker for the non-invasive prenatal screening of NTDs and may be involved in the pathogenesis of NTDs at critical periods of fetal development. PMID:26691006

  20. Folic acid and the prevention of neural tube defects: A survey of awareness among Latina women of childbearing age residing in southeast Michigan.

    PubMed

    Kannan, Srimathi; Menotti, Elaine; Scherer, Holly K; Dickinson, Jennifer; Larson, Kimberly

    2007-01-01

    Periconceptional intake of folic acid is known to reduce the risk for neural tube defects (NTDs). To inform southeast Michigan Latina women of childbearing age about the benefits of food and supplemental sources of the micronutrient in the prevention of NTDs, Spanish-English bilingual health educators carried out 20 education events in supermarkets and community organizations serving Latina women. One hundred and sixty Latina women ages 19 to 50 years indicated their current folic acid awareness and stated their future intentions regarding folic acid. Of 160 women surveyed, 114 (71%) had heard of folic acid, 84 (74%) knew that folic acid prevents birth defects, 63 (55%) knew the critical time to take folic acid, and 76 (67%) identified at least one source of folic acid. After participating in the education events, 136 women (85%) reported planning to eat more folate and/or folic acid-rich foods. Although general folic acid awareness is fairly high, health promotion efforts must be coordinated at community locations serving Latina women to share folic acid's specific protective effects in the prevention of NTDs, the critical timing of intake, and its food and supplement sources. PMID:16840767

  1. Organochlorine Pesticide Levels in Maternal Serum and Risk of Neural Tube Defects in Offspring in Shanxi Province, China: A Case-Control Study

    PubMed Central

    Wang, Bin; Yi, Deqing; Jin, Lei; Li, Zhiwen; Liu, Jufen; Zhang, Yali; Qiu, Xinghua; Liu, Wenxin; Tao, Shu; Ren, Aiguo

    2014-01-01

    Organochlorine pesticides (OCPs) in placental tissue have been reported to be associated with an increased risk for fetal neural tube defects (NTDs). Our case-control study was performed to explore the association between maternal serum OCP concentration and NTD risk in offspring. Serum samples were collected from 117 mothers who delivered NTD infants (case group) and 121 mothers who delivered healthy infants (control group). Only three of the 25 OCPs were detected in more than half of the maternal serum samples. The median concentration of total OCPs in the case group was significantly higher than that of the control group. However, no dose-response relationships between higher levels of any individual OCP or total OCPs and the risk of NTDs or subtypes were observed in either the unadjusted binary unconditional logistic regression model or the model adjusted by potential confounders. We conclude that no clear association between maternal serum OCP residues and NTD risk in offspring was observed in this population. PMID:24911776

  2. Abnormal epigenetic regulation of the gene expression levels of Wnt2b and Wnt7b: Implications for neural tube defects.

    PubMed

    Bai, Baoling; Chen, Shuyuan; Zhang, Qin; Jiang, Qian; Li, Huili

    2016-01-01

    The association between Wnt genes and neural tube defects (NTDs) is recognized, however, it remains to be fully elucidated. Our previous study demonstrated that epigenetic mechanisms are affected in human NTDs. Therefore, the present study aimed to evaluate whether Wnt2b and Wnt7b are susceptible to abnormal epigenetic modification in NTDs, using chromatin immunoprecipitation assays to evaluate histone enrichments and the MassARRAY platform to detect the methylation levels of target regions within Wnt genes. The results demonstrated that the transcriptional activities of Wnt2b and Wnt7b were abnormally upregulated in mouse fetuses with NTDs and, in the GC?rich promoters of these genes, histone 3 lysine 4 (H3K4) acetylation was enriched, whereas H3K27 trimethylation was reduced. Furthermore, several CpG sites in the altered histone modification of target regions were significantly hypomethylated. The present study also detected abnormal epigenetic modifications of these Wnt genes in human NTDs. In conclusion, the present study detected abnormal upregulation in the levels of Wnt2b and Wnt7b, and hypothesized that the alterations may be due to the ectopic opening of chromatin structure. These results improve understanding of the dysregulation of epigenetic modification of Wnt genes in NTDs. PMID:26548512

  3. Abnormal epigenetic regulation of the gene expression levels of Wnt2b and Wnt7b: Implications for neural tube defects

    PubMed Central

    BAI, BAOLING; CHEN, SHUYUAN; ZHANG, QIN; JIANG, QIAN; LI, HUILI

    2016-01-01

    The association between Wnt genes and neural tube defects (NTDs) is recognized, however, it remains to be fully elucidated. Our previous study demonstrated that epigenetic mechanisms are affected in human NTDs. Therefore, the present study aimed to evaluate whether Wnt2b and Wnt7b are susceptible to abnormal epigenetic modification in NTDs, using chromatin immunoprecipitation assays to evaluate histone enrichments and the MassARRAY platform to detect the methylation levels of target regions within Wnt genes. The results demonstrated that the transcriptional activities of Wnt2b and Wnt7b were abnormally upregulated in mouse fetuses with NTDs and, in the GC-rich promoters of these genes, histone 3 lysine 4 (H3K4) acetylation was enriched, whereas H3K27 trimethylation was reduced. Furthermore, several CpG sites in the altered histone modification of target regions were significantly hypomethylated. The present study also detected abnormal epigenetic modifications of these Wnt genes in human NTDs. In conclusion, the present study detected abnormal upregulation in the levels of Wnt2b and Wnt7b, and hypothesized that the alterations may be due to the ectopic opening of chromatin structure. These results improve understanding of the dysregulation of epigenetic modification of Wnt genes in NTDs. PMID:26548512

  4. Mesoderm is required for coordinated cell movements within zebrafish neural plate in vivo

    PubMed Central

    2014-01-01

    Background Morphogenesis of the zebrafish neural tube requires the coordinated movement of many cells in both time and space. A good example of this is the movement of the cells in the zebrafish neural plate as they converge towards the dorsal midline before internalizing to form a neural keel. How these cells are regulated to ensure that they move together as a coherent tissue is unknown. Previous work in other systems has suggested that the underlying mesoderm may play a role in this process but this has not been shown directly in vivo. Results Here we analyze the roles of subjacent mesoderm in the coordination of neural cell movements during convergence of the zebrafish neural plate and neural keel formation. Live imaging demonstrates that the normal highly coordinated movements of neural plate cells are lost in the absence of underlying mesoderm and the movements of internalization and neural tube formation are severely disrupted. Despite this, neuroepithelial polarity develops in the abnormal neural primordium but the resulting tissue architecture is very disorganized. Conclusions We show that the movements of cells in the zebrafish neural plate are highly coordinated during the convergence and internalization movements of neurulation. Our results demonstrate that the underlying mesoderm is required for these coordinated cell movements in the zebrafish neural plate in vivo. PMID:24755297

  5. Ear Tubes

    MedlinePLUS

    ... Meeting Calendar Find an ENT Doctor Near You Ear Tubes Ear Tubes Patient Health Information News media ... and throat specialist) may be considered. What are ear tubes? Ear tubes are tiny cylinders placed through ...

  6. Feeding Tubes

    MedlinePLUS

    ... administer the TPN. Tubes Used for Enteral Feeds NG (Nasogastric Tube) A flexible tube is placed via ... down through the esophagus into the stomach. The NG tube can be used to empty the stomach ...

  7. Massive-training artificial neural network (MTANN) for reduction of false positives in computer-aided detection of polyps: Suppression of rectal tubes

    SciTech Connect

    Suzuki, Kenji; Yoshida, Hiroyuki; Naeppi, Janne; Dachman, Abraham H.

    2006-10-15

    One of the limitations of the current computer-aided detection (CAD) of polyps in CT colonography (CTC) is a relatively large number of false-positive (FP) detections. Rectal tubes (RTs) are one of the typical sources of FPs because a portion of a RT, especially a portion of a bulbous tip, often exhibits a cap-like shape that closely mimics the appearance of a small polyp. Radiologists can easily recognize and dismiss RT-induced FPs; thus, they may lose their confidence in CAD as an effective tool if the CAD scheme generates such ''obvious'' FPs due to RTs consistently. In addition, RT-induced FPs may distract radiologists from less common true positives in the rectum. Therefore, removal RT-induced FPs as well as other types of FPs is desirable while maintaining a high sensitivity in the detection of polyps. We developed a three-dimensional (3D) massive-training artificial neural network (MTANN) for distinction between polyps and RTs in 3D CTC volumetric data. The 3D MTANN is a supervised volume-processing technique which is trained with input CTC volumes and the corresponding ''teaching'' volumes. The teaching volume for a polyp contains a 3D Gaussian distribution, and that for a RT contains zeros for enhancement of polyps and suppression of RTs, respectively. For distinction between polyps and nonpolyps including RTs, a 3D scoring method based on a 3D Gaussian weighting function is applied to the output of the trained 3D MTANN. Our database consisted of CTC examinations of 73 patients, scanned in both supine and prone positions (146 CTC data sets in total), with optical colonoscopy as a reference standard for the presence of polyps. Fifteen patients had 28 polyps, 15 of which were 5-9 mm and 13 were 10-25 mm in size. These CTC cases were subjected to our previously reported CAD scheme that included centerline-based segmentation of the colon, shape-based detection of polyps, and reduction of FPs by use of a Bayesian neural network based on geometric and texture features. Application of this CAD scheme yielded 96.4% (27/28) by-polyp sensitivity with 3.1 (224/73) FPs per patient, among which 20 FPs were caused by RTs. To eliminate the FPs due to RTs and possibly other normal structures, we trained a 3D MTANN with ten representative polyps and ten RTs, and applied the trained 3D MTANN to the above CAD true- and false-positive detections. In the output volumes of the 3D MTANN, polyps were represented by distributions of bright voxels, whereas RTs and other normal structures partly similar to RTs appeared as darker voxels, indicating the ability of the 3D MTANN to suppress RTs as well as other normal structures effectively. Application of the 3D MTANN to the CAD detections showed that the 3D MTANN eliminated all RT-induced 20 FPs, as well as 53 FPs due to other causes, without removal of any true positives. Overall, the 3D MTANN was able to reduce the FP rate of the CAD scheme from 3.1 to 2.1 FPs per patient (33% reduction), while the original by-polyp sensitivity of 96.4% was maintained.

  8. What Are Neural Tube Defects?

    MedlinePLUS

    ... are born with spina bifida will have normal intelligence, but some will have learning or intellectual disabilities . ... effects, some children with this condition have normal intelligence. 6 Iniencephaly Iniencephaly(pronounced in-ee-ehn-SEF- ...

  9. Feeding tube insertion - gastrostomy

    MedlinePLUS

    ... tube insertion; G-tube insertion; PEG tube insertion; Stomach tube insertion; Percutaneous endoscopic gastrostomy tube insertion ... and down the esophagus, which leads to the stomach. After the endoscopy tube is inserted, the skin ...

  10. Nasogastric feeding tube

    MedlinePLUS

    Feeding - nasogastric tube; NG tube; Bolus feeding; Continuous pump feeding; Gavage tube ... A nasogastric tube (NG tube) is a special tube that carries food and medicine to the stomach through the nose. It can be ...

  11. Gastrostomy Tube (G-Tube)

    MedlinePLUS

    ... warmth at the tube site; discharge that's yellow, green, or foul-smelling; fever) excessive bleeding or drainage from the tube site severe abdominal pain persistent vomiting or diarrhea trouble passing gas or having a bowel movement pink-red tissue (called granulation tissue) coming out ...

  12. Multiple tube premixing device

    DOEpatents

    Uhm, Jong Ho; Varatharajan, Balachandar; Ziminsky, Willy Steve; Kraemer, Gilbert Otto; Yilmaz, Ertan; Lacy, Benjamin; Stevenson, Christian; Felling, David

    2012-12-11

    The present application provides a premixer for a combustor. The premixer may include a fuel plenum with a number of fuel tubes and a burner tube with a number of air tubes. The fuel tubes extend about the air tubes.

  13. Multiple tube premixing device

    DOEpatents

    Uhm, Jong Ho; Naidu, Balachandar; Ziminksy, Willy Steve; Kraemer, Gilbert Otto; Yilmaz, Ertan; Lacy, Benjamin; Stevenson, Christian; Felling, David

    2013-08-13

    The present application provides a premixer for a combustor. The premixer may include a fuel plenum with a number of fuel tubes and a burner tube with a number of air tubes. The fuel tubes extend about the air tubes.

  14. Thermal neutron background measurement in CJPL

    NASA Astrophysics Data System (ADS)

    Zeng, Z. M.; Gong, H.; Yue, Q.; Li, J. M.

    2015-12-01

    This paper describes the measurement of thermal neutron flux in the CJPL underground laboratory in the proximity of the CDEX experiment. A low background thermal neutron detection system is designed which applies a combination of a 3He proportional tube and a 4He proportional tube as the detector. Thermal neutrons can be captured by the 3He proportional tube while the 4He proportional tube is for the purpose of background measurement. The tube wall is made up of oxygen-free copper to reduce the background due to radioactivity of the wall material. The electronics readout system has been developed to store triggered events' waveforms so as to get the amplitude spectrum and monitor the data quality. We observed an average thermal neutron flux of ? = 4.00 ± 0.08 ×10-6 /cm2 s in the CJPL experiment hall in the proximity of CDEX experiment and the neutron and background events both distribute uniformly along the tube.

  15. Electron tube

    DOEpatents

    Suyama, Motohiro (Hamamatsu, JP); Fukasawa, Atsuhito (Hamamatsu, JP); Arisaka, Katsushi (Los Angeles, CA); Wang, Hanguo (North Hills, CA)

    2011-12-20

    An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

  16. Neutron tubes

    DOEpatents

    Leung, Ka-Ngo (Hercules, CA); Lou, Tak Pui (Berkeley, CA); Reijonen, Jani (Oakland, CA)

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  17. Tapered pulse tube for pulse tube refrigerators

    DOEpatents

    Swift, Gregory W. (Sante Fe, NM); Olson, Jeffrey R. (San Mateo, CA)

    1999-01-01

    Thermal insulation of the pulse tube in a pulse-tube refrigerator is maintained by optimally varying the radius of the pulse tube to suppress convective heat loss from mass flux streaming in the pulse tube. A simple cone with an optimum taper angle will often provide sufficient improvement. Alternatively, the pulse tube radius r as a function of axial position x can be shaped with r(x) such that streaming is optimally suppressed at each x.

  18. The olfactory sensory system develops from coordinated movements within the neural plate

    PubMed Central

    Torres-Paz, Jorge

    2014-01-01

    Background The peripheral olfactory sensory system arises from morphologically identifiable structures called placodes. Placodes are relatively late developing structures, evident only well after the initiation of somitogenesis. Placodes are generally described as being induced from the ectoderm suggesting that their development is separate from the coordinated cell movements generating the central nervous system. Results With the advent of modern techniques it is possible to follow the development of the neurectoderm giving rise to the anterior neural tube, including the olfactory placodes. The cell movements giving rise to the optic cup are coordinated with those generating the olfactory placodes and adjacent telencephalon. The formation of the basal lamina separating the placode from the neural tube is coincident with the anterior migration of cranial neural crest. Conclusions Olfactory placodes are transient morphological structures arising from a continuous sheet of neurectoderm that gives rise to the peripheral and central nervous system. This field of cells is specified at the end of gastrulation and not secondarily induced from ectoderm. The separation of olfactory placodes and telencephalon occurs through complex cell movements within the developing neural plate similar to that observed for the developing optic cup. PMID:25255735

  19. Tube-in-tube thermophotovoltaic generator

    DOEpatents

    Ashcroft, John (Scotia, NY); Campbell, Brian (Scotia, NY); DePoy, David (Clifton Park, NY)

    1998-01-01

    A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell.

  20. Neural Networks

    E-print Network

    Jordan, Michael I.

    1996-03-13

    We present an overview of current research on artificial neural networks, emphasizing a statistical perspective. We view neural networks as parameterized graphs that make probabilistic assumptions about data, and view ...

  1. Chest tube insertion

    MedlinePLUS

    ... chest tube is removed. Patients may occasionally go home with a chest tube. While the chest tube is in place, your nurses will carefully check for air leaks, breathing problems, and if you need oxygen. They will also make sure the tube stays ...

  2. Neural crest contributions to the lamprey head

    NASA Technical Reports Server (NTRS)

    McCauley, David W.; Bronner-Fraser, Marianne

    2003-01-01

    The neural crest is a vertebrate-specific cell population that contributes to the facial skeleton and other derivatives. We have performed focal DiI injection into the cranial neural tube of the developing lamprey in order to follow the migratory pathways of discrete groups of cells from origin to destination and to compare neural crest migratory pathways in a basal vertebrate to those of gnathostomes. The results show that the general pathways of cranial neural crest migration are conserved throughout the vertebrates, with cells migrating in streams analogous to the mandibular and hyoid streams. Caudal branchial neural crest cells migrate ventrally as a sheet of cells from the hindbrain and super-pharyngeal region of the neural tube and form a cylinder surrounding a core of mesoderm in each pharyngeal arch, similar to that seen in zebrafish and axolotl. In addition to these similarities, we also uncovered important differences. Migration into the presumptive caudal branchial arches of the lamprey involves both rostral and caudal movements of neural crest cells that have not been described in gnathostomes, suggesting that barriers that constrain rostrocaudal movement of cranial neural crest cells may have arisen after the agnathan/gnathostome split. Accordingly, neural crest cells from a single axial level contributed to multiple arches and there was extensive mixing between populations. There was no apparent filling of neural crest derivatives in a ventral-to-dorsal order, as has been observed in higher vertebrates, nor did we find evidence of a neural crest contribution to cranial sensory ganglia. These results suggest that migratory constraints and additional neural crest derivatives arose later in gnathostome evolution.

  3. Nasogastric and Enteral Feeding Tubes GI/GU Nasogastric Tubes

    E-print Network

    Kay, Mark A.

    Nasogastric and Enteral Feeding Tubes GI/GU Nasogastric Tubes: Kendall Argyle Salem tube can should be high enough to evacuate the tube. 10 kg = 35-50 mmHg Nasogastric enteral feeding tubes: Kendall Curity Feeding Tube Sizes: 5FR. and 8 FR. VIASYS Enteral Feeding Tubes

  4. Torsion Tests of Tubes

    NASA Technical Reports Server (NTRS)

    Stang, Ambrose H; Ramberg, Walter; Back, Goldie

    1937-01-01

    This report presents the results of tests of 63 chromium-molybdenum steel tubes and 102 17st aluminum-alloy tubes of various sizes and lengths made to study the dependence of the torsional strength on both the dimensions of the tube and the physical properties of the tube material. Three types of failure are found to be important for sizes of tubes frequently used in aircraft construction: (1) failure by plastic shear, in which the tube material reached its yield strength before the critical torque was reached; (2) failure by elastic two-lobe buckling, which depended only on the elastic properties of the tube material and the dimensions of the tube; and (3) failure by a combination of (1) and (2) that is, by buckling taking place after some yielding of the tube material.

  5. Regulation of the nascent brain vascular network by neural progenitors.

    PubMed

    Santhosh, Devi; Huang, Zhen

    2015-11-01

    Neural progenitors are central players in the development of the brain neural circuitry. They not only produce the diverse neuronal and glial cell types in the brain, but also guide their migration in this process. Recent evidence indicates that neural progenitors also play a critical role in the development of the brain vascular network. At an early stage, neural progenitors have been found to facilitate the ingression of blood vessels from outside the neural tube, through VEGF and canonical Wnt signaling. Subsequently, neural progenitors directly communicate with endothelial cells to stabilize nascent brain vessels, in part through down-regulating Wnt pathway activity. Furthermore, neural progenitors promote nascent brain vessel integrity, through integrin ?v?8-dependent TGF? signaling. In this review, we will discuss the evidence for, as well as questions that remain, regarding these novel roles of neural progenitors and the underlying mechanisms in their regulation of the nascent brain vascular network. PMID:26163231

  6. Brightness enhancement seen through a tube.

    PubMed

    Spillmann, Lothar; Hardy, Joe; Delahunt, Peter; Pinna, Baingio; Werner, John S

    2010-01-01

    We report a fascinating phenomenon that emerges when a surface is viewed through a tube held close to one eye, with the other eye open. The disk-shaped area seen through the tube looks strikingly brighter and, when viewed on a textured background, also of higher spatial contrast than the same surface area viewed without a tube. The effect is reminiscent of a spotlight illuminating the area under consideration. We call this the 'tube effect'. The tube effect is one of the strongest contrast illusions known to us. It requires a matching luminance that is twice as high as the reference luminance seen through the tube. Brightness ratings increase linearly with the log of the background luminance. The effect (i) produces a dark afterimage, (ii) reverses in polarity with low ambient illumination, (iii) assumes the complementary colour of the illuminant, and (iv) persists with fully dilated pupils. Potential explanations include simultaneous contrast (due to the penumbra and dark inner walls of the tube) and veiling of the surround (due to local adaptation and a lower gain factor). PMID:21313947

  7. Introduction Background

    E-print Network

    Petta, Jason

    Research Conclusions #12;Background What is a hygrometer? VCSEL Chilled mirror hygrometer Why measure does a VCSEL hygrometer address these problems? 25Hz measurements Open source environment Low wind with chilled mirror hygrometer Pressure and Temperature effects #12;Calibration Techniques Removal of all

  8. Neural networks for triggering

    SciTech Connect

    Denby, B. ); Campbell, M. ); Bedeschi, F. ); Chriss, N.; Bowers, C. ); Nesti, F. )

    1990-01-01

    Two types of neural network beauty trigger architectures, based on identification of electrons in jets and recognition of secondary vertices, have been simulated in the environment of the Fermilab CDF experiment. The efficiencies for B's and rejection of background obtained are encouraging. If hardware tests are successful, the electron identification architecture will be tested in the 1991 run of CDF. 10 refs., 5 figs., 1 tab.

  9. Microhole Tubing Bending Report

    DOE Data Explorer

    Oglesby, Ken

    2012-01-01

    A downhole tubing bending study was made and is reported herein. IT contains a report and 2 excel spreadsheets to calculate tubing bending and to estimate contact points of the tubing to the drilled hole wall (creating a new support point).

  10. Evolvable synthetic neural system

    NASA Technical Reports Server (NTRS)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  11. Telescoping tube assembly

    NASA Technical Reports Server (NTRS)

    Sturm, Albert J. (Inventor); Marrinan, Thomas E. (Inventor)

    1995-01-01

    An extensible and retractable telescoping tube positions test devices that inspect large stationary objects. The tube has three dimensional adjustment capabilities and is vertically suspended from a frame. The tube sections are independently supported with each section comprising U-shaped housing secured to a thicker support plate. Guide mechanisms preferably mounted only to the thicker plates guide each tube section parallel to a reference axis with improved accuracy so that the position of the remote end of the telescoping tube is precisely known.

  12. Foundations of Artificial Intelligence Neural Networks

    E-print Network

    Qu, Rong

    Foundations of Artificial Intelligence Neural Networks Building Artificial Brains #12;Background of observed examples (training data). #12;Neural Networks Objectives Show how the human brain works Introduction The Human Brain (How a neuron works) Building Artificial Neurons Network Architecture and Learning

  13. Pediatric cuffed endotracheal tubes.

    PubMed

    Bhardwaj, Neerja

    2013-01-01

    Endotracheal intubation in children is usually performed utilizing uncuffed endotracheal tubes for conduct of anesthesia as well as for prolonged ventilation in critical care units. However, uncuffed tubes may require multiple changes to avoid excessive air leak, with subsequent environmental pollution making the technique uneconomical. In addition, monitoring of ventilatory parameters, exhaled volumes, and end-expiratory gases may be unreliable. All these problems can be avoided by use of cuffed endotracheal tubes. Besides, cuffed endotracheal tubes may be of advantage in special situations like laparoscopic surgery and in surgical conditions at risk of aspiration. Magnetic resonance imaging (MRI) scans in children have found the narrowest portion of larynx at rima glottides. Cuffed endotracheal tubes, therefore, will form a complete seal with low cuff pressure of <15 cm H2O without any increase in airway complications. Till recently, the use of cuffed endotracheal tubes was limited by variations in the tube design marketed by different manufacturers. The introduction of a new cuffed endotracheal tube in the market with improved tracheal sealing characteristics may encourage increased safe use of these tubes in clinical practice. A literature search using search words "cuffed endotracheal tube" and "children" from 1980 to January 2012 in PUBMED was conducted. Based on the search, the advantages and potential benefits of cuffed ETT are reviewed in this article. PMID:23492803

  14. Pulse Tube Refrigerator

    NASA Astrophysics Data System (ADS)

    Matsubara, Yoichi

    The pulse tube refrigerator is one of the regenerative cycle refrigerators such as Stirling cycle or Gifford-McMahon cycle which gives the cooling temperature below 150 K down to liquid helium temperature. In 1963, W. E. Gifford invented a simple refrigeration cycle which is composed of compressor, regenerator and simple tube named as pulse tube which gives a similar function of the expander in Stirling or Gifford-McMahon cycle. The thermodynamically performance of this pulse tube refrigerator is inferior to that of other regenerative cycles. In 1984, however, Mikulin and coworkers made a significant advance in pulse tube configuration called as orifice pulse tube. After this, several modifications of the pulse tube hot end configuration have been developed. With those modifications, the thermodynamic performance of the pulse tube refrigerator became the same order to that of Stirling and Gifford-McMahon refrigerator. This article reviews the brief history of the pulse tube refrigerator development in the view point of its thermodynamically efficiency. Simplified theories of the energy flow in the pulse tube have also been described.

  15. EFFECTS OF TOXICANTS ON NEURAL DIFFERENTIATION

    EPA Science Inventory

    This manuscript describes in vitro measures of neural differentiation. This overview provides the background and literature review for measures that could be employed in both screening assays and mechanistic studies. this chapter also reviews data from key endpoints like neurite ...

  16. Neural Networks

    SciTech Connect

    Smith, Patrick I.

    2003-09-23

    Physicists use large detectors to measure particles created in high-energy collisions at particle accelerators. These detectors typically produce signals indicating either where ionization occurs along the path of the particle, or where energy is deposited by the particle. The data produced by these signals is fed into pattern recognition programs to try to identify what particles were produced, and to measure the energy and direction of these particles. Ideally, there are many techniques used in this pattern recognition software. One technique, neural networks, is particularly suitable for identifying what type of particle caused by a set of energy deposits. Neural networks can derive meaning from complicated or imprecise data, extract patterns, and detect trends that are too complex to be noticed by either humans or other computer related processes. To assist in the advancement of this technology, Physicists use a tool kit to experiment with several neural network techniques. The goal of this research is interface a neural network tool kit into Java Analysis Studio (JAS3), an application that allows data to be analyzed from any experiment. As the final result, a physicist will have the ability to train, test, and implement a neural network with the desired output while using JAS3 to analyze the results or output. Before an implementation of a neural network can take place, a firm understanding of what a neural network is and how it works is beneficial. A neural network is an artificial representation of the human brain that tries to simulate the learning process [5]. It is also important to think of the word artificial in that definition as computer programs that use calculations during the learning process. In short, a neural network learns by representative examples. Perhaps the easiest way to describe the way neural networks learn is to explain how the human brain functions. The human brain contains billions of neural cells that are responsible for processing information [2]. Each one of these cells acts as a simple processor. When individual cells interact with one another, the complex abilities of the brain are made possible. In neural networks, the input or data are processed by a propagation function that adds up the values of all the incoming data. The ending value is then compared with a threshold or specific value. The resulting value must exceed the activation function value in order to become output. The activation function is a mathematical function that a neuron uses to produce an output referring to its input value. [8] Figure 1 depicts this process. Neural networks usually have three components an input, a hidden, and an output. These layers create the end result of the neural network. A real world example is a child associating the word dog with a picture. The child says dog and simultaneously looks a picture of a dog. The input is the spoken word ''dog'', the hidden is the brain processing, and the output will be the category of the word dog based on the picture. This illustration describes how a neural network functions.

  17. Conduction cooled tube supports

    DOEpatents

    Worley, Arthur C. (Mt. Tabor, NJ); Becht, IV, Charles (Morristown, NJ)

    1984-01-01

    In boilers, process tubes are suspended by means of support studs that are in thermal contact with and attached to the metal roof casing of the boiler and the upper bend portions of the process tubes. The support studs are sufficiently short that when the boiler is in use, the support studs are cooled by conduction of heat to the process tubes and the roof casing thereby maintaining the temperature of the stud so that it does not exceed 1400.degree. F.

  18. Ruggedized electronographic tube development

    NASA Technical Reports Server (NTRS)

    Nevin, S.

    1981-01-01

    Because of their glass components and lack of far ultraviolet sensitivity, currently available Spectracons are not suited for rocket launch. Technology developed for second generation image tubes and for magnetically focused image tubes can be applied to improve the optical and mechanical properties of these magnetically focused electronographic tubes whose 40 kilovolt signal electrons exit a 4-micrometer thick mica window and penetrate a photographic recording emulsion.

  19. Sapphire tube pressure vessel

    DOEpatents

    Outwater, John O. (Cambridge, MA)

    2000-01-01

    A pressure vessel is provided for observing corrosive fluids at high temperatures and pressures. A transparent Teflon bag contains the corrosive fluid and provides an inert barrier. The Teflon bag is placed within a sapphire tube, which forms a pressure boundary. The tube is received within a pipe including a viewing window. The combination of the Teflon bag, sapphire tube and pipe provides a strong and inert pressure vessel. In an alternative embodiment, tie rods connect together compression fittings at opposite ends of the sapphire tube.

  20. Wound tube heat exchanger

    DOEpatents

    Ecker, Amir L. (Duncanville, TX)

    1983-01-01

    What is disclosed is a wound tube heat exchanger in which a plurality of tubes having flattened areas are held contiguous adjacent flattened areas of tubes by a plurality of windings to give a double walled heat exchanger. The plurality of windings serve as a plurality of effective force vectors holding the conduits contiguous heat conducting walls of another conduit and result in highly efficient heat transfer. The resulting heat exchange bundle is economical and can be coiled into the desired shape. Also disclosed are specific embodiments such as the one in which the tubes are expanded against their windings after being coiled to insure highly efficient heat transfer.

  1. Composite Pulse Tube

    NASA Technical Reports Server (NTRS)

    Martin, Jerry L.; Cloyd, Jason H.

    2007-01-01

    A modification of the design of the pulse tube in a pulse-tube cryocooler reduces axial thermal conductance while preserving radial thermal conductance. It is desirable to minimize axial thermal conductance in the pulse-tube wall to minimize leakage of heat between the warm and cold ends of the pulse tube. At the same time, it is desirable to maximize radial thermal conductance at the cold end of the pulse tube to ensure adequate thermal contact between (1) a heat exchanger in the form of a stack of copper screens inside the pulse tube at the cold end and (2) the remainder of the cold tip, which is the object to which the heat load is applied and from which heat must be removed. The modified design yields a low-heat-leak pulse tube that can be easily integrated with a cold tip. A typical pulse tube of prior design is either a thin-walled metal tube or a metal tube with a nonmetallic lining. It is desirable that the outer surface of a pulse tube be cylindrical (in contradistinction to tapered) to simplify the design of a regenerator that is also part of the cryocooler. Under some conditions, it is desirable to taper the inner surface of the pulse tube to reduce acoustic streaming. The combination of a cylindrical outer surface and a tapered inner surface can lead to unacceptably large axial conduction if the pulse tube is made entirely of metal. Making the pulse-tube wall of a nonmetallic, lowthermal- conductivity material would not solve the problem because the wall would not afford the needed thermal contact for the stack of screens in the cold end. The modified design calls for fabricating the pulse tube in two parts: a longer, nonmetallic part that is tapered on the inside and cylindrical on the outside and a shorter, metallic part that is cylindrical on both the inside and the outside. The nonmetallic part can be made from G-10 fiberglass-reinforced epoxy or other low-thermal-conductivity, cryogenically compatible material. The metallic part must have high thermal conductivity in the cryogenic temperature range and would typically be made of pure copper to satisfy this requirement. The metallic part is bonded to the nonmetallic part with epoxy. Copper screens are inserted in the metallic part to form the cold-end heat exchanger, then the assembled pulse tube is inserted in the cold tip.

  2. Looking Southeast Along Kilauea TEB Tube System

    USGS Multimedia Gallery

    View looking southeast along the fuming trace of the TEB tube system. The growing rootless shield field is in the background just above and to the left of center frame. The low, rounded shape of the shields--especially the shield in shadow to the left--are evident in this photo....

  3. 56. INTERIOR VIEW OF TUBES OF UNCERTAIN USE BELOW THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. INTERIOR VIEW OF TUBES OF UNCERTAIN USE BELOW THE LOWER WEST END OF THE AMALGAMATIONS PLATES. NOTE CUT STONE FOUNDATION WALLS ALONG THE BACKGROUND RIGHT. - Standard Gold Mill, East of Bodie Creek, Northeast of Bodie, Bodie, Mono County, CA

  4. Steam generator tube failures

    SciTech Connect

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

  5. Method for shaping polyethylene tubing

    NASA Technical Reports Server (NTRS)

    Kramer, R. C.

    1981-01-01

    Method forms polyethylene plastic tubing into configurations previously only possible with metal tubing. By using polyethylene in place of copper or stain less steel tubing inlow pressure systems, fabrication costs are significantly reduced. Polyethylene tubing can be used whenever low pressure tubing is needed in oil operations, aircraft and space applications, powerplants, and testing laboratories.

  6. Fallopian Tube Catheterization

    PubMed Central

    Thurmond, Amy Suzanne

    2013-01-01

    Fallopian tube catheterization is used for treatment of infertility caused by proximal tubal occlusion, and has replaced surgical treatment for this condition. More recently, fallopian tube catheterization has been used for tubal sterilization. Interventional radiologists tested numerous methods for tubal occlusion using the rabbit as an animal model. As a result, a tubal device has recently been Food and Drug Administration approved for permanent sterilization using hysteroscopic guidance; it can also be placed fluoroscopically by fallopian tube catheterization as an “off-label” procedure. This is a 5-year continuation and update on a procedure that has been done by interventional radiologists for 25 years; history of the development of fallopian tube catheterization in women has been published in detail in this journal. Highlighted in this article will be description of the basic components needed for fallopian tube catheterization. PMID:24436565

  7. Neural Networks Early Neural Network Modeling

    E-print Network

    Yuste, Rafael

    Appendix E Neural Networks Early Neural Network Modeling Neurons Are Computational Devices A Neuron? This is the central question moti- vating the study of neural networks. In this appendix we provide a brief historical review of the field, intro- duce some key concepts, and discuss two influential models of neural networks

  8. Holder for Straightening Bent Tubes

    NASA Technical Reports Server (NTRS)

    Turner, A. R.; Polzien, E. D.

    1985-01-01

    One-piece holder restrains bent metal tube against further bending during straightening operation. Holder consists of handle 16 in. (41 cm) long welded to short, strong tube that fits around tube to be straightened.

  9. Robotic Tube-Gap Inspector

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Gutow, David A.; Maslakowski, John E.

    1993-01-01

    Robotic vision system measures small gaps between nearly parallel tubes. Robot-held video camera examines closely spaced tubes while computer determines gaps between tubes. Video monitor simultaneously displays data on gaps.

  10. PE on YouTube--Investigating Participation in Physical Education Practice

    ERIC Educational Resources Information Center

    Quennerstedt, Mikael

    2013-01-01

    Background: In this article, students' diverse ways of participating in physical education (PE) practice shown in clips on YouTube were investigated. YouTube is the largest user-generated video-sharing website on the Internet, where different video content is presented. The clips on YouTube, as used in this paper, can be seen as a user-generated…

  11. Modelling flux tube dynamics

    NASA Astrophysics Data System (ADS)

    Dorch, Søren Bertil Fabricius

    2002-10-01

    Over the last few years, numerical models of the behavior of solar magnetic flux tubes have gone from using methods that were essentially one-dimensional (i.e. the thin flux tube approximation), over more or less idealized two-dimensional simulations, to becoming ever more realistic three-dimensional case studies. Along the way a lot of new knowledge has been picked up as to the e.g. the likely topology of the flux tubes, and the instabilities that they are subjected to etc. Within the context of what one could call the "flux tube solar dynamo paradigm," I will discuss recent results of efforts to study buoyant magnetic flux tubes ascending from deep below the photosphere, before they emerge in active regions and interact with the field in the overlying atmosphere (cf. the contributions by Boris Gudiksen and Åke Nordlund): i.e. I am not addressing the flux tubes associated with magnetic bright points, which possibly are generated by a small-scale dynamo operating in the solar photosphere (cf. the contribution by Bob Stein). The presented efforts are numerical MHD simulations of twisted flux ropes and loops, interacting with rotation and convection. Ultimately the magnetic surface signatures of these simulations, when compared to observations, constraints the dynamo processes that are responsible for the generation of the flux ropes in the first place. Along with these new results several questions pop up (both old and new ones), regarding the nature of flux tubes and consequently of the solar dynamo.

  12. Dynamics of tubes in fluid with tube-baffle interaction

    SciTech Connect

    Chen, S.S.; Jendrzejczyk, J.A.; Wambsganss, M.W.

    1983-09-01

    Three series of tests are performed to evaluate the effects of tube to tube-support-plate (TSP) clearance on tube dynamic characteristics and instability phenomena for tube arrays in crossflow. Test results show that, for relatively large clearances, tubes may possess TSP-inactive modes in which the tubes rattle inside some of the tube-support-plate holes, and that the natural frequencies of TSP-inactive modes are lower than those of TSP-active modes, in which the support plates provide knife-edge type support. Tube response characteristics associated with TSP-inactive modes are sensitive to tube-to-TSP clearance, TSP thickness, excitation amplitude, tube alignment, and the fluid inside the clearance. In addition, tube response is intrinsically nonlinear, with the dominance of TSP-inactive or TSP-active modes depending on the magnitudes of different system parameters. In general, such a system is difficult to model; only a full-scale test can provide all the necessary characteristics. A tube array supported by TSPs with relatively large clearances may be subjected to dynamic instability in some of the TSP-inactive modes; tube response characteristics and impact forces on TSPs for a tube row are studied in detail in this report. Tube displacements associated with the instability of a TSP-inactive mode are small; however, impacts of the tube against TSPs may result in significant damage in a relatively short time. 52 figures.

  13. Fallopian Tube Cancer

    MedlinePLUS

    ... Cancer.Net Editorial Board , which is composed of medical, surgical, radiation, gynecologic, and pediatric oncologists, oncology nurses, physician assistants, social workers, and patient advocates. Cancer.Net Guide Fallopian Tube ...

  14. Eustachian Tube Dysfunction

    MedlinePLUS

    ... relieve the “full ear” feeling by taking a deep breath and blowing with your mouth shut and ... effectiveness. For more information, please visit the FDA Web site. Prevention How can I avoid eustachian tube ...

  15. Tubing crimping pliers

    DOEpatents

    Lindholm, G.T.

    1981-02-27

    The disclosure relates to pliers and more particularly to pliers for crimping two or more pieces of copper tubing together prior to their being permanently joined by brazing, soldering or the like. A die containing spring-loaded pins rotates within a cammed ring in the head of the pliers. As the die rotates, the pins force a crimp on tubing held within the pliers.

  16. Dynamic tube/support interaction in heat exchanger tubes

    SciTech Connect

    Chen, S.S.

    1991-01-01

    The supports for heat exchanger tubes are usually plates with drilled holes; other types of supports also have been used. To facilitate manufacture and to allow for thermal expansion of the tubes, small clearances are used between tubes and tube supports. The dynamics of tube/support interaction in heat exchangers is fairly complicated. Understanding tube dynamics and its effects is important for heat exchangers. This paper summarizes the current state of the art on this subject and to identify future research needs. Specifically, the following topics are discussed: dynamics of loosely supported tubes, tube/support gap dynamics, tube response in flow, tube damage and wear, design considerations, and future research needs. 55 refs., 1 fig.

  17. Differentiation state determines neural effects on microvascular endothelial cells

    SciTech Connect

    Muffley, Lara A.; Pan, Shin-Chen; Smith, Andria N.; Ga, Maricar; Hocking, Anne M.; Gibran, Nicole S.

    2012-10-01

    Growing evidence indicates that nerves and capillaries interact paracrinely in uninjured skin and cutaneous wounds. Although mature neurons are the predominant neural cell in the skin, neural progenitor cells have also been detected in uninjured adult skin. The aim of this study was to characterize differential paracrine effects of neural progenitor cells and mature sensory neurons on dermal microvascular endothelial cells. Our results suggest that neural progenitor cells and mature sensory neurons have unique secretory profiles and distinct effects on dermal microvascular endothelial cell proliferation, migration, and nitric oxide production. Neural progenitor cells and dorsal root ganglion neurons secrete different proteins related to angiogenesis. Specific to neural progenitor cells were dipeptidyl peptidase-4, IGFBP-2, pentraxin-3, serpin f1, TIMP-1, TIMP-4 and VEGF. In contrast, endostatin, FGF-1, MCP-1 and thrombospondin-2 were specific to dorsal root ganglion neurons. Microvascular endothelial cell proliferation was inhibited by dorsal root ganglion neurons but unaffected by neural progenitor cells. In contrast, microvascular endothelial cell migration in a scratch wound assay was inhibited by neural progenitor cells and unaffected by dorsal root ganglion neurons. In addition, nitric oxide production by microvascular endothelial cells was increased by dorsal root ganglion neurons but unaffected by neural progenitor cells. -- Highlights: Black-Right-Pointing-Pointer Dorsal root ganglion neurons, not neural progenitor cells, regulate microvascular endothelial cell proliferation. Black-Right-Pointing-Pointer Neural progenitor cells, not dorsal root ganglion neurons, regulate microvascular endothelial cell migration. Black-Right-Pointing-Pointer Neural progenitor cells and dorsal root ganglion neurons do not effect microvascular endothelial tube formation. Black-Right-Pointing-Pointer Dorsal root ganglion neurons, not neural progenitor cells, regulate microvascular endothelial cell production of nitric oxide. Black-Right-Pointing-Pointer Neural progenitor cells and dorsal root ganglion neurons have different secretory profiles for angiogenic mediators.

  18. 3D silicon neural probe with integrated optical fibers for optogenetic modulation.

    PubMed

    Kim, Eric G R; Tu, Hongen; Luo, Hao; Liu, Bin; Bao, Shaowen; Zhang, Jinsheng; Xu, Yong

    2015-07-21

    Optogenetics is a powerful modality for neural modulation that can be useful for a wide array of biomedical studies. Penetrating microelectrode arrays provide a means of recording neural signals with high spatial resolution. It is highly desirable to integrate optics with neural probes to allow for functional study of neural tissue by optogenetics. In this paper, we report the development of a novel 3D neural probe coupled simply and robustly to optical fibers using a hollow parylene tube structure. The device shanks are hollow tubes with rigid silicon tips, allowing the insertion and encasement of optical fibers within the shanks. The position of the fiber tip can be precisely controlled relative to the electrodes on the shank by inherent design features. Preliminary in vivo rat studies indicate that these devices are capable of optogenetic modulation simultaneously with 3D neural signal recording. PMID:26097907

  19. Lava Tubes of Olympus

    NASA Technical Reports Server (NTRS)

    2004-01-01

    5 April 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows evidence of two collapsed lava tubes on the southeast flank of the giant martian volcano, Olympus Mons. One runs diagonally across the entire image, the other is shorter and does not extend across the whole image. The shorter one is a series of pits and troughs, rather than a continuous channel. Lava flowed in tubes under the surface; later, the roof of each tube collapsed to form a series of pits and troughs which, in the larger example, eventually coalesced to its present, channel-like form. The image is located near 16.8oN, 132.2oW, and covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

  20. Advanced evacuated tube collectors

    NASA Astrophysics Data System (ADS)

    Schertz, W. W.; Hull, J. R.; Winston, R.; Ogallagher, J.

    1985-04-01

    The essence of the design concept for these new collectors is the integration of moderate levels of nonimaging concentration inside the evacuated tube itself. This permanently protects the reflection surfaces and allows the use of highly reflecting front surface mirrors with reflectances greater than 95%. Previous fabrication and long term testing of a proof-of-concept prototype has established the technical success of the concept. Present work is directed toward the development of a manufacturable unit that will be suitable for the widest possible range of applications. Design alternatives include scaling up the original prototype's tube diameter from 5 cm to 10 cm, using an internal shaped metal concentrating reflector, using a variety of profile shapes to minimize so-called gap losses and accommodate both single ended and double-ended flow geometries, and allowing the use of heat pipes for the absorber tube.

  1. The electrostatic storage tube

    NASA Technical Reports Server (NTRS)

    Rutherford, R. E., Jr.

    1973-01-01

    An electrostatic camera system is discussed which is based on the electrostatic storage tube. The development of the system was begun following a series of experiments which indicated that the device offers signficantly improved performance over currently available devices. The approach used in developing the high performance camera involves: converting the input image to an electron image at low loss, applying a low noise gain process, and storing the resulting charge pattern in a low-loss target. The basic processes and elements of the electrostatic storage tube are illustrated and discussed. Graphs that depict the camera performance characteristics are included.

  2. On the holographic width of flux tubes

    E-print Network

    Dimitrios Giataganas; Nikos Irges

    2015-02-17

    We investigate the width of the flux tube between heavy static quark charges. Using the gauge/gravity duality, we find the properties of the minimal connected surface related to the width of the bound state. We show that in the confining phase, the logarithmic broadening predicted by the effective string description and observed in lattice simulations is a generic property of all confining backgrounds. We also study the transverse fluctuations of the string connecting two static quarks in curved backgrounds. Our formalism is applied to AdS space where we compute the expectation value of the square of transverse deviations of the string, a quantity related to the width.

  3. Performance of photomultiplier tubes and sodium iodide scintillation detector systems

    NASA Technical Reports Server (NTRS)

    Meegan, C. A.

    1981-01-01

    The performance of photomultiplier tubes (PMT's) and scintillation detector systems incorporating 50.8 by 1.27 cm NaI (T l) crystals was investigated to determine the characteristics of the photomultiplier tubes and optimize the detector geometry for the Burst and Transient Source Experiment on the Gamma Ray Observatory. Background information on performance characteristics of PMT's and NaI (T l) detectors is provided, procedures for measurement of relevant parameters are specified, and results of these measurements are presented.

  4. Tube welding and brazing

    NASA Technical Reports Server (NTRS)

    Poorman, R. M.

    1969-01-01

    Brochures outline the tools, equipment, materials, and techniques used for joining tubes by automatic and semiautomatic welding and brazing. A few of the metals being joined are stainless steels of various diameters and thickness. Techniques have been developed for on-site or work-bench repair.

  5. Shock Tube Design 

    E-print Network

    Koppenberger, Peter K.

    2010-07-14

    was designed. A winch changes the angle of the tube and a telescoping support system maintains the position during experimentation. It was determined after running COSMOS finite element stress analysis, that with the 2.5 MPa internal pressure associated with a...

  6. The Blue Tube.

    ERIC Educational Resources Information Center

    Wallisch, Bill; Taylor, Bob

    The "Blue Tube" is a 2-part academic package developed at the U.S. Air Force Academy consisting of an English course in communication and writing skills and a management course in advertising and marketing; the two courses are interrelated through student assignments in television production. The first part of the package includes training of…

  7. Downhole pulse tube refrigerators

    SciTech Connect

    Swift, G.; Gardner, D.

    1997-12-01

    This report summarizes a preliminary design study to explore the plausibility of using pulse tube refrigeration to cool instruments in a hot down-hole environment. The original motivation was to maintain Dave Reagor`s high-temperature superconducting electronics at 75 K, but the study has evolved to include three target design criteria: cooling at 30 C in a 300 C environment, cooling at 75 K in a 50 C environment, cooling at both 75 K and 30 C in a 250 C environment. These specific temperatures were chosen arbitrarily, as representative of what is possible. The primary goals are low cost, reliability, and small package diameter. Pulse-tube refrigeration is a rapidly growing sub-field of cryogenic refrigeration. The pulse tube refrigerator has recently become the simplest, cheapest, most rugged and reliable low-power cryocooler. The authors expect this technology will be applicable downhole because of the ratio of hot to cold temperatures (in absolute units, such as Kelvin) of interest in deep drilling is comparable to the ratios routinely achieved with cryogenic pulse-tube refrigerators.

  8. Tube Feeding Transition Plateaus

    ERIC Educational Resources Information Center

    Klein, Marsha Dunn

    2007-01-01

    The journey children make from tube feeding to oral feeding is personal for each child and family. There is a sequence of predictable plateaus that children climb as they move toward orally eating. By better understanding this sequence, parents and children can maximize the development, learning, enjoyment and confidence at each plateau. The…

  9. Tube Feeding Troubleshooting Guide

    MedlinePLUS

    ... hours. Formula should not be given at room temperature for more than eight to 12 hours. If you need to run your formula for longer than 12 hours, put ice packs around the formula bag or star t with cold formula. You or the tube ...

  10. Investigation of Pitot tubes

    NASA Technical Reports Server (NTRS)

    Herschel, W H; Buckingham, E

    1917-01-01

    Report describes the principles of operation and characteristics of some of the instruments which have been devised or used to measure both low and high speeds of aeroplanes. Since the pitot tube is the instrument which has been most commonly used in the United States and Great Britain as a speedometer for aeroplanes, it is treated first and somewhat more fully than the others.

  11. Environmental test report for the WX-32335 SEC camera tube. [for International Ultraviolet Explorer

    NASA Technical Reports Server (NTRS)

    Malanoski, R. J.

    1973-01-01

    The environmental testing activity on the WX-32335 was carried out to determine if this tube type could withstand the environmental requirements established for the International Ultraviolet Explorer (IUE) camera tube (WX-32224). The results of the tests led to the following conclusions: (1) The WX-32335 as processed with a CsTe photocathode surface can withstand the temperature extremes established for the IUE camera tube without damage to the photocathode surface or without introducing background signal in the tube after one hour of dark integration. (2) The WX-32335 built with a WX-32224 type target support structure can withstand the sinusoidal vibration requirements established for the IUE camera tube. (3) Although the vibration test of the WX-32335 type tubes built with the flat target ring structure could not be completed, there was no indication that these tubes could not withstand the sinusoidal vibration requirements established for the IUE camera tube.

  12. Statistical Study of Plasma-depleted Flux Tubes in Saturnian Magnetosphere

    NASA Astrophysics Data System (ADS)

    Lai, H. R.; Russell, C. T.; Wei, H. Y.; Dougherty, M. K.; Jia, Y. D.

    2015-10-01

    We have surveyed the occurrence of flux tubes with both enhanced and depressed field strength relative to their surroundings as observed in Cassini magnetometer data. Consistent with earlier studies, enhanced field flux tubes are concentrated near the equator while depressed field flux tubes are distributed in a larger latitudinal region. For both types of flux tubes, their occurrence rates vary with the local time in the same pattern and they contain the same magnetic flux. Therefore, we suggest that those two types of tubes are just different manifestations of the same phenomenon. Near the equator with high ambient plasma density, the flux tubes convecting in from the tail are compressed, resulting in increased field strength. Off the equator,these flux tubes expand slightly, resulting in decreased field strength. The enhanced flux tubes gradually break into smaller ones as they convect inward. Inside an L value of about 5, they become indistinguishable from the background.

  13. Electronic Neural Networks

    NASA Technical Reports Server (NTRS)

    Thakoor, Anil

    1990-01-01

    Viewgraphs on electronic neural networks for space station are presented. Topics covered include: electronic neural networks; electronic implementations; VLSI/thin film hybrid hardware for neurocomputing; computations with analog parallel processing; features of neuroprocessors; applications of neuroprocessors; neural network hardware for terrain trafficability determination; a dedicated processor for path planning; neural network system interface; neural network for robotic control; error backpropagation algorithm for learning; resource allocation matrix; global optimization neuroprocessor; and electrically programmable read only thin-film synaptic array.

  14. Tubing For Sampling Hydrazine Vapor

    NASA Technical Reports Server (NTRS)

    Travis, Josh; Taffe, Patricia S.; Rose-Pehrsson, Susan L.; Wyatt, Jeffrey R.

    1993-01-01

    Report evaluates flexible tubing used for transporting such hypergolic vapors as those of hydrazines for quantitative analysis. Describes experiments in which variety of tubing materials, chosen for their known compatibility with hydrazine, flexibility, and resistance to heat.

  15. Vanadium tube processing and analysis

    SciTech Connect

    Kautz, D.D.; Tanaka, G.J.

    1993-08-11

    Vanadium tubing obtained from Century Tubes, a custom tubing manufacturer, was studied to determine as-received quality and fabricability. Applications for this tubing involve crimping and sealing operations at Pantex Plant requiring very high levels of leak-tightness (leak rates less than 10{sup {minus}8} atm-cc He/sec). The as-received material had poor OD and ID surface finish and cleanliness that needed to be improved before use in component fabrication. Savannah River Technical Center (SRTC) personnel developed a cleaning procedure to make this tubing acceptable for crimping and sealing operations. After suitably cleaning the tubing, we tested several tube sealing techniques and all showed some degree of success. Pantex Plant personnel are now implementing a tube sealing process very similar to one of the techniques studied, a mechanical crimp followed by seal welding.

  16. Ethical Problems of Screening for Neural Tube Defects.

    ERIC Educational Resources Information Center

    Habgood, J. S.

    1978-01-01

    Among the ethical problems in screening for severe spina bifida in a fetus are deciding who should be screened; whether the procedure, which has medical risks, is justified; and how to deal with the only known solution--abortion. Journal availability: see EC 114 865. (PHR)

  17. Are There Disorders or Conditions Associated with Neural Tube Defects?

    MedlinePLUS

    ... the condition—are allergic to latex, or natural rubber. Although researchers still do not entirely understand why ... html [top] Spina Bifida Association. (2008). Latex (natural rubber) allergy in spina bifida. Retrieved March 30, 2012, ...

  18. What Are the Treatments for Neural Tube Defects?

    MedlinePLUS

    ... get around, including braces, crutches, walkers, and wheelchairs. Urinary tract infections; lack of bladder and bowel control. People with ... from completely emptying, a condition that can cause urinary tract infections and kidney damage. Health care providers may address ...

  19. Amphioxus and lamprey AP-2 genes: implications for neural crest evolution and migration patterns

    NASA Technical Reports Server (NTRS)

    Meulemans, Daniel; Bronner-Fraser, Marianne

    2002-01-01

    The neural crest is a uniquely vertebrate cell type present in the most basal vertebrates, but not in cephalochordates. We have studied differences in regulation of the neural crest marker AP-2 across two evolutionary transitions: invertebrate to vertebrate, and agnathan to gnathostome. Isolation and comparison of amphioxus, lamprey and axolotl AP-2 reveals its extensive expansion in the vertebrate dorsal neural tube and pharyngeal arches, implying co-option of AP-2 genes by neural crest cells early in vertebrate evolution. Expression in non-neural ectoderm is a conserved feature in amphioxus and vertebrates, suggesting an ancient role for AP-2 genes in this tissue. There is also common expression in subsets of ventrolateral neurons in the anterior neural tube, consistent with a primitive role in brain development. Comparison of AP-2 expression in axolotl and lamprey suggests an elaboration of cranial neural crest patterning in gnathostomes. However, migration of AP-2-expressing neural crest cells medial to the pharyngeal arch mesoderm appears to be a primitive feature retained in all vertebrates. Because AP-2 has essential roles in cranial neural crest differentiation and proliferation, the co-option of AP-2 by neural crest cells in the vertebrate lineage was a potentially crucial event in vertebrate evolution.

  20. 78 FR 48416 - Light-Walled Rectangular Pipe and Tube From the People's Republic of China: Final Results of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-08

    ...Trade Administration [C-570-915] Light-Walled Rectangular Pipe and Tube From...review of the countervailing duty order on light-walled rectangular pipe and tube from...Background The countervailing duty order on light-walled rectangular pipe and tube...

  1. Neural crest: The fourth germ layer

    PubMed Central

    Shyamala, K; Yanduri, Sarita; Girish, HC; Murgod, Sanjay

    2015-01-01

    The neural crest cells (NCCs), a transient group of cells that emerges from the dorsal aspect of the neural tube during early vertebrate development has been a fascinating group of cells because of its multipotency, long range migration through embryo and its capacity to generate a prodigious number of differentiated cell types. For these reasons, although derived from the ectoderm, the neural crest (NC) has been called the fourth germ layer. The non neural ectoderm, the neural plate and the underlying mesoderm are needed for the induction and formation of NC cells. Once formed, NC cells start migrating as a wave of cells, moving away from the neuroepithelium and quickly splitting into distinct streams. These migrating NCCs home in to different regions and give rise to plethora of tissues. Umpteen number of signaling molecules are essential for formation, epithelial mesenchymal transition, delamination, migration and localization of NCC. Authors believe that a clear understanding of steps and signals involved in NC formation, migration, etc., may help in understanding the pathogenesis behind cancer metastasis and many other diseases. Hence, we have taken this review to discuss the various aspects of the NC cells. PMID:26604500

  2. Enteral Tube Feeding and Pneumonia

    ERIC Educational Resources Information Center

    Gray, David Sheridan; Kimmel, David

    2006-01-01

    To determine the effects of enteral tube feeding on the incidence of pneumonia, we performed a retrospective review of all clients at our institution who had gastrostomy or jejunostomy tubes placed over a 10-year period. Ninety-three subjects had a history of pneumonia before feeding tube insertion. Eighty had gastrostomy and 13, jejunostomy…

  3. Composite Cathode-Ray Tube

    NASA Technical Reports Server (NTRS)

    Gangal, Mukund D.

    1988-01-01

    Proposed composite cathode-ray tube consists of rectangular array of cathode-ray tubes joined at edges, sharing common vacuum. Each electron gun generates independent image on portion of screen. Composite tube operates most advantageously under digital control to make available several display modes. Brightness and resolution of large images increased. Useful for classroom presentations, conferences, and the like.

  4. Carving: Scalable Interactive Segmentation of Neural Volume Electron Microscopy Images

    E-print Network

    Hamprecht, Fred A.

    Carving: Scalable Interactive Segmentation of Neural Volume Electron Microscopy Images C. N electron microscopy images. We propose a supervoxel-based en- ergy function with a novel background prior available. Keywords: electron microscopy, seeded segmentation, interactive seg- mentation, graph cut

  5. Tube coupling device

    NASA Technical Reports Server (NTRS)

    Myers, William N. (inventor); Hein, Leopold A. (inventor)

    1987-01-01

    A first annular ring of a tube coupling device has a keyed opening sized to fit around the nut region of a male coupling, and a second annular ring has a keyed opening sized to fit around the nut of a female coupling. Each ring has mating ratchet teeth and these rings are biased together, thereby engaging these teeth and preventing rotation of these rings. This in turn prevents the rotation of the male nut region with respect to the female nut. For tube-to-bulkhead locking, one facet of one ring is notched, and a pin is pressed into an opening in the bulkhead. This pin is sized to fit within one of the notches in the ring, thereby preventing rotation of this ring with respect to the bulkhead.

  6. YouTube Physics

    NASA Astrophysics Data System (ADS)

    Riendeau, Diane

    2012-09-01

    To date, this column has presented videos to show in class, Don Mathieson from Tulsa Community College suggested that YouTube could be used in another fashion. In Don's experience, his students are not always prepared for the mathematic rigor of his course. Even at the high school level, math can be a barrier for physics students. Walid Shihabi, a colleague of Don's, decided to compile a list of YouTube videos that his students could watch to relearn basic mathematics. I thought this sounded like a fantastic idea and a great service to the students. Walid graciously agreed to share his list and I have reproduced a large portion of it below.

  7. Induction plasma tube

    DOEpatents

    Hull, D.E.

    1982-07-02

    An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

  8. Induction plasma tube

    DOEpatents

    Hull, Donald E. (Los Alamos, NM)

    1984-01-01

    An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

  9. Machine Learning ! ! ! ! !Srihari Neural Networks!

    E-print Network

    Machine Learning ! ! ! ! !Srihari 1 Neural Networks! #12;Machine Learning ! ! ! ! !Srihari 2 Two ! ! ! ! !Srihari 3 Neural Computation! Biological Motivation for Artificial Neural Networks #12;Machine Learning Groups Of Researchers in Neural Networks! 1. Study and model biological learning! · Network of neurons

  10. Joined concentric tubes

    SciTech Connect

    DeJonghe, Lutgard; Jacobson, Craig; Tucker, Michael; Visco, Steven

    2013-01-01

    Tubular objects having two or more concentric layers that have different properties are joined to one another during their manufacture primarily by compressive and friction forces generated by shrinkage during sintering and possibly mechanical interlocking. It is not necessary for the concentric tubes to display adhesive-, chemical- or sinter-bonding to each other in order to achieve a strong bond. This facilitates joining of dissimilar materials, such as ceramics and metals.

  11. Traveling-Wave Tubes

    NASA Technical Reports Server (NTRS)

    Kory, Carol L.

    1998-01-01

    The traveling-wave tube (TWT) is a vacuum device invented in the early 1940's used for amplification at microwave frequencies. Amplification is attained by surrendering kinetic energy from an electron beam to a radio frequency (RF) electromagnetic wave. The demand for vacuum devices has been decreased largely by the advent of solid-state devices. However, although solid state devices have replaced vacuum devices in many areas, there are still many applications such as radar, electronic countermeasures and satellite communications, that require operating characteristics such as high power (Watts to Megawatts), high frequency (below 1 GHz to over 100 GHz) and large bandwidth that only vacuum devices can provide. Vacuum devices are also deemed irreplaceable in the music industry where musicians treasure their tube-based amplifiers claiming that the solid-state and digital counterparts could never provide the same "warmth" (3). The term traveling-wave tube includes both fast-wave and slow-wave devices. This article will concentrate on slow-wave devices as the vast majority of TWTs in operation fall into this category.

  12. Concentric tube support assembly

    DOEpatents

    Rubio, Mark F.; Glessner, John C.

    2012-09-04

    An assembly (45) includes a plurality of separate pie-shaped segments (72) forming a disk (70) around a central region (48) for retaining a plurality of tubes (46) in a concentrically spaced apart configuration. Each segment includes a support member (94) radially extending along an upstream face (96) of the segment and a plurality of annularly curved support arms (98) transversely attached to the support member and radially spaced apart from one another away from the central region for receiving respective upstream end portions of the tubes in arc-shaped spaces (100) between the arms. Each segment also includes a radial passageway (102) formed in the support member for receiving a fluid segment portion (106) and a plurality of annular passageways (104) formed in the support arms for receiving respective arm portions (108) of the fluid segment portion from the radial passageway and for conducting the respective arm portions into corresponding annular spaces (47) formed between the tubes retained by the disk.

  13. Tubular Solutions of Dirac-Born-Infeld Action on Dp-Brane Background

    E-print Network

    Wung-Hong Huang

    2005-01-02

    We use the Dirac-Born-Infeld action on Dp-brane background to find the tubular bound state of a D2 with $m$ D0-branes and $n$ fundamental strings. The fundamental strings may be the circular strings along the cross section of tube or the straight strings along the axial of the tube, and tube solutions are parallel to the geometry of Dp-brane background. Through the detailed analyses we show that only on the D6-brane background could we find the stable tubular solutions. These tubular configurations are prevented form collapse by the gravitational field on the curved Dp-brane background.

  14. Elastocapillary flows in flexible tubes

    NASA Astrophysics Data System (ADS)

    Hoberg, Theresa B.; Verneuil, Emilie; Hosoi, A. E.

    2014-12-01

    Interactions between capillary and elastic effects are relevant to a variety of applications from micro- and nano-scale manufacturing to biological systems. In this work, we investigate capillary flows in flexible, millimeter-scale cylindrical elastic tubes. We demonstrate that surface tension can cause sufficiently flexible tubes to collapse and coalesce spontaneously through non-axisymmetric buckling, and develop criteria for the initial deformation and complete collapse of a circular tube. Experimental results for capillary rise and evaporation of a liquid in a flexible tube are presented, and several regimes are seen for the equilibrium state of a flexible tube deforming under capillary pressure. Deformations of the tube walls are measured in different regimes and compared with a shell theory model. Analysis and experimental results show that despite the complex and non-axisymmetric deformed shapes of cylindrical structures, the elastocapillary length used in previous literature for flat plates and sheets can be used to predict the behavior of flexible tubes.

  15. Hybrid endotracheal tubes

    NASA Astrophysics Data System (ADS)

    Sakezles, Christopher Thomas

    Intubation involves the placement of a tube into the tracheal lumen and is prescribed in any setting in which the airway must be stabilized or the patient anesthetized. The purpose of the endotracheal tube in these procedures is to maintain a viable airway, facilitate mechanical ventilation, allow the administration of anesthetics, and prevent the reflux of vomitus into the lungs. In order to satisfy these requirements a nearly airtight seal must be maintained between the tube and the tracheal lining. Most conventional endotracheal tubes provide this seal by employing a cuff that is inflated once the tube is in place. However, the design of this cuff and properties of the material are a source of irritation and injury to the tracheal tissues. In fact, the complication rate for endotracheal intubation is reported to be between 10 and 60%, with manifestations ranging from severe sore throat to erosion through the tracheal wall. These complications are caused by a combination of the materials employed and the forces exerted by the cuff on the tracheal tissues. In particular, the abrasive action of the cuff shears cells from the lining, epithelium adhering to the cuff is removed during extubation, and normal forces exerted on the basement tissues disrupt the blood supply and cause pressure necrosis. The complications associated with tracheal intubation may be reduced or eliminated by employing airway devices constructed from hydrogel materials. Hydrogels are a class of crosslinked polymers which swell in the presence of moisture, and may contain more than 95% water by weight. For the current study, several prototype airway devices were constructed from hydrogel materials including poly(vinyl alcohol), poly(hydroxyethyl methacrylate), and poly(vinyl pyrrolidone). The raw hydrogel materials from this group were subjected to tensile, swelling, and biocompatibility testing, while the finished devices were subjected to extensive mechanical simulation and animal trials. During the course of these experiments it was discovered that reduced water content hydrogel materials generally exhibited superior mechanical properties, but performed more poorly during simulation and biocompatibility studies. Conversely, higher water content materials exhibited lower mechanical performance but superior simulation and biocompatibility results.

  16. Liquid-Nitrogen Test for Blocked Tubes

    NASA Technical Reports Server (NTRS)

    Wagner, W. R.

    1984-01-01

    Nondestructive test identifies obstructed tube in array of parallel tubes. Trickle of liquid nitrogen allowed to flow through tube array until array accumulates substantial formation of frost from moisture in air. Flow stopped and warm air introduced into inlet manifold to heat tubes in array. Tubes still frosted after others defrosted identified as obstructed tubes. Applications include inspection of flow systems having parallel legs.

  17. Neural Filters for Jet Analysis

    E-print Network

    Dawei W Dong; Miklos Gyulassy

    1993-05-09

    We study the efficiency of a neural-net filter and deconvolution method for estimating jet energies and spectra in high-background reactions such as nuclear collisions at the relativistic heavy-ion collider and the large hadron collider. The optimal network is shown to be surprisingly close but not identical to a linear high-pass filter. A suitably constrained deconvolution method is shown to uncover accurately the underlying jet distribution in spite of the broad network response. Finally, we show that possible changes of the jet spectrum in nuclear collisions can be analyzed quantitatively, in terms of an effective energy loss with the proposed method. {} {Dong D W and Gyulassy M 1993}{Neural filters for jet analysis} {(LBL-31560) Physical Review E Vol~47(4) pp~2913-2922}

  18. Using Neural Networks 

    E-print Network

    Gabel, S.

    2003-01-01

    A neural network approach is employed for estimating key efficiency parameters in a gas turbine engine. The concept is demonstrated within a limited operating region for a given engine. The neural network is developed to estimate certain...

  19. Optical Neural Interfaces

    PubMed Central

    Warden, Melissa R.; Cardin, Jessica A.; Deisseroth, Karl

    2014-01-01

    Genetically encoded optical actuators and indicators have changed the landscape of neuroscience, enabling targetable control and readout of specific components of intact neural circuits in behaving animals. Here, we review the development of optical neural interfaces, focusing on hardware designed for optical control of neural activity, integrated optical control and electrical readout, and optical readout of population and single-cell neural activity in freely moving mammals. PMID:25014785

  20. Lava Tube Collapse Pits

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    We will be looking at collapse pits for the next two weeks. Collapse pits on Mars are formed in several ways. In volcanic areas, channelized lava flows can form roofs which insulate the flowing lava. These features are termed lava tubes on Earth and are common features in basaltic flows. After the lava has drained, parts of the roof of the tube will collapse under its own weight. These collapse pits will only be as deep as the bottom of the original lava tube. Another type of collapse feature associated with volcanic areas arises when very large eruptions completely evacuate the magma chamber beneath the volcano. The weight of the volcano will cause the entire edifice to subside into the void space below it. Structural features including fractures and graben will form during the subsidence. Many times collapse pits will form within the graben. In addition to volcanic collapse pits, Mars has many collapse pits formed when volatiles (such as subsurface ice) are released from the surface layers. As the volatiles leave, the weight of the surrounding rock causes collapse pits to form.

    These collapse pits are found in the southern hemisphere of Mars. They are likely lava tube collapse pits related to flows from Hadriaca Patera.

    Image information: VIS instrument. Latitude -36.8, Longitude 89.6 East (270.4 West). 19 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  1. Diffusion in a Curved Tube

    E-print Network

    Naohisa Ogawa

    2013-03-01

    The diffusion of particles in confining walls forming a tube is discussed. Such a transport phenomenon is observed in biological cells and porous media. We consider the case in which the tube is winding with curvature and torsion, and the thickness of the tube is sufficiently small compared with its curvature radius. We discuss how geomerical quantities appear in a quasi-one-dimensional diffusion equation.

  2. Tubing for augmented heat transfer

    SciTech Connect

    Yampolsky, J.S.; Pavlics, P.

    1983-08-01

    The objectives of the program reported were: to determine the heat transfer and friction characteristics on the outside of spiral fluted tubing in single phase flow of water, and to assess the relative cost of a heat exchanger constructed with spiral fluted tubing with one using conventional smooth tubing. An application is examined where an isolation water/water heat exchanger was used to transfer the heat from a gaseous diffusion plant to an external system for energy recovery. (LEW)

  3. Free compression tube. Applications

    NASA Astrophysics Data System (ADS)

    Rusu, Ioan

    2012-11-01

    During the flight of vehicles, their propulsion energy must overcome gravity, to ensure the displacement of air masses on vehicle trajectory, to cover both energy losses from the friction between a solid surface and the air and also the kinetic energy of reflected air masses due to the impact with the flying vehicle. The flight optimization by increasing speed and reducing fuel consumption has directed research in the aerodynamics field. The flying vehicles shapes obtained through studies in the wind tunnel provide the optimization of the impact with the air masses and the airflow along the vehicle. By energy balance studies for vehicles in flight, the author Ioan Rusu directed his research in reducing the energy lost at vehicle impact with air masses. In this respect as compared to classical solutions for building flight vehicles aerodynamic surfaces which reduce the impact and friction with air masses, Ioan Rusu has invented a device which he named free compression tube for rockets, registered with the State Office for Inventions and Trademarks of Romania, OSIM, deposit f 2011 0352. Mounted in front of flight vehicles it eliminates significantly the impact and friction of air masses with the vehicle solid. The air masses come into contact with the air inside the free compression tube and the air-solid friction is eliminated and replaced by air to air friction.

  4. Learning from YouTube [Video Book

    ERIC Educational Resources Information Center

    Juhasz, Alexandra

    2011-01-01

    YouTube is a mess. YouTube is for amateurs. YouTube dissolves the real. YouTube is host to inconceivable combos. YouTube is best for corporate-made community. YouTube is badly baked. These are a few of the things Media Studies professor Alexandra Juhasz (and her class) learned about YouTube when she set out to investigate what actually happens…

  5. Reduced-vibration tube array

    DOEpatents

    Bruck, Gerald J.; Bartolomeo, Daniel R.

    2004-07-20

    A reduced-vibration tube array is disclosed. The array includes a plurality of tubes in a fixed arrangement and a plurality of damping members positioned within the tubes. The damping members include contoured interface regions characterized by bracing points that selectively contact the inner surface of an associated tube. Each interface region is sized and shaped in accordance with the associated tube, so that the damping member bracing points are spaced apart a vibration-reducing distance from the associated tube inner surfaces at equilibrium. During operation, mechanical interaction between the bracing points and the tube inner surfaces reduces vibration by a damage-reducing degree. In one embodiment, the interface regions are serpentine shaped. In another embodiment, the interface regions are helical in shape. The interface regions may be simultaneously helical and serpentine in shape. The damping members may be fixed within the associated tubes, and damping member may be customized several interference regions having attributes chosen in accordance with desired flow characteristics and associated tube properties.

  6. Circular Scan Streak Tube Development

    NASA Technical Reports Server (NTRS)

    Nevin, S.

    1980-01-01

    A streak tube having circular scan was designed, built and tested. Continuous circular scan, easily derived from out of phase sine waves applied to the conventional deflection plates, permits the timing of pulses traveling long baselines. At the tube's output a circular array of 720 elements is scanned to provide 30 to 40 picosecond resolution. Initial difficulties with electron bombarded silicon arrays were circumvented by using microchannel plates within the streak tube to provide the needed electronic amplification and digital sensitivity and coupling the 720 element arrays to the electron beam by means of a phosphor on a fiber optics. Two ceramic body tubes with S-20 photocathodes were tested and delivered.

  7. Electron tubes for industrial applications

    NASA Astrophysics Data System (ADS)

    Gellert, Bernd

    1994-05-01

    This report reviews research and development efforts within the last years for vacuum electron tubes, in particular power grid tubes for industrial applications. Physical and chemical effects are discussed that determine the performance of todays devices. Due to the progress made in the fundamental understanding of materials and newly developed processes the reliability and reproducibility of power grid tubes could be improved considerably. Modern computer controlled manufacturing methods ensure a high reproducibility of production and continuous quality certification according to ISO 9001 guarantees future high quality standards. Some typical applications of these tubes are given as an example.

  8. Method for producing a tube

    DOEpatents

    Peterson, Kenneth A. (Albuquerque, NM); Rohde, Steven B. (Corrales, NM); Pfeifer, Kent B. (Los Lunas, NM); Turner, Timothy S. (Rio Rancho, NM)

    2007-01-02

    A method is described for producing tubular substrates having parallel spaced concentric rings of electrical conductors that can be used as the drift tube of an Ion Mobility Spectrometer (IMS). The invention comprises providing electrodes on the inside of a tube that are electrically connected to the outside of the tube through conductors that extend between adjacent plies of substrate that are combined to form the tube. Tubular substrates are formed from flexible polymeric printed wiring board materials, ceramic materials and material compositions of glass and ceramic, commonly known as Low Temperature Co-Fired Ceramic (LTCC). The adjacent plies are sealed together around the electrode.

  9. Foundations of neural networks

    SciTech Connect

    Simpson, P.K.

    1994-12-31

    Building intelligent systems that can model human behavior has captured the attention of the world for years. So, it is not surprising that a technology such as neural networks has generated great interest. This paper will provide an evolutionary introduction to neural networks by beginning with the key elements and terminology of neural networks, and developing the topologies, learning laws, and recall dynamics from this infrastructure. The perspective taken in this paper is largely that of an engineer, emphasizing the application potential of neural networks and drawing comparisons with other techniques that have similar motivations. As such, mathematics will be relied upon in many of the discussions to make points as precise as possible. The paper begins with a review of what neural networks are and why they are so appealing. A typical neural network is immediately introduced to illustrate several of the key features. With this network as a reference, the evolutionary introduction to neural networks is then pursued. The fundamental elements of a neural network, such as input and output patterns, processing element, connections, and threshold operations, are described, followed by descriptions of neural network topologies, learning algorithms, and recall dynamics. A taxonomy of neural networks is presented that uses two of the key characteristics of learning and recall. Finally, a comparison of neural networks and similar nonneural information processing methods is presented.

  10. Effect of the sequence of tube rolling in a tube bundle of a shell and tube heat exchanger on the stress-deformed state of the tube sheet

    NASA Astrophysics Data System (ADS)

    Tselishchev, M. F.; Plotnikov, P. N.; Brodov, Yu. M.

    2015-11-01

    Rolling the tube sheet of a heat exchanger with U-shaped tubes, as exemplified by the vapor cooler GP-24, was simulated. The simulation was performed using the finite element method with account of elas- tic-plastic properties of the tube and tube sheet materials. The simulation consisted of two stages; at the first stage, maximum and residual contact stress in the conjunction of a separate tube and the tube sheet was determined using the "equivalent sleeve" model; at the second stage, the obtained contact stress was applied to the hole surface in the tube sheet. Thus, different tube rolling sequences were simulated: from the center to the periphery of the tube sheet and from the periphery to the center along a spiral line. The studies showed that the tube rolling sequence noticeably influences the value of the tube sheet residual deflection for the same rolling parameters of separate tubes. Residual deflection of the tube sheet in different planes was determined. It was established that the smallest residual deflection corresponds to the tube rolling sequence from the periphery to the center of the tube sheet. The following dependences were obtained for different rolling sequences: maximum deformation of the tube sheet as a function of the number of rolled tubes, residual deformation of the tube sheet along its surface, and residual deflection of the tube sheet as a function of the rotation angle at the periphery. The preferred sequence of tube rolling for minimizing the tube sheet deformation is indicated.

  11. The LILARTI neural network system

    SciTech Connect

    Allen, J.D. Jr.; Schell, F.M.; Dodd, C.V.

    1992-10-01

    The material of this Technical Memorandum is intended to provide the reader with conceptual and technical background information on the LILARTI neural network system of detail sufficient to confer an understanding of the LILARTI method as it is presently allied and to facilitate application of the method to problems beyond the scope of this document. Of particular importance in this regard are the descriptive sections and the Appendices which include operating instructions, partial listings of program output and data files, and network construction information.

  12. Migratory neuronal progenitors arise from the neural plate borders in tunicates.

    PubMed

    Stolfi, Alberto; Ryan, Kerrianne; Meinertzhagen, Ian A; Christiaen, Lionel

    2015-11-19

    The neural crest is an evolutionary novelty that fostered the emergence of vertebrate anatomical innovations such as the cranium and jaws. During embryonic development, multipotent neural crest cells are specified at the lateral borders of the neural plate before delaminating, migrating and differentiating into various cell types. In invertebrate chordates (cephalochordates and tunicates), neural plate border cells express conserved factors such as Msx, Snail and Pax3/7 and generate melanin-containing pigment cells, a derivative of the neural crest in vertebrates. However, invertebrate neural plate border cells have not been shown to generate homologues of other neural crest derivatives. Thus, proposed models of neural crest evolution postulate vertebrate-specific elaborations on an ancestral neural plate border program, through acquisition of migratory capabilities and the potential to generate several cell types. Here we show that a particular neuronal cell type in the tadpole larva of the tunicate Ciona intestinalis, the bipolar tail neuron, shares a set of features with neural-crest-derived spinal ganglia neurons in vertebrates. Bipolar tail neuron precursors derive from caudal neural plate border cells, delaminate and migrate along the paraxial mesoderm on either side of the neural tube, eventually differentiating into afferent neurons that form synaptic contacts with both epidermal sensory cells and motor neurons. We propose that the neural plate borders of the chordate ancestor already produced migratory peripheral neurons and pigment cells, and that the neural crest evolved through the acquisition of a multipotent progenitor regulatory state upstream of multiple, pre-existing neural plate border cell differentiation programs. PMID:26524532

  13. Traveling wave tube circuit

    NASA Technical Reports Server (NTRS)

    Connolly, D. J. (inventor)

    1978-01-01

    A traveling wave tube (TWT) has a slow wave structure (SWS) which is severed into two or more sections. A signal path, connects the end of an SWS section to the beginning of the following SWS section. The signal path comprises an impedance matching coupler (IMC), followed by an isolator, a variable phase shifter, and a second IMC. The aggregate band pass characteristic of the components in the signal path is chosen to reject, or strongly attenuate, all frequencies outside the desired operating frequency range of the TWT and yet pass, with minimal attenuation in the forward direction, all frequencies within the desired operating frequency range. The isolator is chosen to reject, or strongly attenuate, waves, of all frequencies, which propagate in the backward direction. The aggregate phase shift characteristic of the components in the signal path is chosen to apply signal power to the beginning of the following SWS section with the phase angle yielding maximum efficiency.

  14. Optically powered photomultiplier tube

    NASA Astrophysics Data System (ADS)

    Flesner, Larry D.; Miller, Stephen A.; Dubbelday, Wadad B.

    1993-03-01

    An optically powered photomultiplier tube is provided, comprising a vacuum chamber having a window for incident optical radiation which is to be detected. Also described are a photocathode to receive the optical radiation; an electron multiplier system within the chamber to amplify the electron current from the photocathode; an anode to receive the amplified electron current; a high voltage photocell array positioned within the chamber for generating high voltage electrical power that is provided to the electron multiplier system; a system for delivering optical power to the photocell array; a first electrical contact penetrating the container in a vacuum tight manner and operably coupled to the anode; and a second electrical contact penetrating the container in a vacuum tight manner and operably coupled to the photocell array.

  15. Piezoelectric Rotary Tube Motor

    NASA Technical Reports Server (NTRS)

    Fisher, Charles D.; Badescu, Mircea; Braun, David F.; Culhane, Robert

    2011-01-01

    A custom rotary SQUIGGLE(Registered TradeMark) motor has been developed that sets new benchmarks for small motor size, high position resolution, and high torque without gear reduction. Its capabilities cannot be achieved with conventional electromagnetic motors. It consists of piezoelectric plates mounted on a square flexible tube. The plates are actuated via voltage waveforms 90 out of phase at the resonant frequency of the device to create rotary motion. The motors were incorporated into a two-axis postioner that was designed for fiber-fed spectroscopy for ground-based and space-based projects. The positioner enables large-scale celestial object surveys to take place in a practical amount of time.

  16. Building Background Knowledge

    ERIC Educational Resources Information Center

    Neuman, Susan B.; Kaefer, Tanya; Pinkham, Ashley

    2014-01-01

    This article make a case for the importance of background knowledge in children's comprehension. It suggests that differences in background knowledge may account for differences in understanding text for low- and middle-income children. It then describes strategies for building background knowledge in the age of common core standards.

  17. mixing tube vent to vacuum

    E-print Network

    Wilson, Rachel

    mixing tube vent to vacuum main air tube (ID = 6 mm) valve (Cole Palmer 01380-02) a 0 10 20 30 40 after placing an odor into the device vacuum line. (c) Command to the valve, created from binary random

  18. 2014 Tube -1 STANDING WAVES

    E-print Network

    Gustafsson, Torgny

    2014 Tube - 1 STANDING WAVES IN AN AIR COLUMN The objective of the experiment is: · To study the harmonic structure of standing waves in an air column. APPARATUS: Computer, FFTScope software, PC speaker, meterstick, sound tube apparatus, thermometer, microphone INTRODUCTION traveling wave of sinusoidal shape

  19. Tubes at Glen Canyon Dam

    USGS Multimedia Gallery

    The river outlet tubes at Glen Canyon Dam on the Colorado River in Arizona. At noon Monday, Nov. 19, U.S. Interior Secretary Ken Salazar will open the dam's river outlet tubes, releasing controlled flows larger than the usual 8,000-25,000 cubic feet per second that flows through the turbines of...

  20. Id expression in amphioxus and lamprey highlights the role of gene cooption during neural crest evolution

    NASA Technical Reports Server (NTRS)

    Meulemans, Daniel; McCauley, David; Bronner-Fraser, Marianne

    2003-01-01

    Neural crest cells are unique to vertebrates and generate many of the adult structures that differentiate them from their closest invertebrate relatives, the cephalochordates. Id genes are robust markers of neural crest cells at all stages of development. We compared Id gene expression in amphioxus and lamprey to ask if cephalochordates deploy Id genes at the neural plate border and dorsal neural tube in a manner similar to vertebrates. Furthermore, we examined whether Id expression in these cells is a basal vertebrate trait or a derived feature of gnathostomes. We found that while expression of Id genes in the mesoderm and endoderm is conserved between amphioxus and vertebrates, expression in the lateral neural plate border and dorsal neural tube is a vertebrate novelty. Furthermore, expression of lamprey Id implies that recruitment of Id genes to these cells occurred very early in the vertebrate lineage. Based on expression in amphioxus we postulate that Id cooption conferred sensory cell progenitor-like properties upon the lateral neurectoderm, and pharyngeal mesoderm-like properties upon cranial neural crest. Amphioxus Id expression is also consistent with homology between the anterior neurectoderm of amphioxus and the presumptive placodal ectoderm of vertebrates. These observations support the idea that neural crest evolution was driven in large part by cooption of multipurpose transcriptional regulators from other tissues and cell types.

  1. Evolvable Neural Software System

    NASA Technical Reports Server (NTRS)

    Curtis, Steven A.

    2009-01-01

    The Evolvable Neural Software System (ENSS) is composed of sets of Neural Basis Functions (NBFs), which can be totally autonomously created and removed according to the changing needs and requirements of the software system. The resulting structure is both hierarchical and self-similar in that a given set of NBFs may have a ruler NBF, which in turn communicates with other sets of NBFs. These sets of NBFs may function as nodes to a ruler node, which are also NBF constructs. In this manner, the synthetic neural system can exhibit the complexity, three-dimensional connectivity, and adaptability of biological neural systems. An added advantage of ENSS over a natural neural system is its ability to modify its core genetic code in response to environmental changes as reflected in needs and requirements. The neural system is fully adaptive and evolvable and is trainable before release. It continues to rewire itself while on the job. The NBF is a unique, bilevel intelligence neural system composed of a higher-level heuristic neural system (HNS) and a lower-level, autonomic neural system (ANS). Taken together, the HNS and the ANS give each NBF the complete capabilities of a biological neural system to match sensory inputs to actions. Another feature of the NBF is the Evolvable Neural Interface (ENI), which links the HNS and ANS. The ENI solves the interface problem between these two systems by actively adapting and evolving from a primitive initial state (a Neural Thread) to a complicated, operational ENI and successfully adapting to a training sequence of sensory input. This simulates the adaptation of a biological neural system in a developmental phase. Within the greater multi-NBF and multi-node ENSS, self-similar ENI s provide the basis for inter-NBF and inter-node connectivity.

  2. Characterization of domestic and foreign image intensifier tubes

    NASA Astrophysics Data System (ADS)

    Bender, Edward J.; Wood, Michael V.; Hosek, Daniel J.; Hart, Steve D.

    2013-06-01

    The market for military-use Generation 2 and Generation 3 image intensifier (I2) tubes has become truly global, with major manufacturers and customers spanning five continents. This worldwide market is becoming increasingly important to U.S. manufacturers, with the majority of U.S. Army intensifier fielding having been completed in 2012. Given this keen global competition, it is not surprising that the advertised tube performance of a given source is often discounted by competitors, and the customers have no objective "honest broker" to determine the relative accuracy of these claims. To help fill this void, the U.S. Army RDECOM CERDEC NVESD recently measured a number of domestic and foreign image intensifier tubes, using consistent test equipment/procedures with which the U.S. industry must correlate for Army tube deliveries. Data and analysis will be presented for the major tube parameters of luminance gain, equivalent background input (EBI), signal-to-noise ratio (SNR), limiting resolution, halo, and modulation transfer function (MTF). The bright-light resolution provided by various auto-gated and non-gated tubes will also be addressed, since this area has been an important factor in the international market. RDECOM CERDEC NVESD measurement data will be compared to the corresponding manufacturer specifications whenever possible.

  3. Eddy current signal comparison for tube identification

    NASA Astrophysics Data System (ADS)

    Glass, S. W.; Vojvodic, R.

    2015-03-01

    Inspection of nuclear power plant steam generator tubes is required to justify continued safe plant operation. The steam generators consist of thousands of tubes with nominal diameters of 15 to 22mm, approximately 1mm wall thickness, and 20 to 30m in length. The tubes are inspected by passing an eddy current probe through the tubes from tube end to tube end. It is critical to know exactly which tube identification (row and column) is associated with each tube's data. This is controlled by a precision manipulator that provides the tube ID to the eddy current system. Historically there have been some instances where the manipulator incorrectly reported the tube ID. This can have serious consequences including lack of inspection of a tube, or if a pluggable indication is detected, the tube is likely to be mis-plugged thereby risking a primary to secondary leak.

  4. Water-storage-tube systems. Final report

    SciTech Connect

    Hemker, P.

    1981-12-24

    Passive solar collection/storage/distribution systems were surveyed, designed, fabricated, and mechanically and thermally tested. The types studied were clear and opaque fiberglass tubes, metal tubes with plastic liners, and thermosyphoning tubes. (MHR)

  5. Eddy current signal comparison for tube identification

    SciTech Connect

    Glass, S. W. E-mail: Ratko.Vojvodic@areva.com; Vojvodic, R. E-mail: Ratko.Vojvodic@areva.com

    2015-03-31

    Inspection of nuclear power plant steam generator tubes is required to justify continued safe plant operation. The steam generators consist of thousands of tubes with nominal diameters of 15 to 22mm, approximately 1mm wall thickness, and 20 to 30m in length. The tubes are inspected by passing an eddy current probe through the tubes from tube end to tube end. It is critical to know exactly which tube identification (row and column) is associated with each tube's data. This is controlled by a precision manipulator that provides the tube ID to the eddy current system. Historically there have been some instances where the manipulator incorrectly reported the tube ID. This can have serious consequences including lack of inspection of a tube, or if a pluggable indication is detected, the tube is likely to be mis-plugged thereby risking a primary to secondary leak.

  6. Word spotting with the gamma neural model

    NASA Astrophysics Data System (ADS)

    Fancourt, Craig; Euliano, Neil; Principe, Jose C.

    1995-04-01

    This paper discusses the application of the gamma neural model to word spotting. The gamma model is a dynamic neural model where the conventional tap delay line of the TDNN is replaced by a local recursive memory structure. This model is able to find the best memory depth for a given processing task when the number of taps in the memory is specified. It can also compensate for time warping. In our approach, word spotting is the detection of a signature (the keyword under analysis) in a noisy background (other words of continuous speech). Unlike other approaches, we do not segment the input, and the neural net learns over time how to recognize the patterns associated with a given word. We test two gamma model topologies for their sensitivity to time warping and amplitude variations.

  7. Fuzzy and neural control

    NASA Technical Reports Server (NTRS)

    Berenji, Hamid R.

    1992-01-01

    Fuzzy logic and neural networks provide new methods for designing control systems. Fuzzy logic controllers do not require a complete analytical model of a dynamic system and can provide knowledge-based heuristic controllers for ill-defined and complex systems. Neural networks can be used for learning control. In this chapter, we discuss hybrid methods using fuzzy logic and neural networks which can start with an approximate control knowledge base and refine it through reinforcement learning.

  8. Method of making straight fuel cell tubes

    DOEpatents

    Borglum, Brian P. (Edgewood, PA)

    2001-01-01

    A method and an apparatus for making straight fuel cell tubes are disclosed. Extruded tubes comprising powders of fuel cell material and a solvent are dried by rotating the extruded tubes. The rotation process provides uniform circumferential drying which results in uniform linear shrinkage of the tubes. The resultant dried tubes are very straight, thereby eliminating subsequent straightening steps required with conventional processes. The method is particularly useful for forming inner air electrode tubes of solid oxide fuel cells.

  9. ARTIFICIAL NEURAL NETWORKS IN PROTEIN

    E-print Network

    ARTIFICIAL NEURAL NETWORKS IN PROTEIN SECONDARY STRUCTURE PREDICTION: A CRITICAL REVIEW OF PRESENT;Final Project/ BIOMEDIN 231: Computational Molecular Biology Artificial Neural Network in Protein regulatory network; and artificial neural networks (ANN) and protein secondary structure prediction. Due

  10. Tube wall temperature monitoring technique

    SciTech Connect

    Granton, R.L.

    1985-07-01

    In 1977, Monsanto and Conoco undertook the construction of a new, modern technology ethylene plant at Chocolate Bayou, near Alvin, Texas. This plant included high severity cracking furnaces with potential tube wall temperatures considerably higher than any we had previously experienced. Furnace on-stream time between decokes, a factor in the economics of plant operation, was limited by tube wall temperature, thus requiring its accurate knowledge. Earlier work with other ethylene furnaces had also demonstrated our lack of knowledge concerning high temperature measurements in a furnace firebox environment. This had to change. An outside consultant was called upon to provide a threeday workshop on radiant tube temperature sensing. The workshop consisted of two days of formal training in the theory and practice of temperature measurement and one day of field training. This workshop was conducted at a site away from the plant. Approximately 20 engineers (manufacturing and technical groups) attended. The major topics covered by this workshop are as follows: radiant tube temperature sensing, radiation situation of radiant tubes, g.a. method: sample calculations, noncontact sensors: methods of specifying and purchasing, thermal imager strategies, calibration of noncontact sensors, avoiding problems with noncontact sensors, optical aids to radiant tube viewing, tube temperature management and its environmental implications, and contact temperature sensors.

  11. Flux tubes at finite temperature

    E-print Network

    Cea, Paolo; Cuteri, Francesca; Papa, Alessandro

    2015-01-01

    The chromoelectric field generated by a static quark-antiquark pair, with its peculiar tube-like shape, can be nicely described, at zero temperature, within the dual superconductor scenario for the QCD confining vacuum. In this work we investigate, by lattice Monte Carlo simulations of the SU(3) pure gauge theory, the fate of chromoelectric flux tubes across the deconfinement transition. We find that, as the temperature is increased towards and above the deconfinement temperature $T_c$, the amplitude of the field inside the flux tube gets smaller, while the shape of the flux tube does not vary appreciably across deconfinement. This scenario with flux-tube "evaporation" above $T_c$ has no correspondence in ordinary (type-II) superconductivity, where instead the transition to the phase with normal conductivity is characterized by a divergent fattening of flux tubes as the transition temperature is approached from below. We present also some evidence about the existence of flux-tube structures in the magnetic se...

  12. Flux tubes at finite temperature

    E-print Network

    Paolo Cea; Leonardo Cosmai; Francesca Cuteri; Alessandro Papa

    2015-11-05

    The chromoelectric field generated by a static quark-antiquark pair, with its peculiar tube-like shape, can be nicely described, at zero temperature, within the dual superconductor scenario for the QCD confining vacuum. In this work we investigate, by lattice Monte Carlo simulations of the SU(3) pure gauge theory, the fate of chromoelectric flux tubes across the deconfinement transition. We find that, as the temperature is increased towards and above the deconfinement temperature $T_c$, the amplitude of the field inside the flux tube gets smaller, while the shape of the flux tube does not vary appreciably across deconfinement. This scenario with flux-tube "evaporation" above $T_c$ has no correspondence in ordinary (type-II) superconductivity, where instead the transition to the phase with normal conductivity is characterized by a divergent fattening of flux tubes as the transition temperature is approached from below. We present also some evidence about the existence of flux-tube structures in the magnetic sector of the theory in the deconfined phase.

  13. Rijke tube with flexible walls

    NASA Astrophysics Data System (ADS)

    Mandre, Shreyas; Nguyen, Bao-Nhat; Li, Marvin

    2011-11-01

    Sound is excited spontaneously in a Rijke tube because the small temperature perturbations in an acoustic field interact with heat transfer from a heat source in the tube. The air particles near the heat source undergo a thermodynamic cyle converting heat to mechanical energy, which is heard as the sound emanating from the Rijke tube. This principle of energy conversion is used in thermoacoustic engines, and the main objective of this study is to improve their performance. The acoustic oscillations in the Rijke tube regulate the thermodynamic cycle, just as in conventional engines the cycle is controlled by the motion of a piston and the action of inlet and exit valves. The acoustic regulation in the Rijke tube, however, does not allow arbitrary control of the cycle in thermodynamic phase space. In this presentation, we introduce a new way of overcoming this limitation, one by using Rijke tubes with flexible walls. We will discuss how this modification allows for more general thermodynamic cycles to be executed by the air particles in the tube. This possibility, when used in thermoacoustic engines, opens a channel for further improving the engine performance.

  14. Neural crest and olfactory system: new prospective.

    PubMed

    Forni, Paolo E; Wray, Susan

    2012-10-01

    Sensory neurons in vertebrates are derived from two embryonic transient cell sources: neural crest (NC) and ectodermal placodes. The placodes are thickenings of ectodermal tissue that are responsible for the formation of cranial ganglia as well as complex sensory organs that include the lens, inner ear, and olfactory epithelium. The NC cells have been indicated to arise at the edges of the neural plate/dorsal neural tube, from both the neural plate and the epidermis in response to reciprocal interactions Moury and Jacobson (Dev Biol 141:243-253, 1990). NC cells migrate throughout the organism and give rise to a multitude of cell types that include melanocytes, cartilage and connective tissue of the head, components of the cranial nerves, the dorsal root ganglia, and Schwann cells. The embryonic definition of these two transient populations and their relative contribution to the formation of sensory organs has been investigated and debated for several decades (Basch and Bronner-Fraser, Adv Exp Med Biol 589:24-31, 2006; Basch et al., Nature 441:218-222, 2006) review (Baker and Bronner-Fraser, Dev Biol 232:1-61, 2001). Historically, all placodes have been described as exclusively derived from non-neural ectodermal progenitors. Recent genetic fate-mapping studies suggested a NC contribution to the olfactory placodes (OP) as well as the otic (auditory) placodes in rodents (Murdoch and Roskams, J Neurosci Off J Soc Neurosci 28:4271-4282, 2008; Murdoch et al., J Neurosci 30:9523-9532, 2010; Forni et al., J Neurosci Off J Soc Neurosci 31:6915-6927, 2011b; Freyer et al., Development 138:5403-5414, 2011; Katoh et al., Mol Brain 4:34, 2011). This review analyzes and discusses some recent developmental studies on the OP, placodal derivatives, and olfactory system. PMID:22773137

  15. Beta-Actin Is Required for Proper Mouse Neural Crest Ontogeny

    PubMed Central

    Tondeleir, Davina; Noelanders, Rivka; Bakkali, Karima; Ampe, Christophe

    2014-01-01

    The mouse genome consists of six functional actin genes of which the expression patterns are temporally and spatially regulated during development and in the adult organism. Deletion of beta-actin in mouse is lethal during embryonic development, although there is compensatory expression of other actin isoforms. This suggests different isoform specific functions and, more in particular, an important function for beta-actin during early mammalian development. We here report a role for beta-actin during neural crest ontogeny. Although beta-actin null neural crest cells show expression of neural crest markers, less cells delaminate and their migration arrests shortly after. These phenotypes were associated with elevated apoptosis levels in neural crest cells, whereas proliferation levels were unchanged. Specifically the pre-migratory neural crest cells displayed higher levels of apoptosis, suggesting increased apoptosis in the neural tube accounts for the decreased amount of migrating neural crest cells seen in the beta-actin null embryos. These cells additionally displayed a lack of membrane bound N-cadherin and dramatic decrease in cadherin-11 expression which was more pronounced in the pre-migratory neural crest population, potentially indicating linkage between the cadherin-11 expression and apoptosis. By inhibiting ROCK ex vivo, the knockout neural crest cells regained migratory capacity and cadherin-11 expression was upregulated. We conclude that the presence of beta-actin is vital for survival, specifically of pre-migratory neural crest cells, their proper emigration from the neural tube and their subsequent migration. Furthermore, the absence of beta-actin affects cadherin-11 and N-cadherin function, which could partly be alleviated by ROCK inhibition, situating the Rho-ROCK signaling in a feedback loop with cadherin-11. PMID:24409333

  16. Tubing drain valve

    SciTech Connect

    Soderberg, P.B.

    1987-02-24

    A method is described for operating a valve means. The valve means comprises a tubular piston movable within a tubular member suitable for use in a borehole pipe string to open and close a port through the wall of the tubular member. The method comprises: biassing the valve means in its closed position; pressurizing the interior of the piston to a predetermined pressure to overcome the biassing closed force and to actuate the valve means to its open position; biassing the valve means to its open position; and actuating the valve means to its closed position by engaging a first arm of a dog pivotally mounted on the piston with an engaging means insertable through the interior of the tubular piston; moving the piston relative to the tubular member; rotating the dog about its pivot to bring a second arm of the dog into contact with a detent in the tubular member; and applying sufficient force to the first arm to continue rotating the dog about the pivot, while engaging the detent with the second arm of the dog, in order to overcome the biassing open force to actuate the valve means to its closed position. A tubing drain valve suitable for use in a borehole pipe string, comprising: a sub suitable for incorporating within a borehole pipe string; and a port between the interior and the exterior of the sub; and valve means for opening and closing the port.

  17. [Anatomy of the eustachian tube].

    PubMed

    Böckers, A

    2013-06-01

    The auditory tube is part of a complex anatomical functional system, which even today is not completely explained. It plays a crucial role in the understanding of the pathogenesis of chronic middle ear infections and possible therapeutic interventions--particularly in infants. This paper summarizes the current knowledge of eustachian tube gross anatomy and histology, its peritubular structures and its topographic relationship to the internal carotid artery in adults. Anatomical aspects specific to infancy are related to their possible influence on tube function. PMID:23670679

  18. Acoustical studies on corrugated tubes

    NASA Astrophysics Data System (ADS)

    Balaguru, Rajavel

    Corrugated tubes and pipes offer greater global flexibility combined with local rigidity. They are used in numerous engineering applications such as vacuum cleaner hosing, air conditioning systems of aircraft and automobiles, HVAC control systems of heating ducts in buildings, compact heat exchangers, medical equipment and offshore gas and oil transportation flexible riser pipelines. Recently there has been a renewed research interest in analyzing the flow through a corrugated tube to understand the underlying mechanism of so called whistling, although the whistling in such a tube was identified in early twentieth century. The phenomenon of whistling in a corrugated tube is interesting because an airflow through a smooth walled tube of similar dimensions will not generate any whistling tones. Study of whistling in corrugated tubes is important because, it not only causes an undesirable noise problem but also results in flow-acoustic coupling. Such a coupling can cause significant structural vibrations due to flow-acoustic-structure interaction. This interaction would cause flow-induced vibrations that could result in severe damage to mechanical systems having corrugated tubes. In this research work, sound generation (whistling) in corrugated tubes due to airflow is analyzed using experimental as well as Computational Fluid Dynamics-Large Eddy Simulation (CFD-LES) techniques. Sound generation mechanisms resulting in whistling have been investigated. The whistling in terms of frequencies and sound pressure levels for different flow velocities are studied. The analytical and experimental studies are carried out to understand the influence of various parameters of corrugated tubes such as cavity length, cavity width, cavity depth, pitch, Reynolds numbers and number of corrugations. The results indicate that there is a good agreement between theoretically calculated, computationally predicted and experimentally measured whistling frequencies and sound pressure levels generated by flow through corrugated tubes. The computational studies are also extended for noise control through design of corrugated tubes such as design of leading and trailing edge spoilers, slanted walls for the cavities and presence of solid strip in the cavities of corrugations. Applications of this work to improve acoustical design of corrugated tubes are also discussed.

  19. PEG tubes: dealing with complications.

    PubMed

    Malhi, Hardip; Thompson, Rosie

    A percutaneous endoscopic gastronomy tube can be used to deliver nutrition, hydration and medicines directly into the patient's stomach. Patients will require a tube if they are unable to swallow safely, putting them at risk of aspiration of food, drink and medicines into their lungs. It is vital that nurses are aware of the complications that may arise when caring for a patient with a PEG tube. It is equally important that nurses know how to deal with these complications or from where tc seek advice. This article provides a quick troubleshooting guide to help nurses deal with complications that can arise with PEG feeding. PMID:26016095

  20. Nonsteady Flow in Capillary Tubes

    NASA Astrophysics Data System (ADS)

    Hara, Ayako

    2000-03-01

    Surface phenomena in the field of electron devices and the problem of how long. It takes plants to absorb water during their growth in hydroponic cultivation is attraching the attention of riseachers. However, the related study of non-steady flow in capillary tubes has a number of issues that require investigation. In response to this situation, we made attempted to assess nonsteady fiow in capillary tubes, the liquid rise time and other issues, using a motion equation that takes factors including the friction force of the tube and the surface tension into consideration.

  1. The Cosmic Background Explorer.

    ERIC Educational Resources Information Center

    Gulkis, Samuel; And Others

    1990-01-01

    Outlines the Cosmic Background Explorer (COBE) mission to measure celestial radiation. Describes the instruments used and experiments involving differential microwave radiometers, and a far infrared absolute spectrophotometer. (YP)

  2. In vivo optical modulation of neural signals using monolithically integrated two-dimensional neural probe arrays.

    PubMed

    Son, Yoojin; Jenny Lee, Hyunjoo; Kim, Jeongyeon; Shin, Hyogeun; Choi, Nakwon; Justin Lee, C; Yoon, Eui-Sung; Yoon, Euisik; Wise, Kensall D; Geun Kim, Tae; Cho, Il-Joo

    2015-01-01

    Integration of stimulation modalities (e.g. electrical, optical, and chemical) on a large array of neural probes can enable an investigation of important underlying mechanisms of brain disorders that is not possible through neural recordings alone. Furthermore, it is important to achieve this integration of multiple functionalities in a compact structure to utilize a large number of the mouse models. Here we present a successful optical modulation of in vivo neural signals of a transgenic mouse through our compact 2D MEMS neural array (optrodes). Using a novel fabrication method that embeds a lower cladding layer in a silicon substrate, we achieved a thin silicon 2D optrode array that is capable of delivering light to multiple sites using SU-8 as a waveguide core. Without additional modification to the microelectrodes, the measured impedance of the multiple microelectrodes was below 1 M? at 1 kHz. In addition, with a low background noise level (±25??V), neural spikes from different individual neurons were recorded on each microelectrode. Lastly, we successfully used our optrodes to modulate the neural activity of a transgenic mouse through optical stimulation. These results demonstrate the functionality of the 2D optrode array and its potential as a next-generation tool for optogenetic applications. PMID:26494437

  3. In vivo optical modulation of neural signals using monolithically integrated two-dimensional neural probe arrays

    NASA Astrophysics Data System (ADS)

    Son, Yoojin; Jenny Lee, Hyunjoo; Kim, Jeongyeon; Shin, Hyogeun; Choi, Nakwon; Justin Lee, C.; Yoon, Eui-Sung; Yoon, Euisik; Wise, Kensall D.; Geun Kim, Tae; Cho, Il-Joo

    2015-10-01

    Integration of stimulation modalities (e.g. electrical, optical, and chemical) on a large array of neural probes can enable an investigation of important underlying mechanisms of brain disorders that is not possible through neural recordings alone. Furthermore, it is important to achieve this integration of multiple functionalities in a compact structure to utilize a large number of the mouse models. Here we present a successful optical modulation of in vivo neural signals of a transgenic mouse through our compact 2D MEMS neural array (optrodes). Using a novel fabrication method that embeds a lower cladding layer in a silicon substrate, we achieved a thin silicon 2D optrode array that is capable of delivering light to multiple sites using SU-8 as a waveguide core. Without additional modification to the microelectrodes, the measured impedance of the multiple microelectrodes was below 1 M? at 1 kHz. In addition, with a low background noise level (±25??V), neural spikes from different individual neurons were recorded on each microelectrode. Lastly, we successfully used our optrodes to modulate the neural activity of a transgenic mouse through optical stimulation. These results demonstrate the functionality of the 2D optrode array and its potential as a next-generation tool for optogenetic applications.

  4. In vivo optical modulation of neural signals using monolithically integrated two-dimensional neural probe arrays

    PubMed Central

    Son, Yoojin; Jenny Lee, Hyunjoo; Kim, Jeongyeon; Shin, Hyogeun; Choi, Nakwon; Justin Lee, C.; Yoon, Eui-Sung; Yoon, Euisik; Wise, Kensall D.; Geun Kim, Tae; Cho, Il-Joo

    2015-01-01

    Integration of stimulation modalities (e.g. electrical, optical, and chemical) on a large array of neural probes can enable an investigation of important underlying mechanisms of brain disorders that is not possible through neural recordings alone. Furthermore, it is important to achieve this integration of multiple functionalities in a compact structure to utilize a large number of the mouse models. Here we present a successful optical modulation of in vivo neural signals of a transgenic mouse through our compact 2D MEMS neural array (optrodes). Using a novel fabrication method that embeds a lower cladding layer in a silicon substrate, we achieved a thin silicon 2D optrode array that is capable of delivering light to multiple sites using SU-8 as a waveguide core. Without additional modification to the microelectrodes, the measured impedance of the multiple microelectrodes was below 1 M? at 1 kHz. In addition, with a low background noise level (±25??V), neural spikes from different individual neurons were recorded on each microelectrode. Lastly, we successfully used our optrodes to modulate the neural activity of a transgenic mouse through optical stimulation. These results demonstrate the functionality of the 2D optrode array and its potential as a next-generation tool for optogenetic applications. PMID:26494437

  5. Anticipatory anxiety disrupts neural valuation during risky choice.

    PubMed

    Engelmann, Jan B; Meyer, Friederike; Fehr, Ernst; Ruff, Christian C

    2015-02-18

    Incidental negative emotions unrelated to the current task, such as background anxiety, can strongly influence decisions. This is most evident in psychiatric disorders associated with generalized emotional disturbances. However, the neural mechanisms by which incidental emotions may affect choices remain poorly understood. Here we study the effects of incidental anxiety on human risky decision making, focusing on both behavioral preferences and their underlying neural processes. Although observable choices remained stable across affective contexts with high and low incidental anxiety, we found a clear change in neural valuation signals: during high incidental anxiety, activity in ventromedial prefrontal cortex and ventral striatum showed a marked reduction in (1) neural coding of the expected subjective value (ESV) of risky options, (2) prediction of observed choices, (3) functional coupling with other areas of the valuation system, and (4) baseline activity. At the same time, activity in the anterior insula showed an increase in coding the negative ESV of risky lotteries, and this neural activity predicted whether the risky lotteries would be rejected. This pattern of results suggests that incidental anxiety can shift the focus of neural valuation from possible positive consequences to anticipated negative consequences of choice options. Moreover, our findings show that these changes in neural value coding can occur in the absence of changes in overt behavior. This suggest a possible pathway by which background anxiety may lead to the development of chronic reward desensitization and a maladaptive focus on negative cognitions, as prevalent in affective and anxiety disorders. PMID:25698745

  6. Tube-wave seismic imaging

    DOEpatents

    Korneev, Valeri A. (Lafayette, CA); Bakulin, Andrey (Houston, TX)

    2009-10-13

    The detailed analysis of cross well seismic data for a gas reservoir in Texas revealed two newly detected seismic wave effects, recorded approximately 2000 feet above the reservoir. A tube-wave (150) is initiated in a source well (110) by a source (111), travels in the source well (110), is coupled to a geological feature (140), propagates (151) through the geological feature (140), is coupled back to a tube-wave (152) at a receiver well (120), and is and received by receiver(s) (121) in either the same (110) or a different receiving well (120). The tube-wave has been shown to be extremely sensitive to changes in reservoir characteristics. Tube-waves appear to couple most effectively to reservoirs where the well casing is perforated, allowing direct fluid contact from the interior of a well case to the reservoir.

  7. Tube-wave seismic imaging

    DOEpatents

    Korneev, Valeri A [LaFayette, CA

    2009-05-05

    The detailed analysis of cross well seismic data for a gas reservoir in Texas revealed two newly detected seismic wave effects, recorded approximately 2000 feet above the reservoir. A tube-wave (150) is initiated in a source well (110) by a source (111), travels in the source well (110), is coupled to a geological feature (140), propagates (151) through the geological feature (140), is coupled back to a tube-wave (152) at a receiver well (120), and is and received by receiver(s) (121) in either the same (110) or a different receiving well (120). The tube-wave has been shown to be extremely sensitive to changes in reservoir characteristics. Tube-waves appear to couple most effectively to reservoirs where the well casing is perforated, allowing direct fluid contact from the interior of a well case to the reservoir.

  8. Gastrostomy feeding tube - pump - child

    MedlinePLUS

    ... becomes hard or swollen after a feeding, try venting or "burping" the tube or button: Attach an ... Kowalski MT, Rosdahl CB. Diet therapy and special diets. In: ... 10th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2011: ...

  9. Steam generator tube rupture study

    E-print Network

    Free, Scott Thomas

    1986-01-01

    This report describes our investigation of steam generator behavior during a postulated tube rupture accident. Our study was performed using the steam generator, thermal-hydraulic analysis code THERMIT-UTSG. The purpose ...

  10. Pulsed Drift Tube Accelerator

    SciTech Connect

    Faltens, A.

    2004-10-25

    The pulsed drift-tube accelerator (DTA) concept was revived by Joe Kwan and John Staples and is being considered for the HEDP/WDM application. It could be used to reach the full energy or as an intermediate accelerator between the diode and a high gradient accelerator such as multi-beam r.f. In the earliest LBNL HIF proposals and conceptual drivers it was used as an extended injector to reach energies where an induction linac with magnetic quadrupoles is the best choice. For HEDP, because of the very short pulse duration, the DTA could provide an acceleration rate of about 1MV/m. This note is divided into two parts: the first, a design based on existing experience; the second, an optimistic extrapolation. The first accelerates 16 parallel K{sup +} beams at a constant line charge density of 0.25{micro} C/m per beam to 10 MeV; the second uses a stripper and charge selector at around 4MeV followed by further acceleration to reach 40 MeV. Both benefit from more compact sources than the present 2MV injector source, although that beam is the basis of the first design and is a viable option. A pulsed drift-tube accelerator was the first major HIF experiment at LBNL. It was designed to produce a 2{micro}s rectangular 1 Ampere C{sub s}{sup +} beam at 2MeV. It ran comfortably at 1.6MeV for several years, then at lower voltages and currents for other experiments, and remnants of that experiment are in use in present experiments, still running 25 years later. The 1A current, completely equivalent to 1.8A K{sup +}, was chosen to be intermediate between the beamlets appropriate for a multi-beam accelerator, and a single beam of, say, 10A, at injection energies. The original driver scenarios using one large beam on each side of the reactor rapidly fell out of favor because of the very high transverse and longitudinal fields from the beam space charge, circa 1MV/cm and 250 kV/cm respectively, near the chamber and because of aberrations in focusing a large diameter beam down to a 1mm radius spot at a distance of 10m. Almost all subsequent work and the present concept have invoked multiple beams. For HEDP the major differences are that the focal distance can be centimeters instead of meters, provided strong-enough lenses exist and they do, thereby allowing much higher transverse and longitudinal emittances than driver concepts, and focusing parallel small beams is easier than one big beam.

  11. The IBEX background monitor

    E-print Network

    Crew, Geoffrey B.

    The IBEX Background Monitor (IBaM) provides a small and lightweight method for independently measuring IBEX’s high-energy proton background by integrating the flux of >~14 keV protons over a ~7° conical FOV. The IBaM is ...

  12. INDIAN BACKGROUNDS Patuxent Wildlife

    E-print Network

    INDIAN BACKGROUNDS of the Patuxent Wildlife Research Center |./«arine'a(Megical Laboratory NOV 19 of Sport Fisheries and Wildlife Circular 138 #12;#12;INDIAN BACKGROUNDS of the Patuxent Wildlife Research of Indian Relics The Indian artifacts on display in the C. Hart Merriam Laboratory were collected

  13. Correlators in nontrivial backgrounds

    SciTech Connect

    Mello Koch, Robert de; Ives, Norman; Stephanou, Michael

    2009-01-15

    Operators in N=4 super Yang-Mills theory with an R-charge of O(N{sup 2}) are dual to backgrounds which are asymtotically AdS{sub 5}xS{sup 5}. In this article we develop efficient techniques that allow the computation of correlation functions in these backgrounds. We find that (i) contractions between fields in the string words and fields in the operator creating the background are the field theory accounting of the new geometry, (ii) correlation functions of probes in these backgrounds are given by the free field theory contractions but with rescaled propagators and (iii) in these backgrounds there are no open string excitations with their special end point interactions; we have only closed string excitations.

  14. Critical Branching Neural Networks

    ERIC Educational Resources Information Center

    Kello, Christopher T.

    2013-01-01

    It is now well-established that intrinsic variations in human neural and behavioral activity tend to exhibit scaling laws in their fluctuations and distributions. The meaning of these scaling laws is an ongoing matter of debate between isolable causes versus pervasive causes. A spiking neural network model is presented that self-tunes to critical…

  15. Venturi Tube with Varying Mass Flow

    NASA Technical Reports Server (NTRS)

    Regenscheit, B.

    1948-01-01

    Measurements on three tubes with flow regulated by suction at the trainling edge of the tube are described. It was possible to vary the mass of air flowing through the tube over a large range. Such tubes could be used for shrouded propellers.

  16. Nasal Bridles for Securing Nasoenteric Tubes: A Meta-Analysis

    PubMed Central

    Bechtold, Matthew L.; Nguyen, Douglas L.; Palmer, Lena B.; Kiraly, Laszlo N.; Martindale, Robert G.; McClave, Stephen A.

    2015-01-01

    Background Nasoenteric feeding tubes may easily become dislodged due to patient mental status, transfers, or positional changes. Nasal bridles were introduced to provide a better, more reliable system to secure these tubes. This meta-analysis was performed to evaluate the effectiveness of nasal bridles compared with the traditional method of adhesive tape alone in securing enteral feeding tubes. Materials and Methods Multiple databases were searched (October 2013). All studies that evaluated the use of nasal bridles in adult patients were included in the analysis. Meta-analysis for the outcomes from use of a nasal bridle vs the more traditional method of adhesive tape alone for securing nasoenteric tubes was analyzed by calculating pooled estimates of dislodgement, skin complications, and sinusitis. Statistical analysis was performed using RevMan 5.1. Results Six studies (n = 594) met the inclusion criteria. Use of a nasal bridle for securing enteral tubes resulted in a statistically significant reduction in tube dislodgement compared with traditional adhesive tape alone (odds ratio [OR], 0.16; 95% confidence interval [CI], 0.10–0.27; P < .01). The use of nasal bridles was associated with a higher rate of skin complications compared with traditional adhesive tape (OR, 4.27; 95% CI, 1.79–10.23; P < .01). Incidence of sinusitis was no different between the 2 groups (OR, 0.26; 95% CI, 0.03–2.28; P = .22). Conclusion Nasal bridles appear to be more effective at securing nasoenteric tubes and preventing dislodgement than traditional use of tape alone. PMID:25606648

  17. Snail mediates medial-lateral patterning of the ascidian neural plate.

    PubMed

    Hudson, Clare; Sirour, Cathy; Yasuo, Hitoyoshi

    2015-07-15

    The ascidian neural plate exhibits a regular, grid-like arrangement of cells. Patterning of the neural plate across the medial-lateral axis is initiated by bilateral sources of Nodal signalling, such that Nodal signalling induces expression of lateral neural plate genes and represses expression of medial neural plate genes. One of the earliest lateral neural plate genes induced by Nodal signals encodes the transcription factor Snail. Here, we show that Snail is a critical downstream factor mediating this Nodal-dependent patterning. Using gain and loss of function approaches, we show that Snail is required to repress medial neural plate gene expression at neural plate stages and to maintain the lateral neural tube genetic programme at later stages. A comparison of these results to those obtained following Nodal gain and loss of function indicates that Snail mediates a subset of Nodal functions. Consistently, overexpression of Snail can partially rescue a Nodal inhibition phenotype. We conclude that Snail is an early component of the gene regulatory network, initiated by Nodal signals, that patterns the ascidian neural plate. PMID:25962578

  18. Flow instabilities of magnetic flux tubes. I. Perpendicular flow

    NASA Astrophysics Data System (ADS)

    Schüssler, M.; Ferriz Mas, A.

    2007-02-01

    Context: The stability properties of filamentary magnetic structures are relevant for the storage and dynamics of magnetic fields in stellar convection zones and possibly also in other astrophysical contexts. Aims: In a series of papers we study the effect of external and internal flows on the stability of magnetic flux tubes. In this paper we consider the effect of a flow perpendicular to a straight, horizontal flux tube embedded in a gravitationally stratified fluid. The flow acts on the flux tube by exerting an aerodynamic drag force and by modifying the pressure stratification in the background medium. Methods: We carry out a Lagrangian linear stability analysis in the framework of the approximation of thin magnetic flux tubes. Results: The external flow can drive monotonic and oscillatory instability (overstability). The stability condition depends on direction and magnitude of the external velocity as well as on its first and second derivatives with respect to depth. The range of the flow-driven instabilities typically extends to modes with much shorter wavelengths than for the buoyancy-driven undulatory Parker instability. Conclusions: .Perpendicular flows with Alfvénic Mach number of order unity can drive monotonic as well as oscillatory instability of thin magnetic flux tubes. Such instability can affect the storage of magnetic flux in stellar interiors.

  19. Casimir interactions between magnetic flux tubes in a dense lattice

    NASA Astrophysics Data System (ADS)

    Mazur, Dan; Heyl, Jeremy S.

    2015-03-01

    We use the worldline numerics technique to study a cylindrically symmetric model of magnetic flux tubes in a dense lattice and the nonlocal Casimir forces acting between regions of magnetic flux. Within a superconductor the magnetic field is constrained within magnetic flux tubes and if the background magnetic field is on the order the quantum critical field strength, Bk=m/2 e =4.4 ×1013 Gauss, the magnetic field is likely to vary rapidly on the scales where QED effects are important. In this paper, we construct a cylindrically symmetric toy model of a flux tube lattice in which the nonlocal influence of QED on neighboring flux tubes is taken into account. We compute the effective action densities using the worldline numerics technique. The numerics predict a greater effective energy density in the region of the flux tube, but a smaller energy density in the regions between the flux tubes compared to a locally constant-field approximation. We also compute the interaction energy between a flux tube and its neighbors as the lattice spacing is reduced from infinity. Because our flux tubes exhibit compact support, this energy is entirely nonlocal and predicted to be zero in local approximations such as the derivative expansion. This Casimir-Polder energy can take positive or negative values depending on the distance between the flux tubes, and it may cause the flux tubes in neutron stars to form bunches. In addition to the above results we also discuss two important subtleties of determining the statistical uncertainties within the worldline numerics technique. Firstly, the distributions generated by the worldline ensembles are highly non-Gaussian, and so the standard error in the mean is not a good measure of the statistical uncertainty. Secondly, because the same ensemble of worldlines is used to compute the Wilson loops at different values of T and xcm, the uncertainties associated with each computed value of the integrand are strongly correlated. We recommend a form of jackknife analysis which deals with both of these problems.

  20. Machine Learning Srihari Neural Networks

    E-print Network

    Machine Learning Srihari Neural Networks Introduction Sargur Srihari #12;Machine Learning in Neural Networks 6. Mixture Density Networks 7. Bayesian Neural Networks 2 #12;Machine Learning xi + w j 0 (1) + wk0 (2) #12;Machine Learning Srihari SVM versus Neural Networks

  1. Casimir Effect in Hemisphere Capped Tubes

    NASA Astrophysics Data System (ADS)

    Bezerra de Mello, E. R.; Saharian, A. A.

    2015-08-01

    In this paper we investigate the vacuum densities for a massive scalar field with general curvature coupling in background of a (2 + 1)-dimensional spacetime corresponding to a cylindrical tube with a hemispherical cap. A complete set of mode functions is constructed and the positive-frequency Wightman function is evaluated for both the cylindrical and hemispherical subspaces. On the base of this, the vacuum expectation values of the field squared and energy-momentum tensor are investigated. The mean field squared and the normal stress are finite on the boundary separating two subspaces, whereas the energy density and the parallel stress diverge as the inverse power of the distance from the boundary. For a conformally coupled field, the vacuum energy density is negative on the cylindrical part of the space. On the hemisphere, it is negative near the top and positive close to the boundary. In the case of minimal coupling the energy density on the cup is negative. On the tube it is positive near the boundary and negative at large distances. Though the geometries of the subspaces are different, the Casimir pressures on the separate sides of the boundary are equal and the net Casimir force vanishes. The results obtained may be applied to capped carbon nanotubes described by an effective field theory in the long-wavelength approximation.

  2. The Cosmic Background Radiation

    E-print Network

    George Smoot; Douglas Scott

    1997-11-08

    We summarise the current status of cosmic microwave background spectrum and anisotropy measurements, and their theoretical interpretation. This is the update of the mini-review for the 1997 web-version of the Review of Particle Properties.

  3. Introduction Biological Background

    E-print Network

    Mahaffy, Joseph M.

    @mail.sdsu.eduUBC Biomath Seminar -- (1/39) #12;Introduction Biological Background Mathematical Models Conclusions Tunicate ­ Ciona intestinalis Ciona intestinalis ­ Tunicate ­ Sea Squirt Joseph M. Mahaffy, jmahaffy

  4. Proteomics: General Background

    E-print Network

    Grosu, Radu

    Proteomics: General Background Michael Hadjiargyrou Department of Biomedical Engineering #12;What is proteomics? · Study of the Proteome: Field that utilizes protein sequences, expression and structure, large scale manner · may also involve bioinformatic analysis and storage of data #12;Proteomics

  5. The Cosmic Microwave Background

    E-print Network

    Joseph Silk

    2002-12-12

    I review the discovery of the temperature fluctuations in the cosmic microwave background radiation. The underlying theory and the implications for cosmology are reviewed, and I describe the prospects for future progress.

  6. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Arch tubes, water bar tubes, circulators and... MAINTENANCE STANDARDS Boilers and Appurtenances Washing Boilers § 230.61 Arch tubes, water bar tubes... water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and...

  7. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Arch tubes, water bar tubes, circulators and... MAINTENANCE STANDARDS Boilers and Appurtenances Washing Boilers § 230.61 Arch tubes, water bar tubes... water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and...

  8. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Arch tubes, water bar tubes, circulators and... MAINTENANCE STANDARDS Boilers and Appurtenances Washing Boilers § 230.61 Arch tubes, water bar tubes... water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and...

  9. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Arch tubes, water bar tubes, circulators and... MAINTENANCE STANDARDS Boilers and Appurtenances Washing Boilers § 230.61 Arch tubes, water bar tubes... water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and...

  10. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Arch tubes, water bar tubes, circulators and... MAINTENANCE STANDARDS Boilers and Appurtenances Washing Boilers § 230.61 Arch tubes, water bar tubes... water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and...

  11. Dynamics of neural cryptography

    NASA Astrophysics Data System (ADS)

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-01

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  12. Dynamics of neural cryptography

    SciTech Connect

    Ruttor, Andreas; Kinzel, Wolfgang; Kanter, Ido

    2007-05-15

    Synchronization of neural networks has been used for public channel protocols in cryptography. In the case of tree parity machines the dynamics of both bidirectional synchronization and unidirectional learning is driven by attractive and repulsive stochastic forces. Thus it can be described well by a random walk model for the overlap between participating neural networks. For that purpose transition probabilities and scaling laws for the step sizes are derived analytically. Both these calculations as well as numerical simulations show that bidirectional interaction leads to full synchronization on average. In contrast, successful learning is only possible by means of fluctuations. Consequently, synchronization is much faster than learning, which is essential for the security of the neural key-exchange protocol. However, this qualitative difference between bidirectional and unidirectional interaction vanishes if tree parity machines with more than three hidden units are used, so that those neural networks are not suitable for neural cryptography. In addition, the effective number of keys which can be generated by the neural key-exchange protocol is calculated using the entropy of the weight distribution. As this quantity increases exponentially with the system size, brute-force attacks on neural cryptography can easily be made unfeasible.

  13. Reconfigurable Control Design with Neural Network Augmentation for a Modified F-15 Aircraft

    NASA Technical Reports Server (NTRS)

    Burken, John J.

    2007-01-01

    The viewgraphs present background information about reconfiguration control design, design methods used for paper, control failure survivability results, and results and time histories of tests. Topics examined include control reconfiguration, general information about adaptive controllers, model reference adaptive control (MRAC), the utility of neural networks, radial basis functions (RBF) neural network outputs, neurons, and results of investigations of failures.

  14. Hobetron current regulating switch tube

    SciTech Connect

    True, R.B.; Hansen, R.J.; Deb, D.N.; Good, G.R.; Reass, W.A.

    1999-07-01

    This paper describes a novel high power electron tube that can hold off voltages up to hundreds of kilovolts, and switch hundreds of amps of current. They call the divide the Hobertron since it utilizes a hollow electron beam. Unlike magnetron injection gun (MIG) switch tubes, it does not require a magnet. Further, it uses nonintercepting control laments, and a dispenser cathode for long life and reliability. Finally, it features a double walled Faraday cage collector for high power dissipation capability. Current is very tightly controlled against changes in voltage across the switch (it is an almost perfect pentode), thus this tube is ideally suited for direct series switching applications. In the paper, various Hobertron designs, and the computer codes and methods used to create them, will be described.

  15. Failure analysis of brass tubes

    SciTech Connect

    Lawrence, S.J.; Bodnar, R.L.

    1997-02-01

    The 1996 Jacquet Lucas Award for Excellence in Metallography was won by Samuel J. Lawrence and Richard L. Bodnar for their analysis of cracks in Admiralty brass cooling tubes, which are part of a heat exchanger in a turbogenerator that provides electricity to a manufacturing plant. A mixture of non-recirculating city and spring pit water flows through bundles of tubes to cool the oil in which they are immersed. However, a problem developed when several of the brass tubes cracked transversely, allowing cooling water to mix with the oil. This award-winning entry in the ASM/IMS competition shows how the metallographers analyzed the cracks, and what the results were.

  16. Coiled tubing; Operations and services

    SciTech Connect

    Brown, P.T.; Wimberly, R.D.

    1992-10-01

    Oil and gas wells that flow on initial completion eventually reach a condition of liquid loading that kills the wells. This results form declining reservoir pressure, decreased gas volume (velocity), increased water production and other factors that cause liquids to accumulate at the bottom of the well and exert back pressure on the formation. This restricts or in some cases prevents fluid entry into the wellbore form the formation. Flowing production can be restored or increased by reducing surface backpressure, well bore stimulation, pressure maintenance or by installing a string of smaller diameter tubing. This paper reports on installation (hanging off) of a concentric string of coiled tubing inside existing production tubing which is an economically viable, safe, convenient and effective alterative for returning some of these liquid loaded )logged-up) wells to flowing status.

  17. Tube formation in fluid membranes

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Sknepnek, Rastko; Schwarz, Jennifer; Bowick, Mark

    2014-03-01

    Consider a point force pulling on a fluid membrane. As the magnitude of the force increases, there is a first-order shape transition from nontubular to tubular with a force barrier in between. Motivated by tube formation in endocytosis in yeast, we generalize this problem by including additional force components and steric interactions. Both new ingredients are a consequence of the underlying actin cytoskeletal network, which exerts active forces on the cell membrane to deform it into a tube. We study this generalized problem using variational and Monte Carlo methods in order to quantify endocytosis in yeast.

  18. Opposed slant tube diabatic sorber

    DOEpatents

    Erickson, Donald C.

    2004-01-20

    A sorber comprised of at least three concentric coils of tubing contained in a shell with a flow path for liquid sorbent in one direction, a flow path for heat transfer fluid which is in counter-current heat exchange relationship with sorbent flow, a sorbate vapor port in communication with at least one of sorbent inlet or exit ports, wherein each coil is coiled in opposite direction to those coils adjoining it, whereby the opposed slant tube configuration is achieved, with structure for flow modification in the core space inside the innermost coil.

  19. 21 CFR 868.5800 - Tracheostomy tube and tube cuff.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...tracheostomy tube. The cuff is used to prevent the patient's aspiration of substances, such as blood or vomit, or to provide a means for positive-pressure ventilation of the patient. This device is made of either stainless steel or plastic....

  20. Contextual behavior and neural circuits

    PubMed Central

    Lee, Inah; Lee, Choong-Hee

    2013-01-01

    Animals including humans engage in goal-directed behavior flexibly in response to items and their background, which is called contextual behavior in this review. Although the concept of context has long been studied, there are differences among researchers in defining and experimenting with the concept. The current review aims to provide a categorical framework within which not only the neural mechanisms of contextual information processing but also the contextual behavior can be studied in more concrete ways. For this purpose, we categorize contextual behavior into three subcategories as follows by considering the types of interactions among context, item, and response: contextual response selection, contextual item selection, and contextual item–response selection. Contextual response selection refers to the animal emitting different types of responses to the same item depending on the context in the background. Contextual item selection occurs when there are multiple items that need to be chosen in a contextual manner. Finally, when multiple items and multiple contexts are involved, contextual item–response selection takes place whereby the animal either chooses an item or inhibits such a response depending on item–context paired association. The literature suggests that the rhinal cortical regions and the hippocampal formation play key roles in mnemonically categorizing and recognizing contextual representations and the associated items. In addition, it appears that the fronto-striatal cortical loops in connection with the contextual information-processing areas critically control the flexible deployment of adaptive action sets and motor responses for maximizing goals. We suggest that contextual information processing should be investigated in experimental settings where contextual stimuli and resulting behaviors are clearly defined and measurable, considering the dynamic top-down and bottom-up interactions among the neural systems for contextual behavior. PMID:23675321

  1. The Cosmic Background Explorer

    NASA Technical Reports Server (NTRS)

    Gulkis, Samuel; Lubin, Philip M.; Meyer, Stephan S.; Silverberg, Robert F.

    1990-01-01

    The Cosmic Background Explorer (CBE), NASA's cosmological satellite which will observe a radiative relic of the big bang, is discussed. The major questions connected to the big bang theory which may be clarified using the CBE are reviewed. The satellite instruments and experiments are described, including the Differential Microwave Radiometer, which measures the difference between microwave radiation emitted from two points on the sky, the Far-Infrared Absolute Spectrophotometer, which compares the spectrum of radiation from the sky at wavelengths from 100 microns to one cm with that from an internal blackbody, and the Diffuse Infrared Background Experiment, which searches for the radiation from the earliest generation of stars.

  2. Neural constraints on learning

    PubMed Central

    Sadtler, Patrick T.; Quick, Kristin M.; Golub, Matthew D.; Chase, Steven M.; Ryu, Stephen I.; Tyler-Kabara, Elizabeth C.; Yu, Byron M.; Batista, Aaron P.

    2014-01-01

    Motor, sensory, and cognitive learning require networks of neurons to generate new activity patterns. Because some behaviors are easier to learn than others1,2, we wondered if some neural activity patterns are easier to generate than others. We asked whether the existing network constrains the patterns that a subset of its neurons is capable of exhibiting, and if so, what principles define the constraint. We employed a closed-loop intracortical brain-computer interface (BCI) learning paradigm in which Rhesus monkeys controlled a computer cursor by modulating neural activity patterns in primary motor cortex. Using the BCI paradigm, we could specify and alter how neural activity mapped to cursor velocity. At the start of each session, we observed the characteristic activity patterns of the recorded neural population. These patterns comprise a low-dimensional space (termed the intrinsic manifold, or IM) within the high-dimensional neural firing rate space. They presumably reflect constraints imposed by the underlying neural circuitry. We found that the animals could readily learn to proficiently control the cursor using neural activity patterns that were within the IM. However, animals were less able to learn to proficiently control the cursor using activity patterns that were outside of the IM. This result suggests that the existing structure of a network can shape learning. On the timescale of hours, it appears to be difficult to learn to generate neural activity patterns that are not consistent with the existing network structure. These findings offer a network-level explanation for the observation that we are more readily able to learn new skills when they are related to the skills that we already possess3,4. PMID:25164754

  3. Neural network applications

    NASA Technical Reports Server (NTRS)

    Padgett, Mary L.; Desai, Utpal; Roppel, T.A.; White, Charles R.

    1993-01-01

    A design procedure is suggested for neural networks which accommodates the inclusion of such knowledge-based systems techniques as fuzzy logic and pairwise comparisons. The use of these procedures in the design of applications combines qualitative and quantitative factors with empirical data to yield a model with justifiable design and parameter selection procedures. The procedure is especially relevant to areas of back-propagation neural network design which are highly responsive to the use of precisely recorded expert knowledge.

  4. High school music classes enhance the neural processing of speech

    PubMed Central

    Tierney, Adam; Krizman, Jennifer; Skoe, Erika; Johnston, Kathleen; Kraus, Nina

    2013-01-01

    Should music be a priority in public education? One argument for teaching music in school is that private music instruction relates to enhanced language abilities and neural function. However, the directionality of this relationship is unclear and it is unknown whether school-based music training can produce these enhancements. Here we show that 2 years of group music classes in high school enhance the neural encoding of speech. To tease apart the relationships between music and neural function, we tested high school students participating in either music or fitness-based training. These groups were matched at the onset of training on neural timing, reading ability, and IQ. Auditory brainstem responses were collected to a synthesized speech sound presented in background noise. After 2 years of training, the neural responses of the music training group were earlier than at pre-training, while the neural timing of students in the fitness training group was unchanged. These results represent the strongest evidence to date that in-school music education can cause enhanced speech encoding. The neural benefits of musical training are, therefore, not limited to expensive private instruction early in childhood but can be elicited by cost-effective group instruction during adolescence. PMID:24367339

  5. High school music classes enhance the neural processing of speech.

    PubMed

    Tierney, Adam; Krizman, Jennifer; Skoe, Erika; Johnston, Kathleen; Kraus, Nina

    2013-01-01

    Should music be a priority in public education? One argument for teaching music in school is that private music instruction relates to enhanced language abilities and neural function. However, the directionality of this relationship is unclear and it is unknown whether school-based music training can produce these enhancements. Here we show that 2 years of group music classes in high school enhance the neural encoding of speech. To tease apart the relationships between music and neural function, we tested high school students participating in either music or fitness-based training. These groups were matched at the onset of training on neural timing, reading ability, and IQ. Auditory brainstem responses were collected to a synthesized speech sound presented in background noise. After 2 years of training, the neural responses of the music training group were earlier than at pre-training, while the neural timing of students in the fitness training group was unchanged. These results represent the strongest evidence to date that in-school music education can cause enhanced speech encoding. The neural benefits of musical training are, therefore, not limited to expensive private instruction early in childhood but can be elicited by cost-effective group instruction during adolescence. PMID:24367339

  6. BACKGROUND RESEARCH SAMPLE CODE

    E-print Network

    Gray, Jeffrey G.

    . This type of diabetes is normally seen in children at a very young age. Type II diabetes, on the other handBACKGROUND RESEARCH SAMPLE CODE INTRODUCTION APPLICATION MATERIALS ABSTRACT PURPOSE Diabetes is when the body does not properly use or store the glucose (Mayoclinic). There are two types of diabetes

  7. China: Background Notes Series.

    ERIC Educational Resources Information Center

    Reams, Joanne Reppert

    Concise background information on the People's Republic of China is provided. The publication begins with a profile of the country, outlining the people, geography, economy, and membership in international organizations. The bulk of the document then discusses in more detail China's people, geography, history, government, education, economy, and…

  8. Monitored background radiometer

    NASA Technical Reports Server (NTRS)

    Ruel, C.; Larouche, M.; Donato, M.

    1986-01-01

    The infrared (IR) testing of the Olympus thermal model has provided a capability to perform cost effective thermal balance testing of satellites and satellite components. A high-accuracy monitored background radiometer was developed for the measurement of absorbed radiation heat flux encountered during IR thermal vacuum testing of spacecraft. The design, development, and calibration of this radiometer is described.

  9. Berkeley Low Background Facility

    NASA Astrophysics Data System (ADS)

    Thomas, K. J.; Smith, A. R.; Poon, A. W. P.; Chan, Y. D.; Norman, E. B.; Lesko, K. T.

    2015-08-01

    The Berkeley Low Background Facility (BLBF) at Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California provides low background gamma spectroscopy services to a wide array of experiments and projects. The analysis of samples takes place within two unique facilities; locally within a carefully-constructed, low background laboratory on the surface at LBNL and at the Sanford Underground Research Facility (SURF) in Lead, SD. These facilities provide a variety of gamma spectroscopy services to low background experiments primarily in the form of passive material screening for primordial radioisotopes (U, Th, K) or common cosmogenic/anthropogenic products; active screening via neutron activation analysis for U,Th, and K as well as a variety of stable isotopes; and neutron flux/beam characterization measurements through the use of monitors. A general overview of the facilities, services, and sensitivities will be presented. Recent activities and upgrades will also be described including an overview of the recently installed counting system at SURF (recently relocated from Oroville, CA in 2014), the installation of a second underground counting station at SURF in 2015, and future plans. The BLBF is open to any users for counting services or collaboration on a wide variety of experiments and projects.

  10. PANDEMIC INFLUENZA background briefing

    E-print Network

    Rambaut, Andrew

    PANDEMIC INFLUENZA background briefing Biomedicine Forum 5 November 2008 compiled by David Evans, Dave Carr, David Lynn and Phil Green Transmission electron micrograph of Influenza A virus (Wellcome influenza!' Page 2 #12;Consequences of an influenza pandemic THE PANDEMIC THREAT DEATH If the next pandemic

  11. EBSD Images Theoretical Background

    E-print Network

    Psaltis, Demetri

    /s assuming a constant growth rate on the 20 first seconds. Bad quality welds were produced by adding grease-tomography. Figure 8 Transverse slice of the bad quality weld observed through X-ray micro- tomography. The poresMotivation EBSD Images Theoretical Background Defects in the Weld Grain Growth Low Speed Welding

  12. Building Background Knowledge

    ERIC Educational Resources Information Center

    Fisher, Douglas; Ross, Donna; Grant, Maria

    2010-01-01

    Too often, students enter our classrooms with insufficient knowledge of physical science. As a result, they have a difficult time understanding content in texts, lectures, and laboratory activities. This lack of background knowledge can have an impact on their ability to ask questions and wonder--both key components of inquiry. In this article,…

  13. Minimizing Computation in Convolutional Neural Networks

    E-print Network

    Cong, Jason "Jingsheng"

    Minimizing Computation in Convolutional Neural Networks Jason Cong and Bingjun Xiao Computer. Convolutional Neural Networks (CNNs) have been successfully used for many computer vision applications. It would Convolutional neural networks (CNNs) were extended from artificial neural networks (ANNs) and customized

  14. Elegance: Genetic Algorithms in Neural Reinforcement Control

    E-print Network

    Spronck, Pieter

    Elegance: Genetic Algorithms in Neural Reinforcement Control Pieter Spronck Graduation committee: Genetic Algorithms in Neural Reinforcement Control. Graduation thesis (Master's degree). Delft University intelligence, genetic algorithms, neural control, neural networks, non-linear systems, reinforcement control

  15. Mechanical support for straw tubes

    SciTech Connect

    Joestlein, H.

    1990-03-11

    A design is proposed for mounting a large number of straw tubes to form an SSC central tracking chamber. The assembly is precise and of very low mass. The fabrication is modular and can be carried out with a minimum of tooling and instrumentation. Testing of modules is possible prior to the final assembly. 4 figs.

  16. Tube joint leak repair coupling

    NASA Technical Reports Server (NTRS)

    Ferguson, W. B.

    1968-01-01

    Tube joint leak repair coupling consists of 2 split seals, 1 male split nut, 1 female split nut, and two aligning pins. Each split nut consists of 2 half-shell sections which, when engaged, are held together by a dovetail joint and an aligning pin.

  17. Kundt's Tube Experiment Using Smartphones

    ERIC Educational Resources Information Center

    Parolin, Sara Orsola; Pezzi, Giovanni

    2015-01-01

    This article deals with a modern version of Kundt's tube experiment. Using economic instruments and a couple of smartphones, it is possible to "see" nodes and antinodes of standing acoustic waves in a column of vibrating air and to measure the speed of sound.

  18. Apparatus for connecting aligned abutted tubes

    DOEpatents

    Williams, R.E.

    1984-11-29

    An apparatus for connecting abutted tubes and for maintaining their rotary alignment during connection. The apparatus comprises first and second tubes, a rotation prevention element, a collar and a retainer. Each tube has inside and outside walls, and first and second ends, each end having an inside and outside edge. The first tube has portions defining a first plurality of cavities located at the outside edge of its first end. An external threaded portion is on the outside wall of the first tube and next to the first plurality of cavities. The second tube has portions defining a second plurality of cavities located at the outside edge of its first end. The first plurality has a different number than the second plurality. The first ends of the first and second tubes have substantially the same outside diameter and are abutted during connection so that an orifice is formed whenever first and second tube cavities substantially overlap. A rotation prevension element is placed in the orifice to prevent rotation of the first and second tubes. A collar with an internal threaded portion is slidably disposed about the second tube. The internal threaded portion engages the external threaded portion of the first tube to connect the tubes. A lip connected to the collar prevents separation of the collar from the second tube.

  19. Neural networks in seismic discrimination

    SciTech Connect

    Dowla, F.U.

    1995-01-01

    Neural networks are powerful and elegant computational tools that can be used in the analysis of geophysical signals. At Lawrence Livermore National Laboratory, we have developed neural networks to solve problems in seismic discrimination, event classification, and seismic and hydrodynamic yield estimation. Other researchers have used neural networks for seismic phase identification. We are currently developing neural networks to estimate depths of seismic events using regional seismograms. In this paper different types of network architecture and representation techniques are discussed. We address the important problem of designing neural networks with good generalization capabilities. Examples of neural networks for treaty verification applications are also described.

  20. Experimental study on thermal performance of filled-type evacuated tube with U-tube

    NASA Astrophysics Data System (ADS)

    Liang, Ruobing; Ma, Liangdong; Zhang, Jili; Zhao, Dan

    2012-06-01

    The filled-type evacuated tube with U-tube, in which the filled layer is used to transfer energy absorbed by working fluid in the U-tube, is proposed to eliminate the effect of thermal resistance between the absorber tube and copper fin of the conventional solar collector. In this paper, the thermal performance of the filled-type evacuated tube was researched by means of experimental study. In order to avoid the effect of some uncertain factors, the single collector tube was considered as investigated objective. The test setup of the thermal performance of the filled-type evacuated tube with U-tube was established. The results show that the filled-type evacuated tube with U-tube has a favorable thermal performance compared with the evacuated tube with copper fin. The heat efficiency of filled-type evacuated tube is higher than that of copper fin evacuated tube by 12%. The useful energy gain of filled-type evacuated tube is 22% higher than that of copper fin evacuated tube at the practical irradiance received I T = 800 W/m2 and flow rate M f = 0.005 L/s. In addition, the exergy efficiency of the filled-type evacuated tube is higher than that of copper fin evacuated tube.

  1. Conducting Polymers for Neural Prosthetic and Neural Interface Applications.

    PubMed

    Green, Rylie; Abidian, Mohammad Reza

    2015-12-01

    Neural-interfacing devices are an artificial mechanism for restoring or supplementing the function of the nervous system, lost as a result of injury or disease. Conducting polymers (CPs) are gaining significant attention due to their capacity to meet the performance criteria of a number of neuronal therapies including recording and stimulating neural activity, the regeneration of neural tissue and the delivery of bioactive molecules for mediating device-tissue interactions. CPs form a flexible platform technology that enables the development of tailored materials for a range of neuronal diagnostic and treatment therapies. In this review, the application of CPs for neural prostheses and other neural interfacing devices is discussed, with a specific focus on neural recording, neural stimulation, neural regeneration, and therapeutic drug delivery. PMID:26414302

  2. 21 CFR 874.3880 - Tympanostomy tube.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3880 Tympanostomy tube. (a) Identification... A tympanostomy tube is a device that is intended to be implanted for ventilation or drainage of the middle ear....

  3. 21 CFR 874.3880 - Tympanostomy tube.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3880 Tympanostomy tube. (a) Identification... A tympanostomy tube is a device that is intended to be implanted for ventilation or drainage of the middle ear....

  4. Fracture compliance estimation using borehole tube waves

    E-print Network

    Bakku, Sudhish Kumar

    We tested two models, one for tube-wave generation and the other for tube-wave attenuation at a fracture intersecting a borehole that can be used to estimate fracture compliance, fracture aperture, and lateral extent. In ...

  5. Performance of drift tubes under high radiation

    E-print Network

    Shi, Yue, S.B. Massachusetts Institute of Technology

    2005-01-01

    In this thesis, the aging and the rejuvenation of an ATLAS proportional drift tube are described. Firstly, the Diethorn model of gain is tested using pressure and sense-wire voltage measurements. The drift tube was then ...

  6. Reduce - and Report - Enteral Feeding Tube Misconnections

    MedlinePLUS

    ... patient requiring mechanical ventilation also had a nasogastric (NG) tube in place. After being transported to another ... high-flow oxygen was accidentally connected to the NG tube. The patient subsequently underwent emergency surgery to ...

  7. Two phase flow in capillary tubes

    E-print Network

    Suo, Mikio

    1963-01-01

    The flow of two phases, gas and liquid, has been studied in horizontal tubes of capillary diameter. The flow has been primarily studied in the regime where the gas flows as long bubbles separated from the wall of the tube ...

  8. Chemical recombination in an expansion tube

    NASA Technical Reports Server (NTRS)

    Bakos, Robert J.; Morgan, Richard G.

    1994-01-01

    The note describes the theoretical basis of chemical recombination in an expansion tube which simulates energy, Reynolds number, and stream chemistry at near-orbital velocities. Expansion tubes can satisfy ground-based hypersonic propulsion and aerothermal testing requirements.

  9. Magnetohydrostatic equilibrium. II. Three-dimensional multiple open magnetic flux tubes in the stratified solar atmosphere

    SciTech Connect

    Gent, F. A.; Erdélyi, R.; Fedun, V.

    2014-07-01

    A system of multiple open magnetic flux tubes spanning the solar photosphere and lower corona is modeled analytically, within a realistic stratified atmosphere subject to solar gravity. This extends results for a single magnetic flux tube in magnetohydrostatic equilibrium, described in Gent et al. Self-similar magnetic flux tubes are combined to form magnetic structures, which are consistent with high-resolution observations. The observational evidence supports the existence of strands of open flux tubes and loops persisting in a relatively steady state. Self-similar magnetic flux tubes, for which an analytic solution to the plasma density and pressure distribution is possible, are combined. We calculate the appropriate balancing forces, applying to the equations of momentum and energy conservation to preserve equilibrium. Multiplex flux tube configurations are observed to remain relatively stable for up to a day or more, and it is our aim to apply our model as the background condition for numerical studies of energy transport mechanisms from the solar surface to the corona. We apply magnetic field strength, plasma density, pressure, and temperature distributions consistent with observational and theoretical estimates for the lower solar atmosphere. Although each flux tube is identical in construction apart from the location of the radial axis, combinations can be applied to generate a non-axisymmetric magnetic field with multiple non-uniform flux tubes. This is a considerable step forward in modeling the realistic magnetized three-dimensional equilibria of the solar atmosphere.

  10. The cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Silk, Joseph

    1989-01-01

    Recent observational and theoretical investigations of the cosmic microwave background radiation (CMBR) are reviewed. Particular attention is given to spectral distortions and CMBR temperature anisotropies at large, intermediate, and small angular scales. The implications of the observations for inflationary cosmological models with curvature fluctuation are explored, and it is shown that the limits determined for intermediate-scale CMBR anisotropy almost rule out a baryon-dominated cosmology.

  11. Antiscalar cosmological background

    E-print Network

    Eduard G. Mychelkin; Maxim A. Makukov

    2015-06-11

    It is shown that the antiscalar approach to dark energy, whereby the energy-momentum tensor of the scalar field has the sign opposite to that of the rest of the matter, follows from the considerations of thermodynamic stability, as well as from the static limit of the Einstein-Maxwell equations. The same limit also demonstrates that the resulting background antiscalar field proves to be of quasi-electrostatic origin.

  12. Conceptual optimization using genetic algorithms for tube in tube structures

    SciTech Connect

    Pârv, Bianca Roxana; Hulea, Radu; Mojolic, Cristian

    2015-03-10

    The purpose of this article is to optimize the tube in tube structural systems for tall buildings under the horizontal wind loads. It is well-known that the horizontal wind loads is the main criteria when choosing the structural system, the types and the dimensions of structural elements in the majority of tall buildings. Thus, the structural response of tall buildings under the horizontal wind loads will be analyzed for 40 story buildings and a total height of 120 meters; the horizontal dimensions will be 30m × 30m for the first two optimization problems and 15m × 15m for the third. The optimization problems will have the following as objective function the cross section area, as restrictions the displacement of the building< the admissible displacement (H/500), and as variables the cross section dimensions of the structural elements.

  13. Fuzzy logic and neural network technologies

    NASA Technical Reports Server (NTRS)

    Villarreal, James A.; Lea, Robert N.; Savely, Robert T.

    1992-01-01

    Applications of fuzzy logic technologies in NASA projects are reviewed to examine their advantages in the development of neural networks for aerospace and commercial expert systems and control. Examples of fuzzy-logic applications include a 6-DOF spacecraft controller, collision-avoidance systems, and reinforcement-learning techniques. The commercial applications examined include a fuzzy autofocusing system, an air conditioning system, and an automobile transmission application. The practical use of fuzzy logic is set in the theoretical context of artificial neural systems (ANSs) to give the background for an overview of ANS research programs at NASA. The research and application programs include the Network Execution and Training Simulator and faster training algorithms such as the Difference Optimized Training Scheme. The networks are well suited for pattern-recognition applications such as predicting sunspots, controlling posture maintenance, and conducting adaptive diagnoses.

  14. 3D nano/microfabrication techniques and nanobiomaterials for neural tissue regeneration.

    PubMed

    Zhu, Wei; O'Brien, Christopher; O'Brien, Joseph R; Zhang, Lijie Grace

    2014-05-01

    Injuries of the nervous system occur commonly among people of many different ages and backgrounds. Currently, there are no effective strategies to improve neural regeneration; however, tissue engineering provides a promising avenue for regeneration of many tissue types, including the neural context. Functional nerve conduits derived from tissue engineering techniques present bioengineered 3D artificial substitutes for implantation and rehabilitation of injured nerves. In particular, nanotechnology as a versatile vehicle to create biomimetic nanostructured tissue-engineered neural scaffolds provides great potential for the development of innovative and successful nerve grafts. Nanostructured conduits derived from traditional and novel tissue engineering techniques have been shown to be superior for successful neural function construction due to a high degree of biomimetic character. In this paper, we will focus on current progress in developing 3D nano/microstructured neural scaffolds via electrospinning, emerging 3D printing and self-assembly techniques, nanobiomaterials and bioactive cues for enhanced neural tissue regeneration. PMID:24981651

  15. Diffusion Tubes for Ambient NO2 Monitoring

    E-print Network

    Short, Daniel

    Diffusion Tubes for Ambient NO2 Monitoring: Practical Guidance for Laboratories and Users Report to Defra and the Devolved Administrations ED48673043 Issue 1a Feb 2008 #12;Diffusion Tubes for Ambient NO2 Monitoring: Practical Guidance AEA/ENV/R/2504 ­ Issue 1a Title Diffusion Tubes for Ambient NO2 Monitoring

  16. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Impression tube. 872.6570 Section 872.6570 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... tube is a device consisting of a hollow copper tube intended to take an impression of a single...

  17. A Novel Mediastinal Drainage Tube for Mediastinitis

    PubMed Central

    Yhang, Jun Ho; Jang, In-Seok; Kim, Sung Hwan; Park, Hyun Ho; Kang, Dong Hoon; Choi, Jun Young

    2015-01-01

    Mediastinitis is a life-threatening disease, and effective drainage is needed to treat mediastinitis with abscess formation. We recommend an alternative drainage method using chest tube binding with a Silastic Penrose drainage tube. The use of a Silastic Penrose drainage tube may help to manage mediastinitis with abscess formation. This method facilitates effective draining and prevents tissue adhesion. PMID:26509136

  18. A Novel Mediastinal Drainage Tube for Mediastinitis.

    PubMed

    Yhang, Jun Ho; Jang, In-Seok; Kim, Sung Hwan; Park, Hyun Ho; Kang, Dong Hoon; Choi, Jun Young

    2015-10-01

    Mediastinitis is a life-threatening disease, and effective drainage is needed to treat mediastinitis with abscess formation. We recommend an alternative drainage method using chest tube binding with a Silastic Penrose drainage tube. The use of a Silastic Penrose drainage tube may help to manage mediastinitis with abscess formation. This method facilitates effective draining and prevents tissue adhesion. PMID:26509136

  19. Kundt's Tube: An Acoustic Gas Analyzer

    ERIC Educational Resources Information Center

    Aristov, Natasha; Habekost, Gehsa; Habekost, Achim

    2011-01-01

    A Kundt tube is normally used to measure the speed of sound in gases. Therefore, from known speeds of sound, a Kundt tube can be used to identify gases and their fractions in mixtures. In these experiments, the speed of sound is determined by measuring the frequency of a standing sound wave at a fixed tube length, temperature, and pressure. This…

  20. Cryogenic thermoelectric thermometer using a heat tube

    SciTech Connect

    Skripnik, Yu.A.; Khimicheva, A.I.

    1995-09-01

    An original application of heat tubes is proposed for increasing the accuracy of cryogenic temperature measurement. This is achieved by supplementary action on the working end of the thermocouple, based on the tube`s heat energy transmission, controlled by a magnetic field.

  1. Manual tube-to-tubesheet welding torch

    DOEpatents

    Kiefer, Joseph H. (Tampa, FL); Smith, Danny J. (Tampa, FL)

    1982-01-01

    A welding torch made of a high temperature plastic which fits over a tube intermediate the ends thereof for welding the juncture between the tube and the back side of a tube plate and has a ballooned end in which an electrode, filler wire guide, fiber optic bundle, and blanketing gas duct are disposed.

  2. 21 CFR 874.3880 - Tympanostomy tube.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3880 Tympanostomy tube. (a) Identification... middle ear. The device is inserted through the tympanic membrane to permit a free exchange of air between the outer ear and middle ear. A type of tympanostomy tube known as the malleous clip tube attaches...

  3. 21 CFR 874.3880 - Tympanostomy tube.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3880 Tympanostomy tube. (a) Identification... middle ear. The device is inserted through the tympanic membrane to permit a free exchange of air between the outer ear and middle ear. A type of tympanostomy tube known as the malleous clip tube attaches...

  4. 21 CFR 874.3880 - Tympanostomy tube.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3880 Tympanostomy tube. (a) Identification... middle ear. The device is inserted through the tympanic membrane to permit a free exchange of air between the outer ear and middle ear. A type of tympanostomy tube known as the malleous clip tube attaches...

  5. 21 CFR 874.3880 - Tympanostomy tube.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3880 Tympanostomy tube. (a) Identification... middle ear. The device is inserted through the tympanic membrane to permit a free exchange of air between the outer ear and middle ear. A type of tympanostomy tube known as the malleous clip tube attaches...

  6. 21 CFR 874.3880 - Tympanostomy tube.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3880 Tympanostomy tube. (a) Identification... middle ear. The device is inserted through the tympanic membrane to permit a free exchange of air between the outer ear and middle ear. A type of tympanostomy tube known as the malleous clip tube attaches...

  7. The Fuge Tube Diode Array Spectrophotometer

    ERIC Educational Resources Information Center

    Arneson, B. T.; Long, S. R.; Stewart, K. K.; Lagowski, J. J.

    2008-01-01

    We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in…

  8. SHORT-TUBE SUBCRITICAL FLOW Enerag Division

    E-print Network

    Oak Ridge National Laboratory

    water two phase critical flow [1-6]. In the air conditioning and refrigeration field, short tubes-tube subcritical flow. For short tubes used as refrigerant expansion devices, the orifice model is found inadequate/D) was not included. In this follow-up study, a separate correlation is formed so that the influence of L

  9. Spring/dimple instrument tube restraint

    DOEpatents

    DeMario, E.E.; Lawson, C.N.

    1993-11-23

    A nuclear fuel assembly for a pressurized water nuclear reactor has a spring and dimple structure formed in a non-radioactive insert tube placed in the top of a sensor receiving instrumentation tube thimble disposed in the fuel assembly and attached at a top nozzle, a bottom nozzle, and intermediate grids. The instrumentation tube thimble is open at the top, where the sensor or its connection extends through the cooling water for coupling to a sensor signal processor. The spring and dimple insert tube is mounted within the instrumentation tube thimble and extends downwardly adjacent the top. The springs and dimples restrain the sensor and its connections against lateral displacement causing impact with the instrumentation tube thimble due to the strong axial flow of cooling water. The instrumentation tube has a stainless steel outer sleeve and a zirconium alloy inner sleeve below the insert tube adjacent the top. The insert tube is relatively non-radioactivated inconel alloy. The opposed springs and dimples are formed on diametrically opposite inner walls of the insert tube, the springs being formed as spaced axial cuts in the insert tube, with a web of the insert tube between the cuts bowed radially inwardly for forming the spring, and the dimples being formed as radially inward protrusions opposed to the springs. 7 figures.

  10. Spring/dimple instrument tube restraint

    DOEpatents

    DeMario, Edmund E. (Columbia, SC); Lawson, Charles N. (Columbia, SC)

    1993-01-01

    A nuclear fuel assembly for a pressurized water nuclear reactor has a spring and dimple structure formed in a non-radioactive insert tube placed in the top of a sensor receiving instrumentation tube thimble disposed in the fuel assembly and attached at a top nozzle, a bottom nozzle, and intermediate grids. The instrumentation tube thimble is open at the top, where the sensor or its connection extends through the cooling water for coupling to a sensor signal processor. The spring and dimple insert tube is mounted within the instrumentation tube thimble and extends downwardly adjacent the top. The springs and dimples restrain the sensor and its connections against lateral displacement causing impact with the instrumentation tube thimble due to the strong axial flow of cooling water. The instrumentation tube has a stainless steel outer sleeve and a zirconium alloy inner sleeve below the insert tube adjacent the top. The insert tube is relatively non-radioactivated inconel alloy. The opposed springs and dimples are formed on diametrically opposite inner walls of the insert tube, the springs being formed as spaced axial cuts in the insert tube, with a web of the insert tube between the cuts bowed radially inwardly for forming the spring, and the dimples being formed as radially inward protrusions opposed to the springs.

  11. Supramolecular architectures for neural prostheses

    E-print Network

    Theogarajan, Luke Satish Kumar

    2007-01-01

    Neural prosthetic devices offer a means of restoring function that have been lost due to neural damage. The first part of this thesis investigates the design of a 15-channel, low-power, fully implantable stimulator chip. ...

  12. Fuzzy Multiresolution Neural Networks

    NASA Astrophysics Data System (ADS)

    Ying, Li; Qigang, Shang; Na, Lei

    A fuzzy multi-resolution neural network (FMRANN) based on particle swarm algorithm is proposed to approximate arbitrary nonlinear function. The active function of the FMRANN consists of not only the wavelet functions, but also the scaling functions, whose translation parameters and dilation parameters are adjustable. A set of fuzzy rules are involved in the FMRANN. Each rule either corresponding to a subset consists of scaling functions, or corresponding to a sub-wavelet neural network consists of wavelets with same dilation parameters. Incorporating the time-frequency localization and multi-resolution properties of wavelets with the ability of self-learning of fuzzy neural network, the approximation ability of FMRANN can be remarkable improved. A particle swarm algorithm is adopted to learn the translation and dilation parameters of the wavelets and adjusting the shape of membership functions. Simulation examples are presented to validate the effectiveness of FMRANN.

  13. The ''neural'' phonetic typewriter

    SciTech Connect

    Kohonen, T.

    1988-03-01

    Recently, researchers have placed great hopes on artificial neural networks to perform such ''natural'' tasks as speech recognition. This was indeed one motivation for us to start research in this area many years ago at Helsinki University of Technology. This article describes the result of that research - a complete ''neural'' speech recognition system, which recognizes phonetic units, called phonemes, from a continuous speech signal. Although motivated by neural network principles, the choices in design must be regarded as a compromise of many technical aspects of those principles. As our system is a genuine ''phonetic typewriter'' intended to transcribe orthographically edited text from an unlimited vocabulary, it cannot be directed compared with any more conventional, word-based system that applies classical concepts such as dynamic time warping and hidden Markov models.

  14. 21 CFR 888.4230 - Cement ventilation tube.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

  15. 21 CFR 888.4230 - Cement ventilation tube.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

  16. 21 CFR 888.4230 - Cement ventilation tube.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

  17. 21 CFR 888.4230 - Cement ventilation tube.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

  18. 21 CFR 888.4230 - Cement ventilation tube.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Cement ventilation tube. 888.4230 Section 888.4230...Surgical Devices § 888.4230 Cement ventilation tube. (a) Identification. A cement ventilation tube is a tube-like device...

  19. Dissociative States and Neural Complexity

    ERIC Educational Resources Information Center

    Bob, Petr; Svetlak, Miroslav

    2011-01-01

    Recent findings indicate that neural mechanisms of consciousness are related to integration of distributed neural assemblies. This neural integration is particularly vulnerable to past stressful experiences that can lead to disintegration and dissociation of consciousness. These findings suggest that dissociation could be described as a level of…

  20. Morphomechanics: Transforming Tubes into Organs

    PubMed Central

    Taber, Larry A.

    2014-01-01

    After decades focusing on the molecular and genetic aspects of organogenesis, researchers are showing renewed interest in the physical mechanisms that create organs. This review deals with the mechanical processes involved in constructing the heart and brain, concentrating primarily on cardiac looping, shaping of the primitive brain tube, and folding of the cerebral cortex. Recent studies suggest that differential growth drives large-scale shape changes in all three problems, causing the heart and brain tubes to bend and the cerebral cortex to buckle. Relatively local changes in form involve other mechanisms such as differential contraction. Understanding the mechanics of organogenesis is central to determining the link between genetics and the biophysical creation of form and structure. PMID:24791687

  1. Ionization tube simmer current circuit

    DOEpatents

    Steinkraus, Jr., Robert F. (Livermore, CA)

    1994-01-01

    A highly efficient flash lamp simmer current circuit utilizes a fifty percent duty cycle square wave pulse generator to pass a current over a current limiting inductor to a full wave rectifier. The DC output of the rectifier is then passed over a voltage smoothing capacitor through a reverse current blocking diode to a flash lamp tube to sustain ionization in the tube between discharges via a small simmer current. An alternate embodiment of the circuit combines the pulse generator and inductor in the form of an FET off line square wave generator with an impedance limited step up output transformer which is then applied to the full wave rectifier as before to yield a similar simmer current.

  2. Ionization tube simmer current circuit

    DOEpatents

    Steinkraus, R.F. Jr.

    1994-12-13

    A highly efficient flash lamp simmer current circuit utilizes a fifty percent duty cycle square wave pulse generator to pass a current over a current limiting inductor to a full wave rectifier. The DC output of the rectifier is then passed over a voltage smoothing capacitor through a reverse current blocking diode to a flash lamp tube to sustain ionization in the tube between discharges via a small simmer current. An alternate embodiment of the circuit combines the pulse generator and inductor in the form of an FET off line square wave generator with an impedance limited step up output transformer which is then applied to the full wave rectifier as before to yield a similar simmer current. 6 figures.

  3. Gated SIT vidicon streak tube

    SciTech Connect

    Dunbar, D.L.; Yates, G.J.; Black, J.P.

    1985-01-01

    A recently developed prototype streak tube designed to produce high gain and resolution by incorporating the streak and readout functions in one envelope thereby minimizing photon-to-change transformations and eliminating external coupling losses is presented. The tube is based upon a grid-gated Silicon-Intensified-Target Vidicon (SITV) with integral Focus Projection Scan (FPS) TV readout. Demagnifying electron optics (m=0.63) in the image section map the 40-mm-diameter photocathode image unto a 25-mm-diameter silicon target where gains greater than or equal to10/sup 3/ are achieved with only 10 KV accelerating voltage. This is compared with much lower gains (approx.50) at much higher voltages (approx.30 KV) reported for streak tubes using phosphor screens. Because SIT technology is well established means for electron imaging in vacuum, such fundamental problems as ''backside thinning'' required for electron imaging unto CCDs do not exist. The high spatial resolution (approx.30 lp/mm), variable scan formats, and high speed electrostatic deflection (250 mm/sup 2/ areas are routinely rastered with 256 scan lines in 1.6 ms) available from FPS readout add versatility not available in CCD devices. Theoretical gain and spatial resolution for this design (developed jointly by Los Alamos National Laboratory and General Electric Co.) are compared with similar calculations and measured data obtained for RCA 73435 streaks fiber optically coupled to (1) 25-mm-diameter SIT FPS vidicons and (2) 40-mm-diameter MCPTs (proximity-focused microchannel plate image intensifier tubes) fiber optically coupled to 18-mm-diameter Sb/sub 2/S/sub 3/ FPS vidicons. Sweep sensitivity, shutter ratio, and record lengths for nanosecond duration (20 to 200 ns) streak applications are discussed.

  4. High contrast cathode ray tube

    NASA Technical Reports Server (NTRS)

    Lisovicz, E. J.; Catlaw, T. G. (inventors)

    1971-01-01

    A layer of material is described, which contains fine grains of phosphor material stimulated by electrons to produce visible radiation. The layer, which also contains fine grains of cobalt oxide, is deposited on the glass screen of a cathode ray tube to provide high contrast, by absorbing most of the visible radiation which is directed to the layer through the screen, while not materially affecting the visible light which the phosphor material produces in response to the electron stimulation.

  5. Through tubing progressing cavity pump

    SciTech Connect

    Morgan, A.E.

    1986-06-03

    A method is described of installing a progressing cavity pump assembly within a well, the pump assembly being of the type having a stator, a helical rotor located in the stator and rotated by a string of sucker rods extending through tubing to the surface. The method consists of: securing a tubular seating member to a lower end of the tubing and lowering the tubing into the well; mounting a seating member on a lower end of the pump assembly; mounting a rotor nipple to the upper end of the stator and a drive rod to the upper end of the rotor, and providing the rotor nipple and drive rod with engaging means that allows a selected amount of vertical movement of the rotor with respect to the stator; connecting the upper end of the drive rod to the sucker rods; lowering the pump assembly into the tubing on the sucker rods until the seating member on the pump assembly contacts the tubular seating member; continuing to lower the sucker rods without rotation, moving the rotor downward with respect to the stator and forcing the seating members together with the weight of the sucker rods applied to the stator through the engaging means; then moving the sucker rods and the rotor a selected distance upward while the stator remains stationary to position the top of the rotor above the stator a selected distance; then connecting the sucker rods at the surface to a rotary power source and rotating the sucker rods to cause the pump to operate.

  6. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, Gordon E. (Albuquerque, NM)

    1998-01-01

    A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

  7. Induction and patterning of trunk and tail neural ectoderm by the homeobox gene eve1 in zebrafish embryos

    PubMed Central

    Cruz, Carlos; Maegawa, Shingo; Weinberg, Eric S.; Wilson, Stephen W.; Dawid, Igor B.; Kudoh, Tetsuhiro

    2010-01-01

    In vertebrates, Evx homeodomain transcription factor-encoding genes are expressed in the posterior region during embryonic development, and overexpression experiments have revealed roles in tail development in fish and frogs. We analyzed the molecular mechanisms of posterior neural development and axis formation regulated by eve1. We show that eve1 is involved in establishing trunk and tail neural ectoderm by two independent mechanisms: First, eve1 posteriorizes neural ectoderm via induction of aldh1a2, which encodes an enzyme that synthesizes retinoic acid; second, eve1 is involved in neural induction in the posterior ectoderm by attenuating BMP expression. Further, eve1 can restore trunk neural tube formation in the organizer-deficient ichabod ?/? mutant. We conclude that eve1 is crucial for the organization of the antero-posterior and dorso-ventral axis in the gastrula ectoderm and also has trunk- and tail-promoting activity. PMID:20142486

  8. Turbine nozzle stage having thermocouple guide tube

    DOEpatents

    Schotsch, Margaret Jones (Greer, SC); Kirkpatrick, Francis Lawrence (late of Galway, NY); Lapine, Eric Michael (Northwood, NH)

    2002-01-01

    A guide tube is fixed adjacent opposite ends in outer and inner covers of a nozzle stage segment. The guide tube is serpentine in shape between the outer and inner covers and extends through a nozzle vane. An insert is disposed in the nozzle vane and has apertures to accommodate serpentine portions of the guide tube. Cooling steam is also supplied through chambers of the insert on opposite sides of a central insert chamber containing the guide tube. The opposite ends of the guide tube are fixed to sleeves, in turn fixed to the outer and inner covers.

  9. Vangl-dependent planar cell polarity signalling is not required for neural crest migration in mammals

    PubMed Central

    Pryor, Sophie E.; Massa, Valentina; Savery, Dawn; Andre, Philipp; Yang, Yingzi; Greene, Nicholas D. E.; Copp, Andrew J.

    2014-01-01

    The role of planar cell polarity (PCP) signalling in neural crest (NC) development is unclear. The PCP dependence of NC cell migration has been reported in Xenopus and zebrafish, but NC migration has not been studied in mammalian PCP mutants. Vangl2Lp/Lp mouse embryos lack PCP signalling and undergo almost complete failure of neural tube closure. Here we show, however, that NC specification, migration and derivative formation occur normally in Vangl2Lp/Lp embryos. The gene family member Vangl1 was not expressed in NC nor ectopically expressed in Vangl2Lp/Lp embryos, and doubly homozygous Vangl1/Vangl2 mutants exhibited normal NC migration. Acute downregulation of Vangl2 in the NC lineage did not prevent NC migration. In vitro, Vangl2Lp/Lp neural tube explants generated emigrating NC cells, as in wild type. Hence, PCP signalling is not essential for NC migration in mammals, in contrast to its essential role in neural tube closure. PCP mutations are thus unlikely to mediate NC-related birth defects in humans. PMID:25038043

  10. Nested neural networks

    NASA Technical Reports Server (NTRS)

    Baram, Yoram

    1988-01-01

    Nested neural networks, consisting of small interconnected subnetworks, allow for the storage and retrieval of neural state patterns of different sizes. The subnetworks are naturally categorized by layers of corresponding to spatial frequencies in the pattern field. The storage capacity and the error correction capability of the subnetworks generally increase with the degree of connectivity between layers (the nesting degree). Storage of only few subpatterns in each subnetworks results in a vast storage capacity of patterns and subpatterns in the nested network, maintaining high stability and error correction capability.

  11. The Narrow Theta(1543)--A QCD Dilemma: Tube or Not Tube?

    E-print Network

    Casher, A; Casher, Aharon; Nussinov, Shmuel

    2004-01-01

    We argue that a width of less than MeV of the new Theta resonance is inconsistent with the observed ratio of resonance and background events in the various photon initiated experiments if the latter can be described by K, K*, etc., exchange. An evaluation of the Feynman diagrams which were believed to be relevant is presented and supports the general claim in the one case where a cross section has been given by the experimental group. More detailed arguments based on the flux tube model explaining the narrow widths and the apparent conflict with the production rates are presented. We predict narrow Tetra-quarks at mass ~ O(1-1.2 GeV) which the analysis of LEAR may have missed.

  12. Gastroenteric tube feeding: Techniques, problems and solutions

    PubMed Central

    Blumenstein, Irina; Shastri, Yogesh M; Stein, Jürgen

    2014-01-01

    Gastroenteric tube feeding plays a major role in the management of patients with poor voluntary intake, chronic neurological or mechanical dysphagia or gut dysfunction, and patients who are critically ill. However, despite the benefits and widespread use of enteral tube feeding, some patients experience complications. This review aims to discuss and compare current knowledge regarding the clinical application of enteral tube feeding, together with associated complications and special aspects. We conducted an extensive literature search on PubMed, Embase and Medline using index terms relating to enteral access, enteral feeding/nutrition, tube feeding, percutaneous endoscopic gastrostomy/jejunostomy, endoscopic nasoenteric tube, nasogastric tube, and refeeding syndrome. The literature showed common routes of enteral access to include nasoenteral tube, gastrostomy and jejunostomy, while complications fall into four major categories: mechanical, e.g., tube blockage or removal; gastrointestinal, e.g., diarrhea; infectious e.g., aspiration pneumonia, tube site infection; and metabolic, e.g., refeeding syndrome, hyperglycemia. Although the type and frequency of complications arising from tube feeding vary considerably according to the chosen access route, gastrointestinal complications are without doubt the most common. Complications associated with enteral tube feeding can be reduced by careful observance of guidelines, including those related to food composition, administration rate, portion size, food temperature and patient supervision. PMID:25024606

  13. Minimum wear tube support hole design

    DOEpatents

    Glatthorn, Raymond H. (St. Petersburg, FL)

    1986-01-01

    A minimum-wear through-bore (16) is defined within a heat exchanger tube support plate (14) so as to have an hourglass configuration as determined by means of a constant radiused surface curvature (18) as defined by means of an external radius (R3), wherein the surface (18) extends between the upper surface (20) and lower surface (22) of the tube support plate (14). When a heat exchange tube (12) is disposed within the tube support plate (14) so as to pass through the through-bore (16), the heat exchange tube (12) is always in contact with a smoothly curved or radiused portion of the through-bore surface (16) whereby unacceptably excessive wear upon the heat exchange tube (12), as normally developed by means of sharp edges, lands, ridges, or the like conventionally part of the tube support plates, is eliminated or substantially reduced.

  14. The dynamics of open precipitation tubes

    NASA Astrophysics Data System (ADS)

    Kaminker, V.; Maselko, J.; Pantaleone, J.

    2014-06-01

    When a flowing fluid is channeled by chemical or physical precipitation, then tubular structures form. These patterns are common in nature, however, there have been few quantitative studies of their formation. Here, we report measurements of the radius, length, and internal pressure, as functions of time and flow rate, for precipitation tubes growing in chemical gardens. Using these measurements we develop models for how single tubes grow and also for how multiple tubes interact with each other. In particular, when multiple tubes grow from the same source they compete for resources; short/wide tubes have less resistance to flow, and so consume more of the resources, "killing" the growth of long/narrow tubes. These tube interactions are described by an equation similar to an unstable logistic equation.

  15. Statistics of vortex tube properties in isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Pirozzoli, Sergio

    2008-11-01

    The vortex tubes of isotropic turbulence are statistically analyzed by means of a feature-extraction algorithm applied to DNS data at several value of the Taylor Reynolds number. It is found that the main geometric parameters of the vortices (radius, induced velocity, core vorticity) exhibit log-normal distributions, and very nearly collapse in terms of Kolmogorov units. Consistent with pevious studies, we have found that vortex tubes are special instances of the vorticity field associated with intensity stronger than the mean and local alignment of the vorticity vector, which subjected to the r.m.s background strain. Contrary to previous findings, however, we find that the vortex core radius and the local strain are nearly statistically independent, thus raising doubts on the relevance of vortex models based on stretched axi-symmetric vortices. The analysis of the azimuthal velocity profiles indicate scaling of the induced velocity similar to recent experimental findings, but very different from Burgers vortex model.

  16. Modeling Orifice Pulse Tube Coolers

    NASA Technical Reports Server (NTRS)

    Roach, Kittel P.; Roach, P. R.; Lee, J. M.; Kashani, A.; McCreight, Craig R. (Technical Monitor)

    1996-01-01

    We have developed a calculational model that treats all the components of an orifice pulse tube cooler. We base our analysis on 1-dimensional thermodynamic equations for the regenerator and we assume that all mass flows, pressure oscillations and temperature oscillations are small and sinusoidal. Non-linear pressure drop effects are included in the regenerator to account for finite pressure amplitude effects. The resulting mass flows and pressures are matched at the boundaries with the other components of the cooler: compressor, aftercooler, cold heat exchanger, pulse tube, hot heat exchanger, orifice and reservoir. The results of the calculation are oscillating pressures, mass flows and enthalpy flows in the main components of the cooler. By comparing with the calculations of other available models, we show that our model is very similar to REGEN 3 from NIST and DeltaE from Los Alamos National Lab. Our model is much easier to use than other available models because of its simple graphical interface and the fact that no guesses are required for the operating pressures or mass flows. In addition, the model only requires a few minutes of running time allowing many parameters to be optimized in a reasonable time. A version of the model is available for use over the World Wide Web at http://irtek.arc.nasa.gov. Future enhancements include adding a bypass orifice and including second order terms in steady mass streaming and steady heat transfer. A two-dimensional anelastic approximation of the fluid equations will be used as the basis for the latter analysis. Preliminary results are given in dimensionless numbers appropriate for oscillating compressible flows. The model shows how transverse heat transfer reduces enthalpy flow, particularly for small pulse tubes. The model also clearly shows mass recirculation in the open tube on the order of the tube length. They result from the higher order Reynolds stresses. An interesting result of the linearized approach is that the steady mass streaming does not affect the enthalpy flow at second order. The major effect of recirculating mass streaming is to increase transverse temperature gradients, which leads to higher entropy production and reduced efficiency.

  17. Developmental Outcomes after Early or Delayed Insertion of Tympanostomy Tubes

    PubMed Central

    Paradise, Jack L.; Campbell, Thomas F.; Dollaghan, Christine A.; Feldman, Heidi M.; Bernard, Beverly S.; Colborn, D. Kathleen; Rockette, Howard E.; Janosky, Janine E.; Pitcairn, Dayna L.; Kurs-Lasky, Marcia; Sabo, Diane L.; Smith, Clyde G.

    2005-01-01

    BACKGROUND To prevent later developmental impairments, myringotomy with the insertion of tympanostomy tubes has often been undertaken in young children who have persistent otitis media with effusion. We previously reported that prompt as compared with delayed insertion of tympanostomy tubes in children with persistent effusion who were younger than three years of age did not result in improved developmental outcomes at three or four years of age. However, the effect on the outcomes of school-age children is unknown. METHODS We enrolled 6350 healthy infants younger than 62 days of age and evaluated them regularly for middle-ear effusion. Before three years of age, 429 children with persistent middle-ear effusion were randomly assigned to have tympanostomy tubes inserted either promptly or up to nine months later if effusion persisted. We assessed developmental outcomes in 395 of these children at six years of age. RESULTS At six years of age, 85 percent of children in the early-treatment group and 41 percent in the delayed-treatment group had received tympanostomy tubes. There were no significant differences in mean (±SD) scores favoring early versus delayed treatment on any of 30 measures, including the Wechsler Full-Scale Intelligence Quotient (98±13 vs. 98±14); Number of Different Words test, a measure of word diversity (183±36 vs. 175±36); Percentage of Consonants Correct–Revised test, a measure of speech-sound production (96±2 vs. 96±3); the SCAN test, a measure of central auditory processing (95±15 vs. 96±14); and several measures of behavior and emotion. CONCLUSIONS In otherwise healthy children younger than three years of age who have persistent middle-ear effusion within the duration of effusion that we studied, prompt insertion of tympanostomy tubes does not improve developmental outcomes at six years of age. PMID:16093466

  18. Cosmic microwave background theory.

    PubMed

    Bond, J R

    1998-01-01

    A long-standing goal of theorists has been to constrain cosmological parameters that define the structure formation theory from cosmic microwave background (CMB) anisotropy experiments and large-scale structure (LSS) observations. The status and future promise of this enterprise is described. Current band-powers in -space are consistent with a DeltaT flat in frequency and broadly follow inflation-based expectations. That the levels are approximately (10(-5))2 provides strong support for the gravitational instability theory, while the Far Infrared Absolute Spectrophotometer (FIRAS) constraints on energy injection rule out cosmic explosions as a dominant source of LSS. Band-powers at 100 suggest that the universe could not have re-ionized too early. To get the LSS of Cosmic Background Explorer (COBE)-normalized fluctuations right provides encouraging support that the initial fluctuation spectrum was not far off the scale invariant form that inflation models prefer: e.g., for tilted Lambda cold dark matter sequences of fixed 13-Gyr age (with the Hubble constant H0 marginalized), ns = 1.17 +/- 0.3 for Differential Microwave Radiometer (DMR) only; 1.15 +/- 0.08 for DMR plus the SK95 experiment; 1.00 +/- 0.04 for DMR plus all smaller angle experiments; 1.00 +/- 0.05 when LSS constraints are included as well. The CMB alone currently gives weak constraints on Lambda and moderate constraints on Omegatot, but theoretical forecasts of future long duration balloon and satellite experiments are shown which predict percent-level accuracy among a large fraction of the 10+ parameters characterizing the cosmic structure formation theory, at least if it is an inflation variant. PMID:9419321

  19. Massively parallel neural computation

    E-print Network

    Fox, Paul James

    2013-03-12

    . Modelling the topology of a neural network using wiring that directly mirrors this topology is often limited to single-chip systems as extending this type of topology modelling to multiple chips requires more pins than can be implemented on a chip package...

  20. Neural Networks and Micromechanics

    NASA Astrophysics Data System (ADS)

    Kussul, Ernst; Baidyk, Tatiana; Wunsch, Donald C.

    The title of the book, "Neural Networks and Micromechanics," seems artificial. However, the scientific and technological developments in recent decades demonstrate a very close connection between the two different areas of neural networks and micromechanics. The purpose of this book is to demonstrate this connection. Some artificial intelligence (AI) methods, including neural networks, could be used to improve automation system performance in manufacturing processes. However, the implementation of these AI methods within industry is rather slow because of the high cost of conducting experiments using conventional manufacturing and AI systems. To lower the cost, we have developed special micromechanical equipment that is similar to conventional mechanical equipment but of much smaller size and therefore of lower cost. This equipment could be used to evaluate different AI methods in an easy and inexpensive way. The proved methods could be transferred to industry through appropriate scaling. In this book, we describe the prototypes of low cost microequipment for manufacturing processes and the implementation of some AI methods to increase precision, such as computer vision systems based on neural networks for microdevice assembly and genetic algorithms for microequipment characterization and the increase of microequipment precision.

  1. Hybrid digital signal processing and neural networks for automated diagnostics using NDE methods

    SciTech Connect

    Upadhyaya, B.R.; Yan, W.

    1993-11-01

    The primary purpose of the current research was to develop an integrated approach by combining information compression methods and artificial neural networks for the monitoring of plant components using nondestructive examination data. Specifically, data from eddy current inspection of heat exchanger tubing were utilized to evaluate this technology. The focus of the research was to develop and test various data compression methods (for eddy current data) and the performance of different neural network paradigms for defect classification and defect parameter estimation. Feedforward, fully-connected neural networks, that use the back-propagation algorithm for network training, were implemented for defect classification and defect parameter estimation using a modular network architecture. A large eddy current tube inspection database was acquired from the Metals and Ceramics Division of ORNL. These data were used to study the performance of artificial neural networks for defect type classification and for estimating defect parameters. A PC-based data preprocessing and display program was also developed as part of an expert system for data management and decision making. The results of the analysis showed that for effective (low-error) defect classification and estimation of parameters, it is necessary to identify proper feature vectors using different data representation methods. The integration of data compression and artificial neural networks for information processing was established as an effective technique for automation of diagnostics using nondestructive examination methods.

  2. Pulse tube cooler having 1/4 wavelength resonator tube instead of reservoir

    NASA Technical Reports Server (NTRS)

    Gedeon, David R. (Inventor)

    2008-01-01

    An improved pulse tube cooler having a resonator tube connected in place of a compliance volume or reservoir. The resonator tube has a length substantially equal to an integer multiple of 1/4 wavelength of an acoustic wave in the working gas within the resonator tube at its operating frequency, temperature and pressure. Preferably, the resonator tube is formed integrally with the inertance tube as a single, integral tube with a length approximately 1/2 of that wavelength. Also preferably, the integral tube is spaced outwardly from and coiled around the connection of the regenerator to the pulse tube at a cold region of the cooler and the turns of the coil are thermally bonded together to improve heat conduction through the coil.

  3. Pulse Tube Coolers with an Inertance Tube: Theory, Modeling and Practice

    NASA Technical Reports Server (NTRS)

    Roach, Pat R.; Kashani, Ali; McCreight, Craig R. (Technical Monitor)

    1997-01-01

    We have studied the advantages to be gained by replacing the conventional orifice of a pulse tube cooler by an inertance tube - a long thin tube that introduces the possibility for additional phase shift between pressure and mass flow in the pulse tube section. The case for the use of an inertance tube is most clearly made with an electrical analogy where the 'inductance' added by the inertance tube allows for optimal power transfer at the cold heat exchanger. Detailed modeling of a pulse tube system with an inertance tube confirms these advantages. Comparison between a laboratory cooler with an orifice and with an inertance tube will be presented and reasons wily it is difficult to realize all the expected gain will be given.

  4. Multi-tube arrangement for combustor and method of making the multi-tube arrangement

    SciTech Connect

    Ziminsky, Willy Steve

    2012-07-31

    A fuel injector tube includes a one piece, unitary, polygonal tube having an inlet end and an outlet end. The fuel injector tube further includes a fuel passage extending from the inlet end to the outlet end along a longitudinal axis of the polygonal tube, a plurality of air passages extending from the inlet end to the outlet end and surrounding the fuel passage, and a plurality of fuel holes. Each fuel hole connects an air passage with the fuel passage. The inlet end of the polygonal tube is formed into a fuel tube. A fuel injector includes a plurality of fuel injector tubes and a plate. The plurality of fuel tubes are connected to the plate adjacent the inlet ends of the plurality of fuel injector tubes.

  5. Neural dynamics based on the recognition of neural fingerprints

    PubMed Central

    Carrillo-Medina, José Luis; Latorre, Roberto

    2015-01-01

    Experimental evidence has revealed the existence of characteristic spiking features in different neural signals, e.g., individual neural signatures identifying the emitter or functional signatures characterizing specific tasks. These neural fingerprints may play a critical role in neural information processing, since they allow receptors to discriminate or contextualize incoming stimuli. This could be a powerful strategy for neural systems that greatly enhances the encoding and processing capacity of these networks. Nevertheless, the study of information processing based on the identification of specific neural fingerprints has attracted little attention. In this work, we study (i) the emerging collective dynamics of a network of neurons that communicate with each other by exchange of neural fingerprints and (ii) the influence of the network topology on the self-organizing properties within the network. Complex collective dynamics emerge in the network in the presence of stimuli. Predefined inputs, i.e., specific neural fingerprints, are detected and encoded into coexisting patterns of activity that propagate throughout the network with different spatial organization. The patterns evoked by a stimulus can survive after the stimulation is over, which provides memory mechanisms to the network. The results presented in this paper suggest that neural information processing based on neural fingerprints can be a plausible, flexible, and powerful strategy. PMID:25852531

  6. Glycoprotein composition along the pistil of Malus x domestica and the modulation of pollen tube growth

    PubMed Central

    2014-01-01

    Background The characteristics of pollen tube growth are not constant, but display distinct patterns of growth within the different tissues of the pistil. In the stigma, the growth rate is slow and autotrophic, whereas in the style, it is rapid and heterotrophic. Very little is known about the interactions between these distinct maternal tissues and the traversing pollen tube and the role of this interaction on the observed metabolism. In this work we characterise pollen tube growth in the apple flower and look for differences in glycoprotein epitope localization between two different maternal tissues, the stigma and the style. Results While immunocytochemically-detected arabinogalactan proteins were present at high levels in the stigma, they were not detected in the transmitting tissue of the style, where extensins were abundant. Whereas extensins remained at high levels in unpollinated pistils, they were no longer present in the style following pollen tube passage. Similarily, while abundant in unpollinated styles, insoluble polysaccharides such as ?-glucans, were depleted in pollinated pistils. Conclusions The switch from autotropic to heterotrophic pollen tube growth correlates spatially with a change of glycoprotein epitopes between the stigma and the style. The depletion of extensins and polysaccharides following pollen tube passage in the style suggest a possible contribution to the acceleration of heterotrophic pollen tube growth, which would imply an active contribution of female tissues on prezygotic male–female crosstalk. PMID:24387633

  7. Sensing system for detection and control of deposition on pendant tubes in recovery and power boilers

    DOEpatents

    Kychakoff, George; Afromowitz, Martin A; Hugle, Richard E

    2005-06-21

    A system for detection and control of deposition on pendant tubes in recovery and power boilers includes one or more deposit monitoring sensors operating in infrared regions and about 4 or 8.7 microns and directly producing images of the interior of the boiler. An image pre-processing circuit (95) in which a 2-D image formed by the video data input is captured, and includes a low pass filter for performing noise filtering of said video input. An image segmentation module (105) for separating the image of the recovery boiler interior into background, pendant tubes, and deposition. An image-understanding unit (115) matches derived regions to a 3-D model of said boiler. It derives a 3-D structure the deposition on pendant tubes in the boiler and provides the information about deposits to the plant distributed control system (130) for more efficient operation of the plant pendant tube cleaning and operating systems.

  8. Plasma ? scaling of anisotropic magnetic field fluctuations in the solar wind flux tube

    SciTech Connect

    Sarkar, Aveek; Bhattacharjee, Amitava; Ebrahimi, Fatima E-mail: amitava@princeton.edu

    2014-03-10

    Based on various observations, it has been suggested that at 1 AU, solar wind consists of 'spaghetti'-like magnetic field structures that have the magnetic topology of flux tubes. It is also observed that the plasma fluctuation spectra at 1 AU show a plasma ? dependence. Reconciling these two sets of observations and using the Invariance Principle, Bhattacharjee et al. suggested that the plasma inside every flux tube may become unstable with respect to pressure-driven instabilities and gives rise to fluctuation spectra that depend on the local plasma ?. The present work is the first direct numerical simulation of such a flux tube. We solve the full magnetohydrodynamic equations using the DEBS code and show that if the plasma inside the flux tube is driven unstable by spatial inhomogeneities in the background plasma pressure, the observed nature of the fluctuating power spectra agrees reasonably well with observations, as well as the analytical prediction of Bhattacharjee et al.

  9. Acoustic target detection and classification using neural networks

    NASA Technical Reports Server (NTRS)

    Robertson, James A.; Conlon, Mark

    1993-01-01

    A neural network approach to the classification of acoustic emissions of ground vehicles and helicopters is demonstrated. Data collected during the Joint Acoustic Propagation Experiment conducted in July of l991 at White Sands Missile Range, New Mexico was used to train a classifier to distinguish between the spectrums of a UH-1, M60, M1 and M114. An output node was also included that would recognize background (i.e. no target) data. Analysis revealed specific hidden nodes responding to the features input into the classifier. Initial results using the neural network were encouraging with high correct identification rates accompanied by high levels of confidence.

  10. Neural dynamic optimization for control systems.II. Theory.

    PubMed

    Seong, C Y; Widrow, B

    2001-01-01

    The paper presents neural dynamic optimization (NDO) as a method of optimal feedback control for nonlinear multi-input-multi-output (MIMO) systems. The main feature of NDO is that it enables neural networks to approximate the optimal feedback solution whose existence dynamic programming (DP) justifies, thereby reducing the complexities of computation and storage problems of the classical methods such as DP. This paper mainly describes the theory of NDO, while the two other companion papers of this topic explain the background for the development of NDO and demonstrate the method with several applications including control of autonomous vehicles and of a robot arm, respectively. PMID:18244816

  11. Investigation on the Inertance Tubes of Pulse Tube Cryocooler Without Reservoir

    NASA Astrophysics Data System (ADS)

    Liu, Y. J.; Yang, L. W.; Liang, J. T.; Hong, G. T.

    2010-04-01

    Phase angle is of vital importance for high-efficiency pulse tube cryocoolers (PTCs). Inertance tube as the main phase shifter is useful for the PTCs to obtain appropriate phase angle. Experiments of inertance tube without reservoir under variable frequency, variable length and diameter of inertance tube and variable pressure amplitude are investigated respectively. In addition, the authors used DeltaEC, a computer program to predict the performance of low-amplitude thermoacoustic engines, to simulate the effects of inertance tube without reservoir. According to the comparison of experiments and theoretical simulations, DeltaEC method is feasible and effective to direct and improve the design of inertance tubes.

  12. Microscopic tubes in igneous rocks

    NASA Technical Reports Server (NTRS)

    Richter, D.; Simmons, G.

    1977-01-01

    Microscopic tubes have been observed in several igneous rocks and may be quite common. They occur in single crystals and have either elliptical or circular cross-sections 1 to 5 microns in diameter and are ten to hundreds of microns long. Microtubes may be hollow or partially or completely filled with another phase, but are distinct from acicular crystals of accessory minerals such as rutile. Microtubes can form by at least three processes: (1) the partial annealing of microcracks, (2) the natural etching of dislocations, or (3) the primary inclusion of fluid material during crystal growth.

  13. Counter-driver shock tube

    NASA Astrophysics Data System (ADS)

    Tamba, T.; Nguyen, T. M.; Takeya, K.; Harasaki, T.; Iwakawa, A.; Sasoh, A.

    2015-11-01

    A "counter-driver" shock tube was developed. In this device, two counter drivers are actuated with an appropriate delay time to generate the interaction between a shock wave and a flow in the opposite direction which is induced by another shock wave. The conditions for the counter drivers can be set independently. Each driver is activated by a separate electrically controlled diaphragm rupture device, in which a pneumatic piston drives a rupture needle with a temporal jitter of better than 1.1 ms. Operation demonstrations were conducted to evaluate the practical performance.

  14. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, G.E.

    1998-03-10

    A cold cathode vacuum discharge tube, and method for making same, are disclosed with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 15 figs.

  15. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, G.E.

    1998-04-14

    A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 14 figs.

  16. Tubing bomb coal liquefaction technique

    SciTech Connect

    Maa, P.S.

    1984-04-01

    An experimental coal liquefaction test procedure is described in which coal, solvent and hydrogen are reacted in a small, agitated batch reactor (tubing bomb) that is rapidly heated in a sand bath. The reactor is quench-cooled, and solid and liquid reaction products are removed using cyclohexane as a wash medium. Conversion of coal to cyclohexane-soluble material is reproducible and correlates well with the conversion to 538 C minus boiling point liquids by larger scale process units. Details of the apparatus and experimental procedure are given. Experimental results for a bituminous, a subbituminous coal and a lignite are presented.

  17. A practical guide to neural nets

    SciTech Connect

    Nelson, M.M.; Illingworth, W.T.

    1991-01-01

    The concept of neural networks, their operation, and applications are reviewed. Topics discussed include definitions, terminology, and concepts of neural networks, the principal issues and problems addressed by neural network technology, recent developments in the field of artificial intelligence, characteristics and limitations of neural networks, and various neural network architectures. Other topics covered include the basic learning mechanisms of neural networks, examples of neural network applications, implementations of neural networks, some current problems in neural network research, and suggestions for future research. 126 refs.

  18. Biological aerosol background characterization

    NASA Astrophysics Data System (ADS)

    Blatny, Janet; Fountain, Augustus W., III

    2011-05-01

    To provide useful information during military operations, or as part of other security situations, a biological aerosol detector has to respond within seconds or minutes to an attack by virulent biological agents, and with low false alarms. Within this time frame, measuring virulence of a known microorganism is extremely difficult, especially if the microorganism is of unknown antigenic or nucleic acid properties. Measuring "live" characteristics of an organism directly is not generally an option, yet only viable organisms are potentially infectious. Fluorescence based instruments have been designed to optically determine if aerosol particles have viability characteristics. Still, such commercially available biological aerosol detection equipment needs to be improved for their use in military and civil applications. Air has an endogenous population of microorganisms that may interfere with alarm software technologies. To design robust algorithms, a comprehensive knowledge of the airborne biological background content is essential. For this reason, there is a need to study ambient live bacterial populations in as many locations as possible. Doing so will permit collection of data to define diverse biological characteristics that in turn can be used to fine tune alarm algorithms. To avoid false alarms, improving software technologies for biological detectors is a crucial feature requiring considerations of various parameters that can be applied to suppress alarm triggers. This NATO Task Group will aim for developing reference methods for monitoring biological aerosol characteristics to improve alarm algorithms for biological detection. Additionally, they will focus on developing reference standard methodology for monitoring biological aerosol characteristics to reduce false alarm rates.

  19. How to measure tracheostomy tube cuff pressure.

    PubMed

    Credland, Nicola

    2015-09-30

    Rationale and key points This article explores the process and principles of measuring tracheostomy tube cuff pressure and the associated evidence base. It discusses the indications for tracheostomy tube cuff pressure measurement and identifies potential complications associated with the procedure. ? Regular measurement of tracheostomy tube cuff pressure is essential to prevent complications associated with tracheostomy tube placement. ? Tracheostomy tube cuff pressure should be between 20mmHg and 25mmHg. Reflective activity Clinical skills articles can help update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: 1. How this article might change your practice when checking tracheostomy tube cuff pressure. 2. Positive elements of care delivery and those that could be enhanced. Subscribers can upload their reflective accounts at: rcni.com/portfolio . PMID:26419168

  20. Large diameter lasing tube cooling arrangement

    DOEpatents

    Hall, Jerome P. (Livermore, CA); Alger, Terry W. (Tracy, CA); Anderson, Andrew T. (Livermore, CA); Arnold, Phillip A. (Livermore, CA)

    2004-05-18

    A cooling structure (16) for use inside a ceramic cylindrical tube (11) of a metal vapor laser (10) to cool the plasma in the tube (11), the cooling structure (16) comprising a plurality of circular metal members (17, 31) and mounting members (18, 34) that position the metal members (17, 31) coaxially in the tube (11) to form an annular lasing volume, with the metal members (17, 31) being axially spaced from each other along the length of the tube (11) to prevent the metal members from shorting out the current flow through the plasma in the tube (11) and to provide spaces through which the heat from localized hot spots in the plasma may radiate to the other side of the tube (11).

  1. Large Diameter Lasing Tube Cooling Arrangement

    DOEpatents

    Hall, Jerome P.; Alger, Terry W.; Anderson, Andrew T.; Arnold, Philip A.

    2004-05-18

    A cooling structure (16) for use inside a ceramic cylindrical tube (11) of a metal vapor laser (10) to cool the plasma in the tube (11), the cooling structure (16) comprising a plurality of circular metal members (17,31) and mounting members (18, 34) that position the metal members (17,31) coaxially in the tube (11) to form an annular lasing volume, with the metal members (17, 31) being axially spaced from each other along the length of the tube (11) to prevent the metal members from shorting out the current flow through the plasma in the tube (11) and to provide spaces through which the heat from localized hot spots in the plasma may radiate to the other side of the tube (11).

  2. Tube support grid and spacer therefor

    DOEpatents

    Ringsmuth, Richard J. (Solano Beach, CA); Kaufman, Jay S. (Del Mar, CA)

    1986-01-01

    A tube support grid and spacers therefor provide radially inward preloading of heat exchange tubes to minimize stress upon base welds due to differential thermal expansion. The grid comprises a concentric series of rings and spacers with opposing concave sides for conforming to the tubes and V-shaped ends to provide resilient flexibility. The flexibility aids in assembly and in transmitting seismic vibrations from the tubes to a shroud. The tube support grid may be assembled in place to achieve the desired inwardly radial preloading of the heat exchange tubes. Tab and slot assembly further minimizes stresses in the system. The radii of the grid rings may be preselected to effect the desired radially inward preloading.

  3. Nursing administration of medication via enteral tubes in adults: a systematic review.

    PubMed

    Phillips, Nicole M; Nay, Rhonda

    2007-09-01

    Background? Enteral tubes are frequently inserted as part of medical treatment in a wide range of patient situations. Patients with an enteral tube are cared for by nurses in a variety of settings, including general and specialised acute care areas, aged care facilities and at home. Regardless of the setting, nurses have the primary responsibility for administering medication through enteral tubes. Medication administration via an enteral tube is a reasonably common nursing intervention that entails a number of skills, including preparing the medication, verifying the tube position, flushing the tube and assessing for potential complications. If medications are not given effectively through an enteral tube, harmful consequences may result leading to increased morbidity, for example, tube occlusion, diarrhoea and aspiration pneumonia. There are resultant costs for the health-care system related to possible increased length of stay and increased use of equipment. Presently what is considered to be best practice to give medications through enteral tubes is unknown. Objectives? The objective of this systematic review was to determine the best available evidence on which nursing interventions are effective in minimising the complications associated with the administration of medications via enteral tubes in adults. Nursing interventions and considerations related to medication administration included form of medication, verifying tube placement before administration, methods used to give medication, methods used to flush tubes, maintenance of tube patency and specific practices to prevent possible complications related to the administration of enteral medications. Search strategy? The following databases were searched for literature reported in English only: CINAHL, MEDLINE, The Cochrane Library, Current Contents/All Editions, EMBASE, Australasian Medical Index and PsychINFO. There was no date restriction applied. In addition, the reference lists of all included studies were scrutinised for other potentially relevant studies. Selection criteria? Systematic reviews of randomised controlled trials (RCTs) and RCTs that compared the effectiveness of nursing interventions and considerations used in the administration of medications via enteral tubes. Other research methods, such as non-randomised controlled trials, longitudinal studies, cohort and case control studies, were also included. Exclusion criteria included studies investigating drug-nutrient interactions or the bioavailability of specific medications. Data collection and analysis? Initial consideration of potential relevance to the review was carried out by the primary author (NP). Two reviewers independently assessed study eligibility for inclusion. A meta-analysis could not be undertaken, as there were no comparable RCTs identified. All data were presented in a narrative summary. Results? There is very limited evidence regarding the effectiveness of nursing interventions in minimising the complications associated with enteral tube medication administration in adults. The review highlights a lack of high quality research on many important nursing issues relating to enteral medication administration. There is huge scope for further research. Some of the evidence that was identified included that nurses should consider the use of liquid form medications as there may be fewer tube occlusions than with solid forms in nasoenteral tubes and silicone percutaneous endoscopic gastronomy tubes. Nurses may need to consider the sorbitol content of some liquid medications, for example, elixirs, as diarrhoea has been attributed to the sorbitol content of the elixir, not the drug itself. In addition, the use of 30?mL of water for irrigation when administering medications or flushing small-diameter nasoenteral tubes may reduce the number of tube occlusions. PMID:21631795

  4. Making Internal Molds Of Long, Curved Tubes

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1989-01-01

    Mold material carried to internal weld joint and removed after impression taken. Remotely operated device makes impression mold of interior surface of tube at weld joint. Mold provides indication of extent of mismatch between members at joint. Maneuvered to weld inspected through curved tube 3 in. in diameter by 50 in. long. Readily adapted to making molds to measure depth of corrosion in boiler tubes or other pipes.

  5. Preparation of nitrogen-doped carbon tubes

    DOEpatents

    Chung, Hoon Taek; Zelenay, Piotr

    2015-12-22

    A method for synthesizing nitrogen-doped carbon tubes involves preparing a solution of cyanamide and a suitable transition metal-containing salt in a solvent, evaporating the solvent to form a solid, and pyrolyzing the solid under an inert atmosphere under conditions suitable for the production of nitrogen-doped carbon tubes from the solid. Pyrolyzing for a shorter period of time followed by rapid cooling resulted in a tubes with a narrower average diameter.

  6. Hand-Operated Hydraulic Tube Expander

    NASA Technical Reports Server (NTRS)

    Hagan, David W.; Wolff, Edwin D.

    1995-01-01

    Hand-operated tool expands end portion of narrow metal or plastic tube to slightly larger diameter. Used on tubes with original inner diameters as small as 0.060 in. Includes replaceable tip comprising ferrule and tubular expansion sleeve sized for sliding fit into tube to be expanded. Expansion sleeve swells in response to internal hydraulic pressure generated by turning handle and thereby advancing piston.

  7. Discovery of the Microwave Background Cosmic microwave background radiation

    E-print Network

    Barnes, Joshua Edward

    Discovery of the Microwave Background Cosmic microwave background radiation Signals from the early universe, or pigeon droppings? #12;Microwave Background Radiation The spectrum is a near- perfect match of a time when the entire universe was a black body with a temperature T 3000 K. Very uniform microwave

  8. Tubing bomb coal liquefaction technique

    SciTech Connect

    Maa, P.S.; Neavel, R.C.; Vernon, L.W.

    1984-04-01

    An experimental coal liquefaction test procedure is described in which coal, solvent, and hydrogen are reacted in a small, agitated batch reactor (tubing bomb) that is rapidly heated in a sand bath. After completion of the desired reaction time, the reactor is quench-cooled, and solid and liquid reaction products are removed using cyclohexane as a wash medium. Conversion of coal to cyclohexane soluble material is reproducible and correlates well with the conversion to 538/sup 0/C (1000/sup 0/F) minus boiling point liquids obtained by larger scale process units. The principal data obtained with the tubing bomb technique are: hydrogen consumption (molecular hydrogen and hydrogen transferred from the solvent), gas make (H/sub 2/S, CO /SUB x/, and hydrocarbon gases), water make, liquid yields, solid residue (cyclohexane insolubles), and conversion. Details of the apparatus, experimental procedure, sample analysis procedures, and data workup are described. Experimental results for a bituminous, a subbituminous coal and a lignite are shown to illustrate the technique.

  9. The transcription factor chicken Scratch2 is expressed in a subset of early postmitotic neural progenitors.

    PubMed

    Vieceli, Felipe Monteleone; Simões-Costa, Marcos; Turri, José Antonio; Kanno, Tatiane; Bronner, Marianne; Yan, Chao Yun Irene

    2013-01-01

    Scratch proteins are members of the Snail superfamily which have been shown to regulate invertebrate neural development. However, in vertebrates, little is known about the function of Scratch or its relationship to other neural transcription factors. We report the cloning of chicken Scratch2 (cScrt2) and describe its expression pattern in the chick embryo from HH15 through HH29. cScrt2 was detected in cranial ganglia, the nasal placode and neural tube. At all stages examined, cScrt2 expression is only detected within a subregion of the intermediate zone of the neural tube. cScrt2 is also expressed in the developing dorsal root ganglia from HH22-23 onwards and becomes limited to its dorsal medial domain at HH29. phospho-Histone H3 and BrdU-labeling revealed that the cScrt2 expression domain is located immediately external to the proliferative region. In contrast, cScrt2 domain overlapped almost completely with that of the postmitotic neural transcription factor NeuroM/Ath3/NEUROD4. Together, these data define cScrt2-positive cells as a subset of immediately postmitotic neural progenitors. Previous data has shown that Scrt2 is a repressor of E-box-driven transcription whereas NeuroM is an E-box-transactivator. In light of these data, the co-localization detected here suggests that Scrt2 and NeuroM may have opposing roles during definition of neural subtypes. PMID:23570883

  10. Simplified Explosive Joining of Tubes to Fittings

    NASA Technical Reports Server (NTRS)

    Bement, L. J.; Bailey, J. W.; Perry, R.; Finch, M. S.

    1987-01-01

    Technique simplifies tube-to-fitting joining, as compared to fusion welding, and provides improvement on standard procedures used to join tubes explosively to tube fittings. Special tool inserted into tube to be joined. Tool allows strip of ribbon explosive to be placed right at joint. Ribbon explosive and mild detonating fuse allows use of smaller charge. Assembled tool storable, and process amenable to automation. Assembly of components, insertion of tool into weld site, and joining operation mechanized without human contact. Used to assemble components in nuclear reactors or in other environments hostile to humans.

  11. True Color Tube Borescope Inspection System

    Energy Science and Technology Software Center (ESTSC)

    1997-08-07

    The overall purpose of TCTBIS is to determine the quality of the inside surface of a tube. This is done by acquiring multiple images along the inside of a tube and converting these images into one unwrapped image of the inside of a tube. This resultant image is the same as if you had slit a tube length-wise, flattened it out, and then taken a picture of it. What is unique about this system ismore »that the picture is acquired in a non-destructive manner. TCTBIS also analyzes the unwrapped images for oxidation, foreign particles, and surface imperfections, scratches.« less

  12. Flow boiling inside enhanced heat transfer tubes

    SciTech Connect

    Xiang, G.M.; Hu, H.Y.; Peng, X.F.; Wang, B.X.

    1996-12-31

    A tube with longitudinal microchannels on the inside wall was developed to enhance flow boiling heat transfer. The experimental investigation was conducted to identify the flow boiling heat transfer performance of liquid through the enhanced tubes. The flow boiling heat transfer in the enhanced tubes is greatly intensified, especially for the fully-developed nucleate boiling regime. The heat transfer coefficient in microchanneled tubes with smaller diameter is increased with a magnitude of 170% compared with the identical smooth tubes. The geometric configuration of microchannels and tubes would have significant effect of the flow boiling inside microchanneled tubes. The heat transfer performance of the microchanneled tubes is as good as or even better than that of other existing enhanced tubes. Liquid-vapor phase change heat and mass transport phenomenon is frequently encountered in many practical applications, such as in chemical and petrochemical industry, power generation, air conditioning and refrigeration. Phase change heat exchangers and equipment, including evaporators, condenser and reboilers, are widely used in these cases.

  13. Enhanced Evaporation and Condensation in Tubes

    NASA Astrophysics Data System (ADS)

    Honda, Hiroshi

    A state-of-the-art review of enhanced evaporation and condensation in horizontal microfin tubes and micro-channels that are used for air-conditioning and refrigeration applications is presented. The review covers the effects of flow pattern and geometrical parameters of the tubes on the heat transfer performance. Attention is paid to the effect of surface tension which leads to enhanced evaporation and condensation in the microfin tubes and micro-channels. A review of prior efforts to develop empirical correlations of the heat transfer coefficient and theoretical models for evaporation and condensation in the horizontal microfin tubes and micro-channels is also presented.

  14. Growth of decorated carbon nano-tubes

    NASA Astrophysics Data System (ADS)

    Kurt, Ralph; Karimi, Ayatollah; Hoffmann, Volker

    2001-03-01

    Decomposition of methane in a nitrogen atmosphere using bias-enhanced hot filament chemical vapour deposition results in the growth of nitrogenated carbon tubes. Different shapes were formed ranging from spherical aggregates to twisted nano-tubes. All these structures were grown direct onto pure Si wafer. Glow discharge optical emission spectroscopy reveals the presence of tungsten carbide impurities at the interface. Graphitic sheets growing perpendicular to the tube axis typically cover the surface of each coiled tube. The observed morphology resembles a feather boa. From this an enhanced charge transfer in a composite is expected making the material interesting for high strength, lightweight applications.

  15. Eddy current measurement of tube element spacing

    DOEpatents

    Latham, Wayne Meredith (Forest, VA); Hancock, Jimmy Wade (Lynchburg, VA); Grut, Jayne Marie (Madison Heights, VA)

    1998-01-01

    A method of electromagnetically measuring the distance between adjacent tube elements in a heat exchanger. A cylindrical, high magnetic permeability ferrite slug is placed in the tube adjacent the spacing to be measured. A bobbin or annular coil type probe operated in the absolute mode is inserted into a second tube adjacent the spacing to be measured. From prior calibrations on the response of the eddy current coil, the signals from the coil, when sensing the presence of the ferrite slug, are used to determine the spacing between the tubes.

  16. The structure of photospheric flux tubes

    NASA Astrophysics Data System (ADS)

    Thomas, John H.

    Basic physical mechanisms for producing the observed intense magnetic flux tubes in the solar photosphere are reviewed. The mechanism of flux expulsion by convective cells can concentrate magnetic flux up to the equipartition field strength, which is only about 200 G at the solar surface for the observed granular convection. Other mechanisms that partially evacuate the flux tube are needed to produce further concentration of magnetic flux to the observed values of 1000-1500 G. Two such mechanisms are discussed: concentration by convective collapse of a vertical flux tube in the superadiabatic layer just below the solar surface, and concentration by a siphon flow in an arched, isolated flux tube.

  17. Mass Transport and Reactions in the Tube-in-Tube Reactor

    E-print Network

    Yang, Lu

    The tube-in-tube reactor is a convenient method for implementing gas/liquid reactions on the microscale, in which pressurized gas permeates through a Teflon AF-2400 membrane and reacts with substrates in liquid phase. Here ...

  18. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    Each time the boiler is washed, arch tubes and water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and thermic siphons shall thoroughly be cleaned, washed and inspected. (b)...

  19. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    Each time the boiler is washed, arch tubes and water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and thermic siphons shall thoroughly be cleaned, washed and inspected. (b)...

  20. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    Each time the boiler is washed, arch tubes and water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and thermic siphons shall thoroughly be cleaned, washed and inspected. (b)...

  1. 49 CFR 230.61 - Arch tubes, water bar tubes, circulators and thermic siphons.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    Each time the boiler is washed, arch tubes and water bar tubes shall thoroughly be cleaned mechanically, washed, and inspected. Circulators and thermic siphons shall thoroughly be cleaned, washed and inspected. (b)...

  2. Practical emotional neural networks.

    PubMed

    Lotfi, Ehsan; Akbarzadeh-T, M-R

    2014-11-01

    In this paper, we propose a limbic-based artificial emotional neural network (LiAENN) for a pattern recognition problem. LiAENN is a novel computational neural model of the emotional brain that models emotional situations such as anxiety and confidence in the learning process, the short paths, the forgetting processes, and inhibitory mechanisms of the emotional brain. In the model, the learning weights are adjusted by the proposed anxious confident decayed brain emotional learning rules (ACDBEL). In engineering applications, LiAENN is utilized in facial detection, and emotion recognition. According to the comparative results on ORL and Yale datasets, LiAENN shows a higher accuracy than other applied emotional networks such as brain emotional learning (BEL) and emotional back propagation (EmBP) based networks. PMID:25078111

  3. Neural network technologies

    NASA Technical Reports Server (NTRS)

    Villarreal, James A.

    1991-01-01

    A whole new arena of computer technologies is now beginning to form. Still in its infancy, neural network technology is a biologically inspired methodology which draws on nature's own cognitive processes. The Software Technology Branch has provided a software tool, Neural Execution and Training System (NETS), to industry, government, and academia to facilitate and expedite the use of this technology. NETS is written in the C programming language and can be executed on a variety of machines. Once a network has been debugged, NETS can produce a C source code which implements the network. This code can then be incorporated into other software systems. Described here are various software projects currently under development with NETS and the anticipated future enhancements to NETS and the technology.

  4. 77 FR 3497 - Light-Walled Rectangular Pipe and Tube From Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-24

    ... Procedure (19 CFR 207.2(f)). Background The Commission instituted this review on July 1, 2011 (76 FR 38691) and determined on October 4, 2011 that it would conduct an expedited review (76 FR 64105, October 17... Light-Walled Rectangular Pipe and Tube From Taiwan Determination On the basis of the record...

  5. Snail2 directly represses cadherin6B during epithelial-to-mesenchymal transitions of the neural crest

    PubMed Central

    Taneyhill, Lisa A.; Coles, Edward G.; Bronner-Fraser, Marianne

    2008-01-01

    The neural crest, a transient population of migratory cells, forms the craniofacial skeleton and peripheral nervous system, among other derivatives in vertebrate embryos. The transcriptional repressor Snail2 is thought to be crucial for the epithelial-to-mesenchymal transition (EMT) that promotes neural crest delamination from the neural tube; however, little is known about its downstream targets. To this end, we depleted avian Snail2 in the premigratory neural crest using morpholino antisense oligonucleotides and examined effects on potential targets by quantitative PCR. Several dorsal neural tube genes were upregulated by alleviating Snail2 repression; moreover, the cell adhesion molecule cadherin6B was derepressed within 30 minutes of blocking Snail2 translation. Examination of the chick cadherin6B genomic sequence reveals that the regulatory region contains three pairs of clustered E boxes, representing putative Snail2 binding sites. Furthermore, in vivo and in vitro biochemical analyses demonstrate that Snail2 directly binds to these sites and regulates cadherin6B transcription. These results are the first to describe a direct target of Snail2 repression in vivo and in the context of the EMT that characterizes neural crest development. PMID:17344227

  6. Integrable Background Geometries

    NASA Astrophysics Data System (ADS)

    Calderbank, David M. J.

    2014-03-01

    This work has its origins in an attempt to describe systematically the integrable geometries and gauge theories in dimensions one to four related to twistor theory. In each such dimension, there is a nondegenerate integrable geometric structure, governed by a nonlinear integrable differential equation, and each solution of this equation determines a background geometry on which, for any Lie group G, an integrable gauge theory is defined. In four dimensions, the geometry is selfdual conformal geometry and the gauge theory is selfdual Yang-Mills theory, while the lower-dimensional structures are nondegenerate (i.e., non-null) reductions of this. Any solution of the gauge theory on a k-dimensional geometry, such that the gauge group H acts transitively on an ?-manifold, determines a (k+?)-dimensional geometry (k+??4) fibering over the k-dimensional geometry with H as a structure group. In the case of an ?-dimensional group H acting on itself by the regular representation, all (k+?)-dimensional geometries with symmetry group H are locally obtained in this way. This framework unifies and extends known results about dimensional reductions of selfdual conformal geometry and the selfdual Yang-Mills equation, and provides a rich supply of constructive methods. In one dimension, generalized Nahm equations provide a uniform description of four pole isomonodromic deformation problems, and may be related to the {SU}(?) Toda and dKP equations via a hodograph transformation. In two dimensions, the {Diff}(S^1) Hitchin equation is shown to be equivalent to the hyperCR Einstein-Weyl equation, while the {SDiff}(?^2) Hitchin equation leads to a Euclidean analogue of Plebanski's heavenly equations. In three and four dimensions, the constructions of this paper help to organize the huge range of examples of Einstein-Weyl and selfdual spaces in the literature, as well as providing some new ! ones. The nondegenerate reductions have a long ancestry. More ! recently , degenerate or null reductions have attracted increased interest. Two of these reductions and their gauge theories (arguably, the two most significant) are also described.

  7. Neurally-mediated sincope.

    PubMed

    Can, I; Cytron, J; Jhanjee, R; Nguyen, J; Benditt, D G

    2009-08-01

    Syncope is a syndrome characterized by a relatively sudden, temporary and self-terminating loss of consciousness; the causes may vary, but they have in common a temporary inadequacy of cerebral nutrient flow, usually due to a fall in systemic arterial pressure. However, while syncope is a common problem, it is only one explanation for episodic transient loss of consciousness (TLOC). Consequently, diagnostic evaluation should start with a broad consideration of real or seemingly real TLOC. Among those patients in whom TLOC is deemed to be due to ''true syncope'', the focus may then reasonably turn to assessing the various possible causes; in this regard, the neurally-mediated syncope syndromes are among the most frequently encountered. There are three common variations: vasovagal syncope (often termed the ''common'' faint), carotid sinus syndrome, and the so-called ''situational faints''. Defining whether the cause is due to a neurally-mediated reflex relies heavily on careful history taking and selected testing (e.g., tilt-test, carotid massage). These steps are important. Despite the fact that neurally-mediated faints are usually relatively benign from a mortality perspective, they are nevertheless only infrequently an isolated event; neurally-mediated syncope tends to recur, and physical injury resulting from falls or accidents, diminished quality-of-life, and possible restriction from employment or avocation are real concerns. Consequently, defining the specific form and developing an effective treatment strategy are crucial. In every case the goal should be to determine the cause of syncope with sufficient confidence to provide patients and family members with a reliable assessment of prognosis, recurrence risk, and treatment options. PMID:19749682

  8. Artificial neural networks

    SciTech Connect

    Vemuri, V.

    1988-01-01

    This volume provides an introduction to the exciting field of artificial neural networks and their potential role in the emerging field of neurocomputing. Although the genesis of this subject can be traced back to the 1940s, the present interest is largely due to the recent developments in theoretical models, technologies, and algorithms. This volume is devoted to introductory and theoretical concepts, and the emphasis is on network architectures, learning, associative memories, with a glimpse of the application areas and implementation experiences.

  9. Analysis of Red Blood Cell Behavior in a Narrow Tube

    NASA Astrophysics Data System (ADS)

    Hosaka, Haruki; Omori, Toshihiro; Imai, Yohsuke; Yamaguchi, Takami; Ishikawa, Takuji

    2012-11-01

    Red Blood Cell (RBC) is a main component of blood accounting for 40 percent in volume, and enclosed by a twodimensional hyper elastic membrane. RBCs strongly influence rheological properties and mass transport of blood. The deformation of RBCs in capillary and at narrowing is also important in considering mechano-transduction of RBCs and hemolysis, though it has not been clarified in detail. Thus, in this study, we investigated the behavior of a RBC flowing in a narrow tube. To carry out the fluid-structure interaction analysis, we coupled a boundary element method to analyze the velocity of the internal and external fluid with a finite element method to analyze the deformation of the membrane. The boundary element method has good calculation accuracy and its computational cost is low because three-dimensional flow filed can be calculated by a two-dimensional computational mesh. The background flow in a tube is pressure-driven Poiseuille flow. Additionally, to reduce the computational time, we implemented massive parallel computation by using GPUs. The results show that the deformation of a RBC is strongly affected by the Capillary number, which is the ratio of viscous force to the elastic force, radius of the tube, and the initial orientation.

  10. Leakage of fluid around endotracheal tube cuffs: a cadaver study

    PubMed Central

    Lucius, Ralph; Ewald, Kristian

    2013-01-01

    Background The aim of the study was to evaluate the leakage of liquid past the cuffs of tracheal tubes in fresh frozen human heads. Methods Six truncated fresh frozen heads were used and intubated with 8.0 mm endotracheal tubes. The intracuff pressures tested were 30 and 100 cmH2O. Subsequently, 20 ml of each of two oral antiseptic rinses (0.2% chlorhexidine and octenidine [octenidol®, Schülke & Mayr GmbH, Norderstedt, Germany]) was applied for thirty seconds in the mouth. During the trial, leakage of the cuffs was examined. Results The sealing between the tracheal cuff and tracheal wall was leakage-proof for all tested intracuff pressures and all tested antiseptic rinses. However, approximately 5.6 ml and 1.8 ml leaked into the esophagus and remained as a cuff-puddle, respectively. Conclusions The sealing between an endotracheal tube cuff with an intracuff pressure of 30 cmH2O and the tracheal wall is leakage-proof during oral care with antiseptic rinsing. An increase of intracuff pressure to 100 cmH2O does not appear to be required. PMID:24363847

  11. Sunspots and the physics of magnetic flux tubes. V - Mutual hydrodynamic forces between neighboring tubes

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1979-01-01

    The mutual hydrodynamic forces between parallel cylinders in a moving fluid are illustrated through several formal examples. Parallel tubes in a uniform flow are attracted or repelled depending on whether they are side by side or one ahead of the other, respectively. A pulsating or undulating tube attracts all other neighboring tubes toward itself. These hydrodynamic effects suggest that the separate flux tubes beneath the sunspots exert significant attractive forces on each other.

  12. Adrenergic innervation of the developing chick heart: neural crest ablations to produce sympathetically aneural hearts

    SciTech Connect

    Kirby, M.; Stewart, D.

    1984-11-01

    Ablation of various regions of premigratory trunk neural crest which gives rise to the sympathetic trunks was used to remove sympathetic cardiac innervation. Neuronal uptake of (/sup 3/H)-norepinephrine was used as an index of neuronal development in the chick atrium. Following ablation of neural crest over somites 10-15 or 15-20, uptake was significantly decreased in the atrium at 16 and 17 days of development. Ablation of neural crest over somites 5-10 and 20-25 caused no decrease in (/sup 3/H)-norepinephrine uptake. Removal of neural crest over somites 5-25 or 10-20 caused approximately equal depletions of (/sup 3/H)-norepinephrine uptake in the atrium. Cardiac norepinephrine concentration was significantly depressed following ablation of neural crest over somites 5-25 but not over somites 10-20. Light-microscopic and histofluorescent preparations confirmed the absence of sympathetic trunks in the region of the normal origin of the sympathetic cardiac nerves following neural crest ablation over somites 10-20. The neural tube and dorsal root ganglia were damaged in the area of the neural-crest ablation; however, all of these structures were normal cranial and caudal to the lesioned area. Development of most of the embryos as well as the morphology of all of the hearts was normal following the lesion. These results indicate that it is possible to produce sympathetically aneural hearts by neural-crest ablation; however, sympathetic cardiac nerves account for an insignificant amount of cardiac norepinephrine.

  13. Aircraft System Identification Using Artificial Neural Networks

    E-print Network

    Valasek, John

    Aircraft System Identification Using Artificial Neural Networks Kenton Kirkpatrick Jim May Jr. John Meeting January 9, 2013 Compos Volatus #12;Overview Motivation System Identification Artificial Neural Networks 2 Artificial Neural Networks ANNSID Conclusions and Open Challenges #12;Motivation 3 #12

  14. Complexity Results on Learning by Neural Nets

    E-print Network

    Lin, Jyh-Han; Vitter, Jeffrey Scott

    1991-01-01

    We consider the computational complexity of learning by neural nets. We are inter- ested in how hard it is to design appropriate neural net architectures and to train neural nets for general and specialized learning tasks. Our main result shows...

  15. Pool boiling of R-114/oil mixtures from single tubes and tube bundles. Master's thesis

    SciTech Connect

    Murphy, T.J.

    1987-09-01

    An apparatus was designed, fabricated, and operated for the testing of horizontal tube bundles for boiling of R-114 with various concentrations of oil. Preliminary data were taken on the top tube in the bundle, with and without the other tubes in operation. Results showed up to a 37% increase in the boiling heat-transfer coefficient as a result of the favorable bundle effect. In a separate single-tube apparatus, three enhanced tubes were tested at a saturation temperature of 2.2 C with oil mass concentrations of 0, 1, 2, 3, 6 and 10%. The tubes were: 1) a finned tube with 1024 fins per meter, 2) a finned tube with 1575 fins per meter and 3) a Turbo-B tube. These tubes resulted in enhancement ratios in pure refrigerant of 2.8, 3.8 and 5.2, respectively, at a practical heat flux of 30 kW/sq. meter. With 3% oil, these ratios were decreased to 2.6, 3.5 and 5, while with 10% oil, these ratios were further reduced to 2.6, 3.2 and 4.7, respectively. Based on these results, the use of Turbo-B tubes is expected to result in significant savings in weight and size of evaporators over the finned tubes presently in use on board some naval vessels.

  16. Uptake of Nitroaromatic Compounds by Polymeric Tubing

    SciTech Connect

    BOUNKEUA, VIENGNGEUN; RODACY, PHILIP J.

    2001-04-01

    The type of polymeric material used in the manufacturing of tubing determines its strength, elasticity, and durability. Tubing made of polymeric material is commonly used for analytical work because it is readily available, inexpensive and can be relatively inert. Polymeric tubing is used in many sampling applications for explosive compounds. A major concern is the uptake of the explosive compounds into or onto the tubing during sampling. Because of the reactive nature of explosives, it is important that as little of the detectable explosive as possible is lost by tubing uptake. It is also important that nothing leaches out of the tubing to interfere with the detection of explosives. High Performance Liquid Chromatography (HPLC) is commonly used for the analysis of trace levels of explosive compounds in the range of parts per billion (ppb) to parts per million (ppm). This study attempts to determine which types of polymers are most conducive to sampling applications where large volumes of dilute explosive solutions are collected through a length of tubing for analysis. This was determined by analyzing the amount of explosive lost from solution per cm{sup 2} of tubing in solution. It was determined that tubing made of polyethylene, teflon, polypropylene, or KYNAR{reg_sign} is recommended for dilute trinitrotoluene (TNT) solution analyses. Tubing made of polypropylene, PHARMED{reg_sign}, KYNAR{reg_sign}, or polyethylene is recommended for analyses involving dilute explosive solutions of RDX. Tubing made from polyurethane, TYGON{reg_sign}, nylon, vinyl, gum rubber, or reinforced PVC are not recommended because they leach contaminants into solution that may interfere with HPLC analysis of explosive peaks.

  17. A Comparison of the Use of Binary Decision Trees and Neural Networks in Top Quark Detection

    E-print Network

    David Bowser-Chao; Debra L. Dzialo

    1992-09-04

    The use of neural networks for signal vs.~background discrimination in high-energy physics experiment has been investigated and has compared favorably with the efficiency of traditional kinematic cuts. Recent work in top quark identification produced a neural network that, for a given top quark mass, yielded a higher signal to background ratio in Monte Carlo simulation than a corresponding set of conventional cuts. In this article we discuss another pattern-recognition algorithm, the binary decision tree. We have applied a binary decision tree to top quark identification at the Tevatron and found it to be comparable in performance to the neural network. Furthermore, reservations about the "black box" nature of neural network discriminators do not apply to binary decision trees; a binary decision tree may be reduced to a set of kinematic cuts subject to conventional error analysis.

  18. Paramecium swimming in capillary tube

    NASA Astrophysics Data System (ADS)

    Jana, Saikat; Um, Soong Ho; Jung, Sunghwan

    2012-04-01

    Swimming organisms in their natural habitat need to navigate through a wide range of geometries and chemical environments. Interaction with boundaries in such situations is ubiquitous and can significantly modify the swimming characteristics of the organism when compared to ideal laboratory conditions. We study the different patterns of ciliary locomotion in glass capillaries of varying diameter and characterize the effect of the solid boundaries on the velocities of the organism. Experimental observations show that Paramecium executes helical trajectories that slowly transition to straight lines as the diameter of the capillary tubes decreases. We predict the swimming velocity in capillaries by modeling the system as a confined cylinder propagating longitudinal metachronal waves that create a finite pressure gradient. Comparing with experiments, we find that such pressure gradient considerations are necessary for modeling finite sized ciliary organisms in restrictive geometries.

  19. Cylinder Expansion in Polypropylene Tubes

    NASA Astrophysics Data System (ADS)

    Pemberton, Steven; Tappan, Bryce; Manner, Virginia

    2015-06-01

    Cylinder Expansion has long been the benchmark test used to establish an equation of state for any detonable energetic material. However, some new explosives have properties that prevent the use of the traditional copper-walled test; two such issues are materials whose detonations proceed more slowly than the acoustic velocity in the copper liner, and materials with failure diameters large enough to render copper testing prohibitively expensive. Results are presented for experiments conducted using a stoichiometric mixture of ammonium perchlorate and dodecane, a slow-detonating explosive. In copper walls inconsistent expansion was observed due to acoustic precursor waves within the wall. Additional testing was performed in polyethylene and polypropylene tubes to determine whether sufficient expansion could be observed, and satisfactory results were achieved with polypropylene. (96TW-2015-0001) Membership Pending.

  20. Estimation of the Thickness of Overlapping Materials by Using Neural Networks

    SciTech Connect

    Reen, N.; Tansel, I. N.; Chen, P.; Wang, X.; Inanc, F.; Kropas-Hughes, C.

    2005-04-09

    Backpropagation type artificial neural networks (ANN) were used to estimate the thickness of two overlapping materials by inspecting two X-ray images obtained at different x-ray tube voltage settings. Radiographic images of overlapping aluminum and brass wedges were simulated by using the X-ray radiography simulation program XRSIM. Simulated images were used for training and testing of the ANNs. The average estimation error was less than 4% and 7% on the training and test data respectively.

  1. Square tubing reduces cost of telescoping bridge crane hoist

    NASA Technical Reports Server (NTRS)

    Bernstein, G.; Graae, J.; Schraidt, J.

    1967-01-01

    Using standard square tubing in a telescoping arrangement reduces the cost of a bridge crane hoist. Because surface tolerances of square tubing need not be as accurate as the tubing used previously and because no spline is necessary, the square tubing is significantly less expensive than splined telescoping tubes.

  2. Local Thickening of Stainless Tube Considering Dimension Variation of the Cold Roll Formed Tube Billet

    NASA Astrophysics Data System (ADS)

    Sheu, Jinn-Jong; Yu, Cheng-Hsien

    2011-01-01

    A stud end consists of tube body and a flange in order to connect two tubes to form a long straight or angled pipe line. The flange is thicker than the tube body to strengthen the pipe connection. A thicker round hollow disk is usually welded to a straight tube to get the flange of the tube end and then machined to the specified dimension of the two-piece type stud end. A one-piece type stud end of tube proposed here is produced via the local thickening of tube end, flaring, and flange forging processes. The roundness of raw tube is not promised in the cold roll forming (CRF) process, which causes the inaccuracy of dimensions, wrinkling, and folding defects during the local thickening process of tube end. In this paper, a preform process was proposed to correct the dimension of the tube to be thickened. The CRF tube billets were measured and preformed to the required dimensions before thickening. The proposed preforming process was able to resize and control the dimensions and roundness of the tube billet to prevent irregular movement of billet. A three-staged punch profile was designed to prevent the folding defect during the thickening process. Experiments of resizing and thickening were carried out to verify the simulation results and the proposed punch profile design. The CAE simulations demonstrated the defects of folding are very sensitive to the dimension variation of tube billet. The experimental results of thickening process were in good agreement with the simulation predictions using the perfect (with preforming process) and the imperfect (original CRF) tube billets. The proposed pre-forming process and the punch profile designs were able to minimize the surface defects of tube local thickening.

  3. Teaching Shakespeare with YouTube

    ERIC Educational Resources Information Center

    Desmet, Christy

    2009-01-01

    YouTube, the video sharing website that allows viewers to upload video content ranging from cute dog tricks to rare rock videos, also supports a lively community devoted to the performance of Shakespeare and Shakespearean adaptations. YouTube is also a popular site for student producers of Shakespeare performances, parodies, and other artistic…

  4. Dialyzers and D-Tube Electroelution Kit

    E-print Network

    Lebendiker, Mario

    such as dialysis and electro- elution (for extraction from gels) have long been used to purify proteins and nucleic of urea and detergents · One-step dialysis procedure that does not require syringes or any special-TubeTM Dialyzers are easy-to-handle dialyzers in a capped centrifuge tube format with dialysis membrane windows

  5. Places to Go: YouTube

    ERIC Educational Resources Information Center

    Downes, Stephen

    2008-01-01

    Founded in 2005 by three former PayPal employees, YouTube has revolutionized the Internet, marking a change from the static Internet to the dynamic Internet. In this edition of Places to Go, Stephen Downes discusses how the rise of a ubiquitous media format--Flash video--has made YouTube's success possible and argues that Flash video has important…

  6. www.elsevierhealth.com/journals/tube Tuberculosis

    E-print Network

    Sergot, Marek

    www.elsevierhealth.com/journals/tube Tuberculosis Visualization of microarray results to assist on Mycobacterium tuberculosis were used to develop and evaluate the visualization tool and initiate the development. All rights reserved. doi:10.1016/j.tube.2003.12.012 Tuberculosis (2004) 84, 275­281 #12;define

  7. Microphone Detects Boiler-Tube Leaks

    NASA Technical Reports Server (NTRS)

    Parthasarathy, S. P.

    1985-01-01

    Unit simple, sensitive, rugged, and reliable. Diaphragmless microphone detects leaks from small boiler tubes. Porous plug retains carbon granules in tube while allowing pressure changes to penetrate to granules. Has greater life expectancy than previous controllers and used in variety of hot corrosive atmospheres.

  8. Making Glass-Fiber-Reinforced Coolant Tubes

    NASA Technical Reports Server (NTRS)

    Curtin, F.

    1985-01-01

    New use found for heat-shrinkable sleeves. Smooth, noncontaminating channels for transporting cooling water in Space Shuttle Extravehicularmobility unit made of fiberglass tubing with aid of heat-shrinkable sleeves. Previously, glass fibers from inner walls of tubes contaminate water.

  9. Shrinking plastic tubing and nonstandard diameters

    NASA Technical Reports Server (NTRS)

    Ruiz, W. V.; Thatcher, C. S.

    1980-01-01

    Process allows larger-than-normal postshrink diameters without splitting. Tetrafluoroethylene tubing on mandrel is supported within hot steel pipe by several small diameter coil sections. Rising temperature of mandrel is measured via thermocouple so assembly can be removed without overshrinking (and splitting) of tubing.

  10. Winning the fight against boiler tube failure

    SciTech Connect

    Cohen, J.; Dooley, B.

    1986-12-01

    Eliminating boiler tube failures could be worth $5 billion a year to the electric power industry. The causes and cures for the great majority of these ubiquitous failures are now known, with implications for change ranging from senior management to the maintenance crew. Methods for preventing boiler tube failure are discussed.

  11. Telescoping of instrumentation tubing eliminates swaging

    NASA Technical Reports Server (NTRS)

    Mc Clellan, E. L.

    1966-01-01

    Short sections of stainless steel tubing of slide-fit sizes fitted together and silver-soldered at the junctions form small-diameter tubing assemblies with accurately stepped-down dimensions. This method of fabrication eliminates the costly swaging operations formerly used.

  12. Asymmetric -tube Support Vector Regression Xiaolin Huanga,

    E-print Network

    Regression (-SVR) has become a standard tool in nonparametric regression tasks. The -SVRs extend standardAsymmetric -tube Support Vector Regression Xiaolin Huanga, , Lei Shia,c , Kristiaan Pelckmansb-known -tube Support Vector Regression (-SVR) is an effective method for implementing this idea in the context

  13. Lox Separation Studies Using Cryogenic Vortex Tube

    NASA Astrophysics Data System (ADS)

    Jacob, S.; Paul, P. J.; Karunanithi, R.; Behera, Upendra

    2008-03-01

    In-flight collection of air, pre-cooling, liquefaction and separation of liquid oxygen (LOX) are key technologies for futuristic launch vehicles. Vortex tube technology is one of the few potential technologies for this application. Extensive studies have been carried out on straight and conical vortex tubes for developing vortex tube technology for high purity LOX separation. Studies show that 12mm diameter conical vortex tube with L&D of 10 could achieve LOX purity of ˜96% with separation efficiency of ˜14% indicating that it is not possible to obtain both high LOX purity and high separation efficiency simultaneously in a single vortex tube. However, it is possible to achieve both high LOX purity and separation efficiency by staging of vortex tubes. LOX purity of 96% and separation efficiency of ˜73.5% has been achieved for second stage vortex tube supplied with pre-cooled air having 60% oxygen purity. LOX purity has been further increased to 97% by applying controlled heating power over liquid oxygen flowing discharge surface of the vortex tube.

  14. Sampling Artifacts from Conductive Silicone Tubing

    SciTech Connect

    Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse; Jayne, John T.; Worsnop, Douglas R.; Miake-Lye, Richard C.; Onasch, Timothy B.; Liscinsky, David; Kirchstetter, Thomas W.; Destaillats, Hugo; Holder, Amara L.; Smith, Jared D.; Wilson, Kevin R.

    2009-05-15

    We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: 1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and 2) silicone tubing emits organic contaminants containing siloxane that adsorb onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosol mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and should, therefore, be used with caution. Gentle heating, physical and chemical properties of the particle carriers, exposure to solvents, and tubing age may influence siloxane uptake. The amount of contamination is expected to increase as the tubing surface area increases and as the particle surface area increases. The effect is observed at ambient temperature and enhanced by mild heating (<100 oC). Further evaluation is warranted.

  15. Neural Pascal A Language for Neural Network Programming

    E-print Network

    Gumm, H. Peter

    Neural Pascal A Language for Neural Network Programming H.Peter Gumm Dept. of Computer Science SUNY. On the other hand we did not want to design a new language from scratch but rather extend a widely used. Syntactically, just a handful of extensions to Pascal had to be added. Mainly they are syntax

  16. Incremental evolution of the neural crest, neural crest cells and neural crest-derived skeletal tissues

    PubMed Central

    Hall, Brian K; Gillis, J Andrew

    2013-01-01

    Urochordates (ascidians) have recently supplanted cephalochordates (amphioxus) as the extant sister taxon of vertebrates. Given that urochordates possess migratory cells that have been classified as ‘neural crest-like’– and that cephalochordates lack such cells – this phylogenetic hypothesis may have significant implications with respect to the origin of the neural crest and neural crest-derived skeletal tissues in vertebrates. We present an overview of the genes and gene regulatory network associated with specification of the neural crest in vertebrates. We then use these molecular data – alongside cell behaviour, cell fate and embryonic context – to assess putative antecedents (latent homologues) of the neural crest or neural crest cells in ascidians and cephalochordates. Ascidian migratory mesenchymal cells – non-pigment-forming trunk lateral line cells and pigment-forming ‘neural crest-like cells’ (NCLC) – are unlikely latent neural crest cell homologues. Rather, Snail-expressing cells at the neural plate of border of urochordates and cephalochordates likely represent the extent of neural crest elaboration in non-vertebrate chordates. We also review evidence for the evolutionary origin of two neural crest-derived skeletal tissues – cartilage and dentine. Dentine is a bona fide vertebrate novelty, and dentine-secreting odontoblasts represent a cell type that is exclusively derived from the neural crest. Cartilage, on the other hand, likely has a much deeper origin within the Metazoa. The mesodermally derived cellular cartilages of some protostome invertebrates are much more similar to vertebrate cartilage than is the acellular ‘cartilage-like’ tissue in cephalochordate pharyngeal arches. Cartilage, therefore, is not a vertebrate novelty, and a well-developed chondrogenic program was most likely co-opted from mesoderm to the neural crest along the vertebrate stem. We conclude that the neural crest is a vertebrate novelty, but that neural crest cells and their derivatives evolved and diversified in a step-wise fashion – first by elaboration of neural plate border cells, then by the innovation or co-option of new or ancient metazoan cell fates. PMID:22414251

  17. Eddy Current Inspection of INCONEL-600 Steam Generator Tubes at the Tube Sheet

    SciTech Connect

    Morris, C. J.; Lyon, G. H.; Davis, T. J.; Perry, C. B.

    1980-11-01

    The ability of eddy current inspection to detect and size flaws in Inconel 600 steam generator tubing at the tube sheet was studied. Single frequency absolute, single frequency differential, and multi-frequency differential eddy current tests were conducted on small, medium, and large volume defects placed into a simulated tube sheet. Position of each defect was varied with respect to the surface of the tube sheet. Results are presented on detectability and sizing of the defects versus measurement method, location of the defect relative to the tube sheet surface, and defect volume.

  18. A primer on draft tube surging

    SciTech Connect

    Falvey, H.T. )

    1993-02-01

    The draft tube surge is a significant factor to consider when operating hydropower plants at other than the maximum efficiency point. The magnitude of the surge and its effect on the electrical and hydraulic systems can be predicted by combining model investigations with a mathematical model that incorporates the system characteristics. Multiple vortices and multiple mode shapes complicate the prediction of the draft tube surge characteristics. The transition from one mode shape to another is a function of the swirl in the draft tube. The transition between mode shapes often produces large pressure pulses. Air injection and appurtenances in the draft tube throat can be effective in ameliorating the effects of the draft tube surge. However, these modifications frequently have adverse side effects, such as reduced efficiency of the turbine, and may not function properly at both part load and full load conditions.

  19. Ultra-fast framing camera tube

    DOEpatents

    Kalibjian, Ralph (1051 Batavia Ave., Livermore, CA 94550)

    1981-01-01

    An electronic framing camera tube features focal plane image dissection and synchronized restoration of the dissected electron line images to form two-dimensional framed images. Ultra-fast framing is performed by first streaking a two-dimensional electron image across a narrow slit, thereby dissecting the two-dimensional electron image into sequential electron line images. The dissected electron line images are then restored into a framed image by a restorer deflector operated synchronously with the dissector deflector. The number of framed images on the tube's viewing screen is equal to the number of dissecting slits in the tube. The distinguishing features of this ultra-fast framing camera tube are the focal plane dissecting slits, and the synchronously-operated restorer deflector which restores the dissected electron line images into a two-dimensional framed image. The framing camera tube can produce image frames having high spatial resolution of optical events in the sub-100 picosecond range.

  20. Pneumothorax occurring after nasogastric tube removal

    PubMed Central

    Paul, Vishesh; Shenoy, Amith; Kupfer, Yizhak; Tessler, Sidney

    2013-01-01

    An 85-year-old woman with failure to thrive due to poor oral intake was admitted owing to dehydration. A nasogastric (NG) tube was inserted for the initiation of enteral feedings. The tube position was confirmed by gastric auscultation after insufflating air through the tube. A chest X-ray revealed that the NG tube traversed the right main stem bronchus with its tip ending in the right costophrenic angle adjacent to the pleura. No pneumothorax was identified. The tube was removed and a short while later the patient developed mild chest discomfort. A repeat chest X-ray revealed significant pneumothorax on the right side. She was treated conservatively with 100% oxygen with successful resolution of the pneumothorax. PMID:24296770

  1. Torsional Kinematic Model for Concentric Tube Robots

    PubMed Central

    Dupont, Pierre E.; Lock, Jesse; Butler, Evan

    2011-01-01

    A recent approach to steerable needle design is based on combining pre-curved tubes concentrically. By rotating and extending the tubes with respect to each other, the position and orientation of the needle tip, as well as the shape of the inserted length, can be controlled. Prior models neglected torsional twisting in the curved portions of the tubes. This paper presents a mechanics model that includes torsion, applies to any number of tubes and allows curvature and stiffness to vary with arc length. While the general model is comprised of differential equations, an analytic solution is given for two tubes of constant curvature. This solution enables analytic prediction of “snap through” instability based on a single dimensionless parameter. Simulation and experiments are used to illustrate the results. PMID:21479158

  2. Simulation of Noise in a Traveling Wave Tube

    NASA Astrophysics Data System (ADS)

    Verboncoeur, J. P.; Christenson, P. J.; Smith, H. B.

    1999-11-01

    Low frequency noise, manifested as close-in sidebands, has long been a significant limit to the performance of many traveling wave tubes. In this study, we investigate oscillations in the gun region due to the presence of plasma formed by electron-impact ionization of a background gas. The gun region of a coupled-cavity traveling wave tube is modeled using the two-dimensional XOOPIC particle-in-cell Monte Carlo collision code (J. P. Verboncoeur et al. Comput. Phys. Comm.) 87, 199-211 (1995). (available via the web: http://ptsg.eecs.berkeley.edu). The beam is 20.5 kV, 2.8 A, in near-confined flow in a solenoidal magnetic field with peak axial value of 0.263 T. Beam scalloping leads to trapping of plasma generated via electron-impact ionization of a background gas. The trapped plasma periodically leaves the system rapidly, and the density begins regenerating at a slow rate, leading to characteristic sawtooth oscillations. Plasma electrons are observed to exit the system axially about 20 ns before the ions exit primarily radially.

  3. Cold Inertance Tube for 4 K Stirling Type Pulse Tube Cryocoolers

    NASA Astrophysics Data System (ADS)

    Li, ZhuoPei; Gan, ZhiHua; Qiu, LiMin

    The losses in the regenerator are minimized when the amplitude of the mass flow is minimized for a given acoustic power which requires that the mass flow lags the pressure by about 30° at the cold end of regenerator. The phase shift provided by an inertance tube is strongly influenced by the temperature of the inertance tube and the acoustic power at the cold end of the regenerator. For a 4 K Stirling type pulse tube cryocooler, the acoustic power at the cold end of the regenerator decreases significantly with the temperature thereby it's difficult to achieve ideal phase relationship with ambient inertance tube. While cold inertance tube provide a larger phase shift in that the viscosity of the working fluid decreases and the density increases as the temperature decreases. However, use of cold inertance tube increases additional heat load to the regenerator. Therefore it's of great significance to determine when a cold inertance tube should be used. In this paper effect of temperature of inertance tube is calculated for a 4 K Stirling type pulse tube cryocooler with different acoustic powers at the cold end. A comparison of ambient temperature inertance tube and cold inertance tube is made.

  4. Cyborg Bugs... and Neural Dust

    E-print Network

    Zakhor, Avideh

    system Seo D, et al. "Neural Dust: An Ultrasonic, Low Power SoluNon for ChronicNon of Untethered, Ultrasonic Neural Dust Motes for CorNcal Recording," submiEed #12;Basic/resoluNon to interrogate each mote · each mote consists of a piezoelectric transducer, surface

  5. Space-Time Neural Networks

    NASA Technical Reports Server (NTRS)

    Villarreal, James A.; Shelton, Robert O.

    1992-01-01

    Concept of space-time neural network affords distributed temporal memory enabling such network to model complicated dynamical systems mathematically and to recognize temporally varying spatial patterns. Digital filters replace synaptic-connection weights of conventional back-error-propagation neural network.

  6. Neural network applications in telecommunications

    NASA Technical Reports Server (NTRS)

    Alspector, Joshua

    1994-01-01

    Neural network capabilities include automatic and organized handling of complex information, quick adaptation to continuously changing environments, nonlinear modeling, and parallel implementation. This viewgraph presentation presents Bellcore work on applications, learning chip computational function, learning system block diagram, neural network equalization, broadband access control, calling-card fraud detection, software reliability prediction, and conclusions.

  7. Fluoroscopy-guided jejunal extension tube placement through existing gastrostomy tubes: analysis of 391 procedures

    PubMed Central

    Uflacker, Andre; Qiao, Yujie; Easley, Genevieve; Patrie, James; Lambert, Drew; de Lange, Eduard E.

    2015-01-01

    PURPOSE We aimed to evaluate the safety and efficacy of fluoroscopically placed jejunal extension tubes (J-arm) in patients with existing gastrostomy tubes. METHODS We conducted a retrospective review of 391 J-arm placements performed in 174 patients. Indications for jejunal nutrition were aspiration risk (35%), pancreatitis (17%), gastroparesis (13%), gastric outlet obstruction (12%), and other (23%). Technical success, complications, malfunctions, and patency were assessed. Percutaneous gastrostomy (PEG) tube location, J-arm course, and fluoroscopy time were correlated with success/failure. Failure was defined as inability to exit the stomach. Procedure-related complications were defined as adverse events related to tube placement occurring within seven days. Tube malfunctions and aspiration events were recorded and assessed. RESULTS Technical success was achieved in 91.9% (95% CI, 86.7%–95.2%) of new tubes versus 94.2% (95% CI, 86.7%–95.2%) of replacements (P = 0.373). Periprocedural complications occurred in three patients (0.8%). Malfunctions occurred in 197 patients (50%). Median tube patency was 103 days (95% CI, 71–134 days). No association was found between successful J-arm placement and gastric PEG tube position (P = 0.677), indication for jejunal nutrition (P = 0.349), J-arm trajectory in the stomach and incidence of malfunction (P = 0.365), risk of tube migration and PEG tube position (P = 0.173), or J-arm length (P = 0.987). A fluoroscopy time of 21.3 min was identified as a threshold for failure. Malfunctions occurred more often in tubes replaced after 90 days than in tubes replaced before 90 days (P < 0.001). A total of 42 aspiration events occurred (OR 6.4, P < 0.001, compared with nonmalfunctioning tubes). CONCLUSION Fluoroscopy-guided J-arm placement is safe for patients requiring jejunal nutrition. Tubes indwelling for longer than 90 days have higher rates of malfunction and aspiration. PMID:26380895

  8. 21 CFR 870.4390 - Cardiopulmonary bypass pump tubing.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Devices § 870.4390 Cardiopulmonary bypass pump tubing. (a) Identification. A cardiopulmonary bypass pump tubing is polymeric tubing which is used in the blood pump head and which is cyclically compressed by the pump to cause the blood to flow...

  9. 21 CFR 864.6150 - Capillary blood collection tube.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Capillary blood collection tube. 864.6150 Section...Hematology Devices § 864.6150 Capillary blood collection tube. (a) Identification. A capillary blood collection tube is a plain or...

  10. 21 CFR 868.5795 - Tracheal tube cleaning brush.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false Tracheal tube cleaning brush. 868.5795 Section 868.5795...Devices § 868.5795 Tracheal tube cleaning brush. (a) Identification. A tracheal tube cleaning brush is a device consisting of a...

  11. 21 CFR 868.5795 - Tracheal tube cleaning brush.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Tracheal tube cleaning brush. 868.5795 Section 868.5795...Devices § 868.5795 Tracheal tube cleaning brush. (a) Identification. A tracheal tube cleaning brush is a device consisting of a...

  12. 21 CFR 868.5795 - Tracheal tube cleaning brush.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Tracheal tube cleaning brush. 868.5795 Section 868.5795...Devices § 868.5795 Tracheal tube cleaning brush. (a) Identification. A tracheal tube cleaning brush is a device consisting of a...

  13. 21 CFR 868.5795 - Tracheal tube cleaning brush.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Tracheal tube cleaning brush. 868.5795 Section 868.5795...Devices § 868.5795 Tracheal tube cleaning brush. (a) Identification. A tracheal tube cleaning brush is a device consisting of a...

  14. 21 CFR 868.5795 - Tracheal tube cleaning brush.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false Tracheal tube cleaning brush. 868.5795 Section 868.5795...Devices § 868.5795 Tracheal tube cleaning brush. (a) Identification. A tracheal tube cleaning brush is a device consisting of a...

  15. Tube bending with axial pull and internal pressure 

    E-print Network

    Agarwal, Rohit

    2004-09-30

    Tube bending is a widely used manufacturing process in the aerospace, automotive, and other industries. During tube bending, considerable in-plane distortion and thickness variation occurs. The thickness increases at the intrados (surface of tube...

  16. Improved Autoassociative Neural Networks

    NASA Technical Reports Server (NTRS)

    Hand, Charles

    2003-01-01

    Improved autoassociative neural networks, denoted nexi, have been proposed for use in controlling autonomous robots, including mobile exploratory robots of the biomorphic type. In comparison with conventional autoassociative neural networks, nexi would be more complex but more capable in that they could be trained to do more complex tasks. A nexus would use bit weights and simple arithmetic in a manner that would enable training and operation without a central processing unit, programs, weight registers, or large amounts of memory. Only a relatively small amount of memory (to hold the bit weights) and a simple logic application- specific integrated circuit would be needed. A description of autoassociative neural networks is prerequisite to a meaningful description of a nexus. An autoassociative network is a set of neurons that are completely connected in the sense that each neuron receives input from, and sends output to, all the other neurons. (In some instantiations, a neuron could also send output back to its own input terminal.) The state of a neuron is completely determined by the inner product of its inputs with weights associated with its input channel. Setting the weights sets the behavior of the network. The neurons of an autoassociative network are usually regarded as comprising a row or vector. Time is a quantized phenomenon for most autoassociative networks in the sense that time proceeds in discrete steps. At each time step, the row of neurons forms a pattern: some neurons are firing, some are not. Hence, the current state of an autoassociative network can be described with a single binary vector. As time goes by, the network changes the vector. Autoassociative networks move vectors over hyperspace landscapes of possibilities.

  17. OXIDE DISPERSION-STRENGTHENED HEAT EXCHANGER TUBING

    SciTech Connect

    Harper, Mark A.

    2001-11-06

    Oxide dispersion strengthened (ODS) alloys (e.g. the INCOLOY{reg_sign} MA956 alloy) are known for their excellent high temperature properties and are prime candidate materials for the construction of very high temperature heat exchangers that will be used in Vision 21 power plants. The main limitation of these materials is their poor weldability. Commercially available ODS tubing also tends to exhibit relatively poor circumferential creep strength due to current processing practices resulting in a fine grain size in the transverse direction. Thus far, these two characteristics of the ODS tubing have restricted its use to mostly non-pressure containing applications. The objectives of this program are to develop: (a) an MA956 tube with sufficient circumferential creep strength for long term use as heat exchanger tubing for very high temperatures; (b) a welding technique(s) for producing adequate joints between an MA956 tube and an MA956 tube, and an MA956 tube and an INCONEL 601 tube; (c) the bending strain limits, below which recrystallization will not occur in a MA956 tube during normal operation; and (d) the high temperature corrosion limits for the MA956 alloy with respect to working-fluid side and fireside environments. Also, this program seeks to generate data for use by heat exchanger designers and the ASME Boiler and Pressure Vessel Code, and perform an analysis of the mechanical property, tube bending, and corrosion data in order to determine the implications on the design of a very high temperature heat exchanger (T>1093 C/2000 F). After one year, work is currently being conducted on increasing the circumferential strength of a MA956 tube, developing joining techniques for this material, determining the tube bending strain limits, and establishing the high temperature corrosion parameters for the MA956 alloy in environments expected to be present in Vision 21 power plants. Work in these areas will is continuing into the next fiscal year, with success anticipated to produce innovative developments that will allow the reliable use of ODS alloys for heat exchanger tubing, as well as a variety of applications previously not possible with metallic materials.

  18. Optics in neural computation

    NASA Astrophysics Data System (ADS)

    Levene, Michael John

    In all attempts to emulate the considerable powers of the brain, one is struck by both its immense size, parallelism, and complexity. While the fields of neural networks, artificial intelligence, and neuromorphic engineering have all attempted oversimplifications on the considerable complexity, all three can benefit from the inherent scalability and parallelism of optics. This thesis looks at specific aspects of three modes in which optics, and particularly volume holography, can play a part in neural computation. First, holography serves as the basis of highly-parallel correlators, which are the foundation of optical neural networks. The huge input capability of optical neural networks make them most useful for image processing and image recognition and tracking. These tasks benefit from the shift invariance of optical correlators. In this thesis, I analyze the capacity of correlators, and then present several techniques for controlling the amount of shift invariance. Of particular interest is the Fresnel correlator, in which the hologram is displaced from the Fourier plane. In this case, the amount of shift invariance is limited not just by the thickness of the hologram, but by the distance of the hologram from the Fourier plane. Second, volume holography can provide the huge storage capacity and high speed, parallel read-out necessary to support large artificial intelligence systems. However, previous methods for storing data in volume holograms have relied on awkward beam-steering or on as-yet non- existent cheap, wide-bandwidth, tunable laser sources. This thesis presents a new technique, shift multiplexing, which is capable of very high densities, but which has the advantage of a very simple implementation. In shift multiplexing, the reference wave consists of a focused spot a few millimeters in front of the hologram. Multiplexing is achieved by simply translating the hologram a few tens of microns or less. This thesis describes the theory for how shift multiplexing works based on an unconventional, but very intuitive, analysis of the optical far-field. A more detailed analysis based on a path-integral interpretation of the Born approximation is also derived. The capacity of shift multiplexing is compared with that of angle and wavelength multiplexing. The last part of this thesis deals with the role of optics in neuromorphic engineering. Up until now, most neuromorphic engineering has involved one or a few VLSI circuits emulating early sensory systems. However, optical interconnects will be required in order to push towards more ambitious goals, such as the simulation of early visual cortex. I describe a preliminary approach to designing such a system, and show how shift multiplexing can be used to simultaneously store and implement the immense interconnections required by such a project.

  19. Neural interfaces at the nanoscale

    PubMed Central

    Pancrazio, Joseph J

    2008-01-01

    Bioelectrical neural interfaces provide a means of recording the activity from the nervous system and delivering therapeutic stimulation to restore neurological function lost during disease or injury. Although neural interfaces have reached clinical utility, reducing the size of the bioelectrical interface to minimize damage to neural tissue and maximize selectivity has proven problematic. Nanotechnology may offer a means of interfacing with the nervous system with unprecedented specificity. Emergent applications of nanotechnology to neuroscience include molecular imaging, drug delivery across the BBB, scaffolds for neural regeneration and bioelectrical interfaces. In particular, carbon nanotubes offer the promises of material stability and low electrical impedance at physical dimensions that could have a significant impact on the future on neural interfaces. The purpose of this review is to present recent advances in carbon nanotube-based bioelectrical interfaces for the nervous system and discuss research challenges and opportunities. PMID:19025456

  20. Lowering the radioactivity of the photomultiplier tubes for the XENON1T dark matter experiment

    E-print Network

    Aprile, E; Alfonsi, M; Arazi, L; Arisaka, K; Arneodo, F; Auger, M; Balan, C; Barrow, P; Baudis, L; Bauermeister, B; Behrens, A; Beltrame, P; Brown, A; Brown, E; Bruenner, S; Bruno, G; Budnik, R; Buetikofer, L; Cardoso, J M R; Coderre, D; Colijn, A P; Contreras, H; Cussonneau, J P; Decowksi, M P; Di Giovanni, A; Duchovni, E; Fattori, S; Ferella, A D; Fieguth, A; Fulgione, W; Garbini, M; Geis, C; Goetzke, L W; Grignon, C; Gross, E; Hampel, W; Itay, R; Kaether, F; Kessler, G; Kish, A; Landsman, H; Lang, R F; Calloch, M Le; Lellouch, D; Levinson, L; Levy, C; Lindemann, S; Lindner, M; Lopes, J A M; Lyashenko, A; Macmullin, S; Undagoitia, T Marrodan; Masbou, J; Massoli, F V; Mayani, D; Fernandez, A J Melgarejo; Meng, Y; Messina, M; Miguez, B; Molinario, A; Morana, G; Murra, M; Naganoma, J; Oberlack, U; Orrigo, S E A; Pakarha, P; Pantic, E; Persiani, R; Piastra, F; Pienaar, J; Plante, G; Priel, N; Rauch, L; Reichard, S; Reuter, C; Rizzo, A; Rosendahl, S; Santos, J M F dos; Sartorelli, G; Schindler, S; Schreiner, J; Schumann, M; Lavina, L Scotto; Selvi, M; Shagin, P; Simgen, H; Teymourian, A; Thers, D; Tiseni, A; Trinchero, G; Tunnell, C; Vitells, O; Wall, R; Wang, H; Weber, M; Weinheimer, C; Laubenstein, M

    2015-01-01

    The low-background, VUV-sensitive 3-inch diameter photomultiplier tube R11410 has been developed by Hamamatsu for dark matter direct detection experiments using liquid xenon as the target material. We present the results from the joint effort between the XENON collaboration and the Hamamatsu company to produce a highly radio-pure photosensor (version R11410-21) for the XENON1T dark matter experiment. After introducing the photosensor and its components, we show the methods and results of the radioactive contamination measurements of the individual materials employed in the photomultiplier production. We then discuss the adopted strategies to reduce the radioactivity of the various PMT versions. Finally, we detail the results from screening 216 tubes with ultra-low background germanium detectors, as well as their implications for the expected electronic and nuclear recoil background of the XENON1T experiment.