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Sample records for pulsating embryonic chick

  1. Transplantation of human neonatal foreskin stromal cells in ex vivo organotypic cultures of embryonic chick femurs

    DEFF Research Database (Denmark)

    Aldahmash, Abdullah; Vishnubalaji, Radhakrishnan

    2017-01-01

    NSSCs in ex vivo organotypic cultures of embryonic chick femurs. Isolated embryonic chick femurs (E10 and E11) were cultured for 10 days together with micro-mass cell pellets of hNSSCs, human umbilical vein endothelial cells (HUVEC) or a combination of the two cell types. Changes in femurs gross morphology...

  2. Retroviral expression of connexins in embryonic chick lens.

    Science.gov (United States)

    Jiang, J X; Goodenough, D A

    1998-03-01

    To develop an in vivo model system in which exogenous proteins can be expressed in embryonic chick lens and to further understand the function of connexin-mediated gap junction intercellular communication in lens cell biology. RCAS(A) is a replication-competent chicken retrovirus that infects dividing cells. Retroviral constructs were prepared containing alkaline phosphatase (AP) and FLAG-tagged connexins. Chick lenses were infected in situ by injecting virus into the lumen of lens vesicles at stage 18, cultures were taken at various periods. The lenses were then dissected, and the expressed proteins were visualized by AP histochemical examination and immunostaining. Twenty-four hours after infection, alkaline phosphatase could be seen in epithelia and fibers. As lens fiber maturation progressed, however, the alkaline phosphatase staining was lost as the fibers matured, presumably because of the proteolytic removal of the enzyme. By 72 hours, alkaline phosphatase staining could still be observed in epithelial cells and in differentiating fibers in the bow region but not in the mature lens fibers. FLAG-tagged exogenous lens connexins were also abundantly expressed by viral infection. The exogenous connexins were localized at the cell surfaces in junctional maculae and showed the same cell-type specific distribution as that of their endogenous connexin counterparts. An in vivo model system has been developed in the chick that provides opportunities to study the expression of wild-type and mutant proteins during lens differentiation. Expression of wild-type connexins has revealed that the characteristic distribution of the three different lens connexins is maintained even when expression is driven by a viral promoter.

  3. Fine structure of Plasmodium gallinaceum in embryonic and neonate chicks.

    Science.gov (United States)

    Lushbaugh, W B; McGhee, R B; Singh, S D

    1976-02-01

    The erythrocytic stages of Plasmdoium gallinaceum in chicken embryos injected with parasited blood either from a syringe-passaged infection in chickens or from a chicken infected with sporozoites were characterized by abnormal structure. Particularly evident were large, unstained vacuoles within the cytoplasm; these occurred with greatest frequency in schizonts. The presence of myelin bodies within these vacuoles was revealed by transmission electron microscopy; abnormal cytokinesis and aberrant merozoites provided additional evidence of the parasite's inability to develop naturally within the milieu of the embryonic erythrocytes. Fifty-five passages were necessary to restore normal structure of the parasites in embryos, while only 5 passages were required for such restoration in neonate chicks. The probable adaptation of the parasite to the proportions of hemoglobin of the adult chicken may be responsible for the abnormal growth in the immature host.

  4. Studies on the Relationship between the Embryonic Heart Development and the Amnion Folding in Chick

    Directory of Open Access Journals (Sweden)

    Yongqing Li

    2006-01-01

    Full Text Available As a model animal for developmental biology, chick embryo is easy to control and observe during embryo development period and therefore it is widely used in the study of cardiac development. The application of proteomics has opened the door for large-scale studies to dissect both protein expression, regulation and function during chick heart developing stages. The proteomics study requires to quickly separate a large number of chick heart samples with the same developing stage. However, the traditional morphological standards based on Hamburger-Hamilton and Witschi stages are difficult to fulfill this requirement. Herein, we suppose a new standard for distinguishing chick heart morphology in different developing stages based on the relationship between the embryonic heart development and the amnion folding in chick. Based on this standard, we can accelerate the speed of embryonic heart sample separation and guarantee the quantity and quality of the sample more reliably.

  5. AN EMBRYONIC CHICK PANCREAS ORGAN CULTURE MODEL: CHARACTERIZATION AND NEURAL CONTROL OF EXOCRINE RELEASE

    Science.gov (United States)

    An embryonic chick (Gallus domesticus) whole-organ pancreas culture system was developed for use as an in vitro model to study cholinergic regulation of exocrine pancreatic function. The culture system was examined for characteristic exocrine function and viability by measuring e...

  6. AN EMBRYONIC CHICK PANCREAS ORGAN CULTURE MODEL: CHARACTERIZATION AND NEURAL CONTROL OF EXOCRINE RELEASE

    Science.gov (United States)

    An embryonic chick (Gallus domesticus) whole-organ pancreas culture system was developed for use as an in vitro model to study cholinergic regulation of exocrine pancreatic function. The culture system was examined for characteristic exocrine function and viability by measuring e...

  7. Generation of the Dimensional Embryology Application (App) for Visualization of Early Chick and Frog Embryonic Development

    Science.gov (United States)

    Webb, Rebecca L.; Bilitski, James; Zerbee, Alyssa; Symans, Alexandra; Chop, Alexandra; Seitz, Brianne; Tran, Cindy

    2015-01-01

    The study of embryonic development of multiple organisms, including model organisms such as frogs and chicks, is included in many undergraduate biology programs, as well as in a variety of graduate programs. As our knowledge of biological systems increases and the amount of material to be taught expands, the time spent instructing students about…

  8. Pyridoxine treatment alters embryonic motility in chicks: Implications for the role of proprioception.

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    Sharp, Andrew A; Bekoff, Anne

    2015-03-01

    Somatosensory feedback is important for the modulation of normal locomotion in adult animals, but we do not have a good understanding of when somatosensory information is first used to modulate motility during embryogenesis or how somatosensation is first used to regulate motor output. We used pyridoxine administration (vitamin B6 ), which is known to mostly kill proprioceptive neurons in adult mammals and embryonic chicks, to explore the role of proprioceptive feedback during early embryonic motility in the chick. Injection of pyridoxine on embryonic day 7 (E7) and E8 reduced the amplitude of leg movements recorded on E9 and the number of large, healthy neurons in the ventral-lateral portion of the DRGs. We conclude that proprioception is initially used during embryogenesis to modulate the strength of motor output, but that it is not incorporated into other aspects of pattern generation until later in development as poly-synaptic pathways develop.

  9. Measurement of strain and strain rate in embryonic chick heart using spectral domain optical coherence tomography

    Science.gov (United States)

    Dou, Shidan; Suo, Yanyan; Liang, Chengbo; Wang, Yi; Zhao, Yuqian; Liu, Jian; Xu, Tao; Wang, Ruikang; Ma, Zhenhe

    2016-03-01

    It is important to measure embryonic heart myocardial wall strain and strain rate for understanding the mechanisms of embryonic heart development. Optical coherence tomography (OCT) can provide depth resolved images with high spatial and temporal resolution, which makes it have the potential to reveal the complex myocardial activity in the early stage embryonic heart. We develop a novel method to measure strain in embryonic chick heart based on spectral domain OCT images and subsequent image processing. We perform 4D(x,y,z,t) scanning on the outflow tract (OFT) of chick embryonic hearts in HH18 stage (~3 days of incubation). Only one image sequence acquired at the special position is selected based on the Doppler blood flow information where the probe beam penetrates through the OFT perpendicularly. For each image of the selected sequence, the cross-section of the myocardial wall can be approximated as an annulus. The OFT is segmented with a semi-automatic boundary detection algorithm, thus the area and mean circumference of the annular myocardial wall can be achieved. The myocardial wall thickness was calculated using the area divided by the mean circumference, and then the strain was obtained. The results demonstrate that OCT can be a useful tool to describe the biomechanical characteristics of the embryonic heart.

  10. Synthesis of type III collagen by fibroblasts from the embryonic chick cornea

    OpenAIRE

    1980-01-01

    Synthesis of collagen types I, II, III, and IV in cells from the embryonic chick cornea was studied using specific antibodies and immunofluorescence. Synthesis of radioactively labeled collagen types I and III was followed by fluorographic detection of cyanogen bromide peptides on polyacrylamide slab gels and by carboxymethylcellulose chromatography followed by disc gel electrophoresis. Type III collagen had been detected previously by indirect immunofluorescence in the corneal epithelial cel...

  11. Mathematical Modeling of Flow Characteristics in the Embryonic Chick Heart

    DEFF Research Database (Denmark)

    Heebøll-Christensen, Jesper

    . Furthermore it is concluded that the observed Liebau effect does depend on the impedance of the tubes, the frequency and position of the compression pump, but above all the characterization of the pumping function. Different pumping functions are employed in the modeling but no defining characteristics...... modified inertia, and resistance due to friction and curvature of the multilayered tubular heart. Through the modeling, flow conditions in the embryonic heart are characterized. The models suggest that eccentric rather than concentric deformation of the beating heart is optimal for mean flows induced...... the models are not conclusive on this point. In addition the Liebau effect is investigated in a simpler system containing two elastic tubes joined to form a liquid filled ring, with a compression pump at an asymmetric location. Through comparison to other reports the system validates model construction...

  12. Measurement of wall shear stress in chick embryonic heart using optical coherence tomography

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    Ma, Zhenhe; Dou, Shidan; Zhao, Yuqian; Wang, Yi; Suo, Yanyan; Wang, Fengwen

    2015-03-01

    The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) is one of the components which have been proved to influence the morphogenesis during early stages of cardiac development. To study the mechanism, WSS measurement is a step with significant importance. WSS is caused by blood flow imposed on the inner surface of the heart wall and it can be determined by calculating velocity gradients of blood flow in a direction perpendicular to the wall. However, the WSS of the early stage embryonic heart is difficult to measure since the embryonic heart is tiny and beating fast. Optical coherence tomography (OCT) is a non-invasive imaging modality with high spatial and temporal resolution, which is uniquely suitable for the study of early stage embryonic heart development. In this paper, we introduce a method to measure the WSS of early stage chick embryonic heart based on high speed spectral domain optical coherence tomography (SDOCT). 4D (x,y,z,t) scan was performed on the outflow tract (OFT) of HH18 (~3 days of incubation) chick embryonic heart. After phase synchronization, OFT boundary segmentation, and OFT center line calculation, Doppler angle of the blood flow in the OFT can be achieved (This method has been described in previous publications). Combining with the Doppler OCT results, we calculate absolute blood flow velocity distribution in the OFT. The boundary of the OFT was segmented at each cross-sectional structural image, then geometrical center of the OFT can be calculated. Thus, the gradients of blood flow in radial direction can be calculated. This velocity gradient near the wall is termed wall shear rate and the WSS value is proportional to the wall shear rate. Based on this method, the WSS at different heart beating phase are compare. The result demonstrates that OCT is capable of early stage chicken embryonic heart WSS study.

  13. Spaceflight effects on cultured embryonic chick bone cells

    Science.gov (United States)

    Landis, W. J.; Hodgens, K. J.; Block, D.; Toma, C. D.; Gerstenfeld, L. C.

    2000-01-01

    A model calcifying system of primary osteoblast cell cultures derived from normal embryonic chicken calvaria has been flown aboard the shuttle, Endeavour, during the National Aeronautics and Space Administration (NASA) mission STS-59 (April 9-20, 1994) to characterize unloading and other spaceflight effects on the bone cells. Aliquots of cells (approximately 7 x 10(6)) grown in Dulbecco's modified Eagle's medium (DMEM) + 10% fetal bovine serum (FBS) were mixed with microcarrier beads, inoculated into cartridge culture units of artificial hollow fiber capillaries, and carried on the shuttle. To promote cell differentiation, cartridge media were supplemented with 12.5 microg/ml ascorbate and 10 mM beta-glycerophosphate for varying time periods before and during flight. Four cartridges contained cells from 17-day-old embryos grown for 5 days in the presence of ascorbate prior to launch (defined as flight cells committed to the osteoblastic lineage) and four cartridges supported cells from 14-day-old embryos grown for 10 days with ascorbate before launch (uncommitted flight cells). Eight cartridges prepared in the same manner were maintained under normal gravity throughout the flight (control cells) and four additional identical cartridges under normal gravity were terminated on the day of launch (basal cells). From shuttle launch to landing, all cartridges were contained in closed hardware units maintaining 5% CO2, 37 degrees C, and media delivery at a rate of approximately 1.5 ml/6 h. During day 3 and day 5 of flight, duplicate aliquots of conditioned media and accumulated cell products were collected in both the flight and the control hardware units. At the mission end, comparisons among flight, basal, and control samples were made in cell metabolism, gene expression for type I collagen and osteocalcin, and ultrastructure. Both committed and uncommitted flight cells were metabolically active, as measured by glucose uptake and lactate production, at approximately the

  14. Cadmium inhibition of vitamin D-mediated responses in organ-cultured embryonic chick duodenum

    Energy Technology Data Exchange (ETDEWEB)

    Corradino, R.A.

    1979-01-01

    When added to the medium, cadmium inhibits 1..cap alpha..,25-dihydroxycholecalciferol-mediated responses in the organ-cultured embryonic chick duodenum: decreases induction of a specific calcium-binding protein (CaBP), prevents the elevation of alkaline phosphatase activity, and reduces the ability of the tissue to absorb radiocalcium at the mucosal surface. The cadmium effect is clearly not generalized cytotoxicity. These results may be taken as evidence that cadmium can interfere with vitamin D action at the level of the target organ itself and is not necessarily secondary to alteration in vitamin D metabolism.

  15. Distribution of microglial cells in the cerebral hemispheres of embryonic and neonatal chicks

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    A.R. Ignácio

    2005-11-01

    Full Text Available The distribution, morphology and morphometry of microglial cells in the chick cerebral hemispheres from embryonic day 4 (E4 to the first neonatal day (P1 were studied by histochemical labeling with a tomato (Lycopersicon esculentum lectin. The histochemical analysis revealed lectin-reactive cells in the nervous parenchyma on day E4. Between E4 (5.7 ± 1.35 mm length and E17 (8.25 ± 1.2 mm length, the lectin-reactive cells were identified as ameboid microglia and observed starting from the subventricular layer, distributed throughout the mantle layer and in the proximity of the blood vessels. After day E13, the lectin-reactive cells exhibited elongated forms with small branched processes, and were considered primitive ramified microglia. Later, between E18 (5.85 ± 1.5 mm cell body length and P1 (3.25 ± 0.6 mm cell body length, cells with more elongated branched processes were observed, constituting the ramified microglia. Our findings provide additional information on the migration and differentiation of microglial cells, whose ramified form is observed at the end of embryonic development. The present paper focused on the arrangement of microglial cells in developing cerebral hemispheres of embryonic and neonatal chicks, which are little studied in the literature. Details of morphology, morphometry and spatial distribution of microglial cells contributed to the understanding of bird and mammal central nervous system ontogeny. Furthermore, the identification and localization of microglial cells during the normal development could be used as a morphological guide for embryonic brain injury researches.

  16. Quantitative analysis of nerve growth factor in the amniotic fluid during chick embryonic development.

    Science.gov (United States)

    Mashayekhi, Farhad; Dianati, Elham; Moghadam, Lotfali Masomi

    2011-04-01

    Nerve growth factor (NGF) and most neurotrophic factors support the proliferation and survival of particular types of neurons. Besidesthe pivotal role of NGF in the development of neuronal cells, it also has important functions on non-neuronal cells. The amnion surrounds the embryo, providing an aqueous environment for the embryo. A wide range of proteins has been identified in human amniotic fluid (AF). In this study, total protein concentration (TPC) and NGF level in AF samples from chick embryos were measured using a Bio-Rad protein assay, enzyme linked immunosorbent assay (ELISA) and Western blot. TPC increased from days E10 to day E18. There was a rapid increase in AF TPC on day E15 when compared to day E16. No significant changes in NGF levels have been seen from day E10 to day E14. There was a rapid increase in NGF content on days E15 and E16, and thereafter the levels decreased from day E16 to day E18. Since, NGF is important in brain development and changes in AF NGF levels have been seen in some CNS malformations, changes in the TPC and NGF levels in AF during chick embryonic development may be correlated with cerebral cortical development. It is also concluded that NGF is a constant component of the AF during chick embryogenesis.

  17. Regulation of phosphatidylcholine biosynthesis in cultured chick embryonic muscle treated with phospholipase C.

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    Sleight, R; Kent, C

    1980-11-25

    Cultures of embryonic chick muscle cells grown in medium containing phospholipase C from Clostridium perfringens incorporated [3H]choline into lipid at a rate 3- to 5-fold higher than control cultures. To determine the mechanism by which stimulation of phosphatidylcholine synthesis occurred in phospholipase C-treated cells, activities of enzymes and levels of intermediates in the biosynthetic pathway for phosphatidylcholine were examined. Activities of choline kinase, choline phosphotransferase, glycerol-3-phosphate dehydrogenase, glycerol-3-phosphate acyltransferase, acylglycerol-3-phosphate acyltransferase, and phosphatidic acid phosphatase in phospholipase C-treated cells were the same or only slightly higher than in control cells. CTP:phosphocholine cytidylyltransferase, on the other hand, was 3 times as active in homogenates from phospholipase C-treated cells. Levels of phosphocholine decreased and levels of CDP-choline increased in phospholipase C-treated cells, and a calculation of the disequilibrium ratio indicated that the cytidylyltransferase reaction was not at equilibrium. The cytidylyltransferase was, thus, identified as the regulatory enzyme for choline flux in these cells. The cytidylyltransferase was located in both the cytosolic and particulate fractions from cultured muscle cells and a much larger portion of enzyme activity was associated with the particulate fraction in cells treated with phospholipase C. Sonicated preparations of total chick lipids, phosphatidylethanolamine, and phosphatidylserine greatly stimulated the cytosolic cytidylyltransferase activity but had no effect on the particulate enzyme. Neither stimulation of incorporation of [3H]choline into lipid nor activation of the cytidylyltransferase was dependent on protein synthesis. A model for the mechanism of regulation of phosphatidylcholine synthesis in embryonic chick muscle is presented.

  18. Gene transfer to chicks using lentiviral vectors administered via the embryonic chorioallantoic membrane.

    Directory of Open Access Journals (Sweden)

    Gideon Hen

    Full Text Available The lack of affordable techniques for gene transfer in birds has inhibited the advancement of molecular studies in avian species. Here we demonstrate a new approach for introducing genes into chicken somatic tissues by administration of a lentiviral vector, derived from the feline immunodeficiency virus (FIV, into the chorioallantoic membrane (CAM of chick embryos on embryonic day 11. The FIV-derived vectors carried yellow fluorescent protein (YFP or recombinant alpha-melanocyte-stimulating hormone (α-MSH genes, driven by the cytomegalovirus (CMV promoter. Transgene expression, detected in chicks 2 days after hatch by quantitative real-time PCR, was mostly observed in the liver and spleen. Lower expression levels were also detected in the brain, kidney, heart and breast muscle. Immunofluorescence and flow cytometry analyses confirmed transgene expression in chick tissues at the protein level, demonstrating a transduction efficiency of ∼0.46% of liver cells. Integration of the viral vector into the chicken genome was demonstrated using genomic repetitive (CR1-PCR amplification. Viability and stability of the transduced cells was confirmed using terminal deoxynucleotidyl transferase (dUTP nick end labeling (TUNEL assay, immunostaining with anti-proliferating cell nuclear antigen (anti-PCNA, and detection of transgene expression 51 days post transduction. Our approach led to only 9% drop in hatching efficiency compared to non-injected embryos, and all of the hatched chicks expressed the transgenes. We suggest that the transduction efficiency of FIV vectors combined with the accessibility of the CAM vasculature as a delivery route comprise a new powerful and practical approach for gene delivery into somatic tissues of chickens. Most relevant is the efficient transduction of the liver, which specializes in the production and secretion of proteins, thereby providing an optimal target for prolonged study of secreted hormones and peptides.

  19. Integration of human model neurons (NT2) into embryonic chick nervous system.

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    Podrygajlo, Grzegorz; Wiegreffe, Christoph; Scaal, Martin; Bicker, Gerd

    2010-02-01

    Postmitotic neurons were generated from the human NT2 teratocarcinoma cell line in a novel cell aggregate differentiation procedure. Approximately a third of the differentiated neurons expressed cell markers related to cholinergic neurotransmission. To examine whether this human cell model system can be directed toward a motoneuronal fate, postmitotic neurons were co-cultured with mouse myotubes. Outgrowing neuronal processes established close contact with the myotubes and formed neuromuscular junction-like structures that bound alpha-bungarotoxin. To determine how grafted precursor cells and neurons respond to embryonic nerve tissue, NT2 cells at different stages of neural development were injected into chick embryo neural tube and brain. Grafted NT2 neurons populated both parts of the nervous system, sometimes migrating away from the site of injection. The neural tube appeared to be more permissive for neurite extensions than the brain. Moreover, extending neurites of spinal grafts were approaching the ventral roots, thus resembling motoneuronal projections.

  20. The impact of caffeine on connexin expression in the embryonic chick cardiomyocyte micromass culture system.

    Science.gov (United States)

    Ahir, Bhavesh K; Pratten, Margaret K

    2016-07-01

    Cardiomyocytes are electrically coupled by gap junctions, defined as clusters of low-resistance multisubunit transmembrane channels composed of connexins (Cxs). The expression of Cx40, Cx43 and Cx45, which are present in cardiomyocytes, is known to be developmentally regulated. This study investigates the premise that alterations in gap junction proteins are one of the mechanisms by which teratogens may act. Specifically, those molecules known to be teratogenic in humans could cause their effects via disruption of cell-to-cell communication pathways, resulting in an inability to co-ordinate tissue development. Caffeine significantly inhibited contractile activity at concentrations above and including 1500 μm (P caffeine on key cardiac gap junction protein (Cx40, Cx43 and Cx45) expression were analysed using immunocytochemistry and in-cell Western blotting. The results indicated that caffeine altered the expression pattern of Cx40, Cx43 and Cx45 at non-cytotoxic concentrations (≥2000 μm), i.e., at concentrations that did not affect total cell protein and cell viability. In addition the effects of caffeine on cardiomyocyte formation and function (contractile activity score) were correlated with modulation of Cxs (Cx40, Cx43 and Cx45) expression, at above and including 2000 μm caffeine concentrations (P < 0.05). These experiments provide evidence that embryonic chick cardiomyocyte micromass culture may be a useful in vitro method for mechanistic studies of perturbation of embryonic heart development. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Characterization of miRNA processing machinery in the embryonic chick lung.

    Science.gov (United States)

    Moura, Rute Silva; Vaz-Cunha, Patrícia; Silva-Gonçalves, Carla; Correia-Pinto, Jorge

    2015-12-01

    Lung development is a very complex process that relies on the interaction of several signaling pathways that are controlled by precise regulatory mechanisms. Recently, microRNAs (miRNAs), small non-coding regulatory RNAs, have emerged as new players involved in gene expression regulation controlling several biological processes, such as cellular differentiation, apoptosis and organogenesis, in both developmental and disease processes. Failure to correctly express some specific miRNAs or a component of their biosynthetic machinery during embryonic development is disastrous, resulting in severe abnormalities. Several miRNAs have already been identified as modulators of lung development. Regarding the spatial distribution of the processing machinery of miRNAs, only two of its members (dicer1 and argonaute) have been characterized. The present work characterizes the expression pattern of drosha, dgcr8, exportin-5 and dicer1 in early stages of the embryonic chick lung by whole mount in situ hybridization and cross-section analysis. Overall, these genes are co-expressed in dorsal and distal mesenchyme and also in growing epithelial regions. The expression pattern of miRNA processing machinery supports the previously recognized regulatory role of this mechanism in epithelial and mesenchymal morphogenesis.

  2. Cell interactions between hematopoietic and stromal cells in the embryonic chick bone marrow.

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    Sorrell, J M; Weiss, L

    1980-05-01

    Light microscopic, scanning electron microscopic, and transmission electron microscopic studies of the early developmental stages of chick embryonic bone marrow disclose characteristic associations of the first hematopoietic cells with stromal cells. The first hematopoietic cells, large basophilic cells that we have termed presumptive stem cells, segregate into erythropoietic and granulopoietic regions. Intravascular erythropoietic cells associate with sinusoidal endothelial cells, while granulopoietic cells associate with extravascular reticular cells. Extensive, intimate contacts between erythroid and endothelial cells are maintained, in part, by marginal arrays of microtubules, which promote a flattening of the adherent erythroid cell surface. In addition, cell surface components of opposing cells, visualized by ruthenium red staining, appear to merge and possibly to interact. Granulopoietic cells establish intimate but less extensive associations with reticular cells through cell-surface interactions. Stationary granuloid cells appear to be held in place by small, thin processes emanating from the sheet-like reticular cells. Granuloid cells are capable of moving within the extravascular region, using reticular cell surfaces as a substrate. Intimate associations also occur among granulopoietic cells, the significance of which is unclear. Thus, sinusoidal endothelial cells and reticular cells comprise the critical non-hematopoietic or stromal elements of avian bone marrow, where they have a putative role in segregating presumptive stem cells into erythrocyteic and granulocytic compartments. They serve as an architectual, and possibly regulatory, framework on which hematopoiesis occurs.

  3. Evaluation of embryotoxicity for major components of herbal extracts using the chick embryonic heart micromass and mouse D3 embryonic stem cell systems.

    Science.gov (United States)

    Mohammed, Omar J; Latif, Muhammad Liaque; Pratten, Margaret K

    2016-01-01

    Herbal remedies are often used during the early stages of pregnancy, being considered 'harmless' and 'natural'. There are insufficient data regarding their potential embryotoxicity. The main components of selected herbs, including 6-gingerol from ginger, Ginkgolide A and Ginkgolide B from gingko biloba and Ginsenoside Rg1 from ginseng, have been investigated using chick embryonic heart micromass and Mouse D3 embryonic stem cells. The potential effects were evaluated via alteration in contractility, cell viability, and cell protein content. The myocytes in both systems were also demonstrated by immunocytochemistry using a specific cardiomyocyte marker (α-actinin). For 6-gingerol, Ginkgolide A, Ginkgolide B and Ginsenoside Rg1 in both methods, at moderate to high concentrations, there were alterations in the values for the endpoints. These data indicate that herbal remedies used in the first trimester of pregnancy might not be safe for fetal development.

  4. Cytoskeletal heart-enriched actin-associated protein (CHAP) is expressed in striated and smooth muscle cells in chick and mouse during embryonic and adult stages.

    Science.gov (United States)

    van Eldik, Willemijn; Beqqali, Abdelaziz; Monshouwer-Kloots, Jantine; Mummery, Christine; Passier, Robert

    2011-01-01

    We recently identified a new Z-disc protein, CHAP (Cytoskeletal Heart-enriched Actin-associated Protein), which is expressed in striated muscle and plays an important role during embryonic muscle development in mouse and zebrafish. Here, we confirm and further extend these findings by (i) the identification and characterization of the CHAP orthologue in chick and (ii) providing a detailed analysis of CHAP expression in mouse during embryonic and adult stages. Chick CHAP contains a PDZ domain and a nuclear localization signal, resembling the human and mouse CHAPa. CHAP is expressed in the developing heart and somites, as well as muscle precursors of the limb buds in mouse and chick embryos. CHAP expression in heart and skeletal muscle is maintained in adult mice, both in slow and fast muscle fibers. Moreover, besides expression in striated muscle, we demonstrate that CHAP is expressed in smooth muscle cells of aorta, carotid and coronary arteries in adult mice, but not during embryonic development.

  5. Relationship of primary and secondary myogenesis to fiber type development in embryonic chick muscle.

    Science.gov (United States)

    Fredette, B J; Landmesser, L T

    1991-01-01

    The formation of fast and slow myotubes was investigated in embryonic chick muscle during primary and secondary myogenesis by immunocytochemistry for myosin heavy chain and Ca2(+)-ATPase. When antibodies to fast or slow isoforms of these two molecules were used to visualize myotubes in the posterior iliotibialis and iliofibularis muscles, one of the isoforms was observed in all primary and secondary myotubes until very late in development. In the case of myosin, the fast antibody stained virtually all myotubes until after stage 40, when fast myosin expression was lost in the slow myotubes of the iliofibularis. In the case of Ca2(+)-ATPase, the slow antibody also stained all myotubes until after stage 40, when staining was lost in secondary myotubes and in the fast primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis. In contrast, the antibodies against slow muscle myosin heavy chain and fast muscle Ca2(+)-ATPase stained mutually exclusive populations of myotubes at all developmental stages investigated. During primary myogenesis, fast Ca2(+)-ATPase staining was restricted to the primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis, whereas slow myosin heavy chain staining was confined to all of the primary myotubes of the slow region of the iliofibularis. During secondary myogenesis, the fast Ca2(+)-ATPase antibody stained nearly all secondary myotubes, while primaries in the slow region of the iliofibularis remained negative. Thus, in the slow region of the iliofibularis muscle, these two antibodies could be used in combination to distinguish primary and secondary myotubes. EM analysis of staining with the fast Ca2(+)-ATPase antibody confirmed that it recognizes only secondary myotubes in this region. This study establishes that antibodies to slow myosin heavy chain and fast Ca2(+)-ATPase are suitable markers for selective labeling of primary and secondary myotubes in the iliofibularis; these

  6. Blood flowing state analysis in outflow tract of chick embryonic heart based on spectral domain optical coherence tomography

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    Zhao, Yuqian; Suo, Yanyan; Liang, Chengbo; Ma, Zhenhe

    2016-03-01

    The cardiac development is a complicated process affected by genetic and environmental factors. Wall shear stress (WSS) and periodic stress (WPS) are the components which have been proved to influence the morphogenesis during early stages of cardiac development. The vessel wall will be deformed by the blood pressure and produce natural elastic force acting on the blood. Because blood flowing in different flow state and show different characteristics of fluid, which influence the calculation of WSS and WPS directly, it is necessary to study the blood flow state. In this paper, we introduce a method to quantify the blood flowing state of early stage chick embryonic heart based on high speed spectral domain optical coherence tomography (SDOCT).4D (x,y,z,t) scan was performed on the outflow tract (OFT) of HH18 (~3 days of incubation) chick embryonic heart. By processing the structural image, the geometric parameters were obtained. Blood flow velocity distribution in the OFT were calculated by Doppler OCT method. Hemodynamic parameters were obtained at different times during the cardiac cycle used biofluid mechanics theory, such as Reynolds number and Womersley number.

  7. Thioredoxin-2 Modulates Neuronal Programmed Cell Death in the Embryonic Chick Spinal Cord in Basal and Target-Deprived Conditions.

    Directory of Open Access Journals (Sweden)

    Marc Pirson

    Full Text Available Thioredoxin-2 (Trx2 is a mitochondrial protein using a dithiol active site to reduce protein disulfides. In addition to the cytoprotective function of this enzyme, several studies have highlighted the implication of Trx2 in cellular signaling events. In particular, growing evidence points to such roles of redox enzymes in developmental processes taking place in the central nervous system. Here, we investigate the potential implication of Trx2 in embryonic development of chick spinal cord. To this end, we first studied the distribution of the enzyme in this tissue and report strong expression of Trx2 in chick embryo post-mitotic neurons at E4.5 and in motor neurons at E6.5. Using in ovo electroporation, we go on to highlight a cytoprotective effect of Trx2 on the programmed cell death (PCD of neurons during spinal cord development and in a novel cultured spinal cord explant model. These findings suggest an implication of Trx2 in the modulation of developmental PCD of neurons during embryonic development of the spinal cord, possibly through redox regulation mechanisms.

  8. Effect of temperature on incubation period, embryonic mortality, hatch rate, egg water loss and partridge chick weight (Rhynchotus rufescens

    Directory of Open Access Journals (Sweden)

    Nakage ES

    2003-01-01

    Full Text Available The aim of this study was to determine the effects of incubation temperature (34.5; 35.5; 36.5; 37.5 and 38.5ºC, on incubation period, embryonic mortality, hatching rate, water loss and chick weight at hatch, using daily incubation of partridge (Rhynchotus rufescens eggs. The highest hatching percentage was obtained between 35.5 and 36.5ºC. Incubation length and temperature were inversely proportional. Water loss was lower in eggs incubated at low temperatures as compared to high temperatures. There was no difference among incubation temperatures in absolute and relative hatchling weights. Early embryonic mortality increased at low temperatures (36.5ºC. Our results show that, under conditions of daily incubation of eggs in the same incubator, higher hatching rate can be obtained using temperatures between 35.5ºC and 36.5ºC; incubation temperature is inversely proportional to incubation length, and absolute and relative weights of partridge chicks are not affected by incubation temperature.

  9. Circadian profiles in the embryonic chick heart: L-type voltage-gated calcium channels and signaling pathways.

    Science.gov (United States)

    Ko, Michael L; Shi, Liheng; Grushin, Kirill; Nigussie, Fikru; Ko, Gladys Y-P

    2010-10-01

    Circadian clocks exist in the heart tissue and modulate multiple physiological events, from cardiac metabolism to contractile function and expression of circadian oscillator and metabolic-related genes. Ample evidence has demonstrated that there are endogenous circadian oscillators in adult mammalian cardiomyocytes. However, mammalian embryos cannot be entrained independently to light-dark (LD) cycles in vivo without any maternal influence, but circadian genes are well expressed and able to oscillate in embryonic stages. The authors took advantage of using chick embryos that are independent of maternal influences to investigate whether embryonic hearts could be entrained under LD cycles in ovo. The authors found circadian regulation of L-type voltage-gated calcium channels (L-VGCCs), the ion channels responsible for the production of cardiac muscle contraction in embryonic chick hearts. The mRNA levels and protein expression of VGCCα1C and VGCCα1D are under circadian control, and the average L-VGCC current density is significantly larger when cardiomyocytes are recorded during the night than day. The phosphorylation states of several kinases involved in insulin signaling and cardiac metabolism, including extracellular signal-regulated kinase (Erk), stress-activated protein kinase (p38), protein kinase B (Akt), and glycogen synthase kinase-3β (GSK-3β), are also under circadian control. Both Erk and p38 have been implicated in regulating cardiac contractility and in the development of various pathological states, such as cardiac hypertrophy and heart failure. Even though both Erk and phosphoinositide 3-kinase (PI3K)-Akt signaling pathways participate in complex cellular processes regarding physiological or pathological states of cardiomyocytes, the circadian oscillators in the heart regulate these pathways independently, and both pathways contribute to the circadian regulation of L-VGCCs.

  10. Influence of air composition during egg storage on egg characteristics, embryonic development, hatchability, and chick quality

    NARCIS (Netherlands)

    Reijrink, I.A.M.; Duijvendijk, van L.A.G.; Meijerhof, R.; Kemp, B.; Brand, van den H.

    2010-01-01

    Egg storage beyond 7 d is associated with an increase in incubation duration and a decrease in hatchability and chick quality. Negative effects of prolonged egg storage may be caused by changes in the embryo, by changes in egg characteristics, or by both. An adjustment in storage air composition may

  11. Assessment of developmental cardiotoxic effects of some commonly used phytochemicals in mouse embryonic D3 stem cell differentiation and chick embryonic cardiomyocyte micromass culture models.

    Science.gov (United States)

    Mohammed, Omar J; McAlpine, Roseanna; Chiewhatpong, Phasawee; Latif, Muhammad Liaque; Pratten, Margaret K

    2016-09-01

    Pregnant women often use herbal medicines to alleviate symptoms of pregnancy. The active phytochemicals eugenol (from holy basil) and α-bisabolol (from chamomile) are recommended to promote calmness and reduce stress. There is evidence that both eugenol and α-bisabolol possess pro-apoptotic and anti-proliferative effects and induce reactive oxygen species. The potential effect was examined by monitoring cardiomyocyte contractile activity (differentiation), cell activity, protein content and ROS production for mouse D3 embryonic stem cell and ‎chick embryonic micromass culture. The results showed that eugenol (0.01-80μM) demonstrated effects on cell activity (both systems) and ROS production (stem cell system only), as well as decreasing the contractile activity and protein content at high concentrations in both systems. Additionally, α-bisabolol (0.01-80μM) at high concentrations decreased the contractile activity and cell activity and in the stem cell system induced ROS production and decreased protein content. The results suggest only low concentrations should be ingested in pregnancy.‎.

  12. Hypoxia during embryonic development increases energy metabolism in normoxic juvenile chicks.

    Science.gov (United States)

    Amaral-Silva, Lara do; Scarpellini, Carolina da S; Toro-Velasquez, Paula Andrea; Fernandes, Marcia H M R; Gargaglioni, Luciane H; Bícego, Kênia C

    2017-03-07

    Environmental changes during perinatal development can affect the postnatal life. In this sense, chicken embryos that experience low levels of O2 over a specific phase of incubation can have their tissue growth reduced and the ventilatory response to hypoxia blunted, at least until hatching. Additionally, exposure to low level of O2 after birth reduces the thermogenesis as well. In the present study, we tested the hypothesis that hypoxia over the third week of incubation affects the thermoregulation of juvenile chicks at an age when thermogenesis is already expected to be well-developed. To this end, we measured body temperature (Tb) and oxygen consumption (V̇02) under acute hypoxia or different ambient temperatures (Ta) of 1 and 10day-old chicks that have been exposed to 21% O2 for entire incubation (Nx) or to 15% O2 in the last week of incubation (Hx). We also assessed the thermal preference under normoxia or acute hypoxia of the older chicks from both incubation groups in a thermocline. Hypoxia over incubation reduced growth but did not affect the cold-induced thermogenesis in hatchlings. Regarding the juvenile Hx, present data indicate a catch up growth with higher resting V̇02, a thermal preference for warmer Tas and a possible higher thermal conductance. In conclusion, our results show that hypoxia over the third week of incubation can affect the thermoregulation at least until 10days after hatch in chickens.

  13. K channel kinetics during the spontaneous heart beat in embryonic chick ventricle cells.

    OpenAIRE

    Mazzanti, M.; DeFelice, L J

    1988-01-01

    By averaging the current that passes through cell-attached patches on beating heart cells, while measuring action potentials with a whole-cell electrode, we were able to study K channels during beating. In 7-d chick ventricle in 1.3 mM K physiological solutions at room temperature, delayed-rectifier channels have three linear conductance states: 60, 30, and 15 pS. The 60 and 15 pS conductances can exist alone, but all three states may appear in the same patch as interconverting conductance le...

  14. Direct localised measurement of electrical resistivity profile in rat and embryonic chick retinas using a microprobe

    Directory of Open Access Journals (Sweden)

    Harald van Lintel

    2010-01-01

    Full Text Available We report an alternative technique to perform a direct and local measurement of electrical resistivities in a layered retinal tissue. Information on resistivity changes along the depth in a retina is important for modelling retinal stimulation by retinal prostheses. Existing techniques for resistivity-depth profiling have the drawbacks of a complicated experimental setup, a less localised resistivity probing and/or lower stability for measurements. We employed a flexible microprobe to measure local resistivity with bipolar impedance spectroscopy at various depths in isolated rat and chick embryo retinas for the first time. Small electrode spacing permitted high resolution measurements and the probe flexibility contributed to stable resistivity profiling. The resistivity was directly calculated based on the resistive part of the impedance measured with the Peak Resistance Frequency (PRF methodology. The resistivity-depth profiles for both rat and chick embryo models are in accordance with previous mammalian and avian studies in literature. We demonstrate that the measured resistivity at each depth has its own PRF signature. Resistivity profiles obtained with our setup provide the basis for the construction of an electric model of the retina. This model can be used to predict variations in parameters related to retinal stimulation and especially in the design and optimisation of efficient retinal implants.

  15. Influence of substitution at C/sub 24/ on the calcium-binding protein-stimulating activity of vitamin D metabolites in chick embryonic duodenum

    Energy Technology Data Exchange (ETDEWEB)

    Parkes, C.O. (Univ. of British Columbia, Vancouver); Deluca, H.F.

    1979-01-01

    The production of calcium-binding protein, in vitro, by embryonic chick duodenum has been used to assess the potency of vitamin D compounds. The introduction of an hydroxyl on 1-, 25-, or 24R-position enhanced biological activity while the introduction of both 1..cap alpha..- and 25-hydroxyls produced maximal activity. However, 24R-hydroxylation of 1,25-dihydroxyvitamin D/sub 3/ diminished activity. The vitamin D/sub 2/ side chain on 25-hydroxy-vitamin D or 1,25-dihydroxyvitamin D did not greatly diminish activity in contrast to the fact that the vitamin D/sub 2/ compounds are 10% as active as the vitamin D/sub 3/ compounds in vivo in the chick. These results support the idea that the target organs of the chick do not discriminate against the vitamin D/sub 2/ side chain and that the discrimination in this species is at the level of metabolism.

  16. Dynamic expression of Notch-dependent neurogenic markers in the chick embryonic nervous system

    Directory of Open Access Journals (Sweden)

    Leslie eRatié

    2014-12-01

    Full Text Available The establishment of a functional nervous system requires a highly orchestrated process of neural proliferation and differentiation. The evolutionary conserved Notch signalling pathway is a key regulator of this process, regulating bHLH transcriptional repressors and proneural genes. However little is known about downstream Notch targets and subsequently genes required for neuronal specification.In this report, the expression pattern of Tagln3, Chga and Cntn2 was described in detail during early chick embryogenesis. Expression of these genes was largely restricted to the nervous system including the early axon scaffold populations, cranial ganglia and spinal motor neurons. Their temporal and spatial expression were compared with the neuronal markers Nhlh1, Stmn2 and HuC/D. We show that Tagln3 is an early marker for postmitotic neurons whereas Chga and Cntn2 are expressed in mature neurons. We demonstrate that inhibition of Notch signalling during spinal cord neurogenesis enhances expression of these markers. This data demonstrates that Tagln3, Chga and Cntn2 represent strong new candidates to contribute to the sequential progression of vertebrate neurogenesis.

  17. Electroporation of proviral RCAS DNA alters gene expression in the embryonic chick hindbrain.

    Science.gov (United States)

    Hermann, Petra M; Logan, C Cairine

    2003-11-01

    Gene transfer by means of electroporation is an effective method for delivering DNA into cells. Expression vectors encoding green fluorescent protein (GFP) are routinely used as a control for this technique and are also regularly used to indirectly or directly monitor the expression of introduced transgenes. However, recent studies suggest that GFP may have nonspecific and/or cytotoxic side effects. In this study, we investigated the effects of enhanced GFP (EGFP) expression delivered by means of electroporation of proviral RCASBP(B)-EGFP DNA on gene expression in the hindbrain of chick embryos. We examined, via whole-mount in situ hybridization, the expression of a number of transcription factors. We found that Tlx-1 was ectopically expressed following electroporation of proviral RCASBP(B)-EGFP DNA. In contrast, the number of cells expressing Tlx-3, Phox2a, and Phox2b were reduced. Intriguingly, these effects could be mimicked by electroporation of wild-type proviral RCASBP(B) DNA (i.e., lacking the GFP insert). However, neither delivery of the EGFP transgene by means of viral infection nor electroporation alone yielded aberrant expression patterns. Together our data indicate that alterations of gene expression patterns are not directly due to the expression of EGFP but instead reflect a confounding effect of electroporating proviral DNA.

  18. Elastic extracellular matrix of the embryonic chick heart: an immunohistological study using laser confocal microscopy.

    Science.gov (United States)

    Hurle, J M; Kitten, G T; Sakai, L Y; Volpin, D; Solursh, M

    1994-08-01

    The "elastic matrix" constitutes a specialized component of the extracellular matrix which confers resiliency to tissues and organs subjected to repeated deformations. The role of the elastic matrix in living organisms appears to be of key importance since diseases characterized by expression of defective inherited genes which encode components of the elastic matrix lead to premature death. While the elastic matrix of adult organs has received a great deal of attention, little is known about when it first appears in embryonic tissues or its possible role in developing organs. In the present study we have performed an immunohistochemical study of the distribution of elastin and three additional components often associated with elastic matrices in adult tissues (i.e., fibrillin, emilin, and type VI collagen) during the development of the chicken embryonic heart. The three-dimensional arrangement of these components was established through the observation of whole-amount specimens with scanning laser confocal microscopy. Our results revealed three different periods of heart development regarding the composition of the elastic matrix. Prior to stage 21 the embryonic heart lacks elastin but exhibits a matrix scaffold of fibrillin and emilin associated with the endocardium and the developing cardiac jelly. Between stages 22 and 29 the heart shows a transient elastic scaffold in the outflow tract which contains elastin, fibrillin, and emilin. Elastin-positive fibrillar material is also observed during these stages in the base of the atrioventricular cushion adjacent to the myocardial wall. In addition, emilin-positive material appears to be associated with the zones of formation of ventricular trabeculae. Collagen type VI was not detected during these early stages. From stage 30 to stage 40 a progressive modification of the pattern of distribution of elastin, fibrillin, emilin, and collagen type VI is observed in association with the formation of the definitive four

  19. Production of a monoclonal antibody by in vitro immunization that recognizes a native chondroitin sulfate epitope in the embryonic chick limb and heart.

    Science.gov (United States)

    Capehart, A A; Wienecke, M M; Kitten, G T; Solursh, M; Krug, E L

    1997-11-01

    We report the production of a monoclonal antibody (d1C4) by in vitro immunization that has immunoreactivity with a native chondroitin sulfate epitope in embryonic chick limb and heart. Murine lymphocytes were stimulated by direct exposure to unfixed, unsolubilized precartilage mesenchymal aggregates in high-density micromass culture derived from Stage 22-23 chick limb buds. Specificity of d1C4 reactivity was demonstrated by sensitivity of immunohistochemical staining to pretreatment with chondroitinase ABC or AC, preferential immunoreactivity with chondroitin-6-sulfate glycosaminoglycan (CS-C GAG) in ELISA, and competition of immunohistochemical staining with CS-C GAG. Immunohistochemical analysis of the expression of the d1C4 epitope revealed a striking localization of immunoreactivity in the extracellular matrix (ECM) of precartilage aggregates of chick limb mesenchyme in high-density micromass culture by 16 hr and the prechondrogenic limb core at Stage 23 in vivo. Immunoreactivity in both cultured limb mesenchyme and the embryonic limb continued through differentiation of prechondrogenic condensations into cartilage tissue. In the developing chick heart, d1C4 staining was found throughout the ECM of atrioventricular cushion tissue by Stage 25, but was localized to mesenchyme adjacent to the myocardium in the outflow tract cushions. There was an abrupt demarcation between d1C4-reactive intracardiac mesenchyme and unreactive extracardiac mesenchyme of the dorsal mesocardium in the Stage 22 embryo. This study demonstrates the efficacy of in vitro immunization of lymphocytes for the production of MAbs to native ECM constituents, such as CS-GAGs. Immunohistochemical data utilizing d1C4 suggest that CS-GAGs bearing this epitope may be important in early morphogenetic events leading to cartilage differentiation in the limb and valvuloseptal morphogenesis in the heart.

  20. Developmental cues for bone formation from parathyroid hormone and parathyroid hormone-related protein in an ex vivo organotypic culture system of embryonic chick femora.

    Science.gov (United States)

    Smith, Emma L; Kanczler, Janos M; Roberts, Carol A; Oreffo, Richard O C

    2012-12-01

    Enhancement and application of our understanding of skeletal developmental biology is critical to developing tissue engineering approaches to bone repair. We propose that use of the developing embryonic femur as a model to further understand skeletogenesis, and the effects of key differentiation agents, will aid our understanding of the developing bone niche and inform bone reparation. We have used a three-dimensional organotypic culture system of embryonic chick femora to investigate the effects of two key skeletal differentiation agents, parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP), on bone and cartilage development, using a combination of microcomputed tomography and histological analysis to assess tissue formation and structure, and cellular behavior. Stimulation of embryonic day 11 (E11) organotypic femur cultures with PTH and PTHrP initiated osteogenesis. Bone formation was enhanced, with increased collagen I and STRO-1 expression, and cartilage was reduced, with decreased chondrocyte proliferation, collagen II expression, and glycosaminoglycan levels. This study demonstrates the successful use of organotypic chick femur cultures as a model for bone development, evidenced by the ability of exogenous bioactive molecules to differentially modulate bone and cartilage formation. The organotypic model outlined provides a tool for analyzing key temporal stages of bone and cartilage development, providing a paradigm for translation of bone development to improve scaffolds and skeletal stem cell treatments for skeletal regenerative medicine.

  1. Approach to quantify two-dimensional strain of chick embryonic heart in early stage based on spectral domain optical coherence tomography

    Science.gov (United States)

    Zhao, Yuqian; Dou, Shidan; Zhu, Wenlong; Wang, Yi; Xu, Tao; Wang, Fengwen; Ma, Zhenhe

    2015-03-01

    The heart undergoes remarkable changes during embryonic development due to genetic programming and epigenetic influences, in which mechanical loads is a key factor. As embryonic research development, an important goal is to develop mathematical models that describe the influence of mechanics on embryonic heart development. However, basic parameters for the modeling are difficult to acquire since the embryonic heart is tiny and beating fast in the early stages. Optical coherence tomography (OCT) technique provides depth-resolved image with high resolution and high acquisition speed in a noninvasive manner. In this paper, we performed 4D[(x,y,z) + t] scan on the outflow tract (OFT) of the chick embryonic heart at stage of HH18(~ 3 days of incubation) in vivo using spectral domain OCT (SDOCT). Parameters such as displacement and geometrical size of the OFT were extracted from the structural images of the SDOCT. Two-dimensional strain vector were solved using strain-displacement relations in curvilinear cylindrical coordinates based on kinetic theory of elasticity. Based on the geometrical size and other initial conditions, two-dimensional elasticity finite element model of the OFT myocardial wall deformation were established and then solved by direct frequency response method. Comparison between experimental data and simulation result shows the utility of the finite element models. Our results demonstrate that mathematical modeling based on parameters provided by SDOCT is a useful approach for studying cardiac development in early stage.

  2. Rotationally acquired 4D-optical coherence tomography of embryonic chick hearts using retrospective gating on the common central A-scan

    DEFF Research Database (Denmark)

    Thommes, Jan; Happel, Christoph M.; Thrane, Lars

    2010-01-01

    In vivo analysis of cardiac physiology and non-invasive imaging of the beating early embryonic heart in 2 and 3D remain a challenge in cardiovascular development research. 3D-imaging of the beating heart relies on gating of the acquired images according to the cardiac cycle. Mostly ECG triggering...... is used for this purpose, e.g. in MRT or CT of human hearts. For visualization of embryonic chick hearts with high-resolution optical coherence tomography (OCT), a gating trigger generated by laser Doppler velocimetry has been successfully demonstrated (1). But this takes time and adds to system...... complexity. More recently, retrospective gating technologies were described (2; 3). In these studies, a time series of 2D images at several positions along the heart volume was used to produce a time sequence of 3D volumes of the beating heart. Rearrangement and validation of the asynchronously acquired...

  3. Rotationally acquired four-dimensional optical coherence tomography of embryonic chick hearts using retrospective gating on the common central A-scan

    DEFF Research Database (Denmark)

    Happel, Christoph M.; Thommes, Jan; Thrane, Lars;

    2011-01-01

    We introduce a new method of rotational image acquisition for four-dimensional (4D) optical coherence tomography (OCT) of beating embryonic chick hearts. The rotational axis and the central A-scan of the OCT are identical. An out-of-phase image sequence covering multiple heartbeats is acquired...... at every angle of an incremental rotation of the deflection mirrors of the OCT system. Image acquisition is accomplished after a rotation of 180◦. Comparison of a displayed live M-mode of the central A-scan with a reference M-mode allows instant detection of translational movements of the embryo....... For calculation of 4D data sets, we apply an imagebased retrospective gating algorithm using the phase information of the common central A-scan present in all acquired images. This leads to cylindrical three-dimensional data sets for every time step of the cardiac cycle that can be used for 4D visualization...

  4. In vivo functional imaging of blood flow and wall strain rate in outflow tract of embryonic chick heart using ultrafast spectral domain optical coherence tomography

    Science.gov (United States)

    Li, Peng; Yin, Xin; Shi, Liang; Rugonyi, Sandra; Wang, Ruikang K.

    2012-09-01

    During cardiac development, the cardiac wall and flowing blood are two important cardiac tissues that constantly interact with each other. This dynamic interaction defines appropriate biomechanical environment to which the embryonic heart is exposed. Quantitative assessment of the dynamic parameters of wall tissues and blood flow is required to further our understanding of cardiac development. We report the use of an ultrafast 1310-nm dual-camera spectral domain optical coherence tomography (SDOCT) system to characterize/image, in parallel, the dynamic radial strain rate of the myocardial wall and the Doppler velocity of the underlying flowing blood within an in vivo beating chick embryo. The OCT system operates at 184-kHz line scan rate, providing the flexibility of imaging the fast blood flow and the slow tissue deformation within one scan. The ability to simultaneously characterize tissue motion and blood flow provides a useful approach to better understand cardiac dynamics during early developmental stages.

  5. Diglyceride kinase activity of microtubules. Characterization and comparison with the protein kinase and ATPase activities associated with vinblastine-isolated tubulin of chick embryonic muscles.

    Science.gov (United States)

    Daleo, G R; Piras, M M; Piras, R

    1976-09-15

    Vinblastine-isolated microtubule protein from chick embryonic muscles has an enzymatic activity which catalyzes the formation of phosphatidic acid from diglycerides and ATP. The pH optimum (6.4), sedimentation on sucrose gradients (Mr = 85 000), and sensitivity to ions of this diglyceride kinase activity are different to those of a similar enzymatic activity present in 150 000 X g supernatants of chick embryonic muscle homogenates, suggesting that it is a different species which is associated specifically with the microtubules. The reaction requires a divalent ion (e.g. 0.4 mM Mg2+ gives half-maximal stimulation), and GTP can replace ATP rather effectively, especially at nucleotide concentrations lower than 50 muM. The sedimentation of the diglyceride kinase on sucrose gradients coincides with that of the microtubules-associated protein kinase (Mr = 75 000); the heat-stability and sensivitity to proteolysis of both activities are also very similar. Stimulation of one reaction by the addition of the corresponding exogenous substrate does not impair the phosphorylation of the other, and no radioactivity is lost from phosphatidic acid or the protein moiety upon incubation of pre-labelled microtubules with a large excess of unlabelled ATP or GTP. In addition to diglyceride and protein kinase activities (0.2 and 0.3 nmol 32P-transferred X min-1 X mg-1 microtubular protein, respectively), microtubules also contain an associated ATPase (2.8 nmol X min-1 X mg-1), which requires either Mg2+ or Ca2+, can hydrolyze GTP quite effectively, and sediments with a molecular weight of 95000. The results obtained are discussed in connection with the possible relationships existing among these enzymatic activities, as well as their probable role in microtubular functions.

  6. Lithium carbonate teratogenic effects in chick cardiomyocyte micromass system and mouse embryonic stem cell derived cardiomyocyte--possible protective role of myo-inositol.

    Science.gov (United States)

    Qureshi, W M Shaikh; Latif, M L; Parker, T L; Pratten, M K

    2014-07-01

    The drug lithium carbonate (Li2CO3) use during pregnancy increases the possibility of cardiovascular anomalies. The earlier studies confirm its phosphatidylinositol cycle (PI) inhibition and Wnt pathways mimicking properties, which might contribute to its teratogenic effects. In this study the toxic effects of Li2CO3 in chick embryonic cardiomyocyte micromass system (MM) and embryonic stem cell derived cardiomyocyte (ESDC) were evaluated, with possible protective role of myo-inositol. In MM system the Li2CO3 did not alter the toxicity estimation endpoints, whereas in ESDC system the cardiomyocytes contractile activity stopped at 1500 μM and above with significant increase in total cellular protein contents. In ESDC system when myo-inositol was added along with Li2CO3 to continue PI cycle, the contractile activity was recovered with decreased protein content. The lithium toxic effects depend on the role of PI cycle at particular stage of cardiogenesis, while relation between myo-inositol and reduced cellular protein contents remains unknown.

  7. Reaggregation of human, chick, and human embryonic brain cells. Factors influencing the formation of a histiotypic unit.

    Science.gov (United States)

    Lodin, Z; Fleischmannová, V; Hájková, B; Faltin, J; Hartman, J

    1981-01-01

    1. Aggregation of embryo human, mouse, and chick brain cells was studied. The optimum age interval of donors from different species was determined. 2. The significance of different dissociation procedures (mild trypsinisation followed by sieving, trypsinisation + DNA digestion, mechanical dissociation in 1 or 2 steps, and Ca2+ chelation by EGTA) for the rate of aggregation was estimated. A significant reduction of aggregation was observed after one step mechanical dissociation. Nonspecific adhesion of cells on DNA molecules was found only during the first stages of aggregation. 3. The curve of aggregation kinetics follows the curve of floculation kinetics. 90% free cells disappear from the medium after 2 h of aggregation and a large number of microaggregates are formed which condense after 20 to 24 h into compact aggregates. The time course of aggregation was similar for all cells dissociated by different means. Small differences in the rate of aggregation, caused by dissociation procedures, were apparent only during the first stages of aggregation. 4. The histiotypic unit formed by aggregation of human, mouse, and chick embryo brain cells exhibits some common and some specific features. During aggregation a multiple structural reconstruction takes place and a limited number of cells are exchanged or sorted out from aggregates into the medium. 5. The structural organisation of aggregates from differently dissociated cells differs in several aspects. This indicates that membrane surface structures are influenced differently by dissociation and behave differently during distinct stages of aggregation.

  8. Optical mapping reveals developmental dynamics of Mg2+-/APV-sensitive components of glossopharyngeal glutamatergic EPSPs in the embryonic chick NTS.

    Science.gov (United States)

    Sato, Katsushige; Momose-Sato, Yoko

    2004-10-01

    To examine whether there are any differences in functional organization between the glossopharyngeal nerve (N. IX)- and vagus nerve (N. X)-projecting areas in the nucleus of the tractus solitarius (NTS), we performed optical recording of neural responses evoked by N. IX stimulation in 5- to 9-day-old embryonic chick brain stem preparations and compared the results with those in our previous studies concerning the N. X-related NTS. First, we investigated DL-2-amino-5-phosphonovaleric acid (APV)/Mg2+ sensitivity of the glutamatergic excitatory postsynaptic potentials (EPSPs) in the N. IX-related NTS. In 7- to 9-day-old preparations, we found regional differences in the degree of both the APV-induced reduction and Mg2+-free-induced enhancement of the EPSPs. We constructed developmental maps of spatial patterns of the APV- and Mg2+-sensitive components and showed that functional expression of the N-methyl-D-aspartate (NMDA) receptor dynamically changed during development. Second, we studied initial expression of synaptic functions in the N. IX-related NTS. In 6-day-old preparations, although action potentials alone were usually detected in normal Ringer solution, small EPSPs were elicited in a Mg2+-free solution. This result suggests that the NMDA receptor-mediated synaptic function is latently generated in the N. IX-related NTS at the 6-day-old embryonic stage and that external Mg2+ regulates the onset of synaptic functions. Developmental patterns of APV/Mg2+ sensitivity and the stage of initial expression of the glossopharyngeal EPSP were similar to those of the N. X, suggesting that the developmental sequence of the synaptic function in the NTS is the same for the N. IX- and N. X-related NTS.

  9. Assessment of strain and strain rate in embryonic chick heart in vivo using tissue Doppler optical coherence tomography

    Science.gov (United States)

    Li, Peng; Liu, Aiping; Shi, Liang; Yin, Xin; Rugonyi, Sandra; Wang, Ruikang K.

    2011-11-01

    We present a method to assess the in vivo radial strain and strain rate of the myocardial wall, which is of great importance to understand the biomechanics of cardiac development, using tissue Doppler optical coherence tomography (tissue-DOCT). Combining the structure and velocity information acquired from tissue-DOCT, the velocity distribution in the myocardial wall is plotted, from which the radial strain and strain rate are evaluated. The results demonstrate that tissue-DOCT can be used as a useful tool to describe tissue deformation, especially, the biomechanical characteristics of the embryonic heart.

  10. In vivo functional imaging of embryonic chick heart using ultrafast 1310nm-band spectral domain optical coherence tomography

    Science.gov (United States)

    Li, Peng; Yin, Xin; Wang, Ruikang K.

    2013-02-01

    During the cardiac development, the cardiac wall and the blood flow actively interact with each other, and determine the biomechanical environment to which the embryonic heart exposes. Employing an ultrafast 1310nm-band dual-camera spectral domain optical coherence tomography (SDOCT), the radial strain rate of the myocardial wall can be extracted with high signal-to-noise ratio, at the same time the Doppler velocity of the blood flow can also be displayed. The ability to simultaneously characterize these two cardiac tissues provides a powerful approach to better understand the interaction between the cardiac wall and the blood flow, which is important to the investigation of cardiac development.

  11. Fractal analysis of extra-embryonic vessels of chick embryos under the effect of glucosamine and chondroitin sulfates.

    Science.gov (United States)

    de Souza Lins Borba, Fernanda Katharine; Felix, Giovanni Loos Queiroz; Costa, Edbhergue Ventura Lola; Silva, Lisie; Dias, Paulo Fernando; de Albuquerque Nogueira, Romildo

    2016-05-01

    Like heparan sulfate proteoglycans, some monosaccharides and glycosaminoglycans, such as sulfated glucosamine (GS) and chondroitin (CS), integrate the vascular extracellular matrix and may influence vascular endothelial cell growth. To assess the effects of these substances on blood vessel formation, we used the chick yolk sac membrane (YSM) model and fractal geometry quantification, which provided an objective in vivo method for testing potential agents that promote vasculogenesis and angiogenesis. An image processing method was developed to evaluate YSM capillary vessels after they were implanted in a methylcellulose disk of GS or CS at a concentration between 0.001-0.1mg/disk (performed on 2-day old embryos). This method resulted in a binary image of the microvascular network (white vessels on a black background). Fractal box-counting (DBC) and information (DINF) dimensions were used to quantify the activity of GS and CS in vasculogenesis and angiogenesis. YSM treated with GS (0.001-0.1mg) and CS (0.03-0.1mg) showed an increase in fractal dimensions that corresponded to vitelline vessel growth compared to the control group (vehicle), with GS displaying higher fractal dimension values.

  12. Pulsating stars

    CERN Document Server

    Catelan, M?rcio

    2014-01-01

    The most recent and comprehensive book on pulsating stars which ties the observations to our present understanding of stellar pulsation and evolution theory.  Written by experienced researchers and authors in the field, this book includes the latest observational results and is valuable reading for astronomers, graduate students, nuclear physicists and high energy physicists.

  13. Regularity of beating of small clusters of embryonic chick ventricular heart-cells: experiment vs. stochastic single-channel population model

    Science.gov (United States)

    Krogh-Madsen, Trine; Kold Taylor, Louise; Skriver, Anne D.; Schaffer, Peter; Guevara, Michael R.

    2017-09-01

    The transmembrane potential is recorded from small isopotential clusters of 2-4 embryonic chick ventricular cells spontaneously generating action potentials. We analyze the cycle-to-cycle fluctuations in the time between successive action potentials (the interbeat interval or IBI). We also convert an existing model of electrical activity in the cluster, which is formulated as a Hodgkin-Huxley-like deterministic system of nonlinear ordinary differential equations describing five individual ionic currents, into a stochastic model consisting of a population of ˜20 000 independently and randomly gating ionic channels, with the randomness being set by a real physical stochastic process (radio static). This stochastic model, implemented using the Clay-DeFelice algorithm, reproduces the fluctuations seen experimentally: e.g., the coefficient of variation (standard deviation/mean) of IBI is 4.3% in the model vs. the 3.9% average value of the 17 clusters studied. The model also replicates all but one of several other quantitative measures of the experimental results, including the power spectrum and correlation integral of the voltage, as well as the histogram, Poincaré plot, serial correlation coefficients, power spectrum, detrended fluctuation analysis, approximate entropy, and sample entropy of IBI. The channel noise from one particular ionic current (IKs), which has channel kinetics that are relatively slow compared to that of the other currents, makes the major contribution to the fluctuations in IBI. Reproduction of the experimental coefficient of variation of IBI by adding a Gaussian white noise-current into the deterministic model necessitates using an unrealistically high noise-current amplitude. Indeed, a major implication of the modelling results is that, given the wide range of time-scales over which the various species of channels open and close, only a cell-specific stochastic model that is formulated taking into consideration the widely different ranges in

  14. An analysis of the growth of the retinal cell population in embryonic chicks yielding proliferative ratios, numbers of proliferative and non-proliferative cells and cell-cycle times for successive generations of cell cycles.

    Science.gov (United States)

    Morris, V B; Cowan, R

    1995-07-01

    Growth curves of the retinal cell population of embryonic chicks were fitted by a branching-process model of cell population growth, thereby estimating the proliferative ratios and mean cell-cycle times of the generations of cell cycles that underlie retinal growth. The proliferative ratio determines the proportion of cells that divides in the next generation, so the numbers of proliferative and non-proliferative cells in each generation of cell cycles were obtained. The mean cell-cycle times determine the times over which the generations are extant. Assuming growth starts from one cell in generation 0, the proliferative cells reach 3.6 x 10(6) and the non-proliferative cells reach 1.1 x 10(6) by generation 23. The next four generations increase the proliferative cell numbers to 13.9 x 10(6) and produce 20.1 x 10(6) non-proliferative cells. In the next five generations in the end phase of growth, non-proliferative cells are produced in large numbers at an average of 13.9 x 10(6) cells per generation as the retinal lineages are completed. The retinal cell population reaches a maximum estimated here at 98.2 x 10(6) cells. The mean cell-cycle time estimates range between 6.8 and 10.1 h in generations before the end phase of growth and between 10.6 and 17.2 h in generations in the end phase. The retinal cell population growth is limited by the depletion of the proliferative cell population that the production of non-proliferative cells entails. The proliferative ratios and the cell-cycle-time distribution parameters are the likely determinants of retinal growth rates. The results are discussed in relation to other results of spatial and temporal patterns of the cessation of cell cycling in the embryonic chick retina.

  15. Measurement of wall strain in embryonic chick heart by sp ectral domain optical coherence tomography%基于光学相干层析成像的早期鸡胚心脏径向应变测量∗

    Institute of Scientific and Technical Information of China (English)

    马振鹤; 窦世丹; 马毓姝; 刘健; 赵玉倩; 刘江红; 吕江涛; 王毅

    2016-01-01

    During cardiac development, the growth, remodeling and morphogenesis of embryonic hearts are closely linked to hemodynamic forces. An understanding of the interaction mechanism between hemodynamic forces and heart devel-opment is important for the early diagnosis and treatment of various congenital defects. The myocardial wall strain (MWS) in embryonic heart is a critical parameter for quantifying the mechanical properties of cardiac tissues. Here, we focus on the radial strain which is defined as the change of the myocardial wall thickness. An effective measurement of MWS is conductive to studies of embryonic heart development. Chick embryo is a popular animal model used for studing the cardiac development due to the similarity of cardiac development between the human heart and the chick heart at early developmental stages and its easy access. Although various imaging methods have been proposed, there still remain significant challenges to imaging of early stage chick embryo heart because it is small in size and beats fast. Optical coherence tomography (OCT) is a non-contact three-dimensional imaging modality with high spatial and temporal resolution which has been widely used for imaging the biological tissue. In this paper, we describe a method to measure in vivo MWS of chicken embryonic hearts with a high speed spectral domain OCT(SDOCT) system worked at 1310 nm. We perform four-dimensional (4D) (x, y, z, t) scanning on the outflow tract (OFT) of chick embryonic hearts in a non-gated way. The transient states of the OFT are extracted from the 4D data by using the beating synchronization algorithm. The OFT center line can be achieved by image processing. Assuming that the blood flow is parallel to the center line in the blood vessel, we calculate the Doppler angle of blood flow from the OFT center line. In a certain OFT cross-section, the OFT myocardial wall (inner and external borders) is segmented from the OCT images with a semi-automatic boundary

  16. Expression of neuronal guidance factor Slit2 in the spinal cord of chick embryonic development%神经生长导向因子Slit2在鸡胚脊髓发育中的表达

    Institute of Scientific and Technical Information of China (English)

    伍思琪; 张玉英; 吴婷; 王丽京; 韩哲; 杨雪松

    2012-01-01

    目的 观察神经生长导向因子Slit2在鸡胚神经管和脊髓不同发育时期的表达变化.方法 用免疫组织化学方法检测Slit2蛋白在鸡胚原肠期(HH6-HH10)神经管和第3d-17d(E3-E17期)脊髓中的表达和分布情况.结果 Slit2蛋白在鸡胚神经管和脊髓不同发育时期均有阳性表达,在脊髓中线结构区呈优势表达,在第9d(E9期)脊髓中线底板处表达最明显,第11d后Slit2蛋白阳性表达逐渐减弱并呈散在分布.结论 神经生长导向因子Slit2在鸡胚各发育时期神经管和脊髓的阳性表达呈动态变化.Slit2蛋白在脊髓发育过程起着重要作用.%Objective To explore the expression of neuronal guidance factor Slit2 in the neural tube and spinal cord of chick embryonic development. Method The protein expression pattern of Slit2 was detected in the neural tube(HH6-HH10) and spinal cord(3d-17d) using immunohistochemistry. Results Slit 2 positive product was detected in different stages of neural tube and spinal cord of chick embryo, superior in the spinal cord midline of neural floor plate to other regions, especially on 9 day chick embryo, but showed an attenuated and diffused trend after 11 days. Conclusion The expression pattern of neuronal guidance factor Slit2 in the neural tube and spinal cord of chick embryo presented a dynamic change.

  17. Hybrid Pulsators -- Pulsating Stars with Multiple Identities

    CERN Document Server

    Zhou, A -Y

    2015-01-01

    We have carried out a statistic survey on the pulsating variable stars with multiple identities. These stars were identified to exhibit two types of pulsation or multiple light variability types in the literature, and are usually called hybrid pulsators. We extracted the hybrid information based on the Simbad database. Actually, all the variables with multiple identities are retrieved. The survey covers various pulsating stars across the Hertzsprung-Russell diagram. We aim at giving a clue in selecting interesting targets for further observation. Hybrid pulsators are excellent targets for asteroseismology. An important implication of such stars is their potential in advancing the theories of both stellar evolution and pulsation. By presenting the statistics, we address the open questions and prospects regarding current status of hybrid pulsation studies.

  18. The Chick Chorioallantoic Membrane: A Model of Molecular, Structural, and Functional Adaptation to Transepithelial Ion Transport and Barrier Function during Embryonic Development

    Directory of Open Access Journals (Sweden)

    Maria Gabriella Gabrielli

    2010-01-01

    Full Text Available The chick chorioallantoic membrane is a very simple extraembryonic membrane which serves multiple functions during embryo development; it is the site of exchange of respiratory gases, calcium transport from the eggshell, acid-base homeostasis in the embryo, and ion and H2O reabsorption from the allantoic fluid. All these functions are accomplished by its epithelia, the chorionic and the allantoic epithelium, by differentiation of a wide range of structural and molecular peculiarities which make them highly specialized, ion transporting epithelia. Studying the different aspects of such a developmental strategy emphasizes the functional potential of the epithelium and offers an excellent model system to gain insights into questions partly still unresolved.

  19. Biomechanics of the chick embryonic heart outflow tract at HH18 using 4D optical coherence tomography imaging and computational modeling.

    Directory of Open Access Journals (Sweden)

    Aiping Liu

    Full Text Available During developmental stages, biomechanical stimuli on cardiac cells modulate genetic programs, and deviations from normal stimuli can lead to cardiac defects. Therefore, it is important to characterize normal cardiac biomechanical stimuli during early developmental stages. Using the chicken embryo model of cardiac development, we focused on characterizing biomechanical stimuli on the Hamburger-Hamilton (HH 18 chick cardiac outflow tract (OFT, the distal portion of the heart from which a large portion of defects observed in humans originate. To characterize biomechanical stimuli in the OFT, we used a combination of in vivo optical coherence tomography (OCT imaging, physiological measurements and computational fluid dynamics (CFD modeling. We found that, at HH18, the proximal portion of the OFT wall undergoes larger circumferential strains than its distal portion, while the distal portion of the OFT wall undergoes larger wall stresses. Maximal wall shear stresses were generally found on the surface of endocardial cushions, which are protrusions of extracellular matrix onto the OFT lumen that later during development give rise to cardiac septa and valves. The non-uniform spatial and temporal distributions of stresses and strains in the OFT walls provide biomechanical cues to cardiac cells that likely aid in the extensive differential growth and remodeling patterns observed during normal development.

  20. Chick heart invasion assay.

    Science.gov (United States)

    Bracke, Marc E; Parmar, Virinder S; Depass, Anthony L; Stevens, Christian V; Vanhoecke, Barbara W; Mareel, Marc M

    2014-01-01

    Tumors are microecosystems in which a continuous cross talk between cancer cells and host cells decides on the invasive behavior of the tumor cell population as a whole (Mareel et al., Encyclopedia of cancer, San Diego, CA, Academic Press, 1997). Both compartments secrete activating and inhibitory factors that modulate activities such as cell-extracellular matrix (ECM) interaction, cell-cell adhesion, remodeling of the ECM, and cell motility. For this reason, confrontations of cancer cells with a living normal host tissue in organ culture have been introduced by several groups: Wolff and Schneider in France (Wolff and Schneider, C R S Soc Biol (Paris) 151:1291-1292, 1957), Easty and Easty in the United Kingdom (Easty and Easty, Nature 199:1104-1105, 1963), and Schleich in Germany (Schleich et al., J Natl Cancer Inst 56:221-237, 1976). Embryonic chick heart fragments in organ culture maintain many histological features of their tissue of origin: They are composed of myocytes, fibroblasts, and endothelial cells, and their ECM contains fibronectin, laminin, and several collagen types. Moreover, the fragments remain contractile, and this activity allows the monitoring of their functional integrity during organ culture.

  1. Nonlinear pulsation masses

    Energy Technology Data Exchange (ETDEWEB)

    Davis, C.G.

    1990-01-01

    The advent of nonlinear pulsation theory really coincides with the development of the large computers after the second world war. Christy and Stobbie were the first to make use of finite difference techniques on computers to model the bumps'' observed in the classical Cepheid light and velocity curves, the so-called Hertzsprung'' sequence. Following this work a more sophisticated analysis of the light and velocity curves from the models was made by Simon and Davis using Fourier techniques. Recently a simpler amplitude equation formalism has been developed that helps explain this resonance mechanism. The determination of Population I Cepheid masses by nonlinear methods will be discussed. For the lower mass objects, such as RR Lyrae and BL Her. stars, we find general agreement using evolutionary masses and nonlinear pulsation theory. An apparent difficulty of nonlinear pulsation theory occurs in the understanding of double'' mode pulsation, which will also be discussed. Recent studies in nonlinear pulsation theory have dealt with the question of mode selection, period doubling and the trends towards chaotic behavior such as is observed in the transition from W Virginis to RV Tauri-like stars. 10 refs., 1 fig., 2 tabs.

  2. Excitation of Stellar Pulsations

    DEFF Research Database (Denmark)

    Houdek, G.

    2012-01-01

    In this review I present an overview of our current understanding of the physical mechanisms that are responsible for the excitation of pulsations in stars with surface convection zones. These are typically cooler stars such as the δ Scuti stars, and stars supporting solar-like oscillations....

  3. Chick stem cells: Current progress and future prospects

    Science.gov (United States)

    Intarapat, Sittipon; Stern, Claudio D.

    2013-01-01

    Chick embryonic stem cells (cESCs) can be derived from cells obtained from stage X embryos (blastoderm stage); these have the ability to contribute to all somatic lineages in chimaeras, but not to the germ line. However, lines of stem cells that are able to contribute to the germ line can be established from chick primordial germ cells (cPGCs) and embryonic germ cells (cEGCs). This review provides information on avian stem cells, emphasizing different sources of cells and current methods for derivation and culture of pluripotent cells from chick embryos. We also review technologies for isolation and derivation of chicken germ cells and the production of transgenic birds. PMID:24103496

  4. Toxicity of metal mixtures to chick embryos

    Energy Technology Data Exchange (ETDEWEB)

    Birge, W.J.; Roberts, O.W.; Black, J.A.

    1976-09-01

    The toxic effects of mercury/selenium and certain other metal mixtures on the chick embryo are examined to determine whether antagonistic, additive or synergistic interactions occur. White Plymouth Rock chicken eggs were treated by yolk injection with cadmium chloride, mercuric chloride, zinc chloride and sodium selenate. Test aliquots were injected prior to incubation using the needle track procedure. Using a sample size of 200, percent survival was determined as hatchability of experimental eggs/controls. Metal mixtures used included mercury/cadmium, mercury/selenium, mercury/zinc, cadmium/selenium, and cadmium/zinc. Except for mercury/selenium, all other metal mixtures gave actual values that were within 5% of those for additive toxic effects. Actual hatchability frequencies for test concentrations of mercury/selenium indicated a moderate degree of synergism. Results indicate that the strong mercury/selenium synergism which affects embryonic development in the carp does not apply for the chick embryo; that most two-way combinations of cadmium, mercury, selenium and zinc exert purely additive effects on chick hatchability; and that these metal mixtures give no discernible antagonistic interactions which affect survival of chick embryos. (MFB)

  5. Pulsation driving and convection

    Science.gov (United States)

    Antoci, Victoria

    2015-08-01

    Convection in stellar envelopes affects not only the stellar structure, but has a strong impact on different astrophysical processes, such as dynamo-generated magnetic fields, stellar activity and transport of angular momentum. Solar and stellar observations from ground and space have shown that the turbulent convective motion can also drive global oscillations in many type of stars, allowing to study stellar interiors at different evolutionary stages. In this talk I will concentrate on the influence of convection on the driving of stochastic and coherent pulsations across the Hertzsprung-Russell diagram and give an overview of recent studies.

  6. Asteroseismology of Pulsating Stars

    Indian Academy of Sciences (India)

    Santosh Joshi; Yogesh C. Joshi

    2015-03-01

    The success of helioseismology is due to its capability of measuring -mode oscillations in the Sun. This allows us to extract information on the internal structure and rotation of the Sun from the surface to the core. Similarly, asteroseismology is the study of the internal structure of the stars as derived from stellar oscillations. In this review we highlight the progress in the observational asteroseismology, including some basic theoretical aspects. In particular, we discuss our contributions to asteroseismology through the study of chemically peculiar stars under the 'Nainital-Cape Survey' project being conducted at ARIES, Nainital, since 1999. This survey aims to detect new rapidly-pulsating Ap (roAp) stars in the northern hemisphere. We also discuss the contribution of ARIES towards the asteroseismic study of the compact pulsating variables. We comment on the future prospects of our project in the light of the new optical 3.6-m telescope to be installed at Devasthal (ARIES). Finally, we present a preliminary optical design of the high-speed imaging photometers for this telescope.

  7. Development of the endolymphatic sac in chick embryos, with reference to the degradation of otoconia

    Science.gov (United States)

    Yoshihara, T.; Kaname, H.; Narita, N.; Ishii, T.; Igarashi, M.; Fermin, C. D.

    1992-01-01

    The endolymphatic sac of chick embryos (from embryonic day 7 to 1-day-old chicks) was studied light- and electron-microscopically. At stage 30-31 (embryonic day 7-7.5), the epithelial cells of the endolymphatic sac were cuboidal to columnar in shape. Microvilli were relatively well developed. The intercellular space was wide. In the endolymphatic space of the endolymphatic sac, varying shapes and sizes of otoconia-like bodies were often observed. Intracytoplasmic phagosomes containing these bodies were rarely found. After stage 37 (embryonic day 11), otoconia-like bodies in the endolymphatic sac decreased in number and size. They were almost the same as the otoconia in the macular organs, ultrastructurally. These findings indicate that the endolymphatic sac of the chick embryos may possess the function of otoconial degradation and removal of calcium from otoconia.

  8. Penguin chicks benefit from elevated yolk androgen levels under sibling competition.

    Directory of Open Access Journals (Sweden)

    Maud Poisbleau

    Full Text Available Crested penguins (genus Eudyptes have a peculiar hatching pattern, with the first-laid egg (A-egg hatching after the second-laid egg (B-egg and chicks from A-eggs typically having a much lower survival probability. Maternal yolk androgens have been suggested to contribute to the competitive superiority of the B-chick in southern rockhopper penguins Eudyptes chrysocome, given their important role in mediating sibling competition in other species. We therefore increased the yolk androgen levels in freshly-laid eggs and examined the consequences for sibling competition--via effects on embryonic developmental times, chick growth and early survival. We placed one androgen-treated egg and one control egg into each foster nest, matching them for mass, laying date and laying order. The androgen treatment did not significantly affect embryonic developmental times or chick measurements at hatching. However, elevated yolk androgen levels benefitted chick growth in interaction with the number of siblings in a brood. Chicks from androgen-treated eggs had faster growth in the presence of a sibling than chicks from control eggs. Under these circumstances they also had a higher survival probability. Thus maternal androgens appear to reinforce the observed hatching pattern, facilitating brood reduction. This contrasts to most previous studies in other species where yolk androgens have been shown to compensate for the negative consequences of delayed hatching within the brood hierarchy.

  9. Mode selection in pulsating stars

    CERN Document Server

    Smolec, R

    2013-01-01

    In this review we focus on non-linear phenomena in pulsating stars the mode selection and amplitude limitation. Of many linearly excited modes only a fraction is detected in pulsating stars. Which of them and why (the problem of mode selection) and to what amplitude (the problem of amplitude limitation) are intrinsically non-linear and still unsolved problems. Tools for studying these problems are briefly discussed and our understanding of mode selection and amplitude limitation in selected groups of self-excited pulsators is presented. Focus is put on classical pulsators (Cepheids and RR Lyrae stars) and main sequence variables (delta Scuti and beta Cephei stars). Directions of future studies are briefly discussed.

  10. Chick lit, chick magnet, biker chick, hippie chick: metaphorical uses of chick in contemporary american english = Chick lit, chick magnet, biker chick, hippie chick: usos metafóricos de chick no inglês americano contemporâneo

    Directory of Open Access Journals (Sweden)

    Mottin, Lívia Pretto

    2011-01-01

    Full Text Available Metáforas não são apenas uma ferramenta poética ou retórica, mas fazem parte do nosso sistema conceptual (Lakoff and Johnson, 1980 e nos permitem entender determinado aspecto de um conceito em termos de outro. Este artigo tem o objetivo de desvendar como o lexema chick pode ser usado para referir ao universo feminino. Primeiramente, apresento uma revisão bibliográfica sobre metáforas e, então, verifico como o domínio de animais pode ser usado para melhor explicar o comportamento humano. Em seguida, apresento dados coletados no Corpus of Contemporary American English (COCA para identificar e interpretar algumas metáforas de chick através de uma análise baseada em corpus. Em cada subcorpus do COCA, as primeiras 100 linhas de concordâncias aleatórias foram analisadas em contexto a fim de verificar as ocorrências dos usos metafóricos e dos usos literais da palavra de busca. As ocorrências não literais foram examinadas com maior cuidado com o objetivo de verificar o uso metafórico por elas representado, determinar a posição que o lexema pode ocupar em uma frase e verificar que palavras são fortes colocadas de chick. Os resultados mostram que chick é uma metáfora produtiva, usada tanto como substantivo quanto como adjetivo. Além disso, as ocorrências de chick em seu sentido metafórico excedem suas ocorrências em sentido literal

  11. Pulsating Star Mystery Solved

    Science.gov (United States)

    2010-11-01

    By discovering the first double star where a pulsating Cepheid variable and another star pass in front of one another, an international team of astronomers has solved a decades-old mystery. The rare alignment of the orbits of the two stars in the double star system has allowed a measurement of the Cepheid mass with unprecedented accuracy. Up to now astronomers had two incompatible theoretical predictions of Cepheid masses. The new result shows that the prediction from stellar pulsation theory is spot on, while the prediction from stellar evolution theory is at odds with the new observations. The new results, from a team led by Grzegorz Pietrzyński (Universidad de Concepción, Chile, Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Poland), appear in the 25 November 2010 edition of the journal Nature. Grzegorz Pietrzyński introduces this remarkable result: "By using the HARPS instrument on the 3.6-metre telescope at ESO's La Silla Observatory in Chile, along with other telescopes, we have measured the mass of a Cepheid with an accuracy far greater than any earlier estimates. This new result allows us to immediately see which of the two competing theories predicting the masses of Cepheids is correct." Classical Cepheid Variables, usually called just Cepheids, are unstable stars that are larger and much brighter than the Sun [1]. They expand and contract in a regular way, taking anything from a few days to months to complete the cycle. The time taken to brighten and grow fainter again is longer for stars that are more luminous and shorter for the dimmer ones. This remarkably precise relationship makes the study of Cepheids one of the most effective ways to measure the distances to nearby galaxies and from there to map out the scale of the whole Universe [2]. Unfortunately, despite their importance, Cepheids are not fully understood. Predictions of their masses derived from the theory of pulsating stars are 20-30% less than predictions from the theory of the

  12. [Bachelard and the mathematical pulsation].

    Science.gov (United States)

    Guitart, René

    2015-01-01

    The working mathematician knows a specific gesture named « mathematical pulsation », a necessary creative moving in diagrams of thoughts and interpretations of mathematical writings. In this perspective the fact of being an object is definitely undecided, and related to the game of relations. The purpose of this paper today is to construct this pulsation, starting from the epistemology of Bachelard, concerning mathematics as well as mathematical physics. On the way, we recover links between ideas of Bachelard and more recent specific propositions by Gilles Ch-let, Charles Alunni, or René Guitart. Also are used authors like Jacques Lacan, Arthur Koestler, Alfred N. Whitehead, Charles S. Peirce. We conclude that the mathematical work consists with pulsative moving in the space of diagrams; we claim that this view is well compatible with the Bachelard's analysis of scientific knowledge: the intellectual or formal mathematical data preceeds the empirical objects, and in some sense these objects result from the pulsative gestures of the thinkers. So we finish with a categorical scheme of the pulsation.

  13. Yolk hormones influence in ovo chemosensory learning, growth, and feeding behavior in domestic chicks.

    Science.gov (United States)

    Bertin, Aline; Meurisse, Maryse; Arnould, Cécile; Leterrier, Christine; Constantin, Paul; Cornilleau, Fabien; Vaudin, Pascal; Burlot, Thierry; Delaveau, Joel; Rat, Christophe; Calandreau, Ludovic

    2016-03-01

    In this study, we assessed whether prenatal exposure to elevated yolk steroid hormones can influence in ovo chemosensory learning and the behavior of domestic chicks. We simulated a maternal environmental challenge by experimentally enhancing yolk progesterone, testosterone, and estradiol concentrations in hen eggs prior to incubation. The embryos from these hormones-treated eggs (HO) as well as sham embryos (O) that had received the vehicle-only were exposed to the odor of fish oil (menhaden) between embryonic Days 11 and 20. An additional group of control embryos (C) was not exposed to the odor. All chicks were tested following hatching for their feeding preferences between foods that were or were not odorized with the menhaden odor. In the 3-min choice tests, the behavior of O chicks differed significantly according to the type of food whereas C and HO chicks showed no preference between odorized and non-odorized food. Our result suggests weaker response in HO chicks. In addition, HO chicks showed impaired growth and reduced intake of an unfamiliar food on the 24-h time scale compared to controls. Our data suggest that embryonic exposure to increased yolk hormone levels can alter growth, chemosensory learning, and the development of feeding behaviors.

  14. A detailed description of an economical setup for electroporation of chick embryos in ovo.

    Science.gov (United States)

    Borges, R M; Horne, J H; Melo, A; Vidal, J T; Vieceli, F M; Melo, M O; Kanno, T Y N; Fraser, S E; Yan, C Y I

    2013-09-01

    One of the challenges of the postgenomic era is characterizing the function and regulation of specific genes. For various reasons, the early chick embryo can easily be adopted as an in vivo assay of gene function and regulation. The embryos are robust, accessible, easily manipulated, and maintained in the laboratory. Genomic resources centered on vertebrate organisms increase daily. As a consequence of optimization of gene transfer protocols by electroporation, the chick embryo will probably become increasingly popular for reverse genetic analysis. The challenge of establishing chick embryonic electroporation might seem insurmountable to those who are unfamiliar with experimental embryological methods. To minimize the cost, time, and effort required to establish a chick electroporation assay method, we describe and illustrate in great detail the procedures involved in building a low-cost electroporation setup and the basic steps of electroporation.

  15. Embryotoxic effects of crude oil in mallard ducks and chicks

    Science.gov (United States)

    Hoffman, D.J.

    1978-01-01

    Recent studies in this laboratory have revealed that surface applications of microliter amounts of some crude and fuel oils that coat less than 10% of the egg surface reduce hatching considerably in different avian species. Applications of paraffin compounds that coat equal areas of the egg surface do not reduce hatching suggesting that toxicity is due to causes other than asphyxia. In the present study, 1?10 :l of South Louisiana crude oil, an API reference oil, were applied to the surface of fertile mallard (Anas platyrhynchos) and chicken (Gallus gallus) eggs. Early embryolethality was greater in mallard embryos than in chick embryos, but later embryolethality that coincided with the time of rapid outgrowth of the chorioallantoic membrane was more prevalent in chick embryos. The overall incidence of embryolethality was similar in both species. Retardation of growth as reflected by embryonic body weight, crown-rump length, beak length, and general appearance was more pronounced in chick than mallard embryos. Teratogenic defects were more frequent in chick embryos, and incomplete or abnormal ossification of the skull was the most common. External application of equivalent amounts of a mixture of paraffin compounds present in crude oil had virtually no embryotoxic effects in either species, suggesting that other components including aromatic hydrocarbons and organometallics may cause the embryotoxicity.

  16. Pulsational-Pair Instability Supernovae

    CERN Document Server

    Woosley, S E

    2016-01-01

    The final evolution of stars in the mass range 60 - 150 solar masses is explored. Depending upon their mass loss and rotation rates, many of these stars will end their lives as pulsational pair-instability supernovae. Even a non-rotating 70 solar mass star is pulsationally unstable during oxygen shell burning and can power a sub-luminous supernova. Rotation decreases the limit further. For more massive stars, the pulsations are less frequent, span a longer time, and are more powerful. Violent pulsations eject not only any residual low density envelope, but also that fraction of the helium core mass outside about 35 - 50 solar masses. The remaining core of helium and heavy elements continues to evolve, ultimately forming an iron core of about 2.5 solar masses that probably collapses to a black hole. A variety of observational transients result with total durations ranging from days to 10,000 years, and luminosities from 10$^{41}$ to 10$^{44}$ erg s$^{-1}$. Many transients resemble ordinary Type IIp supernovae,...

  17. Chicks like consonant music.

    Science.gov (United States)

    Chiandetti, Cinzia; Vallortigara, Giorgio

    2011-10-01

    The question of whether preference for consonance is rooted in acoustic properties important to the auditory system or is acquired through enculturation has not yet been resolved. Two-month-old infants prefer consonant over dissonant intervals, but it is possible that this preference is rapidly acquired through exposure to music soon after birth or in utero. Controlled-rearing studies with animals can help shed light on this question because such studies allow researchers to distinguish between biological predispositions and learned preferences. In the research reported here, we found that newly hatched domestic chicks show a spontaneous preference for a visual imprinting object associated with consonant sound intervals over an identical object associated with dissonant sound intervals. We propose that preference for harmonic relationships between frequency components may be related to the prominence of harmonic spectra in biological sounds in natural environments.

  18. Developmental changes of Insulin-like growth factors in the liver and muscle of chick embryos.

    Science.gov (United States)

    Liu, Yanli; Guo, Wei; Pu, Zhenyu; Li, Xueyuan; Lei, Xinyu; Yao, Junhu; Yang, Xiaojun

    2016-06-01

    The insulin-like growth factors ( IGFS: ) are synthesized in tissues and play an important role in embryonic development of avian via autocrine/paracrine mechanisms. In the study, mRNA expression of IGFs were detected by real-time PCR in the muscle and liver from d 10 to 20 of chick embryo ( E10: to E20: ). Methylation of IGF1 promoter in the muscle was analyzed by bisulfite sequencing PCR as well as IGF2 promoter in the liver. These results showed that there was obviously IGF1 expression in liver at E19 and E20. The higher IGF1 expression in muscle was found during E15 to E18 with the peak on E17, and then declined. Correspondingly, the lowest methylation level of IGF1 promoter was detectable on the same embryonic d 17. Expression of IGF2 in muscle increased gradually during embryonic growth and showed higher level in the later stages (E17 to E20) when IGF1 expression began to decrease. IGF2 expression in liver reached the first peak on E14, then declined but gradually elevated from E17. IGF2 promoter methylation in liver showed gradual decline on d 12, 15, 17 and 19 of incubation, meanwhile IGF2 expression of liver increased gradually. These results suggested that IGF1 and IGF2 might separately be more important for muscle and liver growth in chick embryonic development. Variation of IGFs expression during the incubation might be concerned with the methylation of gene promoter. The profile of IGFs expression in chick embryonic tissues may be meaningful for understanding organ growth and embryonic development in chick. © 2016 Poultry Science Association Inc.

  19. Tissue distribution of cells derived from the area opaca in heterospecific quail-chick blastodermal chimeras.

    Science.gov (United States)

    Karagenç, Levent; Sandikci, Mustafa

    2010-01-01

    The objective of the current study was to determine the tissue distribution of cells derived from the area opaca in heterospecific quail-chick blastodermal chimeras. Quail-chick chimeras were constructed by transferring dissociated cells from the area opaca of the stage X-XII (EG&K) quail embryo into the subgerminal cavity of the unincubated chick blastoderm. The distribution of quail cells in embryonic as well as extra-embryonic tissues of the recipient embryo were examined using the QCPN monoclonal antibody after 6 days of incubation in serial sections taken at 100-mum intervals. Data gathered in the present study demonstrated that, when introduced into the subgerminal cavity of a recipient embryo, cells of the area opaca are able to populate not only extra-embryonic structures such as the amnion and the yolk sac, but also various embryonic tissues derived from the ectoderm and less frequently the mesoderm. Ectodermal chimerism was confined mainly to the head region and was observed in tissues derived from the neural ectoderm and the surface ectoderm, including the optic cup, diencephalon and lens. Although the possibility of random incorporation of transplanted cells into these embryonic structures cannot be excluded, these results would suggest that area opaca, a peripheral ring of cells in the avian embryo destined to form the extra-embryonic ectoderm and endoderm of the yolk sac, might harbor cells that have the potential to give rise to various cell types in the recipient chick embryo, including those derived from the surface ectoderm and neural ectoderm.

  20. Four new subdwarf B pulsators

    Science.gov (United States)

    Østensen, R.; Heber, U.; Silvotti, R.; Solheim, J.-E.; Dreizler, S.; Edelmann, H.

    2001-11-01

    We report the detection of short period oscillations in the sdB stars HS 0039+4302, HS 0444+0408, HS 1824+5745 and HS 2151+0857 from time-series photometry made at the Nordic Optical Telescope (NOT) of a sample of 55 candidates. Hence these four hot subdwarfs are new members of the EC 14026 class of pulsating sdB stars. HS 0039+4302 is a multi-mode pulsator with at least four distinct periods in the range between 182 and 234 s, and amplitudes up to 8 mma. HS 0444+0408 shows one dominant pulsation at 137 s (A ~ 12 mma) and a second weaker pulsation at 170 s (A ~ 3 mma). For HS 1824+5745 we find a single period of 139 s with an amplitude of about 5 mma. HS 2151+0857 shows four periods in the range 129-151 s with amplitudes between 2 and 5 mma. Our NLTE model atmosphere analysis of the time-averaged optical spectra place all stars well within the theoretical sdBV instability strip. Based on observations obtained at the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. }\\fnmsep\\thanks{ Based on observations collected at the German-Spanish Astronomical Center, Calar Alto, operated by the Max-Plank-Institute für Astronomie Heidelberg jointly with the Spanish National Commission for Astronomy. Based on observations collected at the European Southern Observatory, Chile (ESO No. 66.D-0031).

  1. Why do hot subdwarf stars pulsate?

    CERN Document Server

    Geier, S

    2015-01-01

    Hot subdwarf B stars (sdBs) are the stripped cores of red giants located at the bluest extension of the horizontal branch. Several different kinds of pulsators are found among those stars. The mechanism that drives those pulsations is well known and the theoretically predicted instability regions for both the short-period p-mode and the long-period g-mode pulsators match the observed distributions fairly well. However, it remains unclear why only a fraction of the sdB stars pulsate, while stars with otherwise very similar parameters do not show pulsations. From an observers perspective I review possible candidates for the missing parameter that makes sdB stars pulsate or not.

  2. Head pulsations in a centrifugal pump

    Science.gov (United States)

    Boiko, V. S.; Sotnyk, M. I.; Moskalenko, V. V.

    2017-08-01

    This article investigated the factors, which affect to the character of the head pulsations of a centrifugal pump. We investigated the dependence of the shape and depth of these pulsations from the operation mode of the pump. Was determined, that the head pulsations at the outlet of the impeller (pulsations on the blade passing frequency) cause head pulsations at the outlet of the pump, that have the same frequency, but differ in shape and depth. These pulsations depend on the design features of the flow-through part of the pump (from the ratio of hydraulic losses on the friction and losses on the vortex formation). A feature of the researches that were conducted is also the using of not only hydraulic but also electric modeling methods. It allows determining the values of the components of hydraulic losses.

  3. Introduction of DT40 cells into chick embryos

    Institute of Scientific and Technical Information of China (English)

    Mariko Toba; Fumio Ebara; Hiroki Furuta; Yuichi Matsushimal; Yasuo Kitagawa; Noboru Fujihara

    2001-01-01

    To examine the transfection of exogenous genes into chick embryos, applying the characteristics of avian leukosis virus (ALV)-induced chicken B cell line DT40 to the production of chimeric birds. Methods: The DT40cells incorporated with exogenous gene (lacZ constructs encoding Escherichia coli β-galactosidase: β-gal) were introduced into chick embryos by the injection of cells into stage X blastoderm. Manipulated eggs were incubated for 3 (trial 1 ) or 6 (trial 2) days, and the expression of lacZ DNA was detected by a histochemical staining method of β-galactosidase and polymerase chain reaction (PCR) analysis. Results: The survival rates of the manipulated embryos incubated for 3 days (stage 18-20: trial 1) and 6 days (stage 28, 30: trial 2) were about 42% and 38%, respectively.The expression rates of the lacZ gene in the embryos in the trials 1 and 2 were about 60% and 23%, respectively, for the survived embryos. Conclusio: The rate of embryonic viability and expression rate of introduced genes were not so high, but it suggested the possibility of utilizing the DT40 cells as a vector for carrying exogenous genes into chick embryos.

  4. First Kepler results on compact pulsators - I. Survey target selection and the first pulsators

    Science.gov (United States)

    Østensen, R. H.; Silvotti, R.; Charpinet, S.; Oreiro, R.; Handler, G.; Green, E. M.; Bloemen, S.; Heber, U.; Gänsicke, B. T.; Marsh, T. R.; Kurtz, D. W.; Telting, J. H.; Reed, M. D.; Kawaler, S. D.; Aerts, C.; Rodríguez-López, C.; Vučković, M.; Ottosen, T. A.; Liimets, T.; Quint, A. C.; Van Grootel, V.; Randall, S. K.; Gilliland, R. L.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Borucki, W. J.; Koch, D.; Quintana, E. V.

    2010-12-01

    We present results from the first two quarters of a survey to search for pulsations in compact stellar objects with the Kepler spacecraft. The survey sample and the various methods applied in its compilation are described, and spectroscopic observations are presented to separate the objects into accurate classes. From the Kepler photometry we clearly identify nine compact pulsators and a number of interesting binary stars. Of the pulsators, one shows the strong, rapid pulsations typical of a V361 Hya-type sdB variable (sdBV); seven show long-period pulsation characteristics of V1093 Her-type sdBVs; and one shows low-amplitude pulsations with both short and long periods. We derive effective temperatures and surface gravities for all the subdwarf B stars in the sample and demonstrate that below the boundary region where hybrid sdB pulsators are found, all our targets are pulsating. For the stars hotter than this boundary temperature a low fraction of strong pulsators (region, and several of the V1093 Her pulsators show low-amplitude modes in the short-period region, indicating that hybrid behaviour may be common in these stars, also outside the boundary temperature region where hybrid pulsators have hitherto been found.

  5. Enhancements of Impinging Flame by Pulsation

    Institute of Scientific and Technical Information of China (English)

    AySu; Ying-ChiehLiu

    2000-01-01

    Experimental investigations on the pulsating jet-impinging diffusion flame were executed.A soleoid valve was aligned upstream of the jet orifice and the methane fuel was controlled in open-closed cycles from 0 Hz to 20Hz.Results show that the open-closed cycles,indeed increase the fluctuations of the methane fuel obviously.The evolutions of pulsating flame therefore develop faster than the continuous impinging flame.The optimized pulating frequencies are near 9 to 11 hz from the Re=170 to 283.The temperature differences between that under optimized pulsating rate and full open condition(no pulsation)are ranging from 100 to 150 degree.The pulsating effect is more singnificant at low Reynolds number.The cross section of continuous impinging flame behaves as elliptic shape with axial ratio equals to 2/3.The tip of the impinging flame obviously crosses at 42mm above the impinging point.ecause of the phenomenon of pulsation flame,the flame sheet or flame front may not be identified clearly in the averaged temperature contours.Results shows that the averaged end-contour of pulsation flame rears at 38mm above the impinging point.By observation and experiment,the pulsating flame behaves more stable and efficient than the continuous impinging flame.

  6. Self-pulsation in Raman fiber amplifiers

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard; Ott, Johan Raunkjær; Rottwitt, Karsten

    2009-01-01

    Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated.......Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated....

  7. The contributions of BMP4, positive guidance cues, and repulsive molecules to cutaneous nerve formation in the chick hindlimb

    National Research Council Canada - National Science Library

    Honig, Marcia G; Camilli, Suzanne J; Surineni, Kiran M; Knight, Brian K; Hardin, Holly M

    2005-01-01

    Our previous surgical manipulations have shown that the target ectoderm is necessary for the initial formation of one of the major cutaneous nerves in the embryonic chick limb (Honig, M.G., Camilli, S.J., Xue, Q.S., 2004...

  8. Nonradial Pulsations in ɛ Persei

    Science.gov (United States)

    Saio, Hideyuki; Kambe, Eiji; Lee, Umin

    2000-11-01

    We consider the question of whether all the modes detected in the line profile variations of ɛ Persei are consistent with nonradial pulsations excited by the kappa mechanism at the opacity Z-bump. We have computed massive (12.5-14 Msolar) main-sequence models, adjusting the parameters such that the evolutionary tracks pass around the approximate position of ɛ Per on the H-R diagram. A linear nonadiabatic, nonradial pulsation analysis is applied to these models. The periods in the frame corotating with the stellar surface for the observed 2.3-4.5 hr modes are found to be consistent with the Z-bump kappa mechanism. We have found, however, that the longest-period mode (8.48 hr in the observer's frame) cannot be explained by the kappa mechanism. We have examined the effect of rotation on the stability of oscillations and found that the stabilizing effect is weak, so that only a few of the shortest-period modes are stabilized for the rotation speed of ɛ Per. No significant difference is found between prograde and retrograde modes in the stability. It is a puzzle why no retrograde mode has been detected in ɛ Per, which should equally be excited by the kappa mechanism. We also discuss the observed and theoretical line profile variations of ɛ Per in the Appendix.

  9. Blood Pulsation Intensity Video Mapping

    CERN Document Server

    Borges, Pedro Henrique de M

    2016-01-01

    In this study, we make non-invasive, remote, passive measurements of the heart beat frequency and determine the map of blood pulsation intensity in a region of interest (ROI) of skin. The ROI used was the forearm of a volunteer. The method employs a regular video camera and visible light, and the video acquisition takes less than 1 minute. The mean cardiac frequency found in our volunteer was within 1 bpm of the ground-truth value simultaneously obtained via earlobe plethysmography. Using the signals extracted from the video images, we have determined an intensity map for the blood pulsation at the surface of the skin. In this paper we present the experimental and data processing details of the work and well as limitations of the technique. ----------------------------------------- Neste estudo medimos a frequ\\^encia card\\'iaca de forma n\\~ao invasiva, remota e passiva e determinamos o mapa da atividade de pulsa\\c{c}\\~ao sangu\\'inea numa regi\\~ao de interesse (ROI) da pele. A ROI utilizada foi o antebra\\c{c}o...

  10. Pulsating star research from Antarctica

    Science.gov (United States)

    Chadid, Merieme

    2017-09-01

    This invited talk discusses the pulsating star research from the heart of Antarctica and the scientific polar challenges in the extreme environment of Antarctica, and how the new polar technology could cope with unresolved stellar pulsation enigmas and evolutionary properties challenges towards an understanding of the mysteries of the Universe. PAIX, the first robotic photometer Antarctica program, has been successfully launched during the polar night 2007. This ongoing program gives a new insight to cope with unresolved stellar enigmas and stellar oscillation challenges with a great opportunity to benefit from an access to the best astronomical site on Earth, Dome C. PAIX achieves astrophysical measurement time-series of stellar fields, challenging photometry from space. A continuous and an uninterrupted series of multi-color photometric observations has been collected each polar night - 150 days - without regular interruption, Earth's rotation effect. PAIX shows the first light curve from Antarctica and first step for the astronomy in Antarctica giving new insights in remote polar observing runs and robotic instruments towards a new technology.

  11. Occurrence and average behavior of pulsating aurora

    Science.gov (United States)

    Partamies, N.; Whiter, D.; Kadokura, A.; Kauristie, K.; Nesse Tyssøy, H.; Massetti, S.; Stauning, P.; Raita, T.

    2017-05-01

    Motivated by recent event studies and modeling efforts on pulsating aurora, which conclude that the precipitation energy during these events is high enough to cause significant chemical changes in the mesosphere, this study looks for the bulk behavior of auroral pulsations. Based on about 400 pulsating aurora events, we outline the typical duration, geomagnetic conditions, and change in the peak emission height for the events. We show that the auroral peak emission height for both green and blue emission decreases by about 8 km at the start of the pulsating aurora interval. This brings the hardest 10% of the electrons down to about 90 km altitude. The median duration of pulsating aurora is about 1.4 h. This value is a conservative estimate since in many cases the end of event is limited by the end of auroral imaging for the night or the aurora drifting out of the camera field of view. The longest durations of auroral pulsations are observed during events which start within the substorm recovery phases. As a result, the geomagnetic indices are not able to describe pulsating aurora. Simultaneous Antarctic auroral images were found for 10 pulsating aurora events. In eight cases auroral pulsations were seen in the southern hemispheric data as well, suggesting an equatorial precipitation source and a frequent interhemispheric occurrence. The long lifetimes of pulsating aurora, their interhemispheric occurrence, and the relatively high-precipitation energies make this type of aurora an effective energy deposition process which is easy to identify from the ground-based image data.

  12. Identification and localization of a novel zinc finger gene in developing chick skin and feather buds.

    Science.gov (United States)

    Padanilam, B J; Solursh, M

    1996-03-07

    We have cloned and sequenced a cDNA encoding a novel zinc finger protein (Fzf-1) containing two tandem repeats of zinc finger motifs of the C2H2 type. The cDNA is 3.0 Kb long and has an open reading frame which codes for a protein of 789 amino acids. The expression pattern of the zinc finger gene was studied in chick embryonic skin and feathers by in situ hybridization. The expression of the gene is found to be temporally and spatially regulated. In stage 38 chick embryos, the transcripts are localized to the epidermis but in 10-day-old embryos, the signal is localized to the forming dermis. In 12-day-old chick, the transcripts are localized to the mesenchymal region of the elongated feather buds. Reverse transcription followed by Polymerase Chain Reaction (RT-PCR) did not detect the transcripts in any other tissues.

  13. A Planet Found by Pulsations

    Science.gov (United States)

    Kohler, Susanna

    2016-10-01

    Searching for planets around very hot stars is much more challenging than looking around cool stars. For this reason, the recent discovery of a planet around a main-sequence A star is an important find both because of its unique position near the stars habitable zone, and because of the way in which the planet was discovered.Challenges in VariabilityIn the past three decades, weve discovered thousands of exoplanets yet most of them have been found around cool stars (like M dwarfs) or moderate stars (like G stars like our Sun). Very few of the planets that weve found orbit hot stars; in fact, weve only discovered ~20 planets orbiting the very hot, main-sequence A stars.The instability strip, indicated on an H-R diagram. Stellar classification types are listed across the bottom of the diagram. Many main-sequence A stars reside in the instability strip. [Rursus]Why is this? We dont expect that main-sequence A stars host fewer planets than cooler stars. Instead, its primarily because the two main techniques that we use to find planets namely, transits and radial velocity cant be used as effectively on the main-sequence A stars that are most likely to host planets, because the luminosities of these stars are often variable.These stars can lie on whats known as the classical instability strip in the Herzsprung-Russell diagram. Such variable stars pulsate due to changes in the ionization state of atoms deep in their interiors, which causes the stars to puff up and then collapse back inward. For variable main-sequence A stars, the periods for these pulsations can be several to several tens of times per day.These very pulsations that make transits and radial-velocity measurements so difficult, however, can potentially be used to detect planets in a different way. Led by Simon Murphy (University of Sydney, Australia and Aarhus University, Denmark), a team of scientists has recently detected the first planet ever to be discovered around a main-sequence A star from the timing

  14. Exposure to Excess Phenobarbital Negatively Influences the Osteogenesis of Chick Embryos

    OpenAIRE

    Yu Yan; Xin Cheng; Ren-hao Yang; He Li; Jian-long Chen; Zheng-lai Ma; Guang Wang; Manli Chuai; Xuesong Yang

    2016-01-01

    Phenobarbital is an antiepileptic drug that is widely used to treat epilepsy in a clinical setting. However, a long term of phenobarbital administration in pregnant women may produce side effects on embryonic skeletogenesis. In this study, we aim to investigate the mechanism by which phenobarbital treatment induces developmental defects in long bones. We first determined that phenobarbital treatment decreased chondrogenesis and inhibited the proliferation of chondrocytes in chick embryos. Phe...

  15. Piezoelectric actuator for pulsating jets

    Science.gov (United States)

    Brissaud, Michel; Gonnard, Paul; Bera, Jean-Christophe; Sunyach, Michel

    2000-08-01

    Recent researches in aeronautics showed that fluidic actuator systems could offer possibilities for drag reduction and lift improvement. To this end many actuator types were designed. This paper deals with the design, fabrication and test of piezoelectric actuator in order to generate pulsated jets normal to a surface and control air flow separation. It is based on the flexural displacement of a rectangular metal plate clamped on one of its large edge. Piezoelectric patches cemented on the plate were used for driving into vibration the actuator. Experimental measurements show that pulsed flow velocities are adjustable from 1.5m/s to 35m/s through a 100x1mm2 slit andwithin a 100 to 400 Hz frequency range. Prototype provides the jet performances classically required for active control flow.

  16. Pulsations in close binaries: challenges and opportunities

    Directory of Open Access Journals (Sweden)

    Maceroni C.

    2015-01-01

    Full Text Available CoRoT and Kepler provided a precious by-product: a number of eclipsing binaries containing variable stars and, among these, non-radial pulsators. This providential occurrence allows combining independent information from two different phenomena whose synergy yields scientific results well beyond those from the single sources. In particular, the analysis of pulsations in eclipsing binary components throws light on the internal structure of the pulsating star, on the system evolution, and on the role of tidal forces in exciting the oscillations. The case study of the Kepler target KIC 3858884 is illustrative of the difficulties of analysis and of the achievements in this rapidly developing field.

  17. Pulsative hematoma: A penile fracture complication

    Directory of Open Access Journals (Sweden)

    Nale Đorđe

    2007-01-01

    Full Text Available Background. Fracture of the penis is a direct blunt trauma of the erect or semi-erect penis. It can be treated by conservative or surgical means. Retrospective analyses of conservative penile fracture treatment reveal frequent immediate and later complications. Case report. We presented a 41- year-old patient with pulsative hematoma caused by an unusual fracture of the penis. Fracture had appeared 40 days before the admittance during a sexual intercourse. The patient was treated surgically. Conclusion. Pulsative hematoma (pulsative diverticulum is a very rare, early complication of a conservatively treated penile fracture. Surgical treatment has an advantage over surgical one, which was confirmed by our case report.

  18. Self-pulsation in Raman fiber amplifiers

    OpenAIRE

    Pedersen, Martin Erland Vestergaard; Ott, Johan Raunkjær; Rottwitt, Karsten

    2009-01-01

    Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated.

  19. Stellar pulsation and rotation in NGC 6811

    Science.gov (United States)

    Rodríguez, E.; Ocando, S.; López-González, M. J.; Martín-Ruiz, S.

    2017-03-01

    We present the results of the frequency analysis for a selected sample of pulsating δ Sct- and γ Dor-type stars in the field of the open cluster NGC 6811, which have been observed in short-cadence (SC) mode by the Kepler satellite. In all cases, the resulting frequency spectra are very complex, especially when the dominant pulsation is that of the δ Sct type, that is, short-period pulsations corresponding to excited pressure (p) modes. In all cases, the δ Sct stars are shown to be essentially δ Sct/ γ Dor hybrid pulsators. However, the opposite seems not to be true. We also find that the δ Sct-type peaks commonly are not stable in amplitude. Many of the main peaks significantly change their amplitudes over relatively short time scales. For a large percentage of pulsators in our sample we also find that the variability shown in the light curves is not produced by a single cause, but a combination of various sources: δ Sct- and γ Dor-type pulsations together with rotational modulation produced by starspots in the surfaces of these stars. This is an indication of stellar activity in the surfaces of these relatively hot stars of spectral type A(-F). Sometimes, activity dominates the luminosity variations in various pulsating stars in our sample. Eclipsing binarity is also detected in a few cases. Flares are also detected in one of the δ Sct-type pulsators. This is an indication of unusual strong activity for this kind of hot stars.

  20. Statistical study of dayside pulsating aurora

    Science.gov (United States)

    Kanmae, T.; Kadokura, A.; Ogawa, Y.; Ebihara, Y.; Motoba, T.; Gerrard, A. J.; Weatherwax, A. T.

    2015-12-01

    Pulsating aurora normally occurs after a substorm breakup in the midnight sector, often observed to persist through the morning sector and beyond. Indeed, it has also been observed on the dayside; however, the characteristics of the dayside pulsating aurora are poorly known. A handful of observational studies have been reported, but the results are somewhat disputable because most of the studies had non-uniform sampling of the dark dayside region. Furthermore, the previous studies used photometer data, with which the spatial characteristics of the pulsating aurora cannot be examined. To determine both temporal and spatial characteristics of the pulsating aurora, we have studied three years of all-sky image data obtained at the South Pole station. Because of its unique geographical location, the station has 24 hours of darkness during the austral winter from April to August, providing an ideal platform for studying dayside aurora. In a preliminary survey of the data, we have identified the pulsating auroras in 198 days out of 365 days of observations. The magnetic local time (MLT) distribution of the occurrence peaks between 9:00 and 11:00, but shows no or little dependence on the geomagnetic activity. In many events, pulsating patches initially appear as east-west aligned arc segments and later in the afternoon sector develop into large, diffuse patches, which occasionally fill a large part of the field of view. Using the long-term data, we will statistically examine both temporal (occurrence rate, duration and pulsation period) and spatial (sizes and shapes) characteristics of the dayside pulsating aurora.

  1. A motion picture presentation of magnetic pulsations

    Science.gov (United States)

    Suzuki, A.; Kim, J. S.; Sugura, M.; Nagano, H.

    1981-01-01

    Using the data obtained from the IMS North American magnetometer network stations at high latitudes, a motion picture was made by a computer technique, describing time changes of Pc5 and Pi3 magnetic pulsation vectors. Examples of pulsation characteristics derived from this presentation are regional polarization changes including shifts of polarization demarcation lines, changes in the extent of an active region and its movement with time.

  2. A new gestational diabetes mellitus model: hyperglycemia-induced eye malformation via inhibition of Pax6 in the chick embryo

    Directory of Open Access Journals (Sweden)

    Shi-Jie Zhang

    2016-02-01

    Full Text Available Gestational diabetes mellitus (GDM is one of the leading causes of fetal malformations. However, few models have been developed to study the underlying mechanisms of GDM-induced fetal eye malformation. In this study, a high concentration of glucose (0.2 mmol per egg was injected into the air sac of chick embryos on embryo development day (EDD 1 to develop a hyperglycemia model. Results showed that 47.3% of embryonic eye malformation happened on EDD 5. In this model, the key genes regulating eye development, Pax6, Six3 and Otx2, were downregulated by hyperglycemia. Among these genes, the expression of Pax6 was the most vulnerable to hyperglycemia, being suppressed by 70%. A reduction in Pax6 gene expression induced eye malformation in chick embryos. However, increased expression of Pax6 in chick embryos could rescue hyperglycemia-induced eye malformation. Hyperglycemia stimulated O-linked N-acetylglucosaminylation, which caused oxidative stress in chick embryos. Pax6 was found to be vulnerable to free radicals, but the antioxidant edaravone could restore Pax6 expression and reverse eye malformation. These results illustrated a successful establishment of a new chick embryo model to study the molecular mechanism of hyperglycemia-induced eye malformation. The suppression of the Pax6 gene is probably mediated by oxidative stress and could be a crucial target for the therapy of GDM-induced embryonic eye malformation.

  3. Experimental toxoplasmosis in broiler chicks.

    Science.gov (United States)

    Kaneto, C N; Costa, A J; Paulillo, A C; Moraes, F R; Murakami, T O; Meireles, M V

    1997-05-01

    To evaluate chicken toxoplasmosis both as an economic and a public health subject, 84 broiler chicks of a commercial strain, 30 days old, were distributed into seven groups of 12 birds (three replications of four chicks) experimentally infected with three developing T. gondii stages of the P strain as follows: tachyzoites, intravenous (two groups: 5.0 x 10(5) and 5.0 x 10(6)), cysts, per os (two groups: 1.0 x 10(2) and 1.0 x 10(3)) and oocysts, per os (three groups: 5.0 x 10(2), 5.0 x 10(3) and 5.0 x 10(4)). Twelve chicks received only a placebo (control group). During the next 30 days the following parameters were estimated: productivity (weight gain and feed conversion), clinical signs, including rectal temperature and parasitemia (bioassay). No clinical signs suggesting toxoplasmosis were seen and no statistical differences on productivity standards were found in comparison between inoculated and control chicks. However, fowls inoculated with tachyzoites and oocysts occasionally showed hyperthermia. Some haematological changes were detected in fowls inoculated with T. gondii. Anatomo-histopathological changes were not observed. From 14 parasitemias detected, 35.7% appeared on the 5th day after inoculation and 57.1% of them resulted from oocysts inoculation. After 30-35 days all birds were slaughtered: fragments from 12 organs or tissues from each of them were subjected to artificial peptic digestion and after that injected into T. gondii antibody-free mice (IIFR). T. gondii was detected in brain (12), pancreas (five), spleen (five), retina (five), kidney (two), heart (four), proventriculus (three), liver (two), intestine (two), lung (one), and skeletal muscle (one). Similar to observations with parasitemia, from 42 T. gondii isolations, 59.5% came from chicks which had received oocysts. It can thus be inferred that the developing form, expelled by cats, is the most important for T. gondii chicken infection and that brain is the most infected organ in birds

  4. Maturation of firing pattern in chick vestibular nucleus neurons.

    Science.gov (United States)

    Shao, M; Hirsch, J C; Peusner, K D

    2006-08-25

    The principal cells of the chick tangential nucleus are vestibular nucleus neurons participating in the vestibuloocular and vestibulocollic reflexes. In birds and mammals, spontaneous and stimulus-evoked firing of action potentials is essential for vestibular nucleus neurons to generate mature vestibular reflex activity. The emergence of spike-firing pattern and the underlying ion channels were studied in morphologically-identified principal cells using whole-cell patch-clamp recordings from brain slices of late-term embryos (embryonic day 16) and hatchling chickens (hatching day 1 and hatching day 5). Spontaneous spike activity emerged around the perinatal period, since at embryonic day 16 none of the principal cells generated spontaneous action potentials. However, at hatching day 1, 50% of the cells fired spontaneously (range, 3 to 32 spikes/s), which depended on synaptic transmission in most cells. By hatching day 5, 80% of the principal cells could fire action potentials spontaneously (range, 5 to 80 spikes/s), and this activity was independent of synaptic transmission and showed faster kinetics than at hatching day 1. Repetitive firing in response to depolarizing pulses appeared in the principal cells starting around embryonic day 16, when calcium-dependent potassium current modulated both the spontaneous and evoked spike firing activity. Altogether, these in vitro studies showed that during the perinatal period, the principal cells switched from displaying no spontaneous spike activity at resting membrane potential and generating one spike on depolarization to the tonic firing of spontaneous and evoked action potentials.

  5. Objective detection of retinal vessel pulsation.

    Directory of Open Access Journals (Sweden)

    William H Morgan

    Full Text Available PURPOSE: Retinal venous pulsation detection is a subjective sign, which varies in elevated intracranial pressure, venous obstruction and glaucoma. To date no method can objectively measure and identify pulsating regions. METHOD: Using high resolution video-recordings of the optic disk and retina we measured fluctuating light absorption by haemoglobin during pulsation. Pulsation amplitude was calculated from all regions of the retinal image video-frames in a raster pattern. Segmented retinal images were formed by objectively selecting regions with amplitudes above a range of threshold values. These were compared to two observers manually drawing an outline of the pulsating areas while viewing video-clips in order to generate receiver operator characteristics. RESULTS: 216,515 image segments were analysed from 26 eyes in 18 research participants. Using data from each eye, the median area under the receiver operator curve (AU-ROC was 0.95. With all data analysed together the AU-ROC was 0.89. We defined the ideal threshold amplitude for detection of any pulsating segment being that with maximal sensitivity and specificity. This was 5 units (95% confidence interval 4.3 to 6.0 compared to 12 units before any regions were missed. A multivariate model demonstrated that ideal threshold amplitude increased with increased variation in video-sequence illumination (p = 0.0119, but between the two observers (p = 0.0919 or other variables. CONCLUSION: This technique demonstrates accurate identification of retinal vessel pulsating regions with no areas identified manually being missed with the objective technique. The amplitude values are derived objectively and may be a significant advance upon subjective ophthalmodynamometric threshold techniques.

  6. Evolution of the mammalian embryonic pluripotency gene regulatory network

    Science.gov (United States)

    Fernandez-Tresguerres, Beatriz; Cañon, Susana; Rayon, Teresa; Pernaute, Barbara; Crespo, Miguel; Torroja, Carlos; Manzanares, Miguel

    2010-01-01

    Embryonic pluripotency in the mouse is established and maintained by a gene-regulatory network under the control of a core set of transcription factors that include octamer-binding protein 4 (Oct4; official name POU domain, class 5, transcription factor 1, Pou5f1), sex-determining region Y (SRY)-box containing gene 2 (Sox2), and homeobox protein Nanog. Although this network is largely conserved in eutherian mammals, very little information is available regarding its evolutionary conservation in other vertebrates. We have compared the embryonic pluripotency networks in mouse and chick by means of expression analysis in the pregastrulation chicken embryo, genomic comparisons, and functional assays of pluripotency-related regulatory elements in ES cells and blastocysts. We find that multiple components of the network are either novel to mammals or have acquired novel expression domains in early developmental stages of the mouse. We also find that the downstream action of the mouse core pluripotency factors is mediated largely by genomic sequence elements nonconserved with chick. In the case of Sox2 and Fgf4, we find that elements driving expression in embryonic pluripotent cells have evolved by a small number of nucleotide changes that create novel binding sites for core factors. Our results show that the network in charge of embryonic pluripotency is an evolutionary novelty of mammals that is related to the comparatively extended period during which mammalian embryonic cells need to be maintained in an undetermined state before engaging in early differentiation events. PMID:21048080

  7. Expression of Fgf19 in the developing chick eye.

    Science.gov (United States)

    Francisco-Morcillo, Javier; Sánchez-Calderón, Hortensia; Kawakami, Yasuhiko; Izpisúa Belmonte, Juan Carlos; Hidalgo-Sánchez, Matías; Martín-Partido, Gervasio

    2005-04-21

    Fibroblast growth factor 19 (FGF19) is a new member of the FGF family of growth factors. Here, we describe the localization of Fgf19 mRNA in the developing chick retina and lens in stages from the Hamburger and Hamilton stage 15 (HH15) to postnatal day 30 (P30). Fgf19 was expressed in a transient manner in postmitotic neuroblasts during the migration from the ventricular surface to their final location. Moreover, from HH31 (embryonic day 7, E7) on, a subset of lined up Fgf19 expressing cells was distributed in the outer region of the presumptive INL. These cells were Pax6 immunoreactive horizontal cells. During the last third of embryogenesis, Fgf19 expression in the retina was progressively down-regulated and was not detected at P30. Also, it was transiently expressed in the equatorial region of the lens.

  8. White Dwarf Pulsational Constraints on Stellar Evolution

    Science.gov (United States)

    Dunlap, Bart H.; Clemens, J. Christopher; O'Brien, Patrick C.; Hermes, J. J.; Fuchs, Joshua T.

    2017-01-01

    The complex processes that convert a protostellar cloud into a carbon/oxygen-core white dwarf star are distilled and modeled in state of the art stellar evolution codes. Many of these processes are well-constrained, but several are uncertain or must be parameterized in the models because a complete treatment would be computationally prohibitive—turbulent motions such as convective overshoot cannot, for example, be modeled in 1D. Various free parameters in the models must therefore be calibrated. We will discuss how white dwarf pulsations can inform such calibrations. The results of all prior evolution are cemented into the interiors of white dwarf stars and, so, hidden from view. However, during certain phases of their cooling, pulsations translate the star's evolutionary history into observable surface phenomena. Because the periods of a pulsating white dwarf star depend on an internal structure assembled as it evolved to its final state, white dwarf pulsation periods can be viewed as observable endpoints of stellar evolution. For example, the thickness of the helium layer in a white dwarf directly affects its pulsations; the observed periods are, therefore, a function of the number of thermal pulses during which the star converts helium into core material on the asymptotic giant branch. Because they are also a function of several other significant evolutionary processes, several pulsation modes are necessary to tease all of these apart. Unfortunately, white dwarf pulsators typically do not display enough oscillation modes to constrain stellar evolution. To avoid this limitation, we consider the pulsations of the entire collection of hot pulsating hydrogen-atmosphere white dwarf stars (DAVs). Though any one star may not have sufficient information to place interesting constraints on its evolutionary history, taken together, the stars show a pattern of modes that allows us to test evolutionary models. For an example set of published evolutionary models, we show a

  9. Long Period Variables: questioning the pulsation paradigm

    CERN Document Server

    Berlioz-Arthaud, Paul

    2016-01-01

    Long period variables, among them Miras, are thought to be pulsating. Under this approach the whole star inflates and deflates along a period that can vary from 100 to 900 days; that pulsation is assumed to produce shock waves on the outer layers of the star that propagate into the atmosphere and could account for the increase in luminosity and the presence of emission lines in the spectra of these stars. However, this paradigm can seriously be questioned from a theoretical point of view. First, in order to maintain a radial pulsation, the spherical symmetry of the star must be preserved: how can it be reconciled with the large convective cells present in these stars? or when close companions are detected? Secondly, how different radial and non-radial pulsation modes of a sphere could be all damped except one radial mode? These problems have no solution and significantly weigh on the pulsation paradigm. Acknowledging this inconsistency, we show that a close companion around these stars could account for the s...

  10. Connections between whistlers and pulsation activity

    Directory of Open Access Journals (Sweden)

    J. Verö

    Full Text Available Simultaneous whistler records of one station and geomagnetic pulsation (Pc3 records at three stations were compared. In a previous study correlation was found between occurrence and L value of propagation/excitation for the two phenomena. The recently investigated simultaneous records have shown that the correlation is better on longer time scales (days than on shorter ones (minutes, but the L values of the propagation of whistlers/excitation of pulsations are correlated, i.e. if whistlers propagate in higher latitude ducts, pulsations have periods longer than in the case when whistlers propagate in lower latitude ducts.

    Key words: Electromagnetics (wave propagation - Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and instabilities

  11. Pulsating star research and the Gaia revolution

    Directory of Open Access Journals (Sweden)

    Eyer Laurent

    2017-01-01

    Full Text Available In this article we present an overview of the ESA Gaia mission and of the unprecedented impact that Gaia will have on the field of variable star research. We summarise the contents and impact of the first Gaia data release on the description of variability phenomena, with particular emphasis on pulsating star research. The Tycho-Gaia astrometric solution, although limited to 2.1 million stars, has been used in many studies related to pulsating stars. Furthermore a set of 3,194 Cepheids and RR Lyrae stars with their times series have been released. Finally we present the plans for the ongoing study of variable phenomena with Gaia and highlight some of the possible impacts of the second data release on variable, and specifically, pulsating stars.

  12. Pulsating star research and the Gaia revolution

    Science.gov (United States)

    Eyer, Laurent; Clementini, Gisella; Guy, Leanne P.; Rimoldini, Lorenzo; Glass, Florian; Audard, Marc; Holl, Berry; Charnas, Jonathan; Cuypers, Jan; Ridder, Joris De; Evans, Dafydd W.; de Fombelle, Gregory Jevardat; Lanzafame, Alessandro; Lecoeur-Taibi, Isabelle; Mowlavi, Nami; Nienartowicz, Krzysztof; Riello, Marco; Ripepi, Vincenzo; Sarro, Luis; Süveges, Maria

    2017-09-01

    In this article we present an overview of the ESA Gaia mission and of the unprecedented impact that Gaia will have on the field of variable star research. We summarise the contents and impact of the first Gaia data release on the description of variability phenomena, with particular emphasis on pulsating star research. The Tycho-Gaia astrometric solution, although limited to 2.1 million stars, has been used in many studies related to pulsating stars. Furthermore a set of 3,194 Cepheids and RR Lyrae stars with their times series have been released. Finally we present the plans for the ongoing study of variable phenomena with Gaia and highlight some of the possible impacts of the second data release on variable, and specifically, pulsating stars.

  13. Benefit of pulsation in soft corals.

    Science.gov (United States)

    Kremien, Maya; Shavit, Uri; Mass, Tali; Genin, Amatzia

    2013-05-28

    Soft corals of the family Xeniidae exhibit a unique, rhythmic pulsation of their tentacles (Movie S1), first noted by Lamarck nearly 200 y ago. However, the adaptive benefit of this perpetual, energetically costly motion is poorly understood. Using in situ underwater particle image velocimetry, we found that the pulsation motions thrust water upward and enhance mixing across the coral-water boundary layer. The induced upward motion effectively prevents refiltration of water by neighboring polyps, while the intensification of mixing, together with the upward flow, greatly enhances the coral's photosynthesis. A series of controlled laboratory experiments with the common xeniid coral Heteroxenia fuscescens showed that the net photosynthesis rate during pulsation was up to an order of magnitude higher than during the coral's resting, nonpulsating state. This enhancement diminished when the concentration of oxygen in the ambient water was artificially raised, indicating that the enhancement of photosynthesis was due to a greater efflux of oxygen from the coral tissues. By lowering the internal oxygen concentration, pulsation alleviates the problem of reduced affinity of ribulose-1,5-bisphosphate carboxylase oxygenase (RuBisCO) to CO2 under conditions of high oxygen concentrations. The photosynthesis-respiration ratio of the pulsating H. fuscescens was markedly higher than the ratios reported for nonpulsating soft and stony corals. Although pulsation is commonly used for locomotion and filtration in marine mobile animals, its occurrence in sessile (bottom-attached) species is limited to members of the ancient phylum Cnidaria, where it is used to accelerate water and enhance physiological processes.

  14. Pulsating White Dwarfs in Globular Clusters

    Science.gov (United States)

    Kanaan, A.; Zabot, A.; Fraga, L.

    2012-09-01

    We present our current efforts to detect pulsating white dwarfs in globular clusters and analyze the future of this area when the Extremely Large Telescope (ELT), the Giant Magellan Telescope (GMT) and the Thirty-Meter Telescope (TMT) all become operational. Today we are able to detect pulsating white dwarfs in M 4, NGC 6397 and NGC 6752. When ELT comes on line we should be able to improve the quality of data for the nearby clusters and push the limit to at least 3 magnitudes further, up to NGC 6626, increasing the number of observable clusters from 3 to 20.

  15. Chick metabolic rate and growth in three species of albatross: a comparative study.

    Science.gov (United States)

    Phillips, R A; Green, J A; Phalan, B; Croxall, J P; Butler, P J

    2003-05-01

    The relative importance of genetic vs. environmental factors in determining the pattern of avian post-embryonic development is much debated. Previous cross-fostering of albatrosses suggested that although inter-specific variation in growth rate was determined primarily by differences in dietary energy content, species-specific constraints might have evolved that could limit maximal growth, even in chicks fed at similar rates and on similar diets. This study aimed to determine whether intrinsic differences in resting metabolic rate were apparent during the linear phase of growth in chicks of three species (black-browed, grey-headed and light-mantled sooty albatrosses). There was a gradual increase in absolute, and a reduction in mass-specific metabolic rate from 5.0 W kg(-1) during the earliest part of linear growth, to 3.5 W kg(-1) by the time chicks reached peak mass. These values are considerably higher than in resting adults of comparable or lower mass, presumably reflecting the large size and high metabolic demand of organs involved in rapid nutrient processing and tissue synthesis by chicks. The lack of any detectable inter-specific variation in the pattern of metabolic rate changes casts some doubt on the existence of fundamental differences in growth rate that cannot be attributed simply to differences in dietary energy or nutrient delivery rate.

  16. Acutely altered hemodynamics following venous obstruction in the early chick embryo.

    Science.gov (United States)

    Stekelenburg-de Vos, Sandra; Ursem, Nicolette T C; Hop, Wim C J; Wladimiroff, Juriy W; Gittenberger-de Groot, Adriana C; Poelmann, Robert E

    2003-03-01

    In the venous clip model specific cardiac malformations are induced in the chick embryo by obstructing the right lateral vitelline vein with a microclip. Clipping alters venous return and intracardiac laminar blood flow patterns, with secondary effects on the mechanical load of the embryonic myocardium. We investigated the instantaneous effects of clipping the right lateral vitelline vein on hemodynamics in the stage-17 chick embryo. 32 chick embryos HH 17 were subdivided into venous clipped (N=16) and matched control embryos (N=16). Dorsal aortic blood flow velocity was measured with a 20 MHz pulsed Doppler meter. A time series of eight successive measurements per embryo was made starting just before clipping and ending 5h after clipping. Heart rate, peak systolic velocity, time-averaged velocity, peak blood flow, mean blood flow, peak acceleration and stroke volume were determined. All hemodynamic parameters decreased acutely after venous clipping and only three out of seven parameters (heart rate, time-averaged velocity and mean blood flow) showed a recovery to baseline values during the 5h study period. We conclude that the experimental alteration of venous return has major acute effects on hemodynamics in the chick embryo. These effects may be responsible for the observed cardiac malformations after clipping.

  17. CHICKS

    African Journals Online (AJOL)

    JOURNAL OF AGRICULTURE AND SOCIAL RESEARCH VOL. 4, No. ... increase in the use of feed additives as growth promoters in animal production (Manie .... It could also be due to increased absorptive capacity of the small ... PGD project.

  18. Growth patterns of Hawaiian Stilt chicks

    Science.gov (United States)

    Reed, J.M.; Gray, E.M.; Lewis, D.; Oring, L.W.; Coleman, R.; Burr, T.; Luscomb, P.

    1999-01-01

    We studied chick growth and plumage patterns in the endangered Hawaiian Stilt (Himantopus mexicanus knudseni). Body mass of captive chicks closely fit a Gompertz growth curve, revealing a growth coefficient (K) of 0.065 day-1 and point of inflection (T) of 17 days. When chicks fledged about 28 days after hatching, they weighed only 60% of adult body mass; at 42 d, birds still were only 75% of adult mass; culmen, tarsus, and wing chord at fledging also were less than adult size. This trend of continued growth to adult size after fledging is typical for most shorebirds. After hatching, captive chicks grew more rapidly than wild chicks, probably because of an unlimited food supply. We found no evidence for adverse effects of weather on the growth of wild chicks. As with other shorebirds, the tarsus started relatively long, with culmen and then wing chord growing more rapidly in later development. Tarsal and wing chord growth were sigmoidal, whereas culmen growth was linear. We describe plumage characteristics of weekly age classes of chicks to help researchers age birds in the wild.

  19. Effects of DDT and permethrin on neurite growth in cultured neurons of chick embryo brain and Lymnaea stagnalis.

    Science.gov (United States)

    Ferguson, C A; Audesirk, G

    1990-01-01

    The pesticides permethrin and 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT), dissolved in either ethanol (EtOH) or dimethylsulphoxide (DMSO), were studied to determine their effect on neurite growth from cultured neurons of Lymnaea stagnalis and embryonic chicks. Both of these toxins decreased the percentage of neurons growing neurites, mean neurite length, and number of neurites/cell in a dose-dependent manner. DMSO increased the toxicity of permethrin and DDT in L. stagnalis neurons. EtOH was not used as a solvent with the embryonic chick cultures. Pre-existing neurites of L. stagnalis neurons exposed to permethrin regressed in a dose- and time-dependent manner. These two toxins may affect neurite outgrowth through interference with intracellular calcium regulation.

  20. Evaluation of pump pulsation in respirable size-selective sampling: part I. Pulsation measurements.

    Science.gov (United States)

    Lee, Eun Gyung; Lee, Larry; Möhlmann, Carsten; Flemmer, Michael M; Kashon, Michael; Harper, Martin

    2014-01-01

    Pulsations generated by personal sampling pumps modulate the airflow through the sampling trains, thereby varying sampling efficiencies, and possibly invalidating collection or monitoring. The purpose of this study was to characterize pulsations generated by personal sampling pumps relative to a nominal flow rate at the inlet of different respirable cyclones. Experiments were conducted using a factorial combination of 13 widely used sampling pumps (11 medium and 2 high volumetric flow rate pumps having a diaphragm mechanism) and 7 cyclones [10-mm nylon also known as Dorr-Oliver (DO), Higgins-Dewell (HD), GS-1, GS-3, Aluminum, GK2.69, and FSP-10]. A hot-wire anemometer probe cemented to the inlet of each cyclone type was used to obtain pulsation readings. The three medium flow rate pump models showing the highest, a midrange, and the lowest pulsations and two high flow rate pump models for each cyclone type were tested with dust-loaded filters (0.05, 0.21, and 1.25mg) to determine the effects of filter loading on pulsations. The effects of different tubing materials and lengths on pulsations were also investigated. The fundamental frequency range was 22-110 Hz and the magnitude of pulsation as a proportion of the mean flow rate ranged from 4.4 to 73.1%. Most pump/cyclone combinations generated pulse magnitudes ≥10% (48 out of 59 combinations), while pulse shapes varied considerably. Pulsation magnitudes were not considerably different for the clean and dust-loaded filters for the DO, HD, and Aluminum cyclones, but no consistent pattern was observed for the other cyclone types. Tubing material had less effect on pulsations than tubing length; when the tubing length was 183cm, pronounced damping was observed for a pump with high pulsation (>60%) for all tested tubing materials except for the Tygon Inert tubing. The findings in this study prompted a further study to determine the possibility of shifts in cyclone sampling efficiency due to sampling pump pulsations

  1. X-ray Pulsation Searches with NICER

    Science.gov (United States)

    Ray, Paul S.; Arzoumanian, Zaven

    2016-04-01

    The Neutron Star Interior Composition Explorer (NICER) is an X-ray telescope with capabilities optimized for the study of the structure, dynamics, and energetics of neutron stars through high-precision timing of rotation- and accretion-powered pulsars in the 0.2-12 keV band. It has large collecting area (twice that of the XMM-Newton EPIC-pn camera), CCD-quality spectral resolution, and high-precision photon time tagging referenced to UTC through an onboard GPS receiver. NICER will begin its 18-month prime mission as an attached payload on the International Space Station around the end of 2016. I will describe the science planning for the pulsation search science working group, which is charged with searching for pulsations and studying flux modulation properties of pulsars and other neutron stars. A primary goal of our observations is to detect pulsations from new millisecond pulsars that will contribute to NICER’s studies of the neutron star equation of state through pulse profile modeling. Beyond that, our working group will search for pulsations in a range of source categories, including LMXBs, new X-ray transients that might be accreting millisecond pulsars, X-ray counterparts to unassociated Fermi LAT sources, gamma-ray binaries, isolated neutron stars, and ultra-luminous X-ray sources. I will survey our science plans and give an overview of our planned observations during NICER’s prime mission.

  2. A Pulsation Mechanism for GW Virginis Variables

    Science.gov (United States)

    Cox, Arthur N.

    2003-03-01

    The mechanism that produces pulsations in the hottest pre-white dwarfs has been uncertain since the early work indicated that helium is a poison that smooths opacity bumps in the opacity-temperature plane caused by the ionizations of the large observed amounts of carbon and oxygen. Very little helium seemed to be needed to prevent the kappa effect pulsation driving, but helium amounts of almost half of the mass in the surface composition are observed in the pulsating PG 1159-035 stars called the GW Virginis variables. Rather little change in the C and O surface abundances is observed from the hottest (RX J2117.1+3412 at 170,000 K) to the coolest (PG 0122+200 at 80,000 K) GW Vir variables. Actually the shortest observed periods (300-400 s) of these variables are generally predicted to be unstable in all models, but the longest observed periods (up to 1000 s) are difficult to excite. Three recent investigations differ in their conclusions, with two finding that helium and even a slight amount of hydrogen does not prevent the kappa effect of C and O ionizations. A more detailed study reported here confirms the poisoning effect of helium. However, the ionization K- and L-edge opacity of the original iron, whose global abundance is unaffected by all previous evolution, especially if enhanced by radiation absorption levitation, can give different, previously unexplored, opacity driving that can explain the observed pulsations. But even this iron ionization driving can be somewhat poisoned by bump smoothing if the C and O abundances are large. Nonvariable GW Vir stars in the observed instability strip could be the result of small composition variations in the pulsation driving layers.

  3. The Teratogenic Effects of Antiepileptic Drug, Topiramate, on the Development of Chick Embryos

    Directory of Open Access Journals (Sweden)

    Jantima Roongruangchai

    2017-05-01

    Full Text Available Background: Anti-epileptic drugs are known to be the risk of teratogenicity. Topiramate (TPM is a new kind of such drug, for which no research has confirmed the incidence of producing congenital abnormalities. Objective: This study was conducted to study the teratogenic effects of TPM by using chick embryos as an animal model and the results can be compared to the human embryo of the same stage. Methods: Fertilized Leghorn hen eggs were injected in ovo with two concentrations of TPM, which were 10mg, and 20mg, in NSS at a volume of 0.1 ml into the yolk sac at 21 hrs of incubation and repeated injections at 72 hrs at a volume of 0.05 ml. The chick embryos on day 3, 6 and 11 of incubation were sacrificed and all living embryos were processed for total mount and serial section. Results: The mortality rate increased corresponding to the concentrations of TPM, and the embryonic stage. The total mount of day 3 showed major abnormalities of the eye and heart, such as microphthalmia and looser of heart looping. The serial section of day 3 showed opening of the anterior neuropore, ectopia viscerae and multiple malformations of the eye and heart. Day 6 chick embryos showed ectopia cordis and ectopia viscerae. Moreover, there were retardation and abnormalities of several organs such as eye, heart, liver, mesonephros and gonads. Day 11 chick embryos showed ectopia viscerae and several growth retardations, retardation of ossification of both limb bones and skull bones. Conclusion: This study showed that TPM might cause embryonic death, growth retardation and abnormalities of the eye, heart, an opening of the anterior neuropore and ectopia viscerae. This might indicate abnormalities to the baby born from mother with gestational epilepsy who was taking this drug continuously, and it might lead to spontaneous abortion or congenital anomalies of the fetus.

  4. Transplantation of mammalian embryonic stem cells and their derivatives to avian embryos.

    Science.gov (United States)

    Goldstein, Ronald S

    2010-09-01

    Xenografting of normal and transformed mammalian tissues and cells to chick embryos has been performed for almost 100 years. Embryonic stem cells, derived more than 25 years ago from murine, and more than 10 years ago from human blastocysts, have transformed many fields of biological research. There is a growing body of studies combining these two widely-used experimental systems. This review surveys those reports in which murine or human embryonic stem cells, or differentiated derivatives of these pluripotent stem cells, were transplanted to embryonated chick eggs. Many of these studies have utilized the unique characteristics of both experimental models to obtain answers to developmental questions that are difficult or impossible to approach with xenografting to adult rodents or tissue culture-only techniques.

  5. Digital filter technology and its application to geomagnetic pulsations in Antarctica

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Digital filter technology is an important method in study of geomagnetic pulsations in Antarctica. The signals received by pulsation magnetometer on the ground include various types of magnetic pulsations. Some types of pulsations or some frequency hands of pulsations can be extracted from the signals by means of digital filter technology because types of pulsations are defined according to their frequency range. In this paper usual digital filter technology is provided for study of magnetic pulsations in Antarctica and some examples are introduced.

  6. Anasarca and myopathy in ostrich chicks.

    Science.gov (United States)

    Philbey, A W; Button, C; Gestier, A W; Munro, B E; Glastonbury, J R; Hindmarsh, M; Love, S C

    1991-07-01

    Twenty ostrich chicks that died at, or within, 1 week after hatching were examined from 7 farms with poor (43 to 75%) hatchability. All chicks had anasarca and 15 had mild, generalised, acute degenerative changes in the complexus and pelvic limb muscles. One had fibrinoid degeneration of arterioles. Biochemical examinations produced no evidence of deficiencies of selenium, vitamin A or vitamin E. The syndrome was related to high relative humidity during incubation. Malpositioning also was a cause of embryo mortality.

  7. Endosulfan Impacts on the Developing Chick Embryos: Morphological, Morphometric and Skeletal Changes

    Directory of Open Access Journals (Sweden)

    Y.M. Mobarak

    2011-01-01

    Full Text Available This study aims to explore the effects of the organochlorine pesticide Endosulfan (35% EC on the developing chick embryos. After 24 h of eggs incubation, a single dose of 7 or 14 or 21 mg Endosulfan/egg was administered through the egg air space at once. The eggs were opened on embryonic days 6 and 12 and the embryos were evaluated for viability, wet body weights and various morphological, morphometric and skeletal changes. Skeletons of 12-day-old embryos were stained by alizarin red S and Alcian blue using a whole mount double cartilage and bone staining technique. Comparing the three doses with control and with each others, the high dose treatment resulted in statistically significant more embryonic deaths, while the mid-dose caused statistically more malformed embryos. On both embryonic days, the treated embryos exhibited dose-related growth retardation, as reflected by significant reductions of embryonic wet body weight, anterior-posterior head and crown-rump lengths as well as generalized edema and hematomas formations. Also, on embryonic day 12 significant reductions of beak length, eye diameters and measurements of wing and hind-limb parts were recorded. Abnormal survivors showed high percentages of limb deformities (as limb paralysis, clinodactyly, flexion and shortness of limbs or digits, microphthalmia, microtia and omphalocele. The skeleton of treated embryos showed anomalies and incomplete chondrification and/or ossification of some skull parts (interorbital septum, frontals, parietals, palatines and external auditory apertures, cervicals, scapulae, ribs, sacrals and caudals. These findings suggest that Endosulfan exhibits embryotoxic and teratogenic effects on the developing chick embryos in terms of growth retardation, external and skeletal malformations.

  8. Early expression of hypocretin/orexin in the chick embryo brain.

    Directory of Open Access Journals (Sweden)

    Kyle E Godden

    Full Text Available Hypocretin/Orexin (H/O neuropeptides are released by a discrete group of neurons in the vertebrate hypothalamus which play a pivotal role in the maintenance of waking behavior and brain state control. Previous studies have indicated that the H/O neuronal development differs between mammals and fish; H/O peptide-expressing cells are detectable during the earliest stages of brain morphogenesis in fish, but only towards the end of brain morphogenesis (by ∼ 85% of embryonic development in rats. The developmental emergence of H/O neurons has never been previously described in birds. With the goal of determining whether the chick developmental pattern was more similar to that of mammals or of fish, we investigated the emergence of H/O-expressing cells in the brain of chick embryos of different ages using immunohistochemistry. Post-natal chick brains were included in order to compare the spatial distribution of H/O cells with that of other vertebrates. We found that H/O-expressing cells appear to originate from two separate places in the region of the diencephalic proliferative zone. These developing cells express the H/O neuropeptide at a comparatively early age relative to rodents (already visible at 14% of the way through fetal development, thus bearing a closer resemblance to fish. The H/O-expressing cell population proliferates to a large number of cells by a relatively early embryonic age. As previously suggested, the distribution of H/O neurons is intermediate between that of mammalian and non-mammalian vertebrates. This work suggests that, in addition to its roles in developed brains, the H/O peptide may play an important role in the early embryonic development of non-mammalian vertebrates.

  9. Myostatin promotes the terminal differentiation of embryonic muscle progenitors.

    Science.gov (United States)

    Manceau, Marie; Gros, Jérôme; Savage, Kathleen; Thomé, Virginie; McPherron, Alexandra; Paterson, Bruce; Marcelle, Christophe

    2008-03-01

    Myostatin, a TGF-beta family member, is an important regulator of adult muscle size. While extensively studied in vitro, the mechanisms by which this molecule mediates its effect in vivo are poorly understood. We addressed this question using chick and mouse embryos. We show that while myostatin overexpression in chick leads to an exhaustion of the muscle progenitor population that ultimately results in muscle hypotrophy, myostatin loss of function in chick and mouse provokes an expansion of this population. Our data demonstrate that myostatin acts in vivo to regulate the balance between proliferation and differentiation of embryonic muscle progenitors by promoting their terminal differentiation through the activation of p21 and MyoD. Previous studies have suggested that myostatin imposes quiescence on muscle progenitors. Our data suggest that myostatin's effect on muscle progenitors is more complex than previously realized and is likely to be context-dependent. We propose a novel model for myostatin mode of action in vivo, in which myostatin affects the balance between proliferation and differentiation of embryonic muscle progenitors by enhancing their differentiation.

  10. A Chick Embryo in-Vitro Model of Knee Morphogenesis

    Directory of Open Access Journals (Sweden)

    Edward K. Rodriguez

    2016-04-01

    Full Text Available Background: In this feasibility study, a mechanically loaded in-vitro tissue culture model of joint morphogenesis using the isolated lower extremity of the 8 day old chick embryo was developed to assess the effects of mechanical loading on joint morphogenesis. Methods: The developed in-vitro system allows controlled flexion and extension of the chick embryonic knee with a range of motion of 20 degrees from a resting position of 90-100 degrees of flexion. Joint morphogenesis at 2, 3, 4 and 7 days of culture was assessed by histology and micro MRI in 4 specimen types: undisturbed in-ovo control embryos, in-ovo paralyzed embryos, in-vitro unloaded limb cultures, and in-vitro loaded limb cultures. Relative glycosaminoglycan (GAG concentration across the joint was assessed with an MRI technique referred to as dGEMRIC (delayed gadolinium enhanced MRI of cartilage where T1 is proportional to glycosaminoglycan concentration. Results: Average T1 over the entire tissue image for the normal control (IC knee was 480 msec; for the 4 day loaded specimen average T1 was 354 msec; and for the 7 day loaded specimens T1 was 393 msec. The 4 day unloaded specimen had an average T1 of 279 msec while the 7 day unloaded specimen had an average T1 of 224 msec. The higher T1 values in loaded than unloaded specimens suggest that more glycosaminoglycan is produced in the loaded culture than in the unloaded preparation. Conclusion: Isolated limb tissue cultures under flexion-extension load can be viable and exhibit more progression of joint differentiation and glycosaminoglycan production than similarly cultured but unloaded specimens. However, when compared with controls consisting of intact undisturbed embryos in-ovo , the isolated loaded limbs in culture do not demonstrate equivalent amounts of absolute growth or joint differentiation.

  11. Stellar Pulsations in Beyond Horndeski Gravity Theories

    CERN Document Server

    Sakstein, Jeremy; Koyama, Kazuya

    2016-01-01

    Theories of gravity in the beyond Horndeski class recover the predictions of general relativity in the solar system whilst admitting novel cosmologies, including late-time de Sitter solutions in the absence of a cosmological constant. Deviations from Newton's law are predicted inside astrophysical bodies, which allow for falsifiable, smoking-gun tests of the theory. In this work we study the pulsations of stars by deriving and solving the wave equation governing linear adiabatic oscillations to find the modified period of pulsation. Using both semi-analytic and numerical models, we perform a preliminary survey of the stellar zoo in an attempt to identify the best candidate objects for testing the theory. Brown dwarfs and Cepheid stars are found to be particularly sensitive objects and we discuss the possibility of using both to test the theory.

  12. Flow induced pulsations in pipe systems

    Science.gov (United States)

    Bruggeman, Jan Cornelis

    1987-12-01

    The aeroacoustic behavior of a low Mach number, high Reynolds number flow through a pipe with closed side branches was investigated. Sound is generated by coherent structures of concentrated vorticity formed periodically in the separated flow in the T-shaped junctions of side branches and the main pipe. The case of moderate pulsation amplitudes was investigated. It appears that the vortical flow in a T-joint is an aeroacoustic source of constant strength when acoustic energy losses due to radiation and friction are small but not negligible. When acoustic energy losses due to radiation and friction are negligible, the nonlinear character of vortex damping is the amplitude limiting mechanism. It is stressed that aeroacoustic sources should not be neglected in studies of the response of a piping lay-out with flow to, e.g., the pulsating output of a compressor.

  13. Stellar pulsations in beyond Horndeski gravity theories

    Science.gov (United States)

    Sakstein, Jeremy; Kenna-Allison, Michael; Koyama, Kazuya

    2017-03-01

    Theories of gravity in the beyond Horndeski class recover the predictions of general relativity in the solar system whilst admitting novel cosmologies, including late-time de Sitter solutions in the absence of a cosmological constant. Deviations from Newton's law are predicted inside astrophysical bodies, which allow for falsifiable, smoking-gun tests of the theory. In this work we study the pulsations of stars by deriving and solving the wave equation governing linear adiabatic oscillations to find the modified period of pulsation. Using both semi-analytic and numerical models, we perform a preliminary survey of the stellar zoo in an attempt to identify the best candidate objects for testing the theory. Brown dwarfs and Cepheid stars are found to be particularly sensitive objects and we discuss the possibility of using both to test the theory.

  14. Pulsating White Dwarf Stars and Precision Asteroseismology

    CERN Document Server

    Winget, D E

    2008-01-01

    Galactic history is written in the white dwarf stars. Their surface properties hint at interiors composed of matter under extreme conditions. In the forty years since their discovery, pulsating white dwarf stars have moved from side-show curiosities to center stage as important tools for unraveling the deep mysteries of the Universe. Innovative observational techniques and theoretical modeling tools have breathed life into precision asteroseismology. We are just learning to use this powerful tool, confronting theoretical models with observed frequencies and their time rate-of-change. With this tool, we calibrate white dwarf cosmochronology; we explore equations of state; we measure stellar masses, rotation rates, and nuclear reaction rates; we explore the physics of interior crystallization; we study the structure of the progenitors of Type Ia supernovae, and we test models of dark matter. The white dwarf pulsations are at once the heartbeat of galactic history and a window into unexplored and exotic physics.

  15. Pulsating White Dwarf Stars and Precision Asteroseismology

    Science.gov (United States)

    Winget, D. E.; Kepler, S. O.

    2008-09-01

    Galactic history is written in the white dwarf stars. Their surface properties hint at interiors composed of matter under extreme conditions. In the forty years since their discovery, pulsating white dwarf stars have moved from side-show curiosities to center stage as important tools for unraveling the deep mysteries of the Universe. Innovative observational techniques and theoretical modeling tools have breathed life into precision asteroseismology. We are just learning to use this powerful tool, confronting theoretical models with observed frequencies and their time rate-of-change. With this tool, we calibrate white dwarf cosmochronology; we explore equations of state; we measure stellar masses, rotation rates, and nuclear reaction rates; we explore the physics of interior crystallization; we study the structure of the progenitors of Type Ia supernovae, and we test models of dark matter. The white dwarf pulsations are at once the heartbeat of galactic history and a window into unexplored and exotic physics.

  16. Pulsating Radio Sources near the Crab Nebula.

    Science.gov (United States)

    Staelin, D H; Reifenstein, E C

    1968-12-27

    Two new pulsating radio sources, designated NP 0527 and NP 0532, were found near the Crab Nebula and could be coincident with it. Both sources are sporadic, and no periodicities are evident. The pulse dispersions indicate that 1.58 +/- 0.03 and 1.74 +/- 0.02 x 10(20) electrons per square centimeter lie in the direction of NP 0527 and NP 0532, respectively.

  17. Migratory mechanisms of chick primordial germ cells toward gonadal anlage.

    Science.gov (United States)

    Kuwana, T; Rogulska, T

    1999-07-01

    After appearing at the germinal crescent region, chick primordial germ cells (PGCs) migrate toward the presumptive gonads (pG) till stage 19 (Hamburger and Hamilton, 1951). This study seeks to elucidate the roles of passive and active factors in the PGC-migration, physical trapping of circulating PGCs by the capillary network and PGC attraction by chemotactic factor from presumptive gonads. Firstly, latex beads/pollens (the same size or larger than PGCs) were injected into the embryonic bloodstream at stage 13-19 (when PGCs are in the migrating and settlement phase to the presumptive gonad) in ovo in order to determine whether the PGCs passively reach pG. Most of such particles accumulated in the head region (60%), whereas the remainder did the same in the gonadal region (23% at the peak) at stage 16 when both the head and gonadal regions are rich in capillary plexus. After 3 days, most particles in the gonadal region were located at the angles of dorsal mesentery near the developing gonads where many extra-gonadal PGCs had been located, and a few particles were detected close to the gonad. These results suggest that one of the mechanisms of PGC-migration to the developing gonads is an autonomous trapping of PGCs by the capillary network quite close to the germinal epithelium (GE) and passive translocation by morphogenetic movement. Secondly, the attraction for PGCs by the gonadal anlage proper was examined in ovo using chick and quail embryos. Grafts of quail gonadal anlage containing gonadal epithelium and neighbouring mesenchymal tissue were excised from the quail embryo at stages 12 to 16 (staging by Zacchei, 1961). With the aims of eliminating the influence of surrounding tissue, the quail graft was ectopically transplanted into the posterior to the optic vesicle of 8 to 17 somite chick embryo from the point of a posterior region to the auditory vesicle by a fine tungsten needle under the illumination by the method of Hara (1971). Then the region posterior to

  18. Discovery of five new massive pulsating white dwarf stars

    Science.gov (United States)

    Castanheira, B. G.; Kepler, S. O.; Kleinman, S. J.; Nitta, A.; Fraga, L.

    2013-03-01

    Using the SOuthern Astrophysical Research telescope (SOAR) Optical Imager at the SOAR 4.1 m telescope, we report on the discovery of five new massive pulsating white dwarf stars. Our results represent an increase of about 20 per cent in the number of massive pulsators. We have detected both short and long periods, low and high amplitude pulsation modes, covering the whole range of the ZZ Ceti instability strip. In this paper, we present a first seismological study of the new massive pulsators based on the few frequencies detected. Our analysis indicates that these stars have masses higher than average, in agreement with the spectroscopic determinations. In addition, we study for the first time the ensemble properties of the pulsating white dwarf stars with masses above 0.8 M⊙. We found a bimodal distribution of the main pulsation period with the effective temperature for the massive DAVs, which indicates mode selection mechanisms.

  19. The Onset of Chaos in Pulsating Variable Stars

    CERN Document Server

    Turner, David G; Percy, J R; Abdel-Latif, Mohamed Abdel-Sabour

    2011-01-01

    Random changes in pulsation period occur in cool pulsating Mira variables, Type A, B, and C semiregular variables, RV Tauri variables, and in most classical Cepheids. The physical processes responsible for such fluctuations are uncertain, but presumably originate in temporal modifications of the envelope convection in such stars. Such fluctuations are seemingly random over a few pulsation cycles of the stars, but are dominated by the regularity of the primary pulsation over the long term. The magnitude of stochasticity in pulsating stars appears to be linked directly to their dimensions, although not in simple fashion. It is relatively larger in M supergiants, for example, than in short-period Cepheids, but is common enough that it can be detected in visual observations for many types of pulsating stars. Although chaos was discovered in such stars 80 years ago, detection of its general presence in the group has only been possible in recent studies.

  20. SuperWASP observations of pulsating Am stars

    CERN Document Server

    Smalley, B; Smith, A M S; Fossati, L; Anderson, D R; Barros, S C C; Butters, O W; Cameron, A Collier; Christian, D J; Enoch, B; Faedi, F; Haswell, C A; Hellier, C; Holmes, S; Horne, K; Kane, S R; Lister, T A; Maxted, P F L; Norton, A J; Parley, N; Pollacco, D; Simpson, E K; Skillen, I; Southworth, J; Street, R A; West, R G; Wheatley, P J; Wood, P L

    2011-01-01

    We have studied over 1600 Am stars at a photometric precision of 1 mmag with SuperWASP photometric data. Contrary to previous belief, we find that around 200 Am stars are pulsating delta Sct and gamma Dor stars, with low amplitudes that have been missed in previous, less extensive studies. While the amplitudes are generally low, the presence of pulsation in Am stars places a strong constraint on atmospheric convection, and may require the pulsation to be laminar. While some pulsating Am stars have been previously found to be delta Sct stars, the vast majority of Am stars known to pulsate are presented in this paper. They will form the basis of future statistical studies of pulsation in the presence of atomic diffusion.

  1. Ejecting chick cheats: a changing paradigm?

    Directory of Open Access Journals (Sweden)

    Grim Tomáš

    2011-06-01

    Full Text Available Abstract Evolutionary arms-races between avian brood parasites and their hosts have typically resulted in some spectacular adaptations, namely remarkable host ability to recognize and reject alien eggs and, in turn, sophisticated parasite egg mimicry. In a striking contrast to hosts sometimes rejecting even highly mimetic eggs, the same species typically fail to discriminate against highly dissimilar parasite chicks. Understanding of this enigma is still hampered by the rarity of empirical tests - and consequently evidence - for chick discrimination. Recent work on Australian host-parasite systems (Gerygone hosts vs. Chalcites parasites, increased not only the diversity of hosts showing chick discrimination, but also discovered an entirely novel host behavioural adaptation. The hosts do not desert parasite chicks (as in all previously reported empirical work but physically remove living parasites from their nests. Here, I briefly discuss these exciting findings and put them in the context of recent empirical and theoretical work on parasite chick discrimination. Finally, I review factors responsible for a relatively slow progress in this research area and suggest most promising avenues for future research.

  2. A search for low-metallicity pulsating B stars

    Science.gov (United States)

    Engelbrecht, Chris; Kgoadi, Refilwe; Frescura, Fabio

    2017-09-01

    We report on some recent results from a long-term UBVI survey of various fields in the Large Magellanic Cloud (LMC), which is aimed at identifying and classifying pulsating B stars in the selected LMC fields. Difference Imaging Analysis shows a clear advantage over conventional PSF fitting. Tentative indications have been found of a varying incidence of pulsation amplitudes (and, by inference, of metal content of the pulsators) across the LMC bar.

  3. Ontogeny of circadian clock gene expression in the pineal and the suprachiasmatic nucleus of chick embryo.

    Science.gov (United States)

    Okabayashi, Naritoshi; Yasuo, Shinobu; Watanabe, Miwa; Namikawa, Takao; Ebihara, Shizufumi; Yoshimura, Takashi

    2003-11-14

    Avian circadian rhythms are regulated by a multiple oscillatory system consisting of the pineal, the suprachiasmatic nucleus (SCN) and the eye. In the present study, ontogeny of circadian clock in the pineal and the SCN of chick embryo was examined using Per2 expression as a marker. A daily rhythmicity of Per2 expression was first detectable at embryonic day (ED) 18 in the pineal and at ED 16 in the SCN under light-dark (LD) cycles. The amplitude of the rhythmicity increased during the development. In contrast, little expression was observed during the development in constant darkness. These results suggest that although circadian clock matures by the end of the embryonic life in chicken, LD cycles are required for the expression of the Per2.

  4. Adenylyl Cyclase Signaling in the Developing Chick Heart: The Deranging Effect of Antiarrhythmic Drugs

    Directory of Open Access Journals (Sweden)

    Lucie Hejnova

    2014-01-01

    Full Text Available The adenylyl cyclase (AC signaling system plays a crucial role in the regulation of cardiac contractility. Here we analyzed the key components of myocardial AC signaling in the developing chick embryo and assessed the impact of selected β-blocking agents on this system. Application of metoprolol and carvedilol, two commonly used β-blockers, at embryonic day (ED 8 significantly downregulated (by about 40% expression levels of AC5, the dominant cardiac AC isoform, and the amount of Gsα protein at ED9. Activity of AC stimulated by forskolin was also significantly reduced under these conditions. Interestingly, when administered at ED4, these drugs did not produce such profound changes in the myocardial AC signaling system, except for markedly increased expression of Giα protein. These data indicate that β-blocking agents can strongly derange AC signaling during the first half of embryonic heart development.

  5. l-Leucine acts as a potential agent in reducing body temperature at hatching and affords thermotolerance in broiler chicks.

    Science.gov (United States)

    Han, Guofeng; Yang, Hui; Bahry, Mohammad A; Tran, Phuong V; Do, Phong H; Ikeda, Hiromi; Furuse, Mitsuhiro; Chowdhury, Vishwajit S

    2017-02-01

    Thermal manipulation (TM) of incubation temperature causes metabolic alterations and contributes to improving thermotolerance in chicks post hatching. However, there has been no report on amino acid metabolism during TM and the part it plays in thermotolerance. In this study, we therefore first analyzed free amino acid concentrations in the embryonic brain and liver during TM (38.6°C, 6h/d during embryonic day (ED) 10 to ED 18). It was found that leucine (Leu), phenylalanine and lysine were significantly decreased in the embryonic brain and liver. We then chose l-Leu and other branched-chain amino acids (l-isoleucine (L-Ile) and l-valine (l-Val)) for in ovo injection on ED 7 to reveal their roles in thermoregulation, growth, food intake and thermotolerance in chicks. It was found that in ovo injection of l-Leu, but not of l-Ileu or l-Val, caused a significant decline in body temperature at hatching and increased food intake and body weight gain in broiler chicks. Interestingly, in ovo injection of l-Leu resulted in the acquisition of thermotolerance under high ambient temperature (35±1°C for 180min) in comparison with the control thermoneutral temperature (28±1°C for 180min). These results indicate that the free amino acid concentrations during embryogenesis were altered by TM. l-Leu administration in eggs caused a reduction in body temperature at hatching, and afforded thermotolerance in heat-exposed young chicks, further suggesting that l-Leu may be one of the key metabolic factors involved in controlling body temperature in embryos, as well as in producing thermotolerance after hatching.

  6. On the pulsation and evolutionary properties of helium burning radially pulsating variables

    Science.gov (United States)

    Bono, G.; Pietrinferni, A.; Marconi, M.; Braga, V. F.; Fiorentino, G.; Stetson, P. B.; Buonanno, R.; Castellani, M.; Dall'Ora, M.; Fabrizio, M.; Ferraro, I.; Giuffrida, G.; Iannicola, G.; Marengo, M.; Magurno, D.; Martinez-Vazquez, C. E.; Matsunaga, N.; Monelli, M.; Neeley, J.; Rastello, S.; Salaris, M.; Short, L.; Stellingwerf, R. F.

    2016-05-01

    We discuss pulsation and evolutionary properties of low- (RR Lyrae, Type II Cepheids) and intermediate-mass (Anomalous Cepheids) radial variables. We focus our attention on the topology of the instability strip and the distribution of the quoted variables in the Hertzsprung-Russell diagram. We discuss their evolutionary status and the dependence on the metallicity. Moreover, we address the diagnostics (period derivative, difference in luminosity, stellar mass) that can provide solid constraints on their progenitors and on the role that binarity and environment have in shaping their current pulsation characteristics. Finally, we briefly outline their use as standard candles.

  7. Expression analysis of Shh signaling members in early stages of chick lung development.

    Science.gov (United States)

    Moura, Rute Silva; Silva-Gonçalves, Carla; Vaz-Cunha, Patrícia; Correia-Pinto, Jorge

    2016-10-01

    Lung organogenesis is guided by epithelial-mesenchymal interactions that coordinate cellular events responsible for the formation of the respiratory system. Several signaling pathways have been implicated in this process; among them, sonic hedgehog (Shh) signaling has emerged as a crucial regulator of branching morphogenesis in the mammalian lung. Canonical Shh signaling requires the presence of patched (Ptch) and smoothened (Smo) transmembrane receptors in order to induce the activation of glioblastoma (Gli) zinc finger transcription factors that are the true effectors of the pathway. Signal transduction is finely regulated by Ptch1, Gli, and Hhip (hedgehog-interacting protein). The present work characterizes, for the first time, the expression pattern of shh, ptch1, smo, gli1, and hhip in early stages of the embryonic chick lung. In situ hybridization studies revealed that these genes are expressed in the same cellular compartments as their mammalian counterparts, although their proximo-distal distribution is slightly changed. Moreover, the molecular interactions between fibroblast growth factor (FGF) and Shh signaling pathway were assessed, in vitro, by grafting beads soaked in SU5402 (an FGF receptor inhibitor). In the chick lung, Shh signaling seems to have some features that are species specific since shh is not a downstream target of FGF signaling. Nonetheless and despite the observed differences, these findings suggest a role for Shh signaling in the epithelial-mesenchymal interactions that control chick lung morphogenesis.

  8. From the Cover: Exposing Imidacloprid Interferes With Neurogenesis Through Impacting on Chick Neural Tube Cell Survival.

    Science.gov (United States)

    Liu, Meng; Wang, Guang; Zhang, Shi-Yao; Zhong, Shan; Qi, Guo-Long; Wang, Chao-Jie; Chuai, Manli; Lee, Kenneth Ka Ho; Lu, Da-Xiang; Yang, Xuesong

    2016-09-01

    As a neonicotinoid pesticide, imidacloprid is widely used to control insects in agriculture and fleas on domestic animals. However, it is not known whether imidacloprid exposure negatively affects neurogenesis during embryonic development. In this study, using a chick embryo model, we investigated the effects of imidacloprid exposure on neurogenesis at the earliest stage and during late-stage embryo development. Exposing HH0 chick embryos to imidacloprid in EC culture caused neural tube defects (NTDs) and neuronal differentiation dysplasia as determined by NF/Tuj1 labeling. Furthermore, we found that F-actin accumulation on the apical side of the neural tube was suppressed by exposure to imidacloprid, and the expression of BMP4 and Shh on the dorsal and ventral sides of the neural tubes, respectively, were also reduced, which in turn affects the dorsolateral hinge points during bending of the neural plate. In addition, exposure to imidacloprid reduced cell proliferation and increased cell apoptosis, as determined by pHIS3 labeling and TUNEL staining, respectively, also contributing to the malformation. We obtained similar results in late-stage embryos exposed to imidacloprid. Finally, a bioinformatics analysis was employed to determine which genes identified in this study were involved in NTDs. The experimental evidence and bioinformatics analysis suggested that imidacloprid exposure during chick embryo development could increase the risk of NTDs and neural dysplasia.

  9. Control temperature of young chicks to reduce mortality

    NARCIS (Netherlands)

    Lourens, A.; Kuijpers, M.

    2002-01-01

    Individual chicks may have different environmental temperature demands. The trick is to provide every chick with the right body temperature. By measuring individual chick temperatures, hatchery staff and broiler growers or layer producers are better able to provide the right environmental temperatur

  10. Hydrogen peroxide potentiates organophosphate toxicosis in chicks

    Directory of Open Access Journals (Sweden)

    Banan K. Al-Baggou

    2011-11-01

    Full Text Available Objective: The purpose of the present study was to examine the effect of hydrogen peroxide(H2O2 on the acute toxicity of organophosphate insecticides dichlorvos and diazinon and their inhibitoryactions on plasma, brain and liver cholinesterase activities. Material and Methods: H2O2 was given indrinking water (0.5% v/v for 2 weeks in unsexed day old chicks, a regimen known to induce oxidativestress in this species. A control group received drinking tap water. All experiments were conducted onthe chicks at the age of 15 days after exposure to H2O2. The acute (24 h oral LD50 values of dichlorvosand diazinon in the insecticidal preparations as determined by the up-and-down method in the controlchicks were 9.4 and 15.6 mg/kg, respectively. Results: The poisoned chicks manifested signs ofcholinergic toxicosis within one hour after the dosing including salivation, lacrimation, gasping, frequentdefecation, drooping of wings, tremors, convulsions and recumbency. The acute (24 h oral LD50 valuesof dichlorvos and diazinon in chicks provided with H2O2 were reduced to 3.5 and 6.5 mg/kg, by 63 and58%, respectively when compared to respective control LD50 values. The intoxicated chicks also showedcholinergic signs of toxicosis as described above. Plasma, brain and liver cholinesterase activities of thechicks exposed to H2O2 were significantly lower than their respective control (H2O values by 25, 28 and27%, respectively. Oral dosing of chicks with dichlorvos at 3 mg/kg significantly inhibited cholinesteraseactivities in the plasma, brain and liver of both control (42-67% and H2O2-treated (15-59% chicks.Diazinon at 5 mg/kg, orally also inhibited cholinesterase activities in the plasma, brain and liver of bothcontrol (36-66% and H2O2-treated (15-30% chicks. In the H2O2 groups, dichlorvos inhibition of livercholinesterase activity and diazinon inhibition of liver and brain cholinesterase activities weresignificantly lesser than those of the respective values of

  11. Expression pattern of LINGO-1 in the developing nervous system of the chick embryo.

    Science.gov (United States)

    Okafuji, Tatsuya; Tanaka, Hideaki

    2005-12-01

    We isolated a chick homologue of LINGO-1 (cLINGO-1), a novel component of the Nogo-66 receptor (NgR)/p75 neurotrophin receptor (NTR) signaling complex, and examined the expression of cLINGO-1 in the developing brain and spinal cord of the chick embryo by in situ hybridization and immunohistochemistry. cLINGO-1 was expressed broadly in the spinal cord, including the ventral portion of the ventricular zone, and motor neurons. cLINGO-1 was also expressed in the dorsal root ganglion and boundary cap cells at dorsal and ventral roots. In the early embryonic brain, cLINGO-1 was first expressed in the prosencephalon and the ventral mesencephalon, and later in the telencephalon, the rostral part of the mesencephalon and some parts of the hindbrain. cLINGO-1 was also expressed in the ventral part of the neural retina and trigeminal and facial nerves. We also found that cLINGO-1, cNgR1 and p75NTR were expressed in overlapped patterns in the spinal cord and the dorsal root ganglion, but that these genes were expressed in distinct patterns in the early embryonic brain.

  12. The chick embryo as an experimental system for melanoma cell invasion.

    Directory of Open Access Journals (Sweden)

    Christian Busch

    Full Text Available BACKGROUND: A primary cutaneous melanoma will not kill the patient, but its metastases. Since in vitro studies on melanoma cells in 2-D cultures do often not reflect reality, 3-D models might come closer to the physiological situation in the patient during cancer initiation and progression. METHODOLOGY/PRINCIPAL FINDINGS: Here, we describe the chick embryo model for in vivo studies of melanoma cell migration and invasion. After transplantation of neural crest-derived melanoma cells into the neural tube, the melanoma cells resume neural crest cell migration along the medial and lateral pathways and finally undergo apoptosis in the target areas. Upon transplantation into ectopic areas such as the hindbrain or the optic cup malignant invasion and local tissue destruction occurs. In contrast, melanocytes are not able to spontaneously resume neural crest cell migration. However, malignant invasion can be induced in melanocytes by pre-treatment with the TGF-beta family members bone morphegenetic protein-2 or nodal. Transplantation of MCF7 breast cancer cells yields a different growth pattern in the rhombencephalon than melanoma cells. CONCLUSIONS/SIGNIFICANCE: The chick embryo model is a feasible, cost-effective in vivo system to study invasion by cancer cells in an embryonic environment. It may be useful to study invasive behavior induced by embryonic oncogenes and for targeted manipulation of melanoma or breast cancer cells aiming at ablation of invasive properties.

  13. Multidimensional modelling of classical pulsating stars

    CERN Document Server

    Muthsam, Herbert J

    2016-01-01

    After an overview of general aspects of modelling the pulsation- convection interaction we present reasons why such simulations (in multidimensions) are needed but, at the same time, pose a considerable challenge. We then discuss, for several topics, what insights multidimensional simulations have either already provided or can be expected to yield in the future. We finally discuss properties of our ANTARES code. Many of these features can be expected to be characteristic of other codes which may possibly be applied to these physical questions in the foreseeable future.

  14. High-Precision Spectroscopy of Pulsating Stars

    CERN Document Server

    Aerts, C; Desmet, M; Carrier, F; Zima, W; Briquet, M; De Ridder, J

    2007-01-01

    We review methodologies currently available to interprete time series of high-resolution high-S/N spectroscopic data of pulsating stars in terms of the kind of (non-radial) modes that are excited. We illustrate the drastic improvement of the detection treshold of line-profile variability thanks to the advancement of the instrumentation over the past two decades. This has led to the opportunity to interprete line-profile variations with amplitudes of order m/s, which is a factor 1000 lower than the earliest line-profile time series studies allowed for.

  15. RZ Cassiopeia: Eclipsing Binary with Pulsating Component

    CERN Document Server

    Golovin, A

    2007-01-01

    We report time-resolved VR-band CCD photometry of the eclipsing binary RZ Cas obtained with 38-cm Cassegrain telescope at the Crimean Astrophysical Observatory during July 2004 - October 2005. Obtained lightcurves clearly demonstrates rapid pulsations with the period about 22 minutes. Periodogram analysis of such oscillations also is reported. On the 12, January, 2005 we observed rapid variability with higher amplitude (~0.^m 1) that, perhaps, may be interpreted as high-mass-transfer-rate event and inhomogeneity of accretion stream. Follow-up observations (both, photometric and spectroscopic) of RZ Cas are strictly desirable for more detailed study of such event.

  16. Pulsations, interpulsations, and sea-floor spreading.

    Science.gov (United States)

    Pessagno, E. A., Jr.

    1973-01-01

    It is postulated that worldwide transgressions (pulsations) and regressions (interpulsations) through the course of geologic time are related to the elevation and subsidence of oceanic ridge systems and to sea-floor spreading. Two multiple working hypotheses are advanced to explain major transgressions and regressions and the elevation and subsidence of oceanic ridge systems. One hypothesis interrelates the sea-floor spreading hypothesis to the hypothesis of sub-Mohorovicic serpentinization. The second hypothesis relates the sea-floor spreading hypothesis to a hypothesis involving thermal expansion and contraction.

  17. First Kepler results on compact pulsators - VII. Pulsating subdwarf B stars detected in the second half of the survey phase

    Science.gov (United States)

    Baran, A. S.; Kawaler, S. D.; Reed, M. D.; Quint, A. C.; O'Toole, S. J.; Østensen, R. H.; Telting, J. H.; Silvotti, R.; Charpinet, S.; Christensen-Dalsgaard, J.; Still, M.; Hall, J. R.; Uddin, K.

    2011-07-01

    We present five new pulsating subdwarf B (sdB) stars discovered by the Kepler spacecraft during the asteroseismology survey phase. We perform time series analysis on the nearly continuous month-long Kepler data sets of these five objects; these data sets provide nearly alias-free time series photometry at unprecedented precision. Following an iterative pre-whitening process, we derive the pulsational frequency spectra of these stars, separating out artefacts of known instrumental origin. We find that these new pulsating sdB stars are multiperiodic long-period pulsators of the V1093 Her type, with the number of periodicities ranging from eight (KIC 8302197) to 53 (KIC 11558725). The frequencies and amplitudes are typical of g-mode pulsators of this type. We do not find any evidence for binarity in the five stars from their observed pulsation frequencies. As these are g-mode pulsators, we briefly looked for period spacings for mode identification and found average spacings of about 260 and 145 s. This may indicate l= 1 and 2 patterns. Some modes may show evidence of rotational splitting. These discoveries complete the list of compact pulsators found in the survey phase. Of the 13 compact pulsators, only one star was identified as a short-period (p-mode) V361 Hya pulsator, while all other new pulsators turned out to be V1093 Her class objects. Among the latter objects, two of them seemed to be pure V1093 Her while the others show additional low-amplitude peaks in the p-mode frequency range, suggesting their hybrid nature. Authenticity of these peaks will be tested with longer runs currently under analysis.

  18. The birth of quail chicks after intracytoplasmic sperm injection.

    Science.gov (United States)

    Mizushima, Shusei; Hiyama, Gen; Shiba, Kogiku; Inaba, Kazuo; Dohra, Hideo; Ono, Tamao; Shimada, Kiyoshi; Sasanami, Tomohiro

    2014-10-01

    Intracytoplasmic sperm injection (ICSI) has been successfully used to produce offspring in several mammalian species including humans. However, ICSI has not been successful in birds because of the size of the egg and difficulty in mimicking the physiological polyspermy that takes place during normal fertilization. Microsurgical injection of 20 or more spermatozoa into an egg is detrimental to its survival. Here, we report that injection of a single spermatozoon with a small volume of sperm extract (SE) or its components led to the development and birth of healthy quail chicks. SE contains three factors - phospholipase Cζ (PLCZ), aconitate hydratase (AH) and citrate synthase (CS) - all of which are essential for full egg activation and subsequent embryonic development. PLCZ induces an immediate, transient Ca(2+) rise required for the resumption of meiosis. AH and CS are required for long-lasting, spiral-like Ca(2+) oscillations within the activated egg, which are essential for cell cycle progression in early embryos. We also found that co-injection of cRNAs encoding PLCZ, AH and CS support the full development of ICSI-generated zygotes without the use of SE. These findings will aid our understanding of the mechanism of avian fertilization and embryo development, as well as assisting in the manipulation of the avian genome and the production of transgenic and cloned birds.

  19. The Cepheid mass discrepancy and pulsation-driven mass loss

    NARCIS (Netherlands)

    Neilson, H.R.; Cantiello, M.; Langer, N.

    2011-01-01

    Context. A longstanding challenge for understanding classical Cepheids is the Cepheid mass discrepancy, where theoretical mass estimates using stellar evolution and stellar pulsation calculations have been found to differ by approximately 10−20%. Aims. We study the role of pulsation-driven mass loss

  20. Review and prospect of research on hydraulic pulsation attenuator

    Science.gov (United States)

    Shan, Chang-ji; Zhao, Qi-jun; Dai, Ting-ting; Bian, Yi-duo; Cai, Yan

    2017-09-01

    The pressure pulsation attenuator is able to decrease the fluid fluctuation of the hydraulic pump effectively, so it is widely used in construction machinery. This paper reviews the history and progresses of the research on the pressure pulsation attenuator in China and overseas, summarizes its two types: H-type rigid structure and built-in flexible material, meanwhile, discusses its future research area.

  1. Arginine requirement of starting broiler chicks.

    Science.gov (United States)

    Cuca, M; Jensen, L S

    1990-08-01

    Three experiments were conducted to estimate the arginine requirement of male broiler chicks from 0 to 3 wk of age. The experiments were conducted in battery brooders with wires floors, and the birds received water and feed ad libitum. In the first experiment, chicks were fed a diet based on corn, soybean meal, casein, and corn-gluten meal containing 3,200 kcal ME per kg and either 20 or 23% crude protein. Regression analysis indicated an arginine requirement of 1.22% for maximum growth rate and feed efficiency with the 20% protein diet. For chicks fed the 23% protein diet, neither growth rate nor feed efficiency was significantly different among the diets containing arginine ranging from 1.13 to 1.43%. In the second experiment, a basal diet was used containing 17.5% casein and 22.5% protein with arginine ranging from 1.03 to 1.43%. An arginine requirement of 1.18% for maximum body weight gain was estimated by regression analysis, but no significant response to arginine above the basal level was observed for feed efficiency. Performance of chicks fed the basal diet was somewhat reduced because of a difficulty with adherence of feed to the beaks. In a third experiment, three basal diets containing 21, 22, or 23% protein were formulated from practical ingredients without use of casein. The requirement for maximum growth rate and feed efficiency was estimated to be 1.24 to 1.28% for the three diets. The results of these investigations indicate that the arginine requirement for starting chicks suggested by the National Research Council in 1984 of 1.44% in diets containing 3,200 kcal ME per kg is too high for practical diets. The data presented here support an arginine requirement of 1.25%.

  2. Secular Evolution in Mira Variable Pulsations

    CERN Document Server

    Templeton, M R; Willson, L A

    2005-01-01

    Stellar evolution theory predicts that asymptotic giant branch stars undergo a series of short thermal pulses that significantly change their luminosity and mass on timescales of hundreds to thousands of years. Secular changes in these stars resulting from thermal pulses can be detected as measurable changes in period if the star is undergoing Mira pulsations. The American Association of Variable Star Observers (AAVSO) International Database currently contains visual data for over 1500 Mira variables. Light curves for these stars span nearly a century in some cases, making it possible to study the secular evolution of the pulsation behavior on these timescales. In this paper, we present the results of our study of period change in 547 Mira variables using data from the AAVSO. We find non-zero rates of period change, dlnP/dt, at the 2-sigma significance level in 57 of the 547 stars, at the 3-sigma level in 21 stars, and at the level of 6-sigma or greater in eight of the 547. The latter eight stars have been pr...

  3. Impulsively started, steady and pulsated annular inflows

    Science.gov (United States)

    Abdel-Raouf, Emad; Sharif, Muhammad A. R.; Baker, John

    2017-04-01

    A computational investigation was carried out on low Reynolds number laminar inflow starting annular jets using multiple blocking ratios and atmospheric ambient conditions. The jet exit velocity conditions are imposed as steady, unit pulsed, and sinusoidal pulsed while the jet surroundings and the far-field jet inlet upstream conditions are left atmospheric. The reason is to examine the flow behavior in and around the jet inlet under these conditions. The pulsation mode behavior is analyzed based on the resultant of the momentum and pressure forces at the entry of the annulus, the circulation and vortex formation, and the propulsion efficiency of the inflow jets. The results show that under certain conditions, the net force of inflow jets (sinusoidal pulsed jets in particular) could point opposite to the flow direction due to the adverse pressure drops in the flow. The propulsion efficiency is also found to increase with pulsation frequency and the sinusoidal pulsed inflow jets are more efficient than the unit pulsed inflow jets. In addition, steady inflow jets did not trigger the formation of vortices, while unit and sinusoidal pulsed inflow jets triggered the formation of vortices under a certain range of frequencies.

  4. Pulsating variable stars and large spectroscopic surveys

    Science.gov (United States)

    De Cat, Peter

    2017-09-01

    In the past decade, the research of pulsating variable stars has taken a giant leap forward thanks to the photometric measurements provided by space missions like Most, CoRoT, Kepler/K2, and Brite. These missions have provided quasi uninterrupted photometric time-series with an ultra-high quality and a total length that is not achievable from Earth. However, many of the success stories could not have been told without ground-based spectroscopic follow-up observations. Indeed, spectroscopy has some important assets as it can provide (more) accurate information about stellar parameters (like the effective temperature, surface gravity, metallicity, and abundances that are mandatory parameters for an in-depth asteroseismic study), the radial velocity (that is important for the detection of binaries and for the confirmation of cluster membership, if applicable), and the projected rotational velocity (that allows the study of the effects of rotation on pulsations). Fortunately, several large spectroscopic surveys are (becoming) available that can be used for these purposes. For some of these surveys, sub-projects have been initiated with the specific goal to complement space-based photometry. In this review, several spectroscopic surveys are introduced and compared with each other. We show that a large amount of spectroscopic data is (becoming) available for a large variety of objects.

  5. Computational model of miniature pulsating heat pipes.

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Mario J.; Givler, Richard C.

    2013-01-01

    The modeling work described herein represents Sandia National Laboratories (SNL) portion of a collaborative three-year project with Northrop Grumman Electronic Systems (NGES) and the University of Missouri to develop an advanced, thermal ground-plane (TGP), which is a device, of planar configuration, that delivers heat from a source to an ambient environment with high efficiency. Work at all three institutions was funded by DARPA/MTO; Sandia was funded under DARPA/MTO project number 015070924. This is the final report on this project for SNL. This report presents a numerical model of a pulsating heat pipe, a device employing a two phase (liquid and its vapor) working fluid confined in a closed loop channel etched/milled into a serpentine configuration in a solid metal plate. The device delivers heat from an evaporator (hot zone) to a condenser (cold zone). This new model includes key physical processes important to the operation of flat plate pulsating heat pipes (e.g. dynamic bubble nucleation, evaporation and condensation), together with conjugate heat transfer with the solid portion of the device. The model qualitatively and quantitatively predicts performance characteristics and metrics, which was demonstrated by favorable comparisons with experimental results on similar configurations. Application of the model also corroborated many previous performance observations with respect to key parameters such as heat load, fill ratio and orientation.

  6. Computational model of miniature pulsating heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Mario J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Givler, Richard C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-01-01

    The modeling work described herein represents Sandia National Laboratories (SNL) portion of a collaborative three-year project with Northrop Grumman Electronic Systems (NGES) and the University of Missouri to develop an advanced, thermal ground-plane (TGP), which is a device, of planar configuration, that delivers heat from a source to an ambient environment with high efficiency. Work at all three institutions was funded by DARPA/MTO; Sandia was funded under DARPA/MTO project number 015070924. This is the final report on this project for SNL. This report presents a numerical model of a pulsating heat pipe, a device employing a two phase (liquid and its vapor) working fluid confined in a closed loop channel etched/milled into a serpentine configuration in a solid metal plate. The device delivers heat from an evaporator (hot zone) to a condenser (cold zone). This new model includes key physical processes important to the operation of flat plate pulsating heat pipes (e.g. dynamic bubble nucleation, evaporation and condensation), together with conjugate heat transfer with the solid portion of the device. The model qualitatively and quantitatively predicts performance characteristics and metrics, which was demonstrated by favorable comparisons with experimental results on similar configurations. Application of the model also corroborated many previous performance observations with respect to key parameters such as heat load, fill ratio and orientation.

  7. The pulsation spectrum of VX Hydrae

    CERN Document Server

    Templeton, M R; Dvorak, S; Poklar, R; Butterworth, N; Gerner, H

    2009-01-01

    We present the results of a two-year, multisite observing campaign investigating the high-amplitude delta Scuti star VX Hydrae during the 2006 and 2007 observing seasons. The final data set consists of nearly 8500 V-band observations spanning HJD 2453763.6 to 2454212.7 (2006 January 28 to 2007 April 22). Separate analyses of the two individual seasons of data yield 25 confidently-detected frequencies common to both data sets, of which two are pulsation modes, and the remaining 23 are Fourier harmonics or beat frequencies of these two modes. The 2006 data set had five additional frequencies with amplitudes less than 1.5 mmag, and the 2007 data had one additional frequency. Analysis of the full 2006-2007 data set yields 22 of the 25 frequencies found in the individual seasons of data. There are no significant peaks in the spectrum other than these between 0 and 60 c/d. The frequencies of the two main pulsation modes derived from the 2006 and 2007 observing seasons individually do not differ at the level of 3-si...

  8. The Pulsation Spectrum of VX Hydrae

    Science.gov (United States)

    Templeton, M. R.; Samolyk, G.; Dvorak, S.; Poklar, R.; Butterworth, N.; Gerner, H.

    2009-10-01

    We present the results of a two-year, multisite observing campaign investigating the high-amplitude δ Scuti star VX Hydrae during the 2006 and 2007 observing seasons. The final data set consists of nearly 8500 V-band observations spanning HJD 2453763.6 to 2454212.7 (2006 January 28 to 2007 April 22). Separate analyses of the two individual seasons of data yield 25 confidently detected frequencies common to both data sets, of which two are pulsation modes, and the remaining 23 are Fourier harmonics or beat frequencies of these two modes. The 2006 data set had five additional frequencies with amplitudes less than 1.5 mmag, and the 2007 data had one additional frequency. Analysis of the full 2006–2007 data set yields 22 of the 25 frequencies found in the individual seasons of data. There are no significant peaks in the spectrum other than these between 0 and 60 cycles day-1. The frequencies of the two main pulsation modes derived from the 2006 and 2007 observing seasons individually do not differ at the level of 3σ, and thus we find no conclusive evidence for period change over the span of these observations. However, the amplitude of changed significantly between the two seasons, while the amplitude of remained constant; amplitudes of the Fourier harmonics and beat frequencies of f1 also changed. Similar behavior was seen in the 1950s, and it is clear that VX Hydrae undergoes significant amplitude changes over time.

  9. Determination of discharge during pulsating flow

    Science.gov (United States)

    Thompson, T.H.

    1968-01-01

    Pulsating flow in an open channel is a manifestation of unstable-flow conditions in which a series of translatory waves of perceptible magnitude develops and moves rapidly downstream. Pulsating flow is a matter of concern in the design and operation of steep-gradient channels. If it should occur at high stages in a channel designed for stable flow, the capacity of the channel may be inadequate at a discharge that is much smaller than that for which the channel was designed. If the overriding translatory wave carries an appreciable part of the total flow, conventional stream-gaging procedures cannot be used to determine the discharge; neither the conventional instrumentation nor conventional methodology is adequate. A method of determining the discharge during pulsating flow was tested in the Santa Anita Wash flood control channel in Arcadia, Calif., April 16, 1965. Observations of the dimensions and velocities of translatory waves were made during a period of controlled reservoir releases of about 100, 200, and 300 cfs (cubic feet per second). The method of computing discharge was based on (1) computation of the discharge in the overriding waves and (2) computation of the discharge in the shallow-depth, or overrun, part of the flow. Satisfactory results were obtained by this method. However, the procedure used-separating the flow into two components and then treating the shallow-depth component as though it were steady--has no theoretical basis. It is simply an expedient for use until laboratory investigation can provide a satisfactory analytical solution to the problem of computing discharge during pulsating flow. Sixteen months prior to the test in Santa Anita Wash, a robot camera had been designed .and programmed to obtain the data needed to compute discharge by the method described above. The photographic equipment had been installed in Haines Creek flood control channel in Los Angeles, Calif., but it had not been completely tested because of the infrequency of

  10. Immunoregulatory effects of Taishan Pinus massoniana pollen polysaccharide on chicks co-infected with avian leukosis virus and Bordetella avium early in ovo.

    Science.gov (United States)

    Guo, Fanxia; Xue, Cong; Wu, Cun; Zhao, Xue; Qu, Tinghe; He, Xiaohua; Guo, Zhongkun; Zhu, Ruiliang

    2014-04-01

    In recent years, co-infection of chicken embryos with immunosuppressive viruses and bacteria occurs with an annually increasing frequency. Consequently, studies on new and safe immunoregulators, especially plant polysaccharides, have become a popular topic in the poultry industry. In the present study, we selected 300 specific pathogen free embryonated eggs, which were injected with subgroup B avian leukosis virus (ALV-B) and Bordetella avium (B. avium) to establish an artificial co-infection model. The chicks that hatched from these co-infected embryonated eggs were treated with Taishan Pinus massoniana pollen polysaccharide (TPPPS). Results indicated that relevant indices in the co-infection group were significantly lower than that in B. avium-only group. Furthermore, pathogenicity of B. avium was exacerbated, with the chicks exhibiting decreased body weights. The TPPPS groups exhibited gradual improvements in immune function and developmental status. Therefore, in terms of improving immunologic function and production performance, TPPPS could be used as immunoregulator for immune responses.

  11. Effects of feeding processed kidney bean meal (Phaseolus vulgaris by replacing soybean meal on egg fertility and qualities of chicks of white leghorn hens

    Directory of Open Access Journals (Sweden)

    Sisay Fikru

    2015-06-01

    Full Text Available A study was conducted to evaluate the effects of feeding processed kidney bean meal (PKBM by replacing soybean meal (SBM on fertility, hatchability, embryonic mortality and chick quality of white leghorn (WL hens. A total of 225 white leghorn hens (195 layers and 30 cocks with uniform body weight (BW and age were randomly distributed into 15 pens and assigned to five treatments (i.e., T1, T2, T3, T4, and T5. A total of 360 eggs collected from all the treatment birds were used for the analysis. The feeds of the treatments were SBM substituted by PKBM at 0, 25, 50, 75 and 100% levels for T1, T2, T3, T4, and T5, respectively. Replacement of SBM with PKBM in the diet did not affect the fertility, hatchability, embryonic mortality, chick length, chick weight, and chick quality by visual score. As no difference is observed, 100% replacement of SBM by PKBM (dosed at 100 g/kg concentrate diet is possible.

  12. Embryonic origin and fate of chondroid tissue and secondary cartilages in the avian skull

    OpenAIRE

    Lengelé, Benoît; Schowing, J.; Dhem, Antoine

    1996-01-01

    BACKGROUND: Chondroid tissue is an intermediate calcified tissue, mainly involved in desmocranial morphogenesis. Often associated with secondary cartilages, it remained of unprecise embryonic origin. METHODS: The latter was studied by performing isotopic isochronic grafts of quail encephalon onto 30 chick embryos. The so-obtained chimeras were sacrificed at the 9th, 12th, and 14th day of incubation. The contribution of graft- and host-derived cells to the histogenesis of chondroid tissue,...

  13. Effects of pulsation rate and viscosity on pulsation-induced taste enhancement: new insights into texture-taste interactions.

    Science.gov (United States)

    Burseg, Kerstin Martha Mensien; Camacho, Sara; Bult, Johannes Hendrikus Franciscus

    2011-05-25

    Oral stimulation with high-tastant concentrations that are alternared with low-tastant concentrations or water rinses (pulsatile stimulation) results in taste intensity ratings that are higher than continuous stimulation with the same average tastant concentration. This study tested the combined effects of taste pulsation rate and viscosity on pulsation-induced taste enhancement in apple juice. According to a tastant-kinetics hypothesis, less pulsation-induced taste enhancement is expected at enhanced pulsation rates in the high-viscous proximal stimulus compared to lower viscous stimuli. High-concentration sucrose apple juice pulses and low-concentration sucrose apple juice intervals were alternated at different pulsation periods (pulse + interval in seconds) every 2.5 s (period length = 5 s) or every 1.25 s (period length = 2.5 s). Pulsed stimuli were presented at two viscosity levels by the addition of pectin (0 and 10 g/L). Sweetness intensities of pulsed stimuli were compared to a continuous reference of the same net but nonalternating sucrose concentration. Sweetness ratings were higher for pulsatile stimuli than for continuous stimuli. In low-viscous stimuli, enhancement depended on the pulsation period and peaked at 5 s periods. In high-viscous stimuli, the same enhancement was observed for both pulsation periods. These results contradict a tastant-kinetics hypothesis of viscosity-induced taste suppression because impaired tastant kinetics by viscosity would predict the opposite: lower pulsation-induced taste enhancement for viscous stimuli, especially at higher pulsation rates. Instead, these observations favor an explanation based on perceptual texture-taste interactions, which predict the observed independence between viscosity and pulsation rate.

  14. Chick Noir”: Shopaholic Meets Double Indemnity

    Directory of Open Access Journals (Sweden)

    Kennedy Victoria

    2017-06-01

    Full Text Available In early 2014, several articles appeared proclaiming the rise to prominence of a new subgenre of the crime novel: “chick noir,” which included popular books like Gone Girl, The Silent Wife, and Before We Met. However, there was also resistance to the new genre label from critics who viewed it as belittling to women’s writing and to female-focused narratives. Indeed, the separation of female-centred books - whether “chick lit” or “chick noir” - from mainstream fiction remains highly problematic and reflects the persistence of a gendered literary hierarchy. However, as this paper suggests, the label “chick noir” also reflects the fact that in these novels the crime thriller has been revitalized through cross-pollination with the so-called chick lit novel. I contend that chick lit and chick noir are two narrative forms addressing many of the same concerns relating to the modern woman, offering two different responses: humour and horror. Comparing the features of chick noir to those of chick lit and noir crime fiction, I suggest that chick noir may be read as a manifestation of feminist anger and anxiety - responses to the contemporary pressure to be “wonder women.”

  15. Pulsating hydraulic fracturing technology in low permeability coal seams

    Institute of Scientific and Technical Information of China (English)

    Wang Wenchao; Li Xianzhong; Lin Baiquan; Zhai Cheng

    2015-01-01

    Based on the difficult situation of gas drainage in a single coal bed of high gas content and low perme-ability, we investigate the technology of pulsating hydraulic pressure relief, the process of crank plunger movement and the mechanism of pulsating pressure formation using theoretical research, mathematical modeling and field testing. We analyze the effect of pulsating pressure on the formation and growth of fractures in coal by using the pulsating hydraulic theory in hydraulics. The research results show that the amplitude of fluctuating pressure tends to increase in the case where the exit is blocked, caused by pulsating pressure reflection and frictional resistance superposition, and it contributes to the growth of fractures in coal. The crack initiation pressure of pulsating hydraulic fracturing is 8 MPa, which is half than that of normal hydraulic fracturing;the pulsating hydraulic fracturing influence radius reaches 8 m. The total amount of gas extraction is increased by 3.6 times, and reaches 50 L/min at the highest point. The extraction flow increases greatly, and is 4 times larger than that of drilling without fracturing and 1.2 times larger than that of normal hydraulic fracturing. The technology provides a technical measure for gas drainage of high gas content and low permeability in the single coal bed.

  16. Sher 25: pulsating but apparently alone

    CERN Document Server

    Taylor, William D; Simón-Díaz, Sergio; Sana, Hugues; Langer, Norbert; Smith, Nathan; Smartt, Stephen J

    2014-01-01

    The blue supergiant Sher25 is surrounded by an asymmetric, hourglass-shaped circumstellar nebula, which shows similarities to the triple-ring structure seen around SN1987A. From optical spectroscopy over six consecutive nights, we detect periodic radial velocity variations in the stellar spectrum of Sher25 with a peak-to-peak amplitude of ~12 km/s on a timescale of about 6 days, confirming the tentative detec-tion of similar variations by Hendry et al. From consideration of the amplitude and timescale of the signal, coupled with observed line profile variations, we propose that the physical origin of these variations is related to pulsations in the stellar atmosphere, rejecting the previous hypothesis of a massive, short-period binary companion. The radial velocities of two other blue supergiants with similar bipolar nebulae, SBW1 and HD 168625, were also monitored over the course of six nights, but these did not display any significant radial velocity variations.

  17. Is $\\lambda$ Cep a pulsating star?

    CERN Document Server

    Uuh-Sonda, J M; Rauw, G

    2014-01-01

    It has been proposed that the variability seen in absorption lines of the O6Ief star $\\lambda$ Cep is periodical and due to non-radial pulsations (NRP). We have obtained new spectra during six campaigns lasting between five and nine nights. In some datasets we find recurrent spectral variations which move redward in the absorption line profile, consistent with perturbations on the stellar surface of a rotating star. However the periods found are not stable between datasets, at odds with the NRP hypothesis. Moreover, even when no redward trend is found in a full dataset of an observing campaign, it can be present in a subset, suggesting that the phenomenon is short-lived, of the order of a few days, and possibly linked to transient magnetic loops.

  18. Pc3 pulsations during variable IMF conditions

    Directory of Open Access Journals (Sweden)

    U. Villante

    Full Text Available Pc3 geomagnetic field fluctuations detected at low latitude (L'Aquila, Italy during the passage of a high velocity solar wind stream, characterized by variable interplanetary magnetic field conditions, are analyzed. Higher frequency resonant fluctuations and lower frequency phenomena are simultaneously observed; the intermittent appearance and the variable frequency of the longer period modes can be well interpreted in terms of the variable IMF elements; moreover their polarization characteristics are consistent with an origin related to external waves propagating in antisunward direction. A comparison with simultaneous observations performed at Terra Nova Bay (Antarctica provides additional evidence for a clear relationship between the IMF and Pc3 pulsations also at very high latitudes.

    Key words. Magnetospheric physics (MHD waves and instabilities; solar wind · magnetosphere interactions

  19. Pulsating stars in SuperWASP

    Directory of Open Access Journals (Sweden)

    Holdsworth Daniel L.

    2017-01-01

    Full Text Available SuperWASP is one of the largest ground-based surveys for transiting exoplanets. To date, it has observed over 31 million stars. Such an extensive database of time resolved photometry holds the potential for extensive searches of stellar variability, and provide solid candidates for the upcoming TESS mission. Previous work by e.g. [15], [5], [12] has shown that the WASP archive provides a wealth of pulsationally variable stars. In this talk I will provide an overview of the SuperWASP project, present some of the published results from the survey, and some of the on-going work to identify key targets for the TESS mission.

  20. THE PULSATION MODE OF THE CEPHEID POLARIS

    Energy Technology Data Exchange (ETDEWEB)

    Turner, D. G. [Department of Astronomy and Physics, Saint Mary' s University, Halifax NS B3H 3C3 (Canada); Kovtyukh, V. V.; Usenko, I. A. [Astronomical Observatory, Odessa National University, and Isaac Newton Institute of Chile, Odessa Branch, T. G. Shevkenko Park, 65014 Odessa (Ukraine); Gorlova, N. I., E-mail: turner@ap.smu.ca [Institute of Astronomy, Celestijnenlaan 200D, B-3001 Leuven (Belgium)

    2013-01-01

    A previously derived photometric parallax of 10.10 {+-} 0.20 mas, d = 99 {+-} 2 pc, is confirmed for Polaris by a spectroscopic parallax derived using line ratios in high dispersion spectra for the Cepheid. The resulting estimates for the mean luminosity of (M{sub V} ) = -3.07 {+-} 0.01 s.e., average effective temperature of (T{sub eff}) = 6025 {+-} 1 K s.e., and intrinsic color of ((B) - (V)){sub 0} = +0.56 {+-} 0.01 s.e., which match values obtained previously from the photometric parallax for a space reddening of E{sub B-V} = 0.02 {+-} 0.01, are consistent with fundamental mode pulsation for Polaris and a first crossing of the instability strip, as also argued by its rapid rate of period increase. The systematically smaller Hipparcos parallax for Polaris appears discrepant by comparison.

  1. Ambiguity of mapping the relative phase of blood pulsations

    Science.gov (United States)

    Teplov, Victor; Nippolainen, Ervin; Makarenko, Alexander A.; Giniatullin, Rashid; Kamshilin, Alexei A.

    2014-01-01

    Blood pulsation imaging (BPI) is a non-invasive optical method based on photoplethysmography (PPG). It is used for the visualization of changes in the spatial distribution of blood in the microvascular bed. BPI specifically allows measurements of the relative phase of blood pulsations and using it we detected a novel type of PPG fast waveforms, which were observable in limited areas with asynchronous regional blood supply. In all subjects studied, these fast waveforms coexisted with traditional slow waveforms of PPG. We are therefore presenting a novel lock-in image processing technique of blood pulsation imaging, which can be used for detailed temporal characterization of peripheral microcirculation. PMID:25401026

  2. Ambiguity of mapping the relative phase of blood pulsations.

    Science.gov (United States)

    Teplov, Victor; Nippolainen, Ervin; Makarenko, Alexander A; Giniatullin, Rashid; Kamshilin, Alexei A

    2014-09-01

    Blood pulsation imaging (BPI) is a non-invasive optical method based on photoplethysmography (PPG). It is used for the visualization of changes in the spatial distribution of blood in the microvascular bed. BPI specifically allows measurements of the relative phase of blood pulsations and using it we detected a novel type of PPG fast waveforms, which were observable in limited areas with asynchronous regional blood supply. In all subjects studied, these fast waveforms coexisted with traditional slow waveforms of PPG. We are therefore presenting a novel lock-in image processing technique of blood pulsation imaging, which can be used for detailed temporal characterization of peripheral microcirculation.

  3. High-resolution in vivo imaging of the cross-sectional deformations of contracting embryonic heart loops using optical coherence tomography

    DEFF Research Database (Denmark)

    Männer, J.; Thrane, Lars; Norozi, K.

    2008-01-01

    tubes as concentric narrowing and widening of tubes of circular cross-section. We have visualized the cross-sectional deformations of contracting embryonic hearts in chick embryos (HH-stages 9-17) using real-time high-resolution optical coherence tomography. Cardiac contractions are detected from HH...

  4. Electroporation of the hindbrain to trace axonal trajectories and synaptic targets in the chick embryo.

    Science.gov (United States)

    Kohl, Ayelet; Hadas, Yoav; Klar, Avihu; Sela-Donenfeld, Dalit

    2013-05-29

    Electroporation of the chick embryonic neural tube has many advantages such as being quick and efficient for the expression of foreign genes into neuronal cells. In this manuscript we provide a method that demonstrates uniquely how to electroporate DNA into the avian hindbrain at E2.75 in order to specifically label a subset of neuronal progenitors, and how to follow their axonal projections and synaptic targets at much advanced stages of development, up to E14.5. We have utilized novel genetic tools including specific enhancer elements, Cre/Lox - based plasmids and the PiggyBac-mediated DNA transposition system to drive GFP expression in a subtype of hindbrain cells (the dorsal most subgroup of interneurons, dA1). Axonal trajectories and targets of dA1 axons are followed at early and late embryonic stages at various brainstem regions. This strategy contributes advanced techniques for targeting cells of interest in the embryonic hindbrain and for tracing circuit formation at multiple stages of development.

  5. Report of geomagnetic pulsation indices for space weather applications

    Science.gov (United States)

    Xu, Z.; Gannon, Jennifer L.; Rigler, Erin J.

    2013-01-01

    The phenomenon of ultra-low frequency geomagnetic pulsations was first observed in the ground-based measurements of the 1859 Carrington Event and has been studied for over 100 years. Pulsation frequency is considered to be “ultra” low when it is lower than the natural frequencies of the plasma, such as the ion gyrofrequency. Ultra-low frequency pulsations are considered a source of noise in some geophysical analysis techniques, such as aeromagnetic surveys and transient electromagnetics, so it is critical to develop near real-time space weather products to monitor these geomagnetic pulsations. The proper spectral analysis of magnetometer data, such as using wavelet analysis techniques, can also be important to Geomagnetically Induced Current risk assessment.

  6. Search of Secondary Pulsation Modes: Globular cluster (NGC 6496)

    CERN Document Server

    Joshi, Gireesh C

    2016-01-01

    The Fourier-discrete-peridogram are used to identify pulsation modes in variables. We have found two pulsation modes in V1 and V2 among 13 new variables as described by Abbas et al.. The five variables V9 to V13 are not shown close to periodic values by analysis of the frequency distribution of multi-band data and also create difficulty to describe their varied nature. The multi-band periodic values of V1 and V6 are matched with known literature values. The scattering of the varied nature of secondary pulsation modes is eliminated by moving average methodology. The phase curve of secondary mode is found to be more smooth compared to a prominent mode of pulsation.

  7. Unilateral Loss of Spontaneous Venous Pulsations in an Astronaut

    Science.gov (United States)

    Mader, Thomas H.; Gibson, C. Robert; Lee, Andrew G.; Patel, Nimesh; Hart, Steven; Pettit, Donald R.

    2014-01-01

    Spontaneous venous pulsations seen on the optic nerve head (optic disc) are presumed to be caused by fluctuations in the pressure gradient between the intraocular and retrolaminar venous systems. The disappearance of previously documented spontaneous venous pulsations is a well-recognized clinical sign usually associated with a rise in intracranial pressure and a concomitant bilateral elevation of pressure in the subarachnoid space surrounding the optic nerves. In this correspondence we report the unilateral loss of spontaneous venous pulsations in an astronaut 5 months into a long duration space flight. We documented a normal lumbar puncture opening pressure 8 days post mission. The spontaneous venous pulsations were also documented to be absent 21 months following return to Earth.. We hypothesize that these changes may have resulted from a chronic unilateral rise in optic nerve sheath pressure caused by a microgravity-induced optic nerve sheath compartment syndrome.

  8. Stochastic Processes in Yellow and Red Pulsating Variables

    CERN Document Server

    Turner, David G; Colivas, T; Berdnikov, Leonid N; Abdel-Latif, Mohamed Abdel-Sabour

    2009-01-01

    Random changes in pulsation period are well established in cool pulsating stars, in particular the red giant variables: Miras, semi-regulars of types A and B, and RV Tau variables. Such effects are also observed in a handful of Cepheids, the SX Phe variable XX Cyg, and, most recently, the red supergiant variable, BC Cyg, a type C semi-regular. The nature of such fluctuations is seemingly random over a few pulsation cycles of the stars, yet the regularity of the primary pulsation mechanism dominates over the long term. The degree of stochasticity is linked to the dimensions of the stars, the randomness parameter 'e' appearing to correlate closely with mean stellar radius through the period 'P', with an average value of e/P = 0.0136+-0.0005. The physical processes responsible for such fluctuations are uncertain, but presumably originate in temporal modifications of envelope convection in such stars.

  9. LARGE EDDY SIMULATION OF PULSATING TURBULENT OPEN CHANNEL FLOW

    Institute of Scientific and Technical Information of China (English)

    ZOU Li-yong; LIU Nan-sheng; LU Xi-yun

    2004-01-01

    Pulsating turbulent open channel flow has been investigated by the use of Large Eddy Simulation (LES) technique coupled with dynamic Sub-Grid-Scale (SGS) model for turbulent SGS stress to closure the governing equations. Three-dimensional filtered Navier-Stokes equations are numerically solved by a fractional-step method. The objective of this study is to deal with the behavior of the pulsating turbulent open channel flow and to examine the reliability of the LES approach for predicting the pulsating turbulent flow. In this study, the Reynolds number (Reτ ) is chosen as 180 based on the friction velocity and the channel depth. The frequency of the driving pressure gradient for the pulsating turbulent flow ranges low, medium and high value. Statistical turbulence quantities as well as the flow structures are analyzed.

  10. Return of Pulsations in SDSS 0745+4538

    Science.gov (United States)

    Mukadam, Anjum S.; Townsley, D. M.; Szkody, P.; Gänsicke, B. T.; Winget, D. E.; Hermes, J. J.; Howell, Steve B.; Teske, J.; Patterson, Joseph; Kemp, Jonathan; Armstrong, Eve

    2010-11-01

    Nonradial pulsations had ceased in the accreting white dwarf SDSS J074531.92+453829.6 subsequent to its October 2006 outburst. We recently acquired optical high-speed time-series photometry on this cataclysmic variable more than three years after its outburst to find that pulsations have now returned to the primary white dwarf. Moreover, the observed pulsation periods agree with pre-outburst periods within the uncertainties of 1-2 s. This discovery is both remarkable and significant because it indicates that the outburst did not affect the interior stellar structure, which dictates the observed pulsation frequencies. Using this discovery in addition to an HST ultra-violet temperature measurement obtained one year after outburst, we have also been able to constrain the matter accreted during the 2006 outburst.

  11. Micro-Channel Embedded Pulsating Heat Pipes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As the need for thermal control technology becomes more demanding Micro-Channel Embedded Pulsating Heat Pipes (ME-PHPs) represents a sophisticated and enabling...

  12. Oxygenated drinking water enhances immune activity in broiler chicks and increases survivability against Salmonella Gallinarum in experimentally infected broiler chicks.

    Science.gov (United States)

    Jung, Bock-Gie; Lee, Jin-A; Nam, Kyoung-Woo; Lee, Bong-Joo

    2012-03-01

    It has been suggested that drinking oxygenated water may improve oxygen availability, which may increase vitality and improving immune activity. The present study evaluated the immune enhancing effects of oxygenated drinking water in broiler chicks and demonstrated the protective efficacy of oxygenated drinking water against Salmonella Gallinarum in experimentally infected broiler chicks. Continuous drinking of oxygenated water markedly increased serum lysozyme activity, peripheral blood mononuclear cell proliferation and the CD4(+)/CD8(+) splenocyte ratio in broiler chicks. In the chicks experimentally infected with S. Gallinarum, oxygenated drinking water alleviated symptoms and increased survival. These findings suggest that oxygenated drinking water enhances immune activity in broiler chicks, and increases survivability against S. Gallinarum in experimentally infected broiler chicks.

  13. Nonradial Pulsations in Classical Cepheids of the Magellanic Clouds

    CERN Document Server

    Moskalik, P; Moskalik, Pawel; Mizerski, Zbigniew Kolaczkowski & Tomasz

    2003-01-01

    We have performed systematic frequency analysis of the LMC Cepheids observed by OGLE project. Several new types of pulsation behaviour are identified, including triple-mode and amplitude-modulated double-mode pulsations. In ~10% of the first overtone Cepheids we find low amplitude secondary periodicities corresponding to nonradial modes. This is the first evidence for excitation of nonradial oscillations in Classical Cepheid variables.

  14. 3D Convection-pulsation Simulations with the HERACLES Code

    Science.gov (United States)

    Felix, S.; Audit, E.; Dintrans, B.

    2015-10-01

    We present 3D simulations of the coupling between surface convection and pulsations due to the κ-mechanism in classical Cepheids of the red edge of Hertzsprung-Russell diagram's instability strip. We show that 3D convection is less powerful than 2D convection and does not quench the radiative pulsations, leading to an efficient 3D κ-mechanism. Thus, the 3D instability strip is closer to the observed one than the 1D or 2D were.

  15. Self-Pulsating Semiconductor Lasers Theory and Experiment

    CERN Document Server

    Mirasso, C R; Hernández-García, E; Lenstra, D; Lynch, S; Landais, P; Phelan, P; O'Gorman, J; San Miguel, M; Elsasser, W

    1999-01-01

    We report detailed measurements of the pump-current dependency of the self-pulsating frequency of semiconductor CD lasers. A distinct kink in this dependence is found and explained using rate-equation model. The kink denotes a transition between a region where the self-pulsations are weakly sustained relaxation oscillations and a region where Q-switching takes place. Simulations show that spontaneous emission noise plays a crucial role for the cross-over.

  16. Developmental Stage-Specific Embryonic Induction of HepG2 Cell Differentiation.

    Science.gov (United States)

    Li, Yanning; Zong, Yanhong; Xiao, Zhigang; Zhu, Mengxuan; Xiao, Hui; Qi, Jinsheng; Liu, Kun; Wang, Hui

    2016-04-01

    Although hepatocellular carcinoma cells can sometimes undergo differentiation in an embryonic microenvironment, the mechanism is poorly understood. The developmental stage-specific embryonic induction of tumor cell differentiation was investigated. Both chick and mouse liver extracts and hepatoblast-enriched cells at different developmental stages were used to treat human hepatoma HepG2 cells, and the effects on the induction of differentiation were evaluated. The nuclear factors controlling differentiation, hepatocyte nuclear factor (HNF)-4α, HNF-1α, HNF-6 and upstream stimulatory factor-1 (USF-1), and the oncogene Myc and alpha-fetoprotein (AFP) were measured. HNF-4α RNA interference was used to verify the role of HNF-4α. Embryonic induction effects were further tested in vivo by injecting HepG2 tumor cells into immunodeficient nude mice. The 9-11-days chick liver extracts and 13.5-14.5-days mouse hepatoblast-enriched cells could inhibit proliferation and induce differentiation of HepG2 cells, leading to either death or maturation to hepatocytes. The maturation of surviving HepG2 cells was confirmed by increases in the expressions of HNF-4α, HNF-1α, HNF-6, and USF-1, and decreases in Myc and AFP. The embryonic induction of HepG2 cell maturation could be attenuated by HNF-4α RNA interference. Furthermore, the 13.5-days mouse hepatoblast culture completely eliminated HepG2 tumors with inhibited Myc and induced HNF-4α, confirming this embryonic induction effect in vivo. This study demonstrated that developmental stage-specific embryonic induction of HepG2 cell differentiation might help in understanding embryonic differentiation and oncogenesis.

  17. First Kepler results on compact pulsators - II. KIC 010139564, a new pulsating subdwarf B (V361 Hya) star with an additional low-frequency mode

    DEFF Research Database (Denmark)

    Kawaler, Stephen; Reed, M.D.; Quint, A.C.;

    2010-01-01

    We present the discovery of non-radial pulsations in a hot subdwarf B star based on 30.5 d of nearly continuous time series photometry using the Kepler spacecraft. KIC 010139564 is found to be a short-period pulsator of the V361 Hya (EC 14026) class with more than 10 independent pulsation modes...

  18. Efficacy of early chick nutrition with Aloe vera and Azadirachta indica on gut health and histomorphometry in chicks

    Science.gov (United States)

    Sujatha, Tamilvanan; Abhinaya, Sivasankar; Sunder, Jai; Thangapandian, Marudhai; Kundu, Anandamoy

    2017-01-01

    Aim: This study was conducted with an aim of studying the efficacy of water supplements of Aloe vera and Azadirachta indica (neem) during pre-starter age (0-2 weeks) on gut health and histomorphometry in Vanaraja chicks. Materials and Methods: A total of 192 day old Vanaraja chicks were randomly assigned to one of four herbal water treatments throughout the experimental pre-starter stage (0-2 weeks) in a completely randomized design. Each treatment was given four replicates consisting of 12 chicks per replicate. Water treatments comprised T1: Control with regular antibiotic supplement, T2: 3 ml Aloe juice per chick per day, T3: 3 ml neem extract per chick per day, T4: 1.5 ml Aloe and 1.5 ml neem per chick per day. Gut culture was done for Escherichia coli and Lactobacillus sps. and gut histomorphometry in 24 gut samples at 14 days of age. Results: This study revealed that supplementation of A. vera and neem in water significantly (pneem supplementation as compared to that of control chicks. Significantly lower crypt depth (pneem and Aloe supplementation in chicks as compared to their combination and control. Conclusion: Immediate post hatch supplementation of Aloe juice and neem extract in chicks improved the development and health of their gut. PMID:28717305

  19. Morphologic characterization of osteosarcoma growth on the chick chorioallantoic membrane

    Directory of Open Access Journals (Sweden)

    Gosheger Georg

    2010-03-01

    Full Text Available Abstract Background The chick chorio-allantoic membrane (CAM assay is a commonly used method for studying angiogenic or anti-angiogenic activities in vivo. The ease of access allows direct monitoring of tumour growth by biomicroscopy and the possibility to screen many samples in an inexpensive way. The CAM model provides a powerful tool to study effects of molecules, which interfere with physiological angiogenesis, or experimental tumours derived from cancer cell lines. We therefore screened eight osteosarcoma cell lines for their ability to form vascularized tumours on the CAM. Findings We implanted 3-5 million cells of human osteosarcoma lines (HOS, MG63, MNNG-HOS, OST, SAOS, SJSA1, U2OS, ZK58 on the CAM at day 10 of embryonic development. Tumour growth was monitored by in vivo biomicroscopy at different time points and tumours were fixed in paraformaldehyde seven days after cell grafting. The tissue was observed, photographed and selected cases were further analyzed using standard histology. From the eight cell lines the MNNG-HOS, U2OS and SAOS were able to form solid tumours when grafted on the CAM. The MNNG-HOS tumours showed the most reliable and consistent growth and were able to penetrate the chorionic epithelium, grow in the CAM stroma and induce a strong angiogenic response. Conclusions Our results show that the CAM assay is a useful tool for studying osteosarcoma growth. The model provides an excellent alternative to current rodent models and could serve as a preclinical screening assay for anticancer molecules. It might increase the speed and efficacy of the development of new drugs for the treatment of osteosarcoma.

  20. Chick embryos have the same pattern of hypoxic lower-brain activation as fetal mammals.

    Science.gov (United States)

    Landry, Jeremy P; Hawkins, Connor; Lee, Aaron; Coté, Alexandra; Balaban, Evan; Pompeiano, Maria

    2016-01-01

    cFos expression (indicating a particular kind of neuronal activation) was examined in embryonic day (E) 18 chick embryos after exposure to 4 h of either normoxia (21% O2), modest hypoxia (15% O2), or medium hypoxia (10% O2). Eight regions of the brainstem and hypothalamus were surveyed, including seven previously shown to respond to hypoxia in late-gestation mammalian fetuses (Breen et al., 1997; Nitsos and Walker, 1999b). Hypoxia-related changes in chick embryo brain activation mirrored those found in fetal mammals with the exception of the medullary Raphe, which showed decreased hypoxic activation, compared with no change in mammals. This difference may be explained by the greater anapyrexic responses of chick embryos relative to mammalian fetuses. Activation in the A1/C1 region was examined in more detail to ascertain whether an O2-sensitive subpopulation of these cells containing heme oxygenase 2 (HMOX2) may drive hypoxic brain responses before the maturation of peripheral O2-sensing. HMOX2-positive and -negative catecholaminergic cells and interdigitating noncatecholaminergic HMOX2-positive cells all showed significant changes in cFos expression to hypoxia, with larger population responses seen in the catecholaminergic cells. Hypoxia-induced activation of lower-brain regions studied here was significantly better correlated with activation of the nucleus of the solitary tract (NTS) than with that of HMOX2-containing A1/C1 neurons. Together, these observations suggest that (1) the functional circuitry controlling prenatal brain responses to hypoxia is strongly conserved between birds and mammals, and (2) NTS neurons are a more dominant driving force for prenatal hypoxic cFos brain responses than O2-sensing A1/C1 neurons.

  1. First Kepler results on compact pulsators - III. Subdwarf B stars with V1093 Her and hybrid (DW Lyn) type pulsations

    DEFF Research Database (Denmark)

    Reed, M.D.; Kawaler, Stephen D.; Østensen, Roy H.

    2010-01-01

    1093 Her (PG 1716) class or a hybrid star with both short and long periods. The apparently non-binary long-period and hybrid pulsators are described here. The V1093 Her periods range from 1 to 4.5 h and are associated with g-mode pulsations. Three stars also exhibit short periods indicative of p......We present the discovery of non-radial pulsations in five hot subdwarf B (sdB) stars based on 27 d of nearly continuous time series photometry using the Kepler spacecraft. We find that every sdB star cooler than ≈27 500 K that Kepler has observed (seven so far) is a long-period pulsator of the V......-modes with periods of 2-5 min and in addition, these stars exhibit periodicities between both classes from 15 to 45 min. We detect the coolest and longest-period V1093 Her-type pulsator to date, KIC010670103 (Teff≈ 20 900 K, Pmax≈ 4.5 h) as well as a suspected hybrid pulsator, KIC002697388, which is extremely cool...

  2. SABRE observations of Pi2 pulsations: case studies

    Science.gov (United States)

    Bradshaw, E. G.; Lester, M.

    1997-01-01

    The characteristics of substorm-associated Pi2 pulsations observed by the SABRE coherent radar system during three separate case studies are presented. The SABRE field of view is well positioned to observe the differences between the auroral zone pulsation signature and that observed at mid-latitudes. During the first case study the SABRE field of view is initially in the eastward electrojet, equatorward and to the west of the substorm-enhanced electrojet current. As the interval progresses, the western, upward field-aligned current of the substorm current wedge moves westward across the longitudes of the radar field of view. The westward motion of the wedge is apparent in the spatial and temporal signatures of the associated Pi2 pulsation spectra and polarisation sense. During the second case study, the complex field-aligned and ionospheric currents associated with the pulsation generation region move equatorward into the SABRE field of view and then poleward out of it again after the third pulsation in the series. The spectral content of the four pulsations during the interval indicate different auroral zone and mid-latitude signatures. The final case study is from a period of low magnetic activity when SABRE observes a Pi2 pulsation signature from regions equatorward of the enhanced substorm currents. There is an apparent mode change between the signature observed by SABRE in the ionosphere and that on the ground by magnetometers at latitudes slightly equatorward of the radar field of view. The observations are discussed in terms of published theories of the generation mechanisms for this type of pulsation. Different signatures are observed by SABRE depending on the level of magnetic activity and the position of the SABRE field of view relative to the pulsation generation region. A twin source model for Pi2 pulsation generation provides the clearest explanation of the signatures observed Acknowledgements. The authors are grateful to Prof. D. J. Southwood

  3. NMR Based Cerebrum Metabonomic Analysis Reveals Simultaneous Interconnected Changes during Chick Embryo Incubation.

    Science.gov (United States)

    Feng, Yue; Zhu, Hang; Zhang, Xu; Wang, Xuxia; Xu, Fuqiang; Tang, Huiru; Ye, Chaohui; Liu, Maili

    2015-01-01

    To find out if content changes of the major functional cerebrum metabolites are interconnected and formed a network during the brain development, we obtained high-resolution magic-angle-spinning (HR-MAS) 1H NMR spectra of cerebrum tissues of chick embryo aged from incubation day 10 to 20, and postnatal day 1, and analyzed the data with principal component analysis (PCA). Within the examined time window, 26 biological important molecules were identified and 12 of them changed their relative concentration significantly in a time-dependent manner. These metabolites are generally belonged to three categories, neurotransmitters, nutrition sources, and neuronal or glial markers. The relative concentration changes of the metabolites were interconnected among/between the categories, and, more interestingly, associated with the number and size of Nissl-positive neurons. These results provided valuable biochemical and neurochemical information to understand the development of the embryonic brain.

  4. Source of temperature and pressure pulsations during sessile droplet evaporation into multicomponent atmospheres.

    Science.gov (United States)

    Persad, Aaron H; Sefiane, Khellil; Ward, Charles A

    2013-10-29

    During sessile droplet evaporation, studies with IR thermography and shadowgraphs have indicated temperature pulsations. We confirm those observations with microthermocouples, but microthermocouples also indicate temperature pulsations in the atmosphere of the droplet. The pressure in this atmosphere pulsated as well and was correlated with the temperature pulsations in the droplet. Also, we find that if a droplet evaporates into its own vapor, there are no temperature or pressure pulsations. The pulsations occur only if the droplet evaporates into an atmosphere with a component having a heat of solution with the droplet when it adsorbs-absorbs. None of the currently proposed mechanisms for the temperature pulsations provide an explanation for the coupling between the temperature pulsations in the droplet and the vapor-phase pressure pulsations, and for the absence of the pulsations when the system is single-component. As a mechanism for the pulsations, we propose that when a droplet is exposed to an atmosphere containing a component that has a heat of solution with the droplet, energy will be released from adsorption-absorption. This energy will cause pulsations in the evaporation flux, and these pulsations could cause the observed temperature and pressure pulsations. We examine this mechanism by showing that, if the measured temperature pulsations in a water droplet exposed to a methanol atmosphere are used as the input to a theory of evaporation kinetics (statistical rate theory), the pressure pulsations of the water vapor in the methanol atmosphere are predicted and agree with those measured with a quadrupole mass analyzer. When the inputs and outputs are reversed in the theory, we find that the temperature pulsations in the droplet are correctly predicted from the measured water vapor pulsations in the atmosphere.

  5. Radio Pulsating Structures with Coronal Loop Contraction

    Science.gov (United States)

    Kallunki, J.; Pohjolainen, S.

    2012-10-01

    We present a multi-wavelength study of a solar eruption event on 20 July 2004, comprising observations in Hα, EUV, soft X-rays, and in radio waves with a wide frequency range. The analyzed data show both oscillatory patterns and shock wave signatures during the impulsive phase of the flare. At the same time, large-scale EUV loops located above the active region were observed to contract. Quasi-periodic pulsations with ˜ 10 and ˜ 15 s oscillation periods were detected both in microwave - millimeter waves and in decimeter - meter waves. Our calculations show that MHD oscillations in the large EUV loops - but not likely in the largest contracting loops - could have produced the observed periodicity in radio emission, by triggering periodic magnetic reconnection and accelerating particles. As the plasma emission in decimeter - meter waves traces the accelerated particle beams and the microwave emission shows a typical gyrosynchrotron flux spectrum (emission created by trapped electrons within the flare loop), we find that the particles responsible for the two different types of emission could have been accelerated in the same process. Radio imaging of the pulsed decimetric - metric emission and the shock-generated radio type II burst in the same wavelength range suggest a rather complex scenario for the emission processes and locations. The observed locations cannot be explained by the standard model of flare loops with an erupting plasmoid located above them, driving a shock wave at the CME front.

  6. The evolved pulsating CEMP star HD112869

    CERN Document Server

    Začs, L; Grankina, A; Deveikis, V; Kaminskyi, B; Pavlenko, Y; Musaev, F

    2015-01-01

    Radial velocity measurements, $BVR_C$ photometry, and high-resolution spectroscopy in the wavelength region from blue to near infrared are employed in order to clarify the evolutionary status of the carbon-enhanced metal-poor star HD112869 with unique ratio of carbon isotopes in the atmosphere. An LTE abundance analysis was carried out using the method of spectral synthesis and new self consistent 1D atmospheric models. The radial velocity monitoring confirmed semiregular variations with a peak-to-peak amplitude of about 10 km $s^{-1}$ and a dominating period of about 115 days. The light, color and radial velocity variations are typical of the evolved pulsating stars. The atmosphere of HD112869 appears to be less metal-poor than reported before, [Fe/H] = -2.3 $\\pm$0.2 dex. Carbon to oxygen and carbon isotope ratios are found to be extremely high, C/O $\\simeq$ 12.6 and $^{12}C/^{13}C \\gtrsim$ 1500, respectively. The s-process elements yttrium and barium are not enhanced, but neodymium appears to be overabundan...

  7. FGF signaling pathway in the developing chick lung: expression and inhibition studies.

    Directory of Open Access Journals (Sweden)

    Rute S Moura

    Full Text Available BACKGROUND: Fibroblast growth factors (FGF are essential key players during embryonic development. Through their specific cognate receptors (FGFR they activate intracellular cascades, finely regulated by modulators such as Sprouty. Several FGF ligands (FGF1, 2, 7, 9, 10 and 18 signaling through the four known FGFRs, have been implicated in lung morphogenesis. Although much is known about mammalian lung, so far, the avian model has not been explored for lung studies. METHODOLOGY/PRINCIPAL FINDINGS: In this study we provide the first description of fgf10, fgfr1-4 and spry2 expression patterns in early stages of chick lung development by in situ hybridization and observe that they are expressed similarly to their mammalian counterparts. Furthermore, aiming to determine a role for FGF signaling in chick lung development, in vitro FGFR inhibition studies were performed. Lung explants treated with an FGF receptor antagonist (SU5402 presented an impairment of secondary branch formation after 48 h of culture; moreover, abnormal lung growth with a cystic appearance of secondary bronchi and reduction of the mesenchymal tissue was observed. Branching and morphometric analysis of lung explants confirmed that FGFR inhibition impaired branching morphogenesis and induced a significant reduction of the mesenchyme. CONCLUSIONS/SIGNIFICANCE: This work demonstrates that FGFRs are essential for the epithelial-mesenchymal interactions that determine epithelial branching and mesenchymal growth and validate the avian embryo as a good model for pulmonary studies, namely to explore the FGF pathway as a therapeutic target.

  8. Protein expression profiling during chick retinal maturation: a proteomics-based approach

    Directory of Open Access Journals (Sweden)

    Stitt Alan W

    2008-12-01

    Full Text Available Abstract Background The underlying pathways that drive retinal neurogenesis and synaptogenesis are still relatively poorly understood. Protein expression analysis can provide direct insight into these complex developmental processes. The aim of this study was therefore to employ proteomic analysis to study the developing chick retina throughout embryonic (E development commencing at day 12 through 13, 17, 19 and post-hatch (P 1 and 33 days. Results 2D proteomic and mass spectrometric analysis detected an average of 1514 spots per gel with 15 spots demonstrating either modulation or constitutive expression identified via MS. Proteins identified included alpha and beta-tubulin, alpha enolase, B-creatine kinase, gamma-actin, platelet-activating factor (PAF, PREDICTED: similar to TGF-beta interacting protein 1, capping protein (actin filament muscle Z line, nucleophosmin 1 (NPM1, dimethylarginine dimethylaminohydrolase, triosphoaphate isomerase, DJ1, stathmin, fatty acid binding protein 7 (FABP7/B-FABP, beta-synuclein and enhancer of rudimentary homologue. Conclusion This study builds upon previous proteomic investigations of retinal development and represents the addition of a unique data set to those previously reported. Based on reported bioactivity some of the identified proteins are most likely to be important to normal retinal development in the chick. Continued analysis of the dynamic protein populations present at the early stages and throughout retinal development will increase our understanding of the molecular events underpinning retinogenesis.

  9. Exposure to excess phenobarbital negatively influences the osteogenesis of chick embryos

    Directory of Open Access Journals (Sweden)

    Yu Yan

    2016-09-01

    Full Text Available Phenobarbital is an antiepileptic drug that is widely used to treat epilepsy in a clinical setting. However, a long term of phenobarbital administration in pregnant women may produce side effects on embryonic skeletogenesis. In this study, we aim to investigate the mechanism by which phenobarbital treatment induces developmental defects in long bones. We first determined that phenobarbital treatment decreased chondrogenesis and inhibited the proliferation of chondrocytes in chick embryos. Phenobarbital treatment also suppressed mineralization in both in vivo and in vitro long bone models. Next, we established that phenobarbital treatment delayed blood vessel invasion in a cartilage template, and this finding was supported by the down-regulation of vascular endothelial growth factor in the hypertrophic zone following phenobarbital treatment. Phenobarbital treatment inhibited tube formation and the migration of human umbilical vein endothelial cells. In addition, it impaired angiogenesis in chick yolk sac membrane model and chorioallantoic membrane model. In summary, phenobarbital exposure led to shortened lengths of long bones during embryogenesis, which might result from inhibiting mesenchyme differentiation, chondrocyte proliferation, and delaying mineralization by impairing vascular invasion.

  10. Characteristics of odorant elicited calcium fluxes in acutely-isolated chick olfactory neurons.

    Science.gov (United States)

    Jung, Yewah; Wirkus, Eric; Amendola, Diedra; Gomez, George

    2005-06-01

    To understand avian olfaction, it is important to characterize the peripheral olfactory system of a representative bird species. This study determined the functional properties of olfactory receptor neurons of the chicken olfactory epithelium. Individual neurons were acutely isolated from embryonic day-18 to newborn chicks by dissection and enzymatic dissociation. We tested single olfactory neurons with behaviorally relevant odorant mixtures and measured their responses using ratiometric calcium imaging; techniques used in this study were identical to those used in other studies of olfaction in other vertebrate species. Chick olfactory neurons displayed properties similar to those found in other vertebrates: they responded to odorant stimuli with either decreases or increases in intracellular calcium, calcium increases were mediated by a calcium influx, and responses were reversibly inhibited by 100 microM L: -cis-diltiazem, 1 mM Neomycin, and 20 microM U73122, which are biochemical inhibitors of second messenger signaling. In addition, some cells showed a complex pattern of responses, with different odorant mixtures eliciting increases or decreases in calcium in the same cell. It appears that there are common features of odorant signaling shared by a variety of vertebrate species, as well as features that may be peculiar to chickens.

  11. Comprehensive analysis of fibroblast growth factor receptor expression patterns during chick forelimb development.

    Science.gov (United States)

    Sheeba, Caroline J; Andrade, Raquel P; Duprez, Delphine; Palmeirim, Isabel

    2010-01-01

    Specific interactions between fibroblast growth factors (Fgf1-22) and their tyrosine kinase receptors (FgfR1-4) activate different signalling pathways that are responsible for the biological processes in which Fgf signalling is implicated during embryonic development. In the chick, several Fgf ligands (Fgf2, 4, 8, 9, 10, 12, 13 and 18) and the four FgfRs (FgfR 1, 2, 3 and 4) have been reported to be expressed in the developing limb. The precise spatial and temporal expression of these transcripts is important to guide the limb bud to develop into a wing/leg. In this paper, we present a detailed and systematic analysis of the expression patterns of FgfR1, 2, 3 and 4 throughout chick wing development, by in situ hybridisation on whole mounts and sections. Moreover, we characterize for the first time the different isoforms of FGFR1-3 by analysing their differential expression in limb ectoderm and mesodermal tissues, using RT-PCR and in situ hybridisation on sections. Finally, isoform-specific sequences for FgfR1IIIb, FgfR1IIIc, FgfR3IIIb and FgfR3IIIc were determined and deposited in GenBank with the following accession numbers: GU053725, GU065444, GU053726, GU065445, respectively.

  12. Rediscovering the chick embryo as a model to study retinal development

    Directory of Open Access Journals (Sweden)

    Vergara M Natalia

    2012-06-01

    Full Text Available Abstract The embryonic chick occupies a privileged place among animal models used in developmental studies. Its rapid development and accessibility for visualization and experimental manipulation are just some of the characteristics that have made it a vertebrate model of choice for more than two millennia. Until a few years ago, the inability to perform genetic manipulations constituted a major drawback of this system. However, the completion of the chicken genome project and the development of techniques to manipulate gene expression have allowed this classic animal model to enter the molecular age. Such techniques, combined with the embryological manipulations that this system is well known for, provide a unique toolkit to study the genetic basis of neural development. A major advantage of these approaches is that they permit targeted gene misexpression with extremely high spatiotemporal resolution and over a large range of developmental stages, allowing functional analysis at a level, speed and ease that is difficult to achieve in other systems. This article provides a general overview of the chick as a developmental model focusing more specifically on its application to the study of eye development. Special emphasis is given to the state of the art of the techniques that have made gene gain- and loss-of-function studies in this model a reality. In addition, we discuss some methodological considerations derived from our own experience that we believe will be beneficial to researchers working with this system.

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

    Science.gov (United States)

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

    2015-03-01

    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.

  14. Exposure to Excess Phenobarbital Negatively Influences the Osteogenesis of Chick Embryos

    Science.gov (United States)

    Yan, Yu; Cheng, Xin; Yang, Ren-Hao; Li, He; Chen, Jian-Long; Ma, Zheng-Lai; Wang, Guang; Chuai, Manli; Yang, Xuesong

    2016-01-01

    Phenobarbital is an antiepileptic drug that is widely used to treat epilepsy in a clinical setting. However, a long term of phenobarbital administration in pregnant women may produce side effects on embryonic skeletogenesis. In this study, we aim to investigate the mechanism by which phenobarbital treatment induces developmental defects in long bones. We first determined that phenobarbital treatment decreased chondrogenesis and inhibited the proliferation of chondrocytes in chick embryos. Phenobarbital treatment also suppressed mineralization in both in vivo and in vitro long bone models. Next, we established that phenobarbital treatment delayed blood vessel invasion in a cartilage template, and this finding was supported by the down-regulation of vascular endothelial growth factor in the hypertrophic zone following phenobarbital treatment. Phenobarbital treatment inhibited tube formation and the migration of human umbilical vein endothelial cells. In addition, it impaired angiogenesis in chick yolk sac membrane model and chorioallantoic membrane model. In summary, phenobarbital exposure led to shortened lengths of long bones during embryogenesis, which might result from inhibiting mesenchyme differentiation, chondrocyte proliferation, and delaying mineralization by impairing vascular invasion. PMID:27746734

  15. The antioxidant activity of propofol in chicks

    Directory of Open Access Journals (Sweden)

    A.S. Naser

    2015-06-01

    Full Text Available The aim of this study was to detect the antioxidant effects of propofol in chicks by estimation of glutathione concentration in blood plasma, brain and liver as well as total antioxidant capacity and antioxidant effects of propofol in vitro by using hydrogen peroxide as oxidative stress. Propofol at 20 mg/kg, intraperitoneally significantly increased after 4 hours the concentration of glutathione concentration in plasma and brain compared with the control group and with 5 and 10mg propofol groups. Propofol at 5, 10 and 20 mg/kg, i.p significantly increased glutathione concentration in the liver compared with the control group. Propofol at 5, 10 and 20 mg/kg, i.p increased the efflux rate constant by 882, 1031 and 920 %, increased glutathione turnover rate by 880, 1028, and 917 % and decreased the turnover time by 89, 91 and 90% in the liver. In the brain propofol at 5, 10 and 20 mg/kg, i.p increased efflux rate constant as 26, 600 and 2826 % and increased glutathione turnover rate by 29, 616 and 2894 % and a decreased in the turnover time by 21, 86 and 96%. propofol at 10 and 20 mg/kg, i.p significantly increased after 20 hours the TAC in the serum of the chick by 38 and 48%, respectively compared with the control group. Propofol at concentrations of 25, 50 and 100 micromoles / liter decreased erythrocyte hemolysis induced by hydrogen peroxide in vitro 10 micromoles / liter in a concentration depended manner by 25, 49 and 64 % respectively. In conclusion, propofol have antioxidant effect in vivo and in vitro in the chicks.Propofol have a protection against oxidative stress.

  16. Killing day-old chicks? Public opinion regarding potential alternatives

    NARCIS (Netherlands)

    Leenstra, F.; Munnichs, G.M.; Beekman, V.; Vromans, E.; Aramyan, L.; Woelders, H.

    2011-01-01

    Throughout the world, male chicks from layer breeds are killed just after hatching, as they are not profitable as regards the production of meat. The Dutch and European parliaments have insisted on research into possible alternatives to the killing of day-old chicks. In the present study we have inv

  17. Measuring the style of chick lit and literature

    NARCIS (Netherlands)

    Jautze, K.J.

    2014-01-01

    This paper examines to what extent the distribution of the hundred most frequent function words of two novelistic genres (chick lit and literature) gives insight into the genre styles. The results shows that the literary style is more descriptive and informational, whereas the style of the chick-lit

  18. Constraining the neutrino magnetic dipole moment from white dwarf pulsations

    Energy Technology Data Exchange (ETDEWEB)

    Córsico, A.H.; Althaus, L.G. [Grupo de Evolución Estelar y Pulsaciones, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, (1900) La Plata (Argentina); Bertolami, M.M. Miller [Instituto de Astrofísica La Plata, CONICET-UNLP, Paseo del Bosque s/n, (1900) La Plata (Argentina); Kepler, S.O. [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre 91501-970, RS (Brazil); García-Berro, E., E-mail: acorsico@fcaglp.unlp.edu.ar, E-mail: althaus@fcaglp.unlp.edu.ar, E-mail: marcelo@MPA-Garching.MPG.DE, E-mail: kepler@if.ufrgs.br, E-mail: enrique.garcia-berro@upc.edu [Departament de Física Aplicada, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, 08860, Castelldefels (Spain)

    2014-08-01

    Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment (μ{sub ν}) using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. We employ state-of-the-art evolutionary and pulsational codes which allow us to perform a detailed asteroseismological period fit based on fully DB white dwarf evolutionary sequences. Plasmon neutrino emission is the dominant cooling mechanism for this class of hot pulsating white dwarfs, and so it is the main contributor to the rate of change of period with time (Pidot) for the DBV class. Thus, the inclusion of an anomalous neutrino emission through a non-vanishing magnetic dipole moment in these sequences notably influences the evolutionary timescales, and also the expected pulsational properties of the DBV stars. By comparing the theoretical Pidot value with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment with an upper limit of μ{sub ν} ∼< 10{sup -11} μ{sub B}. This bound is somewhat less restrictive than, but still compatible with, other limits inferred from the white dwarf luminosity function or from the color-magnitude diagram of the Globular cluster M5. Further improvements of the measurement of the rate of period change of the dominant pulsation mode of PG 1351+489 will be necessary to confirm our bound.

  19. Peripheral Insulin Doesn’t Alter Appetite of Broiler Chicks

    Directory of Open Access Journals (Sweden)

    Lei Liu

    2016-09-01

    Full Text Available An experiment was conducted to investigate the effect of peripheral insulin treatment on appetite in chicks. Six-d-age chicks with ad libitum feeding or fasting for 3 h before injection received a subcutaneous injection of 0, 1, 3, 5, 10, or 20 IU of insulin or vehicle (saline. The results showed peripheral insulin treatment (1 to 20 IU did not alter significantly the feed intake in chicks under either ad libitum feeding or fasting conditions within 4 h (p>0.05. Compared with the control, plasma glucose concentration was significantly decreased after insulin treatment of 3, 5, 10, and 20 IU for 4 h in chicks with ad libitum feeding (p0.05. All results suggest peripheral administration of insulin has no effect on appetite in chicks.

  20. Neural basis of imprinting behavior in chicks.

    Science.gov (United States)

    Nakamori, Tomoharu; Maekawa, Fumihiko; Sato, Katsushige; Tanaka, Kohichi; Ohki-Hamazaki, Hiroko

    2013-01-01

    Newly hatched chicks memorize the characteristics of the first moving object they encounter, and subsequently show a preference for it. This "imprinting" behavior is an example of infant learning and is elicited by visual and/or auditory cues. Visual information of imprinting stimuli in chicks is first processed in the visual Wulst (VW), a telencephalic area corresponding to the mammalian visual cortex, congregates in the core region of the hyperpallium densocellulare (HDCo) cells, and transmitted to the intermediate medial mesopallium (IMM), a region similar to the mammalian association cortex. The imprinting memory is stored in the IMM, and activities of IMM neurons are altered by imprinting. Imprinting also induces functional and structural plastic changes of neurons in the circuit that links the VW and the IMM. Of these neurons, the activity of the HDCo cells is strongly influenced by imprinting. Expression and modulation of NR2B subunit-containing N-methyl-D-aspartate (NMDA) receptors in the HDCo cells are crucial for plastic changes in this circuit as well as the process of visual imprinting. Thus, elucidation of cellular and molecular mechanisms underlying the plastic changes that occurred in the HDCo cells may provide useful knowledge about infant learning. © 2012 The Authors Development, Growth & Differentiation © 2012 Japanese Society of Developmental Biologists.

  1. The relationship between gene expression of cationic and neutral amino acid transporters in the small intestine of chick embryos and chick breed, development, sex, and egg amino acid concentration.

    Science.gov (United States)

    Zeng, P L; Li, X G; Wang, X Q; Zhang, D X; Shu, G; Luo, Q B

    2011-11-01

    This study was conducted to investigate the gene expression of cationic and neutral amino acid (AA) transporters in the small intestine of chick embryos with different genetic backgrounds [Wenshi Yellow-Feathered chick (WYFC) and White Recessive Rock chick (WRRC)]. The study also investigated the correlation between the abundance of AA transporter mRNA and the AA content of fertilized eggs. Intestinal samples were collected on embryonic d 9, 12, 14, 17, and 19 and the day of hatch. The results showed that, before incubation, the AA content of WRRC eggs was lower (P CAT-1 [solute carrier (SLC) family 7 member 1], CAT-4 (SLC family 7 member 4), rBAT (SLC family 3 member 1), y(+)LAT-1 (SLC family 7 member 7), y(+)LAT-2 (SLC family 7 member 6), LAT-4 (SLC family 43 member 2), and SNAT-2 (SLC family 38 member 2), as detected by real-time reverse transcriptase PCR, was greater (P CAT-1, CAT-4, y(+)LAT-2, and LAT-4 in WYFC and on CAT-4 and B(0)AT-1 (SLC family 6 member 19) mRNA expression in WRRC. In WYFC, only CAT-1 mRNA expression was negatively correlated (r = -0.68 to -0.84, P < 0.05) with all AA content. However, few correlations were detected between AA content and the mRNA expression of multiple transporters in WRRC. These findings provide a comprehensive profile of the temporal and spatial mRNA expression of AA transporters in the small intestine of chick embryos. Few correlations were detected between the AA content of the eggs and mRNA expression of specific AA transporters in the small intestine.

  2. Heartbeat Stars and the Ringing of Tidal Pulsations

    Directory of Open Access Journals (Sweden)

    Hambleton Kelly

    2015-01-01

    Full Text Available With the advent of high precision photometry from satellites such as Kepler and CoRoT, a whole new layer of interesting and astounding astronomical objects has been revealed: heartbeat stars are an example of such objects. Heartbeat stars are eccentric ellipsoidal variables that undergo strong tidal interactions when the stars are almost in contact at the time of closest approach. These interactions deform of the stars and cause a notable light curve variation in the form of a tidal pulse. A subset of these objects (~20% show prominent tidally induced pulsations: pulsations forced by the binary orbit. We now have a fully functional code that models binary star features (using PHOEBE and stellar pulsations simultaneously, enabling a complete and accurate heartbeat star model to be determined. In this paper we show the results of our new code, which uses emcee, a variant of mcmc, to generate a full set of stellar parameters. We further highlight the interesting features of KIC 8164262, including its tidally induced pulsations and resonantly locked pulsations.

  3. Learning from Pulsating Stars: Progress over the Last Century (Abstract)

    Science.gov (United States)

    Smith, H.

    2016-12-01

    (Abstract only) Scarcely more than a century has elapsed since it began to be widely accepted that pulsation plays an important role in the variability of stars. During that century pulsating stars have been used as tools to explore a variety of astrophysical questions, including the determination of distances to other galaxies, the testing of timescales of evolution through the HR diagram, and the identification of the ages and star formation histories of stellar populations. Among the significant early milestones along this investigative path are Henrietta Leavitt's discovery of a relation between the periods and luminosities of Cepheids, Harlow Shapley's proposal that all Cepheids are pulsating stars, and Arthur Stanley Eddington's use of the observed period change of d Cephei to constrain its power source. Today our explorations of pulsating stars are bolstered by long observational histories of brighter variables, surveys involving unprecedentedly large numbers of stars, and improved theoretical analyses. This talk will review aspects of the history and our current understanding of pulsating stars, paying particular attention to RR Lyrae, d Scuti, and Cepheid variables. Observations by AAVSO members have provided insight into several questions regarding the behavior of these stars.

  4. Photometric Survey to Search for Field sdO Pulsators

    CERN Document Server

    Johnson, Christopher B; Wallace, S; O'Malley, C J; Amaya, H; Biddle, L; Fontaine, G

    2013-01-01

    We present the results of a campaign to search for subdwarf O (sdO) star pulsators among bright field stars. The motivation for this project is the recent discovery by Randall et al. (2011), of four rapidly pulsating sdO stars in the globular cluster Omega Cen, with Teff near 50,000 K, 5.4 -0.1 and similar temperatures and gravities. To date, we have found no detectable pulsations at amplitudes above 0.08% (4 times the mean noise level) in any of the 36 field sdO stars that we observed. The presence of pulsations in Omega Cen sdO stars and their apparent absence in seemingly comparable field sdO stars is perplexing. While very suggestive, the significance of this result is difficult to assess more completely right now due to remaining uncertainties about the temperature width and purity of the Omega Cen instability strip and the existence of any sdO pulsators with weaker amplitudes than the current detection limit in globular clusters.

  5. Theoretical rates of pulsation period change in the Galactic Cepheids

    CERN Document Server

    Fadeyev, Yuri A

    2014-01-01

    Theoretical estimates of the rates of radial pulsation period change in Galactic Cepheids with initial masses 5.5M_\\odot <= Mzams <= 13M_\\odot, chemical composition X=0.7, Z=0.02 and periods 1.5 day <= P <= 100 day are obtained from consistent stellar evolution and nonlinear stellar pulsation computations. Pulsational instability was investigated for three crossings of the instability strip by the evolutionary track in the HR diagram. The first crossing occurs at the post-main sequence helium core gravitational contraction stage which proceeds in the Kelvin--Helmholtz timescale whereas the second and the third crossings take place at the evolutionary stage of thermonuclear core helium burning. During each crossing of the instability strip the period of radial pulsations is a quadratic function of the stellar evolution time. Theoretical rates of the pulsation period change agree with observations but the scatter of observational estimates of dP/dt noticeably exceeds the width of the band (\\delta\\lo...

  6. Finding non-eclipsing binaries through pulsational phase modulation

    Science.gov (United States)

    Murphy, Simon J.; Bedding, Timothy R.; Shibahashi, Hiromoto; Kurtz, Donald W.; Kjeldsen, Hans

    2015-09-01

    We present a method for finding binaries among pulsating stars that were observed by the Kepler Mission. We use entire four-year light curves to accurately measure the frequencies of the strongest pulsation modes, then track the pulsation phases at those frequencies in 10-d segments. This produces a series of time-delay measurements in which binarity is apparent as a periodic modulation whose amplitude gives the projected light travel time across the orbit. Fourier analysis of this time-delay curve provides the parameters of the orbit, including the period, eccentricity, angle of ascending node and time of periastron passage. Differentiating the time-delay curve yields the full radial-velocity curve directly from the Kepler photometry, without the need for spectroscopy. We show examples with delta Scuti stars having large numbers of pulsation modes, including one system in which both components of the binary are pulsating. The method is straightforward to automate, thus radial velocity curves can be derived for hundreds of non-eclipsing binary stars from Kepler photometry alone. This contribution is based largely upon the work by Murphy et al. [1], describing the phase-modulation method in detail.

  7. On the polarization properties of magnetar giant flare pulsating tails

    CERN Document Server

    Yang, Yuan-Pei

    2015-01-01

    Three giant flares have been detected so far from soft gamma-ray repeaters, each characterized by an initial short hard spike and a pulsating tail. The observed pulsating tails are characterized by a duration of $\\sim100\\,\\rm{s}$, an isotropic energy of $\\sim 10^{44}\\,\\rm{erg}$, and a pulse period of a few seconds. The pulsating tail emission likely originates from the residual energy after the intense energy release during the initial spike, which forms a trapped fireball composed of a photon-pair plasma in a closed field line region of the magnetars. Observationally the spectra of pulsating tails can be fitted by the superposition of a thermal component and a power-law component, with the thermal component dominating the emission in the early and late stages of the pulsating tail observations. In this paper, assuming that the trapped fireball is from a closed field line region in the magnetosphere, we calculate the atmosphere structure of the optically-thick trapped fireball and the polarization properties ...

  8. Porcine embryonic stem cells

    DEFF Research Database (Denmark)

    Hall, Vanessa Jane

    2008-01-01

    The development of porcine embryonic stem cell lines (pESC) has received renewed interest given the advances being made in the production of immunocompatible transgenic pigs. However, difficulties are evident in the production of pESCs in-vitro. This may largely be attributable to differences...

  9. Interdigital cell death in the embryonic limb is associated with depletion of Reelin in the extracellular matrix

    OpenAIRE

    2013-01-01

    Interdigital cell death is a physiological regression process responsible for sculpturing the digits in the embryonic vertebrate limb. Changes in the intensity of this degenerative process account for the different patterns of interdigital webbing among vertebrate species. Here, we show that Reelin is present in the extracellular matrix of the interdigital mesoderm of chick and mouse embryos during the developmental stages of digit formation. Reelin is a large extracellular glycoprotein which...

  10. Concurrent Connection of Embryonic Chick Heart Using a Microfluidic Device for Organ-Explant-Chip

    OpenAIRE

    Owaki, Hirofumi; Masuda, Taisuke; Kawahara, Tomohiro; Miyasaka, Kota; Ogura, Toshihiko; Arai, Fumihito

    2013-01-01

    We propose a concurrent microvascular connection method called suction-induced vascular fixation (SVF) method for the achievement of Organ-Explant-Chip which is a biologically-designed simulator having biological materials such as cells, tissues, and organs. The advantages of proposed method with using a microfluidic device are as follows: (1) operation of flexible objects (blood vessels), (2) alignment the blood vessels concurrently, and (3) reduction of the DOFs of the blood vessels. From t...

  11. Retinoic acid is a potential dorsalising signal in the late embryonic chick hindbrain

    Directory of Open Access Journals (Sweden)

    Maden Malcolm

    2007-12-01

    Full Text Available Abstract Background Human retinoic acid teratogenesis results in malformations of dorsally derived hindbrain structures such as the cerebellum, noradrenergic hindbrain neurons and the precerebellar system. These structures originate from the rhombic lip and adjacent dorsal precursor pools that border the fourth ventricle roofplate. While retinoic acid synthesis is known to occur in the meninges that blanket the hindbrain, the particular sensitivity of only dorsal structures to disruptions in retinoid signalling is puzzling. We therefore looked for evidence within the neural tube for more spatiotemporally specific signalling pathways using an in situ hybridisation screen of known retinoic acid pathway transcripts. Results We find that there are highly restricted domains of retinoic acid synthesis and breakdown within specific hindbrain nuclei as well as the ventricular layer and roofplate. Intriguingly, transcripts of cellular retinoic acid binding protein 1 are always found at the interface between dividing and post-mitotic cells. By contrast to earlier stages of development, domains of synthesis and breakdown in post-mitotic neurons are co-localised. At the rhombic lip, expression of the mRNA for retinoic acid synthesising and catabolising enzymes is spatially highly organised with respect to the Cath1-positive precursors of migratory precerebellar neurons. Conclusion The late developing hindbrain shows patterns of retinoic acid synthesis and use that are distinct from the well characterised phase of rostrocaudal patterning. Selected post-mitotic populations, such as the locus coeruleus, appear to both make and break down retinoic acid suggesting that a requirement for an autocrine, or at least a highly localised paracrine signalling network, might explain its acute sensitivity to retinoic acid disruption. At the rhombic lip, retinoic acid is likely to act as a dorsalising factor in parallel with other roofplate signalling pathways. While its precise role is unclear, retinoic acid is potentially well placed to regulate temporally determined cell fate decisions within the rhombic lip precursor pool.

  12. Finding the Instability Strip for Accreting Pulsating White Dwarfs from HST and Optical Observations

    CERN Document Server

    Szkody, Paula; Gansicke, Boris T; Henden, Arne; Templeton, Matthew; Holtzman, Jon; Montgomery, Michael H; Howell, Steve B; Nitta, Atsuko; Sion, Edward M; Schwartz, Richard D; Dillon, William

    2010-01-01

    Time-resolved low resolution Hubble Space Telescope ultraviolet spectra together with ground-based optical photometry and spectra are used to constrain the temperatures and pulsation properties of six cataclysmic variables containing pulsating white dwarfs. Combining our temperature determinations for the five pulsating white dwarfs that are several years past outburst with past results on six other systems shows that the instability strip for accreting pulsating white dwarfs ranges from 10,500-15,000K, a wider range than evident for ZZ Ceti pulsators. Analysis of the UV/optical pulsation properties reveals some puzzling aspects. While half the systems show high pulsation amplitudes in the UV compared to their optical counterparts, others show UV/optical amplitude ratios that are less than one or no pulsations at either wavelength region.

  13. Search for pulsations in the LMXB EXO 0748-676

    Institute of Scientific and Technical Information of China (English)

    Chetana Jain; Biswajit Paul

    2011-01-01

    We present here results from our search for X-ray pulsations of the neutron star in the low mass X-ray binary EXO 0748-676 at a frequency near the burstoscillation frequency of 44.7 Hz.Using the observations made with the Proportional Counter Array onboard the Rossi X-ray Timing Explorer, we did not find any pulsations in the frequency band of 44.4 Hz to 45.0 Hz and obtained a 3σ upper limit of 0.47% on the pulsed fraction for any possible underlying pulsation in this frequency band.We also discuss the importance of EXO 0748-676 as a promising source for the detection of Gravitational Waves.

  14. Prediction of gas pulsation of an industrial compressor

    Institute of Scientific and Technical Information of China (English)

    Heuicheol; Kim; Mi-Gyung; Cho; Jaehong; Park; Cheolho; Bai; Jaesool; Shim

    2013-01-01

    The measurement and prediction of gas pulsations are performed along the discharge pipeline of a reciprocating compressor for a refrigerator. A regression based experimental model of the one-dimensional acoustic field is developed. First, the conventional method for gas pulsation measurement and prediction, which separates the incident and reflected wave of acoustic waves traveling in the frequency domain, is discussed. Then, regression based on our proposed simple model, which is able to predict gas pulsation compared to the conventional method, is introduced for the analysis of a reciprocating compressor(The conventional method requires the value of sound speed in the piping line for the reciprocating compressor). A numerical prediction is made for the regression method. Three power spectrum values along the discharge pipeline are used for analysis, and two values are used for verification. Our results are in a good agreement with the conventional method.

  15. Period Changes and Evolution in Pulsating Variable Stars

    Science.gov (United States)

    Neilson, H. R.; Percy, J. R.; Smith, H. A.

    2016-12-01

    We review ways in which observations of the changing periods of pulsating variable stars can be used to detect and directly measure their evolution. We briefly describe the two main techniques of analysis-(O-C) analysis and wavelet analysis - and results for pulsating variable star types which are reasonably periodic: type I and II Cepheids, RR Lyrae stars, beta Cephei stars, and Mira stars. We comment briefly on delta Scuti stars and pulsating white dwarfs. For some of these variable star types, observations agree approximately with the predictions of evolutionary models, but there still exist significant areas of disagreement that challenge future models of stellar evolution. There may be a need, for instance, to include processes such as rotation, mass loss, and magnetic fields. There may also be non-evolutionary processes which are contributing to the period changes.

  16. Period Changes and Evolution in Pulsating Variable Stars

    CERN Document Server

    Neilson, Hilding R; Smith, Horace A

    2016-01-01

    We review ways in which observations of the changing periods of pulsating variable stars can be used to detect and directly measure their evolution. We briefly describe the two main techniques of analysis -- (O-C) analysis and wavelet analysis -- and results for pulsating variable star types which are reasonably periodic: type I and II Cepheids, RR Lyrae stars, beta Cephei stars, and Mira stars. We comment briefly on delta Scuti stars and pulsating white dwarfs. For some of these variable star types, observations agree approximately with the predictions of evolutionary models, but there still exist significant areas of disagreement that challenge future models of stellar evolution. There may be a need, for instance, to include processes such as rotation, mass loss, and magnetic fields. There may also be non-evolutionary processes which are contributing to the period changes.

  17. Stellar Pulsations, Impact of New Instrumentation and New Insights

    CERN Document Server

    Garrido, R; Balona, L; Christensen-Dalsgaard, J; 20th Stellar Pulsation Conference Series

    2013-01-01

    Analyses of photometric time series obtained from the MOST, CoRoT and Kepler space missions were presented at the 20th conference on Stellar Pulsations (Granada, September 2011). These results are leading to a re-appraisal of our views on stellar pulsation in some stars and posing some new and unexpected challenges. The very important and exciting role played by innovative ground-based observational techniques, such as interferometric measurements of giant pulsating stars and high-resolution spectroscopy in the near infrared, is also discussed. These Proceedings are distinguished by the format of the conference, which brings together a variety of related but different topics not found in other meetings of this nature.

  18. Nonlinear simulations of the convection-pulsation coupling

    CERN Document Server

    Gastine, T

    2011-01-01

    In cold Cepheids close to the red edge of the classical instability strip, a strong coupling between the stellar pulsations and the surface convective motions occurs. This coupling is by now poorly described by 1-D models of convection, the so-called "time-dependent convection models" (TDC). The intrinsic weakness of such models comes from the large number of unconstrained free parameters entering in the description of turbulent convection. A way to overcome these limits is to compute two-dimensional direct simulations (DNS), in which all the nonlinearities are correctly solved. Two-dimensional DNS of the convection-pulsation coupling are presented here. In an appropriate parameter regime, convective motions can actually quench the radial pulsations of the star, as suspected in Cepheids close to the red edge of the instability strip. These nonlinear simulations can also be used to determine the limits and the relevance of the TDC models.

  19. On the pulsation modes and masses of RGB OSARGs

    Directory of Open Access Journals (Sweden)

    Saio H.

    2013-03-01

    Full Text Available OSARG (OGLE Small Amplitude Red Giants variables are RGB or AGB stars that show multi-periodic light variations with periods of about 10-100 days. Comparing linear nonadiabatic pulsation periods and period ratios with observed ones, we determined pulsation modes and masses of the RGB OSARG variables in the LMC. We found that pulsations of OSARGs involve radial 1st to 3rd overtones, p4 of l = 1, and p2 of l = 2 modes. The range of mass isfound to be 0.9-1.4M⊙ for RGB OSARGs and their mass-luminosity relation is logL/L⊙ = 0.79 M/M⊙ + 2.2.

  20. New DA white dwarf evolutionary models and their pulsational properties

    CERN Document Server

    Corsico, A H; Benvenuto, O G; Serenelli, A M

    2001-01-01

    In this letter we investigate the pulsational properties of ZZ Ceti stars on the basis of new white dwarf evolutionary models calculated in a self-consistent way with the predictions of time dependent element diffusion and nuclear burning. In addition, full account is taken of the evolutionary stages prior to the white dwarf formation. Emphasis is placed on the trapping properties of such models. By means of adiabatic, non-radial pulsation calculations, we find, as a result of time dependent diffusion, a much weaker mode trapping effect, particularly for the high-period regime of the pulsation g-spectrum. This result is valid at least for models with massive hydrogen-rich envelopes. Thus, mode trapping would not be an effective mechanism to explain the fact that all the high periods expected from standard models of stratified white dwarfs are not observed in the ZZ Ceti stars.

  1. Finding the First Cosmic Explosions. III. Pair-Pulsational Supernovae

    CERN Document Server

    Whalen, Daniel J; Even, Wesley; Woosley, S E; Heger, Alexander; Stiavelli, Massimo; Fryer, Chris L

    2013-01-01

    Population III supernovae have been the focus of growing attention because of their potential to directly probe the properties of the first stars, particularly the most energetic events that can be seen at the edge of the observable universe. But until now pair-pulsation supernovae, in which explosive thermonuclear burning in massive stars fails to unbind them but can eject their outer layers into space, have been overlooked as cosmic beacons at the earliest redshifts. These shells can later collide and, like Type IIn supernovae, produce superluminous events in the UV at high redshifts that could be detected in the near infrared today. We present numerical simulations of a 110 M$_{\\odot}$ pair-pulsation explosion done with the Los Alamos radiation hydrodynamics code RAGE. We find that collisions between consecutive pair pulsations are visible in the near infrared out to z $\\sim$ 15 - 20 and can probe the earliest stellar populations at cosmic dawn.

  2. Outbursts in Two New Cool Pulsating DA White Dwarfs

    Science.gov (United States)

    Bell, Keaton J.; Hermes, J. J.; Montgomery, M. H.; Gentile Fusillo, N. P.; Raddi, R.; Gänsicke, B. T.; Winget, D. E.; Dennihy, E.; Gianninas, A.; Tremblay, P.-E.; Chote, P.; Winget, K. I.

    2016-10-01

    The unprecedented extent of coverage provided by Kepler observations recently revealed outbursts in two hydrogen-atmosphere pulsating white dwarfs (DAVs) that cause hours-long increases in the overall mean flux of up to 14%. We have identified two new outbursting pulsating white dwarfs in K2, bringing the total number of known outbursting white dwarfs to four. EPIC 211629697, with {T}{eff} = 10,780 ± 140 K and {log} g = 7.94 ± 0.08, shows outbursts recurring on average every 5.0 days, increasing the overall flux by up to 15%. EPIC 229227292, with {T}{eff} = 11,190 ± 170 K and {log} g = 8.02 ± 0.05, has outbursts that recur roughly every 2.4 days with amplitudes up to 9%. We establish that only the coolest pulsating white dwarfs within a small temperature range near the cool, red edge of the DAV instability strip exhibit these outbursts.

  3. Articulated pipes conveying fluid pulsating with high frequency

    DEFF Research Database (Denmark)

    Jensen, Jakob Søndergaard

    1999-01-01

    Stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component is investigated. The non-autonomous model equations are converted into autonomous equations by approximating the fast excitation terms with slowly varying terms. The downward hanging...... pipe position will lose stability if the mean flow speed exceeds a certain critical value. Adding a pulsating component to the fluid flow is shown to stabilize the hanging position for high values of the ratio between fluid and pipe-mass, and to marginally destabilize this position for low ratios...

  4. The pulsations of the Sun and the stars

    CERN Document Server

    Rozelot, Jean-Pierre

    2011-01-01

    This volume of lecture notes brings together the knowledge on pulsations of the Sun and the stars, with a particular emphasis on recent observations and modelling, and on the influence of pulsations of other physical processes. The book begins with an extensive introduction to helioseismology. The solar cycle and gravity modes are discussed before the focus is widened from helioseismology to asteroseismology which is detailed in a series of specific chapters. Based on courses given at a graduate school, these tutorial lecture notes will be of interest and useful to a rather broad audience of scientists and students.

  5. Flame fronts in Supernovae Ia and their pulsational stability

    CERN Document Server

    Glazyrin, S I; Dolgov, A D

    2013-01-01

    The structure of the deflagration burning front in type Ia supernovae is considered. The parameters of the flame are obtained: its normal velocity and thickness. The results are in good agreement with previous work of different authors. After that the question of pulsational instability of the flame subject to plane perturbations is considered. The flame can be unstable if hydrodynamics can be ignored, e.g. in solid-body propellants. However, with account of hydrodynamics we find that the flame in type Ia supernovae is pulsationally stable with realistic parameters of reactions and thermal conduction.

  6. Latitude distribution of nonradial pulsations in rapidly rotating B stars

    Science.gov (United States)

    Jankov, S.; Mathias, P.; Domiciano de Souza, A., Jr.; Uytterhoeven, K.; Aerts, C.

    2004-05-01

    We present a method for the analysis of latitude distribution associated with temperature and/or velocity perturbations of the stellar surface due to non-radial pulsation (NRP) modes in rapidly rotating B stars. The technique is applied together with Fourier Doppler Imaging (FDI) to high resolution and high signal-to-noise ratio spectroscopic observations of ɛ Per. The main advantage of this approach is that it decomposed complex multi-periodic line profile variations into single components, allowing the detailed analysis of each mode seperately. We study the 10.6-d-1 frequency that is particularly important for modal analysis of non-radial pulsations in the star.

  7. Cycles of self-pulsations in a photonic integrated circuit.

    Science.gov (United States)

    Karsaklian Dal Bosco, Andreas; Kanno, Kazutaka; Uchida, Atsushi; Sciamanna, Marc; Harayama, Takahisa; Yoshimura, Kazuyuki

    2015-12-01

    We report experimentally on the bifurcation cascade leading to the appearance of self-pulsation in a photonic integrated circuit in which a laser diode is subjected to delayed optical feedback. We study the evolution of the self-pulsing frequency with the increase of both the feedback strength and the injection current. Experimental observations show good qualitative accordance with numerical results carried out with the Lang-Kobayashi rate equation model. We explain the mechanism underlying the self-pulsations by a phenomenon of beating between successive pairs of external cavity modes and antimodes.

  8. Search for Optical Pulsations in PSR J0337+1715

    CERN Document Server

    Strader, M J; Meeker, S R; Szypryt, P; Walter, A B; van Eyken, J C; Ulbricht, G; Stoughton, C; Bumble, B; Kaplan, D L; Mazin, B A

    2016-01-01

    We report on a search for optical pulsations from PSR J0337+1715 at its observed radio pulse period. PSR J0337+1715 is a millisecond pulsar (2.7 ms spin period) in a triple hierarchical system with two white dwarfs, and has a known optical counterpart with g-band magnitude 18. The observations were done with the Array Camera for Optical to Near-IR Spectrophotometry (ARCONS) at the 200" Hale telescope at Palomar Observatory. No significant pulsations were found in the range 4000-11000 angstroms, and we can limit pulsed emission in g-band to be fainter than 25 mag.

  9. First Kepler results on compact pulsators - V. Slowly pulsating subdwarf B stars in short-period binaries

    DEFF Research Database (Denmark)

    Kawaler, Stephen D.; Reed, Michael D.; Østensen, Roy H.

    2010-01-01

    The survey phase of the Kepler Mission includes a number of hot subdwarf B (sdB) stars to search for non-radial pulsations. We present our analysis of two sdB stars that are found to be g-mode pulsators of the V1093 Her class. These two stars also display the distinct irradiation effect typical...... of sdB stars with a close M-dwarf companion with orbital periods of less than half a day. Because the orbital period is so short, the stars should be in synchronous rotation, and if so, the rotation period should imprint itself on the multiplet structure of the pulsations. However, we do not find clear...... evidence for such rotational splitting. Though the stars do show some frequency spacings that are consistent with synchronous rotation, they also display multiplets with splittings that are much smaller. Longer-duration time series photometry will be needed to determine if those small splittings...

  10. The chick embryo chorioallantoic membrane (CAM) assay.

    Science.gov (United States)

    Ribatti, Domenico

    2017-06-01

    During avian development the mesodermal layers of the allantois and chorion fuse to form the chorioallantoic membrane (CAM). This structure rapidly expands generating a rich vascular network that provides an interface for gas and waste exchange. The CAM allows to study tissue grafts, tumor growth and metastasis, drugs delivery and toxicologic analysis, and angiogenic and anti-angiogenic molecules. The CAM is relatively simple, quick, and low-cost model that allows screening of a large number of pharmacological samples in a short time; does not require administrative procedures for obtaining ethics committee approval for animal experimentation. Moreover, being naturally immunodeficient, the chick embryo may receive transplantations from different tissues and species, without immune responses. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. An evaluation of the chick cardiomyocyte micromass system for identification of teratogens in a blind trial.

    Science.gov (United States)

    Hurst, Helen; Clothier, Richard H; Pratten, Margaret

    2009-12-01

    The chick micromass culture system has advantages over the validated rat system - ready availability and non-culling of the donor parent - but needs to give comparable results. This study confirmed comparability and the ability to extend the system to cover cardiac effects. It was also compared with the validated embryonic stem cell cardiomyocyte model. A teratogen and paired non-teratogen with known in vivo effects were used. Differential effects were measured via changes in cell protein content, cell viability (resazurin reduction and neutral red uptake), and cell contractility. Results showed that teratogens [L-ethionine, 5-fluorouracil and sulphisoxazole] could be distinguished from non-teratogens [DL-methionine, 6-methyluracil and sulphanilamide respectively]. Dichloroacetone and dichloropropanol affected embryonic stem cells but not the micromass; dichloropropanol had a greater effect than dichloroacetone. This approach revealed differential effects on contractility independent of effects on activity/viability, whilst the total cell protein remained unchanged. We suggest that pre-validation of this system should be examined.

  12. Effects of heat stress on day-old broiler chicks.

    Science.gov (United States)

    Ernst, R A; Weathers, W W; Smith, J

    1984-09-01

    Short-term heat stress can occur when chicks are transported from the hatchery to growing facilities. Two experiments were conducted to determine the possible effects of short-term heat stress on growth and feed conversion of broiler (Hubbard X Hubbard) chicks. The heat stress was accomplished by placing chicks in Jamesway 252 incubators at dry bulb temperatures ranging from 40 to 45 C for variable times. Growth, feed consumption, and mortality were measured for 16 days following the heat stress. Short sublethal heat stress significantly reduced growth rate to 16 days in these experiments without any effect on feed conversion ratio. The results indicate that the hatchery industry should avoid overheating chicks even for periods as short as 1 hr.

  13. Effect of refuge supplement on Audouin's gull chick survival

    Directory of Open Access Journals (Sweden)

    Jordi Prieto

    2003-07-01

    Full Text Available One of the main threats to Audouin´s gull (Larus audouinii at Chafarinas Islands is predation on eggs and chicks by the yellow-legged gull (Larus cachinnans. During the 1999 and 2000 breeding seasons we tested the effects of supplementary refuge availability on chick survival. Well before the laying period, nine adjacent enclosures were erected inside Audouin´s gull´s breeding grounds and some of them were supplied with artificial refuges. Our results showed significantly greater chick survival in the enclosures with artificial refuges than in control ones. In 2000, an overall lower breeding success of Audouin´s gull and a dilution of the refuge effect were observed. These results were probably related to food-shortage that year. We suggest that, along with other factors, an increase in refuge availability may significantly enhance Audouin´s gull chick survival.

  14. Transformerless photovoltaic inverters with leakage current and pulsating power elimination

    DEFF Research Database (Denmark)

    Tang, Yi; Yao, Wenli; Wang, H.;

    2015-01-01

    that is inherent in single-phase PV systems. By properly injecting CM voltages to the output filter capacitors, the pulsating power can be decoupled from the dc-link. Therefore, it is possible to use long lifetime film capacitors instead of electrolytic capacitors to improve the reliability of the PV system...

  15. The triple-mode pulsating variable V823 Cassiopeiae

    Science.gov (United States)

    Jurcsik, J.; Szeidl, B.; Váradi, M.; Henden, A.; Hurta, Zs.; Lakatos, B.; Posztobányi, K.; Klagyivik, P.; Sódor, Á.

    2006-01-01

    Using extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection affects the mode coupling behaviour. The P1/P0 period ratio of V823 Cas has an “out of range” value if compared with the period ratios of the known double mode pulsators, while the P2/P1 period ratio is normal. The periods and period ratios cannot be consistently interpreted without conflict with pulsation and/or evolution models. We describe this failure with the suggestion that at present, the periods of V823 Cas are in a transient, resonance affected state, thus do not reflect the true parameters of the object. The anomalous period change behaviour of the fundamental and second overtone modes supports this idea. We have also raised the possibility that a f0 +f2 = 2f1 resonance may act in triple mode pulsators.

  16. EXOTIME: searching for planets around pulsating subdwarf B stars

    CERN Document Server

    Schuh, Sonja; Lutz, Ronny; Loeptien, Bjoern; Green, Elizabeth M; Ostensen, Roy H; Leccia, Silvio; Kim, Seung-Lee; Fontaine, Gilles; Charpinet, Stephane; Francoeur, Myriam; Randall, Suzanna; Rodriguez-Lopez, Cristina; van Grootel, Valerie; Odell, Andrew P; Paparo, Margit; Bognar, Zsofia; Papics, Peter; Nagel, Thorsten; Beeck, Benjamin; Hundertmark, Markus; Stahn, Thorsten; Dreizler, Stefan; Hessman, Frederic V; Dall'Ora, Massimo; Mancini, Dario; Cortecchia, Fausto; Benatti, Serena; Claudi, Riccardo; Janulis, Rimvydas; 10.1007/s10509-010-0356-4

    2010-01-01

    In 2007, a companion with planetary mass was found around the pulsating subdwarf B star V391 Pegasi with the timing method, indicating that a previously undiscovered population of substellar companions to apparently single subdwarf B stars might exist. Following this serendipitous discovery, the EXOTIME (http://www.na.astro.it/~silvotti/exotime/) monitoring program has been set up to follow the pulsations of a number of selected rapidly pulsating subdwarf B stars on time-scales of several years with two immediate observational goals: 1) determine Pdot of the pulsational periods P 2) search for signatures of substellar companions in O-C residuals due to periodic light travel time variations, which would be tracking the central star's companion-induced wobble around the center of mass. These sets of data should therefore at the same time: on the one hand be useful to provide extra constraints for classical asteroseismological exercises from the Pdot (comparison with "local" evolutionary models), and on the othe...

  17. M dwarf search for pulsations within Kepler GO program

    CERN Document Server

    Rodríguez-López, C; MacDonald, J; Amado, P J; Carosso, A

    2014-01-01

    We present the analysis of four M dwarf stars -plus one M giant that seeped past our selection criteria- observed in Cycle 3 of Kepler Guest Observer program (GO3) in a search for intrinsic pulsations. Stellar oscillations in M dwarfs were theoretically predicted by Rodr\\'iguez-L\\'opez et al. (2012) to be in the range ~20-40 min and ~4-8 h, depending on the age and the excitation mechanism. We requested Kepler short cadence observations to have an adequate sampling of the oscillations. The targets were chosen on the basis of detectable rotation in the initial Kepler results, biasing towards youth.The analysis reveals no oscillations attributable to pulsations at a detection limit of several parts per million, showing that either the driving mechanisms are not efficient in developing the oscillations to observable amplitudes, or that if pulsations are driven, the amplitudes are very low. The size of the sample, and the possibility that the instability strip is not pure, allowing the coexistence of pulsators an...

  18. Experimental and numerical study of pulsating transversal jets

    Science.gov (United States)

    Goldfeld, M. A.; Fedorova, N. N.; Fedorchenko, I. A.; Pozdnyakov, G. A.; Timofeev, K. Yu.; Zhakharova, Yu. V.

    2015-06-01

    Paper presents results of joint experimental and numerical investigation of pulsating jet penetration into still air and supersonic flow. Goal of the study is to investigate two-dimensional (2D) Hartmann generator (HG) properties and clear up its possibilities in providing better mixing between air and secondary (injected) gases.

  19. Solar Microwave and Geomagnetic Field Pulsations as Space Weather Factors

    Science.gov (United States)

    Snegirev, S. D.; Fridman, V. M.; Sheiner, O. A.

    The procedure of short-term prediction of main solar flares was created on the basis of temporal behavior of long-period microwave pulsations [Kobrin et al., 1997]. At the same time it was shown that before these flares one could observe long-period (T > 20 min) pulsations of geomagnetic field [Kobrin et al, 1985]. The resemblance between microwave and geomagnetic pulsations (duration and temporal behaviour) allows us to propose the common nature of these variations: the reflection of solar energy accumulation and instabilities in solar centers of activity. To be an important factor of Space Weather above mentioned pulsations can be useful for constructing the procedures to predict the near Earth's conditions. This work was supported by the Russian Foundation for Fundamental Research and Russian Federal Programm "Astronomy" (grant N 1.5.5.5). Kobrin M.M, Malygin V.I., Snegirev S.D. Plan. Space Sci., 33, N11, p. 1251 (1985). Kobrin M.M., Pakhomov V.V., Snegirev S.D., Fridman V.M., Sheiner O.A. Proc. Workshop `STPW-96', Tokyo: RCW, p. 200 (1997).

  20. Pressure pulsations in reciprocating pump piping systems Part 1: Modelling

    CERN Document Server

    Shu, Jian-Jun; Edge, Kevin A

    2014-01-01

    A distributed parameter model of pipeline transmission line behaviour is presented, based on a Galerkin method incorporating frequency-dependent friction. This is readily interfaced to an existing model of the pumping dynamics of a plunger pump to allow time-domain simulations of pipeline pressure pulsations in both suction and delivery lines. A new model for the pump inlet manifold is also proposed.

  1. The triple-mode pulsating variable V823 Cas

    CERN Document Server

    Jurcsik, J; Varadi, M; Henden, A; Hurta, Z; Lakatos, B; Posztobanyi, K; Klagyivik, P; Sodor, A; Hurta, Zs.

    2005-01-01

    Based on extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection as suggested by Antonello & Aikawa (1998) affects the mode coupling behaviour. The P1/P0 period ratio of V823 Cas has an "out of range" value if compared with the period ratios of the known double mode pulsators, while the P2/P1 period ratio is normal. The periods and period ratios cannot be consistently interpret without conflict with pulsation and/or evolution models. We attempt to interpret this failure by the suggestion that at present, the periods of V823 Cas are in a transient, resonance affected state, thus do not reflect the true parameters of the object. The anomalous period change behaviour of the fundamental and second overtone modes supports this idea. We have also raised the possibility that a f0 + f2 = 2f1 resonance may act in triple mode pulsators.

  2. First Kepler results on compact pulsators VI. Targets in the final half of the survey phase

    DEFF Research Database (Denmark)

    H. Østensen, R.; Silvotti, R.; Charpinet, S.;

    2011-01-01

    We present results from the final six months of a survey to search for pulsations in white dwarfs and hot subdwarf stars with the Kepler spacecraft. Spectroscopic observations are used to separate the objects into accurate classes, and we explore the physical parameters of the subdwarf B (sd....... No V361 Hya type of short-period pulsating sdB stars were found in this half, leaving us with a total of one single multiperiodic V361 Hya and 13 V1093 Her pulsators for the full survey. Except for the sdB pulsators, no other clearly pulsating hot subdwarfs or white dwarfs were found, although a few...

  3. Predicting chick body mass by artificial intelligence-based models

    Directory of Open Access Journals (Sweden)

    Patricia Ferreira Ponciano Ferraz

    2014-07-01

    Full Text Available The objective of this work was to develop, validate, and compare 190 artificial intelligence-based models for predicting the body mass of chicks from 2 to 21 days of age subjected to different duration and intensities of thermal challenge. The experiment was conducted inside four climate-controlled wind tunnels using 210 chicks. A database containing 840 datasets (from 2 to 21-day-old chicks - with the variables dry-bulb air temperature, duration of thermal stress (days, chick age (days, and the daily body mass of chicks - was used for network training, validation, and tests of models based on artificial neural networks (ANNs and neuro-fuzzy networks (NFNs. The ANNs were most accurate in predicting the body mass of chicks from 2 to 21 days of age after they were subjected to the input variables, and they showed an R² of 0.9993 and a standard error of 4.62 g. The ANNs enable the simulation of different scenarios, which can assist in managerial decision-making, and they can be embedded in the heating control systems.

  4. Asteroseismology of hybrid δ Scuti-γ Doradus pulsating stars

    Science.gov (United States)

    Sánchez Arias, J. P.; Córsico, A. H.; Althaus, L. G.

    2017-01-01

    Context. Hybrid δ Scuti-γ Doradus pulsating stars show acoustic (p) oscillation modes typical of δ Scuti variable stars, and gravity (g) pulsation modes characteristic of γ Doradus variable stars simultaneously excited. Observations from space missions such as MOST, CoRoT, and Kepler have revealed a large number of hybrid δ Scuti-γ Doradus pulsators, thus paving the way for an exciting new channel of asteroseismic studies. Aims: We perform detailed asteroseismological modelling of five hybrid δ Scuti-γ Doradus stars. Methods: A grid-based modeling approach was employed to sound the internal structure of the target stars using stellar models ranging from the zero-age main sequence to the terminal-age main sequence, varying parameters such as stellar mass, effective temperature, metallicity and core overshooting. Their adiabatic radial (ℓ = 0) and non-radial (ℓ = 1,2,3) p and g mode periods were computed. Two model-fitting procedures were used to search for asteroseismological models that best reproduce the observed pulsation spectra of each target star. Results: We derive the fundamental parameters and the evolutionary status of five hybrid δ Scuti-γ Doradus variable stars recently observed by the CoRoT and Kepler space missions: CoRoT 105733033, CoRoT 100866999, KIC 11145123, KIC 9244992, and HD 49434. The asteroseismological model for each star results from different criteria of model selection, in which we take full advantage of the richness of periods that characterises the pulsation spectra for this kind of star.

  5. ON THE POLARIZATION PROPERTIES OF MAGNETAR GIANT FLARE PULSATING TAILS

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuan-Pei [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Zhang, Bing, E-mail: yypspore@gmail.com, E-mail: zhang@physics.unlv.edu [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)

    2015-12-10

    Three giant flares have been detected so far from soft gamma-ray repeaters, each characterized by an initial short hard spike and a pulsating tail. The observed pulsating tails are characterized by a duration of ∼100 s, an isotropic energy of ∼10{sup 44} erg, and a pulse period of a few seconds. The pulsating tail emission likely originates from the residual energy after the intense energy release during the initial spike, which forms a trapped fireball composed of a photon-pair plasma in a closed-field-line region of the magnetars. Observationally the spectra of pulsating tails can be fitted by the superposition of a thermal component and a power-law component, with the thermal component dominating the emission in the early and late stages of the pulsating-tail observations. In this paper, assuming that the trapped fireball is from a closed-field-line region in the magnetosphere, we calculate the atmospheric structure of the optically thick trapped fireball and the polarization properties of the trapped fireball. By properly treating the photon propagation in a hot, highly magnetized, electron–positron pair plasma, we tally photons in two modes (O mode and E mode) at a certain observational angle through Monte Carlo simulations. Our results suggest that the polarization degree depends on the viewing angle with respect to the magnetic axis of the magnetar, and can be as high as Π ≃ 30% in the 1–30 keV band, and Π ≃ 10% in the 30–100 keV band, if the line of sight is perpendicular to the magnetic axis.

  6. Effects of eggshell cuticle removal and incubation humidity on embryonic development and hatchability of broilers.

    Science.gov (United States)

    Peebles, E D; Brake, J; Gildersleeve, R P

    1987-05-01

    The effects of eggshell cuticle removal and two levels of incubation humidity 28.3 C [50% relative humidity (RH)] and 30.0 C (55% RH) wetbulb temperature (WB) on embryonic mortality and hatchability were determined from broiler hatching eggs laid during 38, 42, 48, and 54 weeks of age. Variables measured were: egg weight loss during the first 17 days of incubation, hatch at Days 19.5 and 20.5 of incubation, hatch of fertile eggs, stage of embryonic mortality, and chick weight at 21.5 days of incubation. Day 0 to 17 percentage egg weight loss was increased when the incubation humidity was lowered and the loss was greater than that observed after cuticle removal. A greater percentage of chicks hatched on Day 19.5 at 28.3 C than at 30.0 C WB. The percentage hatch of 38-week fertile eggs was improved at the higher humidity; the higher humidity also decreased late dead and increased pipped embryonic mortalities. Cuticle removal decreased early dead and increased late dead mortality. At Week 38 cuticle removal and lower humidity resulted in a decrease in chick weight at 21.5 days of incubation. For Weeks 42, 48, and 54 combined, pipped mortality was increased by higher humidity and late dead mortality was increased by cuticle removal. Water loss from the egg was increased by cuticle removal or by lowering incubation humidity from 30.0 C to 28.3 C WB, or by both, but lowering humidity was more effective. Changes in humidity and cuticle removal may affect vital gas exchange to different degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Continuous vs. pulsating flow boiling. Part 2: Statistical comparison using response surface methodology

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Meyer, Knud Erik

    2016-01-01

    Response surface methodology is used to investigate an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The flow pulsations are introduced by a flow modulating expansion device and compared with the baseline continuous flow provided by a stepper-motor exp......Response surface methodology is used to investigate an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The flow pulsations are introduced by a flow modulating expansion device and compared with the baseline continuous flow provided by a stepper...... pulsations is statistically significant in terms of the time-averaged flow boiling heat transfer coefficient. The cycle time range from 1 s to 9 s for the pulsations. The results show that the effect of fluid flow pulsations is statistically significant, disregarding the lowest heat flux measurements...

  8. Indirect imaging of nonradial pulsations in a rapidly oscillating Ap star

    CERN Document Server

    Kochukhov, O P

    2004-01-01

    Many types of stars show periodic variations of radius and brightness, which are commonly referred to as `stellar pulsations'. Observed pulsational characteristics are determined by fundamental stellar parameters. Consequently, investigations of stellar pulsations provide a unique opportunity to verify and refine our understanding of the evolution and internal structure of stars. However, a key boundary condition for this analysis -- precise information about the geometry of pulsations in the outer stellar envelopes -- has been notoriously difficult to secure. Here we demonstrate that it is possible to solve this problem by constructing an `image' of the pulsation velocity field from time series observations of stellar spectra. This technique is applied to study the geometry of nonradial pulsations in a prototype magnetic oscillating (roAp) star HR 3831. Our velocity map directly demonstrates an alignment of pulsations with the axis of the global magnetic field and reveals a significant magnetically induced d...

  9. West nile virus in American white pelican chicks: transmission, immunity, and survival

    Science.gov (United States)

    Sovada, Marsha A.; Pietz, Pamela J.; Hofmeister, Erik K.; Bartos, Alisa J.

    2013-01-01

    West Nile virus (WNV) causes significant mortality of American White Pelican chicks at northern plains colonies. We tested oropharyngeal/cloacal swabs from moribund chicks for shed WNV. Such shedding could enable chick-to-chick transmission and help explain why WNV spreads rapidly in colonies. WNV was detected on swabs from 11% of chicks in 2006 and 52% of chicks in 2007; however, viral titers were low. Before onset of WNV mortality, we tested blood from < 3-week-old chicks for antibodies to WNV; 5% of chicks were seropositive, suggesting passive transfer of maternal antibodies. Among near-fledged chicks, 41% tested positive for anti-WNV antibodies, indicating that they survived infection. Among years and colonies, cumulative incidence of WNV in chicks varied from 28% to 81%, whereas the proportion of chicks surviving WNV (i.e., seropositive) was 64–75%. Our data revealed that WNV kills chicks that likely would fledge in the absence of WNV, that infection of chicks is pervasive, and that significant numbers of chicks survive infection.

  10. Effects of self-pulsation on the spray characteristics of gas-liquid swirl coaxial injector

    Science.gov (United States)

    Kang, Zhongtao; Li, Qinglian; Cheng, Peng; Zhang, Xinqiao; Wang, Zhen-guo

    2016-10-01

    To understand the influence of self-pulsation on the spray characteristics of gas-liquid swirl coaxial injector, a back-lighting photography technique has been employed to capture the instantaneous self-pulsated spray and stable spray images with a high speed camera. The diameter and velocity of the droplets in the spray have been characterized with a Dantec Phase Doppler Anemometry (PDA) system. The effects of self-pulsation on the spray pattern, primary breakup, spray angle, diameter and velocity distribution and mass flow rate distribution are analyzed and discussed. The results show that the spray morphology is greatly influenced by self-pulsation. The stable spray has a cone shape, while the self-pulsated spray looks like a Christmas tree. The main difference of these two sprays is the primary breakup. The liquid film of stable spray keeps stable while that of self-pulsated spray oscillates periodically. The film width of self-pulsated spray varies in a large range with 'neck' and 'shoulder' features existing. The liquid film of self-pulsated spray breaks up at the second neck, and then the second shoulder begins to breakup into ligaments. The self-pulsated spray produces droplet clusters periodically, varies horizontal spray width and mass flux periodically. From the point of spatial distribution, self-pulsation is good for the spray, it uniformizes the mass flux along radius and increases the spray angle. However, when self-pulsation occurs, the SMD distribution varies from an inverted V shape to a hollow cone shape, and SMD increases at all the measuring points. Namely, from the point of atomization performance, self-pulsation has negative effects even when the breakup length is smaller. The effects of self-pulsation on the diameter and velocity distributions of the spray are mainly in the center part of the spray. The periphery of stable and self-pulsated spray has similar diameter and velocity distribution.

  11. Integrating toxicity risk in bird eggs and chicks: Using chick down feathers to estimate mercury concentrations in eggs

    Science.gov (United States)

    Ackerman, Joshua T.; Eagles-Smith, Collin A.

    2009-01-01

    The concentration of mercury (Hg) in eggs that causes reduced hatching success is regarded as a critical end point for Hg toxicity in birds. However, incorporating effects of in ovo mercury exposure on chick health and survival could improve risk assessment. We developed equations to predict Hg in eggs using Hg in chick down feathers, and vice versa, by assessing the relationship between Hg in feathers (0.5−32.4 μg g−1 fw) and eggs (0.04−2.79 μg g−1 fww) for three waterbird species in San Francisco Bay, CA. Feather Hg sampled from embryos of pipping eggs was highly correlated with fresh whole-egg Hg (n = 94, r2 = 0.96). Additionally, using an egg microsampling technique, albumen Hg was correlated with feather Hg sampled from chicks in the same nest (n = 28, r2 = 0.79). Down feather Hg in recaptured chicks (≤10 days old) was correlated with down feather Hg at hatching (≤3 days old; n = 88, r2 = 0.74). Our results demonstrate the utility of using down feathers of chicks ≤10 days of age to nonlethally predict Hg in eggs and thus provide the ability to develop exposure thresholds for eggs that incorporate in ovo Hg’s effects on both egg hatchability and subsequent chick mortality.

  12. Effects of zinc and PGE sub 2 on bone metabolism in chick tibia

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.; Pierce, W.M. Jr. (Univ. of Louisville, KY (United States))

    1991-03-15

    The effects of zinc and prostaglandin E{sub 2} (PGE{sub 2}) on bone metabolism were investigated. Tibiae were removed from 19 day chicks and cultured for periods up to 72 hours in a chemically defined medium. Calcium release from tibiae cultured in the presence of 50-100 ug/dl zinc or 10{sup {minus}9}-10{sup {minus}7} M PGE{sub 2} between 24 and 48 hours increased significantly in a concentration dependent fashion. When 100 ug/dl zinc was added with 10{sup {minus}9}-10{sup {minus}7} M PGE{sub 2} to the culture bone, no additive effect was observed. Flurbiprofen decreased calcium release from chick tibiae significantly in the 24-48 hour incubation period in a concentration dependent fashion, suggesting that endogenous PG's have stimulatory effect on bone calcium release. When 10{sup {minus}6} M flurbiprofen was added with 25-100 ug/dl zinc, the calcium release from tibiae was not changed significantly. Bone release from tibiae was not changed significantly. Bone alkaline phosphatase activity was elevated by 50-100 ug/dl zinc. Addition of PGE{sub 2} did not increase the zinc stimulated elevation of alkaline phosphatase activity. The authors propose the following: zinc stimulates bone cell proliferation; PGE{sub 2} stimulates calcium release from the limited number of osteoclasts in cultured embryonic tibiae; and most bone organ culture system are models of zinc deficiency, since incubation of physiological concentrations of zinc has significant effect.

  13. Pulsating combustion - Combustion characteristics and reduction of emissions

    Energy Technology Data Exchange (ETDEWEB)

    Lindholm, Annika

    1999-11-01

    In the search for high efficiency combustion systems pulsating combustion has been identified as one of the technologies that potentially can meet the objectives of clean combustion and good fuel economy. Pulsating combustion offers low emissions of pollutants, high heat transfer and efficient combustion. Although it is an old technology, the interest in pulsating combustion has been renewed in recent years, due to its unique features. Various applications of pulsating combustion can be found, mainly as drying and heating devices, of which the latter also have had commercial success. It is, however, in the design process of a pulse combustor, difficult to predict the operating frequency, the heat release etc., due to the lack of a well founded theory of the phenomenon. Research concerning control over the combustion process is essential for developing high efficiency pulse combustors with low emissions. Natural gas fired Helmholtz type pulse combustors have been the experimental objects of this study. In order to investigate the interaction between the fluid dynamics and the chemistry in pulse combustors, laser based measuring techniques as well as other conventional measuring techniques have been used. The experimental results shows the possibilities to control the combustion characteristics of pulsating combustion. It is shown that the time scales in the large vortices created at the inlet to the combustion chamber are very important for the operation of the pulse combustor. By increasing/decreasing the time scale for the large scale mixing the timing of the heat release is changed and the operating characteristics of the pulse combustor changes. Three different means for NO{sub x} reduction in Helmholtz type pulse combustors have been investigated. These include exhaust gas recirculation, alteration of air/fuel ratio and changed inlet geometry in the combustion chamber. All used methods achieved less than 10 ppm NO{sub x} emitted (referred to stoichiometric

  14. Features of Pc5 pulsations in the geomagnetic field, auroral luminosity, and Riometer absorption

    Science.gov (United States)

    Belakhovsky, V. B.; Pilipenko, V. A.; Samsonov, S. N.; Lorentsen, D.

    2016-01-01

    Simultaneous morning Pc5 pulsations ( f ~ 3-5 mHz) in the geomagnetic field, aurora intensities (in the 557.7 and 630.0 nm oxygen emissions and the 471.0 nm nitrogen emission), and riometer absorption, were studied based on the CARISMA, CANMOS, and NORSTAR network data for the event of January 1, 2000. According to the GOES-8 satellite observations, these Pc5 geomagnetic pulsations are observed as incompressible Alfvén waves with toroidal polarization in the magnetosphere. Although the Pc5 pulsation frequencies in auroras, the geomagnetic field, and riometer absorption are close to one another, stable phase relationships are not observed between them. Far from all trains of geomagnetic Pc5 pulsations are accompanied by corresponding auroral pulsations; consequently, geomagnetic pulsations are primary with respect to auroral pulsations. Both geomagnetic and auroral pulsations propagate poleward, and the frequency decreases with increasing geomagnetic latitude. When auroral Pc5 pulsations appear, the ratio of the 557.7/630.0 nm emission intensity sharply increases, which indicates that auroral pulsations result from not simply modulated particle precipitation but also an additional periodic acceleration of auroral electrons by the wave field. A high correlation is not observed between Pc5 pulsations in auroras and the riometer absorption, which indicates that these pulsations have a common source but different generation mechanisms. Auroral luminosity modulation is supposedly related to the interaction between Alfvén waves and the region with the field-aligned potential drop above the auroral ionosphere, and riometer absorption modulation is caused by the scattering of energetic electrons by VLF noise pulsations.

  15. Embryonic and neonatal mortality from salmonellosis in captive bred raptors.

    Science.gov (United States)

    Battisti, A; Di Guardo, G; Agrimi, U; Bozzano, A I

    1998-01-01

    In a captive breeding center near Rome (Italy), cases of embryonic and neonatal death were recorded during the breeding seasons in the European eagle owl (Bubo bubo), peregrine falcon (Falco peregrinus), buzzard (Buteo buteo), and lanner falcon. (Falco biarmicus). Salmonella havana and S. virchow were isolated. Three pulli, clinically infected with S. havana, were successfully treated with enrofloxacin. From two groups of healthy 3- to 4-wk-old eagle owls, Salmonella sp. group 61 (61:r:-) and S. havana were collected. A strain of S. paratyphi B was detected in a pharyngeal swab and a fecal sample from an adult female goshawk (Accipiter gentilis), affected with pharyngeal trichomoniasis. A S. hadar strain was collected from a healthy 1-yr-old female eagle owl and S. livingstone was isolated from a 1-mo-old female peregrine, dead of an acute respiratory syndrome. Lesions of fibrinous polyserositis and multivisceral congestion were observed. From frozen 1-day-old chicks, on which adult and young raptors were fed, S. havana and S. livingstone isolates with similar biochemical and drug susceptibility patterns to those isolated from raptors were identified. A surveillance program on infectious diseases reduced embryonic and neonatal death rates in the following breeding seasons.

  16. On the optical pulsations from the Geminga pulsar

    CERN Document Server

    Gil, J; Melikidze, G I; Gil, Janusz; Khechinashvili, David; Melikidze, George

    2000-01-01

    We present a model for generation mechanisms of the optical pulsations recently detected from the Geminga pulsar. We argue that this is just a synchrotron radiation emitted along open magnetic field lines at altitudes of a few light cylinder radii (which requires that Geminga is an almost aligned rotator), where charged particles acquire non-zero pitch-angles as a result of the cyclotron absorption of radio waves in the magnetized pair plasma. This explains self-consistently both the lack of apparent radio emission, at least at frequencies higher than about 100 MHz, and the optical pulsations from the Geminga pulsar. From our model it follows that the synchrotron radiation is a maximum in the infrared band, which suggests that Geminga should also be a source of a pulsed infrared emission.

  17. Experimental investigation on a pulsating heat pipe with hydrogen

    Science.gov (United States)

    Deng, H. R.; Liu, Y. M.; Ma, R. F.; Han, D. Y.; Gan, Z. H.; Pfotenhauer, J. M.

    2015-12-01

    The pulsating heat pipe (PHP) has been increasingly studied in cryogenic application, for its high transfer coefficient and quick response. Compared with Nb3Sn and NbTi, MgB2 whose critical transformation temperature is 39 K, is expected to replace some high-temperature superconducting materials at 25 K. In order to cool MgB2, this paper designs a Hydrogen Pulsating Heat Pipe, which allows a study of applied heat, filling ratio, turn number, inclination angle and length of adiabatic section on the thermal performance of the PHP. The thermal performance of the hydrogen PHP is investigated for filling ratios of 35%, 51%, 70% at different heat inputs, and provides information regarding the starting process is received at three filling ratios.

  18. The First Six Outbursting Cool DA White Dwarf Pulsators

    CERN Document Server

    Bell, Keaton J; Montgomery, M H; Winget, D E; Fusillo, N P Gentile; Raddi, R; Gänsicke, B T

    2016-01-01

    Extensive observations from the Kepler spacecraft have recently revealed a new outburst phenomenon operating in cool pulsating DA (hydrogen atmosphere) white dwarfs (DAVs). With the introduction of two new outbursting DAVs from K2 Fields 7 (EPIC 229228364) and 8 (EPIC 220453225) in these proceedings, we presently know of six total members of this class of object. We present the observational commonalities of the outbursting DAVs: (1) outbursts that increase the mean stellar flux by up to 15%, last many hours, and recur irregularly on timescales of days; (2) effective temperatures that locate them near the cool edge of the DAV instability strip; and (3) rich pulsation spectra with modes that are observed to wander in amplitude/frequency.

  19. Experimental research on heat transfer of pulsating heat pipe

    Institute of Scientific and Technical Information of China (English)

    LI Jia; Yan Li

    2008-01-01

    Experimental research was conducted to understand heat transfer characteristic of pulsating heat pipe in this paper,and the PHP is made of high quality glass capillary tube. Under different fill ratio, heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage. The effects of heating position on heat transfer were discussed. The experimental results indicate that no annular flow appears in top heating condition. Under different fill ratios and heat transfer rate, the flow pattern in PHP is transferred from bulk flow to semi-annular flow and annular flow, and the performance of heat transfer is improved for down heating case. The experimental results indicate that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%. But for pulsating heat pipe with changing diameters the thermal resistance is higher than that with uniform diameters.

  20. Quantitative results of stellar evolution and pulsation theories.

    Science.gov (United States)

    Fricke, K.; Stobie, R. S.; Strittmatter, P. A.

    1971-01-01

    The discrepancy between the masses of Cepheid variables deduced from evolution theory and pulsation theory is examined. The effect of input physics on evolutionary tracks is first discussed; in particular, changes in the opacity are considered. The sensitivity of pulsation masses to opacity changes and to the ascribed values of luminosity and effective temperature are then analyzed. The Cepheid mass discrepancy is discussed in the light of the results already obtained. Other astronomical evidence, including the mass-luminosity relation for main sequence stars, the solar neutrino flux, and cluster ages are also considered in an attempt to determine the most likely source of error in the event that substantial mass loss has not occurred.

  1. Pulsations and outbursts in Be stars: Small differences - big impacts

    CERN Document Server

    Baade, D; Pigulski, A; Carciofi, A; Handler, G; Kuschnig, R; Martayan, Ch; Mehner, A; Moffat, A F J; Pablo, H; Popowicz, A; Rucinski, S M; Wade, G A; Weiss, W W; Zwintz, K

    2016-01-01

    New high-cadence observations with BRITE covering many months confirm that coupled pairs of nonradial pulsation modes are widespread among early-type Be stars. With the difference frequency between the parental variations they may form a roughly sinusoidal variability or the amplitude may cyclicly vary. A first - amplified - beat pattern is also found. In all three cases the amplitudes of difference frequencies can exceed the amplitude sum of the base frequencies, and modulations of the star-to-circumstellar-disk mass-transfer rate may be associated with these slow variations. This suggests more strongly than any earlier observations that significant dissipation of pulsational energy in the atmosphere may be a cause of mass ejections from Be stars. A unifying interpretative concept is presented.

  2. Study of the Thermal Pulsation of AGB Stars

    CERN Document Server

    Halabi, Ghina M

    2014-01-01

    A systematic investigation on the third dredge up in a 3M$_{\\odot}$, solar metallicity AGB star will be presented. The model evolves from the main sequence up to the Asymptotic Giant Branch (AGB). Intermediate mass stars are important because they contribute significantly via the slow neutron capture nucleosynthesis. The aim of this work is to gain insight on the behaviour of the AGB star during thermal pulsation. This investigation is based on an extended numerical simulation of the evolutionary phases and full, consistent AGB model calculations. In particular, the convective structure during pulsation will be studied, giving particular emphasis to the analysis of the stability of the Schwarzschild boundary that will eventually determine the occurrence of Third Dredge Up (hereafter referred to as TDUP). We provide a brief description of our updated evolutionary code and focus primarily on the obtaining the TDUP after 14 thermal pulses. We elaborate on the non-standard treatment of convection known as "oversh...

  3. Pulsating laminar pipe flows with sinusoidal mass flux variations

    Science.gov (United States)

    Ünsal, B.; Ray, S.; Durst, F.; Ertunç, Ö.

    2005-11-01

    Combined analytical and experimental investigation of sinusoidal mass flow-controlled, pulsating, laminar and fully developed pipe flow was carried out. The experimental investigation employed a mass flow control unit built at LSTM-Erlangen for the present investigation. For the analytical investigation, the equations describing such flows were normalized to allow for a general solution, depending only on the normalized amplitude mA* of the mass flow pulsation and the normalized frequency F. The analytical and experimental results are presented in this normalized way and it is shown that good agreement between the results of the authors is obtained. A diagram is presented for the condition of flow reversal in terms of the dimensionless frequency F and the mass flow rate amplitude mA*.

  4. Quasi-periodic pulsations in partially occulted flares

    Science.gov (United States)

    Szaforz, Zaneta; Tomczak, Michal

    The model of oscillating magnetic traps (OMT) suggests that the cusp-like magnetic structures located in an upper part of flare loops are responsible for quasi-periodic pulsations (QPP) observed sometimes in hard X-rays (HXR). Electrons within these oscillating traps are efficiently accelerated and confined, therefore the traps should be recognize as loop-top HXR sources. However, these sources are difficult for reconstruction in the presence of the stronger footpoint HXR sources. To overcome this problem, we analyzed partially occulted flares, observed by Yohkoh, from the survey of Tomczak (2009). We will present the correlation between the diameter of the loop-top HXR source and the period of pulsations. We will present also some interesting examples of observations, for which changes in QPPs coincide with the changes in appearance of loop-top sources.

  5. Modelling hybrid Beta Cephei/SPB pulsations: Gamma Pegasi

    CERN Document Server

    Zdravkov, T

    2009-01-01

    Recent photometric and spectroscopic observations of the hybrid variable Gamma Pegasi (Handler et al. 2009, Handler 2009) revealed 6 frequencies of the SPB type and 8 of the Beta Cep type pulsations. Standard seismic models, which have been constructed with OPAL (Iglesias & Rogers 1996) and OP (Seaton 2005) opacities by fitting three frequencies (those of the radial fundamental and two dipole modes), do not reproduce the frequency range of observed pulsations and do not fit the observed individual frequencies with a satisfactory accuracy. We argue that better fitting can be achieved with opacity enhancements, over the OP data, by about 20-50 percent around the opacity bumps produced by excited ions of the iron-group elements at temperatures of about 200 000 K (Z bump) and 2 million K (Deep Opacity Bump).

  6. Detour behaviour, imprinting and visual lateralization in the domestic chick.

    Science.gov (United States)

    Vallortigara, G; Regolin, L; Pagni, P

    1999-01-01

    Detour behaviour was studied in chicks faced with a vertical-bar barrier behind where an imprinting object (a red ball) was located. Right-eyed chicks took less time to detour the barrier than left-eyed chicks, and binocular chicks showed a bias to detour the barrier on the left side, thus maintaining visual contact with the imprinting object using the lateral field of the right eye, while circling around the barrier. In males, the asymmetries were consistent all along the first two weeks of life, whereas in females they disappeared on days 8 and 11. When tested with a slightly novel version of the original imprinting object (i.e., a ball of a different color), binocular chicks showed a bias to detour the barrier on the right side, thus showing preferential use of the left eye. The same bias occurred when unfamiliar conspecifics were used as goal-objects. Results suggest that cerebral lateralization in birds can directly affect visually-guided motor responses through selective use of the lateral field of vision of the eye contralateral to the hemisphere which has to be put in charge of control of overt behaviour. Copyright 1999 Elsevier Science B.V.

  7. Spontaneous generalization of abstract multimodal patterns in young domestic chicks.

    Science.gov (United States)

    Versace, Elisabetta; Spierings, Michelle J; Caffini, Matteo; Ten Cate, Carel; Vallortigara, Giorgio

    2017-05-01

    From the early stages of life, learning the regularities associated with specific objects is crucial for making sense of experiences. Through filial imprinting, young precocial birds quickly learn the features of their social partners by mere exposure. It is not clear though to what extent chicks can extract abstract patterns of the visual and acoustic stimuli present in the imprinting object, and how they combine them. To investigate this issue, we exposed chicks (Gallus gallus) to three days of visual and acoustic imprinting, using either patterns with two identical items or patterns with two different items, presented visually, acoustically or in both modalities. Next, chicks were given a choice between the familiar and the unfamiliar pattern, present in either the multimodal, visual or acoustic modality. The responses to the novel stimuli were affected by their imprinting experience, and the effect was stronger for chicks imprinted with multimodal patterns than for the other groups. Interestingly, males and females adopted a different strategy, with males more attracted by unfamiliar patterns and females more attracted by familiar patterns. Our data show that chicks can generalize abstract patterns by mere exposure through filial imprinting and that multimodal stimulation is more effective than unimodal stimulation for pattern learning.

  8. Hypoxia adaptation and hemoglobin mutation in Tibetan chick embryo

    Institute of Scientific and Technical Information of China (English)

    GOU Xiao; LI Ning; LIAN Linsheng; YAN Dawei; ZHANG Hao; WU Changxin

    2005-01-01

    Tibetan chick lives at high altitudes between 2600 and 4200 m with a high hatchability and low land breeds survive rarely with a hatchability of 3.0% under hypoxia of simulated 4200 m. Under hypoxia of whole 21 d, the hatchability of Tibetan chick and Recessive White Feather broiler differed with a greatest disparity from day 4 to 11 and also significantly in other stages except from day 1 to 3. Hypoxia in each stage did not reduce significantly survival rate of this stage except hatchability. These two results indicated that the hypoxia in the early stage had an adverse effect on the later stage. All exons encoding chick hemoglobins were sequenced to analyze gene polymorphism. The functional mutation Met-32(B13)-Leu, related with hypoxia, was found in αD globin chain and the mutation frequency increased with increased altitude. In addition, under hypoxic conditions, the population with higher mutation frequency had a higher hatchability. The automated homology model building was carried out using crystal structure coordinates of chick HbD. The results indicated that the substitution Met-32(B13)-Leu provides a more hydrophobic environment which leads to higher stability of heme and oxygen affinity of hemoglobin. The occurrence of the mutation Met-32(B13)-Leu is related to the origin of Tibetan chick.

  9. Pharmacokinetics of paracetamol in chicks treated with metronidazole

    Directory of Open Access Journals (Sweden)

    S.M. Hussain

    2017-06-01

    Full Text Available Effect of metronidazole on the pharmacokinetics of paracetamol were examined in chicks. Chicks were dosed orally with metronidazole at 350 mg\\kg of body weight daily (10 -13 days of age. On the last day of metronidazole dosing, chicks injected intraperitoneally with paracetamol at of 50 mg\\kg of body weight. Paracetamol appeared in chick plasma at 52.00, 45.00, 40.75, 32.75, 23.25 µg \\ml after 0.25, 0.50, 0.75, 1, 2, 4 hours of injection respectively. A significantly decreased the concentration paracetamol at times of 0.25, 0.50, 0.75, 1, 4 hours post injection and appeared at concentrations of 36.62, 35.37, 25.62, 20.50, 11.00 µg\\ml. These was reflected by changes in the pharmacokinetics of paracetamol as show by the increase elimination rate constant (48% and decrease in the half-life (32 % and increase in volume distribution (29% and increase in clearance by (96% and decrease in the area under the plasma curve (33% and decrease in the area under moment curve 65% and lack mean residence time (33%. These results indicate that oral dosing of chicks with metronidazole for four consecutive days and this effect increase in the elemination rate of paracetamol and this effect must be considered when therapy with paracetamol when given during metronidazole therapy.

  10. Modeling chick to assess diabetes pathogenesis and treatment.

    Science.gov (United States)

    Datar, Savita P; Bhonde, Ramesh R

    2011-01-01

    Animal models have been used extensively in diabetes research. Studies on animal models have contributed to the discovery and purification of insulin, development of new therapeutic approaches, and progress in fundamental and clinical research. However, conventional rodent and large animal mammalian models face ethical, practical, or technical limitations. Therefore, it would be beneficial developing an alternative model for diabetes research which would overcome these limitations. Amongst other vertebrates, birds are phylogenically closer to mammals, and amongst birds, the chick has been used as one of the favored models in developmental biology, toxicology, cancer research, immunology, and drug testing. Chicken eggs are readily available, have a short incubation period and easily accessible embryos. Based on these inimitable advantages, the present review article aims to discuss the suitability of the chick as a model system to study specific aspects of diabetes. The review focuses on the application of i) chick pancreatic islets for screening of antidiabetic agents and for islet banking, (ii) shell-less chick embryo culture as a model to study hyperglycemia-induced malformations observed in mammalian embryos, and (iii) chick chorioallantoic membrane (CAM) to examine glucose-induced endothelial damage leading to inhibition of angiogenesis. Copyright © by Lab & Life Press/SBDR

  11. Cognitive bias in the chick anxiety-depression model.

    Science.gov (United States)

    Salmeto, Amy L; Hymel, Kristen A; Carpenter, Erika C; Brilot, Ben O; Bateson, Melissa; Sufka, Kenneth J

    2011-02-10

    Cognitive bias is a phenomenon that presents in clinical populations where anxious individuals tend to adopt a more pessimistic-like interpretation of ambiguous aversive stimuli whereas depressed individuals tend to adopt a less optimistic-like interpretation of ambiguous appetitive stimuli. To further validate the chick anxiety-depression model as a neuropsychiatric simulation we sought to quantify this cognitive endophenotype. Chicks exposed to an isolation stressor of 5m to induce an anxiety-like or 60 m to induce a depressive-like state were then tested in a straight alley maze to a series of morphed ambiguous appetitive (chick silhouette) to aversive (owl silhouette) cues. In non-isolated controls, runway start and goal latencies generally increased as a function of greater amounts of aversive characteristics in the cues. In chicks in the anxiety-like state, runway latencies were increased to aversive ambiguous cues, reflecting more pessimistic-like behavior. In chicks in the depression-like state, runway latencies were increased to both aversive and appetitive ambiguous cues, reflecting more pessimistic-like and less optimistic-like behavior, respectively.

  12. Decreasing of pulsation intensity levels in X-ray receivers

    CERN Document Server

    Dvoryankin, V F; Kudryashov, A A; Petrov, A G

    2002-01-01

    The low frequency filter is applied in the multichannel receiver on the basis of the GaAs epitaxial structures for decreasing the pulsations level at the signals amplifier outlet. The optimal band of the filter is determined by the transition processes by the detector scanning in the roentgen beams. The X-ray source of radiation with the medium-frequency feeding generator is used for verifying the quality of the obtained X-ray image

  13. A size limit for uniformly pulsating sources of electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Dewdney, A.K.

    1979-01-01

    An extremal model for a uniformly pulsating source of electromagnetic radiation is developed, and a formula is obtained which relates the source variation to diameter, pulse width, and period. An upper limit on source diameter is derived from this formula, applied to three pulsars, and compared with standard estimates of their diameters. The use of the limit formula is shown to be no less justified, in general, than the size estimate based on the product of variation period and the speed of light.

  14. Effect of orientation on heat transfer in pulsating heat pipe

    Directory of Open Access Journals (Sweden)

    Naumova A. M.

    2010-10-01

    Full Text Available The paper presents the results of experimental research of orientation effect on heat transfer characteristics of a pulsating heat pipe (PHP. It is shown that transport of either mass or heat depends on PHP orientation against it`s axis. As a consequence of comparing experimental data with other authors’ results it was concluded that PHP thermal resistance depends not only on orientation but on some other determinal factors such as device construction and thermophysical properties of heat carrier.

  15. Research of heat exchange rate of the pulsating heat pipe

    Directory of Open Access Journals (Sweden)

    Kravets V. Yu.

    2010-02-01

    Full Text Available Given article presents experimental research of heat transfer characteristics of the pulsating heat pipe (PHP which consists of seven coils with 1 mm inner diameter. Water was used as the heat carrier. PHP construction, measuring circuit and research technique are presented. It is shown that under PHP functioning there are two characteristic modes of operation, which can be distinguished by values of thermal resistance. PHP heat exchange features are disclosed.

  16. Diffusion and pulsations in slowly rotating B stars

    CERN Document Server

    Turcotte, S

    2005-01-01

    Diffusion in cool B stars of the main sequence has been shown to strongly affect opacities and convection in cool B stars of the main sequence. We show here that diffusion in B stars maintains or enhances the excitation of pulsations in these stars. This result conflicts with observations as cool B stars that show evidence of diffusion, the HgMn stars, are stable to the current detection level. We discuss possible implications of this discrepancy for the models.

  17. Effects of Uniform and Differential Rotation on Stellar Pulsations

    OpenAIRE

    Lovekin, C. C.; Deupree, R. G.; Clement, M.J.

    2008-01-01

    We have investigated the effects of uniform rotation and a specific model for differential rotation on the pulsation frequencies of 10 \\Msun\\ stellar models. Uniform rotation decreases the frequencies for all modes. Differential rotation does not appear to have a significant effect on the frequencies, except for the most extreme differentially rotating models. In all cases, the large and small separations show the effects of rotation at lower velocities than do the individual frequencies. Unf...

  18. Self-pulsation threshold of Raman amplified Brillouin fiber cavities.

    Science.gov (United States)

    Ott, J R; Pedersen, M E V; Rottwitt, K

    2009-08-31

    An implicit equation for the oscillation threshold of stimulated Brillouin scattering from Raman amplified signals in fibers with external feedback is derived under the assumption of no depletion. This is compared to numerical investigations of Raman amplification schemes showing good agreement for high reflectivities. For low reflectivities and high attenuation or long fibers, the assumption of no depletion is shown not to be valid. In these cases the effects of the depletion on the self-pulsation is examined.

  19. Self-pulsation threshold of Raman amplified Brillouin fiber cavities

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær; Pedersen, Martin Erland Vestergaard; Rottwitt, Karsten

    2009-01-01

    An implicit equation for the oscillation threshold of stimulated Brillouin scattering from Raman amplified signals in fibers with external feedback is derived under the assumption of no depletion. This is compared to numerical investigations of Raman amplification schemes showing good agreement...... for high reflectivities. For low reflectivities and high attenuation or long fibers, the assumption of no depletion is shown not to be valid. In these cases the effects of the depletion on the self-pulsation is examined....

  20. Analysis of retinal cell development in chick embryo by immunohistochemistry and in ovo electroporation techniques

    Directory of Open Access Journals (Sweden)

    Pashkova Anna

    2010-01-01

    Full Text Available Abstract Background Retinal cell development has been extensively investigated; however, the current knowledge of dynamic morphological and molecular changes is not yet complete. Results This study was aimed at revealing the dynamic morphological and molecular changes in retinal cell development during the embryonic stages using a new method of targeted retinal injection, in ovo electroporation, and immunohistochemistry techniques. A plasmid DNA that expresses the green fluorescent protein (GFP as a marker was delivered into the sub-retinal space to transfect the chick retinal stem/progenitor cells at embryonic day 3 (E3 or E4 with the aid of pulses of electric current. The transfected retinal tissues were analyzed at various stages during chick development from near the start of neurogenesis at E4 to near the end of neurogenesis at E18. The expression of GFP allowed for clear visualization of cell morphologies and retinal laminar locations for the indication of retinal cell identity. Immunohistochemistry using cell type-specific markers (e.g., Visinin, Xap-1, Lim1+2, Pkcα, NeuN, Pax6, Brn3a, Vimentin, etc. allowed further confirmation of retinal cell types. The composition of retinal cell types was then determined over time by counting the number of GFP-expressing cells observed with morphological characteristics specific to the various retinal cell types. Conclusion The new method of retinal injection and electroporation at E3 - E4 allows the visualization of all retinal cell types, including the late-born neurons, e.g., bipolar cells at a level of single cells, which has been difficult with a conventional method with injection and electroporation at E1.5. Based on data collected from analyses of cell morphology, laminar locations in the retina, immunohistochemistry, and cell counts of GFP-expressing cells, the time-line and dynamic morphological and molecular changes of retinal cell development were determined. These data provide more

  1. Intermediate frequency magnetic field and chick embryotoxicity.

    Science.gov (United States)

    Nishimura, Izumi; Tanaka, Keiko; Negishi, Tadashi

    2013-09-01

    Intermediate frequency magnetic fields (MFs) have widely been used in industrial machines and home appliances, such as induction heating cookers, although toxicity studies to evaluate the potential health risks of such fields are insufficient. In induction heating cookers, the MF source (i.e. hobs), is located near the abdominal position of a person cooking. Hence, developmental effects on the fetus may be a concern in case the person is a pregnant woman. Fertile White Leghorn eggs (60/group) were either exposed to 20 kHz, 1.1 mT(rms) or 60 kHz, 0.11 mT(rms) sinusoidal MFs for 19 days during embryogenesis. The same number of eggs served as a control group. In addition, a sham-sham experiment was conducted to validate the equality between exposure and control facilities. After exposure, embryos were examined for mortality rate and stage. Live embryos were evaluated for developmental stage and gross and skeletal anomalies. Length of upper beak and leg digits was also measured. Examinations were conducted in a blinded fashion to ensure quality assurance; experiments were triplicated for each frequency to confirm the outcome reproducibility. Mortality rate and stage, incidence of malformed embryos, and developmental variables in live embryos were found to be similar between the MF-exposed and corresponding control group. Incidence of gross anomalies such as mandibular edema and skeletal anomalies such as coccyx defects were low across the experiments, and no significant group differences were noted. In conclusion, exposure to 20 kHz or 60 kHz MF did not produce any significant teratogenic developmental effects in chick embryos.

  2. Asteroseismology of hybrid $\\delta$ Scuti--$\\gamma$ Doradus pulsating stars

    CERN Document Server

    Arias, J P Sánchez; Althaus, L G

    2016-01-01

    Hybrid $\\delta$ Scuti-$\\gamma$ Doradus pulsating stars show acoustic ($p$) oscillation modes typical of $\\delta$ Scuti variable stars, and gravity ($g$) pulsation modes characteristic of $\\gamma$ Doradus variable stars simultaneously excited. Observations from space missions like MOST, CoRoT, and \\emph{Kepler} have revealed a large number of hybrid $\\delta$ Scuti-$\\gamma$ Doradus pulsators, thus paving the way for a exciting new channel for asteroseismic studies. We perform a detailed asteroseismological modeling of five hybrid $\\delta$ Scuti-$\\gamma$ Doradus stars. We employ a grid-based modeling approach to sound the internal structure of the target stars by employing a huge grid of stellar models from the zero-age main sequence to the terminal-age main sequence, varying parameters like stellar mass, effective temperature, metallicity and core overshooting. We compute their adiabatic radial ($\\ell= 0$) and non-radial ($\\ell= 1, 2, 3$) $p$ and $g$ mode periods. We employ two model-fitting procedures to searc...

  3. THE PULSATION MODE AND DISTANCE OF THE CEPHEID FF AQUILAE

    Energy Technology Data Exchange (ETDEWEB)

    Turner, D. G. [Department of Astronomy and Physics, Saint Mary' s University, Halifax, NS B3H 3C3 (Canada); Kovtyukh, V. V. [Astronomical Observatory, Odessa National University, and Isaac Newton Institute of Chile, Odessa Branch, T. G. Shevkenko Park, 65014 Odessa (Ukraine); Luck, R. E. [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7215 (United States); Berdnikov, L. N., E-mail: turner@ap.smu.ca, E-mail: val@deneb1.odessa.ua, E-mail: rel2@case.edu, E-mail: leonid.berdnikov@gmail.com [Sternberg Astronomical Institute, Moscow M. V. Lomonosov State University, Moscow 119992 (Russian Federation)

    2013-07-20

    The determination of pulsation mode and distance for field Cepheids is a complicated problem best resolved by a luminosity estimate. For illustration a technique based on spectroscopic luminosity discrimination is applied to the 4.47 day s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable yield values of (M{sub V} ) = -3.40 {+-} 0.02 s.e. ({+-}0.04 s.d.), average effective temperature T{sub eff} = 6195 {+-} 24 K, and intrinsic color ((B) - (V)){sub 0} = +0.506 {+-} 0.007, corresponding to a reddening of E{sub B-V} = 0.25 {+-} 0.01, or E{sub B-V}(B0) = 0.26 {+-} 0.01. The skewed light curve, intrinsic color, and luminosity of FF Aql are consistent with fundamental mode pulsation for a small-amplitude classical Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A distance of 413 {+-} 14 pc is estimated from the Cepheid's angular diameter in conjunction with a mean radius of (R) = 39.0 {+-} 0.7 R{sub Sun} inferred from its luminosity and effective temperature. The dust extinction toward FF Aql is described by a ratio of total-to-selective extinction of R{sub V} = A{sub V} /E(B - V) = 3.16 {+-} 0.34 according to the star's apparent distance modulus.

  4. Development of a balloon volume sensor for pulsating balloon catheters.

    Science.gov (United States)

    Nolan, Timothy D C; Hattler, Brack G; Federspiel, William J

    2004-01-01

    Helium pulsed balloons are integral components of several cardiovascular devices, including intraaortic balloon pumps (IABP) and a novel intravenous respiratory support catheter. Effective use of these devices clinically requires full inflation and deflation of the balloon, and improper operating conditions that lead to balloon under-inflation can potentially reduce respiratory or cardiac support provided to the patient. The goal of the present study was to extend basic spirographic techniques to develop a system to dynamically measure balloon volumes suitable for use in rapidly pulsating balloon catheters. The dynamic balloon volume sensor system (DBVSS) developed here used hot wire anemometry to measure helium flow in the drive line from console to catheter and integrated the flow to determine the volume delivered in each balloon pulsation. An important component of the DBVSS was an algorithm to automatically detect and adjust flow signals and measured balloon volumes in the presence of gas composition changes that arise from helium leaks occurring in these systems. The DBVSS was capable of measuring balloon volumes within 5-10% of actual balloon volumes over a broad range of operating conditions relevant to IABP and the respiratory support catheter. This includes variations in helium concentration from 70-100%, pulsation frequencies from 120-480 beats per minute, and simulated clinical conditions of reduced balloon filling caused by constricted vessels, increased driveline, or catheter resistance.

  5. Constraining the neutrino magnetic dipole moment from white dwarf pulsations

    CERN Document Server

    Córsico, Alejandro H; Bertolami, Marcelo M Miller; Kepler, S O; García-Berro, Enrique

    2014-01-01

    Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to search for additional sources of cooling due to the emission of axions, neutralinos, or neutrinos with magnetic dipole moment. In this work, we derive an upper bound to the neutrino magnetic dipole moment using an estimate of the rate of period change of the pulsating DB white dwarf star PG 1351+489. By comparing the theoretical rate of change of period expected for this star with the rate of change of period with time of PG 1351+489, we assess the possible existence of additional cooling by neutrinos with magnetic dipole moment. Our models suggest the existence of some additional cooling in this pulsating DB white dwarf, consistent with a non-zero magnetic dipole moment. Our upper limit for the neutrino magnetic dipole moment is somewhat less restrictive than, but still compat...

  6. Studies of the Long Secondary Periods in Pulsating Red Giants

    Science.gov (United States)

    Percy, J. R.; Deibert, E.

    2016-12-01

    We have used systematic, sustained visual observations from the AAVSO International Database and the AAVSO time-series analysis package VSTAR to study the unexplained "long secondary periods" (LSPs) in 27 pulsating red giants. In our sample, the LSPs range from 479 to 2967 days, and are on average 8.1 +/- 1.3 times the excited pulsation period. There is no evidence for more than one LSP in each star. In stars with both the fundamental and first overtone radial period present, the LSP is more often about 10 times the latter. The visual amplitudes of the LSPs are typically 0.1 magnitude and do not correlate with the LSP. The phase curves tend to be sinusoidal, but at least two are sawtooth. The LSPs are stable, within their errors, over the timespan of our data, which is typically 25,000 days. The amplitudes, however, vary by up to a factor of two or more on a time scale of roughly 20-30 LSPs. There is no obvious difference between the carbon (C) stars and the normal oxygen (M) stars. Previous multicolor observations showed that the LSP color variations are similar to those of the pulsation period, and of the LSPs in the Magellanic Clouds, and not like those of eclipsing stars. We note that the LSPs are similar to the estimated rotation periods of the stars, though the latter have large uncertainties. This suggests that the LSP phenomenon may be a form of modulated rotational variability.

  7. Mass-spring model of a self-pulsating drop.

    Science.gov (United States)

    Antoine, Charles; Pimienta, Véronique

    2013-12-03

    Self-pulsating sessile drops are a striking example of the richness of far-from-equilibrium liquid/liquid systems. The complex dynamics of such systems is still not fully understood, and simple models are required to grasp the mechanisms at stake. In this article, we present a simple mass-spring mechanical model of the highly regular drop pulsations observed in Pimienta, V.; Brost, M.; Kovalchuk, N.; Bresch, S.; Steinbock, O. Complex shapes and dynamics of dissolving drops of dichloromethane. Angew. Chem., Int. Ed. 2011, 50, 10728-10731. We introduce an effective time-dependent spreading coefficient that sums up all of the forces (due to evaporation, solubilization, surfactant transfer, coffee ring effect, solutal and thermal Marangoni flows, drop elasticity, etc.) that pull or push the edge of a dichloromethane liquid lens, and we show how to account for the periodic rim breakup. The model is examined and compared against experimental observations. The spreading parts of the pulsations are very rapid and cannot be explained by a constant positive spreading coefficient or superspreading.

  8. Pulsations powered by hydrogen shell burning in white dwarfs

    CERN Document Server

    Camisassa, María E; Althaus, Leandro G; Shibahashi, Hiromoto

    2016-01-01

    In the absence of a third dredge-up episode during the asymptotic giant branch phase, white dwarf models evolved from low-metallicity progenitors have a thick hydrogen envelope, which makes hydrogen shell burning be the most important energy source. We investigate the pulsational stability of white dwarf models with thick envelopes to see whether nonradial $g$-mode pulsations are triggered by hydrogen burning, with the aim of placing constraints on hydrogen shell burning in cool white dwarfs and on a third dredge-up during the asymptotic giant branch evolution of their progenitor stars. We construct white-dwarf sequences from low-metallicity progenitors by means of full evolutionary calculations, and analyze their pulsation stability for the models in the range of effective temperatures $T_{\\rm eff} \\sim 15\\,000\\,-\\, 8\\,000$ K. We demonstrate that, for white dwarf models with masses $M_{\\star} \\lesssim 0.71\\,\\rm M_{\\sun}$ and effective temperatures $8\\,500 \\lesssim T_{\\rm eff} \\lesssim 11\\,600$ K that evolved...

  9. CLoNe is a new method to target single progenitors and study their progeny in mouse and chick.

    Science.gov (United States)

    García-Moreno, Fernando; Vasistha, Navneet A; Begbie, Jo; Molnár, Zoltán

    2014-04-01

    Cell lineage analysis enables us to address pivotal questions relating to: the embryonic origin of cells and sibling cell relationships in the adult body; the contribution of progenitors activated after trauma or disease; and the comparison across species in evolutionary biology. To address such fundamental questions, several techniques for clonal labelling have been developed, each with its shortcomings. Here, we report a novel method, CLoNe that is designed to work in all vertebrate species and tissues. CLoNe uses a cocktail of labelling, targeting and transposition vectors that enables targeting of specific subpopulations of progenitor types with a combination of fluorophores resulting in multifluorescence that describes multiple clones per specimen. Furthermore, transposition into the genome ensures the longevity of cell labelling. We demonstrate the robustness of this technique in mouse and chick forebrain development, and show evidence that CLoNe will be broadly applicable to study clonal relationships in different tissues and species.

  10. A new take on an old story: chick limb organ culture for skeletal niche development and regenerative medicine evaluation

    Directory of Open Access Journals (Sweden)

    EL Smith

    2013-09-01

    Full Text Available Scientific research and progress, particularly in the drug discovery and regenerative medicine fields, is typically dependent on suitable animal models to develop new and improved clinical therapies for injuries and diseases. In vivo model systems are frequently utilised, but these models are expensive, highly complex and pose a number of ethical considerations leading to the development and use of a number of alternative ex vivo model systems. The ex vivo embryonic chick long bone and limb bud models have been utilised in the scientific research field as a model to understand skeletal development for over eighty years. The rapid development of avian skeletal tissues, coupled with the ease of experimental manipulation, availability of genome sequence and the presence of multiple cell and tissue types has seen such model systems gain significant research interest in the last few years in the tissue engineering field. The models have been explored both as systems for understanding the developmental bone niche and as potential testing tools for tissue engineering strategies for bone repair and regeneration. This review details the evolution of the chick limb organ culture system and presents recent innovative developments and emerging techniques and technologies applied to these models that are aiding our understanding of skeletal developmental and regenerative medicine research and application.

  11. High Incubation Temperature and Threonine Dietary Level Improve Ileum Response Against Post-Hatch Salmonella Enteritidis Inoculation in Broiler Chicks.

    Science.gov (United States)

    de Barros Moreira Filho, Alexandre Lemos; de Oliveira, Celso José Bruno; de Oliveira, Heraldo Bezerra; Campos, Danila Barreiro; Guerra, Ricardo Romão; Costa, Fernando Guilherme Perazzo; Givisiez, Patricia Emília Naves

    2015-01-01

    This study assessed the effect of both embryonic thermal manipulation and dietary threonine level on the response of broilers inoculated with Salmonella Enteritidis, considering bacterial counts in the cecal contents, intestinal morphology, mucin and heat shock protein 70 gene expression, body weight and weight gain. Thermal manipulation was used from 11 days of incubation until hatch, defining three treatments: standard (37.7°C), continuous high temperature (38.7°C) and continuous low temperature (36.7°C). After hatch, chicks were distributed according to a 3x2+1 factorial arrangement (three temperatures and two threonine levels and one sham-inoculated control). At two days of age, all chicks were inoculated with Salmonella Enteritidis, except for the sham-inoculated control group. There was no interaction between the factors on any analyses. High temperature during incubation was able to reduce colonization by Salmonella Enteritidis in the first days, reducing both Salmonella counts and the number of positive birds. It also increased mucin expression and decreased Hsp70 expression compared with other inoculated groups. High temperature during incubation and high threonine level act independently to reduce the negative effects associated to Salmonella Enteritidis infection on intestinal morphology and performance, with results similar to sham-inoculated birds. The findings open new perspectives for practical strategies towards the pre-harvest Salmonella control in the poultry industry.

  12. High Incubation Temperature and Threonine Dietary Level Improve Ileum Response Against Post-Hatch Salmonella Enteritidis Inoculation in Broiler Chicks.

    Directory of Open Access Journals (Sweden)

    Alexandre Lemos de Barros Moreira Filho

    Full Text Available This study assessed the effect of both embryonic thermal manipulation and dietary threonine level on the response of broilers inoculated with Salmonella Enteritidis, considering bacterial counts in the cecal contents, intestinal morphology, mucin and heat shock protein 70 gene expression, body weight and weight gain. Thermal manipulation was used from 11 days of incubation until hatch, defining three treatments: standard (37.7°C, continuous high temperature (38.7°C and continuous low temperature (36.7°C. After hatch, chicks were distributed according to a 3x2+1 factorial arrangement (three temperatures and two threonine levels and one sham-inoculated control. At two days of age, all chicks were inoculated with Salmonella Enteritidis, except for the sham-inoculated control group. There was no interaction between the factors on any analyses. High temperature during incubation was able to reduce colonization by Salmonella Enteritidis in the first days, reducing both Salmonella counts and the number of positive birds. It also increased mucin expression and decreased Hsp70 expression compared with other inoculated groups. High temperature during incubation and high threonine level act independently to reduce the negative effects associated to Salmonella Enteritidis infection on intestinal morphology and performance, with results similar to sham-inoculated birds. The findings open new perspectives for practical strategies towards the pre-harvest Salmonella control in the poultry industry.

  13. Prenatal music stimulation facilitates the postnatal functional development of the auditory as well as visual system in chicks (Gallus domesticus)

    Indian Academy of Sciences (India)

    Saborni Roy; Tapas C Nag; Ashish Datt Upadhyay; Rashmi Mathur; Suman Jain

    2014-03-01

    Rhythmic sound or music is known to improve cognition in animals and humans. We wanted to evaluate the effects of prenatal repetitive music stimulation on the remodelling of the auditory cortex and visual Wulst in chicks. Fertilized eggs (0 day) of white leghorn chicken (Gallus domesticus) during incubation were exposed either to music or no sound from embryonic day 10 until hatching. Auditory and visual perceptual learning and synaptic plasticity, as evident by synaptophysin and PSD-95 expression, were done at posthatch days (PH) 1, 2 and 3. The number of responders was significantly higher in the music stimulated group as compared to controls at PH1 in both auditory and visual preference tests. The stimulated chicks took significantly lesser time to enter and spent more time in the maternal area in both preference tests. A significantly higher expression of synaptophysin and PSD-95 was observed in the stimulated group in comparison to control at PH1-3 both in the auditory cortex and visual Wulst. A significant inter-hemispheric and gender-based difference in expression was also found in all groups. These results suggest facilitation of postnatal perceptual behaviour and synaptic plasticity in both auditory and visual systems following prenatal stimulation with complex rhythmic music.

  14. Prenatal music stimulation facilitates the postnatal functional development of the auditory as well as visual system in chicks (Gallus domesticus).

    Science.gov (United States)

    Roy, Saborni; Nag, Tapas C; Upadhyay, Ashish Datt; Mathur, Rashmi; Jain, Suman

    2014-03-01

    Rhythmic sound or music is known to improve cognition in animals and humans. We wanted to evaluate the effects of prenatal repetitive music stimulation on the remodelling of the auditory cortex and visual Wulst in chicks. Fertilized eggs (0 day) of white leghorn chicken (Gallus domesticus) during incubation were exposed either to music or no sound from embryonic day 10 until hatching. Auditory and visual perceptual learning and synaptic plasticity, as evident by synaptophysin and PSD-95 expression, were done at posthatch days (PH) 1, 2 and 3. The number of responders was significantly higher in the music stimulated group as compared to controls at PH1 in both auditory and visual preference tests. The stimulated chicks took significantly lesser time to enter and spent more time in the maternal area in both preference tests. A significantly higher expression of synaptophysin and PSD-95 was observed in the stimulated group in comparison to control at PH1-3 both in the auditory cortex and visual Wulst. A significant inter-hemispheric and gender-based difference in expression was also found in all groups. These results suggest facilitation of postnatal perceptual behaviour and synaptic plasticity in both auditory and visual systems following prenatal stimulation with complex rhythmic music.

  15. Mechanical vibrations in the transport of hatching eggs and the losses caused in the hatch and quality of broiler chicks

    Directory of Open Access Journals (Sweden)

    Ana Carolina Donofre

    2017-02-01

    Full Text Available Many factors present in eggs’ transportation from incubator to growing confinements can damage their integrity and, consequently, the results of the incubation. This study aimed to evaluate whether the intensity and duration of exposures of hatching eggs to mechanical vibrations were capable of affecting the hatch and the quality of broiler chicks. Four treatments, determined by two intensities of vibrations and two durations of exposures were evaluated and compared with a control group in a randomised design in blocks with four repetitions. The vibrations were applied by a mechanical shaker before incubation. Then the eggs were incubated and as the following responses were evaluated: hatchability, the type of embryonic mortality, the quality of the birds and the total of losses. The analyses were carried out by a binomial regression model, with application of the Wald test at 5% significance level. The results showed that the exposure of eggs to mechanical vibrations harmfully affects the hatchability and reduces the ratio (percentage of high quality chicks. Highest vibration level together with longer duration of exposure resulted in worst hatchability and losses. It is argued that the mechanical vibrations are potentially damaging and should be regarded as an important factor in the management of hatching eggs.

  16. KIC 3858884: a hybrid {\\delta} Sct pulsator in a highly eccentric eclipsing binary

    CERN Document Server

    Maceroni, C; da Silva, R; Montalbán, J; Lee, C -U; Ak, H; Deshpande, R; Yakut, K; Debosscher, J; Guo, Z; Kim, S -L; Lee, J W; Southworth, J

    2014-01-01

    The analysis of eclipsing binaries containing non-radial pulsators allows: i) to combine two different and independent sources of information on the internal structure and evolutionary status of the components, and ii) to study the effects of tidal forces on pulsations. KIC 3858884 is a bright Kepler target whose light curve shows deep eclipses, complex pulsation patterns with pulsation frequencies typical of {\\delta} Sct, and a highly eccentric orbit. We present the result of the analysis of Kepler photometry and of high resolution phaseresolved spectroscopy. Spectroscopy yielded both the radial velocity curves and, after spectral disentangling, the primary component effective temperature and metallicity, and line-of-sight projected rotational velocities. The Kepler light curve was analyzed with an iterative procedure devised to disentangle eclipses from pulsations which takes into account the visibility of the pulsating star during eclipses. The search for the best set of binary parameters was performed com...

  17. Continuous versus pulsating flow boiling. Experimental comparison, visualization, and statistical analysis

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Meyer, Knud Erik

    2017-01-01

    are reduced from transient measurements immediately downstream of the expansion valves at low vapor qualities. The results show that the pulsations improve the time-averaged heat transfer coefficient by 3.2% on average at low cycle time (1 to 2 s), whereas the pulsations may reduce the time-averaged heat......This experimental study investigates an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The hypothesis is that pulsations increase the flow boiling heat transfer by means of better bulk fluid mixing, increased wall wetting, and flow-regime destabilization....... The fluid pulsations are introduced by a flow modulating expansion device and are compared with continuous flow by a stepper-motor expansion valve in terms of time-averaged heat transfer coefficient. The cycle time ranges from 1 to 9 s for the pulsations. The time-averaged heat transfer coefficients...

  18. Continuous vs. pulsating flow boiling. Part 1: Experimental comparison and visualization

    DEFF Research Database (Denmark)

    Kærn, Martin Ryhl; Elmegaard, Brian; Meyer, Knud Erik

    2016-01-01

    are reduced from transient measurements immediately downstream of the expansion valves at low vapor qualities. The results show that the pulsations improve the time-averaged heat transfer coefficient by 3.2 % on average at low cycle time (1 s to 2) s, whereas the pulsations may reduce the time-averaged heat......This experimental study investigates an active method for flow boiling heat transfer enhancement by means of fluid flow pulsation. The hypothesis is that pulsations increase the flow boiling heat transfer by means of better bulk fluid mixing, increased wall wetting and flow-regime destabilization....... The fluid pulsations are introduced by a flow modulating expansion device and are compared with continuous flow by a stepper-motor expansion valve in terms of time-averaged heat transfer coefficient. The cycle time ranges from 1 s to 9 s for the pulsations. The time-averaged heat transfer coefficients...

  19. A Study on the Influence of Commutation Time on Torque Pulsating in BLDCM

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Choel Ju; Kang, Byoung Hee; Mok, Hyoung Su; Choe, Gyu-Ha [Konkuk University, Seoul(Korea)

    2001-01-01

    A BLDC motor has a serious drawback that torque pulsation is generated in every commutation period though it has many advantages compared to the conventional DC Motor. In this paper, the influence of commutation time on torque pulsation is studied. Generally in calculating the torque of BLDC motor, it is assumed that the decaying phase back EMF is constant, but the torque model considering decaying phase back EMF is introduced here. Through it, the torque in commutation period has torque pulsation component caused by commutation itself and it cannot be removed perfectly even if there is no current and pulsation. To reduce the torque pulsation, a new method is proposed, which controls a point of commutation and the optimal point of commutation is found. Simulation shows proposed method reduces the torque pulsation considerately. (author). 5 refs., 8 figs., 2 tabs.

  20. GW Librae: A unique laboratory for pulsations in an accreting white dwarf

    CERN Document Server

    Toloza, O; Hermes, J J; Townsley, D M; Schreiber, M R; Szkody, P; Pala, A; Beuermann, K; Bildsten, L; Breedt, E; Cook, M; Godon, P; Henden, A A; Hubeny, I; Knigge, C; Long, K S; Marsh, T R; de Martino, D; Mukadam, A S; Myers, G; Nelson, P; Oksanen, A; Patterson, J; Sion, E M; Zorotovic, M

    2016-01-01

    Non-radial pulsations have been identified in a number of accreting white dwarfs in cataclysmic variables. These stars offer insight into the excitation of pulsation modes in atmospheres with mixed compositions of hydrogen, helium, and metals, and the response of these modes to changes in the white dwarf temperature. Among all pulsating cataclysmic variable white dwarfs, GW Librae stands out by having a well-established observational record of three independent pulsation modes that disappeared when the white dwarf temperature rose dramatically following its 2007 accretion outburst. Our analysis of HST ultraviolet spectroscopy taken in 2002, 2010 and 2011, showed that pulsations produce variations in the white dwarf effective temperature as predicted by theory. Additionally in May~2013, we obtained new HST/COS ultraviolet observations that displayed unexpected behaviour: besides showing variability at ~275s, which is close to the post-outburst pulsations detected with HST in 2010 and 2011, the white dwarf exhi...

  1. Changes in free amino acid and monoamine concentrations in the chick brain associated with feeding behavior

    OpenAIRE

    Tran, Phuong V; Chowdhury, Vishwajit S.; Nagasawa, Mao; Furuse, Mitsuhiro

    2015-01-01

    Domesticated chicks are precocial and therefore have relatively well-developed feeding behavior. The role of hypothalamic neuropeptides in food-intake regulation in chicks has been reported for decades. However, we hypothesized that nutrients and their metabolites in the brain may be involved in food intake in chicks because these animals exhibit a very frequent feeding pattern. Therefore, the purpose of this study was to examine the feeding behavior of chicks as well as the associated change...

  2. Causes of mortality of albatross chicks at Midway Atoll

    Science.gov (United States)

    Sileo, L.; Sievert, P.R.; Samuel, M.D.

    1990-01-01

    As part of an investigation of the effect of plastic ingestion on seabirds in Hawaii, we necropsied the carcasses of 137 Laysan albatross (Diomedea immutabilis) chicks from Midway Atoll in the Pacific Ocean during the summer of 1987. Selected tissues were collected for microbiological, parasitological, toxicological or histopathological examinations. Dehydration was the most common cause of death. Lead poisoning, trauma, emaciation (starvation) and trombidiosis were other causes of death; nonfatal nocardiosis and avian pox also were present. There was no evidence that ingested plastic caused mechanical lesions or mortality in 1987, but most of the chicks had considerably less plastic in them than chicks from earlier years. Human activity (lead poisoning and vehicular trauma) caused mortality at Midway Atoll and represented additive mortality for pre-fledgling albatrosses.

  3. Investigation on the Possible Relationship between Magnetic Pulsations and Earthquakes

    Science.gov (United States)

    Jusoh, M.; Liu, H.; Yumoto, K.; Uozumi, T.; Takla, E. M.; Yousif Suliman, M. E.; Kawano, H.; Yoshikawa, A.; Asillam, M.; Hashim, M.

    2012-12-01

    The sun is the main source of energy to the solar system, and it plays a major role in affecting the ionosphere, atmosphere and the earth surface. The connection between solar wind and the ground magnetic pulsations has been proven empirically by several researchers previously (H. J. Singer et al., 1977, E. W. Greenstadt, 1979, I. A. Ansari 2006 to name a few). In our preliminary statistical analysis on relationship between solar and seismic activities (Jusoh and Yumoto, 2011, Jusoh et al., 2012), we observed a high possibility of solar-terrestrial coupling. We observed high tendency of earthquakes to occur during lower phase solar cycles which significantly related with solar wind parameters (i.e solar wind dynamic pressure, speed and input energy). However a clear coupling mechanism was not established yet. To connect the solar impact on seismicity, we investigate the possibility of ground magnetic pulsations as one of the connecting agent. In our analysis, the recorded ground magnetic pulsations are analyzed at different ranges of ultra low frequency; Pc3 (22-100 mHz), Pc4 (6.7-22 mHz) and Pc5 (1.7-6.7 mHz) with the occurrence of local earthquake events at certain time periods. This analysis focuses at 2 different major seismic regions; north Japan (mid latitude) and north Sumatera, Indonesia (low latitude). Solar wind parameters were obtained from the Goddard Space Flight Center, NASA via the OMNIWeb Data Explorer and the Space Physics Data Facility. Earthquake events were extracted from the Advanced National Seismic System (ANSS) database. The localized Pc3-Pc5 magnetic pulsations data were extracted from Magnetic Data Acquisition System (MAGDAS)/Circum Pan Magnetic Network (CPMN) located at Ashibetsu (Japan); for earthquakes monitored at north Japan and Langkawi (Malaysia); for earthquakes observed at north Sumatera. This magnetometer arrays has established by International Center for Space Weather Science and Education, Kyushu University, Japan. From the

  4. A remark concerning Chandrasekhar's derivation of the pulsation equation for relativistic stars

    Energy Technology Data Exchange (ETDEWEB)

    Knutsen, Henning; Pedersen, Janne [Stavanger University, 4036 Stavanger (Norway)

    2007-01-15

    It is shown that Chandrasekhar gives some misleading comments concerning his method to derive the pulsation equation for relativistic stars. Strictly following his procedure and approximations, we find that this equation should contain an extra term which destroys the beauty and simplicity of the pulsation equation. However, using a better approximation, we find that just this extra term cancels, and the nice original version of the pulsation equation is correct after all.

  5. PATHOLOGICAL AND SERUM BIOCHEMICAL EFFECTS OF SALINOMYCIN ON LAYER CHICKS

    Directory of Open Access Journals (Sweden)

    F. RIZVI, A. D. ANJUM, A. KHAN, M. MOHSAN AND M. SHAZAD

    2008-01-01

    Full Text Available Effects of continuous and over dosage of salinomycin was studied experimentally in layer chicks.Salinomycin was given to layers @ 60, 120 and 180 ppm in feed up to the age of 12 weeks. During the courseof trial, the birds of all groups were active and did not show any clinical signs. Body weight started decreasingsignificantly (P<0.001 in chicks receiving 60, 120 and 180 ppm salinomycin compared to the control groupfrom the 11th, 5th and 3rd week onward, respectively. Feed conversion ratio at 12th week was 3.537 in the controlcompared with 3.701, 4.250 and 4.465 in layer chicks given salinomycin at the rate of 60, 120 and 180 ppm,respectively. Absolute weight of liver at 12th week and absolute weight of kidneys throughout the experimentdecreased significantly (P<0.001 in chicks receiving 180 ppm salinomycin. Concentrations of AST, ALT,blood urea and creatinine were higher in layers receiving 180 ppm salinomycin, while serum total bilirubinconcentration was increased significantly (P<0.001 in layers receiving 120 and 180 ppm salinomycin. No grosslesions were observed in liver and kidneys of layers receiving various doses of salinomycin. Microscopically,there was congestion of liver sinusides and vacuolization of hepatocytes in chicks receiving 180 ppmsalinomycin. There was hydropic degeneration of tubular epithelium, degeneration and desquamation of most ofcells of Bowman’s capsule epithelium of kidneys in birds receiving 180 ppm salinomycin. Higher doses ofsalinomycin seem to alter liver and kidney functions subclinically in layer chicks.

  6. Morphometrics of corneal growth in chicks raised in constant light.

    Science.gov (United States)

    Wahl, Christina; Li, Tong; Choden, Tsering; Howland, Howard

    2009-03-01

    In this study we wish to augment our understanding of the effect of environment on corneal growth and morphology. To understand how corneal development of chicks raised in constant light differs from that of 'normal' eyes exposed to cyclic periods of light and dark, white Leghorn chicks were raised under either constant light (approximately 700 lux at cage top) or in 12 h light/12 h dark conditions for up to 12 weeks after hatching. To determine whether corneal expansion is uniform, some birds from each group received corneal tattoos for periodic photographic assessment. By 16 days of age, constant light corneas weighed less than light/dark regimen corneas [7.39 +/- 0.35 mg (SE) vs. 8.47 mg +/- 0.26 mg SE wet weight, P < or = 0.05], and corresponding differences were seen in corneal dry weights. Spatial expansion of the corneal surface was uniform in both groups, but the rate of expansion was slower in constant light chicks [0.0327 +/- 0.009 (SE) vs. 0.144 +/- 0.018 (SE) mm(2) day(-1) for normal chicks, P < or = 0.001]. At 1 day of age, there were 422 +/- 12.5 (SE) stromal cells 0.01 mm(-2) in the central cornea and 393 +/- 21.5 (SE) stromal cells 0.01 mm(-2 )peripherally. Although this difference is not statistically significant, the cell densities in the central cornea were always larger than those of the peripheral cornea in all eight measurements over a 10.5-week period, and this difference is significant (P < or = 0.008, binomial test). Light/dark regimen birds show no such consistent difference in cell densities between central and peripheral corneas. Thus, the density distribution of corneal stromal cells of chicks grown in constant light differs from that of normal chicks. Taken together, all these observations suggest that diurnal cycles of light and darkness are necessary for normal corneal growth.

  7. Immunization of young chicks using graded dose of wild strain of Eimeria tenella

    Directory of Open Access Journals (Sweden)

    E.N. Kimbita

    2005-09-01

    Full Text Available A wild strain of Eimeria tenella was isolated and utilized for immunization studies. Its optimal sporulation was attained at room temperature 24-25 °C after 24-48 h. Two groups of chicks were immunized by dosing a graded dose of five oocysts/chick/day for 6 days followed by 50 oocysts/chick/day for 7 days. A third group was not immunized and served as a negative control. Immunized chicks gained mass at the same rate as unimmunized ones, but when challenged with 200 000 oocysts/chick, mass gains declined in the unimmunized group. The growth rate of immunized chicks was not affected by challenge (P > 0.05. Upon challenge, unimmunized chicks produced significantly more oocysts than immunized chicks (P < 0.005. Immunized chicks withstood a challenged with 200 000 oocysts/chick without developing any clinical signs whereas the unimmunized chicks developed typical clinical signs of coccidiosis. Unimmunized chicks had significantly more severe lesions in the caecum than any other group (P > 0.005 and also produced significantly more oocysts than any other group (P > 0.005.

  8. Interpreting variation in growth of Eurasian Spoonbill chicks: disentangling the effects of age, sex and environment

    NARCIS (Netherlands)

    Lok, T.; Overdijk, O.; Piersma, T.

    2014-01-01

    Chick body condition can be a sensitive indicator of local environmental conditions and has been shown to be correlated with chick survival. Designing a reliable index of chick body condition for a given species from a single measurement point requires knowledge about the extent of variation in body

  9. First Satellite Imaging of Auroral Pulsations by the Fast Auroral Imager on e-POP

    Science.gov (United States)

    Lui, A.; Cogger, L.; Howarth, A. D.; Yau, A. W.

    2015-12-01

    We report the first satellite imaging of auroral pulsations by the Fast Auroral Imager (FAI) onboard the Enhanced Polar Outflow Probe (e-POP) satellite. The near-infrared camera of FAI is capable of providing up to two auroral images per second, ideal for investigation of pulsating auroras. The auroral pulsations were observed within the auroral bulge formed during a substorm interval on 2014 February 19. This first satellite view of these pulsations from FAI reveals that (1) several pulsating auroral channels (PACs) occur within the auroral bulge, (2) periods of the intensity pulsations span over one decade within the auroral bulge, and (3) there is no apparent trend of longer pulsation periods associated with higher latitudes for these PACs. Although PACs resemble in some respect stable pulsating auroras reported previously but they have several important differences in characteristics.PACs are not embedded in or emerging from omega bands or torches and are located at significant distances from the equatorward boundary of the auroral oval, unlike the characteristics of stable pulsating auroras.

  10. Studies of the Long Secondary Periods in Pulsating Red Giants. II. Lower-Luminosity Stars

    CERN Document Server

    Percy, John R

    2016-01-01

    We have used AAVSO visual and photoelectric V data, and the AAVSO time-series package VSTAR and the Lomb-Scargle time-series algorithm to determine improved pulsation periods, "long secondary periods" (LSPs). and their amplitudes in 51 shorter-period pulsating red giants in the AAVSO photoelectric photometry program, and the AAVSO LPV (long period variable) binocular program. As is well known, radial pulsation becomes detectable in red giants at about spectral type M0, with periods of about 20 days. We find that the LSP phenomenon is also first detectable at about M0. Pulsation and LSP amplitudes increase from near zero to about 0.1 at pulsation periods of about 100 days. At longer periods, the pulsation amplitudes continue to increase, but the LSP amplitudes are generally between 0.1 and 0.2 on average. The ratios of LSP to pulsation period cluster around 5 and 10, presumably depending on whether the pulsation period is the fundamental or first overtone. The pulsation and LSP phase curves are generally close...

  11. New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars

    CERN Document Server

    Hubrig, S; De Cat, P; Schöller, M; Morel, T; Ilyin, I

    2009-01-01

    We present the results of the continuation of our magnetic survey with FORS1 at the VLT of a sample of B-type stars consisting of confirmed or candidate beta Cephei stars and Slowly Pulsating B stars. Roughly one third of the studied beta Cephei stars have detected magnetic fields. The fraction of magnetic Slowly Pulsating B and candidate Slowly Pulsating B stars is found to be higher, up to 50%. We find that the domains of magnetic and non-magnetic pulsating stars in the H-R diagram largely overlap, and no clear picture emerges as to the possible evolution of the magnetic field across the main sequence.

  12. White Dwarf Period Tables I. Pulsators with hydrogen-dominated atmospheres

    Science.gov (United States)

    Bognar, Zs.; Sodor, A.

    2016-09-01

    We aimed at collecting all known white dwarf pulsators with hydrogen-dominated atmospheres and list their main photometric and atmospheric parameters together with their pulsation periods and amplitudes observed at different epochs. For this purpose, we explored the pulsating white dwarf related literature with the systematic use of the SIMBAD and the NASA's Astrophysics Data System (ADS) databases. We summarized our results in four tables listing seven ZZ Ceti stars in detached white dwarf plus main-sequence binaries, seven extremely low-mass DA pulsators, three hot DAVs and 180 ZZ Ceti stars.

  13. White Dwarf Period Tables - I. Pulsators with hydrogen-dominated atmospheres

    CERN Document Server

    Bognár, Zs

    2016-01-01

    We aimed at collecting all known white dwarf pulsators with hydrogen-dominated atmospheres and list their main photometric and atmospheric parameters together with their pulsation periods and amplitudes observed at different epochs. For this purpose, we explored the pulsating white dwarf related literature with the systematic use of the SIMBAD and the NASA's Astrophysics Data System (ADS) databases. We summarized our results in four tables listing seven ZZ Ceti stars in detached white dwarf plus main-sequence binaries, seven extremely low-mass DA pulsators, three hot DAVs and 180 ZZ Ceti stars.

  14. Asteroseismology and forced oscillations of HD 209295, the first member of two classes of pulsating star

    CERN Document Server

    Handler, G; Shobbrook, R R; Koen, C; Bruch, A; Romero-Colmenero, E; Pamyatnykh, A A; Willems, B; Eyer, L; James, D J; Maas, T; Crause, L A

    2001-01-01

    We report the discovery of both intermediate-order gravity mode and low-order pressure mode pulsation in the same star, HD 209295. It is therefore both a gamma Doradus and a delta Scuti star, which makes it the first confirmed member of two classes of pulsating star. This object is located in a close binary system with an unknown, but likely degenerate companion in an eccentric orbit, and some of the gamma Doradus pulsation frequencies are exact integer multiples of the orbital frequency. We suggest that these pulsations are tidally excited. HD 209295 may be the progenitor of an intermediate-mass X-Ray binary.

  15. On the periodic variations of secondary cosmic rays and the geomagnetic Pc4 pulsations in BMAr

    Directory of Open Access Journals (Sweden)

    I. M. Martin

    Full Text Available In a set of balloon flights in the Brazilian magnetic anomaly region (BMAr short time periodic variations were observed, i.e. pulsation, of secondary charged and neutral particle fluxes, X- and -ray fluxes with amplitudes of about 2–4%. The pulsations are accompanied by the geomagnetic Pc4 pulsations and have similar periodicity. The phenomenon was observed over various local times and in quiet and disturbed magnetospheric conditions. One of the explanations of this effect, i.e. periodic variation of local cut-off rigidity, and following pulsations of primary and secondary cosmic ray intensity is suggested.

  16. Ethanol- and/or Taurine-Induced Oxidative Stress in Chick Embryos

    Directory of Open Access Journals (Sweden)

    Emily J. Berning

    2013-01-01

    Full Text Available Because taurine alleviates ethanol- (EtOH- induced lipid peroxidation and liver damage in rats, we asked whether exogenous taurine could alleviate EtOH-induced oxidative stress in chick embryos. Exogenous EtOH (1.5 mmol/Kg egg or 3 mmol/Kg egg, taurine (4 μmol/Kg egg, or EtOH and taurine (1.5 mmol EtOH and 4 μmol taurine/Kg egg or 3 mmol EtOH and 4 μmol taurine/Kg egg were injected into fertile chicken eggs during the first three days of embryonic development (E0–2. At 11 days of development (midembryogenesis, serum taurine levels and brain caspase-3 activities, homocysteine (HoCys levels, reduced glutathione (GSH levels, membrane fatty acid composition, and lipid hydroperoxide (LPO levels were measured. Early embryonic EtOH exposure caused increased brain apoptosis rates (caspase-3 activities; increased brain HoCys levels; increased oxidative-stress, as measured by decreased brain GSH levels; decreased brain long-chain polyunsaturated levels; and increased brain LPO levels. Although taurine is reported to be an antioxidant, exogenous taurine was embryopathic and caused increased apoptosis rates (caspase-3 activities; increased brain HoCys levels; increased oxidative-stress (decreased brain GSH levels; decreased brain long-chain polyunsaturated levels; and increased brain LPO levels. Combined EtOH and taurine treatments also caused increased apoptosis rates and oxidative stress.

  17. Immunocytochemical analysis of intermediate filaments in embryonic heart cells with monoclonal antibodies to desmin.

    Science.gov (United States)

    Danto, S I; Fischman, D A

    1984-06-01

    Monoclonal antibodies ( McAbs ) have been generated against a preparation of intermediate filament proteins (IFP) from adult chicken gizzard. Two antibodies, D3 and D76 , have been characterized in detail. They bind specifically to desmin but recognize different epitopes. In the adult chicken, both McAbs produced equivalent immunofluorescent staining patterns, reacting in frozen sections with all forms of muscle tissue, including vascular smooth muscle, but with no other tissue types. In isolated skeletal myofibrils and in longitudinal frozen sections of cardiac and skeletal muscle, desmin was detected with both McAbs at the Z-band and in longitudinally-oriented filament bundles between myofibrils. In contrast to these results in the adult, the intermediate filaments (IF) of embryonic cardiac myocytes in primary cultures were decorated only with McAb D3, whereas McAb D76 was completely unreactive with these cells. Similarly, frozen sections through the heart at early stages of embryonic chick development (Hamburger-Hamilton stages 17-18) revealed regions of myocytes, identified by double immunofluorescence with myosin-specific McAbs , that were unstained with McAb D76 even though similar regions were stained by McAb D3. That McAb D76 reacted with desmin in all adult cardiac myocytes but not with all embryonic heart cells indicates that embryonic and adult cardiac IF are immunologically distinct and implies a conversion in IF immunoreactivity during cardiac development.

  18. Embryonic Stem Cell Markers

    Directory of Open Access Journals (Sweden)

    Lan Ma

    2012-05-01

    Full Text Available Embryonic stem cell (ESC markers are molecules specifically expressed in ES cells. Understanding of the functions of these markers is critical for characterization and elucidation for the mechanism of ESC pluripotent maintenance and self-renewal, therefore helping to accelerate the clinical application of ES cells. Unfortunately, different cell types can share single or sometimes multiple markers; thus the main obstacle in the clinical application of ESC is to purify ES cells from other types of cells, especially tumor cells. Currently, the marker-based flow cytometry (FCM technique and magnetic cell sorting (MACS are the most effective cell isolating methods, and a detailed maker list will help to initially identify, as well as isolate ESCs using these methods. In the current review, we discuss a wide range of cell surface and generic molecular markers that are indicative of the undifferentiated ESCs. Other types of molecules, such as lectins and peptides, which bind to ESC via affinity and specificity, are also summarized. In addition, we review several markers that overlap with tumor stem cells (TSCs, which suggest that uncertainty still exists regarding the benefits of using these markers alone or in various combinations when identifying and isolating cells.

  19. Evaluation of skeletal tissue repair, part 2: enhancement of skeletal tissue repair through dual-growth-factor-releasing hydrogels within an ex vivo chick femur defect model.

    Science.gov (United States)

    Smith, E L; Kanczler, J M; Gothard, D; Roberts, C A; Wells, J A; White, L J; Qutachi, O; Sawkins, M J; Peto, H; Rashidi, H; Rojo, L; Stevens, M M; El Haj, A J; Rose, F R A J; Shakesheff, K M; Oreffo, R O C

    2014-10-01

    There is an unmet need for improved, effective tissue engineering strategies to replace or repair bone damaged through disease or injury. Recent research has focused on developing biomaterial scaffolds capable of spatially and temporally releasing combinations of bioactive growth factors, rather than individual molecules, to recapitulate repair pathways present in vivo. We have developed an ex vivo embryonic chick femur critical size defect model and applied the model in the study of novel extracellular matrix (ECM) hydrogel scaffolds containing spatio-temporal combinatorial growth factor-releasing microparticles and skeletal stem cells for bone regeneration. Alginate/bovine bone ECM (bECM) hydrogels combined with poly(d,l-lactic-co-glycolic acid) (PDLLGA)/triblock copolymer (10-30% PDLLGA-PEG-PLDLGA) microparticles releasing dual combinations of vascular endothelial growth factor (VEGF), chondrogenic transforming growth factor beta 3 (TGF-β3) and the bone morphogenetic protein BMP2, with human adult Stro-1+bone marrow stromal cells (HBMSCs), were placed into 2mm central segmental defects in embryonic day 11 chick femurs and organotypically cultured. Hydrogels loaded with VEGF combinations induced host cell migration and type I collagen deposition. Combinations of TGF-β3/BMP2, particularly with Stro-1+HBMSCs, induced significant formation of structured bone matrix, evidenced by increased Sirius red-stained matrix together with collagen expression demonstrating birefringent alignment within hydrogels. This study demonstrates the successful use of the chick femur organotypic culture system as a high-throughput test model for scaffold/cell/growth factor therapies in regenerative medicine. Temporal release of dual growth factors, combined with enriched Stro-1+HBMSCs, improved the formation of a highly structured bone matrix compared to single release modalities. These studies highlight the potential of a unique alginate/bECM hydrogel dual growth factor release

  20. Influence of a mobile robot on the spatial behaviour of quail chicks

    Energy Technology Data Exchange (ETDEWEB)

    De Margerie, E; Lumineau, S; Houdelier, C; Richard Yris, M-A, E-mail: emmanuel.demargerie@univ-rennes1.fr [CNRS UMR 6552 Ethologie Animale et Humaine, Universite Rennes 1, Rennes (France)

    2011-09-15

    Quail chicks encountered an autonomous mobile robot during their early development. The robot incorporated a heat source that stimulated following of chicks. The spatial behaviour of grown-up chicks was tested in an exploration test and a detour test. Chicks that grew with the mobile robot exhibited better spatial abilities than chicks grown with a static heat source. We discuss these results in the perspective of animal-robot interaction and of the role of early spatial experience on the behavioural development. (communication)

  1. Analysis of cCx39 expression pattern during chick development.

    Science.gov (United States)

    Nicotra, Annalisa; Cicirata, Federico; Martinez, Salvador

    2004-02-20

    The present study reports the expression pattern of connexin39 (cCx39) in chick embryos at different stages of central nervous system development. We examined the expression between HH17 and HH40 developmental stages of chicken embryos by in situ hybridization (ISH) technique. Connexin39 was first expressed at HH17. It stained neuroepithelial cells in the optic (OV) and telencephalic (TEL) vesicles, plus in the superficial mesenchyme of the two rostral branchial arches (maxilar and mandibular). These cells probably originated from the neural crest. This expression pattern changed drastically between stages HH17 and HH23, while it showed relatively little modifications from HH23 to HH29. At these times, connexin39 was expressed in three regions: the telencephalic vesicle, the diencephalon and the isthmus. At later stages, HH35 and HH40, connexin39 was mainly expressed in the ventricular epithelium and three cell layers of the stratum griseum and fibrosum superficialis (SGFS) in the optic tectum, as well as in granular and nuclear cells in the cerebellum. In conclusion, the expression pattern of connexin39 in embryonic nervous system is dynamic. This pattern is different from, and in some aspects complementary to, those showed by other connexins during brain development.

  2. Type II cytokeratin gene expression is indicative of early cell differentiation in the chick embryo

    Energy Technology Data Exchange (ETDEWEB)

    Charlebois, T.S.

    1988-01-01

    Embryonic development in vertebrates appears to involve a series of inductive tissue interactions that lead to regional specializations, which eventually become elaborated in the basic body plan of the embryo. The inductive interactions leading to early regionalization of the embryo are often particularly difficult to evaluate because of the absence of available morphological or biochemical evidence that such events have occurred. In the 36 hour chick embryo, the regional subdivision of the early ectoderm is evidence by a marked lens-forming bias in the head ectoderm, which is absent in the presumptive dorsal epidermis of the trunk region. As a strategy for isolating genes whose differential expression might reflect this regional subdivision, a cDNA library from 36 hour embryos was prepared and screened for differential hybridization to ({sup 32}P)cDNA probes synthesized using template RNA isolated from 36 hour head ectoderm and trunk ectoderm. A cDNA clone (T4) was isolated which hybridizes to transcripts present at much higher levels in trunk ectoderm than in head ectoderm. Partial nucleotide and deduced amino acid sequences of this clone indicate that it represents a gene encoding a type II cytokeratin. The distribution of transcripts complementary to the T4 probe was evaluated in early embryos using RNA gel blot analysis and in situ hybridization to tissue sections.

  3. Complex and dynamic patterns of Wnt pathway gene expression in the developing chick forebrain

    Directory of Open Access Journals (Sweden)

    Lumsden Andrew

    2009-09-01

    Full Text Available Abstract Background Wnt signalling regulates multiple aspects of brain development in vertebrate embryos. A large number of Wnts are expressed in the embryonic forebrain; however, it is poorly understood which specific Wnt performs which function and how they interact. Wnts are able to activate different intracellular pathways, but which of these pathways become activated in different brain subdivisions also remains enigmatic. Results We have compiled the first comprehensive spatiotemporal atlas of Wnt pathway gene expression at critical stages of forebrain regionalisation in the chick embryo and found that most of these genes are expressed in strikingly dynamic and complex patterns. Several expression domains do not respect proposed compartment boundaries in the developing forebrain, suggesting that areal identities are more dynamic than previously thought. Using an in ovo electroporation approach, we show that Wnt4 expression in the thalamus is negatively regulated by Sonic hedgehog (Shh signalling from the zona limitans intrathalamica (ZLI, a known organising centre of forebrain development. Conclusion The forebrain is exposed to a multitude of Wnts and Wnt inhibitors that are expressed in a highly dynamic and complex fashion, precluding simple correlative conclusions about their respective functions or signalling mechanisms. In various biological systems, Wnts are antagonised by Shh signalling. By demonstrating that Wnt4 expression in the thalamus is repressed by Shh from the ZLI we reveal an additional level of interaction between these two pathways and provide an example for the cross-regulation between patterning centres during forebrain regionalisation.

  4. Selective innervation of fast and slow muscle regions during early chick neuromuscular development.

    Science.gov (United States)

    Rafuse, V F; Milner, L D; Landmesser, L T

    1996-11-01

    The electrical properties of adult motoneurons are well matched to the contractile properties of the fast or slow muscle fibers that they innervate. How this precise matching occurs developmentally is not known. To investigate whether motoneurons exhibit selectivity in innervating discrete muscle regions, containing either fast or slow muscle fibers during early neuromuscular development, we caused embryonic chick hindlimb muscles to become innervated by segmentally inappropriate motoneurons. We used the in vitro spinal cord-hindlimb preparation to identify electrophysiologically the pools of foreign motoneurons innervating the posterior iliotibialis (pITIB), an all-fast muscle, and the iliofibularis (IFIB), a partitioned muscle containing discrete fast and slow regions. The results showed that the pITIB and the fast region of the IFIB were exclusively innervated by motoneurons that normally supply fast muscles. In contrast, the slow region of the IFIB was always innervated by motoneuron pools that normally supply slow muscles. Some experimental IFIB muscles lacked a fast region and were innervated solely by "slow" motoneurons. In addition, the intramuscular nerve branching patterns were always appropriate to the fast-slow nature of the muscle (region) innervated. The selective innervation was found early in the motoneuron death period, and we found no evidence that motoneurons grew into appropriate muscle regions, but failed to form functional contacts. Together, these results support the hypothesis that different classes of motoneurons exhibit molecular differences that allow them to project selectively to, and innervate, muscle fibers of the appropriate type during early neuromuscular development.

  5. The In Ovo Chick Chorioallantoic Membrane (CAM) Assay as an Efficient Xenograft Model of Hepatocellular Carcinoma.

    Science.gov (United States)

    Li, Michael; Pathak, Ravi R; Lopez-Rivera, Esther; Friedman, Scott L; Aguirre-Ghiso, Julio A; Sikora, Andrew G

    2015-10-09

    The chick chorioallantoic membrane (CAM) begins to develop by day 7 after fertilization and matures by day 12. The CAM is naturally immunodeficient and highly vascularized, making it an ideal system for tumor implantation. Furthermore, the CAM contains extracellular matrix proteins such as fibronectin, laminin, collagen, integrin alpha(v)beta3, and MMP-2, making it an attractive model to study tumor invasion and metastasis. Scientists have long taken advantage of the physiology of the CAM by using it as a model of angiogenesis. More recently, the CAM assay has been modified to work as an in vivo xenograft model system for various cancers that bridges the gap between basic in vitro work and more complex animal cancer models. The CAM assay allows for the study of tumor growth, anti-tumor therapies, and pro-tumor molecular pathways in a biologically relevant system that is both cost- and time-effective. Here, we describe the development of CAM xenograft model of hepatocellular carcinoma (HCC) with embryonic survival rates of up to 93% and reliable tumor take leading to growth of three-dimensional, vascularized tumors.

  6. Metamizole Sodium Induces Neural Tube Defects in a Chick Embryo Model.

    Science.gov (United States)

    Guvenc, Yahya; Billur, Deniz; Aydin, Sevim; Ozeren, Ersin; Demirci, Adnan; Alagoz, Fatih; Dalgic, Ali; Belen, Deniz

    The aim of this study was to investigate the effects of metamizole sodium on neural tube development in the early stage chick embryo model that complies with the first month of embryonic development in mammals. A total of 40 fertilized chicken eggs were divided into 4 equal groups. The eggs were incubated in the incubator at a temperature of 37.8±2°C with 60±5% humidity. Group A was the control, Group B was administered physiological saline, Group C was administered 30 mg/kg metamizole sodium (based on the therapeutic index range of it used in humans) and Group D was administered 90 mg/kg metamizole sodium. All embryos were removed from the egg at the 48th hour and morphologically and histologically examined. Normal development was seen and the neural tube was closed in 17 embryos in Groups A and B. A neural tube defect was seen in 2 embryos in group A and in 1 embryo in group B. A neural tube closure defect was seen in all embryos in group C and 9 embryos in group D. There was 1 dead embryo in Group D. Metamizole sodium was seen to produce a neural tube defect in the chicken embyro model.

  7. Toxicity of metals to chick embryos

    Energy Technology Data Exchange (ETDEWEB)

    Birge, W.J.; Roberts, O.W.

    1976-09-01

    A comparative index to the embryopathic effects of a number of metals which may appear as trace contaminants in avian food sources is given. Chicken eggs (White Plymouth Rock strain) were treated by yolk injection with sodium arsenite, sodium selenate and chloride salts of cadmium, lead, mercury, methyl mercury and zinc immediately prior to incubation. Eggs were positioned horizontally for 24 hr before injection, allowing the embryonic blastodisc to orient away from the point of needle entry. The test aliquot was deposited in a needle track extending through the diameter of each egg yolk, thus facilitating the uniform distribution of the toxicant. Percent survival was determined as hatchability in experimental populations/hatchability of controls. Survival rates at a concentration of 0.001 ppM were 64-66% for selenium, arsenic and cadmium at the same concentration, survival rates were 74-83 percent for lead, methyl mercury, inorganic mercury, and zinc. All metals produced appreciable percentages of teratogenic survivors when administered at or above their TL/sub 50/ concentrations. The greatest percentages of defective survivors were always at the highest test concentrations which permitted survival, ranging from 0.5 ppM for selenium and arsenic to 10.0 ppM for mercury and zinc. (MFB)

  8. Effects of Senna occidentalis on chick bursa of Fabricius.

    Science.gov (United States)

    Silva, Tereza C; Gorniak, Silvana L; Oloris, Silvia C S; Raspantini, Paulo C; Haraguchi, Mitsue; Dagli, Maria L Z

    2003-12-01

    Senna occidentalis (L) Link (formerly called Cassia occidentalis) is a toxic leguminous plant found ubiquitously as a contaminant of crops. All parts of the plant are toxic, but most of the S. occidentalis toxicity is found in the seeds. S. occidentalis has been shown to be toxic to several animal species, causing degenerative lesions mainly in muscles. This is the first report describing alterations in chick lymphoid organs caused by S. occidentalis seeds. The objectives of this study were to describe the effects of the treatment with seeds and its fraction external tegument (TE) on the development of chicks and their lymphoid organs bursa of Fabricius and spleen. Chicks that received a commercial ration with 1% TE had reduced body and lymphoid organ weights. The bursa of Fabricius presented reduction in the diameters of the follicles, and in the thickness of the cortical and medullary regions. The spleen presented depleted lymphoid tissue in the white pulp. These results indicate that the active principle of S. occidentalis is more concentrated on its TE fraction, and that it can cause weight loss as well as alterations in the lymphoid organs in chicks. The consequences of these alterations should be further investigated.

  9. Comparative Performance Of Broiler Chicks fed Diets Containing ...

    African Journals Online (AJOL)

    Comparative Performance Of Broiler Chicks fed Diets Containing Differently Processed ... A 28-day feeding trial was conducted to determine the effects of dietary inclusion of ... The first batch was soaked in 3% Ca(OH)2 for 48 hours. ... performance of the birds in terms of feed intake, growth rate and feed conversion ratio.

  10. Neurotoxic effect of the dithiocarbamate tecoram on the chick embryo

    NARCIS (Netherlands)

    Steenis, G. van; Logten, M.J. van

    1971-01-01

    Tecoram, when administered at doses of 0.01, 0.1, 1 or 10 mg per egg in propylene glycol or in saline to chick embryos caused paralysis, shortening of the extremities, muscular atrophy, dwarfing and death. Microscopically there were signs of peripheral neuropathy, mainly confined to the distal parts

  11. Safety of West Nile Virus vaccines in sandhill crane chicks

    Science.gov (United States)

    Olsen, G.H.; Miller, K.J.; Docherty, D.E.; Bochsler, V.S.; Folk, Martin J.; Nesbitt, Stephen A.

    2008-01-01

    West Nile virus arrived in North America in 1999 and has spread across the continent in the ensuing years. The virus has proven deadly to a variety of native avian species including sandhill cranes (Grus canadensis). In order to provide safe and efficacious protection for captive and released populations of whooping cranes (G. americana), we have conducted a series of four research projects. The last of these was a study of the effects of two different West Nile virus vaccines on young Florida sandhill crane (G. c. pratensis) chicks and subsequent challenge with the virus. We found that vaccinating crane chicks as early as day 7 post-hatch caused no adverse reactions or noticeable morbidity. We tested both a commercial equine vaccine West Nile - Innovator (Fort Dodge Laboratories, Fort Dodge, Iowa) and a new recombinant DNA vaccine (Centers for Disease Control). We had a 33% mortality in control chicks (n =6) from West Nile virus infection, versus 0% mortality in two groups of vaccinated chicks (n = 12), indicating the two vaccines tested were not only safe but effective in preventing West Nile virus.

  12. Effects of begging on growth rates of nestling chicks

    NARCIS (Netherlands)

    Rodriguez-Girones, MA; Zuniga, JM; Redondo, T

    2001-01-01

    We investigated whether an increase in begging levels delays growth of chicks. In experiment 1, we hand-reared nine pairs of ring dove squabs, divided into a control and a begging group. All squabs received similar amounts of food, but those in the begging group had to beg for a prolonged period in

  13. Ex Ovo Model for Directly Visualizing Chick Embryo Development

    Science.gov (United States)

    Dorrell, Michael I.; Marcacci, Michael; Bravo, Stephen; Kurz, Troy; Tremblay, Jacob; Rusing, Jack C.

    2012-01-01

    We describe a technique for removing and growing chick embryos in culture that utilizes relatively inexpensive materials and requires little space. It can be readily performed in class by university, high school, or junior high students, and teachers of any grade level should be able to set it up for their students. Students will be able to…

  14. Artificially Increased Yolk Hormone Levels and Neophobia in Domestic Chicks.

    Science.gov (United States)

    Bertin, Aline; Arnould, Cécile; Moussu, Chantal; Meurisse, Maryse; Constantin, Paul; Leterrier, Christine; Calandreau, Ludovic

    2015-11-30

    In birds there is compelling evidence that the development and expression of behavior is affected by maternal factors, particularly via variation in yolk hormone concentrations of maternal origin. In the present study we tested whether variation in yolk hormone levels lead to variation in the expression of neophobia in young domestic chicks. Understanding how the prenatal environment could predispose chicks to express fear-related behaviors is essential in order to propose preventive actions and improve animal welfare. We simulated the consequences of a maternal stress by experimentally enhancing yolk progesterone, testosterone and estradiol concentrations in hen eggs prior to incubation. The chicks from these hormone-treated eggs (H) and from sham embryos (C) that received the vehicle-only were exposed to novel food, novel object and novel environment tests. H chicks approached a novel object significantly faster and were significantly more active in a novel environment than controls, suggesting less fearfulness. Conversely, no effect of the treatment was found in food neophobia tests. Our study highlights a developmental influence of yolk hormones on a specific aspect of neophobia. The results suggest that increased yolk hormone levels modulate specifically the probability of exploring novel environments or novel objects in the environment.

  15. Artificially Increased Yolk Hormone Levels and Neophobia in Domestic Chicks

    Directory of Open Access Journals (Sweden)

    Aline Bertin

    2015-11-01

    Full Text Available In birds there is compelling evidence that the development and expression of behavior is affected by maternal factors, particularly via variation in yolk hormone concentrations of maternal origin. In the present study we tested whether variation in yolk hormone levels lead to variation in the expression of neophobia in young domestic chicks. Understanding how the prenatal environment could predispose chicks to express fear-related behaviors is essential in order to propose preventive actions and improve animal welfare. We simulated the consequences of a maternal stress by experimentally enhancing yolk progesterone, testosterone and estradiol concentrations in hen eggs prior to incubation. The chicks from these hormone-treated eggs (H and from sham embryos (C that received the vehicle-only were exposed to novel food, novel object and novel environment tests. H chicks approached a novel object significantly faster and were significantly more active in a novel environment than controls, suggesting less fearfulness. Conversely, no effect of the treatment was found in food neophobia tests. Our study highlights a developmental influence of yolk hormones on a specific aspect of neophobia. The results suggest that increased yolk hormone levels modulate specifically the probability of exploring novel environments or novel objects in the environment.

  16. Effects of begging on growth rates of nestling chicks

    NARCIS (Netherlands)

    Rodriguez-Girones, MA; Zuniga, JM; Redondo, T

    2001-01-01

    We investigated whether an increase in begging levels delays growth of chicks. In experiment 1, we hand-reared nine pairs of ring dove squabs, divided into a control and a begging group. All squabs received similar amounts of food, but those in the begging group had to beg for a prolonged period in

  17. Mechanotransduction in mechanically coupled pulsating cells: transition to collective constriction and mesoderm invagination simulation

    Science.gov (United States)

    Driquez, Benjamin; Bouclet, Adrien; Farge, Emmanuel

    2011-12-01

    Embryonic differentiation and morphogenesis require the coordination of the cascades of gene product expression with the morphogenetic sequence of development. The influence of mechanical deformations driven by morphogenetic movements on biochemical activities was recently revealed by the existence of mechanotransduction processes in development, involving both gene transcription and protein behaviour. In the early Drosophila embryo, apical stabilization of Myosin-II leading to mesoderm invagination at the onset of gastrulation was proposed to be triggered in response to the activation of the Fog mechanotransduction pathway by the Snail-dependent active mechanical oscillations of cell apex sizes. Here we simulate the mesoderm as mechanically coupled cells, with pulsatile forces of constriction at the cell level mimicking Snail-dependent active fluctuations of apexes. We define a critical apex diameter triggering active constriction that mimics the activation of the Fog mechanotransduction pathway leading to cell constriction. We find that collective movements trigger the dynamical transition to constriction predicting the experimental dynamics of mesoderm cell apex size decrease with a modulus of contractility four times higher than the passive modulus of elastic deformation of the cells. The contraction wave is activated in a pulsation frequency-dependent process, and propagates at multicellular scales through local cell-cell mechanical interactions. By reproducing the pattern of Snail and Fog gene product protein expression in a simulation of ventral cells, the model phenocopies the pattern of Myo-II apical stabilization, and the dynamic pattern of constriction that initiates along a central sub-domain of the mesoderm. We propose that multicellular mechanical collective effects couple with mechanotransduction biochemical mechanisms to trigger the transition of collective coordinated constriction, through a mechano-genetic process ensuring efficient and regular

  18. Mechanotransduction in mechanically coupled pulsating cells: transition to collective constriction and mesoderm invagination simulation.

    Science.gov (United States)

    Driquez, Benjamin; Bouclet, Adrien; Farge, Emmanuel

    2011-12-01

    Embryonic differentiation and morphogenesis require the coordination of the cascades of gene product expression with the morphogenetic sequence of development. The influence of mechanical deformations driven by morphogenetic movements on biochemical activities was recently revealed by the existence of mechanotransduction processes in development, involving both gene transcription and protein behaviour. In the early Drosophila embryo, apical stabilization of Myosin-II leading to mesoderm invagination at the onset of gastrulation was proposed to be triggered in response to the activation of the Fog mechanotransduction pathway by the Snail-dependent active mechanical oscillations of cell apex sizes. Here we simulate the mesoderm as mechanically coupled cells, with pulsatile forces of constriction at the cell level mimicking Snail-dependent active fluctuations of apexes. We define a critical apex diameter triggering active constriction that mimics the activation of the Fog mechanotransduction pathway leading to cell constriction. We find that collective movements trigger the dynamical transition to constriction predicting the experimental dynamics of mesoderm cell apex size decrease with a modulus of contractility four times higher than the passive modulus of elastic deformation of the cells. The contraction wave is activated in a pulsation frequency-dependent process, and propagates at multicellular scales through local cell-cell mechanical interactions. By reproducing the pattern of Snail and Fog gene product protein expression in a simulation of ventral cells, the model phenocopies the pattern of Myo-II apical stabilization, and the dynamic pattern of constriction that initiates along a central sub-domain of the mesoderm. We propose that multicellular mechanical collective effects couple with mechanotransduction biochemical mechanisms to trigger the transition of collective coordinated constriction, through a mechano-genetic process ensuring efficient and regular

  19. Appraisal of electromagnetic induction effects on magnetic pulsation studies

    Directory of Open Access Journals (Sweden)

    B. R. Arora

    Full Text Available The quantification of wave polarization characteristics of ULF waves from the geomagnetic field variations is done under ‘a priori’ assumption that fields of internal induced currents are in-phase with the external inducing fields. Such approximation is invalidated in the regions marked by large lateral conductivity variations that perturb the flow pattern of induced currents. The amplitude and phase changes that these perturbations produce, in the resultant fields at the Earth’s surface, make determination of polarization and phase of the oscillating external signals problematic. In this paper, with the help of a classical Pc5 magnetic pulsation event of 24 March 1991, recorded by dense network of magnetometers in the equatorial belt of Brazil, we document the nature and extent of the possible influence of anomalous induction effects in the wave polarization of ULF waves. The presence of anomalous induction effects at selected sites lead to an over estimation of the equatorial enhancement at pulsation period and also suggest changes in the azimuth of ULF waves as they propagate through the equatorial electrojet. Through numerical calculations, it is shown that anomalous horizontal fields, that result from induction in the lateral conductivity distribution in the study region, vary in magnitude and phase with the polarization of external source field. Essentially, the induction response is also a function of the period of external inducing source field. It is further shown that when anomalous induction fields corresponding to the magnitude and polarization of the 24 March 1991 pulsation event are eliminated from observed fields, corrected amplitude in the X and Y horizontal components allows for true characterisation of ULF wave parameters.

    Key words. Geomagnetism and paleomagnetism (geomagnetic induction – Ionosphere (equatorial ionosphere – Magnetospheric physics (magnetosphere-ionosphere interactions

  20. DARK STARS: IMPROVED MODELS AND FIRST PULSATION RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Rindler-Daller, T.; Freese, K. [Department of Physics and Michigan Center for Theoretical Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Montgomery, M. H.; Winget, D. E. [Department of Astronomy, McDonald Observatory and Texas Cosmology Center, University of Texas, Austin, TX 78712 (United States); Paxton, B. [Kavli Insitute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)

    2015-02-01

    We use the stellar evolution code MESA to study dark stars (DSs). DSs, which are powered by dark matter (DM) self-annihilation rather than by nuclear fusion, may be the first stars to form in the universe. We compute stellar models for accreting DSs with masses up to 10{sup 6} M {sub ☉}. The heating due to DM annihilation is self-consistently included, assuming extended adiabatic contraction of DM within the minihalos in which DSs form. We find remarkably good overall agreement with previous models, which assumed polytropic interiors. There are some differences in the details, with positive implications for observability. We found that, in the mass range of 10{sup 4}-10{sup 5} M {sub ☉}, our DSs are hotter by a factor of 1.5 than those in Freese et al., are smaller in radius by a factor of 0.6, denser by a factor of three to four, and more luminous by a factor of two. Our models also confirm previous results, according to which supermassive DSs are very well approximated by (n = 3)-polytropes. We also perform a first study of DS pulsations. Our DS models have pulsation modes with timescales ranging from less than a day to more than two years in their rest frames, at z ∼ 15, depending on DM particle mass and overtone number. Such pulsations may someday be used to identify bright, cool objects uniquely as DSs; if properly calibrated, they might, in principle, also supply novel standard candles for cosmological studies.

  1. Discovery of a new PG 1159 (GW Vir) pulsator

    Science.gov (United States)

    Kepler, S. O.; Fraga, Luciano; Winget, Don Earl; Bell, Keaton; Córsico, Alejandro H.; Werner, Klaus

    2014-08-01

    We report the discovery of pulsations in the spectroscopic PG 1159 type pre-white dwarf SDSS J075415.12 + 085232.18. Analysis of the spectrum by Werner et al. indicated Teff = 120 000 ± 10 000 K, log g = 7.0 ± 0.3, mass {M}=0.52 ± 0.02 M_{⊙}, C/He = 0.33 by number. We obtained time series images with the SOAR 4.1 m telescope and 2.1 m Otto Struve telescope at McDonald Observatory and show the star is also a variable PG 1159 type star, with dominant period of 525 s.

  2. Discovery of a new PG1159 (GW Vir) Pulsator

    CERN Document Server

    Kepler, S O; Winget, Don Earl; Bell, Keaton; Corsico, Alejandro H; Werner, Klaus

    2014-01-01

    We report the discovery of pulsations in the spectroscopic PG 1159 type pre-white dwarf SDSS J075415.12+085232.18. Analysis of the spectrum by Werner, Rauch and Kepler (2014) indicated Teff=120 000+/-10 000 K, log g=7.0+/-0.3, mass M=0.52+/-0.02 Msun, C/He=0.33 by number. We obtained time-series images with the SOAR 4.1 m telescope and 2.1 m Otto Struve telescope at McDonald Observatory and show the star is also a variable PG 1159 type star, with dominant period of 525 s.

  3. Modeling KIC10684673 and KIC12216817 as Single Pulsating Variables

    CERN Document Server

    Turner, Garrison

    2016-01-01

    The raw light curves of both KIC 10684673 and KIC 12216817 show variability. Both are listed in the Kepler Eclipsing Binary Catalog (hereafter KEBC), however both are flagged as uncertain in nature. In the present study we show their light curves can be modeled by considering each target as a single, multi-modal delta Scuti pulsator. While this does not exclude the possibility of eclipsing systems, we argue, while spectroscopy on the systems is still lacking, the delta Scuti model is a simpler explanation and therefore more probable.

  4. DYNAMIC STABILITY OF AXIALLY MOVING VISCOELASTIC BEAMS WITH PULSATING SPEED

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-dong; CHEN Li-qun

    2005-01-01

    Parametric vibration of an axially moving, elastic, tensioned beam with pulsating speed was investigated in the vicinity of subharmonic and combination resonance. The method of averaging was used to yield a set of autonomous equations when the parametric excitation frequency is twice or the combination of the natural frequencies. Instability boundaries were presented in the plane of parametric frequency and amplitude. The analytical results were numerically verified. The effects of the viscoelastic damping, steady speed and tension on the instability boundaries were numerically demonstrated. It is found that the viscoelastic damping decreases the instability regions and the steady speed and the tension make the instability region drift along the frequency axis.

  5. Fibrous osteodystrophy in two Northern Royal albatross chicks (Diomedea sanfordi).

    Science.gov (United States)

    Morgan, K J; Alley, M R; Gartrell, B D; Thompson, K G; Perriman, L

    2011-09-01

    In February 2004, two Northern Royal albatross chicks aged 20 and 25 days old were presented for necropsy. Both chicks had been hand-fed in situ at a breeding colony, from 2-3 days post-hatch. The hand-rearing diet consisted of boneless hoki fillets (Macraronus novaezelandiae), electrolytes, and sooty shearwater (Puffinus griseus) proventricular oil obtained as a by-product of cultural harvest. Routine necropsies on the affected chicks revealed many bones were soft and easily bent. Radiography and histopathology revealed decreased bone density, pathological fractures, and extensive remodelling suggestive of fibrous osteodystrophy. Nutritional secondary hyperparathyroidism, resulting from an imbalance in the dietary Ca:P ratio. The imbalance in the dietary Ca:P ratio was a result of feeding deboned and eviscerated fish. This investigation also highlighted potential health risks associated with the practice of feeding stored rancid proventricular oil, including the destruction of fat-soluble vitamins. It is therefore possible that oxidative degradation of vitamin D may have contributed to the development of nutritional secondary hyperparathyroidism. Subsequently, dietary recommendations for supplementary feeding of orphaned Northern Royal albatross chicks include the feeding of whole human-grade fish with an appropriate Ca:P ratio, and the exclusion of proventricular oil. These cases highlight the need for scientific input into wildlife conservation projects, as lack of appropriate nutritional advice resulted in the feeding of a nutritionally inadequate diet. Following the recommended changes in diet, no further cases of osteodystrophy have been diagnosed in hand-raised chicks in the albatross colony.

  6. Development of Experimental Myopia in Chicks in a Natural Environment

    Science.gov (United States)

    Stone, Richard A.; Cohen, Yuval; McGlinn, Alice M.; Davison, Sherrill; Casavant, Susan; Shaffer, James; Khurana, Tejvir S.; Pardue, Machelle T.; Iuvone, P. Michael

    2016-01-01

    Purpose The hypothesis that outdoor exposure might protect against myopia has generated much interest, although available data find only modest clinical efficacy. We tested the effect of outdoor rearing on form-deprivation myopia in chicks, a myopia model markedly inhibited by high-intensity indoor laboratory lighting. Methods Unilaterally goggled cohorts of White Leghorn chicks were maintained in a species-appropriate, outdoor rural setting during daylight hours to the extent permitted by weather. Control chicks were reared indoors with incandescent lighting. Besides ocular refraction and ultrasound, we determined dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) content in retina and vitreous and measured mRNA expression levels of selected clock and circadian rhythm-related genes in the retina/RPE. Results Myopia developed in the goggled eyes of all cohorts. Whereas outdoor rearing lessened myopia by 44% at 4 days, a protective effect was no longer evident at 11 days. Outdoor rearing had no consistent effect on retinal or vitreous content of dopamine or DOPAC. Conforming to prior data on form-deprivation myopia, retina and vitreous levels of DOPAC were reduced in goggled eyes. Compared with contralateral eyes, the retinal expression of clock and circadian rhythm-related genes was modestly altered in myopic eyes of chicks reared indoors or outdoors. Conclusions Outdoor rearing of chicks induces only a partial decrease of goggle-induced myopia that is not maintained, without evidence that retinal dopamine metabolism accounts for the partial myopia inhibition under these outdoor conditions. Although modest, alterations in retinal gene expression suggest that studying circadian signals might be informative for understanding refractive mechanisms. PMID:27618415

  7. Pulsation Solution to the Equation of Earth's Gravitational Field (Main Outcome)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Using d'Alembert equation as the approximation of Einstein's equation, a solution is given in this paper to the time-dependent gravitational equation of the Earth in consideration of the Earth's features, which describes the characteristics of pulsation of the Earth and the structures of spherical layers of its interior, thus providing a theoretical basis for establishing the idea of mantle pulsation.

  8. Observation of quasi-periodic pulsations in the solar flare SF 900610

    DEFF Research Database (Denmark)

    Terekhov, O.V.; Shevchenko, A.V.; Kuz'min, A.G.;

    2002-01-01

    A quasi-periodic component was found at the maximum of the X-ray light curve for the June 10, 1990 solar flare detected by the Granat observatory. The pulsation period was 143.2 +/- 0.8 s. The intensity of the pulsing component is not constant; the maximum amplitude of the pulsations is similar t...

  9. Ultracam Photometry of Pulsating Subdwarf B Stars rf B Binaries in the Edinburgh-Cape Survey

    NARCIS (Netherlands)

    Jeffery, C.S.; Aerts, C.C.; Dhillon, V.S.; Marsh, T.R.; Morales-Rueda, L.; Maxted, P.F.L.; Kilkenny, D.; O'Donoghue, D.

    2006-01-01

    High-speed multicolor photometry with ultracam promises to revolutionize the study of pulsating subdwarf B stars. As well as providing high S/N light curves with excellent temporal resolution, color amplitude ratios may be used to discriminate between different pulsation modes. In this paper we revi

  10. On the use of hot-wire anemometry in pulsating flows. A comment on 'A critical review on advanced velocity measurement techniques in pulsating flows'

    OpenAIRE

    Berson, Arganthaël; Blanc-Benon, Philippe; Comte-Bellot, Geneviève

    2010-01-01

    International audience; In their recent topical review, Nabavi and Siddiqui (Meas. Sci. Technol. 2010 21 042002) recommended the use of hot-wire anemometry for velocity measurements in pulsating flows, especially at high frequency. This recommendation is misleading. The procedures invoked by these authors are valid only for small-amplitude fluctuations, which are of little interest for pulsating flows. When large-amplitude velocity changes occur without flow reversal, new procedures for the c...

  11. Pulsation versus metallicism in Am stars as revealed by LAMOST and WASP

    CERN Document Server

    Smalley, B; Holdsworth, D L; Kurtz, D W; Murphy, S J; De Cat, P; Anderson, D R; Catanzaro, G; Cameron, A Collier; Hellier, C; Maxted, P F L; Norton, A J; Pollacco, D; Ripepi, V; West, R G; Wheatley, P J

    2016-01-01

    We present the results of a study of a large sample of A and Am stars with spectral types from LAMOST and light curves from WASP. We find that, unlike normal A stars, $\\delta$ Sct pulsations in Am stars are mostly confined to the effective temperature range 6900 $<$ $T_{\\rm eff}$ $<$ 7600 K. We find evidence that the incidence of pulsations in Am stars decreases with increasing metallicism (degree of chemical peculiarity). The maximum amplitude of the pulsations in Am stars does not appear to vary significantly with metallicism. The amplitude distributions of the principal pulsation frequencies for both A and Am stars appear very similar and agree with results obtained from Kepler photometry. We present evidence that suggests turbulent pressure is the main driving mechanism in pulsating Am stars, rather than the $\\kappa$-mechanism, which is expected to be suppressed by gravitational settling in these stars.

  12. The technology of heat transfer enhancement in channels by means of flow pulsations

    Directory of Open Access Journals (Sweden)

    Tsynaeva Anna

    2016-01-01

    Full Text Available The rate and efficiency of curing of concrete can boost when used intense heat. The work is dedicated to the development and research of technologies of intensification of heat transfer in channels by pulsations. The study was conducted by means of numerical methods based on mass and momentum conservation equations (Navier-Stokes with software Code Saturne. Verification of implemented methods and software was performed. The research of heat transfer enhancement for semicircle-shaped channel exposed to low-frequency pulsations was performed. The pulsation frequency of the flow during the study was in a range of 0…10 Hz. A significant (up to 4 times increase of turbulent kinetic energy with implementing pulsations was detected. Flow pulsations with frequency of 10 Hz results in 1.21 times increase of heat transfer coefficient.

  13. Searching for X-ray Pulsations from Neutron Stars Using NICER

    Science.gov (United States)

    Ray, Paul S.; Arzoumanian, Zaven; Bogdanov, Slavko; Bult, Peter; Chakrabarty, Deepto; Guillot, Sebastien; Kust Harding, Alice; Ho, Wynn C. G.; Lamb, Frederick K.; Mahmoodifar, Simin; Miller, M. Coleman; Strohmayer, Tod E.; Wilson-Hodge, Colleen A.; Wolff, Michael Thomas

    2017-08-01

    The Neutron Star Interior Composition Explorer (NICER) presents an exciting new capability for discovering new modulation properties of X-ray emitting neutron stars, including large area, low background, extremely precise absolute time stamps, superb low-energy response and flexible scheduling. The Pulsation Searches and Multiwavelength Coordination working group has designed a 2.5 Ms observing program to search for pulsations and characterize the modulation properties of about 30 known or suspected neutron star sources across a number of source categories. A key early goal will be to search for pulsations from millisecond pulsars that might exhibit thermal pulsations from the surface suitable for pulse profile modeling to constrain the neutron star equation of state. In addition, we will search for pulsations from transitional millisecond pulsars, isolated neutron stars, LMXBs, accretion-powered millisecond pulsars, central compact objects and other sources. We will present our science plan and initial results from the first months of the NICER mission.

  14. High frequency A-type pulsators discovered using SuperWASP

    CERN Document Server

    Holdsworth, Daniel L; Gillon, M; Clubb, K I; Southworth, J; Maxted, P F L; Anderson, D R; Barros, S C C; Cameron, A Collier; Delrez, L; Faedi, F; Haswell, C A; Hellier, C; Horne, K; Jehin, E; Norton, A J; Pollacco, D; Skillen, I; Smith, A M S; West, R G; Wheatley, P J

    2014-01-01

    We present the results of a survey using the WASP archive to search for high frequency pulsations in F-, A- and B-type stars. Over 1.5 million targets have been searched for pulsations with amplitudes greater than 0.5 millimagnitude. We identify over 350 stars which pulsate with periods less than 30 min. Spectroscopic follow-up of selected targets has enabled us to confirm 10 new rapidly oscillating Ap stars, 13 pulsating Am stars and the fastest known $\\delta$ Scuti star. We also observe stars which show pulsations in both the high-frequency domain and in the low-frequency $\\delta$ Scuti range. This work shows the power of the WASP photometric survey to find variable stars with amplitudes well below the nominal photometric precision per observation.

  15. On the effect of water film on flow-induced pulsations in closed side branches in tandem configuration

    NARCIS (Netherlands)

    Sanna, F.; Golliard, J.; Belfroid, S.P.C.

    2015-01-01

    Previous studies demonstrate that the presence of liquid strongly influences the pressure pulsation amplitudes of flow induced pulsations. In particular, in case of annular flow (thin liquid film on the walls) the pulsations can be eliminated. The present study aims at evaluating the contribution of

  16. CoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data

    CERN Document Server

    Degroote, P; Ollivier, M; Miglio, A; Debosscher, J; Cuypers, J; Briquet, M; Montalban, J; Thoul, A; Noels, A; De Cat, P; Balaguer-Nuñez, L; Maceroni, C; Ribas, I; Auvergne, M; Baglin, A; Deleuil, M; Weiss, W; Jorda, L; Baudin, F; Samadi, R

    2009-01-01

    We search for new variable B-type pulsators in the CoRoT data assembled primarily for planet detection, as part of CoRoT's Additional Programme. We aim to explore the properties of newly discovered B-type pulsators from the uninterrupted CoRoT space-based photometry and to compare them with known members of the Beta Cep and slowly pulsating B star (SPB) classes. We developed automated data analysis tools that include algorithms for jump correction, light-curve detrending, frequency detection, frequency combination search, and for frequency and period spacing searches. Besides numerous new, classical, slowly pulsating B stars, we find evidence for a new class of low-amplitude B-type pulsators between the SPB and Delta Sct instability strips, with a very broad range of frequencies and low amplitudes, as well as several slowly pulsating B stars with residual excess power at frequencies typically a factor three above their expected g-mode frequencies. The frequency data we obtained for numerous new B-type pulsato...

  17. Embryonic death and the creation of human embryonic stem cells

    OpenAIRE

    Landry, Donald W.; Zucker, Howard A.

    2004-01-01

    The creation of human embryonic stem cells through the destruction of a human embryo pits the value of a potential therapeutic tool against that of an early human life. This contest of values has resulted in a polarized debate that neglects areas of common interest and perspective. We suggest that a common ground for pursuing research on human embryonic stem cells can be found by reconsidering the death of the human embryo and by applying to this research the ethical norms of essential organ ...

  18. Embryonic death and the creation of human embryonic stem cells.

    Science.gov (United States)

    Landry, Donald W; Zucker, Howard A

    2004-11-01

    The creation of human embryonic stem cells through the destruction of a human embryo pits the value of a potential therapeutic tool against that of an early human life. This contest of values has resulted in a polarized debate that neglects areas of common interest and perspective. We suggest that a common ground for pursuing research on human embryonic stem cells can be found by reconsidering the death of the human embryo and by applying to this research the ethical norms of essential organ donation.

  19. Empirical Determination of Convection in Pulsating White Dwarfs

    Science.gov (United States)

    Provencal, Judith L.; Hermes, J. J.; Montgomery, M.; Reed, Mike; Shipman, Harry; Fraga, Luciano

    2013-02-01

    We propose high speed photometric observations of WD J1518+0658 with SOAR and the KPNO 2m as important components of a coordinated international campaign designed to survey the properties of convection in white dwarf atmospheres. Convection remains the largest source of theoretical uncertainty in our understanding of stellar physics. Asteroseismology has proven a powerful tool to attack this problem. White dwarf pulsations appear as local surface temperature variations. The extreme temperature sensitivity of convection leads to local variations in the convection zone's depth. This in turn modulates the local energy flux, producing nonsinusoidal light curves. The observed nonlinearities provide a self-consistent observational test of convection in white dwarf atmospheres. WD J1518+0658 is a member of the newly discovered class of extremely low mass white dwarf pulsators (ELMVs). ELMVs offer the opportunity to extend our investigation to unexplored regions of lower effective temperatures and surface gravities, where conditions are closer to those found in main sequence stars. High precision light curves from SOAR, combined with frequency, amplitude, and phase information provided by the KPNO 2m and the entire WET run, will allow us to recover WD J1518+0658's convective thermal response timescale.

  20. SEISMOLOGY OF A MASSIVE PULSATING HYDROGEN ATMOSPHERE WHITE DWARF

    Energy Technology Data Exchange (ETDEWEB)

    Kepler, S. O.; Pelisoli, Ingrid; Pecanha, Viviane; Costa, J. E. S. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, RS (Brazil); Fraga, Luciano [Southern Observatory for Astrophysical Research, Casilla 603, La Serena (Chile); Hermes, J. J.; Winget, D. E.; Castanheira, Barbara [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712-1083 (United States); Corsico, A. H.; Romero, A. D.; Althaus, Leandro [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata (Argentina); Kleinman, S. J.; Nitta, A. [Gemini Observatory, Northern Operations Center, 670 North A' ohoku Place, Hilo, HI 96720 (United States); Koester, D. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Kiel, D-24098 Kiel (Germany); Kuelebi, Baybars [Institut de Ciencies de L' Espai, Universitat Autonoma de Barcelon and Institute for Space Studies of Catalonia, c/Gran Capita 2-4, Edif. Nexus 104, E-08034 Barcelona (Spain); Jordan, Stefan [Astronomisches Rechen-Institut, ZAH, Moenchhofstr. 12-14, D-69120 Heidelberg (Germany); Kanaan, Antonio, E-mail: kepler@if.ufrgs.br [Departamento de Fisica, Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil)

    2012-10-01

    We report our observations of the new pulsating hydrogen atmosphere white dwarf SDSS J132350.28+010304.22. We discovered periodic photometric variations in frequency and amplitude that are commensurate with nonradial g-mode pulsations in ZZ Ceti stars. This, along with estimates for the star's temperature and gravity, establishes it as a massive ZZ Ceti star. We used time-series photometric observations with the 4.1 m SOAR Telescope, complemented by contemporary McDonald Observatory 2.1 m data, to discover the photometric variability. The light curve of SDSS J132350.28+010304.22 shows at least nine detectable frequencies. We used these frequencies to make an asteroseismic determination of the total mass and effective temperature of the star: M{sub *} = 0.88 {+-} 0.02 M{sub Sun} and T{sub eff} = 12, 100 {+-} 140 K. These values are consistent with those derived from the optical spectra and photometric colors.

  1. Pulsational instability of complex charge-fluctuating magnetized turbulent astroclouds

    Science.gov (United States)

    Karmakar, Pralay Kumar; Haloi, Archana

    2017-09-01

    We develop a theoretic model to study the linear stability behaviour of pulsational (gravito-electrostatic) mode in a self-gravitating, magnetized, collisional, turbulent and unbounded dust molecular cloud (DMC). The analytic model consists of lighter electrons and ions; and massive charged dust grains with partial ionization over the geometrically infinite extension. The semi-empirically obtained Larson logatropic equation of state, correlating all the thermo-turbo-magnetic pressures concurrently, is included afresh to model the constituent fluid turbulence pressures arising because of multiple randomized aperiodic flow scales of space and time. A linear normal mode analysis over the slightly perturbed composite cloud, relative to the defined homogeneous hydrostatic equilibrium, results in a unique mathematical construct of generalized polynomial (octic) dispersion relation with different coefficients sensitively dependent upon the diversified equilibrium cloud parameters. The main features of the modified pulsational mode dynamics are numerically explored over a commodious window of parametric values. It is shown and established that the grain mass introduces a dispersive stabilizing effect to the mode (with enhancement in phase speed), and vice-versa. A spatiotemporal illustrative tapestry is also portrayed for further confirmation of the dispersive mode with sporadic properties. The tentative application of our findings in different space and astrophysical circumstances is briefly outlined.

  2. Studies of the Long Secondary Periods in Pulsating Red Giants

    CERN Document Server

    Percy, John R

    2016-01-01

    We have used systematic, sustained visual observations from the AAVSO International Database, and the AAVSO time-series analysis package VSTAR to study the unexplained "long secondary periods" (LSPs) in 27 pulsating red giants. In our sample, the LSPs range from 479 to 2967 days, and are on average 8.1 +/- 1.3 times the pulsation period. There is no evidence for more than one LSP in each star. In stars with both the fundamental and first overtone radial period present, the LSP is more often about 10 times the latter. The visual amplitudes of the LSPs are typically 0.1 magnitude and do not correlate with the LSP. The phase curves tend to be sinusoidal, but at least two are sawtooth. The LSPs are stable, within their errors, over the timespan of our data, which is typically 25,000 days. The amplitudes, however, vary by up to a factor of two or more on a timescale of roughly 20-30 LSPs. There is no obvious difference between the behavior of the carbon (C) stars and the normal oxygen (M) stars. Previous multicolo...

  3. Computer modeling of capillary flow with superimposed pulsations

    Science.gov (United States)

    Yaganova, A. E.; Marfin, E. A.

    2016-11-01

    Increasing efficiency of methods of oil production can be achieved by the influence of elastic vibrations. It is a well-known fact that shift viscosity of oil changes under the effect of elastic vibrations. This change depends on properties of the oil and exposure mode. Existing approaches to the research of the way wave exposure impacts on viscosity are based on measuring it after the processing. This article concerns development of methods to measure viscosity of liquid right during its exposure to elastic vibrations. The suggested approach is based on combining numerical and natural experiments. We investigated the pulsating flow of viscid liquid in a capillary numerically in this article. We received allocations of fields of average velocity and pressure in a capillary. It is demonstrated that imposed pulsations in a capillary do not impact on hydrodynamics of the flow. We offered the scheme of an experimental installation for a research of the impact that wave exposure has on the viscosity of liquids. The installation is based on a capillary viscometer.

  4. A spectroscopic study of the hybrid pulsator Gamma Pegasi

    CERN Document Server

    Pandey, C P; Briquet, M; Jayakumar, K; Bisht, S; Sanwal, B B

    2011-01-01

    The recent detection of both pressure and high-order gravity modes in the classical B-type pulsator Gamma Pegasi offers promising prospects for probing its internal structure through seismic studies. To aid further modelling of this star, we present the results of a detailed NLTE abundance analysis based on a large number of time-resolved, high-quality spectra. A chemical composition typical of nearby B-type stars is found. The hybrid nature of this star is consistent with its location in the overlapping region of the instability strips for beta Cephei and slowly pulsating B stars computed using OP opacity tables, although OPAL calculations may also be compatible with the observations once the uncertainties in the stellar parameters and the current limitations of the stability calculations are taken into account. The two known frequencies f1 = 6.58974 and f2 = 0.68241 c/d are detected in the spectroscopic time series. A mode identification is attempted for the low-frequency signal, which can be associated to ...

  5. Pulsation models for the roAp star HD 134214

    CERN Document Server

    Saio, H; Weiss, W W; Matthews, J M; Ryabchikova, T

    2011-01-01

    Precise time-series photometry with the MOST satellite has led to identification of 10 pulsation frequencies in the rapidly oscillating Ap (roAp) star HD 134214. We have fitted the observed frequencies with theoretical frequencies of axisymmetric modes in a grid of stellar models with dipole magnetic fields. We find that, among models with a standard composition of $(X,Z) = (0.70,0.02)$ and with suppressed convection, eigenfrequencies of a $1.65\\,{\\rm M}_\\odot$ model with $\\log T_{\\rm eff} = 3.858$ and a polar magnetic field strength of 4.1kG agree best with the observed frequencies. We identify the observed pulsation frequency with the largest amplitude as a deformed dipole ($\\ell = 1$) mode, and the four next-largest-amplitude frequencies as deformed $\\ell = 2$ modes. These modes have a radial quasi-node in the outermost atmospheric layers ($\\tau \\sim 10^{-3}$). Although the model frequencies agree roughly with observed ones, they are all above the acoustic cut-off frequency for the model atmosphere and hen...

  6. Axions and the pulsation periods of variable white dwarfs revisited

    CERN Document Server

    Isern, J; Althaus, L G; Córsico, A H

    2010-01-01

    Axions are the natural consequence of the introduction of the Peccei-Quinn symmetry to solve the strong CP problem. All the efforts to detect such elusive particles have failed up to now. Nevertheless, it has been recently shown that the luminosity function of white dwarfs is best fitted if axions with a mass of a few meV are included in the evolutionary calculations. Our aim is to show that variable white dwarfs can provide additional and independent evidence about the existence of axions. The evolution of a white dwarf is a slow cooling process that translates into a secular increase of the pulsation periods of some variable white dwarfs, the so-called DAV and DBV types. Since axions can freely escape from such stars, their existence would increase the cooling rate and, consequently, the rate of change of the periods as compared with the standard ones. The present values of the rate of change of the pulsation period of G117-B15A are compatible with the existence of axions with the masses suggested by the lu...

  7. Pulsations of rapidly rotating stars: I. The ACOR numerical code

    CERN Document Server

    Ouazzani, Rhita-Maria; Reese, Daniel

    2012-01-01

    Very high precision seismic space missions such as CoRoT and Kepler provide the means of testing the modeling of transport processes in stellar interiors. For some stars, such as solar-like and red giant stars, a rotational splitting is measured. However, in order to fully exploit these splittings and constrain the rotation profile, one needs to be able to calculate them accurately. For some other stars, such as $\\delta$ Scuti and Be stars, for instance, the observed pulsation spectra are modified by rotation to such an extent that a perturbative treatment of the effects of rotation is no longer valid. We present here a new two-dimensional non-perturbative code, called ACOR (\\textit{Adiabatic Code of Oscillation including Rotation}) which allows us to compute adiabatic non-radial pulsations of rotating stars, without making any assumptions on the sphericity of the star, the fluid properties (i.e. baroclinicity) or the rotation profile. The 2D non-perturbative calculations fully take into account the centrifug...

  8. $\\gamma$ Doradus Pulsations in the Eclipsing Binary Star KIC 6048106

    CERN Document Server

    Lee, Jae Woo

    2016-01-01

    We present the ${\\it Kepler}$ photometry of KIC 6048106 exhibiting O'Connell effect and multiperiodic pulsations. Including a starspot on either of the components, light-curve synthesis indicates that this system is a semi-detached Algol with a mass ratio of 0.211, an orbital inclination of 73.9 deg, and a large temperature difference of 2,534 K. To examine in detail both spot variations and pulsations, we separately analyzed the {\\it Kepler} time-series data at the interval of an orbital period by an iterative way. The results reveal that the variable asymmetries of the light maxima can be interpreted as the changes of a magnetic cool spot on the secondary component with time. Multiple frequency analyses were performed in the outside-eclipse light residuals after removal of the binarity effects from the observed {\\it Kepler} data. We detected 30 frequencies with signal to noise amplitude ratios larger than 4.0, of which six ($f_2$--$f_6$ and $f_{10}$) can be identified as high-order (17 $\\le n \\le$ 25) low-d...

  9. Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227

    CERN Document Server

    Guo, Zhao; Fuller, Jim

    2016-01-01

    KIC 3230227 is a short period ($P\\approx 7.0$ days) eclipsing binary with a very eccentric orbit ($e=0.6$). From combined analysis of radial velocities and {\\it Kepler} light curves, this system is found to be composed of two A-type stars, with masses of $M_1=1.84\\pm 0.18M_{\\odot}$, $M_2=1.73\\pm 0.17M_{\\odot}$ and radii of $R_1=2.01\\pm 0.09R_{\\odot}$, $R_2=1.68\\pm 0.08 R_{\\odot}$ for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than ten pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for $l=2, m=-2$ prograde modes.

  10. Pressure pulsation in roller pumps: a validated lumped parameter model.

    Science.gov (United States)

    Moscato, Francesco; Colacino, Francesco M; Arabia, Maurizio; Danieli, Guido A

    2008-11-01

    During open-heart surgery roller pumps are often used to keep the circulation of blood through the patient body. They present numerous key features, but they suffer from several limitations: (a) they normally deliver uncontrolled pulsatile inlet and outlet pressure; (b) blood damage appears to be more than that encountered with centrifugal pumps. A lumped parameter mathematical model of a roller pump (Sarns 7000, Terumo CVS, Ann Arbor, MI, USA) was developed to dynamically simulate pressures at the pump inlet and outlet in order to clarify the uncontrolled pulsation mechanism. Inlet and outlet pressures obtained by the mathematical model have been compared with those measured in various operating conditions: different rollers' rotating speed, different tube occlusion rates, and different clamping degree at the pump inlet and outlet. Model results agree with measured pressure waveforms, whose oscillations are generated by the tube compression/release mechanism during the rollers' engaging and disengaging phases. Average Euclidean Error (AEE) was 20mmHg and 33mmHg for inlet and outlet pressure estimates, respectively. The normalized AEE never exceeded 0.16. The developed model can be exploited for designing roller pumps with improved performances aimed at reducing the undesired pressure pulsation.

  11. Spectrophotometry of pulsating stars at Oukaimeden Observatory in Morocco

    Science.gov (United States)

    Benhida, Abdelmjid; sefyani, Fouad; de France, Thibault; Elashab, Sana; Zohra Belharcha, fatim; Gillet, Denis; Mathias, phillipe; Daassou, Ahmed; Lazrek, Mohamed; Benkhaldoun, Zouhair

    2015-08-01

    Location of modern observatories requires high sky quality: good weather, isolated site to avoid any pollution, high altitude for a better transparency and to reduce temperature gradients, the main source of atmospheric turbulence. With an altitude of 2750m, the region of Oukaimeden in Morocco (longitude: 7°52'052" West, latitude: 3°112032" North) meets most of these criteriaWith its 10'' and 14'' dedicated telescopes operating in remote control modes that combines high precision photometry and high resolution spectroscopy (spectrograph Eshell of R~12000 resolution over a wide spectral range), the universitary observatory of Oukaimeden (code J43) aims to develop new thematics in addition to present science. In particular, through this instrumentation, we aim to develop the field of pulsating stars, especially the atmospheric dynamics of high amplitude pulsators such as RR Lyrae and RV Tauri star, in order to establish new models of the mechanical and thermal behaviour of their atmospheres (shock waves, relaxation time, energy loss...).In this work we will first describe our measuring instruments, and then analyze spectra and photometric curves of RR Lyrae star obtained during the maximum of the Blazhko effect.

  12. Characterization of ultra low frequency (ULF pulsations and the investigation of their possible source

    Directory of Open Access Journals (Sweden)

    S. H. Mthembu

    2009-08-01

    Full Text Available In this paper we present the results from the observation of ultra low frequency (ULF pulsations in the Doppler velocity data from SuperDARN HF radar located at Goose Bay (61.94° N, 23.02° E, geomagnetic. Fourier spectral techniques were used to determine the spectral content of the data and the results show Pc 5 ULF pulsations (with a frequency range of 1 to 4 mHz where the magnetic field lines were oscillating at discrete frequencies of about 1.3 and 1.9 mHz. These pulsations are classified as field lines resonance (FLR since the 1.9 mHz component exhibited an enhancement in amplitude with an associated phase change of approximately 180° across a resonance latitude of 71.3°. The spatial and temporal structure of the ULF pulsations was examined by investigating their instantaneous amplitude which was calculated as the amplitude of the analytic signal. The results presented a full field of view which exhibit pulsations activity simultaneously from all beams. This representation shows that the peak amplitude of the 1.9 mHz component was observed over the longitudinal range of 13°. The temporal structure of the pulsations was investigated from the evolution of the 1.9 mHz component and the results showed that the ULF pulsations had a duration of about 1 h. Wavelet analysis was used to investigate solar wind as a probable source of the observed ULF pulsations. The time delay compared well with the solar wind travel time estimates and the results suggest a possible link between the solar wind and the observed pulsations. The sudden change in dynamic pressure also proved to be a possible source of the observed ULF pulsations.

  13. Ventricular dilation and elevated aqueductal pulsations in a new experimental model of communicating hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Wagshul, M.; Smith, S.; Wagshul, M.; McAllister, J.P.; Rashid, S.; Li, J.; Egnor, M.R.; Walker, M.L.; Yu, M.; Smith, S.D.; Zhang, G.; Chen, J.J.; Beneveniste, H.

    2009-03-01

    In communicating hydrocephalus (CH), explanations for the symptoms and clear-cut effective treatments remain elusive. Pulsatile flow through the cerebral aqueduct is often significantly elevated, but a clear link between abnormal pulsations and ventriculomegaly has yet to be identified. We sought to demonstrate measurement of pulsatile aqueductal flow of CSF in the rat, and to characterize the temporal changes in CSF pulsations in a new model of CH. Hydrocephalus was induced by injection of kaolin into the basal cisterns of adult rats (n = 18). Ventricular volume and aqueductal pulsations were measured on a 9.4 T MRI over a one month period. Half of the animals developed ventricular dilation, with increased ventricular volume and pulsations as early as one day post-induction, and marked chronic elevations compared to intact controls (volume: 130.15 {+-} 83.21 {mu}l vs. 15.52 {+-} 2.00 {mu}l; pulsations: 114.51 nl {+-} 106.29 vs. 0.72 {+-} 0.13 nl). Similar to the clinical presentation, the relationship between ventricular size and pulsations was quite variable. However, the pulsation time-course revealed two distinct sub-types of hydrocephalic animals: those with markedly elevated pulsations which persisted over time, and those with mildly elevated pulsations which returned to near normal levels after one week. These groups were associated with severe and mild ventriculomegaly respectively. Thus, aqueductal flow can be measured in the rat using high-field MRI and basal cistern-induced CH is associated with an immediate change in CSF pulsatility. At the same time, our results highlight the complex nature of aqueductal pulsation and its relationship to ventricular dilation.

  14. The first evidence for multiple pulsation axes: a new rapidly oscillating Ap star in the Kepler field, KIC 10195926

    DEFF Research Database (Denmark)

    Kurtz, Donald W.; Cunha, Margarida S.; Saio, H.;

    2011-01-01

    model that these two modes cannot have the same axis of pulsation. This is the first time for any pulsating star that evidence has been found for separate pulsation axes for different modes. The two modes are separated in frequency by 55 μHz, which we model as the large separation. The star is an α2 CVn...... to these values that reproduces the rotational variations of the two obliquely pulsating modes with different pulsation axes. The star shows overabundances of the rare earth elements, but these are not as extreme as most other roAp stars. The spectrum is variable with rotation, indicating surface abundance...

  15. Peculiar variations of white dwarf pulsation frequencies and maestro

    Science.gov (United States)

    Dalessio, James Ruland

    In Part I we report on variations of the normal mode frequencies of the pulsating DB white dwarfs EC 20058-5234 and KIC 8626021 and the pulsating DA white dwarf GD 66. The observations of EC 20058-5234 and KIC 8626021 were motivated by the possibility of measuring the plasmon neutrino production rate of a white dwarf, while the observations of GD 66 were part of a white dwarf pulsation timing based planet search. We announce the discovery of periodic and quasi-periodic variations of multiple normal mode frequencies that cannot be due to the presence of planetary companions. We note the possible signature of a planetary companion to EC 20058-5234 and show that GD 66 cannot have a planet in a several AU orbit down to half a Jupiter mass. We also announce the discovery of secular variations of the normal mode frequencies of all three stars that are inconsistent with cooling alone. Importantly, the rates of period change of several modes of KIC 8626021 are consistent with evolutionary cooling, but are not yet statistically significant. These modes offer the best possibility of measuring the neutrino production rate in a white dwarf. We also observe periodic and secular variations in the frequency of a combination mode that exactly matches the variations predicted by the parent modes, strong observational evidence that combination modes are created by the convection zone and are not normal modes. Periodic variations in the amplitudes of many of these modes is also noted. We hypothesize that these frequency variations are caused by complex variations of the magnetic field strength and geometry, analogous to behavior observed in the Sun. In Part II we describe the MAESTRO software framework and the MAESTRO REDUCE algorithm. MAESTRO is a collection of astronomy specific MatLab software developed by the Whole Earth Telescope. REDUCE is an an algorithm that can extract the brightness of stars on a set of CCD images with minimal configuration and human interaction. The key to

  16. Soft X-Ray Pulsations in Solar Flares

    Science.gov (United States)

    Simões, P. J. A.; Hudson, H. S.; Fletcher, L.

    2015-12-01

    The soft X-ray emissions ( hν>1.5 keV) of solar flares mainly come from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy, although the overwhelming bulk of the total flare energy goes elsewhere. Recently Dolla et al. ( Astrophys. J. Lett. 749, L16, 2012) noted quasi-periodic pulsations (QPP) in the soft X-ray signature of the X-class flare SOL2011-02-15, as observed by the standard photometric data from the GOES ( Geostationary Operational Environmental Satellite) spacecraft. In this article we analyse the suitability of the GOES data for this type of analysis and find them to be generally valuable after September, 2010 (GOES-15). We then extend the result of Dolla et al. to a complete list of X-class flares from Cycle 24 and show that most of them (80 %) display QPPs in the impulsive phase. The pulsations show up cleanly in both channels of the GOES data, making use of time-series of irradiance differences (the digital time derivative on the 2-s sampling). We deploy different techniques to characterise the periodicity of GOES pulsations, considering the red-noise properties of the flare signals, finding a range of characteristic time scales of the QPPs for each event, but usually with no strong signature of a single period dominating in the power spectrum. The QPP may also appear on somewhat longer time scales during the later gradual phase, possibly with a greater tendency towards coherence, but the sampling noise in GOES difference data for high irradiance values (X-class flares) makes these more uncertain. We show that there is minimal phase difference between the differenced GOES energy channels, or between them and the hard X-ray variations on short time scales. During the impulsive phase, the footpoints of the newly forming flare loops may also contribute to the observed soft X-ray variations.

  17. Embryonic chicken transplantation is a promising model for studying the invasive behaviour of melanoma cells.

    Directory of Open Access Journals (Sweden)

    Aparna eJayachandran

    2015-02-01

    Full Text Available Epithelial-to-mesenchymal transition is a hallmark event in the metastatic cascade conferring invasive ability to tumor cells. There are ongoing efforts to replicate the physiological events occurring during mobilization of tumor cells in model systems. However, few systems are able to capture these complex in vivo events. The embryonic chicken transplantation model has emerged as a useful system to assess melanoma cells including functions that are relevant to the metastatic process, namely invasion and plasticity. The chicken embryo represents an accessible and economical 3-dimensional in vivo model for investigating melanoma cell invasion as it exploits the ancestral relationship between melanoma and its precursor neural crest cells. We describe a methodology which enables the interrogation of melanoma cell motility within the developing avian embryo. This model involves the injection of melanoma cells into the neural tube of chicken embryos. Melanoma cells are labelled using fluorescent tracker dye, Vybrant DiO, then cultured as hanging drops for 24 hours to aggregate the cells. Groups of approximately 700 cells are placed into the neural tube of chicken embryos prior to the onset of neural crest migration at the hindbrain level (embryonic day 1.5 or trunk level (embryonic day 2.5. Chick embryos are reincubated and analysed after 48 hours for the location of melanoma cells using fluorescent microscopy on whole mounts and cross-sections of the embryos. Using this system, we compared the in vivo invasive behavior of epithelial-like and mesenchymal-like melanoma cells. We report that the developing embryonic microenvironment confers motile abilities to both types of melanoma cells. Hence the embryonic chicken transplantation model has potential to become a valuable tool for in vivo melanoma invasion studies. Importantly, it may provide novel insights into and reveal previously unknown mediators of the metastatic steps of invasion and

  18. Glutamine synthetase localization in cortisol-induced chick embryo retinas

    OpenAIRE

    1980-01-01

    We report here for the first time, in chick retina, Muller cell localization of glutamine synthetase (GS) activity by an immunohistochemical technique, in agreement with previous reports of glial localization of this enzyme in rat brain and retina. Age- dependent changes in the endogenous enzyme activity as well as cortisol- induced changes in GS activity, both in ovo and in vitro, measured biochemically, reflect the changes observed by staining.

  19. Interactions among dietary boron, molybdenum, and magnesium in the chick

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, C.D.; Nielsen, F.H.

    1986-03-01

    The authors have previously reported that dietary B affects plasma Mo concentrations in chicks fed inadequate levels of Mg and cholecalciferol (vit. D/sub 3/). Because of this finding, they studied the effect of dietary Mo and Mg on the signs of B deficiency in vit. D/sub 3/ deprived chicks. In a fully crossed, 2 x 2 x 2 factorially arranged experiment, day-old cockerel chicks (19 per group) were fed a ground corn-casein-corn oil based diet (containing 0.850 mg B, 0.319 mg Mo, and 125 IU vit. D/sub 3//kg) supplemented with B at 0 or 3 mg/kg, Mo at 0 or 20 mg/kg, and Mg at 300 or 500 mg/kg. After four weeks, B deprivation depressed growth and elevated the plasma glucose and the brain wt/body wt ratio. Low dietary Mo elevated the heart wt/body wt ratio. An interaction between B and Mg affected hemoglobin and plasma alkaline phosphatase and an interaction between B and Mo affected the heart wt/body wt and liver wt/body wt ratios. Mg deficiency gave usual signs including depressed growth, plasma alkaline phosphatase, glucose, and spleen and liver wt/body wt ratios and elevated hematocrit and brain wt/body wt ratio. The findings suggest that physiological levels of Mg and Mo affect B metabolism. The effects of low dietary Mo on vit. D/sub 3/ and/or Mg-deficient chicks needs to be elucidated.

  20. Retinal venous pulsation: Expanding our understanding and use of this enigmatic phenomenon.

    Science.gov (United States)

    Morgan, William H; Hazelton, Martin L; Yu, Dao-Yi

    2016-11-01

    Retinal vein pulsation was first noted soon after the invention of the ophthalmoscope 170 years ago and was seen to change with cerebrospinal fluid pressure (CSFP) variation in the 1920s. The classical explanation for vein pulsation was that the cardiac cycle induced systolic peak in intraocular pressure (IOP) tended to intermittently collapse the retinal vein close to its exit in the central optic disk, causing pulsation to be counter-phase to IOP. Recently, improved ophthalmodynamometry and video recording techniques have allowed us to explore the fundamentals of retinal vein pulsation. This demonstrates that retinal venous collapse is in phase with both IOP and CSFP diastole, indicating the dependence upon CSFP pulse. We describe in some detail the mathematical and physical models of Starling resistors and how their results can be applied to understand the physiology of retinal vein pulsation. We discuss various techniques for measuring retinal venous pulsation, including a novel modified photo-plethysmographic technique developed in our laboratory. With these techniques, non-invasive measurement of CSFP is beginning to look feasible. Venous pulsation properties also have significant prognostic value in predicting long-term outcomes for both glaucoma and central retinal vein occlusion, as well as utility in other retinal vasculopathies and orbital disease. We demonstrate the potential use of modified photo-plethysmographic images in assessing these various disorders. A revised understanding of retinal vein pulse wave transmission along with improved measurement techniques may generate useful clinical tools for assessing these disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Coupled pulsating and cellular structure in the propagation of globally planar detonations in free space

    Energy Technology Data Exchange (ETDEWEB)

    Han, Wenhu [Center for Combustion Energy, Tsinghua University, Beijing 100084 (China); Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Gao, Yang, E-mail: gaoyang-00@mails.tsinghua.edu.cn [Center for Combustion Energy, Tsinghua University, Beijing 100084 (China); Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Wang, Cheng [Beijing Institute of Technology, Beijing 100081 (China); Law, Chung K. [Center for Combustion Energy, Tsinghua University, Beijing 100084 (China); Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-10-15

    The globally planar detonation in free space is numerically simulated, with particular interest to understand and quantify the emergence and evolution of the one-dimensional pulsating instability and the two-dimensional cellular structure which is inherently also affected by pulsating instability. It is found that the pulsation includes three stages: rapid decay of the overdrive, approach to the Chapman-Jouguet state and emergence of weak pulsations, and the formation of strong pulsations; while evolution of the cellular structure also exhibits distinct behavior at these three stages: no cell formation, formation of small-scale, irregular cells, and formation of regular cells of a larger scale. Furthermore, the average shock pressure in the detonation front consists of fine-scale oscillations reflecting the collision dynamics of the triple-shock structure and large-scale oscillations affected by the global pulsation. The common stages of evolution between the cellular structure and the pulsating behavior, as well as the existence of shock-front pressure oscillation, suggest highly correlated mechanisms between them. Detonations with period doubling, period quadrupling, and chaotic amplitudes were also observed and studied for progressively increasing activation energies.

  2. Spatio-temporal dynamics of sources of hard X-ray pulsations in solar flares

    CERN Document Server

    Kuznetsov, S A; Morgachev, A S; Struminsky, A B

    2016-01-01

    We present systematic analysis of spatio-temporal evolution of sources of hard X-ray (HXR) pulsations in solar flares. We concentrate on disk flares whose impulsive phase are accompanied by a series of more than three peaks (pulsations) of HXR emission detected in the RHESSI 50-100 keV channel with 4-second cadence. 29 such flares observed from February 2002 to June 2015 with time differences between successive peaks of 8-270 s are studied. The main observational result is that sources of HXR pulsations in all flares are not stationary, they demonstrate apparent displacements from pulsation to pulsation. The flares can be subdivided into two groups depending on character of dynamics of HXR sources. The group-1 consists of 16 flares (55%) with systematic dynamics of HXR sources from pulsation to pulsation with respect to a magnetic polarity inversion line (MPIL), which has simple extended trace on the photosphere. The group-2 consists of 13 flares (45%) with more chaotic displacements of HXR sources with respe...

  3. Propagation and source of Pc5 frequency range pulsation at cusp latitude

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Two induction magnetometers have been installed at Chinese Zhongshan Station and Australia Davis Station, Antarctica respectively. We adopt the cross-spectral analysis technique to analyze the data of the two induction magnetometers, in June, September, December 1996 and March 1997, and to investigate Pc5 frequency range pulsation (150 600 s) occurrence and propagation in cusp latitude. The results are summarized as follows: At Zhongshan-Davis Station, the magnetic pulsations in Pc5 frequency band can occurs over a wide time, but more frequently at pre local magnetic noon and pre local magnetic midnight. The Pc5 pulsations have no significant seasonal variation in the amplitude, occurrence and propagation. The amplitude has a small peak at pre local magnetic noon and large value sometimes at pre local magnetic midnight. In daytime, the Pc5 pulsations propagate westward in morning and eastward in afternoon, and reversal at local magnetic noon. In nighttime, the Pc5 pulsations propagate westward before 20:00 MLT and eastward after 20:00 MLT. Near dusk time, the Pc5 pulsations propagate irregularly. These characteristics indicate that the Pc5 pulsations have different source at different local magnetic time.

  4. GW Librae: a unique laboratory for pulsations in an accreting white dwarf

    Science.gov (United States)

    Toloza, O.; Gänsicke, B. T.; Hermes, J. J.; Townsley, D. M.; Schreiber, M. R.; Szkody, P.; Pala, A.; Beuermann, K.; Bildsten, L.; Breedt, E.; Cook, M.; Godon, P.; Henden, A. A.; Hubeny, I.; Knigge, C.; Long, K. S.; Marsh, T. R.; de Martino, D.; Mukadam, A. S.; Myers, G.; Nelson, P.; Oksanen, A.; Patterson, J.; Sion, E. M.; Zorotovic, M.

    2016-07-01

    Non-radial pulsations have been identified in a number of accreting white dwarfs in cataclysmic variables. These stars offer insight into the excitation of pulsation modes in atmospheres with mixed compositions of hydrogen, helium, and metals, and the response of these modes to changes in the white dwarf temperature. Among all pulsating cataclysmic variable white dwarfs, GW Librae stands out by having a well-established observational record of three independent pulsation modes that disappeared when the white dwarf temperature rose dramatically following its 2007 accretion outburst. Our analysis of Hubble Space Telescope (HST) ultraviolet spectroscopy taken in 2002, 2010, and 2011, showed that pulsations produce variations in the white dwarf effective temperature as predicted by theory. Additionally in 2013 May, we obtained new HST/Cosmic Origin Spectrograph ultraviolet observations that displayed unexpected behaviour: besides showing variability at ≃275 s, which is close to the post-outburst pulsations detected with HST in 2010 and 2011, the white dwarf exhibits high-amplitude variability on an ≃4.4 h time-scale. We demonstrate that this variability is produced by an increase of the temperature of a region on white dwarf covering up to ≃30 per cent of the visible white dwarf surface. We argue against a short-lived accretion episode as the explanation of such heating, and discuss this event in the context of non-radial pulsations on a rapidly rotating star.

  5. Ultra-fast magnetic resonance encephalography of physiological brain activity - Glymphatic pulsation mechanisms?

    Science.gov (United States)

    Kiviniemi, Vesa; Wang, Xindi; Korhonen, Vesa; Keinänen, Tuija; Tuovinen, Timo; Autio, Joonas; LeVan, Pierre; Keilholz, Shella; Zang, Yu-Feng; Hennig, Jürgen; Nedergaard, Maiken

    2016-06-01

    The theory on the glymphatic convection mechanism of cerebrospinal fluid holds that cardiac pulsations in part pump cerebrospinal fluid from the peri-arterial spaces through the extracellular tissue into the peri-venous spaces facilitated by aquaporin water channels. Since cardiac pulses cannot be the sole mechanism of glymphatic propulsion, we searched for additional cerebrospinal fluid pulsations in the human brain with ultra-fast magnetic resonance encephalography. We detected three types of physiological mechanisms affecting cerebral cerebrospinal fluid pulsations: cardiac, respiratory, and very low frequency pulsations. The cardiac pulsations induce a negative magnetic resonance encephalography signal change in peri-arterial regions that extends centrifugally and covers the brain in ≈1 Hz cycles. The respiratory ≈0.3 Hz pulsations are centripetal periodical pulses that occur dominantly in peri-venous areas. The third type of pulsation was very low frequency (VLF 0.001-0.023 Hz) and low frequency (LF 0.023-0.73 Hz) waves that both propagate with unique spatiotemporal patterns. Our findings using critically sampled magnetic resonance encephalography open a new view into cerebral fluid dynamics. Since glymphatic system failure may precede protein accumulations in diseases such as Alzheimer's dementia, this methodological advance offers a novel approach to image brain fluid dynamics that potentially can enable early detection and intervention in neurodegenerative diseases.

  6. [Evaluation of Antilles fish ciguatoxicity by mouse and chick bioassays].

    Science.gov (United States)

    Pottier, I; Vernoux, J P

    2003-03-01

    Ciguatera is a common seafood poisoning in Western Atlantic and French West Indies. Ciguatera fish poisoning in the Caribbean is a public health problem. A toxicological study was carried out on 178 Caribbean fish specimens (26 species) captured off Guadeloupe and Saint Barthelemy between 1993 and 1999. The mouse bioassay and the chick feeding test were used to control fish edibility. Ciguatoxins presence was assumed when symptomatology was typical of ciguatera in mouse and chick. Fishes were classified in three groups: non toxic fish (edible), low toxic fish (not edible) and toxic fish (not edible). 75% of fishes were non toxic. Toxic fish specimens belonged to four families of high trophic level carnivores: Carangidae, Lutjanidae, Serranidae et Sphyraenidae. Percentages of toxic fishes to humans reached 55% for Caranx latus and 33% for Caranx bartholomaei and Caranx lugubris. Only a significant correlation between weight and toxicity was only found for C. latus and snappers. Small carnivorous groupers (Serranidae) were also toxic. Atoxic fish species were (a) pelagic fish (Coryphaena hippurus, Auxis thazard and Euthynnus pelamis), (b) invertebrates feeders (Malacanthus plumieri, Balistes vetula), (c) small high-risk fish or (d) fish of edible benthic fish families. Liver of four fishes (Mycteroperca venenosa, Caranx bartholomaei, Seriola rivoliana, Gymnothorax funebris) contained ciguatoxins at a significant level although their flesh was safe. This study confirms the usefulness of mouse and chick bioassays for sanitary control of fish.

  7. Central administration of neuromedin U suppresses food intake in chicks.

    Science.gov (United States)

    Kamisoyama, Hiroshi; Honda, Kazuhisa; Saneyasu, Takaoki; Sugahara, Kunio; Hasegawa, Shin

    2007-06-08

    The appetite-suppressive action of brain-gut peptides is similar in both chickens and mammals. In mammals, the brain-gut peptide neuromedin U (NMU) suppresses food intake via hypothalamic neuropeptides, corticotropin-releasing factor (CRF), oxytocin, and arginine-vasopressin. In chickens, central administration of CRF, oxytocin, or arginine-vasotocin (AVT, a nonmammalian equivalent of arginine-vasopressin) suppresses food intake. However, the anorexigenic action of NMU in chickens has not yet been identified. In the present study, we analyzed the effects of the central administration of NMU on food intake and hypothalamic mRNA levels of CRF, AVT and mesotocin (a nonmammalian equivalent of oxytocin) in chicks. Intracerebroventricular administration of NMU in chicks significantly suppressed food intake and induced wing-flapping behavior. NMU also significantly upregulated mRNA expression of CRF and AVT, but did not influence mRNA expression of mesotocin in the hypothalamus. These results suggest that NMU functions as an appetite-suppressive peptide via CRF and AVT in the central nervous system in chicks.

  8. Excess caffeine exposure impairs eye development during chick embryogenesis

    Science.gov (United States)

    Ma, Zheng-lai; Wang, Guang; Cheng, Xin; Chuai, Manli; Kurihara, Hiroshi; Lee, Kenneth Ka Ho; Yang, Xuesong

    2014-01-01

    Caffeine has been an integral component of our diet and medicines for centuries. It is now known that over consumption of caffeine has detrimental effects on our health, and also disrupts normal foetal development in pregnant mothers. In this study, we investigated the potential teratogenic effect of caffeine over-exposure on eye development in the early chick embryo. Firstly, we demonstrated that caffeine exposure caused chick embryos to develop asymmetrical microphthalmia and induced the orbital bone to develop abnormally. Secondly, caffeine exposure perturbed Pax6 expression in the retina of the developing eye. In addition, it perturbed the migration of HNK-1+ cranial neural crest cells. Pax6 is an important gene that regulates eye development, so altering the expression of this gene might be the cause for the abnormal eye development. Thirdly, we found that reactive oxygen species (ROS) production was significantly increased in eye tissues following caffeine treatment, and that the addition of anti-oxidant vitamin C could rescue the eyes from developing abnormally in the presence of caffeine. This suggests that excess ROS induced by caffeine is one of the mechanisms involved in the teratogenic alterations observed in the eye during embryogenesis. In sum, our experiments in the chick embryo demonstrated that caffeine is a potential teratogen. It causes asymmetrical microphthalmia to develop by increasing ROS production and perturbs Pax6 expression. PMID:24636305

  9. Embryonal rhabdomyosarcoma of the cervix

    Directory of Open Access Journals (Sweden)

    Ocheke A

    2011-01-01

    Full Text Available Embryonal rhabdomyosarcoma (sarcoma botyroides of the cervix, which is rare, is described in a 16-year-old. The combined use of chemotherapy, radiotherapy and surgery has markedly improved survival in those with this condition. However, our patient did not benefit from this treatment modality due to late presentation and loss to follow-up.

  10. Pulsating instability and self-acceleration of fast turbulent flames

    CERN Document Server

    Poludnenko, A Y

    2015-01-01

    (Abridged) A series of three-dimensional numerical simulations is used to study the intrinsic stability of high-speed turbulent flames. Calculations model the interaction of a fully-resolved premixed flame with a highly subsonic, statistically steady, homogeneous, isotropic turbulence. We consider a wide range of turbulent intensities and system sizes, corresponding to the Damk\\"ohler numbers Da = 0.1-6.0. These calculations show that turbulent flames in the regimes considered are intrinsically unstable. In particular, we find three effects. 1) Turbulent flame speed develops pulsations with the observed peak-to-peak amplitude > 10 and a characteristic time scale close to a large-scale eddy turnover time. Such variability is caused by the interplay between turbulence, which continuously creates the flame surface, and highly intermittent flame collisions, which consume the flame surface. 2) Unstable burning results in the periodic pressure build-up and the formation of pressure waves or shocks, when the flame s...

  11. Dynamic response of nuclear fuel assembly excited by pressure pulsations

    Directory of Open Access Journals (Sweden)

    Zeman V.

    2012-12-01

    Full Text Available The paper deals with dynamic load calculation of the hexagonal type nuclear fuel assembly caused by spatial motion of the support plates in the reactor core. The support plate motion is excited by pressure pulsations generated by main circulation pumps in the coolant loops of the primary circuit of the nuclear power plant. Slightly different pumps revolutions generate the beat vibrations which causes an amplification of fuel assembly component dynamic deformations and fuel rods coating abrasion. The cyclic and central symmetry of the fuel assembly makes it possible the system decomposition into six identical revolved fuel rod segments which are linked with central tube and skeleton by several spacer grids in horizontal planes.The modal synthesis method with condensation of the fuel rod segments is used for calculation of the normal and friction forces transmitted between fuel rods and spacer grids cells.

  12. Zinc electrodeposition from alkaline zincate solution by pulsating overpotentials

    Directory of Open Access Journals (Sweden)

    MILOS V. SIMICIC

    2000-09-01

    Full Text Available It is well known that smooth zinc deposits cannot be obtained from alkaline zincate using constant overpotential and current rate. During prolonged metal deposition, spongy and dendritic deposits are formed. It has been shown that the deposits are less agglomerated in the case of square-wave pulsating overpotentials regime than the ones obtained in case of constant overpotential regime. This is explained in a semiquantitative way by two phenomena: selective anodic dissolution during overpotentials “off” period and decreasing diffusion control. These effects is more pronounced at higher pause-to-pulse ratio. Increasing the pause-to-pulse ratio causes a reduction of the ratio between diffusion and activation overpotential, resulting in a more compact deposit. Confirmation of the proposed semiquantitative mathematical model was obtained by zinc electrodeposition onto a copper wire from a 0.1 M zincate solution in 1.0 M KOH at room temperature.

  13. Asteroseismology of pulsating DA white dwarfs with fully evolutionary models

    Directory of Open Access Journals (Sweden)

    Althaus L.G.

    2013-03-01

    Full Text Available We present a new approach for asteroseismology of DA white dwarfs that consists in the employment of a large set of non-static, physically sound, fully evolutionary models representative of these stars. We already have applied this approach with success to pulsating PG1159 stars (GW Vir variables. Our white dwarf models, which cover a wide range of stellar masses, effective temperatures, and envelope thicknesses, are the result of fully evolutionary computations that take into account the complete history of the progenitor stars from the ZAMS. In particular, the models are characterized by self-consistent chemical structures from the centre to the surface, a crucial aspect of white dwarf asteroseismology. We apply this approach to an ensemble of 44 bright DAV (ZZ Ceti stars.

  14. Mathematical Modelling and Parameter Optimization of Pulsating Heat Pipes

    CERN Document Server

    Yang, Xin-She; Luan, Tao; Koziel, Slawomir

    2014-01-01

    Proper heat transfer management is important to key electronic components in microelectronic applications. Pulsating heat pipes (PHP) can be an efficient solution to such heat transfer problems. However, mathematical modelling of a PHP system is still very challenging, due to the complexity and multiphysics nature of the system. In this work, we present a simplified, two-phase heat transfer model, and our analysis shows that it can make good predictions about startup characteristics. Furthermore, by considering parameter estimation as a nonlinear constrained optimization problem, we have used the firefly algorithm to find parameter estimates efficiently. We have also demonstrated that it is possible to obtain good estimates of key parameters using very limited experimental data.

  15. Making a Be star: the role of rotation and pulsations

    CERN Document Server

    Neiner, C

    2013-01-01

    The Be phenomenon, i.e. the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT satellite brought clear evidence that Be outbursts are directly correlated to pulsations and rapid rotation. In particular the stochastic excitation of gravito-inertial modes, such as those detected by CoRoT in the hot Be star HD 51452, is enhanced thanks to rapid rotation. These waves increase the transport of angular momentum and help to bring the already rapid stellar rotation to its critical value at the surface, allowing the star to eject material. Below we summarize the recent observational and theoretical findings and describe the new picture of the Be phenomenon which arose from these results.

  16. Making a Be star: the role of rotation and pulsations

    Science.gov (United States)

    Neiner, Coralie; Mathis, Stéphane

    2014-02-01

    The Be phenomenon, i.e. the ejection of matter from Be stars into a circumstellar disk, has been a long lasting mystery. In the last few years, the CoRoT satellite brought clear evidence that Be outbursts are directly correlated to pulsations and rapid rotation. In particular the stochastic excitation of gravito-inertial modes, such as those detected by CoRoT in the hot Be star HD 51452, is enhanced thanks to rapid rotation. These waves increase the transport of angular momentum and help to bring the already rapid stellar rotation to its critical value at the surface, allowing the star to eject material. Below we summarize the recent observational and theoretical findings and describe the new picture of the Be phenomenon which arose from these results.

  17. Pulsating jet-like structures in magnetized plasma

    Science.gov (United States)

    Goncharov, V. P.; Pavlov, V. I.

    2016-08-01

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as "radio pulsars." The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  18. Non-radial Pulsations in the Open Cluster NGC 3766

    CERN Document Server

    Roettenbacher, Rachael M; McSwain, M Virginia

    2009-01-01

    Non-radial pulsations (NRPs) are a proposed mechanism for the formation of decretion disks around Be stars and are important tools to study the internal structure of stars. NGC 3766 has an unusually large fraction of transient Be stars, so it is an excellent location to study the formation mechanism of Be star disks. High resolution spectroscopy can reveal line profile variations from NRPs, allowing measurements of both the degree, l, and azimuthal order, m. However, spectroscopic studies require large amounts of time with large telescopes to achieve the necessary high S/N and time domain coverage. On the other hand, multi-color photometry can be performed more easily with small telescopes to measure l only. Here, we present representative light curves of Be stars and non-emitting B stars in NGC 3766 from the CTIO 0.9m telescope in an effort to study NRPs in this cluster.

  19. A 'one in a million' case of pulsating thoracoabdominal mass.

    LENUS (Irish Health Repository)

    Tan, Lay Ong

    2012-11-01

    Ectopia cordis is a rare congenital malformation in which the heart is located partially or totally outside the thoracic cavity. It comprises 0.1% of congenital heart diseases. The authors present a case of a male baby born at term by emergency caesarean section due to prolonged fetal bradycardia, who was noted to have a large pulsating mass in the thoracoabdominal area. In view of lower thoracolumbar abdominal defect, ectopic placement of the umbilicus, deficiency of the diaphragmatic pericardium, deficiency of anterior diaphragm and intracardiac abnormalities, a diagnosis of ectopia cordis-Pentalogy of Cantrell was made. He was transferred to a tertiary centre and required oxygen supplement initially. He was sent home after 1 week, on propanolol, with weekly oxygen saturation checks. He is awaiting further surgical intervention pending the required weight gain.

  20. An application of Bayesian inference for solar-like pulsators

    Science.gov (United States)

    Benomar, O.

    2008-12-01

    As the amount of data collected by space-borne asteroseismic instruments (such as CoRoT and Kepler) increases drastically, it will be useful to have automated processes to extract a maximum of information from these data. The use of a Bayesian approach could be very help- ful for this goal. Only a few attempts have been made in this way (e.g. Brewer et al. 2007). We propose to use Markov Chain Monte Carlo simulations (MCMC) with Metropolis-Hasting (MH) based algorithms to infer the main stellar oscillation parameters from the power spec- trum, in the case of solar-like pulsators. Given a number of modes to be fitted, the algorithm is able to give the best set of parameters (frequency, linewidth, amplitude, rotational split- ting) corresponding to a chosen input model. We illustrate this algorithm with one of the first CoRoT targets: HD 49933.

  1. Cerebrospinal fluid flow. Pt. 3; Pathological cerebrospinal fluid pulsations

    Energy Technology Data Exchange (ETDEWEB)

    Schroth, G. (Dept. of Neuradiology, Tuebingen Univ. (Germany)); Klose, U. (Dept. of Neuradiology, Tuebingen Univ. (Germany))

    1992-12-01

    Cardiac- and respiration-related movements of the cerebrospinal fluid (CSF) were investigated by MRI in 71 patients. In most patients with arteriosclerotic occlusive vascular disease CSF pulsations are normal. Decreased pulsatile flow is detectable in those with arteriovenous malformations, intracranial air and following lumbar puncture and withdrawal of CSF. Increased pulsatile flow in the cerebral aqueduct was found in 2 patients with large aneurysms, idiopathic communicating syringomyelia and in most cases of normal pressure hydrocephalus (NPH). CSF flow in the cervical spinal canal is, however, reduced or normal in NPH, indicating reduction of the unfolding ability of the surface of the brain and/or inhibition of rapid CSF movements in the subrachnoid space over its convexity. (orig.)

  2. Kidney alkaline phosphatase in mercuric chloride injected chicks resistant and susceptible to leukosis

    Energy Technology Data Exchange (ETDEWEB)

    Miller, V.L.; McIntyre, J.A.; Bearse, G.E.

    1969-01-01

    Two strains of chickens were selected for resistance and susceptibility to avian leukosis. Researchers found that the resistant chicks retained two to four times as much mercury in the liver and kidneys as did the susceptible chicks following injection of mercuric chloride or phenylmercuric acetate. Differences in alkaline phosphatase in the kidneys of the resistant and susceptible chicks, and the effect of the mercuric chloride injection on the alkaline phosphatase activity were reported in this paper. 19 references, 2 tables.

  3. Early embryonic intra-cardiac flow fields at three idealized ventricular morphologies

    Science.gov (United States)

    Pekkan, Kerem; Jamaly, Mohammad; Kara, Burak; Keller, Bradley; Sotiropoulos, Fotis

    2009-11-01

    Pulsatile 3D multiple inlet/outlet flow within tiny (100-300μm dia) embryonic ventricles feature distinct intra-cardiac flow streams whose role in regulating the morphogenesis of spiral aorto-pulmonary septum has long been debated. The low Re number flow regimes limit mixing of these streams as replicated in our flow-visualization experiments with chick embryos. A state-of-the art high-resolution immersed boundary CFD solver which was developed for complex patient-specific cardiovascular internal flow problems is applied and optimized for this problem. Idealized tubular ventricles at 3 major embryonic stages (straight, C- and D- loops) are created by our sketch-based anatomical editing tool. CFD results are validated with PIV measurements acquired from a micro-fabricated C-loop stage replica and in vivo flow vis data from confocal microscopy. This model provided the inlet velocity profile for arterial models and flow fields at the inner curvature of embryonic hearts for different ventricular topologies are compared for off-design modes.

  4. Dependences between kinetics of the human eye pupil and blood pulsation

    Science.gov (United States)

    Szmigiel, Marta A.; Kasprzak, Henryk; Klysik, Anna

    2016-09-01

    The study presents measurement and numerical analysis of time variability of the eye pupil geometry and its position, as well as their correlations with blood pulsation. The image of the eye pupil was recorded by use of the fast CCD camera with 200 fps rates. Blood pulsation was synchronously recorded by use of pulse transducer with the sampling frequency of 200 Hz. Each single image from a sequence was numerically processed. Contour of the eye pupil was approximated, and its selected geometrical parameters as well as center positions were calculated. Spectral and coherence analysis of time variability of calculated pupil parameters and blood pulsation were determined.

  5. A Novel Pre-cooling System for a Cryogenic Pulsating Heat Pipe

    Science.gov (United States)

    Xu, Dong; Liu, Huiming; Gong, Linghui; Xu, Xiangdong; Li, Laifeng

    To reduce the influence of the pipe material on the measurement of effective thermal conductivity, the pipe of a cryogenic pulsating heat pipe is generally made of stainless steel. Because of the low thermal conductivity of stainless steel, the pre-cooling of the evaporator in cryogenic pulsating heat pipe using helium as working fluid at 4.2 K is a problem. We designed a mechanical-thermal switch between the cryocooler and the evaporator, which was on during the pre-cooling process and off during the test process. By using the pre-cooling system, the cool down time of the cryogenic pulsating heat pipe was reduced significantly.

  6. Relationship of spontaneous retinal vein pulsation with ocular circulatory cycle.

    Directory of Open Access Journals (Sweden)

    Mijin Kim

    Full Text Available PURPOSE: To determine the timing of spontaneous venous pulsation (SVP relative to the ocular circulatory cycle by using the movie tool of confocal scanning laser ophthalmoloscope. METHODS: A video recording of the fundus was obtained using a confocal scanning laser ophthalmoscope (Spectralis HRA, Heidelberg Engineering, Heidelberg, Germany at 8 frames/s in 47 eyes (15 glaucoma patients and 32 glaucoma suspects with visible pulsation of both the central retinal artery (CRA and vein (CRV. The timing of the maximum and minimum diameters of the CRA (CRA(max and CRAmin, respectively and CRV (CRV(max and CRV(min, respectively was identified during four pulse cycles. The interval between CRV(min and CRA(min, and between CRV(max and CRA(max was expressed as the number of frames and as a percentage of the ocular circulatory cycle. RESULTS: The ocular circulatory cycle (from one CRA(max to the next lasted 7.7 ± 1.0 frames (958.8 ± 127.2 ms, mean ± SD, with a mean pulse rate of 62.6 beats/min. The diameter of the CRA was increased for 2.4 ± 0.5 frames (301.9 ± 58.8 ms and decreased for 5.3 ± 0.9 frames (656.9 ± 113.5 ms. CRV(max occurred 1.0 ± 0.2 frames after CRA(max (equivalent to 13.0% of the ocular circulatory cycle, while CRV(min occurred 1.1 ± 0.4 frames after CRA(min (equivalent to 14.6% of the ocular circulatory cycle. CONCLUSIONS: During SVP, the diameter of the CRV began to decrease at early diastole, and the reduction persisted until early systole. This finding supports that CRV collapse occurs during ocular diastole.

  7. Pulsation, Mass Loss and the Upper Mass Limit

    Science.gov (United States)

    Klapp, J.; Corona-Galindo, M. G.

    1990-11-01

    RESUMEN. La existencia de estrellas con masas en exceso de 100 M0 ha sido cuestionada por mucho tiempo. Lfmites superiores para la masa de 100 M0 han sido obtenidos de teorfas de pulsaci6n y formaci6n estelar. En este trabajo nosotros primero investigamos la estabilidad radial de estrellas masivas utilizando la aproximaci6n clasica cuasiadiabatica de Ledoux, la aproximaci6n cuasiadiabatica de Castor y un calculo completamente no-adiabatico. Hemos encontrado que los tres metodos de calculo dan resultados similares siempre y cuando una pequefia regi6n de las capas externas de la estrella sea despreciada para la aproximaci6n clasica. La masa crftica para estabilidad de estrellas masivas ha sido encontrada en acuerdo a trabajos anteriores. Explicamos Ia discrepancia entre este y trabajos anteriores por uno de los autores. Discunmos calculos no-lineales y perdida de masa con respecto a) lfmite superior de masa. The existence of stars with masses in excess of 100 M0 has been questioned for a very long time. Upper mass limits of 100 Me have been obtained from pulsation and star formation theories. In this work we first investigate the radial stability of massive stars using the classical Ledoux's quasiadiabatic approximation. the Castor quasiadiabatic approximation and a fully nonadiabatic calculation. We have found that the three methods of calculation give similar results provided that a small region in outer layers of the star be neglected for the classical approximation. The critical mass for stability of massive stars is found to be in agreement with previous work. We explain the reason for the discrepancy between this and previous work by one of the authors. We discuss non-linear calculations and mass loss with regard to the upper mass limit. Key words: STARS-MASS FUNCTION - STARS-MASS LOSS - STARS-PULSATION

  8. Correlation between plasma steroids and chick visits by nonbreeding adult Nazca boobies.

    Science.gov (United States)

    Tarlow, Elisa M; Wikelski, Martin; Anderson, David J

    2003-03-01

    Nonbreeding adult Nazca boobies (Sula granti) often approach unattended chicks and perform parental and/or aggressive behaviors toward the chicks. Earlier descriptions of these encounters included sexual behaviors as well. We studied hormonal correlates of chick visits by such nonbreeding boobies during the breeding season. We compared the hormonal status of chick-visiting adults with that of nonvisiting adults in the colony. We determined levels of corticosterone (CORT), testosterone (T), androstendione, dihydrotestosterone, and estradiol as potential candidate hormones controlling parental, aggressive, or sexual behavior. Only T and CORT differed between chick-visiting and nonvisiting adults. Chick-visiting adults had higher CORT levels after the interaction than nonvisiting adults randomly caught in the colony. To the contrary. T levels after interactions were lower in chick-visiting compared to random nonvisiting adults. T levels, however, did not vary with level of aggression among chick-visiting adults. We suggest that chick-visiting behavior may be permitted by low T levels and activated by, or resulting in, high CORT levels.

  9. Indirect cannibalism by crèche-aged American White Pelican (Pelecanus erythrorhynchos) chicks

    Science.gov (United States)

    Bartos, Alisa J.; Sovada, Marsha A.; Igl, Lawrence D.; Pietz, Pamela J.

    2013-01-01

    At nesting colonies of American White Pelicans (Pelecanus erythrorhynchos), many chicks die from siblicide, severe weather, and disease; this results in carcasses available for scavenging by conspecifics (i.e., indirect cannibalism). Indirect cannibalism has not been reported previously for this species. We describe five cases of crèche-aged American White Pelican chicks consuming or attempting to consume dead younger chicks at two nesting colonies in the northern plains of North America. Cannibalism in the American White Pelican appears to be rare and likely plays no role in the species’ population ecology or dynamics; however, it might be an important survival strategy of individual chicks when food resources are limited.

  10. Dietary chromium methionine supplementation could alleviate immunosuppressive effects of heat stress in broiler chicks.

    Science.gov (United States)

    Jahanian, R; Rasouli, E

    2015-07-01

    The present study was conducted to investigate the effects of dietary supplementation of chromium methionine (CrMet) on performance, immune responses, and stress status of broiler chicks subjected to heat-stress conditions. A total of 450 day-old Ross 308 broiler chicks were randomly distributed between 5 replicate pens (15 birds each) of 6 experimental treatments according to a 2 × 3 factorial arrangement of treatments including 2 temperature conditions (thermoneutral and heat stress) and 3 supplemental Cr levels (0, 500, and 1,000 μg/kg as CrMet). For induction of heat stress, the house temperature was set at 35 ± 2°C from 15 to 42 d of age. Results showed that the chicks subjected to heat-stress condition had lower (P heat-stressed chicks. Exposure to heat stress suppressed (P heat-stressed chicks, resulting in a significant (P heat-stressed chicks. Dietary inclusion of CrMet improved (P heat-stressed chicks. Exposure to heat stress caused a significant (P heat-stressed chicks modulated (P heat-stress-induced growth retardation in broiler chicks. Moreover, supplemental CrMet modulated suppressive effects of heat stress on cellular and humoral immune responses.

  11. The effects of ingested plastic on growth and survival of albatross chicks

    Science.gov (United States)

    Sievert, Paul R.; Sileo, Louis

    1993-01-01

    We studied the effects of ingested plastic on the growth and survival of chicks of Laysan Albatrosses Diomedea immutabilis and Black-footed albatrosses D. nigripes on Midway Atoll during the nesting seasons of 1986 and 1987. Weights and proventricular contents of the chicks were determined periodically through the nesting cycle. Large (>22 cm1)volumes of plastic were present in the proventriculi of 27% of the Laysan and 16% of the Black-footed albatross chicks examined by endoscopy. Prior to fledging, albatross chicks regurgitated pellets composed of plastic and other indigestible material from their proventriculi. Laysan Albatross chicks with large volumes of proventricular plastic had asymptotic fledging weights significantly lower (122 g) than did chicks with low amounts of plastic. The effect of depresses fledging weights on postfledging survival was not determined. Plastic had no detectable effect on the growth of Black-footed Albatross chicks. All chicks that died were examined by necropsy. Mechanical lesions from ingested plastic were the cause of death of one of 45 Laysan Albatross chicks examined in 1986, but were not the cause of death of 93 individuals examined in 1987. Dehydration was the most common cause of death. In general, ingested plastic was not a significant direct cause of death in nestlings, but there was some evidence that it may have affected survival in 1986, when the volume of plastic ingested was highest.

  12. A study on the growth curve of and maximum profit from layer-type cockerel chicks.

    Science.gov (United States)

    Gang, F Y; Zhen, Y S

    1997-09-01

    1. 2900 commercial layer-type cockerel chicks were reared on the floor from 1-day-old to 9 weeks of age. 2. The growth curve of the cockerel chicks was [formula see text] 3. The feeding costs (US$) of layer-type cockerel chicks were described by the equation Y = a + bx + cx2 = 0.0657 - 0.0091x + 0.0069x2. 4. When the layer-type cockerel chicks' marketing price was US$0.82 per kg. (6.8 Renminbi per kg), the optimum marketing age for maximum profit margin was 5.9 weeks (41 to 42 d).

  13. Chick ex ovo culture and ex ovo CAM assay: how it really works

    National Research Council Canada - National Science Library

    Dohle, Daniel S; Pasa, Susanne D; Gustmann, Sebastian; Laub, Markus; Wissler, Josef H; Jennissen, Herbert P; Dünker, Nicole

    2009-01-01

    .... After the chick chorioallantoic membrane (CAM) has developed, its blood vessel network can be easily accessed, manipulated and observed and therefore provides an optimal setting for angiogenesis assays...

  14. Effects of breeder age and egg weight on morphological changes in the small intestine of chicks during the hatch window.

    Science.gov (United States)

    Yalçin, S; Izzetoğlu, G T; Aktaş, A

    2013-01-01

    1. The objective of the study was to investigate the effects of breeder age and egg weight on hatching performance and morphological changes in segments of the small intestine of broiler chicks during a 21 h hatch window. 2. Eggs from Ross broiler breeder flocks aged 29 (young) and 48 weeks (old) were classified as light (LE) or heavy (HE) and incubated at the same conditions. At 475 h of incubation, eggs were checked every 3 h to determine time of external pipping and hatching. The first 42 chicks to emerge from each group were weighed and chick length was measured and 14 chicks from each group were sampled to collect residual yolk and intestine segments. The rest of chicks were placed back in the incubator and chick weight and length were measured individually at 9, 15 and 21 h after chicks hatched. At the end of 21 h, 14 chicks from each group were sampled again and the same procedure was followed. 3. The HE chicks pipped and hatched later than LE, regardless of breeder age. From hatch to the end of the hatch window, chick weight, but not yolk-free chick weight, gradually reduced. Relative residual yolk weight of chicks from both egg weights was similar at hatch, however, yolk sac utilisation was higher for LE chicks during the 21 h post-hatch period. At hatch, jejunum and ileum villus development was very similar for HE and LE chicks but greater development was observed for villus area with an increase in the jejunum villus length, width and goblet cell numbers in HE chicks. 4. The longest jejunum villus and the widest duodenum and jejunum villus were obtained for HE chicks from old breeders indicating that HE chicks from old breeders would have a greater surface area for nutrient absorption.

  15. Muscarinic signaling influences the patterning and phenotype of cholinergic amacrine cells in the developing chick retina

    Directory of Open Access Journals (Sweden)

    Fischer Andy J

    2008-02-01

    Full Text Available Abstract Background Many studies in the vertebrate retina have characterized the differentiation of amacrine cells as a homogenous class of neurons, but little is known about the genes and factors that regulate the development of distinct types of amacrine cells. Accordingly, the purpose of this study was to characterize the development of the cholinergic amacrine cells and identify factors that influence their development. Cholinergic amacrine cells in the embryonic chick retina were identified by using antibodies to choline acetyltransferase (ChAT. Results We found that as ChAT-immunoreactive cells differentiate they expressed the homeodomain transcription factors Pax6 and Islet1, and the cell-cycle inhibitor p27kip1. As differentiation proceeds, type-II cholinergic cells, displaced to the ganglion cell layer, transiently expressed high levels of cellular retinoic acid binding protein (CRABP and neurofilament, while type-I cells in the inner nuclear layer did not. Although there is a 1:1 ratio of type-I to type-II cells in vivo, in dissociated cell cultures the type-I cells (ChAT-positive and CRABP-negative out-numbered the type-II cells (ChAT and CRABP-positive cells by 2:1. The relative abundance of type-I to type-II cells was not influenced by Sonic Hedgehog (Shh, but was affected by compounds that act at muscarinic acetylcholine receptors. In addition, the abundance and mosaic patterning of type-II cholinergic amacrine cells is disrupted by interfering with muscarinic signaling. Conclusion We conclude that: (1 during development type-I and type-II cholinergic amacrine cells are not homotypic, (2 the phenotypic differences between these subtypes of cells is controlled by the local microenvironment, and (3 appropriate levels of muscarinic signaling between the cholinergic amacrine cells are required for proper mosaic patterning.

  16. Clonal distribution of osteoprogenitor cells in cultured chick periostea: Functional relationship to bone formation

    Energy Technology Data Exchange (ETDEWEB)

    McCulloch, C.A.; Fair, C.A.; Tenenbaum, H.C.; Limeback, H.; Homareau, R. (Univ. of Toronto, Ontario (Canada))

    1990-08-01

    Folded explants of periosteum from embryonic chick calvaria form bone-like tissue when grown in the presence of ascorbic acid, organic phosphate, and dexamethasone. All osteoblast-like cells in these cultures arise de novo by differentiation of osteoprogenitor cells present in the periosteum. To study the spatial and functional relationships between bone formation and osteoprogenitor cells, cultures were continuously labeled with (3H)thymidine for periods of 1-5 days. Radioautographs of serial 2-microns plastic sections stained for alkaline phosphatase (AP) showed maximal labeling of 30% of fibroblastic (AP-negative) cells by 3 days while osteogenic cells (AP-positive) exhibited over 95% labeling by 5 days. No differential shifts in labeling indices, grain count histograms of fibroblastic and osteogenic cells or numbers of AP-positive cells were observed, indicating no significant recruitment of cells from the fibroblastic to the osteogenic compartment. Despite the continuous presence of (3H)thymidine, less than 35% of both osteoblasts and osteocytes were labeled at 5 days, indicating that only one-third of the osteoprogenitor cells had cycled prior to differentiation. Spatial clustering of (3H)thymidine-labeled cells was measured by computer-assisted morphometry and application of the Poisson distribution to assess contagion. Cluster size and number of labeled cells per cluster did not vary between 1-3 days, but the number of clusters increased 20-fold between Day 1 and Day 3. Three-dimensional reconstruction from serial sections showed that clusters formed long, tubular arrays of osteogenic cells up to eight cells in length and located within 2-3 cell layers from the bone surface. Selective killing of S-phase cells with two pulse labels of high specific activity (3H)thymidine at 1 and 2 days of culture completely blocked bone formation.

  17. Influence of melatonin on the development of functional nicotinic acetylcholine receptors in cultured chick retinal cells

    Directory of Open Access Journals (Sweden)

    L.F.S. Sampaio

    2005-04-01

    Full Text Available The influence of melatonin on the developmental pattern of functional nicotinic acetylcholine receptors was investigated in embryonic 8-day-old chick retinal cells in culture. The functional response to acetylcholine was measured in cultured retina cells by microphysiometry. The maximal functional response to acetylcholine increased 2.7 times between the 4th and 5th day in vitro (DIV4, DIV5, while the Bmax value for [125I]-alpha-bungarotoxin was reduced. Despite the presence of alpha8-like immunoreactivity at DIV4, functional responses mediated by alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors were observed only at DIV5. Mecamylamine (100 µM was essentially without effect at DIV4 and DIV5, while dihydro-ß-erythroidine (10-100 µM blocked the response to acetylcholine (3.0 nM-2.0 µM only at DIV4, with no effect at DIV5. Inhibition of melatonin receptors with the antagonist luzindole, or melatonin synthesis by stimulation of D4 dopamine receptors blocked the appearance of the alpha-bungarotoxin-sensitive response at DIV5. Therefore, alpha-bungarotoxin-sensitive receptors were expressed in retinal cells as early as at DIV4, but they reacted to acetylcholine only after DIV5. The development of an alpha-bungarotoxin-sensitive response is dependent on the production of melatonin by the retinal culture. Melatonin, which is produced in a tonic manner by this culture, and is a key hormone in the temporal organization of vertebrates, also potentiates responses mediated by alpha-bungarotoxin-sensitive receptors in rat vas deferens and cerebellum. This common pattern of action on different cell models that express alpha-bungarotoxin-sensitive receptors probably reflects a more general mechanism of regulation of these receptors.

  18. Radial velocity measurements of the pulsating zirconium star: LS IV -14 116

    CERN Document Server

    Jeffery, C Simon; Neelamkodan, Naslim; Kerzendorf, Wolfgang

    2014-01-01

    The helium-rich hot subdwarf LS IV -14 116 shows remarkably high surface abundances of zirconium, yttrium, strontium, and germanium, indicative of strong chemical stratification in the photosphere. It also shows photometric behaviour indicative of non-radial g-mode pulsations, despite having surface properties inconsistent with any known pulsational instability zone. We have conducted a search for radial velocity variability. This has demonstrated that at least one photometric period is observable in several absorption lines as a radial velocity variation with a semi-amplitude in excess of 5 km s$^{-1}$. A correlation between line strength and pulsation amplitude provides evidence that the photosphere pulsates differentially. The ratio of light to velocity amplitude is too small to permit the largest amplitude oscillation to be radial.

  19. Quantitative assessment of the impact of blood pulsation on images of the pupil in infrared light.

    Science.gov (United States)

    Koprowski, Robert; Szmigiel, Marta; Kasprzak, Henryk; Wróbel, Zygmunt; Wilczyński, Sławomir

    2015-08-01

    Pulsation in the blood vessels of the eye has a big impact on the dynamics of the entire eyeball and its individual elements. Blood pulsation in the retina can be recorded by the pupil, whose size is also subject to dynamic changes. The study involved synchronous measurements of pupil size using a high-speed camera, and blood pulsation using a pulse oximeter placed on the ear lobe. In addition, there were no metrologically significant differences in the phase shift between the average brightness of the individual pupil quadrants. Blood pulsation in other ocular tissues can affect the dynamics of the optical properties of the eye. As demonstrated in this paper, it affects the pupil behavior and its parameters to a considerable extent.

  20. Impact of Pulsation Activity on the Light Curves of Symbiotic Variables

    CERN Document Server

    Marsakova, Vladyslava I; Chinarova, Lidia L; Chyzhyk, Maksim S; Andrych, Kateryna D

    2015-01-01

    We used long-term visual amateur observations of several symbiotic variables for detection of periods that may be caused by pulsation. The examples of multiple periodicities are discussed individually in each case.

  1. Recent advances in the theoretical modeling of pulsating low-mass He-core white dwarfs

    CERN Document Server

    Córsico, A H; Calcaferro, L M; Serenelli, A M; Kepler, S O; Jeffery, C S

    2016-01-01

    Many extremely low-mass (ELM) white-dwarf (WD) stars are currently being found in the field of the Milky Way. Some of these stars exhibit long-period nonradial $g$-mode pulsations, and constitute the class of ELMV pulsating WDs. In addition, several low-mass pre-WDs, which could be precursors of ELM WDs, have been observed to show short-period photometric variations likely due to nonradial $p$ modes and radial modes. They could constitute a new class of pulsating low-mass pre-WD stars, the pre-ELMV stars. Here, we present the recent results of a thorough theoretical study of the nonadiabatic pulsation properties of low-mass He-core WDs and pre-WDs on the basis of fully evolutionary models representative of these stars.

  2. A Novel Multisection Distributed Feedback Laser with Varied Ridge Width for Self-Pulsation Generation

    Institute of Scientific and Technical Information of China (English)

    WAN Qin; SUN Chang-Zheng; XIONG Bing; WANG Jian; LUO Yi

    2006-01-01

    @@ A novel ridge-waveguide multisection (MS) distributed feedback (DFB) laser, which consists of two identical DFB sections but different ridge widths, is proposed to generate beating-type self-pulsations (SPs).

  3. NUMERICAL SIMULATION AND ANALYSIS OF PRESSURE PULSATION IN FRANCIS HYDRAULIC TURBINE WITH AIR ADMISSION

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, the three-dimensional unsteady multiphase flow is simulated in the whole passage of Francis hydraulic turbine. The pressure pulsation is predicted and compared with experimental data at positions in the draft tube, in front of runner, guide vanes and at the inlet of the spiral case. The relationship between pressure pulsation in the whole passage and air admission is analyzed. The computational results show: air admission from spindle hole decreases the pressure difference in the horizontal section of draft tube, which in turn decreases the amplitude of low-frequency pressure pulsation in the draft tube; the rotor-stator interaction between the air inlet and the runner increases the blade-frequency pressure pulsation in front of the runner.

  4. Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha

    CERN Document Server

    Böhm, T; Catala, C; Alecian, E; Pollard, K; Wright, D

    2008-01-01

    In this article we present a first discovery of non radial pulsations in both components of the Herbig Ae spectroscopic binary star RS Cha. The binary was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with $R = 45000$. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. In fact, both components of the spect...

  5. New Pulsating DB White Dwarf Stars from the Sloan Digital Sky Survey

    CERN Document Server

    Nitta, A; Krzesínski, J; Kepler, S O; Metcalfe, T S; Mukadam, Anjum S; Mullally, Fergal; Nather, R E; Sullivan, Denis J; Thompson, Susan E; Winget, D E

    2008-01-01

    We are searching for new He atmosphere white dwarf pulsators (DBVs) based on the newly found white dwarf stars from the spectra obtained by the Sloan Digital Sky Survey. DBVs pulsate at hotter temperature ranges than their better known cousins, the H atmosphere white dwarf pulsators (DAVs or ZZ Ceti stars). Since the evolution of white dwarf stars is characterized by cooling, asteroseismological studies of DBVs give us opportunities to study white dwarf structure at a different evolutionary stage than the DAVs. The hottest DBVs are thought to have neutrino luminosities exceeding their photon luminosities (Winget et al. 2004), a quantity measurable through asteroseismology. Therefore, they can also be used to study neutrino physics in the stellar interior. So far we have discovered nine new DBVs, doubling the number of previously known DBVs. Here we report the new pulsators' lightcurves and power spectra.

  6. Spatio-temporal Dynamics of Sources of Hard X-Ray Pulsations in Solar Flares

    Science.gov (United States)

    Kuznetsov, S. A.; Zimovets, I. V.; Morgachev, A. S.; Struminsky, A. B.

    2016-11-01

    We present a systematic analysis of the spatio-temporal evolution of sources of hard X-ray (HXR) pulsations in solar flares. We concentrate on disk flares whose impulsive phases are accompanied by a series of more than three successive peaks (pulsations) of HXR emission detected in the RHESSI 50 - 100 keV energy channel with a four-second time cadence. Twenty-nine such flares observed from February 2002 to June 2015 with characteristic time differences between successive peaks P ≈8 - 270 s are studied. The main observational result of the analysis is that sources of HXR pulsations in all flares are not stationary, they demonstrate apparent movements or displacements in the parent active regions from pulsation to pulsation. The flares can be subdivided into two main groups depending on the character of the dynamics of the HXR sources. Group 1 consists of 16 flares (55 %) that show systematic dynamics of the HXR sources from pulsation to pulsation with respect to a magnetic polarity inversion line (MPIL), which has a simple extended trace on the photosphere. Group 2 consists of 13 flares (45 %) that show more chaotic displacements of the HXR sources with respect to an MPIL with a more complex structure, and sometimes several MPILs are present in the parent active regions of such flares. Based on the observations, we conclude that the mechanism of the flare HXR pulsations (at least with time differences of the considered range) is related to successive triggering of the flare energy release process in different magnetic loops (or bundles of loops) of the parent active regions. Group 1 flare regions consist of loops stacked into magnetic arcades that are extended along MPILs. Group 2 flare regions have more complex magnetic structures, and the loops are arranged more chaotically and randomly there. We also found that at least 14 (88 %) group 1 flares and 11 (85 %) group 2 flares are accompanied by coronal mass ejections (CMEs), i.e. the absolute majority of the

  7. Spatio-temporal Dynamics of Sources of Hard X-Ray Pulsations in Solar Flares

    Science.gov (United States)

    Kuznetsov, S. A.; Zimovets, I. V.; Morgachev, A. S.; Struminsky, A. B.

    2016-09-01

    We present a systematic analysis of the spatio-temporal evolution of sources of hard X-ray (HXR) pulsations in solar flares. We concentrate on disk flares whose impulsive phases are accompanied by a series of more than three successive peaks (pulsations) of HXR emission detected in the RHESSI 50 - 100 keV energy channel with a four-second time cadence. Twenty-nine such flares observed from February 2002 to June 2015 with characteristic time differences between successive peaks P ≈8 - 270 s are studied. The main observational result of the analysis is that sources of HXR pulsations in all flares are not stationary, they demonstrate apparent movements or displacements in the parent active regions from pulsation to pulsation. The flares can be subdivided into two main groups depending on the character of the dynamics of the HXR sources. Group 1 consists of 16 flares ( 55~%) that show systematic dynamics of the HXR sources from pulsation to pulsation with respect to a magnetic polarity inversion line (MPIL), which has a simple extended trace on the photosphere. Group 2 consists of 13 flares ( 45~%) that show more chaotic displacements of the HXR sources with respect to an MPIL with a more complex structure, and sometimes several MPILs are present in the parent active regions of such flares. Based on the observations, we conclude that the mechanism of the flare HXR pulsations (at least with time differences of the considered range) is related to successive triggering of the flare energy release process in different magnetic loops (or bundles of loops) of the parent active regions. Group 1 flare regions consist of loops stacked into magnetic arcades that are extended along MPILs. Group 2 flare regions have more complex magnetic structures, and the loops are arranged more chaotically and randomly there. We also found that at least 14 ( 88~%) group 1 flares and 11 ( 85~%) group 2 flares are accompanied by coronal mass ejections (CMEs), i.e. the absolute majority of the

  8. Changes in free amino acid and monoamine concentrations in the chick brain associated with feeding behavior.

    Science.gov (United States)

    Tran, Phuong V; Chowdhury, Vishwajit S; Nagasawa, Mao; Furuse, Mitsuhiro

    2015-01-01

    Domesticated chicks are precocial and therefore have relatively well-developed feeding behavior. The role of hypothalamic neuropeptides in food-intake regulation in chicks has been reported for decades. However, we hypothesized that nutrients and their metabolites in the brain may be involved in food intake in chicks because these animals exhibit a very frequent feeding pattern. Therefore, the purpose of this study was to examine the feeding behavior of chicks as well as the associated changes in free amino acid and monoamine concentrations in the chick brain. The feeding behavior of chicks was recorded continuously for 6 h. The next day, brain and blood samples were collected when the chicks either attempted to have food (hungry group) or turned food down (satiated group), in order to analyze the concentrations of the free amino acids and monoamines. We confirmed that the feeding behavior of neonatal chicks was characterized by short resting periods between very brief times spent on food intake. Several free amino acids in the mesencephalon were significantly lower in the satiated group than in the hungry group, while l-histidine and l-glutamine were significantly higher. Notably, there was no change in the free amino acid concentrations in other brain regions or plasma. As for monoamines, serotonin and norepinephrine were significantly lower in the mesencephalon of the hungry group compared with the satiated group, but 5 hydroxyindolacetic acid (5-HIAA) was higher. In addition, serotonin and norepinephrine levels were significantly higher in the brain stem of the hungry chicks compared with the satiated group, but levels of 5-HIAA and homovanillic acid were lower. Levels of both dopamine and its metabolite, 3,4-dihydroxyphenylacetic acid, were significantly higher in the diencephalon and telencephalon of the chicks in the hungry group. In conclusion, the changes in the free amino acids and monoamines in the brain may have some role in the feeding behavior of

  9. Parameters of the plasma of a dc pulsating discharge in a supersonic air flow

    Energy Technology Data Exchange (ETDEWEB)

    Shibkov, V. M., E-mail: shibkov@phys.msu.ru; Shibkova, L. V.; Logunov, A. A. [Moscow State University, Faculty of Physics (Russian Federation)

    2017-03-15

    A dc discharge in a cold (T = 200 K) supersonic air flow at a static pressure of 200–400 Torr was studied experimentally. The excited unsteady pulsating discharge has the form of a thin plasma channel with a diameter of ≤1 mm, stretched downstream the flow. Depending on the discharge current, the pulsation frequency varies from 800 to 1600 Hz and the electron temperature varies from 8000 to 15000 K.

  10. Latitude-independent Pc5 Geomagnetic Pulsations Associated With Field Line Resonance

    Science.gov (United States)

    Sung, S.; Kim, K.; Lee, D.; Cattell, C. A.; Andre, M.; Khotyaintsev, Y. V.

    2004-12-01

    The latitude-independent Pc5 pulsations with a spectral peak at ˜2.8 mHz were observed with IMAGE and SAMNET magnetometer array in the morning sector (0700-1000 local time) on April 29 (Day 119), 2001. The spectral amplitude had a local peak at ˜67° geomagnetic latitude, where a sudden phase change of ˜180° appeared. A vortical equivalent ionospheric current structure centered at latitude between 67° and 71° was observed during the Pc5 pulsations and the rotational sense of the current vortex was reversed for one cycle of the pulsation. During the interval of the enhancement of the Pc5 pulsations, the POLAR spacecraft in the morning side crossed near the magnetic shell (L ˜ 8) corresponding to the latitude where the spectral amplitude was maximum, and observed ˜2.8 mHz pulsations in the radial electric field and compressional magnetic field components. Since the toroidal mode Alfvén waves in the magnetosphere are characterized by an electric field perturbation in the radial direction, the simultaneous presence of the pulsations in both components indicates that a field line resonance (FLR) was driven by compressional Pc5 pulsations. Using solar wind data, we conformed that the compressional Pc5 pulsations at POLAR occurred during an interval of enhanced solar wind dynamic pressure. From the analysis of the ground magnetometer data and POLAR data, we suggest that latitude independent ground magnetic perturbations are caused by the vortical equivalent current generated by FLR-associated field-aligned currents.

  11. Embryonic Heart Progenitors and Cardiogenesis

    Science.gov (United States)

    Brade, Thomas; Pane, Luna S.; Moretti, Alessandra; Chien, Kenneth R.; Laugwitz, Karl-Ludwig

    2013-01-01

    The mammalian heart is a highly specialized organ, comprised of many different cell types arising from distinct embryonic progenitor populations during cardiogenesis. Three precursor populations have been identified to contribute to different myocytic and nonmyocytic cell lineages of the heart: cardiogenic mesoderm cells (CMC), the proepicardium (PE), and cardiac neural crest cells (CNCCs). This review will focus on molecular cues necessary for proper induction, expansion, and lineage-specific differentiation of these progenitor populations during cardiac development in vivo. Moreover, we will briefly discuss how the knowledge gained on embryonic heart progenitor biology can be used to develop novel therapeutic strategies for the management of congenital heart disease as well as for improvement of cardiac function in ischemic heart disease. PMID:24086063

  12. The birth of embryonic pluripotency

    OpenAIRE

    Boroviak, Thorsten; Nichols, Jennifer

    2014-01-01

    This is the final published version. It first appeared at http://rstb.royalsocietypublishing.org/content/369/1657/20130541. Formation of a eutherian mammal requires concurrent establishment of embryonic and extraembryonic lineages. The functions of the trophectoderm and primitive endoderm are to enable implantation in the maternal uterus, axis specification and delivery of nutrients. The pluripotent epiblast represents the founding cell population of the embryo proper, which is...

  13. Analysis on observational results of Pi2 geomagnetic pulsation in Henan region

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A measurement profile consisted of 5 sites from Xinyang to Tangyin in Henan Province was set up in September of 1996 to carry out simultaneous observation of Pi2 geomagnetic pulsations. Simultaneity of Pi2 geomagnetic pulsation occurrence along the N-S profile was investigated. Results of analysis pointed out that Pi2 geomagnetic pulsations appeared at first at the site of Xinyang at the southern end of the profile, the later the same Pi2 geomagnetic pulsation appeared, the more north the site was at. Apparent propagation speed of Pi2 in N-S direction in the region is about 140 km/s. Because Pi2 geomagnetic pulsation varying with time is of instability, and based on characteristics that basic wavelet can be dilated and localized, we selected proper basic wavelet form and by means of wavelet transform to analyze the changes of periods and amplitudes of main periodic components included in Pi2 pulsations with time. The results show that there existed complex form in periods and amplitudes of wavelet varying with time.

  14. A second case of outbursts in a pulsating white dwarf observed by Kepler

    CERN Document Server

    Hermes, J J; Bell, Keaton J; Chote, P; Gaensicke, B T; Kawaler, Steven D; Clemens, J C; Dunlap, B H; Winget, D E; Armstrong, D J

    2015-01-01

    We present observations of a new phenomenon in pulsating white dwarf stars: large-amplitude outbursts at timescales much longer than the pulsation periods. The cool (Teff = 11,010 K), hydrogen-atmosphere pulsating white dwarf PG 1149+057 was observed nearly continuously for more than 78.8 d by the extended Kepler mission in K2 Campaign 1. The target showed 10 outburst events, recurring roughly every 8 d and lasting roughly 15 hr, with maximum flux excursions up to 45% in the Kepler bandpass. We demonstrate that the outbursts affect the pulsations and therefore must come from the white dwarf. Additionally, we argue that these events are not magnetic reconnection flares, and are most likely connected to the stellar pulsations and the relatively deep surface convection zone. PG 1149+057 is now the second cool pulsating white dwarf to show this outburst phenomenon, after the first variable white dwarf observed in the Kepler mission, KIC 4552982. Both stars have the same effective temperature, within the uncertain...

  15. The possible statistical relation of Pc1 pulsations to Earthquake occurrence at low latitudes

    Directory of Open Access Journals (Sweden)

    J. Bortnik

    2008-09-01

    Full Text Available We examine the association between earthquakes and Pc1 pulsations observed at a low-latitude station in Parkfield, California. The period under examination is ~7.5 years in total, from February 1999 to July 2006, and we use an automatic identification algorithm to extract information on Pc1 pulsations from the magnetometer data. These pulsations are then statistically correlated to earthquakes from the USGS NEIC catalog within a radius of 200 km around the magnetometer, and M>3.0. Results indicate that there is an enhanced occurrence probability of Pc1 pulsations ~5–15 days in advance of the earthquakes, during the daytime. We quantify the statistical significance and show that such an enhancement is unlikely to have occurred due to chance alone. We then examine the effect of declustering our earthquake catalog, and show that even though significance decreases, there is still a statistically significant daytime enhancement prior to the earthquakes. Finally, we select only daytime Pc1 pulsations as the fiducial time of our analysis, and show that earthquakes are ~3–5 times more likely to occur in the week following these pulsations, than normal. Comparing these results to other events, it is preliminarily shown that the normal earthquake probability is unaffected by geomagnetic activity, or a random event sequence.

  16. Generation of different long-period geomagnetic pulsations during a sudden impulse

    Science.gov (United States)

    Moiseyev, A. V.; Popov, V. I.; Mullayarov, V. A.; Samsonov, S. N.; Du, A.; Yoshikawa, A.

    2015-07-01

    The space-time characteristics of geomagnetic pulsations during a sudden impulse on August 4, 2010 have been analyzed using ground-based and satellite observations. It has been indicated that two types of geomagnetic pulsations with different spatial extensions, oscillation frequencies, and generations were observed at that time. It has been found that geomagnetic pulsations with identical oscillation frequencies (˜4.5 mHz) at different latitudes were observed, with a maximal amplitude in the dusk sector. Oscillations with close frequencies were registered in the solar wind in the IMF B z component. Higher-frequency (7-10 mHz) pulsations dependent on latitude were registered on the dawn side. It is assumed that geomagnetic pulsations with frequencies of ˜4.5 mHz were caused by oscillations penetrating from the interplanetary medium, and higher-frequency pulsations were Alfvén resonance oscillations generated during the compression of the magnetosphere. An asymmetric oscillation amplitude distribution relative to noon was caused by the IMF orthospiral orientation in this event.

  17. Evaluation of runner cone extension to dampen pressure pulsations in a Francis model turbine

    Science.gov (United States)

    Gogstad, Peter Joachim; Dahlhaug, Ole Gunnar

    2016-11-01

    Today's energy market has a high demand of flexibility due to introduction of other intermittent renewables as wind and solar. To ensure a steady power supply, hydro turbines are often forced to operate more at part load conditions. Originally, turbines were built for steady operation around the best efficiency point. The demand of flexibility, combined with old designs has showed an increase in turbines having problems with hydrodynamic instabilities such as pressure pulsations. Different methods have been investigated to mitigate pressure pulsations. Air injection shows a significant reduction of pressure pulsation amplitudes. However, installation of air injection requires extra piping and a compressor. Investigation of other methods such as shaft extension shows promising results for some operational points, but may significantly reduce the efficiency of the turbine at other operational points. The installation of an extension of the runner cone has been investigated at NTNU by Vekve in 2004. This has resulted in a cylindrical extension at Litjfossen Power Plant in Norway, where the bolt suffered mechanical failure. This indicates high amplitude pressure pulsations in the draft tube centre. The high pressure pulsation amplitudes are believed to be related to high tangential velocity in the draft tube. The mentioned runner cone extension has further been developed to a freely rotating extension. The objective is to reduce the tangential velocity in the draft tube and thereby the pressure pulsation amplitudes.

  18. Blue straggler masses from pulsation properties. II. Topology of the Instability Strip

    CERN Document Server

    Fiorentino, G; Bono, G; Dalessandro, E; Ferraro, F R; Lanzoni, B; Lovisi, L; Mucciarelli, A

    2015-01-01

    We present a new set of nonlinear, convective radial pulsation models for main sequence stars computed assuming three metallicities: Z=0.0001, 0.001 and 0.008. These chemical compositions bracket the metallicity of stellar systems hosting SX Phoenicis stars (SXPs or pulsating Blue Stragglers), namely Galactic globular clusters and nearby dwarf spheroidals. Stellar masses and luminosities of the pulsation models are based on alpha--enhanced evolutionary tracks from the BASTI website. We are able to define the topology of the instability strip (IS), and in turn the pulsation relations for the first four pulsation modes. We found that third overtones approach a stable nonlinear limit cycle. Predicted and empirical IS agree quite well in the case of 49 SXPs belonging to omega Cen. We used theoretical Period-Luminosity relations in B,V bands to identify their pulsation mode. We assumed Z=0.001 and Z=0.008 as mean metallicities of SXPs in omega Cen. We found respectively 13-15 fundamental, 22-6 first and 9-4 second...

  19. The pulsation modes of the pre-white dwarf PG 1159-035

    CERN Document Server

    Costa, J E S; Winget, D E; O'Brien, M S; Kawaler, S D; Costa, A F M; Giovannini, O; Kanaan, A; Mukadam, A S; Mullally, F; Nitta, A; Provençal, J L; Shipman, H; Wood, M A; Ahrens, T J; Grauer, A; Kilic, M; Bradley, P A; Sekiguchi, K; Crowe, R; Jiang, X J; Sullivan, D; Sullivan, T; Rosen, R; Clemens, J C; Janulis, R; O'Donoghue, D; Ogloza, W; Baran, A; Silvotti, R; Marinoni, S; Vauclair, G; Dolez, N; Chevreton, M; Dreizler, S; Schuh, S; Deetjen, J; Nagel, T; Solheim, J -E; Perez, J M Gonzalez; Ulla, A; Barstow, Martin; Burleigh, M; Good, S; Metcalfe, T S; Kim, S -L; Lee, H; Sergeev, A; Akan, M C; Çakirli, Ö; Paparo, M; Viraghalmy, G; Ashoka, B N; Handler, G; Hürkal, Özlem; Johannessen, F; Kleinman, S J; Kalytis, R; Krzesínski, J; Klumpe, E; Larrison, J; Lawrence, T; Mestas, E; Martínez, P; Nather, R E; Fu, J -N; Pakstien, E; Rosen, R; Romero-Colmenero, E; Riddle, R; Seetha, S; Silvestri, N M; Vuckovic, M; Warner, B; Zola, S; Althaus, L G; Córsico, A H; Montgomery, M H

    2007-01-01

    PG 1159-035, a pre-white dwarf with T_eff=140,000 K, is the prototype of both two classes: the PG1159 spectroscopic class and the DOV pulsating class. Previous studies of PG 1159-035 photometric data obtained with the Whole Earth Telescope (WET) showed a rich frequency spectrum allowing the identification of 122 pulsation modes. In this work, we used all available WET photometric data from 1983, 1985, 1989, 1993 and 2002 to identify the pulsation periods and identified 76 additional pulsation modes, increasing to 198 the number of known pulsation modes in PG 1159-035, the largest number of modes detected in any star besides the Sun. From the period spacing we estimated a mass M = 0.59 +/- 0.02 solar masses for PG 1159-035, with the uncertainty dominated by the models, not the observation. Deviations in the regular period spacing suggest that some of the pulsation modes are trapped, even though the star is a pre-white dwarf and the gravitational settling is ongoing. The position of the transition zone that cau...

  20. Analysis of Pressure Pulsation Induced by Rotor-Stator Interaction in Nuclear Reactor Coolant Pump

    Directory of Open Access Journals (Sweden)

    Xu Zhang

    2017-01-01

    Full Text Available The internal flow of reactor coolant pump (RCP is much more complex than the flow of a general mixed-flow pump due to high temperature, high pressure, and large flow rate. The pressure pulsation that is induced by rotor-stator interaction (RSI has significant effects on the performance of pump; therefore, it is necessary to figure out the distribution and propagation characteristics of pressure pulsation in the pump. The study uses CFD method to calculate the behavior of the flow. Results show that the amplitudes of pressure pulsation get the maximum between the rotor and stator, and the dissipation rate of pressure pulsation in impellers passage is larger than that in guide vanes passage. The behavior is associated with the frequency of pressure wave in different regions. The flow rate distribution is influenced by the operating conditions. The study finds that, at nominal flow, the flow rate distribution in guide vanes is relatively uniform and the pressure pulsation amplitude is the smallest. Besides, the vortex shedding or backflow from the impeller blade exit has the same frequency as pressure pulsation but there are phase differences, and it has been confirmed that the absolute value of phase differences reflects the vorticity intensity.

  1. Induction of an antimicrobial biotin-binding egg white protein (avidin) in chick tissues in septic Escherichia coli infection.

    Science.gov (United States)

    Elo, H A; Räisänen, S; Tuohimaa, P J

    1980-03-15

    The induction of avidin in chick tissues was found in septic Escherichia coli infection. Avidin concentrations in the plasma roughly corresponded to those in the other tissues studied which suggests that avidin in chicks is a secretory protein.

  2. A descriptive study to provide evidence of the teratogenic and cellular effects of sibutramine and ephedrine on cardiac- and liver-tissue of chick embryos.

    Science.gov (United States)

    Oberholzer, Hester Magdalena; Van Der Schoor, Ciska; Taute, Helena; Bester, Megan Jean

    2015-08-01

    Exposure to drugs during pregnancy is a major concern, as some teratogenic compounds can influence normal foetal development. Although the use of drugs during pregnancy should generally be avoided, exposure of the developing foetus to teratogens may occur unknowingly since these compounds may be hidden in products that are being marketed as "all natural." The aim of the current study was to investigate the possible teratogenic and cellular effects of sibutramine-a serotonin-norepinephrine reuptake inhibitor used in the treatment of obesity-on the heart and liver tissue of chick embryos. Ephedrine was used as a positive control. The chick embryo model was chosen because it has been used in studying developmental and experimental biology and teratology with great success. The embryos were exposed to three different concentrations of sibutramine and ephedrine respectively. The results obtained revealed that both compounds exhibited embryotoxicity when compared to the control groups. Liver and heart tissue of the exposed embryos was severely affected by these compounds in a dose-related manner. Morphology similar to that of muscle dystrophy was observed in the heart, where the muscle tissue was infiltrated by adipose and connective tissue. Severe liver steatosis was also noted. A more in-depth investigation into the molecular pathways involved might provide more information on the exact mechanism of toxicity of these products influencing embryonic development.

  3. Ectopic Myf5 or MyoD prevents the neuronal differentiation program in addition to inducing skeletal muscle differentiation, in the chick neural tube.

    Science.gov (United States)

    Delfini, Marie-Claire; Duprez, Delphine

    2004-02-01

    Forced expression of the bHLH myogenic factors, Myf5 and MyoD, in various mammalian cell lines induces the full program of myogenic differentiation. However, this property has not been extensively explored in vivo. We have taken advantage of the chick model to investigate the effect of electroporation of the mouse Myf5 and MyoD genes in the embryonic neural tube. We found that misexpression of either mouse Myf5 or MyoD in the chick neural tube leads to ectopic skeletal muscle differentiation, assayed by the expression of the myosin heavy chains in the neural tube and neural crest derivatives. We also showed that the endogenous neuronal differentiation program is inhibited under the influence of either ectopic mouse Myf5 or MyoD. We used this new system to analyse, in vivo, the transcriptional regulation between the myogenic factors. We found that MyoD and Myogenin expression can be activated by ectopic mouse Myf5 or MyoD, while Myf5 expression cannot be activated either by mouse MyoD or by itself. We also analysed the transcriptional regulation between the myogenic factors and the different genes involved in myogenesis, such as Mef2c, Pax3, Paraxis, Six1, Mox1, Mox2 and FgfR4. We established the existence of an unexpected regulatory loop between MyoD and FgfR4. The consequences for myogenesis are discussed.

  4. Nitric oxide drives embryonic myogenesis in chicken through the upregulation of myogenic differentiation factors.

    Science.gov (United States)

    Cazzato, Denise; Assi, Emma; Moscheni, Claudia; Brunelli, Silvia; De Palma, Clara; Cervia, Davide; Perrotta, Cristiana; Clementi, Emilio

    2014-01-15

    The muscle-specific variant of neuronal nitric oxide (NO) synthase (NOS-I), is developmentally regulated in mouse suggesting a role of NO during myogenesis. In chick embryo, a good model of development, we found that the expression of NOS-I is up-regulated, but only in the early phase of development. Through a pharmacological intervention in ovo we found that NO signalling plays a relevant role during embryonic development. The inhibition of NOS-I decreased the growth of embryo, in particular of muscle tissue, while the restoring of physiological NO levels, via administration of a NO donor, reversed this effect. We found a selective action of NO, produced by NOS-I, on regulatory factors involved in myogenic differentiation in the early phase of chick embryo development: inhibition of NO generation leads to a decreased expression of the Myocyte enhancer factor 2a (Mef2a), Mef2c, Myogenin and Myosin, which was reversed by the administration of a NO donor. NO had no effects on Myf5 and MyoD, the myogenic regulatory factors necessary for myogenic determination. The action of NO on the myogenic regulatory factors was mediated via generation of cyclic GMP (cGMP) and activation of the cGMP-dependent protein kinase G (PKG). Finally we found in myoblasts in vitro that the activation of Mef2c was the key event mediating the NO-induced modulation of myogenesis. Our results identify NO produced by NOS-I as a key messenger in the early phase of embryonic development of chicken, acting as a critical determinant of myogenesis through its physiological cGMP/PKG pathway.

  5. EFFECTS OF PRIMARY IMPRINTING ON THE SUBSEQUENT DEVELOPMENT OF SECONDARY FILIAL ATTACHMENTS IN THE CHICK

    NARCIS (Netherlands)

    DEVOS, GJ; VANKAMPEN, HS

    This study reinvestigates the effects of primary imprinting of chicks with either a naturalistic stimulus or an artificial object on subsequent imprinting with artificial objects. Initial experience with a live chick (group C) or a yellow cylinder (group Y) had differential effects on the

  6. Short communication: hippocampal neuronal activity and imprinting in the behaving domestic chick.

    Science.gov (United States)

    Nicol, A U; Brown, M W; Horn, G

    1998-08-01

    The hippocampus of the chick projects to the intermediate and medial part of the hyperstriatum ventrale (IMHV) which stores information acquired through the learning process of imprinting. We have investigated whether the response properties of hippocampal neurons are similar to those of IMHV neurons. Chicks were imprinted by exposure, one group (n = 7) to a rotating red box (RB), the other (n = 5) to a rotating blue cylinder (BC). Four chicks were untrained. The following day, when the chicks were approximately 48 h old, neuronal activity was recorded in the left hippocampus. The proportion of neurons responding to the RB and that to the BC in untrained chicks were compared with the proportions in trained birds. (i) In RB-trained chicks both the proportion responding to the RB and that to the BC were significantly increased. (ii) In BC-trained chicks no significant effect on these proportions was found. Of the responsive neurons some were colour (red or blue) sensitive and others were shape (box or cylinder) sensitive; the proportions so responsive were not influenced by training condition. Certain neurons responded significantly differently when a stimulus was 0.5 m or 2 m from the chick (35%; d-sensitive); very few neurons were equivalently responsive to a stimulus at both distances (3%; d-invariant). These proportions were not significantly affected by training condition. Hippocampal responses are compared with those in the left IMHV. It is concluded that IMHV responses do not passively reflect those of hippocampal neurons.

  7. Study of the infectivity of saline-stored Campylobacter jejuni for day-old chicks

    DEFF Research Database (Denmark)

    Hald, Birthe; Knudsen, Katrine; Lind, Peter

    2001-01-01

    The culturability of three Campylobacter jejuni strains and their infectivity for day-old chicks were assessed following storage of the strains in saline. The potential for colonization of chicks was weakened during the storage period and terminated 3 to 1 weeks before the strains became...

  8. Classification of neuromuscular blocking agents in a new neuromuscular preparation of the chick in vitro

    NARCIS (Netherlands)

    Riezen, H. van

    1968-01-01

    A neuromuscular preparation of the chick is described: 1. 1. The sciatic nerve-tibilis anterior muscle preparation of the 2–10 days old chick fulfils all criteria of an assay preparation and differentiates between curare-like and decamethonium-like agents. 2. 2. The preparation responds to

  9. EFFECTS OF PRIMARY IMPRINTING ON THE SUBSEQUENT DEVELOPMENT OF SECONDARY FILIAL ATTACHMENTS IN THE CHICK

    NARCIS (Netherlands)

    DEVOS, GJ; VANKAMPEN, HS

    1993-01-01

    This study reinvestigates the effects of primary imprinting of chicks with either a naturalistic stimulus or an artificial object on subsequent imprinting with artificial objects. Initial experience with a live chick (group C) or a yellow cylinder (group Y) had differential effects on the developmen

  10. Foraging behavior and physiological changes in precocial quail chicks in response to low temperatures

    NARCIS (Netherlands)

    Krijgsveld, KL; Visser, GH; Daan, S

    2003-01-01

    We examined whether low ambient temperatures influence foraging behavior of precocial Japanese quail chicks and alter the balance between investment in growth and thermogenic function. To test this, one group of chicks was exposed to 7 degreesC and one group to 24 degreesC during foraging throughout

  11. Efficiency of several cultural methods and a chick bioassay to recover dry stressed Campylobacter

    Science.gov (United States)

    The aims of the study were to evaluate the efficacy of 5 enrichment procedures for recovery of dry-atmospheric-temperature stressed C. jejuni and C. coli and determine the viable status of the non-culturable strains using a chick bioassay. Sterile chick paper pads (PP) and filter papers (FP) were i...

  12. Influences of Feeding Lactobacillus on Colonization of the Lactobacillus in Chicks'Digestible Tracts

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    It was carried out with culture solution of Lactobacillus fed to the newborn chicks to observe the influences on colonization of the Lactobacillus in chicks′ digestible tracts. The results showed that after the chicks were fed Lactobacillus, the amount of the Lactobacillus in chicks′ digestible tracts significantly increased (P<0.01) and the Lactobacillus colonized 36h ahead of schedule

  13. Effects of in ovo injection of carbohydrates on embryonic metabolism, hatchability, and subsequent somatic characteristics of broiler hatchlings.

    Science.gov (United States)

    Zhai, W; Gerard, P D; Pulikanti, R; Peebles, E D

    2011-10-01

    The effects of the in ovo injection of different carbohydrate solutions on the internal egg temperature (IT), hatchability, and time of hatch of embryonated Ross × Ross 708 broiler hatching eggs were determined. In addition, the BW, liver weight, yolk sac weight (YSW), and yolk-free BW (YFBW) of the embryos on d 19.5 of incubation and of the chicks on day of hatch were determined. Eggs containing live embryos were injected in the amnion on d 18.5 of incubation using an automated multiple-egg injector. Solution injections delivered 1.2 mL of physiological saline (0.85%) alone or with a supplemental carbohydrate. The following supplemental carbohydrates were separately dissolved in saline at a concentration of 0.3 g/mL: glucose, fructose, sucrose, maltose, and dextrin. Temperature transponders were implanted in the air cells of embryonated and nonembryonated eggs after in ovo injection for the detection of IT at 6, 14, and 22 h after injection. The IT of embryonated eggs was significantly greater than that of nonembryonated eggs at all 3 times after the treatment period. Eggs that were injected with saline with or without supplemental carbohydrates experienced a reduction in IT when compared with control eggs whose shells were perforated without solution delivery, and the decrease in IT was associated with a delay in hatch time. Liver weight was negatively related to YSW and positively related to YFBW, and YSW was negatively related to YFBW. Although the saline and carbohydrate solution injections increased chick BW compared with noninjected controls, chick YFBW was decreased in the maltose- and sucrose-injected groups. In conclusion, the injection of 1.2 mL of saline with or without supplemental carbohydrates lowered embryonic metabolism, as reflected by a lower IT and a delay in time of hatch. However, effects of the different carbohydrate solutions on yolk absorption and tissue deposition in yolk-free embryos varied. These results suggest that lower volumes for

  14. Imprinted Numbers: Newborn Chicks' Sensitivity to Number vs. Continuous Extent of Objects They Have Been Reared with

    Science.gov (United States)

    Rugani, Rosa; Regolin, Lucia; Vallortigara, Giorgio

    2010-01-01

    Newborn chicks were tested for their sensitivity to number vs. continuous physical extent of artificial objects they had been reared with soon after hatching. Because of the imprinting process, such objects were treated by chicks as social companions. We found that when the objects were similar, chicks faced with choices between 1 vs. 2 or 2 vs. 3…

  15. Protection of non-immunized broiler chicks housed with immunized cohorts against infection with Eimeria maxima and E. acervulina

    Science.gov (United States)

    The use of live oocyst vaccines is becoming increasingly important in the control of avian coccidosis in broiler chicks. Knowledge of the mechanisms of how chicks uptake oocysts and become immune is important for optimizing delivery of live vaccines. The current study tests the hypothesis that chick...

  16. Experimental and Theoretical Studies of Pulsating Turbulent Flow. Ph.D. Thesis

    Science.gov (United States)

    Kingston, G. C.

    1975-01-01

    The objective of this investigation was to study the effects of small amplitude sinusoidal pulsations on fully developed turbulent flow in a tube from both experimental and theoretical viewpoints. Theoretical models for the macroscopic behavior of pulsating turbulent tube flow were developed for the two cases of very low and very high pulsation frequencies. The models are based on assumptions of quasi-steady and frozen eddy viscosity flow behavior, respectively. The models successfully predict unsteady velocity profiles, thereby supporting the currently proposed definitions of frequency regimes in pulsating turbulent flow. Experimental measurements were made of the time-dependent pressure drop and velocity profiles over the range of frequency-to-Reynolds number ratios from 0.0095 to 0.24. The two macroscopic models developed in this study predict unsteady velocity profiles which are in moderately good agreement with the experiments in their respective frequency regimes, and a previously developed quasi-steady model is found to predict experimental velocity profiles well in both the quasisteady and the frozen eddy viscosity frequency regimes. The effect of flow pulsations on the dissipation of turbulence energy in the vicinity of the wall was measured in the lower transition frequency regime. The long-time averaged dissipation was observed to be unchanged from the steady flow dissipation, within the accuracy of the experiment. A theoretical model of the periodic viscous sublayer was also developed and applied to pulsating flow in a tube, in order to investigate the effects of flow pulsations on the rate of production of turbulence in the region of the wall. The periodic viscous sublayer model predicts sublayer growth periods in steady flow which agree with the published experimental data. When the model is applied to pulsating flow, the response of the sublayer growth period falls into three frequency regimes, the parameters of which are in approximate agreement

  17. PULSATION PERIOD VARIATIONS IN THE RRc LYRAE STAR KIC 5520878

    Energy Technology Data Exchange (ETDEWEB)

    Hippke, Michael [Institute for Data Analysis, Luiter Str. 21b, D-47506 Neukirchen-Vluyn (Germany); Learned, John G. [High Energy Physics Group, Department of Physics and Astronomy, University of Hawaii, Manoa 327 Watanabe Hall, 2505 Correa Road, Honolulu, HI 96822 (United States); Zee, A. [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Edmondson, William H. [School of Computer Science, University of Birmingham, Birmingham B15 2TT (United Kingdom); Lindner, John F. [Physics Department, The College of Wooster, Wooster, OH 44691 (United States); Kia, Behnam; Ditto, William L. [Department of Physics and Astronomy, University of Hawai' i at Mānoa, Honolulu, HI 96822 (United States); Stevens, Ian R., E-mail: hippke@ifda.eu, E-mail: jgl@phys.hawaii.edu, E-mail: zee@kitp.ucsb.edu, E-mail: w.h.edmondson@bham.ac.uk, E-mail: jlindner@wooster.edu, E-mail: wditto@hawaii.edu, E-mail: behnam@hawaii.edu, E-mail: irs@star.sr.bham.ac.uk [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2015-01-01

    Learned et al. proposed that a sufficiently advanced extra-terrestrial civilization may tickle Cepheid and RR Lyrae variable stars with a neutrino beam at the right time, thus causing them to trigger early and jogging the otherwise very regular phase of their expansion and contraction. This would turn these stars into beacons to transmit information throughout the galaxy and beyond. The idea is to search for signs of phase modulation (in the regime of short pulse duration) and patterns, which could be indicative of intentional, omnidirectional signaling. We have performed such a search among variable stars using photometric data from the Kepler space telescope. In the RRc Lyrae star KIC 5520878, we have found two such regimes of long and short pulse durations. The sequence of period lengths, expressed as time series data, is strongly autocorrelated, with correlation coefficients of prime numbers being significantly higher (p = 99.8%). Our analysis of this candidate star shows that the prime number oddity originates from two simultaneous pulsation periods and is likely of natural origin. Simple physical models elucidate the frequency content and asymmetries of the KIC 5520878 light curve. Despite this SETI null result, we encourage testing of other archival and future time-series photometry for signs of modulated stars. This can be done as a by-product to the standard analysis, and can even be partly automated.

  18. Quasiperiodic ULF-pulsations in Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. Kleindienst

    2009-02-01

    Full Text Available Recent magnetic field investigations made onboard the Cassini spacecraft in the magnetosphere of Saturn show the existence of a variety of ultra low frequency plasma waves. Their frequencies suggest that they are presumably not eigenoscillations of the entire magnetospheric system, but excitations confined to selected regions of the magnetosphere. While the main magnetic field of Saturn shows a distinct large scale modulation of approximately 2 nT with a periodicity close to Saturn's rotation period, these ULF pulsations are less obvious superimposed oscillations with an amplitude generally not larger than 3 nT and show a package-like structure. We have analyzed these wave packages and found that they are correlated to a certain extent with the large scale modulation of the main magnetic field. The spatial localization of the ULF wave activity is represented with respect to local time and Kronographic coordinates. For this purpose we introduce a method to correct the Kronographic longitude with respect to a rotation period different from its IAU definition. The observed wave packages occur in all magnetospheric regions independent of local time, elevation, or radial distance. Independent of the longitude correction applied the wave packages do not occur in an accentuated Kronographic longitude range, which implies that the waves are not excited or confined in the same selected longitude ranges at all times or that their lifetime leads to a variable phase with respect to the longitudes where they have been exited.

  19. A helium based pulsating heat pipe for superconducting magnets

    Science.gov (United States)

    Fonseca, Luis Diego; Miller, Franklin; Pfotenhauer, John

    2014-01-01

    This study was inspired to investigate an alternative cooling system using a helium-based pulsating heat pipes (PHP), for low temperature superconducting magnets. In addition, the same approach can be used for exploring other low temperature applications. The advantages of PHP for transferring heat and smoothing temperature profiles in various room temperature applications have been explored for the past 20 years. An experimental apparatus has been designed, fabricated and operated and is primarily composed of an evaporator and a condenser; in which both are thermally connected by a closed loop capillary tubing. The main goal is to measure the heat transfer properties of this device using helium as the working fluid. The evaporator end of the PHP is comprised of a copper winding in which heat loads up to 10 watts are generated, while the condenser is isothermal and can reach 4.2 K via a two stage Sumitomo RDK408A2 GM cryocooler. Various experimental design features are highlighted. Additionally, performance results in the form of heat transfer and temperature characteristics are provided as a function of average condenser temperature, PHP fill ratio, and evaporator heat load. Results are summarized in the form of a dimensionless correlation and compared to room temperature systems. Implications for superconducting magnet stability are highlighted.

  20. SMEI observations of previously unseen pulsation frequencies in gamma Doradus

    CERN Document Server

    Tarrant, N J; Elsworth, Y P; Spreckley, S A; Stevens, I R

    2008-01-01

    Aims: As g-mode pulsators, gamma-Doradus-class stars may naively be expected to show a large number of modes. Taking advantage of the long photometric time-series generated by the Solar Mass Ejection Imager (SMEI) instrument, we have studied the star gamma Doradus to determine whether any other modes than the three already known are present at observable amplitude. Methods: High-precision photometric data from SMEI taken between April 2003 and March 2006 were subjected to periodogram analysis with the PERIOD04 package. Results: We confidently determine three additional frequencies at 1.39, 1.87, and 2.743 cycles per day. These are above and beyond the known frequencies of 1.320, 1.364, and 1.47 cycles per day. Conclusions: Two of the new frequencies, at 1.39 and 1.87 cycles per day, are speculated to be additional modes of oscillation, with the third frequency at 2.743 cycles per day a possible combination frequency.

  1. Variability and pulsations in the Be star 66 Ophiuchi

    Science.gov (United States)

    Floquet, M.; Neiner, C.; Janot-Pacheco, E.; Hubert, A. M.; Jankov, S.; Zorec, J.; Briot, D.; Chauville, J.; Leister, N. V.; Percy, J. R.; Ballereau, D.; Bakos, A. G.

    2002-10-01

    66 Oph is a Be star seen under a moderate inclination angle that shows strong variability from UV to IR wavelengths. A concise review of long-term variability history is given. High resolution, high S/N spectroscopic observations obtained in 1997, 1998 and 2001 and spectropolarimetric observations obtained in 2000 are presented. These observations occurred during a long-term decrease of Hα intensity. Fundamental parameters of the star have been revisited from Barbier-Chalonge-Divan (BCD) calibrations. New V sin i values are obtained using Fourier transforms applied to observed helium lines and a rotational frequency f_rot = 1.29 c d-1 is determined. Time series analysis and Fourier Doppler Imaging (FDI) of He I lines (4713, 4921, 5876 and 6678 Å) lead for the first time to the detection of multi-periodicity in 66 Oph. The two main frequencies found are f = 2.22 c d-1 and f = 4.05 c d-1 . They are attributed to non-radial pulsations and can be associated with mode degree l = 2 and l = 3, respectively. Inspection of Stokes V profiles suggests the presence of a weak Zeeman signature but further observations are needed to confirm the detection of a magnetic field in 66 Oph. Based on observations taken at OHP and Pic du Midi Observatory (France), at MBT/LNA (Brazil) and on Brazilian observing time at La Silla (ESO, Chile).

  2. Mass flow and its pulsation measurements in supersonic wing wake

    Science.gov (United States)

    Shmakov, A. S.; Shevchenko, A. M.; Yatskikh, A. A.; Yermolaev, Yu. G.

    2016-10-01

    The results of experimental study of the flow in the wing wake are presented. Experiments were carried out in supersonic wind tunnel T-325 of ITAM SB RAS. Rectangle half-wing with sharp edges with a chord length of 30 mm and semispan of 95 mm was used to generate vortex wake. Experimental data were obtained in the cross section located 6 chord length downstream of the trailing edge at Mach numbers of 2.5 and 4 and at wing angles of attack of 4 and 10 degrees. Constant temperature hot-wire anemometer was used to measure disturbances in supersonic flow. Hot-wire was made of a tungsten wire with a diameter of 10 μm and length of 1.5 mm. Shlieren flow visualization were performed. As a result, the position and size of the vortex core in the wake of a rectangular wing were determined. For the first time experimental data on the mass flow distribution and its pulsations in the supersonic longitudinal vortex were obtained.

  3. Soft X-ray Pulsations in Solar Flares

    CERN Document Server

    Simões, Paulo J A; Fletcher, Lyndsay

    2014-01-01

    The soft X-ray emissions of solar flares come mainly from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy, although the bulk of the total flare energy goes elsewhere. Recently Dolla et al. (2012) noted quasi-periodic pulsations (QPP) in the soft X-ray signature of the X-class flare SOL2011-02-15, as observed by the standard photometric data from the GOES (Geostationary Operational Environmental Satellite) spacecraft. We analyze the suitability of the GOES data for this kind of analysis and find them to be generally valuable after Sept. 2010 (GOES-15). We then extend Dolla et al. results to a list of X-class flares from Cycle 24, and show that most of them display QPP in the impulsive phase. During the impulsive phase the footpoints of the newly-forming flare loops may also contribute to the observed soft X-ray variations. The QPP show up cleanly in both channels of the GOES dat...

  4. Pressure pulsation in Kaplan turbines: Prototype-CFD comparison

    Science.gov (United States)

    Rivetti, A.; Lucino1, C.; Liscia, S.; Muguerza, D.; Avellan, F.

    2012-11-01

    Pressure pulsation phenomena in a large Kaplan turbine are investigated by means of numerical simulations (CFD) and prototype measurements in order to study the dynamic behavior of flow due to the blade passage and its interaction with other components of the turbine. Numerical simulations are performed with the commercial software Ansys CFX code, solving the incompressible Unsteady Reynolds-Averaged-Navier Stokes equations under a finite volume scheme. The computational domain involves the entire machine at prototype scale. Special care is taken in the discretization of the wicket gate overhang and runner blade gap. Prototype measurements are performed using pressure transducers at different locations among the wicket gate outlet and the draft tube inlet. Then, CFD results are compared with temporary signals of prototype measurements at identical locations to validate the numerical model. A detailed analysis was focused on the tip gap flow and the pressure field at the discharge ring. From a rotating reference frame perspective, it is found that the mean pressure fluctuates accordingly the wicket gate passage. Moreover, in prototype measurements the pressure frequency that reveals the presence of modulated cavitation at the discharge ring is distinguished, as also verified from the shape of erosion patches in concordance with the number of wicket gates.

  5. KIC 4552982: outbursts and pulsations in the longest-ever pseudo-continuous light curve of a ZZ Ceti

    Directory of Open Access Journals (Sweden)

    Bell K. J.

    2015-01-01

    Full Text Available KIC 4552982 was the first ZZ Ceti (hydrogen-atmosphere pulsating white dwarf identified to lie in the Kepler field, resulting in the longest pseudo-continuous light curve ever obtained for this type of variable star. In addition to the pulsations, this light curve exhibits stochastic episodes of brightness enhancement unlike any previously studied white dwarf phenomenon. We briefly highlight the basic outburst and pulsation properties in these proceedings.

  6. Precocious locomotor behavior begins in the egg: development of leg muscle patterns for stepping in the chick.

    Directory of Open Access Journals (Sweden)

    Young U Ryu

    Full Text Available BACKGROUND: The chicken is capable of adaptive locomotor behavior within hours after hatching, yet little is known of the processes leading to this precocious skill. During the final week of incubation, chick embryos produce distinct repetitive limb movements that until recently had not been investigated. In this study we examined the leg muscle patterns at 3 time points as development of these spontaneous movements unfolds to determine if they exhibit attributes of locomotion reported in hatchlings. We also sought to determine whether the deeply flexed posture and movement constraint imposed by the shell wall modulate the muscle patterns. METHODOLOGY/PRINCIPAL FINDINGS: Synchronized electromyograms for leg muscles, force and video were recorded continuously from embryos while in their naturally flexed posture at embryonic day (E 15, E18 and E20. We tested for effects of leg posture and constraint by removing shell wall anterior to the foot. Results indicated that by E18, burst onset time distinguished leg muscle synergists from antagonists across a 10-fold range in burst frequencies (1-10 Hz, and knee extensors from ankle extensors in patterns comparable to locomotion at hatching. However, burst durations did not scale with step cycle duration in any of the muscles recorded. Despite substantially larger leg movements after shell removal, the knee extensor was the only muscle to vary its activity, and extensor muscles often failed to participate. To further clarify if the repetitive movements are likely locomotor-related, we examined bilateral coordination of ankle muscles during repetitive movements at E20. In all cases ankle muscles exhibited a bias for left/right alternation. CONCLUSIONS/SIGNIFICANCE: Collectively, the findings lead us to conclude that the repetitive leg movements in late stage embryos are locomotor-related and a fundamental link in the establishment of precocious locomotor skill. The potential importance of differences

  7. Shh regulates chick Ebf1 gene expression in somite development.

    Science.gov (United States)

    El-Magd, Mohammed Abu; Allen, Steve; McGonnell, Imelda; Mansour, Ali A; Otto, Anthony; Patel, Ketan

    2015-01-01

    The chick early B-cell factor 1 (cEbf1) is a member of EBF family of helix loop helix transcription factors. Recently, we have proved that cEbf1 expression in feather is regulated by Shh. It is therefore possible that the somitic expression of cEbf1 is controlled by Shh signals from the notochord. To assess this hypothesis, the expression profile of cEbf1 was first detailed in somites of chick embryos (from HH8 to HH28). cEbf1 expression was mainly localised in the medial sclerotome and later around the vertebral cartilage anlagen of body and pedicles. Tissue manipulations (notochord ablation) and Shh gain and loss of function experiments were then performed to analyse whether the notochord and/or Shh regulate cEbf1 expression. Results from these experiments confirmed our hypothesis that the medial somitic expression of cEbf1 is regulated by Shh from the notochord. In conclusion, cEbf1 gene is considered as a medial sclerotome marker, downstream to and regulated by the notochord derived Shh, which may be functionally involved in somitogenesis.

  8. Aquaporin-1 expression in the chick embryo chorioallantoic membrane.

    Science.gov (United States)

    Ribatti, Domenico; Frigeri, Antonio; Nico, Beatrice; Nicchia, Grazia Paola; De Giorgis, Michela; Roncali, Luisa; Svelto, Maria

    2002-10-01

    The chick embryo chorioallantoic membrane (CAM) is commonly used in vivo to study both angiogenesis and anti-angiogenesis. Rapid membrane water transport is mediated by a family of molecular water channels, called aquaporins (AQPs), which have been identified in the epithelial and endothelial cells of higher vertebrates. AQP1, expressed in adsorptive and secretory epithelia, is also expressed in endothelial cells of capillaries and arteries. Its mRNA has been found in vascular smooth muscle cells (VSMCs) of arteries and capillaries, as well as in a subset of VSMCs of human atherosclerotic plaques. This study investigated the developmental expression of AQP1 in the chick CAM by Western blot and immunohistochemistry. Western blot results show that a major nonglycosylated band was observed with electrophoretic mobility of approximately 28 kDa in the three developmental stages examined. Immunohistochemistry data demonstrate that AQP1 was clearly expressed in the ectodermal and endodermal epithelia, the vascular endothelium, and the VSMCs. Because little information is available on the behavior of microvessel AQP1 during angiogenesis in normal and pathological conditions, our data relative to the pattern of expression of AQP1 in CAM blood vessels in normal conditions may be considered a useful tool to further investigate its modifications in several experimental conditions implying a stimulation or an inhibition of angiogenesis in the CAM assay. Copyright 2002 Wiley-Liss, Inc.

  9. IN VIVO TOXICITY ASSESSMENT OF SILICA NANOPARTICLES IN CHICK EMBRYO

    Directory of Open Access Journals (Sweden)

    Chandrapragasam Vani

    2013-09-01

    Full Text Available Silica is one of the most effective stored seedand food grain protecting pesticide agent, usedfor ages Silica nanoparticles are hard and strong andresistant to brittle fracture under an imposed stress. The aim of our study is to synthesize and evaluate the toxicity of silica nanoparticles at various concentrations using chick embryo, as it serves as a bridging model between in vivo and ex vivo studies. Silica nanoparticles of 70 nm sizewith concentrations of 10, 20, 40 and 80 PPM were injected in vivo and incubated for 19 days as per IACUC guidelines. The study was carried out on dissected chick embryo after the 19th day of incubation. Vital tissues such as liver and heart tissues were subjected to toxicity assays. Biochemical assay of antioxidant enzymes like superoxide dismutase and glutathione peroxide were assessed. The results showed a decreased level of MDA (Malondialdehyde, an end product of lipid Peroxidation, whereas increased activity of superoxide dismutase and glutathione peroxide were observed. Therefore silica nanoparticles may be used as a pesticide and also as a biomaterial for therapeutic application in the field of medicine.

  10. Involvement of Notch signaling in early chick ovarian follicle development.

    Science.gov (United States)

    Li, Jun; Zhao, Dan; Guo, Changquan; Li, Jian; Mi, Yuling; Zhang, Caiqiao

    2016-01-01

    The formation of primordial follicles is a crucial process in the establishment of follicle pools required for the female's reproductive life span. For laying hens, ample follicles are a prerequisite for high laying performance. Notch signaling plays critical roles in germ cell cysts breakdown and in the formation of primordial follicles. Here, we investigated the role of Notch signaling in the ovarian development of post-hatch chicks. Results showed that around post-hatch day 4 (H4), the germ cell cysts broke apart, oocytes became surrounded by squamous pregranulosa cells, and the primordial follicles were then formed. Subsequently, we detected the expression of Notch signaling-related genes including Notch receptors (Notch1, 2), ligands (Jag1, 2 and Dll1, 4), and target genes (Hes1, Hey1). These genes all showed expression at H4 and some of these genes were up-regulated during primordial follicle formation. To evaluate the Notch signaling requirement for early follicular development, we adopted an in vitro ovary culture system. Suppression of Notch signaling by γ-secretase inhibitor induced a decrease of primordial follicles and an increase of germ cells in cysts. Attenuating Notch signaling also inhibited the phosphatidylinositol 3-kinase/protein kinase B pathways and suppressed cadherin expression. These results suggest that Notch signaling is endowed with an indispensable role in primordial follicle formation in post-hatch chicks.

  11. CME on March 16, 2001, electron pulsation event and solar-terrestrial phenomena related with CMEs

    Institute of Scientific and Technical Information of China (English)

    张桂清

    2002-01-01

    The electron pulsation event is defined in the paper. Firstly, a slow Halo CME on March 16, 2001 that led to low-energetic solar proton event, electron pulsation event and major geomagnetic storm was analyzed. And then, dozens of events are collected. The interrelations among the solar flare, CME, solar proton event, electron pulsation event and geomagnetic storm are studied. The results show that: (ⅰ) Solar proton events can be regarded as the indication that CMEs get to the earth and the electron pulsation events can be regarded as the indication of solar proton flux. (ⅱ) Not only can fast CMEs strongly influence the earth, but also slow CMEs can influence the earth, and its influences are more frequent and cannot be neglected. (ⅲ) Most of high-energetic solar proton events with E≥10 MeV can lead to geomagnetic storms, but most of the medium and weak geomagnetic storms result from low-energetic solar proton events that are caused by CMEs. (ⅳ) Both the electron pulsation events and geomagnetic storms are the link effects of high- and low-energetic solar proton events, but the occurrence of electron pulsation event are generally prior to the geomagnetic storm. So in the circumstance where the near real-time observing data of the low-energetic solar proton event cannot be obtained, we can regard electron pulsation event as the indication of the low-energetic solar proton flux reaching the earth, which can be used as one of the important 参考文献 of short-term prediction and alert of the geomagnetic storm.

  12. CME on March 16, 2001, electron pulsation event and solar-terrestrial phenomena related with CMEs

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Guiqing(张桂清)

    2002-01-01

    The electron pulsation event is defined in the paper. Firstly, a slow Halo CME on March 16, 2001 that led to low-energetic solar proton event, electron pulsation event and major geomagnetic storm was analyzed. And then, dozens of events are collected. The interrelations among the solar flare, CME, solar proton event, electron pulsation event and geomagnetic storm are studied. The results show that: (ⅰ) Solar proton events can be regarded as the indication that CMEs get to the earth and the electron pulsation events can be regarded as the indication of solar proton flux. (ⅱ) Not only can fast CMEs strongly influence the earth, but also slow CMEs can influence the earth, and its influences are more frequent and cannot be neglected. (ⅲ) Most of high-energetic solar proton events with E≥10 MeV can lead to geomagnetic storms, but most of the medium and weak geomagnetic storms result from low-energetic solar proton events that are caused by CMEs. (ⅳ) Both the electron pulsation events and geomagnetic storms are the link effects of high- and low-energetic solar proton events, but the occurrence of electron pulsation event are generally prior to the geomagnetic storm. So in the circumstance where the near real-time observing data of the low-energetic solar proton event cannot be obtained, we can regard electron pulsation event as the indication of the low-energetic solar proton flux reaching the earth, which can be used as one of the important 参考文献 of short-term prediction and alert of the geomagnetic storm.

  13. CoRoT's view of newly discovered B-star pulsators: results for 358 candidate B pulsators from the initial run's exoplanet field data

    Science.gov (United States)

    Degroote, P.; Aerts, C.; Ollivier, M.; Miglio, A.; Debosscher, J.; Cuypers, J.; Briquet, M.; Montalbán, J.; Thoul, A.; Noels, A.; De Cat, P.; Balaguer-Núñez, L.; Maceroni, C.; Ribas, I.; Auvergne, M.; Baglin, A.; Deleuil, M.; Weiss, W. W.; Jorda, L.; Baudin, F.; Samadi, R.

    2009-10-01

    Context: We search for new variable B-type pulsators in the CoRoT data assembled primarily for planet detection, as part of CoRoT's additional programme. Aims: We aim to explore the properties of newly discovered B-type pulsators from the uninterrupted CoRoT space-based photometry and to compare them with known members of the β Cep and slowly pulsating B star (SPB) classes. Methods: We developed automated data analysis tools that include algorithms for jump correction, light-curve detrending, frequency detection, frequency combination search, and for frequency and period spacing searches. Results: Besides numerous new, classical, slowly pulsating B stars, we find evidence for a new class of low-amplitude B-type pulsators between the SPB and δ Sct instability strips, with a very broad range of frequencies and low amplitudes, as well as several slowly pulsating B stars with residual excess power at frequencies typically a factor three above their expected g-mode frequencies. Conclusions: The frequency data we obtained for numerous new B-type pulsators represent an appropriate starting point for further theoretical analyses of these stars, once their effective temperature, gravity, rotation velocity, and abundances will be derived spectroscopically in the framework of an ongoing FLAMES survey at the VLT. The CoRoT space mission was developed and is operated by the French space agency CNES, with the participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain. All frequency tables, including the identification of combination frequencies, are only available as online material. Frequency Tables are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/506/471 Bâtiment 121, 91405, Orsay Cedex, France. Postdoctoral Researcher, Fonds de la Recherche Scientifique - FNRS, Belgium. Postdoctoral Fellow of the Fund for Scientific Research

  14. Myostatin promotes the terminal differentiation of embryonic muscle progenitors

    OpenAIRE

    Manceau, Marie; Gros, Jérôme; Savage, Kathleen; Thomé, Virginie; McPherron, Alexandra; Paterson, Bruce; Marcelle, Christophe

    2008-01-01

    Myostatin, a TGF-β family member, is an important regulator of adult muscle size. While extensively studied in vitro, the mechanisms by which this molecule mediates its effect in vivo are poorly understood. We addressed this question using chick and mouse embryos. We show that while myostatin overexpression in chick leads to an exhaustion of the muscle progenitor population that ultimately results in muscle hypotrophy, myostatin loss of function in chick and mouse provokes an expansion of thi...

  15. Epigenetic influence on embryonic development

    DEFF Research Database (Denmark)

    Donkin, Ida; Barrès, Romain; Pinborg, Anja

    2016-01-01

    The epigenome is sensitive to environmental changes and can sustainably alter gene expression, notably during embryonic development. New research indicates that epigenetic factors are heritable, which is why paternal lifestyle may affect fetal development and risk of disease. Children conceived...... by assisted reproduction technology (ART) have an increased risk of peri- and postnatal complications, and as specific ART protocols associate with specific risk profiles, the procedures themselves may cause epigenetic changes contributing to the altered outcomes of the 5,000 Danish children annually...

  16. Possible link of sudden onset and short-time periodic pulsation of polar mesosphere summer echoes to ULF Pc5 geomagnetic pulsations and solar wind dynamic pressure enhancement

    Science.gov (United States)

    Lee, Y.; Kirkwood, S.; Kwak, Y. S.

    2016-12-01

    The EISCAT VHF incoherent scatter radar in Tromsö, Norway, makes occasional observations of electron densities and Polar Mesosphere Summer Echoes, in the summer polar D-region ionosphere. In one of those datasets, pulsating polar mesospheric summer echoes (PMSE) are observed, with periodicities in the ultra-low frequency (ULF) Pc5 band (1.6-6.7 mHz), following an abrupt increase of the radar reflectivity when a geomagnetic field excursion is started, in turn linked to dynamic pressure (Pdyn) enhancement in the solar wind. At the excursion of the magnetic field, at auroral altitudes of 90 km and above, electron density is abruptly enhanced, followed by a series of short-lived peaks, superimposed on an enhanced level. The short-lived peaks are likely a signature of transient Pc5 geomagnetic pulsations and associated energetic electron precipitation from pitch-angle scattering into the loss cone in the magnetosphere. At the same time, at altitudes around 80-90 km, a sharp increase of PMSE reflectivity occurs, 100 times greater than the increase of electron density, and is followed by pulsating PMSE reflectivity with periodicities in the Pc5 band, increasing and decreasing in magnitude during the course of the next hour. The increase of the pulsation magnitude may be attributed to an increase of high-energy electron precipitation flux ( >30 keV) penetrating to at least the height of maximum PMSE reflectivity. This study suggests that Pc5 pulsation bursts in both magnetic field and high energy electron precipitation could play a crucial role in producing PMSE fluctuations on minute-to-minute time scales.

  17. Increased mortality of black-browed albatross chicks at a colony heavily-infested with the tick Ixodes uriae.

    Science.gov (United States)

    Bergström, S; Haemig, P D; Olsen, B

    1999-09-01

    At Bird Island, South Georgia, we studied the effects of the tick Ixodes uriae on survival of chicks at two colonies of the black-browed albatross Diomedea melanophrys, one where most chicks were infested with ticks, the other where most chicks were tick-free. When the two colonies were compared, it was found that the colony heavily-infested with ticks had significantly greater chick mortality than the colony lightly-infested with ticks. However, within each of the two colonies, there was no significant difference in survival between chicks with ticks and those without ticks.

  18. Development of the chick pancreas with regard to estimation of the relative occurrence and growth of endocrine tissue.

    Science.gov (United States)

    Manáková, E; Titlbach, M

    2007-04-01

    Endocrine cells in chick pancreas were observed to map their distribution during development and to perform morphometric studies starting on embryonic day 5. The ratio of exocrine to endocrine tissues first prevailed in favour of the endocrine ones, and changed abruptly after day 9 when rapid growth of exocrine tissue began. Endocrine tissue was formed of two types of islets. The 'light' (or B) islets were composed of insulin-immunoreactive cells, completed perhaps by a few somatostatin-immunoreactive cells occurring on the periphery. The majority of the somatostatin- and glucagon-immunoreactive cells were present in the 'dark' (or A) islets. Endocrine elements were also scattered as single cells over the pancreas. Sporadically, the endocrine cells established contacts with exocrine ducts. In morphometric analysis, volume density of insulin-, glucagon-, and somatostatin-immunoreactive cells was measured, and ratios were calculated between particular components. The volume density of endocrine cells and their ratio appeared stable in individual lobes but varied significantly between each other. Increase of the glucagon volume density is exponential, whereas insulin increases almost linearly especially in splenic lobe. The process results in the increase of the hormone-immunoreactive cell volume density in favour of glucagon-immunoreactive cells typical for birds.

  19. Toxicity and 7-ethoxyresorufin O-deethylase-inducing potency of coplanar polychlorinated biphenyls (PCBs) in chick embryos

    Energy Technology Data Exchange (ETDEWEB)

    Brunstroem, B.; Andersson, L.

    1988-10-01

    The toxicities of the coplanar polychlorinated biphenyls 3,3',4,4'-tetrachlorobiphenyl (TCB), 3,3',4,4',5-pentachlorobiphenyl (PeCB) and 3,3',4,4',5,5'-hexachlorobiphenyl (HCB) were compared in a 72-h study on chick embryos. The substances were injectied into the air sacs of hens's eggs preincubated for 7 days. Mortality was measured 72 h later and corresponding LD/sub 50/ values were calculated. The rank order of toxicity was PeCB>TCB>HCB. Using the same injection procedure, the potencies of these chlorobiphenyls with regard to their induction of hepatic 7-ethoxyresorufin O-deethylase activity were compared. The ranking order of the substances as inducers was the same as their order when ranked according to toxicity. The three coplanar chlorobiphenyls were considerably more toxic and potent as inducers than the non-planar 2,2',4,4',5,5'-hexachlorobiphenyl. In a 2-week toxicity study, PeCB and HCB were injected into the yolks of hens' eggs preincubated for 4 days. PeCB was about 50-fold more potent than HCB in causing embryonic death. Both substances caused abnormalities, including edema, liver lesions, microphthalmia and beak deformities.

  20. Embryonic anti-aging niche.

    Science.gov (United States)

    Conboy, Irina M; Yousef, Hanadie; Conboy, Michael J

    2011-05-01

    Although functional organ stem cells persist in the old, tissue damage invariably overwhelms tissue repair, ultimately causing the demise of an organism. The poor performance of stem cells in an aged organ, such as skeletal muscle, is caused by the changes in regulatory pathways such as Notch, MAPK and TGF-β, where old differentiated tissue actually inhibits its own regeneration. This perspective analyzes the current literature on regulation of organ stem cells by their young versus old niches and suggests that determinants of healthy and prolonged life might be under a combinatorial control of cell cycle check point proteins and mitogens, which need to be tightly balanced in order to promote tissue regeneration without tumor formation. While responses of adult stem cells are regulated extrinsically and age-specifically, we put forward experimental evidence suggesting that embryonic cells have an intrinsic youthful barrier to aging and produce soluble pro-regenerative proteins that signal the MAPK pathway for rejuvenating myogenesis. Future identification of this activity will improve our understanding of embryonic versus adult regulation of tissue regeneration suggesting novel strategies for organ rejuvenation. Comprehensively, the current intersection of aging and stem cell science indicates that if the age-imposed decline in the regenerative capacity of stem cells was understood, the debilitating lack of organ maintenance in the old could be ameliorated and perhaps, even reversed.