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Sample records for factor 3f oscillates

  1. Expression of human eukaryotic initiation factor 3f oscillates with cell cycle in A549 cells and is essential for cell viability

    PubMed Central

    2010-01-01

    Background Transcriptional and postranslational regulation of the cell cycle has been widely studied. However, there is scarce knowledge concerning translational control of this process. Several mammalian eukaryotic initiation factors (eIFs) seem to be implicated in controlling cell proliferation. In this work, we investigated if the human eIF3f expression and function is cell cycle related. Results The human eIF3f expression has been found to be upregulated in growth-stimulated A549 cells and downregulated in G0. Western blot analysis and eIF3f promotor-luciferase fusions revealed that eIF3f expression peaks twice in the cell cycle: in the S and the M phases. Deregulation of eIF3f expression negatively affects cell viability and induces apoptosis. Conclusions The expression pattern of human eIF3f during the cell cycle confirms that this gene is cell division related. The fact that eIF3f expression peaks in two cell cycle phases raises the possibility that this gene may exert a differential function in the S and M phases. Our results strongly suggest that eIF3f is essential for cell proliferation. PMID:20462454

  2. The factor XIIa blocking antibody 3F7: a safe anticoagulant with anti-inflammatory activities.

    PubMed

    Worm, Marie; Köhler, Elodie C; Panda, Rachita; Long, Andy; Butler, Lynn M; Stavrou, Evi X; Nickel, Katrin F; Fuchs, Tobias A; Renné, Thomas

    2015-10-01

    The plasma protein factor XII (FXII) is the initiating protease of the procoagulant and proinflammatory contact system. FXII activates both the bradykinin (BK) producing kallikrein-kinin system and the intrinsic pathway of coagulation. Contact with negatively charged surfaces induces auto-activation of zymogen FXII that results in activated FXII (FXIIa). Various in vivo activators of FXII have been identified including heparin, misfolded protein aggregates, nucleic acids and polyphosphate. Murine models have established a central role of FXII in arterial and venous thromboembolic diseases. Despite the central function of FXII in pathologic thrombosis, its deficiency does not impair hemostasis in animals or humans. The selective role of FXIIa in thrombosis, but not hemostasis, offers an exciting novel strategy for safe anticoagulation based on interference with FXIIa. We have generated the recombinant fully human FXIIa-blocking antibody 3F7, which abolished FXIIa enzymatic activity and prevented thrombosis in a cardiopulmonary bypass system in large animals, in the absence of increased therapy-associated bleeding. Furthermore, 3F7 also interfered with BK-driven edema in the severe swelling disorder hereditary angioedema (HAE) type III. Taken together, targeting FXIIa with 3F7 appears to be a promising approach to treat edema disorders and thrombosis. PMID:26605293

  3. The factor XIIa blocking antibody 3F7: a safe anticoagulant with anti-inflammatory activities

    PubMed Central

    Worm, Marie; Köhler, Elodie C.; Panda, Rachita; Long, Andy; Butler, Lynn M.; Stavrou, Evi X.; Nickel, Katrin F.; Fuchs, Tobias A.

    2015-01-01

    The plasma protein factor XII (FXII) is the initiating protease of the procoagulant and proinflammatory contact system. FXII activates both the bradykinin (BK) producing kallikrein-kinin system and the intrinsic pathway of coagulation. Contact with negatively charged surfaces induces auto-activation of zymogen FXII that results in activated FXII (FXIIa). Various in vivo activators of FXII have been identified including heparin, misfolded protein aggregates, nucleic acids and polyphosphate. Murine models have established a central role of FXII in arterial and venous thromboembolic diseases. Despite the central function of FXII in pathologic thrombosis, its deficiency does not impair hemostasis in animals or humans. The selective role of FXIIa in thrombosis, but not hemostasis, offers an exciting novel strategy for safe anticoagulation based on interference with FXIIa. We have generated the recombinant fully human FXIIa-blocking antibody 3F7, which abolished FXIIa enzymatic activity and prevented thrombosis in a cardiopulmonary bypass system in large animals, in the absence of increased therapy-associated bleeding. Furthermore, 3F7 also interfered with BK-driven edema in the severe swelling disorder hereditary angioedema (HAE) type III. Taken together, targeting FXIIa with 3F7 appears to be a promising approach to treat edema disorders and thrombosis. PMID:26605293

  4. The Rice Eukaryotic Translation Initiation Factor 3 Subunit f (OseIF3f) Is Involved in Microgametogenesis

    PubMed Central

    Li, Qi; Deng, Zhuyun; Gong, Chunyan; Wang, Tai

    2016-01-01

    Microgametogenesis is the post-meiotic pollen developmental phase when unicellular microspores develop into mature tricellular pollen. In rice, microgametogenesis can influence grain yields to a great degree because pollen abortion occurs more easily during microgametogenesis than during other stages of pollen development. However, our knowledge of the genes involved in microgametogenesis in rice remains limited. Due to the dependence of pollen development on the regulatory mechanisms of protein expression, we identified the encoding gene of the eukaryotic translation initiation factor 3, subunit f in Oryza sativa (OseIF3f). Immunoprecipitation combined with mass spectrometry confirmed that OseIF3f was a subunit of rice eIF3, which consisted of at least 12 subunits including eIF3a, eIF3b, eIF3c, eIF3d, eIF3e, eIF3f, eIF3g, eIF3h, eIF3i, eIF3k, eIF3l, and eIF3m. OseIF3f showed high mRNA levels in immature florets and is highly abundant in developing anthers. Subcellular localization analysis showed that OseIF3f was localized to the cytosol and the endoplasmic reticulum in rice root cells. We further analyzed the biological function of OseIF3f using the double-stranded RNA-mediated interference (RNAi) approach. The OseIF3f-RNAi lines grew normally at the vegetative stage but displayed a large reduction in seed production and pollen viability, which is associated with the down-regulation of OseIF3f. Further cytological observations of pollen development revealed that the OseIF3f-RNAi lines showed no obvious abnormalities at the male meiotic stage and the unicellular microspore stage. However, compared to the wild-type, OseIF3f-RNAi lines contained a higher percentage of arrested unicellular pollen at the bicellular stage and a higher percentage of arrested unicellular and bicellular pollen, and aborted pollen at the tricellular stage. These results indicate that OseIF3f plays a role in microgametogenesis. PMID:27200010

  5. Tumultuous Relationship between the Human Immunodeficiency Virus Type 1 Viral Infectivity Factor (Vif) and the Human APOBEC-3G and APOBEC-3F Restriction Factors

    PubMed Central

    Henriet, Simon; Mercenne, Gaëlle; Bernacchi, Serena; Paillart, Jean-Christophe; Marquet, Roland

    2009-01-01

    Summary: The viral infectivity factor (Vif) is dispensable for human immunodeficiency virus type 1 (HIV-1) replication in so-called permissive cells but is required for replication in nonpermissive cell lines and for pathogenesis. Virions produced in the absence of Vif have an aberrant morphology and an unstable core and are unable to complete reverse transcription. Recent studies demonstrated that human APOBEC-3G (hA3G) and APOBEC-3F (hA3F), which are selectively expressed in nonpermissive cells, possess strong anti-HIV-1 activity and are sufficient to confer a nonpermissive phenotype. Vif induces the degradation of hA3G and hA3F, suggesting that its main function is to counteract these cellular factors. Most studies focused on the hypermutation induced by the cytidine deaminase activity of hA3G and hA3F and on their Vif-induced degradation by the proteasome. However, recent studies suggested that several mechanisms are involved both in the antiviral activity of hA3G and hA3F and in the way Vif counteracts these antiviral factors. Attempts to reconcile the studies involving Vif in virus assembly and stability with these recent findings suggest that hA3G and hA3F partially exert their antiviral activity independently of their catalytic activity by destabilizing the viral core and the reverse transcription complex, possibly by interfering with the assembly and/or maturation of the viral particles. Vif could then counteract hA3G and hA3F by excluding them from the viral assembly intermediates through competition for the viral genomic RNA, by regulating the proteolytic processing of Pr55Gag, by enhancing the efficiency of the reverse transcription process, and by inhibiting the enzymatic activities of hA3G and hA3F. PMID:19487726

  6. Tumultuous relationship between the human immunodeficiency virus type 1 viral infectivity factor (Vif) and the human APOBEC-3G and APOBEC-3F restriction factors.

    PubMed

    Henriet, Simon; Mercenne, Gaëlle; Bernacchi, Serena; Paillart, Jean-Christophe; Marquet, Roland

    2009-06-01

    The viral infectivity factor (Vif) is dispensable for human immunodeficiency virus type 1 (HIV-1) replication in so-called permissive cells but is required for replication in nonpermissive cell lines and for pathogenesis. Virions produced in the absence of Vif have an aberrant morphology and an unstable core and are unable to complete reverse transcription. Recent studies demonstrated that human APOBEC-3G (hA3G) and APOBEC-3F (hA3F), which are selectively expressed in nonpermissive cells, possess strong anti-HIV-1 activity and are sufficient to confer a nonpermissive phenotype. Vif induces the degradation of hA3G and hA3F, suggesting that its main function is to counteract these cellular factors. Most studies focused on the hypermutation induced by the cytidine deaminase activity of hA3G and hA3F and on their Vif-induced degradation by the proteasome. However, recent studies suggested that several mechanisms are involved both in the antiviral activity of hA3G and hA3F and in the way Vif counteracts these antiviral factors. Attempts to reconcile the studies involving Vif in virus assembly and stability with these recent findings suggest that hA3G and hA3F partially exert their antiviral activity independently of their catalytic activity by destabilizing the viral core and the reverse transcription complex, possibly by interfering with the assembly and/or maturation of the viral particles. Vif could then counteract hA3G and hA3F by excluding them from the viral assembly intermediates through competition for the viral genomic RNA, by regulating the proteolytic processing of Pr55(Gag), by enhancing the efficiency of the reverse transcription process, and by inhibiting the enzymatic activities of hA3G and hA3F. PMID:19487726

  7. Factorization method for the truncated harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Fernández C, D. J.; Morales-Salgado, V. S.

    2015-04-01

    Factorization procedures of first and second order are used to generate Hamiltonians with known spectra departing from the harmonic oscillator with an infinite potential barrier. Certain systems obtained in a straightforward way through said method possess differential ladder operators of both types, third and fourth order. Since systems with this kind of operators are linked with the Painlevé IV and V equations respectively, several solutions of these non-linear second-order differential equations will be simply found.

  8. Missense Mutation of POU Domain Class 3 Transcription Factor 3 in Pou3f3L423P Mice Causes Reduced Nephron Number and Impaired Development of the Thick Ascending Limb of the Loop of Henle.

    PubMed

    Rieger, Alexandra; Kemter, Elisabeth; Kumar, Sudhir; Popper, Bastian; Aigner, Bernhard; Wolf, Eckhard; Wanke, Rüdiger; Blutke, Andreas

    2016-01-01

    During nephrogenesis, POU domain class 3 transcription factor 3 (POU3F3 aka BRN1) is critically involved in development of distinct nephron segments, including the thick ascending limb of the loop of Henle (TAL). Deficiency of POU3F3 in knock-out mice leads to underdevelopment of the TAL, lack of differentiation of TAL cells, and perinatal death due to renal failure. Pou3f3L423P mutant mice, which were established in the Munich ENU Mouse Mutagenesis Project, carry a recessive point mutation in the homeobox domain of POU3F3. Homozygous Pou3f3L423P mutants are viable and fertile. The present study used functional, as well as qualitative and quantitative morphological analyses to characterize the renal phenotype of juvenile (12 days) and aged (60 weeks) homo- and heterozygous Pou3f3L423P mutant mice and age-matched wild-type controls. In both age groups, homozygous mutants vs. control mice displayed significantly smaller kidney volumes, decreased nephron numbers and mean glomerular volumes, smaller TAL volumes, as well as lower volume densities of the TAL in the kidney. No histological or ultrastructural lesions of TAL cells or glomerular cells were observed in homozygous mutant mice. Aged homozygous mutants displayed increased serum urea concentrations and reduced specific urine gravity, but no evidence of glomerular dysfunction. These results confirm the role of POU3F3 in development and function of the TAL and provide new evidence for its involvement in regulation of the nephron number in the kidney. Therefore, Pou3f3L423P mutant mice represent a valuable research model for further analyses of POU3F3 functions, or for nephrological studies examining the role of congenital low nephron numbers. PMID:27420727

  9. Missense Mutation of POU Domain Class 3 Transcription Factor 3 in Pou3f3L423P Mice Causes Reduced Nephron Number and Impaired Development of the Thick Ascending Limb of the Loop of Henle

    PubMed Central

    Rieger, Alexandra; Kemter, Elisabeth; Kumar, Sudhir; Popper, Bastian; Aigner, Bernhard; Wolf, Eckhard; Wanke, Rüdiger; Blutke, Andreas

    2016-01-01

    During nephrogenesis, POU domain class 3 transcription factor 3 (POU3F3 aka BRN1) is critically involved in development of distinct nephron segments, including the thick ascending limb of the loop of Henle (TAL). Deficiency of POU3F3 in knock-out mice leads to underdevelopment of the TAL, lack of differentiation of TAL cells, and perinatal death due to renal failure. Pou3f3L423P mutant mice, which were established in the Munich ENU Mouse Mutagenesis Project, carry a recessive point mutation in the homeobox domain of POU3F3. Homozygous Pou3f3L423P mutants are viable and fertile. The present study used functional, as well as qualitative and quantitative morphological analyses to characterize the renal phenotype of juvenile (12 days) and aged (60 weeks) homo- and heterozygous Pou3f3L423P mutant mice and age-matched wild-type controls. In both age groups, homozygous mutants vs. control mice displayed significantly smaller kidney volumes, decreased nephron numbers and mean glomerular volumes, smaller TAL volumes, as well as lower volume densities of the TAL in the kidney. No histological or ultrastructural lesions of TAL cells or glomerular cells were observed in homozygous mutant mice. Aged homozygous mutants displayed increased serum urea concentrations and reduced specific urine gravity, but no evidence of glomerular dysfunction. These results confirm the role of POU3F3 in development and function of the TAL and provide new evidence for its involvement in regulation of the nephron number in the kidney. Therefore, Pou3f3L423P mutant mice represent a valuable research model for further analyses of POU3F3 functions, or for nephrological studies examining the role of congenital low nephron numbers. PMID:27420727

  10. Key role for myeloid cells: phase II results of anti-G(D2) antibody 3F8 plus granulocyte-macrophage colony-stimulating factor for chemoresistant osteomedullary neuroblastoma.

    PubMed

    Cheung, Nai-Kong V; Cheung, Irene Y; Kramer, Kim; Modak, Shakeel; Kuk, Deborah; Pandit-Taskar, Neeta; Chamberlain, Elizabeth; Ostrovnaya, Irina; Kushner, Brian H

    2014-11-01

    Anti-G(D2) murine antibody 3F8 plus subcutaneously (sc) administered granulocyte-macrophage colony-stimulating factor (GM-CSF) was used against primary refractory neuroblastoma in metastatic osteomedullary sites. Large study size and long follow-up allowed assessment of prognostic factors in a multivariate analysis not reported with other anti-G(D2) antibodies. In a phase II trial, 79 patients without prior progressive disease were treated for persistent osteomedullary neuroblastoma documented by histology and/or metaiodobenzyl-guanidine (MIBG) scan. In the absence of human antimouse antibody, 3F8 + scGM-CSF cycles were repeated up to 24 months. Minimal residual disease (MRD) in bone marrow was measured by quantitative reverse transcription-polymerase chain reaction pre-enrollment and post-cycle #2, before initiation of 13-cis-retinoic acid. Study endpoints were: (i) progression-free survival (PFS) compared with the predecessor trial of 3F8 plus intravenously administered (iv) GM-CSF (26 patients) and (ii) impact of MRD on PFS. Using all 105 patients from the two consecutive 3F8 + GM-CSF trials, prognostic factors were analyzed by multivariate Cox regression model. Complete response rates to 3F8 + scGM-CSF were 87% by histology and 38% by MIBG. Five-year PFS was 24 ± 6%, which was significantly superior to 11 ± 7% with 3F8 + ivGM-CSF (p = 0.002). In the multivariate analysis, significantly better PFS was associated with R/R or H/R FCGR2A polymorphism, sc route of GM-CSF and early MRD response. MYCN amplification was not prognostic. Complement consumption was similar with either route of GM-CSF. Toxicities were manageable, allowing outpatient treatment. 3F8 + scGM-CSF is highly active against chemoresistant osteomedullary neuroblastoma. MRD response may be an indicator of tumor sensitivity to anti-G(D2) immunotherapy. Correlative studies highlight the antineoplastic potency of myeloid effectors. PMID:24644014

  11. Dynamical structure factor of magnetic Bloch oscillations at finite temperatures

    NASA Astrophysics Data System (ADS)

    Syljuåsen, Olav F.

    2015-10-01

    Domain-walls in one-dimensional Ising ferromagnets can undergo Bloch oscillations when subjected to a skew magnetic field. Such oscillations imply finite temperature non-dispersive low-frequency peaks in the dynamical structure factor which can be probed in neutron scattering. We study in detail the spectral weight of these peaks. Using an analytical approach based on an approximate treatment of a gas of spin-cluster excitations we give an explicit expression for the momentum- and temperature-dependence of the spectral weights. Generally the spectral weights increase with temperature T and approaches the same order of magnitude as the spin-wave spectral weights at high temperatures. We compare the analytical expression to numerical exact diagonalizations and find that it can, without any adjustable parameters, account for the T and momentum-transfer dependence of the numerically obtained spectral weights in the parameter regime where the ratio of magnetic fields h x / h z ≪ 1 and the temperature is h x < T < ˜ J z /2. We also carry out numerical calculations pertinent to the material CoNb2O6, and find qualitatively similar results.

  12. Murine Anti-GD2 Monoclonal Antibody 3F8 Combined With Granulocyte-Macrophage Colony-Stimulating Factor and 13-Cis-Retinoic Acid in High-Risk Patients With Stage 4 Neuroblastoma in First Remission

    PubMed Central

    Cheung, Nai-Kong V.; Cheung, Irene Y.; Kushner, Brian H.; Ostrovnaya, Irina; Chamberlain, Elizabeth; Kramer, Kim; Modak, Shakeel

    2012-01-01

    Purpose Anti-GD2 monoclonal antibody (MoAb) combined with granulocyte-macrophage colony-stimulating factor (GM-CSF) has shown efficacy against neuroblastoma (NB). Prognostic variables that could influence clinical outcome were explored. Patients and Methods One hundred sixty-nine children diagnosed with stage 4 NB (1988 to 2008) were enrolled onto consecutive anti-GD2 murine MoAb 3F8 ± GM-CSF ± 13-cis-retinoic acid (CRA) protocols after achieving first remission (complete remission/very good partial remission). Patients enrolled in regimen A (n = 43 high-risk [HR] patients) received 3F8 alone; regimen B (n = 41 HR patients), 3F8 + intravenous GM-CSF + CRA, after stem-cell transplantation (SCT); and regimen C (n = 85), 3F8 + subcutaneous GM-CSF + CRA, 46 of 85 after SCT, whereas 28 of 85 required additional induction therapy and were deemed ultra high risk (UHR). Marrow minimal residual disease (MRD) was measured by quantitative reverse transcription polymerase chain reaction. Survival probability was calculated by the Kaplan-Meier method, and prognostic variables were analyzed by multivariate Cox regression model. Results At 5 years from the start of immunotherapy, progression-free survival (PFS) improved from 44% for HR patients receiving regimen A to 56% and 62% for those receiving regimens B and C, respectively. Overall survival (OS) was 49%, 61%, and 81%, respectively. PFS and OS of UHR patients were 36% and 75%, respectively. Relapse was mostly at isolated sites. Independent adverse prognostic factors included UHR (PFS) and post–cycle two MRD (PFS and OS), whereas the prognostic factors for improved outcome were missing killer immunoglobulin-like receptor ligand (PFS and OS), human antimouse antibody response (OS), and regimen C (OS). Conclusion Retrospective analysis of consecutive trials from a single center demonstrated that MoAb 3F8 + GM-CSF + CRA is effective against chemotherapy-resistant marrow MRD. Its positive impact on long-term survival can only

  13. Dichloroacetate toxicokinetics and disruption of tyrosine catabolism in B6C3F1 mice: dose-response relationships and age as a modifying factor

    SciTech Connect

    Schultz, Irv R. ); Merdink, James L.; Gonzalez-Leon, Alberto; Bull, R J.

    2002-01-01

    Dichloroacetate (DCA) is a well established rodent carcinogen commonly found in municipal drinking water supplies. Previous toxicokinetic studies have established that elimination of DCA is controlled by liver metabolism. DCA metabolism occurs by the cytosolic enzyme glutathione-S-transferase-zeta (GSTz). An important feature of the GSTz pathway is the autoinhibition of metabolism due to suicide inactivation of GSTz by DCA resulting in a direct reduction in GSTz activity. GSTz is identical to a key tyrosine catabolism enzyme known as maleylacetoacetate isomerase (MAAI; EC 5.3.1.2). In the tyrosine metabolism pathway, GSTz plays a critical role in catalyzing the isomerization of maleylacetoacetate to fumarylacetoacetate. Disruption of tyrosine catabolism has been linked to increased cancer risk in humans. We studied the elimination of i.v. doses of DCA to juvenile (8 week) and senescent (60 week) mice previously treated with DCA in their drinking water for 2 or 54 weeks. The diurnal change in blood concentrations of DCA was also monitored in mice exposed to three different drinking water concentrations of DCA (2.0, 0.5 and 0.05 g/L). Additional experiments measured the in-vitro metabolism of DCA in liver homogenates prepared from treated mice given various recovery times following treatment. The MAAI activity was also measured in liver cytosol obtained from treated mice. Results indicate juvenile mice were the most sensitive to changes in DCA elimination after drinking water treatment. MAAI activity was reduced up to 80% in liver cytosol from treated mice. These results indicate that inactivation and re-synthesis of GSTz is a highly dynamic process and is supportive of the hypothesis that decreased MAAI activity is a contributing factor in the carcinogenesis of DCA.

  14. Franck-Condon factors for multidimensional harmonic oscillators

    NASA Astrophysics Data System (ADS)

    Malmqvist, Per-Åke; Forsberg, Niclas

    1998-03-01

    We present a simple formula for the overlap integrals of two sets of multi-dimensional harmonic oscillators. The oscillators have in general different equilibrium points, force constants, and natural vibration modes. The formula expresses the overlap matrix in the one-dimensional case, < m'| n''>, as a so-called LU decomposition, =<0'|0''> limit∑L mtU tn, where the summation index has a range 0≤ t≤min( m, n), i.e., it is the matrix product of a lower-triangular matrix L with an upper-triangular U. These matrices are obtained from simple recursion formulae. This form is essentially retained in the multi-dimensional case. General matrix elements are obtained by exact and finite expressions, relating them to matrix elements over a single set of harmonic oscillator wave functions. We present test calculations with error estimates, also comparing with literature examples.

  15. The in vitro Biochemical Characterization of an HIV-1 Restriction Factor APOBEC3F: Importance of Loop 7 on Both CD1 and CD2 for DNA Binding and Deamination.

    PubMed

    Chen, Qihan; Xiao, Xiao; Wolfe, Aaron; Chen, Xiaojiang S

    2016-07-01

    APOBEC3F (A3F) is a member of the apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) family of proteins that can deaminate cytosine (C) to uracil (U) on nucleic acids. A3F is one of the four APOBEC members with two Zn-coordinated homologous cytosine deaminase (CD) domains, with the others being A3G, A3D, and A3B. Here we report the in vitro characterization of DNA binding and deaminase activities using purified wild-type and various mutant proteins of A3F from an Escherichia coli expression system. We show that even though CD1 is catalytically inactive and CD2 is the active deaminase domain, presence of CD1 on the N-terminus of CD2 enhances the deaminase activity by over an order of magnitude. This enhancement of CD2 catalytic activity is mainly through the increase of substrate single-stranded (ss) DNA binding by the N-terminal CD1 domain. We further show that the loop 7 of both CD1 and CD2 of A3F plays an important role for ssDNA binding for each individual domain, as well as for the deaminase activity of CD2 domain in the full-length A3F. PMID:27063502

  16. Collisional narrowing by polyatomic buffer gases in an optically pumped CH3F laser

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.; Koepf, G. A.

    1980-01-01

    The gain linewidth of an optically pumped CH3F molecular laser is observed with the addition of various polyatomic buffer gases. This is interpreted as collisional (Dicke) narrowing. The measurement is the first observation of collisional narrowing by polyatomic buffer gases. It is also the first observation of the effect in a laser oscillator. The effect was observed using a heterodyne mixing technique at the laser emission frequency of 604 GHz. Collision cross sections for SF6-CH3F and CS2-CH3F are obtained.

  17. Frequency modulated translocational oscillations of Nrf2, a transcription factor functioning like a wireless sensor.

    PubMed

    Xue, Mingzhan; Momiji, Hiroshi; Rabbani, Naila; Bretschneider, Till; Rand, David A; Thornalley, Paul J

    2015-08-01

    The discovery that nuclear factor erythroid 2-related factor 2 (Nrf2) undergoes translocational oscillations from cytoplasm to nucleus in human cells with frequency modulation linked to activation of a stress-stimulated cytoprotective response raises the prospect that the Nrf2 works mechanistically analogous to a wireless sensor. Herein, we consider how this new model of Nrf2 oscillation resolves previous inexplicable experimental findings on Nrf2 regulation and why it is fit-for-purpose. Further investigation is required to assess how generally applicable the oscillatory mechanism is and if characteristics of this regulatory control can be found in vivo. It suggests there are multiple, potentially re-enforcing receptors for Nrf2 activation, indicating that potent Nrf2 activation for improved health and treatment of disease may be achieved through combination of Nrf2 system stimulants. PMID:26551710

  18. Noisy transcription factor NF-κB oscillations stabilize and sensitize cytokine signaling in space

    NASA Astrophysics Data System (ADS)

    Gangstad, Sirin W.; Feldager, Cilie W.; Juul, Jeppe; Trusina, Ala

    2013-02-01

    NF-κB is a major transcription factor mediating inflammatory response. In response to a pro-inflammatory stimulus, it exhibits a characteristic response—a pulse followed by noisy oscillations in concentrations of considerably smaller amplitude. NF-κB is an important mediator of cellular communication, as it is both activated by and upregulates production of cytokines, signals used by white blood cells to find the source of inflammation. While the oscillatory dynamics of NF-κB has been extensively investigated both experimentally and theoretically, the role of the noise and the lower secondary amplitude has not been addressed. We use a cellular automaton model to address these issues in the context of spatially distributed communicating cells. We find that noisy secondary oscillations stabilize concentric wave patterns, thus improving signal quality. Furthermore, both lower secondary amplitude as well as noise in the oscillation period might be working against chronic inflammation, the state of self-sustained and stimulus-independent excitations. Our findings suggest that the characteristic irregular secondary oscillations of lower amplitude are not accidental. On the contrary, they might have evolved to increase robustness of the inflammatory response and the system's ability to return to a pre-stimulated state.

  19. Ca(5)Zr(3)F(22).

    PubMed

    Oudahmane, Abdelghani; El-Ghozzi, Malika; Avignant, Daniel

    2012-04-01

    Single crystals of Ca(5)Zr(3)F(22), penta-calcium trizirconium docosafluoride, were obtained unexpectedly by solid-state reaction between CaF(2) and ZrF(4) in the presence of AgF. The structure of the title compound is isotypic with that of Sr(5)Zr(3)F(22) and can be described as being composed of layers with composition [Zr(3)F(20)](8-) made up from two different [ZrF(8)](4-) square anti-prisms (one with site symmetry 2) by corner-sharing. The layers extending parallel to the (001) plane are further linked by Ca(2+) cations, forming a three-dimensional network. Amongst the four crystallographically different Ca(2+) ions, three are located on twofold rotation axes. The Ca(2+) ions exhibit coordination numbers ranging from 8 to 12, depending on the cut off, with very distorted fluorine environments. Two of the Ca(2+) ions occupy inter-stices between the layers whereas the other two are located in void spaces of the [Zr(3)F(20)](8-) layer and alternate with the two Zr atoms along [010]. The crystal under investigation was an inversion twin. PMID:22589749

  20. Miniaturisation and high quality factor of spiral meander spurline resonator for microwave oscillator

    NASA Astrophysics Data System (ADS)

    Cho, Sung-Jin; Kim, Nam-Young

    2013-04-01

    The spiral meander spurline structure is an optimal solution for a reduced resonator size and a high Quality factor (Q-factor) compared to other conventional spurline structures. The spiral meander spurline resonator shows not only 38% reduced dimensional effect, but also 16% improved Q-factor compared with conventional meander spurline resonator. Moreover, in order to get more high quality factor, we analysed spurline slot width variation and designed the symmetric dual spiral meander structure, which has a 46.87% improved Q-factor compare with a single spiral meander. The symmetric dual spiral meander structure resonator performance results are shown in a return loss of -0.76 dB, an insertion loss of -46.32 dB, and a quality factor of 235 at 6.4 GHz C-band application. In addition, according to the design and performance of the resonator, we can derive from this performance a low phase noise oscillator. The oscillators using symmetric dual spiral meander structure resonator shows good phase noise performances of -104.43 dBc/Hz at a 100 kHz offset from the carrier frequencies of 6.38 GHz at output powers of 12.2 dBm, respectively.

  1. Observation of Discrete Oscillations in the Plot of Cosmological Scale Factor vs. Lookback Time

    NASA Astrophysics Data System (ADS)

    Ringermacher, Harry I.; Mead, Lawrence R

    2014-06-01

    We have observed damped longitudinal cosmological-scale oscillations in a unique model-independent plot of scale factor against lookback time. We measured 2 full, constant frequency, oscillations with a period of 0.15 Hubble times. This period corresponds to a fundamental frequency of approximately 7 cycles over the age of the universe, which we term 7 “Hubble-Hertz” (HHz). Transition-z values quoted in the literature generally fall near these oscillation minima and may explain the reported spread and deviation from the predicted ΛCDM value of approximately z = 0.77. We also observe second and third harmonics of the fundamental consistent with the spectrum of a sawtooth waveform. We propose a cosmological scalar field damped simple harmonic oscillator model for the observation - which fits well. On this time scale, the scalar field particle mass is extraordinarily small at 10^ -32 ev. Particles on this scale have been suggested in the literature as being associated with massive gravitons, in which case we may be observing longitudinal mode gravitational waves. A multiverse 5-D brane collision scenario is one possible source for the scalar field and waves. This scenario enables an estimate of the compacted 5th dimension radius at approximately 1,000,000 ly - the size of a galaxy dark matter halo. Our scalar field density parameter precisely replaces the ΛCDM dark matter density parameter in the Friedmann equations, resulting in identical data fits, and its present value matches the Planck value. We therefore posit that this scalar field manifests itself as the dark matter.

  2. Role of APOBEC3F Gene Variation in HIV-1 Disease Progression and Pneumocystis Pneumonia

    PubMed Central

    An, Ping; Penugonda, Sudhir; Thorball, Christian W.; Bartha, Istvan; Goedert, James J.; Donfield, Sharyne; Buchbinder, Susan; Binns-Roemer, Elizabeth; Kirk, Gregory D.; Zhang, Wenyan; Fellay, Jacques; Yu, Xiao-Fang; Winkler, Cheryl A.

    2016-01-01

    Human APOBEC3 cytidine deaminases are intrinsic resistance factors to HIV-1. However, HIV-1 encodes a viral infectivity factor (Vif) that degrades APOBEC3 proteins. In vitro APOBEC3F (A3F) anti-HIV-1 activity is weaker than A3G but is partially resistant to Vif degradation unlike A3G. It is unknown whether A3F protein affects HIV-1 disease in vivo. To assess the effect of A3F gene on host susceptibility to HIV- acquisition and disease progression, we performed a genetic association study in six well-characterized HIV-1 natural cohorts. A common six-Single Nucleotide Polymorphism (SNP) haplotype of A3F tagged by a codon-changing variant (p. I231V, with allele (V) frequency of 48% in European Americans) was associated with significantly lower set-point viral load and slower rate of progression to AIDS (Relative Hazards (RH) = 0.71, 95% CI: 0.56, 0.91) and delayed development of pneumocystis pneumonia (PCP) (RH = 0.53, 95% CI: 0.37–0.76). A validation study in the International Collaboration for the Genomics of HIV (ICGH) showed a consistent association with lower set-point viral load. An in vitro assay revealed that the A3F I231V variant may influence Vif mediated A3F degradation. Our results provide genetic epidemiological evidence that A3F modulates HIV-1/AIDS disease progression. PMID:26942578

  3. Role of APOBEC3F Gene Variation in HIV-1 Disease Progression and Pneumocystis Pneumonia.

    PubMed

    An, Ping; Penugonda, Sudhir; Thorball, Christian W; Bartha, Istvan; Goedert, James J; Donfield, Sharyne; Buchbinder, Susan; Binns-Roemer, Elizabeth; Kirk, Gregory D; Zhang, Wenyan; Fellay, Jacques; Yu, Xiao-Fang; Winkler, Cheryl A

    2016-03-01

    Human APOBEC3 cytidine deaminases are intrinsic resistance factors to HIV-1. However, HIV-1 encodes a viral infectivity factor (Vif) that degrades APOBEC3 proteins. In vitro APOBEC3F (A3F) anti-HIV-1 activity is weaker than A3G but is partially resistant to Vif degradation unlike A3G. It is unknown whether A3F protein affects HIV-1 disease in vivo. To assess the effect of A3F gene on host susceptibility to HIV- acquisition and disease progression, we performed a genetic association study in six well-characterized HIV-1 natural cohorts. A common six-Single Nucleotide Polymorphism (SNP) haplotype of A3F tagged by a codon-changing variant (p. I231V, with allele (V) frequency of 48% in European Americans) was associated with significantly lower set-point viral load and slower rate of progression to AIDS (Relative Hazards (RH) = 0.71, 95% CI: 0.56, 0.91) and delayed development of pneumocystis pneumonia (PCP) (RH = 0.53, 95% CI: 0.37-0.76). A validation study in the International Collaboration for the Genomics of HIV (ICGH) showed a consistent association with lower set-point viral load. An in vitro assay revealed that the A3F I231V variant may influence Vif mediated A3F degradation. Our results provide genetic epidemiological evidence that A3F modulates HIV-1/AIDS disease progression. PMID:26942578

  4. Study of factors determining the radiation sensitivity of quartz crystal oscillators (A0189)

    NASA Technical Reports Server (NTRS)

    Venables, J. D.; Ahearn, J. S.

    1984-01-01

    The correlation between defect cluster concentrations observed for different grades of quartz examined by transmission electron microscopy (TEM) and the electrical stability of quartz resonators exposed to complex radiation in an orbital LDEF was determined. It is demonstrated that the technique TEM provides a powerful method for studying the effect of radiation on crystalline quartz. Two factors suggest that the observed clusters may be responsible for the radiation-induced frequency drift and acoustic absorption effects associated with irradiated quartz resonators: (1) the clusters are expected to be very effective in modifying the piezoelectric properties of quartz because of the large strain fields associated with them; (2) both phenomena appear to be sensitive to the impurity concentration. It is suggested that TEM can be used to classify grades of quartz according to their suitability for use in radiation-hard resonators. This technique may identify the impurities that are responsible and thereby effect an improvement in the stability of quartz oscillators.

  5. Meteorological factors and El Niño Southern Oscillation are independently associated with dengue infections.

    PubMed

    Earnest, A; Tan, S B; Wilder-Smith, A

    2012-07-01

    Our objective was to determine the association between temperature, humidity, rainfall and dengue activity in Singapore, after taking into account lag periods as well as long-term climate variability such as the El Niño Southern Oscillation Index (SOI). We used a Poisson model which allowed for autocorrelation and overdispersion in the data. We found weekly mean temperature and mean relative humidity as well as SOI to be significantly and independently associated with dengue notifications. There was an interaction effect by periods of dengue outbreaks, but periods where El Niño was present did not moderate the relationship between humidity and temperature with dengue notifications. Our results help to understand the temporal trends of dengue in Singapore, and further reinforce the findings that meteorological factors are important in the epidemiology of dengue. PMID:21906411

  6. Rapid and Sustained Nuclear-Cytoplasmic ERK Oscillations Induced by Epidermal Growth Factor

    SciTech Connect

    Shankaran, Harish; Ippolito, Danielle L.; Chrisler, William B.; Resat, Haluk; Bollinger, Nikki; Opresko, Lee K.; Wiley, H. S.

    2009-12-01

    Mathematical modeling has predicted that ERK activity should oscillate in response to cell stimulation, but this has never been observed. To explore this inconsistency, we expressed an ERK1-GFP fusion protein in mammary epithelial cells. Following EGF stimulation, we observed rapid and continuous ERK oscillations between the nucleus and cytoplasm with a periodicity of approximately 15 minutes. These oscillations were remarkably persistent (>45 cycles), displayed an asymmetric waveform, and were highly dependent on cell density, essentially disappearing at confluency. We conclude that the ERK pathway is an intrinsic oscillator. Although the functional implications of the observed oscillations are uncertain, this property can be used to continuously monitor ERK activity in single cells.

  7. Free oscillation rheometry monitoring of haemodilution and hypothermia and correction with fibrinogen and factor XIII concentrates

    PubMed Central

    2013-01-01

    Background Haemodilution and hypothermia induce coagulopathy separately, but their combined effect on coagulation has not been widely studied. Fibrinogen concentrate can correct dilutional coagulopathy and has an additional effect when combined with factor XIII concentrate. However, their effect on dilutional coagulopathy concomitant with hypothermia has not been studied previously. Free oscillation rheometry – FOR (Reorox®) – is a novel viscoelastic haemostatic assay that has not been studied in this context before. Methods Blood from 10 healthy volunteers was diluted by 33% with hydroxyethyl starch or Ringer’s acetate solutions. Effects of fibrinogen added in vitro with and without factor XIII were studied at 33°C and 37°C. Coagulation velocity (coagulation time) and clot strength (elasticity) were assessed with FOR. Coagulation was initiated in vitro with thromboplastin alone, or thromboplastin plus a platelet inhibitor. Results Hydroxyethyl starch increased the coagulation time and decreased clot strength significantly more than Ringer’s acetate solution, both in the presence and absence of a platelet inhibitor. There was a significant interaction between haemodilution with hydroxyethyl starch and hypothermia, resulting in increased coagulation time. After addition of fibrinogen, coagulation time shortened and elasticity increased, with the exception of fibrinogen-dependent clot strength (i.e., elasticity in the presence of a platelet inhibitor) after hydroxyethyl starch haemodilution. Factor XIII had an additional effect with fibrinogen on fibrinogen-dependent clot strength in blood diluted with Ringer’s acetate solution. Hypothermia did not influence any of the coagulation factor effects. Conclusions Both haemodilution and mild hypothermia impaired coagulation. Coagulopathy was more pronounced after haemodilution with hydroxyethyl starch than with Ringer’s acetate. Addition of fibrinogen with factor XIII was unable to reverse hydroxyethyl

  8. Factors influencing the microwave pulse duration in a klystron-like relativistic backward wave oscillator

    SciTech Connect

    Xiao Renzhen; Zhang Xiaowei; Zhang Ligang; Li Xiaoze; Zhang Lijun

    2012-07-15

    In this paper, we analyze the factors that affect the microwave pulse duration in a klystron-like relativistic backward wave oscillator (RBWO), including the diode voltage, the guiding magnetic field, the electron beam collector, the extraction cavity, and the gap between the electron beam and the slow wave structure (SWS). The results show that the microwave pulse duration increases with the diode voltage until breakdown occurs on the surface of the extraction cavity. The pulse duration at low guiding magnetic field is generally 5-10 ns smaller than that at high magnetic field due to the asymmetric electron emission and the larger energy spread of the electron beam. The electron beam collector can affect the microwave pulse duration significantly because of the anode plasma generated by bombardment of the electron beam on the collector surface. The introduction of the extraction cavity only slightly changes the pulse duration. The decrease of the gap between the electron beam and the SWS can increase the microwave pulse duration greatly.

  9. Generation and Standardized, Systemic Phenotypic Analysis of Pou3f3L423P Mutant Mice

    PubMed Central

    Kumar, Sudhir; Rathkolb, Birgit; Kemter, Elisabeth; Sabrautzki, Sibylle; Michel, Dian; Adler, Thure; Becker, Lore; Beckers, Johannes; Busch, Dirk H.; Garrett, Lillian; Hans, Wolfgang; Hölter, Sabine M.; Horsch, Marion; Klingenspor, Martin; Klopstock, Thomas; Rácz, Ildikó; Rozman, Jan; Vargas Panesso, Ingrid Liliana; Vernaleken, Alexandra; Zimmer, Andreas; Fuchs, Helmut; Gailus-Durner, Valérie; Hrabě de Angelis, Martin; Wolf, Eckhard; Aigner, Bernhard

    2016-01-01

    Increased levels of blood plasma urea were used as phenotypic parameter for establishing novel mouse models for kidney diseases on the genetic background of C3H inbred mice in the phenotype-driven Munich ENU mouse mutagenesis project. The phenotypically recessive mutant line HST011 was established and further analyzed. The causative mutation was detected in the POU domain, class 3 transcription factor 3 (Pou3f3) gene, which leads to the amino acid exchange Pou3f3L423P thereby affecting the conserved homeobox domain of the protein. Pou3f3 homozygous knockout mice are published and show perinatal death. Line Pou3f3L423P is a viable mouse model harboring a homozygous Pou3f3 mutation. Standardized, systemic phenotypic analysis of homozygous mutants was carried out in the German Mouse Clinic. Main phenotypic changes were low body weight and a state of low energy stores, kidney dysfunction and secondary effects thereof including low bone mineralization, multiple behavioral and neurological defects including locomotor, vestibular, auditory and nociceptive impairments, as well as multiple subtle changes in immunological parameters. Genome-wide transcriptome profiling analysis of kidney and brain of Pou3f3L423P homozygous mutants identified significantly regulated genes as compared to wild-type controls. PMID:27003440

  10. Relaxation oscillations in optically pumped molecular lasers

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.; Koepf, G. A.

    1980-01-01

    The observation of relaxation oscillations in both the (C-13)H3F and (C-12)H3F optically pumped lasers is reported. Expressions are derived for the oscillation frequency and its temperature and pressure dependences using a four-level rate equation model. Excellent agreement between measured frequencies and the theory presented is observed. Models are considered for using this phenomenon to determine the rotational and vibrational relaxation mechanisms of the laser gases.

  11. TTF1, a homeodomain containing transcription factor, contributes to regulating periodic oscillations in GnRH gene expression

    PubMed Central

    Matagne, Valerie; Kim, Jae Geun; Ryu, Byung Jun; Hur, Min Kyu; Kim, Min Sung; Kim, Kyungjin; Park, Byong Seo; Damante, Giuseppe; Smiley, Gregory; Lee, Byung Ju; Ojeda, Sergio R.

    2012-01-01

    Thyroid transcription factor 1 (TTF1), a member of the NK family of transcription factors required for basal forebrain morphogenesis, functions in the postnatal hypothalamus as a transcriptional regulator of genes encoding neuromodulators and hypophysiotrophic peptides. One of these peptides is gonadotropin-releasing hormone (GnRH). Here we show that Ttf1 mRNA abundance vary in a diurnal and melatonin-dependent fashion in the preoptic area (POA) of the rat, with maximal Ttf1 expression attained during the dark phase of the light/dark cycle, preceding the nocturnal peak in GnRH mRNA content. GnRH promoter activity oscillates in a circadian manner in GT1-7 cells, and this pattern is enhanced by TTF1 and blunted by siRNA-mediated Ttf1 gene silencing. TTF1 trans-activates GnRH transcription by binding to two sites in the GnRH promoter. Rat GnRH neurons in situ contain key proteins components of the positive (BMAL1, CLOCK) and negative (PER1) limbs of the circadian oscillator, and these proteins repress Ttf1 promoter activity in vitro. In contrast, Ttf1 transcription is activated by CRY1, a clock component required for circadian rhythmicity. In turn, TTF1 represses transcription of Rev-erbα, a heme receptor that controls circadian transcription within the positive limb of the circadian oscillator. These findings suggest that TTF1 is a component of the molecular machinery controlling circadian oscillations in GnRH gene transcription. PMID:22356123

  12. Regulation of mTOR Signaling by Semaphorin 3F-Neuropilin 2 Interactions In Vitro and In Vivo

    PubMed Central

    Nakayama, Hironao; Bruneau, Sarah; Kochupurakkal, Nora; Coma, Silvia; Briscoe, David M.; Klagsbrun, Michael

    2015-01-01

    Semaphorin 3F (SEMA3F) provides neuronal guidance cues via its ability to bind neuropilin 2 (NRP2) and Plexin A family molecules. Recent studies indicate that SEMA3F has biological effects in other cell types, however its mechanism(s) of function is poorly understood. Here, we analyze SEMA3F-NRP2 signaling responses in human endothelial, T cell and tumor cells using phosphokinase arrays, immunoprecipitation and Western blot analyses. Consistently, SEMA3F inhibits PI-3K and Akt activity, and responses are associated with the disruption of mTOR/rictor assembly and mTOR-dependent activation of the RhoA GTPase. We also find that the expression of vascular endothelial growth factor, as well as mTOR-inducible cellular activation responses and cytoskeleton stability are inhibited by SEMA3F-NRP2 interactions in vitro. In vivo, local and systemic overproduction of SEMA3F reduces tumor growth in NRP2-expressing xenografts. Taken together, SEMA3F regulates mTOR signaling in diverse human cell types, suggesting that it has broad therapeutic implications. PMID:26156437

  13. Regulation of mTOR Signaling by Semaphorin 3F-Neuropilin 2 Interactions In Vitro and In Vivo.

    PubMed

    Nakayama, Hironao; Bruneau, Sarah; Kochupurakkal, Nora; Coma, Silvia; Briscoe, David M; Klagsbrun, Michael

    2015-01-01

    Semaphorin 3F (SEMA3F) provides neuronal guidance cues via its ability to bind neuropilin 2 (NRP2) and Plexin A family molecules. Recent studies indicate that SEMA3F has biological effects in other cell types, however its mechanism(s) of function is poorly understood. Here, we analyze SEMA3F-NRP2 signaling responses in human endothelial, T cell and tumor cells using phosphokinase arrays, immunoprecipitation and Western blot analyses. Consistently, SEMA3F inhibits PI-3K and Akt activity, and responses are associated with the disruption of mTOR/rictor assembly and mTOR-dependent activation of the RhoA GTPase. We also find that the expression of vascular endothelial growth factor, as well as mTOR-inducible cellular activation responses and cytoskeleton stability are inhibited by SEMA3F-NRP2 interactions in vitro. In vivo, local and systemic overproduction of SEMA3F reduces tumor growth in NRP2-expressing xenografts. Taken together, SEMA3F regulates mTOR signaling in diverse human cell types, suggesting that it has broad therapeutic implications. PMID:26156437

  14. Nonlinear Time Series Analysis of Nodulation Factor Induced Calcium Oscillations: Evidence for Deterministic Chaos?

    PubMed Central

    Hazledine, Saul; Sun, Jongho; Wysham, Derin; Downie, J. Allan; Oldroyd, Giles E. D.; Morris, Richard J.

    2009-01-01

    Legume plants form beneficial symbiotic interactions with nitrogen fixing bacteria (called rhizobia), with the rhizobia being accommodated in unique structures on the roots of the host plant. The legume/rhizobial symbiosis is responsible for a significant proportion of the global biologically available nitrogen. The initiation of this symbiosis is governed by a characteristic calcium oscillation within the plant root hair cells and this signal is activated by the rhizobia. Recent analyses on calcium time series data have suggested that stochastic effects have a large role to play in defining the nature of the oscillations. The use of multiple nonlinear time series techniques, however, suggests an alternative interpretation, namely deterministic chaos. We provide an extensive, nonlinear time series analysis on the nature of this calcium oscillation response. We build up evidence through a series of techniques that test for determinism, quantify linear and nonlinear components, and measure the local divergence of the system. Chaos is common in nature and it seems plausible that properties of chaotic dynamics might be exploited by biological systems to control processes within the cell. Systems possessing chaotic control mechanisms are more robust in the sense that the enhanced flexibility allows more rapid response to environmental changes with less energetic costs. The desired behaviour could be most efficiently targeted in this manner, supporting some intriguing speculations about nonlinear mechanisms in biological signaling. PMID:19675679

  15. Current-oscillator correlation and Fano factor spectrum of quantum shuttle with finite bias voltage and temperature.

    PubMed

    Lai, Wenxi; Cao, Yunshan; Ma, Zhongshui

    2012-05-01

    A general master equation is derived to describe an electromechanical single-dot transistor in the Coulomb blockade regime. In the equation, Fermi distribution functions in the two leads are taken into account, which allows one to study the system as a function of bias voltage and temperature of the leads. Furthermore, we treat the coherent interaction mechanism between electron tunneling events and the dynamics of excited vibrational modes. Stationary solutions of the equation are numerically calculated. We show that current through the oscillating island at low temperature appears to have step-like characteristics as a function of the bias voltage and the steps depend on the mean phonon number of the oscillator. At higher temperatures the current steps would disappear and this event is accompanied by the emergence of thermal noise of the charge transfer. When the system is mainly in the ground state, the zero frequency Fano factor of current manifests sub-Poissonian noise and when the system is partially driven into its excited states it exhibits super-Poissonian noise. The difference in the current noise would almost be removed for the situation in which the dissipation rate of the oscillator is much larger than the bare tunneling rates of electrons. PMID:22469613

  16. The Seasonal and Interannual Variability of the Budgets of N2O and CCl3F

    NASA Technical Reports Server (NTRS)

    Wong, Sun; Prather, Michael J.; Rind, David H.

    1999-01-01

    The 6-year wind archives from the Goddard Institute for Space Studies/Global Climate-Middle Atmosphere Model (GISS/GCMAM) were in- put to the GISS/Harvard/Irvine Chemical Transport Model (G/H/I CTM) to study the seasonal and interannual variability of the budgets and distributions of nitrous oxide (N2O) and trichlorofluoromethane (CCl3F), with the corresponding chemical loss frequencies recycled and boundary conditions kept unchanged from year to year. The effects of ozone feedback and quasi-biennial oscillation (QBO) were not included. However, the role of circulation variation in driving the lifetime variability is investigated. It was found that the global loss rates of these tracers are related to the extratropical planetary wave activity, which drives the tropical upward mass flux. For N2O, a semiannual signal in the loss rate variation is associated with the interhemispheric asymmetry in the upper stratospheric wave activity. For CCl3F, the semiannual signal is weaker, associated with the comparatively uniform wave episodes in the lower stratosphere. The loss rates lag behind the wave activity by about 1-2 months. The interannual variation of the GCM generated winds drives the interannual variation of the annually averaged lifetime. The year-to-year variations of the annually averaged lifetimes can be about 3% for N2O and 4% for CCl3F.

  17. Genetic Identification of SEMA3F as an Antilymphangiogenic Metastasis Suppressor Gene in Head and Neck Squamous Carcinoma.

    PubMed

    Doçi, Colleen L; Mikelis, Constantinos M; Lionakis, Michail S; Molinolo, Alfredo A; Gutkind, J Silvio

    2015-07-15

    Head and neck squamous cell carcinomas (HNSCC) often metastasize to locoregional lymph nodes, and lymph node involvement represents one of the most important prognostic factors of poor clinical outcome. HNSCCs are remarkably lymphangiogenic and represent a clear example of a cancer that utilizes the lymphatic vasculature for malignant dissemination; however, the molecular mechanisms underlying lymphangiogenesis in HNSCC is still poorly understood. Of interest, we found that an axon guidance molecule, Semaphorin 3F (SEMA3F), is among the top 1% underexpressed genes in HNSCC, and that genomic loss of SEMA3F correlates with increased metastasis and decreased survival. SEMA3F acts on its coreceptors, plexins and neuropilins, among which neuropilin-2 (NRP2) is highly expressed in lymphatic endothelial cells (LEC) but not in oral epithelium and most HNSCCs. We show that recombinant SEMA3F promotes LEC collapse and potently inhibits lymphangiogenesis in vivo. By reconstituting all possible plexin and neuropilin combinations, we found that SEMA3F acts through multiple receptors, but predominantly requires NRP2 to signal in LECs. Using orthotopic HNSCC metastasis mouse models, we provide direct evidence that SEMA3F re-expression diminishes lymphangiogenesis and lymph node metastasis. Furthermore, analysis of a large tissue collection revealed that SEMA3F is progressively lost during HNSCC progression, concomitant with increased tumor lymphangiogenesis. SEMA3F is localized to 3p21, an early and frequently deleted locus in HNSCC and many other prevalent human malignancies. Thus, SEMA3F may represent an antilymphangiogenic metastasis suppressor gene widely lost during cancer progression, hence serving as a prognostic biomarker and an attractive target for therapeutic intervention to halt metastasis. PMID:25952650

  18. Pou3f4-Mediated Regulation of Ephrin-B2 Controls Temporal Bone Development in the Mouse

    PubMed Central

    Raft, Steven; Coate, Thomas M.; Kelley, Matthew W.; Crenshaw, E. Bryan; Wu, Doris K.

    2014-01-01

    The temporal bone encases conductive and sensorineural elements of the ear. Mutations of POU3F4 are associated with unique temporal bone abnormalities and X-linked mixed deafness (DFNX2/DFN3). However, the target genes and developmental processes controlled by POU3F4 transcription factor activity have remained largely uncharacterized. Ephrin-B2 (Efnb2) is a signaling molecule with well-documented effects on cell adhesion, proliferation, and migration. Our analyses of targeted mouse mutants revealed that Efnb2 loss-of-function phenocopies temporal bone abnormalities of Pou3f4 hemizygous null neonates: qualitatively identical malformations of the stapes, styloid process, internal auditory canal, and cochlear capsule were present in both mutants. Using failed/insufficient separation of the stapes and styloid process as a quantitative trait, we found that single gene Efnb2 loss-of-function and compound Pou3f4/Efnb2 loss-of-function caused a more severe phenotype than single gene Pou3f4 loss-of-function. Pou3f4 and Efnb2 gene expression domains overlapped at the site of impending stapes-styloid process separation and at subcapsular mesenchyme surrounding the cochlea; at both these sites, Efnb2 expression was attenuated in Pou3f4 hemizygous null mutants relative to control. Results of immunoprecipitation experiments using chromatin isolated from nascent middle ear mesenchyme supported the hypothesis of a physical association between Pou3f4 and specific non-coding sequence of Efnb2. We propose that Efnb2 is a target of Pou3f4 transcription factor activity and an effector of mesenchymal patterning during temporal bone development. PMID:25299585

  19. Temperature dependent luminescence characteristics of KBe2BO3F2 and RbBe2BO3F2

    NASA Astrophysics Data System (ADS)

    Martincik, J.; Babin, V.; Liu, L.; Wang, X.; Chen, C. T.; Beitlerova, A.; Mihokova, E.; Nikl, M.

    2015-04-01

    This paper reports on a study of the luminescence characteristics of KBe2BO3F2 (KBBF) and RbBe2BO3F2(RBBF) crystals in UV/visible spectral range. The KBBF crystals are very popular for their nonlinear optical properties, however they have a potential to be used as scintillators for neutron detection. To determine the effectiveness of KBBF scintillation we combine the results from measurements of optical absorption; radioluminescence; light yield; photoluminescence and decay kinetics in the temperature range 8-330 K. Temperature dependence of luminescence in KBBF crystals is discussed.

  20. NbRABG3f, a member of Rab GTPase, is involved in Bamboo mosaic virus infection in Nicotiana benthamiana.

    PubMed

    Huang, Ying-Ping; Jhuo, Jia-Hua; Tsai, Meng-Shan; Tsai, Ching-Hsiu; Chen, Hong-Chi; Lin, Na-Sheng; Hsu, Yau-Heiu; Cheng, Chi-Ping

    2016-06-01

    The screening of differentially expressed genes in plants after pathogen infection can uncover the potential host factors required for the pathogens. In this study, an up-regulated gene was identified and cloned from Nicotiana benthamiana plants after Bamboo mosaic virus (BaMV) inoculation. The up-regulated gene was identified as a member of the Rab small guanosine triphosphatase (GTPase) family, and was designated as NbRABG3f according to its in silico translated product with high identity to that of RABG3f of tomato. Knocking down the expression of NbRABG3f using a virus-induced gene silencing technique in a protoplast inoculation assay significantly reduced the accumulation of BaMV. A transiently expressed NbRABG3f protein in N. benthamiana plants followed by BaMV inoculation enhanced the accumulation of BaMV to approximately 150%. Mutants that had the catalytic site mutation (NbRABG3f/T22N) or had lost their membrane-targeting capability (NbRABG3f/ΔC3) failed to facilitate the accumulation of BaMV in plants. Because the Rab GTPase is responsible for vesicle trafficking between organelles, a mutant with a fixed guanosine diphosphate form was used to identify the donor compartment. The use of green fluorescent protein (GFP) fusion revealed that GFP-NbRABG3f/T22N clearly co-localized with the Golgi marker. In conclusion, BaMV may use NbRABG3f to form vesicles derived from the Golgi membrane for intracellular trafficking to deliver unidentified factors to its replication site; thus, both GTPase activity and membrane-targeting ability are crucial for BaMV accumulation at the cell level. PMID:26416342

  1. Meteorological factors and El Nino Southern Oscillation are associated with paediatric varicella infections in Hong Kong, 2004-2010.

    PubMed

    Chan, J Y C; Lin, H L; Tian, L W

    2014-07-01

    Varicella accounts for substantial morbidities and remains a public health issue worldwide, especially in children. Little is known about the effect of meteorological variables on varicella infection risk for children. This study described the epidemiology of paediatric varicella notifications in Hong Kong from 2004 to 2010, and explored the association between paediatric varicella notifications in children aged <18 years and various meteorological factors using a time-stratified case-crossover model, with adjustment of potential confounding factors. The analysis found that daily mean temperature, atmospheric pressure and Southern Oscillation Index (SOI) were positively associated with paediatric varicella notifications. We found that an interquartile range (IQR) increase in temperature (8·38°C) at lag 1 day, a 9·50 hPa increase in atmospheric pressure for the current day, and a 21·91 unit increase in SOI for the current day may lead to an increase in daily cases of 5·19% [95% confidence interval (CI) 1·90-8·58], 5·77% (95% CI 3·01-8·61), and 4·32% (95% CI 2·98-5·68), respectively. An IQR increase in daily relative humidity (by 11·96%) was associated with a decrease in daily paediatric varicella (-2·79%, 95% CI -3·84 to -1·73). These findings suggest that meteorological factors might be important predictors of paediatric varicella infection in Hong Kong. PMID:24074377

  2. Partial discharges and breakdown in C3F8

    NASA Astrophysics Data System (ADS)

    Koch, M.; Franck, C. M.

    2014-10-01

    Traditional search processes of gases or gas mixtures for replacing SF6 involve time consuming measurements of partial discharges and breakdown behaviour for several voltage waveforms and different field configurations. Recently a model for prediction of this behaviour for SF6 was described in literature. The model only requires basic properties of the gas such as the critical field strength and the effective ionization coefficient, which can be obtained by swarm parameter measurements, and thermodynamic properties, which can be calculated. In this paper, we show for the well-known and electronegative gas octafluoropropane (C3F8) that it is possible to transfer the model developed for SF6 to this gas to describe the breakdown behaviour of C3F8. Thus the model can be beneficial in the screening process of new insulation gases.

  3. Structural determinants of HIV-1 Vif susceptibility and DNA binding in APOBEC3F

    PubMed Central

    Siu, Karen K.; Sultana, Azmiri; Azimi, Farshad C.; Lee, Jeffrey E.

    2016-01-01

    The human APOBEC3 family of DNA cytosine deaminases serves as a front-line intrinsic immune response to inhibit the replication of diverse retroviruses. APOBEC3F and APOBEC3G are the most potent factors against HIV-1. As a countermeasure, HIV-1 viral infectivity factor (Vif) targets APOBEC3s for proteasomal degradation. Here, we report the crystal structure of the Vif-binding domain in APOBEC3F and a novel assay to assess Vif-APOBEC3 binding. Our results point to an amphipathic surface that is conserved in APOBEC3s as critical for Vif susceptibility in APOBEC3F. Electrostatic interactions likely mediate Vif binding. Moreover, structure-guided mutagenesis reveals a straight ssDNA-binding groove distinct from the Vif-binding site, and a novel ‘aromatic switch’ is proposed to explain DNA substrate specificities across the APOBEC3 family. This study opens new lines of inquiry that will further our understanding of APOBEC3-mediated retroviral restriction and provides an accurate template for structure-guided development of inhibitors targeting the APOBEC3-Vif axis. PMID:24185281

  4. A Control Based System of Mechanical Loss Measurement for High Quality Factor Oscillators

    NASA Astrophysics Data System (ADS)

    Louis Gitelman, Louis; Smith, Nicolas; Jafar, Isaac; Harry, Gregory; Newport, Jonathan; Abernathy, Matt; LIGO Collaboration

    In this poster we will present the control system being developed to measure the quality factor of optics used in the Advanced LIGO gravitational wave detectors to predict thermal noise levels. It works by locking the phase between the optic's exciter and normal mode to pi/2 and locking the optics's amplitude allowing one to equate the energy output of the exciter to the mechanical loss of the optic. To do this the amplitude of the normal mode is detected using a birefringence meter and lockin amplifier, which is then fedback to an electrostatic exciter to control the mode's amplitude and phase with a PID controller written on a python script. The poster will discuss the components and assembly of this system and the theoretical control structure behind it. It will also discuss the speed, accuracy and general feasibility of this method of quality factor measurement relative to other methods, and steps to improve and develop this method of quality factor measurement and the possible applications for LIGO and in general.

  5. Cytoplasmic mislocalization of POU3F4 due to novel mutations leads to deafness in humans and mice.

    PubMed

    Parzefall, Thomas; Shivatzki, Shaked; Lenz, Danielle R; Rathkolb, Birgit; Ushakov, Kathy; Karfunkel, Daphne; Shapira, Yisgav; Wolf, Michael; Mohr, Manuela; Wolf, Eckhard; Sabrautzki, Sibylle; de Angelis, Martin Hrabé; Frydman, Moshe; Brownstein, Zippora; Avraham, Karen B

    2013-08-01

    POU3F4 is a POU domain transcription factor that is required for hearing. In the ear, POU3F4 is essential for mesenchymal remodeling of the bony labyrinth and is the causative gene for DFNX2 human nonsyndromic deafness. Ear abnormalities underlie this form of deafness, characterized previously in multiple spontaneous, radiation-induced and transgenic mouse mutants. Here, we report three novel mutations in the POU3F4 gene that result in profound hearing loss in both humans and mice. A p.Gln79* mutation was identified in a child from an Israeli family, revealed by massively parallel sequencing (MPS). This strategy demonstrates the strength of MPS for diagnosis with only one affected individual. A second mutation, p.Ile285Argfs*43, was identified by Sanger sequencing. A p.Cys300* mutation was found in an ENU-induced mutant mouse, schwindel (sdl), by positional cloning. The mutation leads to a predicted truncated protein, similar to the human mutations, providing a relevant mouse model. The p.Ile285Argfs*43 and p.Cys300* mutations lead to a shift of Pou3f4 nuclear localization to the cytoplasm, demonstrated in cellular localization studies and in the inner ears of the mutant mice. The discovery of these mutations facilitates a deeper comprehension of the molecular basis of inner ear defects due to mutations in the POU3F4 transcription factor. PMID:23606368

  6. Homogeneous and Heterogeneous Reaction Mechanisms in CH3F-O2 Inductively Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Donnelly, Vincent M.; Karakas, Erdinc; Kaler, Sanbir; Lou, Qiaowei; Economou, Demetre J.

    2013-09-01

    CH3F/O2 containing plasmas are used in selective Si3N4 etching over Si or SiO2. Fundamental plasma studies in these gas mixtures are scarce. In this work, optical emission rare gas actinometry and a global chemistry model were employed to study inductively couple plasmas in CH3F/O2 gas mixtures. For constant CH3F and O2 flow rates, the absolute H, F and O atom densities increased linearly with power. The feedstock gas was highly dissociated and most of the fluorine and oxygen was contained in reaction products HF, CO, CO2, H2O and OH. Measured number densities as a function of O2 addition to CH3F/O2 changed abruptly for H, O, and particularly F atoms (factor of 4) at 48% O2 A corresponding transition was also observed in electron density, electron temperature and gas temperature, as well as in C, CF and CH optical emission. These abrupt transitions were attributed to the reactor wall reactivity, changing from a polymer-coated surface to a polymer-free surface, and vice-versa, as the O2 content in the feed gas crossed 48%. Homogeneous chemistry dominates above 48% O2; a kinetic model with no adjustable parameters is in excellent agreement with the absolute F and H and relative HF number density dependence on power and pressure. CH3F/O2 containing plasmas are used in selective Si3N4 etching over Si or SiO2. Fundamental plasma studies in these gas mixtures are scarce. In this work, optical emission rare gas actinometry and a global chemistry model were employed to study inductively couple plasmas in CH3F/O2 gas mixtures. For constant CH3F and O2 flow rates, the absolute H, F and O atom densities increased linearly with power. The feedstock gas was highly dissociated and most of the fluorine and oxygen was contained in reaction products HF, CO, CO2, H2O and OH. Measured number densities as a function of O2 addition to CH3F/O2 changed abruptly for H, O, and particularly F atoms (factor of 4) at 48% O2 A corresponding transition was also observed in electron density

  7. Nuclear import of APOBEC3F-labeled HIV-1 preintegration complexes.

    PubMed

    Burdick, Ryan C; Hu, Wei-Shau; Pathak, Vinay K

    2013-12-01

    Human cytidine deaminases APOBEC3F (A3F) and APOBEC3G (A3G) are host factors that incorporate into virions and restrict virus replication. We labeled HIV-1 particles with yellow fluorescent protein (YFP)-tagged APOBEC3 proteins and examined their association with preintegration complexes (PICs) in infected cells. Labeling of PICs with A3F-YFP, and to a lesser extent A3G-YFP, could be used to visualize PICs in the nuclei, which was dependent on nuclear pore protein Nup153 but not TNPO3. We show that reverse transcription is not required for nuclear import of PICs, indicating that a viral core uncoating event associated with reverse transcription, and the central DNA flap that forms during reverse transcription, are not required for nuclear import. We also quantify association of cytoplasmic PICs with nuclear envelope (NE) and report that capsid mutations that increase or decrease core stability dramatically reduce NE association and nuclear import of PICs. In addition, we find that nuclear PICs remain close to the NE and are not distributed throughout the nuclei. These results provide tools for tracking retroviral PICs in infected cells and reveal insights into HIV-1 replication. PMID:24248339

  8. ABET Criterion 3.f: how much curriculum content is enough?

    PubMed

    Barry, B E; Ohland, M W

    2012-06-01

    Even after multiple cycles of ABET accreditation, many engineering programs are unsure of how much curriculum content is needed to meet the requirements of ABET's Criterion 3.f (an understanding of professional and ethical responsibility). This study represents the first scholarly attempt to assess the impact of curriculum reform following the introduction of ABET Criterion 3.f. This study sought to determine how much professional and ethical responsibility curriculum content was used between 1995 and 2005, as well as how, when, why, and to what effect changes in the amount of content occurred. Subsequently, the study sought to evaluate if different amounts of curriculum content generated differing student outcomes. The amount of curriculum content used by each of the participating programs was identified during semi-structured interviews with program administrators and a review of ABET Self-Study documents. Quantitative methods were applied to determine if a relationship existed between the curriculum content and performance on a nationally administered, engineering-specific standardized examination. The findings indicate a statistical relationship, but a lack of structure between the amount of required content in the curriculum and performance on the examination. Additional findings were also generated regarding the way that programs interpret the Criterion 3.f feedback generated during accreditation visits. The primary impact of this study is that it dispels the myth that more courses or course time on professionalism and ethics will necessarily lead to positive engineering education outcomes. Much of the impetus to add more curriculum content results from a lack of conclusive feedback during ABET accreditation visits. PMID:21318324

  9. Angular-Dependent Phase Factor of Shubnikov-de Haas Oscillations in the Dirac Semimetal Cd3As2

    NASA Astrophysics Data System (ADS)

    Xiang, Z. J.; Zhao, D.; Jin, Z.; Shang, C.; Ma, L. K.; Ye, G. J.; Lei, B.; Wu, T.; Xia, Z. C.; Chen, X. H.

    2015-11-01

    We measure the magnetotransport properties of the three-dimensional Dirac semimetal Cd3As2 single crystal under magnetic fields up to 36 T. Shubnikov-de Haas (SdH) oscillations are clearly resolved and the n =1 Landau level is reached. A detailed analysis on the intercept of the Landau index plot reveals a significant dependence of the SdH phase factor on the orientation of the applied magnetic field. When the magnetic field is applied in the [001] direction, i.e., along the fourfold screw axis of the tetragonal crystal structure, a nontrivial π Berry phase, as predicted for the Dirac fermions, is observed. However, in a magnetic field tilted away from the [001] direction, the π Berry phase is evidently reduced, and a considerable enhancement of the effective mass is also revealed. Our observations demonstrate that the Dirac dispersion in Cd3As2 is effectively modified in a tilted magnetic field, whereas the preserved π Berry phase in a magnetic field along the [001] direction can be related to the realization of the Weyl fermions. The sudden change of the SdH phase also indicates a possible topological phase transition induced by the symmetry-breaking effect.

  10. Investigation of dielectric properties of cold C3F8 mixtures and hot C3F8 gas as Substitutes for SF6

    NASA Astrophysics Data System (ADS)

    Wang, Xiaohua; Zhong, Linlin; Yan, Jing; Yang, Aijun; Han, Guohui; Han, Guiquan; Wu, Yi; Rong, Mingzhe

    2015-10-01

    In order to reduce the global warming potential resulting from SF6 widely used as an insulating and arc quenching medium, the substitutes need to be found. This paper focuses on different cold C3F8 mixtures (at room temperature) as an insulating gas and hot C3F8 gas (at temperatures of 300-3500 K) as an arc quenching medium, which seem to be a good replacement of SF6. Firstly, the dielectric properties, including the reduced ionization coefficient α / N, reduced electron attachment coefficient η / N and reduced critical electric field strength ( E / N)cr, of the cold C3F8-CF4, C3F8-CO2, C3F8-N2, C3F8-O2 and C3F8-Ar mixtures are calculated numerically using the two-term approximation of the Boltzmann equation. The dependence of such dielectric properties on the buffer gas proportion is investigated. Among the various C3F8 mixtures, the C3F8-N2 mixture has the lowest α / N and the C3F8-CF4 mixture has the largest η / N, and moreover, the C3F8-N2 mixture is the best insulator in terms of breakdown strength because it has the largest ( E / N)cr. Secondly, the ( E / N)cr of hot C3F8 at temperatures up to 3500 K and various pressures is determined and compared with that of hot SF6 gas. It is found that the hot C3F8 gas has much poorer dielectric performance than hot SF6 because the ( E / N)cr of C3F8 decreases significantly above room temperature.

  11. Merlin/NF2 Regulates Angiogenesis in Schwannomas through a Rac1/Semaphorin 3F-Dependent Mechanism1

    PubMed Central

    Wong, Hon-Kit; Shimizu, Akio; Kirkpatrick, Nathaniel D; Garkavtsev, Igor; Chan, Annie W; di Tomaso, Emmanuelle; Klagsbrun, Michael; Jain, Rakesh K

    2012-01-01

    Neurofibromatosis type 2 (NF2) is an autosomal-dominant multiple neoplasia syndrome that results from mutations in the NF2 tumor suppressor gene. Patients with NF2 develop hallmark schwannomas that require surgery or radiation, both of which have significant adverse effects. Recent studies have indicated that the tumor microenvironment—in particular, tumor blood vessels—of schwannomas may be an important therapeutic target. Furthermore, although much has been done to understand how merlin, the NF2 gene product, functions as a tumor suppressor gene in schwannoma cells, the functional role of merlin in the tumor microenvironment and the mechanism(s) by which merlin regulates angiogenesis to support schwannoma growth is largely unexplored. Here we report that the expression of semaphorin 3F (SEMA3F) was specifically downregulated in schwannoma cells lacking merlin/NF2. When we reintroduced SEMA3F in schwannoma cells, we observed normalized tumor blood vessels, reduced tumor burden, and extended survival in nude mice bearing merlin-deficient brain tumors. Next, using chemical inhibitors and gene knockdown with RNA interference, we found that merlin regulated expression of SEMA3F through Rho GTPase family member Rac1. This study shows that, in addition to the tumor-suppressing activity of merlin, it also functions to maintain physiological angiogenesis in the nervous system by regulating antiangiogenic factors such as SEMA3F. Restoring the relative balance of proangiogenic and antiangiogenic factors, such as increases in SEMA3F, in schwannoma microenvironment may represent a novel strategy to alleviate the clinical symptoms of NF2-related schwannomas. PMID:22431917

  12. Fractional oscillator.

    PubMed

    Stanislavsky, A A

    2004-11-01

    We consider a fractional oscillator which is a generalization of the conventional linear oscillator in the framework of fractional calculus. It is interpreted as an ensemble average of ordinary harmonic oscillators governed by a stochastic time arrow. The intrinsic absorption of the fractional oscillator results from the full contribution of the harmonic oscillator ensemble: these oscillators differ a little from each other in frequency so that each response is compensated by an antiphase response of another harmonic oscillator. This allows one to draw a parallel in the dispersion analysis for media described by a fractional oscillator and an ensemble of ordinary harmonic oscillators with damping. The features of this analysis are discussed. PMID:15600586

  13. Comparative study of global warming effects during silicon nitride etching using C3F6O/O2 and C3F6/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Kim, Ka Youn; Moon, Hock Key; Lee, Nae-Eung; Hong, Bo Han; Oh, Soo Ho

    2015-01-01

    C3F6 and C3F6 gases were investigated as replacement gases for SF6 used in display industry due to their low global warming potential and short lifetime. In the C3F6/O2 and C3F6/O2 capacitively coupled plasmas, Si3N4 etch conditions were varied by controlling process parameters. The global warming effects were quantified as million metric ton carbon equivalents (MMTCEs) obtained from the volumetric emission of by-product and etch gases. A lower MMTCE value and higher etch rate process with combination of high and low source frequencies, f HF (27.12 MHz)/ f LF (2 MHz), were observed for the C3F6/O2 chemistry than for the C3F6/O2 chemistry.

  14. Electroporation of DC-3F cells is a dual process.

    PubMed

    Wegner, Lars H; Frey, Wolfgang; Silve, Aude

    2015-04-01

    Treatment of biological material by pulsed electric fields is a versatile technique in biotechnology and biomedicine used, for example, in delivering DNA into cells (transfection), ablation of tumors, and food processing. Field exposure is associated with a membrane permeability increase usually ascribed to electroporation, i.e., formation of aqueous membrane pores. Knowledge of the underlying processes at the membrane level is predominantly built on theoretical considerations and molecular dynamics (MD) simulations. However, experimental data needed to monitor these processes with sufficient temporal resolution are scarce. The whole-cell patch-clamp technique was employed to investigate the effect of millisecond pulsed electric fields on DC-3F cells. Cellular membrane permeabilization was monitored by a conductance increase. For the first time, to our knowledge, it could be established experimentally that electroporation consists of two clearly separate processes: a rapid membrane poration (transient electroporation) that occurs while the membrane is depolarized or hyperpolarized to voltages beyond so-called threshold potentials (here, +201 mV and -231 mV, respectively) and is reversible within ∼100 ms after the pulse, and a long-term, or persistent, permeabilization covering the whole voltage range. The latter prevailed after the pulse for at least 40 min, the postpulse time span tested experimentally. With mildly depolarizing or hyperpolarizing pulses just above threshold potentials, the two processes could be separated, since persistent (but not transient) permeabilization required repetitive pulse exposure. Conductance increased stepwise and gradually with depolarizing and hyperpolarizing pulses, respectively. Persistent permeabilization could also be elicited by single depolarizing/hyperpolarizing pulses of very high field strength. Experimental measurements of propidium iodide uptake provided evidence of a real membrane phenomenon, rather than a mere

  15. Crystal Structure of Te 2O 3F 2

    NASA Astrophysics Data System (ADS)

    Ider, A.; Laval, J. P.; Frit, B.; Carré, J.; Bastide, J. P.

    1996-04-01

    Te2O3F2crystallizes with the triclinic symmetry (space groupP-1) and the unit cell parametersa= 515.3(1) pm,b= 625.7(1) pm,c= 688.8(1) pm, α = 98.71(1)°, β = 110.31(1)°, γ = 92.72(1)°,Z= 2. Its structure was solved and refined toRvaluesR1= 0.024 and wR2= 0.059 on the basis of 699 independent reflections recorded on a single crystal with an automatic four-circle diffractometer. The two Te atoms are, respectively, fourfold and fivefold coordinated and their lone pairEis stereochemically active. The bond valence calculation shows a perfect O/F order. The Te(1)O3FEand Te(2)O4FEpolyhedra form, by sharing O-O edges, bipolyhedral units with a very short Te-Te distance (319 pm). These units, by sharing corners, constitute independent sheets parallel tox0y. All the F atoms are nonbridging and orientated, together with the lone pairsE, toward the interlayer space. The structural relationships with the α-TeO2structure have been evidenced and analyzed.

  16. Role of Acentric Displacements on the Crystal Structure and Second-Harmonic Generating Properties of RbPbCO3F and CsPbCO3F

    PubMed Central

    2015-01-01

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet–visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6̅m2 (crystal class 6̅m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even–odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb2+. The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

  17. Role of acentric displacements on the crystal structure and second-harmonic generating properties of RbPbCO3F and CsPbCO3F.

    PubMed

    Tran, T Thao; Halasyamani, P Shiv; Rondinelli, James M

    2014-06-16

    Two lead fluorocarbonates, RbPbCO3F and CsPbCO3F, were synthesized and characterized. The materials were synthesized through solvothermal and conventional solid-state techniques. RbPbCO3F and CsPbCO3F were structurally characterized by single-crystal X-ray diffraction and exhibit three-dimensional (3D) crystal structures consisting of corner-shared PbO6F2 polyhedra. For RbPbCO3F, infrared and ultraviolet-visible spectroscopy and thermogravimetric and differential thermal analysis measurements were performed. RbPbCO3F is a new noncentrosymmetric material and crystallizes in the achiral and nonpolar space group P6m2 (crystal class 6m2). Powder second-harmonic generation (SHG) measurements on RbPbCO3F and CsPbCO3F using 1064 nm radiation revealed an SHG efficiency of approximately 250 and 300 × α-SiO2, respectively. Charge constants d33 of approximately 72 and 94 pm/V were obtained for RbPbCO3F and CsPbCO3F, respectively, through converse piezoelectric measurements. Electronic structure calculations indicate that the nonlinear optical response originates from the distorted PbO6F2 polyhedra, because of the even-odd parity mixing of the O 2p states with the nearly spherically symmetric 6s electrons of Pb(2+). The degree of inversion symmetry breaking is quantified using a mode-polarization vector analysis and is correlated with cation size mismatch, from which it is possible to deduce the acentric properties of 3D alkali-metal fluorocarbonates. PMID:24867361

  18. Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber.

    PubMed

    Amole, C; Ardid, M; Asner, D M; Baxter, D; Behnke, E; Bhattacharjee, P; Borsodi, H; Bou-Cabo, M; Brice, S J; Broemmelsiek, D; Clark, K; Collar, J I; Cooper, P S; Crisler, M; Dahl, C E; Daley, S; Das, M; Debris, F; Dhungana, N; Farine, J; Felis, I; Filgas, R; Fines-Neuschild, M; Girard, F; Giroux, G; Hai, M; Hall, J; Harris, O; Jackson, C M; Jin, M; Krauss, C B; Lafrenière, M; Laurin, M; Lawson, I; Levine, I; Lippincott, W H; Mann, E; Martin, J P; Maurya, D; Mitra, P; Neilson, R; Noble, A J; Plante, A; Podviianiuk, R B; Priya, S; Robinson, A E; Ruschman, M; Scallon, O; Seth, S; Sonnenschein, A; Starinski, N; Štekl, I; Vázquez-Jáuregui, E; Wells, J; Wichoski, U; Zacek, V; Zhang, J

    2015-06-12

    New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of <3.5×10(-10) and an alpha rejection factor of >98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering. PMID:26196790

  19. Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber

    NASA Astrophysics Data System (ADS)

    Amole, C.; Ardid, M.; Asner, D. M.; Baxter, D.; Behnke, E.; Bhattacharjee, P.; Borsodi, H.; Bou-Cabo, M.; Brice, S. J.; Broemmelsiek, D.; Clark, K.; Collar, J. I.; Cooper, P. S.; Crisler, M.; Dahl, C. E.; Daley, S.; Das, M.; Debris, F.; Dhungana, N.; Farine, J.; Felis, I.; Filgas, R.; Fines-Neuschild, M.; Girard, F.; Giroux, G.; Hai, M.; Hall, J.; Harris, O.; Jackson, C. M.; Jin, M.; Krauss, C. B.; Lafrenière, M.; Laurin, M.; Lawson, I.; Levine, I.; Lippincott, W. H.; Mann, E.; Martin, J. P.; Maurya, D.; Mitra, P.; Neilson, R.; Noble, A. J.; Plante, A.; Podviianiuk, R. B.; Priya, S.; Robinson, A. E.; Ruschman, M.; Scallon, O.; Seth, S.; Sonnenschein, A.; Starinski, N.; Štekl, I.; Vázquez-Jáuregui, E.; Wells, J.; Wichoski, U.; Zacek, V.; Zhang, J.; PICO Collaboration

    2015-06-01

    New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of <3.5 ×1 0-10 and an alpha rejection factor of >98.2 %. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.

  20. Dark matter search results from the PICO-2L C$_3$F$_8$ bubble chamber

    DOE PAGESBeta

    Amole, C.

    2015-06-11

    New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of < 3.5 × 10–10 and an alpha rejection factor of > 98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate eventsmore » exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. Lastly, these data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.« less

  1. Neurodynamic oscillators

    NASA Technical Reports Server (NTRS)

    Espinosa, Ismael; Gonzalez, Hortensia; Quiza, Jorge; Gonazalez, J. Jesus; Arroyo, Ruben; Lara, Ritaluz

    1995-01-01

    Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.

  2. Galactic oscillations

    NASA Technical Reports Server (NTRS)

    Miller, R. H.

    1991-01-01

    Long-lived oscillations that act like normal modes are described. The total kinetic energy is found to vary with time by amounts far in excess of the fluctuations expected from the virial theorem, and the variation shows periodic patterns that suggest oscillations. Experimental results indicate that oscillation amplitudes depend on the nature of the model. It is noted that it is difficult to answer questions about likely amplitudes in real galaxies with any confidence at the present time.

  3. Calcium Oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent; Bird, Gary S.; Putney, James W.

    2011-01-01

    Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlying mechanism of calcium oscillations through the power of mathematical modeling. We also summarize recent findings on the role of calcium entry through store-operated channels in sustaining calcium oscillations and in the mechanism by which calcium oscillations couple to downstream effectors. PMID:21421924

  4. Ultrastable Cryogenic Microwave Oscillators

    NASA Astrophysics Data System (ADS)

    Mann, Anthony G.

    Ultrastable cryogenic microwave oscillators are secondary frequency standards in the microwave domain. The best of these oscillators have demonstrated a short term frequency stability in the range 10-14 to a few times 10-16. The main application for these oscillators is as flywheel oscillators for the next generation of passive atomic frequency standards, and as local oscillators in space telemetry ground stations to clean up the transmitter close in phase noise. Fractional frequency stabilities of passive atomic frequency standards are now approaching 3 x10^-14 /τ where τ is the measurement time, limited only by the number of atoms that are being interrogated. This requires an interrogation oscillator whose short-term stability is of the order of 10-14 or better, which cannot be provided by present-day quartz technology. Ultrastable cryogenic microwave oscillators are based on resonators which have very high electrical Q-factors. The resolution of the resonator's linewidth is typically limited by electronics noise to about 1ppm and hence Q-factors in excess of 108 are required. As these are only attained in superconducting cavities or sapphire resonators at low temperatures, use of liquid helium cooling is mandatory, which has so far restricted these oscillators to the research or metrology laboratory. Recently, there has been an effort to dispense with the need for liquid helium and make compact flywheel oscillators for the new generation of primary frequency standards. Work is under way to achieve this goal in space-borne and mobile liquid-nitrogen-cooled systems. The best cryogenic oscillators developed to date are the ``whispering gallery'' (WG) mode sapphire resonator-oscillators of NASA's Jet Propulsion Laboratory (JPL) and the University of Western Australia (UWA), as well as Stanford University's superconducting cavity stabilized oscillator (SCSO). All of these oscillators have demonstrated frequency

  5. The cooling capabilities of C2F6/C3F8 saturated fluorocarbon blends for the ATLAS silicon tracker

    NASA Astrophysics Data System (ADS)

    Bates, R.; Battistin, M.; Berry, S.; Bitadze, A.; Bonneau, P.; Bousson, N.; Boyd, G.; Botelho-Direito, J.; Crespo-Lopez, O.; DiGirolamo, B.; Doubek, M.; Giugni, D.; Hallewell, G.; Lombard, D.; Katunin, S.; McMahon, S.; Nagai, K.; Robinson, D.; Rossi, C.; Rozanov, A.; Vacek, V.; Zwalinski, L.

    2015-03-01

    We investigate and address the performance limitations of the ATLAS silicon tracker fluorocarbon evaporative cooling system operation in the cooling circuits of the barrel silicon microstrip (SCT) sub-detector. In these circuits the minimum achievable evaporation temperatures with C3F8 were higher than the original specification, and were thought to allow an insufficient safety margin against thermal runaway in detector modules subject to a radiation dose initially foreseen for 10 years operation at LHC. We have investigated the cooling capabilities of blends of C3F8 with molar admixtures of up to 25% C2F6, since the addition of the more volatile C2F6 component was expected to allow a lower evaporation temperature for the same evaporation pressure.A custom built recirculator allowed the in-situ preparation of C2F6/C3F8 blends. These were circulated through a representative mechanical and thermal setup reproducing an as-installed ATLAS SCT barrel tracker cooling circuit. Blend molar compositions were verified to a precision of 3.10-3 in a custom ultrasonic instrument.Thermal measurements in a range of C2F6/C3F8 blends were compared with measurements in pure C3F8. These indicated that a blend with 25% C2F6 would allow a reduction in evaporation temperature of around 9oC to below -15oC, even at the highest module power dissipations envisioned after 10 years operation at LHC. Such a reduction would allow more than a factor two in safety margin against temperature dependant leakage power induced thermal runaway.Furthermore, a blend containing up to 25% C2F6 could be circulated without changes to the on-detector elements of the existing ATLAS inner detector evaporative cooling system.

  6. Large-filling-factor giant Shubnikov-de Haas oscillations in the ultrahigh-mobility two-dimensional GaAs/AlGaAs electron system

    NASA Astrophysics Data System (ADS)

    Wang, Zhuo; Mani, Ramesh. G.; Wegscheider, Werner

    The observation of microwave-induced zero-resistance states (ZRS) produced new interest in transport studies of very high filling factors in the high mobility GaAs/AlGaAs 2D electron system. In particular, there has been interest in the study of the overlap of such ZRS with high filling factor quantum Hall effect. Ref. 1 reported different phase relations between oscillatory resistances at high filling factors. In an effort to clarify the observations, we examine the influence of a dc current bias on the lineshape of oscillatory resistances in the ultrahigh-mobility two-dimensional GaAs/AlGaAs electron system. With increasing dc current bias, a change is also observed in the characteristic lineshape of the SdH oscillations. To quantify the change, we carry out lineshape fits of the oscillatory resistance obtained at different dc bias. In this talk, we will summarize the results of the study.

  7. In-band pumped Ho3+:KY3F10 2 μm laser.

    PubMed

    Schellhorn, Martin; Parisi, Daniela; Veronesi, Stefano; Bolognesi, Giacomo; Eichhorn, Marc; Tonelli, Mauro

    2013-02-15

    We report the first observation to our knowledge of room-temperature continuous-wave laser operation on the (5)I(7)→(5)I(8) transition of Ho(3+) ions in a KY(3)F(10) single crystal. Using a Tm-doped silica fiber laser operating at 1938 nm as a pump source, a maximum laser power of 1.8 W was obtained at a wavelength of ~2040 nm for 27 W of absorbed pump power with a slope efficiency of 19.1% with respect to absorbed power. At low cavity output coupling, the lasing wavelength shifted to 2060.5 nm. The beam propagation factor (M(2)) was measured to be <1.06 at the maximum output power, confirming fundamental transverse-mode (TEM(00)) operation. Performing a Caird analysis, we determined resonator round-trip losses and intrinsic slope efficiency of 30% and 43.8%, respectively. PMID:23455117

  8. Boxing with neutrino oscillations

    NASA Astrophysics Data System (ADS)

    Wagner, D. J.; Weiler, Thomas J.

    1999-06-01

    We develop a characterization of neutrino oscillations based on the coefficients of the oscillating terms. These coefficients are individually observable; although they are quartic in the elements of the unitary mixing matrix, they are independent of the conventions chosen for the angle and phase parametrization of the mixing matrix. We call these reparametrization-invariant observables ``boxes'' because of their geometric relation to the mixing matrix, and because of their association with the Feynman box diagram that describes oscillations in field theory. The real parts of the boxes are the coefficients for the CP- or T-even oscillation modes, while the imaginary parts are the coefficients for the CP- or T-odd oscillation modes. Oscillation probabilities are linear in the boxes, so measurements can straightforwardly determine values for the boxes (which can then be manipulated to yield magnitudes of mixing matrix elements). We examine the effects of unitarity on the boxes and discuss the reduction of the number of boxes to a minimum basis set. For the three-generation case, we explicitly construct the basis. Using the box algebra, we show that CP violation may be inferred from measurements of neutrino flavor mixing even when the oscillatory factors have averaged. The framework presented here will facilitate general analyses of neutrino oscillations among n>=3 flavors.

  9. Boxing with neutrino oscillations

    SciTech Connect

    Wagner, D.J.; Weiler, T.J.

    1999-06-01

    We develop a characterization of neutrino oscillations based on the coefficients of the oscillating terms. These coefficients are individually observable; although they are quartic in the elements of the unitary mixing matrix, they are independent of the conventions chosen for the angle and phase parametrization of the mixing matrix. We call these reparametrization-invariant observables {open_quotes}boxes{close_quotes} because of their geometric relation to the mixing matrix, and because of their association with the Feynman box diagram that describes oscillations in field theory. The real parts of the boxes are the coefficients for the {ital CP}- or {ital T}-even oscillation modes, while the imaginary parts are the coefficients for the {ital CP}- or {ital T}-odd oscillation modes. Oscillation probabilities are linear in the boxes, so measurements can straightforwardly determine values for the boxes (which can then be manipulated to yield magnitudes of mixing matrix elements). We examine the effects of unitarity on the boxes and discuss the reduction of the number of boxes to a minimum basis set. For the three-generation case, we explicitly construct the basis. Using the box algebra, we show that {ital CP} violation may be inferred from measurements of neutrino flavor mixing even when the oscillatory factors have averaged. The framework presented here will facilitate general analyses of neutrino oscillations among n{ge}3 flavors. {copyright} {ital 1999} {ital The American Physical Society}

  10. Structural Insights into HIV-1 Vif-APOBEC3F Interaction

    PubMed Central

    Nakashima, Masaaki; Ode, Hirotaka; Kawamura, Takashi; Kitamura, Shingo; Naganawa, Yuriko; Awazu, Hiroaki; Tsuzuki, Shinya; Matsuoka, Kazuhiro; Nemoto, Michiko; Hachiya, Atsuko; Sugiura, Wataru; Yokomaku, Yoshiyuki; Watanabe, Nobuhisa

    2015-01-01

    ABSTRACT The HIV-1 Vif protein inactivates the cellular antiviral cytidine deaminase APOBEC3F (A3F) in virus-infected cells by specifically targeting it for proteasomal degradation. Several studies identified Vif sequence motifs involved in A3F interaction, whereas a Vif-binding A3F interface was proposed based on our analysis of highly similar APOBEC3C (A3C). However, the structural mechanism of specific Vif-A3F recognition is still poorly understood. Here we report structural features of interaction interfaces for both HIV-1 Vif and A3F molecules. Alanine-scanning analysis of Vif revealed that six residues located within the conserved Vif F1-, F2-, and F3-box motifs are essential for both A3C and A3F degradation, and an additional four residues are uniquely required for A3F degradation. Modeling of the Vif structure on an HIV-1 Vif crystal structure revealed that three discontinuous flexible loops of Vif F1-, F2-, and F3-box motifs sterically cluster to form a flexible A3F interaction interface, which represents hydrophobic and positively charged surfaces. We found that the basic Vif interface patch (R17, E171, and R173) involved in the interactions with A3C and A3F differs. Furthermore, our crystal structure determination and extensive mutational analysis of the A3F C-terminal domain demonstrated that the A3F interface includes a unique acidic stretch (L291, A292, R293, and E324) crucial for Vif interaction, suggesting additional electrostatic complementarity to the Vif interface compared with the A3C interface. Taken together, these findings provide structural insights into the A3F-Vif interaction mechanism, which will provide an important basis for development of novel anti-HIV-1 drugs using cellular cytidine deaminases. IMPORTANCE HIV-1 Vif targets cellular antiviral APOBEC3F (A3F) enzyme for degradation. However, the details on the structural mechanism for specific A3F recognition remain unclear. This study reports structural features of interaction

  11. K2Pb3(CO3)3F2 and KCdCO3F: Novel Fluoride Carbonates with Layered and 3D Framework Structures.

    PubMed

    Lin, Yuan; Hu, Chun-Li; Mao, Jiang-Gao

    2015-11-01

    Two new mixed metal fluoride carbonates, KCdCO3F and K2Pb3(CO3)3F2, have been synthesized by solvothermal and solid-state techniques. KCdCO3F crystallizes in the acentric nonpolar space group P6̅m2, and its structure features a three-dimensional anionic framework in which the CdCO3 layers are further interconnected by bridging F(-) anions with the negative charge balanced by K(+) cations. K2Pb3(CO3)3F2 crystallizes in the centrosymmetric space group P63/mmc, and its structure exhibits a layered anionic skeleton featuring corner-shared PbO6F and PbO6F2 polyhedra. UV-vis diffuse reflectance spectroscopy studies show that the short-wavelength absorption edges of KCdCO3F and K2Pb3(CO3)3F2 are 227 and 287 nm, respectively. The second harmonic generation (SHG) measurement reveals that KCdCO3F is a phase-matchable material for generation of doubled-frequency light at both 532 and 266 nm, with a large SHG response of approximately 5.2 times that of KH2PO4 (KDP) at 532 nm and a moderate SHG response of approximately 0.75 times that of β-BaB2O4 (BBO) at 266 nm. Therefore, it is a promising UV material for fourth harmonic generation on a 1064 nm Q-switched Nd:YAG laser. PMID:26488674

  12. Raindrop oscillations

    NASA Technical Reports Server (NTRS)

    Beard, K. V.

    1982-01-01

    A model of the change in shape of a raindrop is presented. Raindrops measured by two orthogonal cameras were classified by shape and orientation to determine the nature of the oscillation. A physical model based on potential energy was then developed to study the amplitude variation of oscillating drops. The model results show that oscillations occur about the equilibrium axis ratio, but the time average axis ratio if significantly more spherical for large amplitudes because of asymmetry in the surface potential energy. A generalization of the model to oscillations produced by turbulence yields average axis ratios that are consistent with the camera measurements. The model results for average axis ratios were applied to rainfall studies with a dual polarized radar.

  13. Microelectronic oscillator

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1969-01-01

    Bipolar transistor operated in a grounded base configuration is used as the inductor in a microelectronic oscillator. This configuration is employed using thin-film hybrid technology and is also applicable to monolithic technology.

  14. Power oscillator

    DOEpatents

    Gitsevich, Aleksandr

    2001-01-01

    An oscillator includes an amplifier having an input and an output, and an impedance transformation network connected between the input of the amplifier and the output of the amplifier, wherein the impedance transformation network is configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and wherein the impedance transformation network is configured to protect the input of the amplifier from a destructive feedback signal. One example of the oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  15. Energy-transfer mechanisms in the CH3F-SF6 optically pumped laser

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.; Koepf, G. A.

    1980-01-01

    The power of an optically pumped CH3F laser operating on the 496-micron line has been doubled with the addition of SF6 without any corresponding increase in pump absorption. It is suggested that a near-resonant energy transfer between CH3F and SF6 followed by SF6 deactivation is the mechanism responsible for the enhancement.

  16. Factors influencing the temporal growth rate of the high order TM{sub 0n} modes in the Ka-band overmoded Cherenkov oscillator

    SciTech Connect

    Wu, Dapeng Shu, Ting; Ju, Jinchuan

    2015-06-15

    When the wavelength of overmoded Cherenkov oscillator goes into Ka-band, power handling capacity becomes an essential issue. Using the TM{sub 02} mode or higher order TM{sub 0n} modes as the operating mode is a potential solution. This paper is aimed to find some proper parameters to make the temporal growth rate of the TM{sub 02} mode higher in our previously studied Gigawatt (GW)-class Ka band oscillator. An accurate and fast calculation method of the “hot” dispersion equation is derived for rectangular corrugated SWSs, which are widely used in the high frequency Cherenkov devices. Then, factors that affect the temporal growth rate of the high order TM{sub 0n} modes are analyzed, including the depth of corrugation, the radius of drift tube, and the diode voltage. Results show that, when parameters are chosen properly, the temporal growth rate of the TM{sub 02} mode can be as high as 0.3 ns{sup −1}.

  17. Semaphorin 3F and neuropilin-2 control the migration of human T-cell precursors.

    PubMed

    Mendes-da-Cruz, Daniella Arêas; Brignier, Anne Colette; Asnafi, Vahid; Baleydier, Frederic; Messias, Carolina Valença; Lepelletier, Yves; Bedjaoui, Nawel; Renand, Amedée; Smaniotto, Salete; Canioni, Danielle; Milpied, Pierre; Balabanian, Karl; Bousso, Philippe; Leprêtre, Stéphane; Bertrand, Yves; Dombret, Hervé; Ifrah, Norbert; Dardenne, Mireille; Macintyre, Elizabeth; Savino, Wilson; Hermine, Olivier

    2014-01-01

    Neuropilins and semaphorins are known as modulators of axon guidance, angiogenesis, and organogenesis in the developing nervous system, but have been recently evidenced as also playing a role in the immune system. Here we describe the expression and role of semaphorin 3F (SEMA3F) and its receptor neuropilin-2 (NRP2) in human T cell precursors. NRP2 and SEMA3F are expressed in the human thymus, in both lymphoid and non-lymphoid compartments. SEMA3F have a repulsive effect on thymocyte migration and inhibited CXCL12- and sphingosine-1-phosphate (S1P)-induced thymocyte migration by inhibiting cytoskeleton reorganization prior to stimuli. Moreover, NRP2 and SEMA3F are expressed in human T-cell acute lymphoblastic leukemia/lymphoma primary cells. In these tumor cells, SEMA3F also blocks their migration induced by CXCL12 and S1P. Our data show that SEMA3F and NRP2 are further regulators of human thymocyte migration in physiological and pathological conditions. PMID:25068647

  18. Programmable Oscillator

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Lee, Clement G.; Nguyen, Huy

    2011-01-01

    A programmable oscillator is a frequency synthesizer with an output phase that tracks an arbitrary function. An offset, phase-locked loop circuit is used in combination with an error control feedback loop to precisely control the output phase of the oscillator. To down-convert the received signal, several stages of mixing may be employed with the compensation for the time-base distortion of the carrier occurring at any one of those stages. In the Goldstone Solar System Radar (GSSR), the compensation occurs in the mixing from an intermediate frequency (IF), whose value is dependent on the station and band, to a common IF used in the final stage of down-conversion to baseband. The programmable oscillator (PO) is used in the final stage of down-conversion to generate the IF, along with a time-varying phase component that matches the time-base distortion of the carrier, thus removing it from the final down-converted signal.

  19. Be2BO3F: A Phase of Beryllium Fluoride Borate Derived from KBe2BO3F2 with Short UV Absorption Edge.

    PubMed

    Guo, Shu; Liu, Lijuan; Xia, Mingjun; Kang, Lei; Huang, Qian; Li, Chao; Wang, Xiaoyang; Lin, Zheshuai; Chen, Chuangtian

    2016-07-01

    A phase of beryllium fluoride borate Be2BO3F (BBF) was successfully developed and grown by spontaneous nucleation from high temperature solution. The crystal belongs to the trigonal space group of R3̅c (No. 167), with lattice parameters a = 4.442(1) Å, c = 24.956(5) Å, and Z = 2. It is constructed by the infinite planar [Be2BO3F2]∞ layers, in which the planar triangle [BO3](3-) and the tetrahedral [BeO3F](5-) anionic groups are arranged in parallel via corner-sharing O atoms in each ab plane. BBF is an incongruent compound and decomposes at about 650 °C. The deep-ultraviolet (DUV) transmittance spectrum reveals that its UV cutoff wavelength is down to ∼150 nm. Theoretical calculations show that BBF has a large birefringence (Δn = 0.13 at 200 nm), which mainly originates from the infinite planar [Be2BO3F2]∞ layers. In conclusion, BBF may be served as a potential DUV birefringent material. PMID:27332696

  20. Shock wave study of the thermal dissociations of C3F6 and c-C3F6. I. dissociation of hexafluoropropene.

    PubMed

    Cobos, C J; Sölter, L; Tellbach, E; Troe, J

    2014-07-10

    The thermal dissociation of C3F6 was studied between 1330 and 2210 K in shock waves monitoring the UV absorption of CF2. CF2 yields of about 2.6 per parent C3F6 were obtained at reactant concentrations of 500-1000 ppm in the bath gas Ar. These yields dropped to about 1.8 when reactant concentrations were lowered to 60 ppm. The increase of the CF2 yield with increasing concentration was attributed to bimolecular reactions between primary and secondary dissociation products. Quantum-chemical and kinetic modeling calculations helped to estimate the contributions from the various primary dissociation steps. It was shown that the measurements correspond to unimolecular reactions in their falloff range. Falloff representations of the rate constants are given, leading to an overall high pressure rate constant k∞ = 2.0 × 10(17)(-104 kcal mol(-1)/RT) s(-1) and a relative rate of about 2/3:1/3 for the reactions C3F6 → CF3CF + CF2 versus C3F6 → C2F3 + CF3. PMID:24905383

  1. Absolute Line Intensities in the ν 3Band of 12CH 3F by Diode-Laser Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lepère, Muriel; Blanquet, Ghislain; Walrand, Jacques

    1996-06-01

    Infrared absolute line intensities of the ν 3band of 12CH 3F have been measured around 9.5 μm using a diode-laser spectrometer. These line strengths were obtained from the equivalent width method and, for a few lines, by fitting a Rautian profile to the measured shape of the lines. From these results, we have deduced the vibrational bandstrength ( Sv0= 379.2 ± 5.9 cm -2·atm -1at 296 K) and the first Herman-Wallis factor (α = 0.35 × 10 -3± 0.10 × 10 -3).

  2. Global CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS): retrieval, climatologies and trends

    NASA Astrophysics Data System (ADS)

    Kellmann, Sylvia; von Clarmann, Thomas; Stiller, Gabriele P.; Eckert, Ellen; Glatthor, Norbert; Höpfner, Michael; Kiefer, Michael; Orphal, Johannes; Funke, Bernd; Grabowski, Udo; Linden, Andrea; Dutton, Geoffrey S.; Elkins, James. W.

    2013-04-01

    Vertical profiles of CFC-11 (CCl3F) and CFC-12 (CCl2F2) have been measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) with global coverage under daytime and nighttime conditions. Time series of altitude/latitude bins were fitted by a parametric approach including constant and linear terms, a quasi-biennial oscillation (QBO) proxy and sine and cosine terms of several periods. In the time series from 2002 to 2011, quasi-biennial and annual oscillations are clearly visible. A decrease of stratospheric CFC mixing ratios in response to the Montreal Protocol is observed for most altitudes and latitudes. However, the trends differ from the trends measured in the troposphere, even after consideration of the time lag accounting for the local age of stratospheric air. At some latitudes and altitudes, trends are even positive, and in some cases they can only be explained by decadal changes in atmospheric age of air spectra or vertical mixing patterns.

  3. STABILIZED OSCILLATOR

    DOEpatents

    Jessen, P.L.; Price, H.J.

    1958-03-18

    This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

  4. Solar Oscillations

    NASA Technical Reports Server (NTRS)

    Duvall, Thomas

    2004-01-01

    Oscillations were first detected in the solar photosphere in 1962 by Leighton and students. In 1970 it was calculated that these oscillations, with a period near five minutes, were the manifestations of acoustic waves trapped in the interior. The subsequent measurements of the frequencies of global oscillation modes from the spatio-temporal power spectrum of the waves made possible the refinement of solar interior models. Over the years, increased understanding of the nuclear reaction rates, the opacity, the equation of state, convection, and gravitational settling have resulted. Mass flows shift the frequencies of modes leading to very accurate measurements of the interior rotation as a function of radius and latitude. In recent years, analogues of terrestrial seismology have led to a tomography of the interior, including measurements of global north-south flows and flow and wave speed measurements below features such as sunspots. The future of helioseismology seems bright with the approval of NASA's Solar Dynamics Observatory mission, to be launched in 2008.

  5. Synthesis and crystal structure of two synthetic oxofluoride framework compounds--Co2TeO3F2 and Co2SeO3F2.

    PubMed

    Hu, Shichao; Johnsson, Mats

    2012-11-01

    Two new isostructural Co(2+) containing tellurium and selenium oxofluoride compounds Co(2)TeO(3)F(2) and Co(2)SeO(3)F(2) are synthesized and their structures determined by single crystal X-ray diffraction. They crystallize in the orthorhombic space group Pnma with the unit cell parameters a = 7.3810(5) Å, b = 10.1936(7) Å, c = 5.3013(3) Å and a = 7.2655(8) Å, b = 10.0013(13) Å, c = 5.3564(6) Å, respectively. The Co(II) ion has octahedral coordination [CoO(3)F(3)] and builds up a 3D framework by corner- and edge sharing. The Se(IV) and the Te(IV) ions have the coordinations [SeO(3)E] and [TeO(3)E] respectively where E is the lone-pair electrons. The Se(IV) and Te(IV) ions are isolated from each other and bond only to the [CoO(3)F(3)] polyhedra. The electronegative element fluorine takes the role of a network builder like oxygen and helps to form the 3D framework structure. This is a difference compared to many oxohalide compounds containing Cl and Br where the halide ions are terminating ions preventing a 3D network from being formed. Long range antiferromagnetic interactions dominate at temperatures < 20 K. The magnetic susceptibility follows the Curie-Weiss law above 25 K with the Curie constant C = 5.62 emu K mol(-1), the Weiss temperature θ = -56 K and the effective magnetic moment μ(eff) = 4.74 μ(B) per cobalt atom. PMID:22968840

  6. Neural Cell Adhesion Molecule NrCAM Regulates Semaphorin 3F-Induced Dendritic Spine Remodeling

    PubMed Central

    Demyanenko, Galina P.; Mohan, Vishwa; Zhang, Xuying; Brennaman, Leann H.; Dharbal, Katherine E.S.; Tran, Tracy S.; Manis, Paul B.

    2014-01-01

    Neuron-glial related cell adhesion molecule (NrCAM) is a regulator of axon growth and repellent guidance, and has been implicated in autism spectrum disorders. Here a novel postsynaptic role for NrCAM in Semaphorin3F (Sema3F)-induced dendritic spine remodeling was identified in pyramidal neurons of the primary visual cortex (V1). NrCAM localized to dendritic spines of star pyramidal cells in postnatal V1, where it was coexpressed with Sema3F. NrCAM deletion in mice resulted in elevated spine densities on apical dendrites of star pyramidal cells at both postnatal and adult stages, and electron microscopy revealed increased numbers of asymmetric synapses in layer 4 of V1. Whole-cell recordings in cortical slices from NrCAM-null mice revealed increased frequency of mEPSCs in star pyramidal neurons. Recombinant Sema3F-Fc protein induced spine retraction on apical dendrites of wild-type, but not NrCAM-null cortical neurons in culture, while re-expression of NrCAM rescued the spine retraction response. NrCAM formed a complex in brain with Sema3F receptor subunits Neuropilin-2 (Npn-2) and PlexinA3 (PlexA3) through an Npn-2-binding sequence (TARNER) in the extracellular Ig1 domain. A trans heterozygous genetic interaction test demonstrated that Sema3F and NrCAM pathways interacted in vivo to regulate spine density in star pyramidal neurons. These findings reveal NrCAM as a novel postnatal regulator of dendritic spine density in cortical pyramidal neurons, and an integral component of the Sema3F receptor complex. The results implicate NrCAM as a contributor to excitatory/inhibitory balance in neocortical circuits. PMID:25143608

  7. Progress in optical parametric oscillators

    NASA Technical Reports Server (NTRS)

    Fan, Y. X.; Byer, R. L.

    1984-01-01

    It is pointed out that tunable coherent sources are very useful for many applications, including spectroscopy, chemistry, combustion diagnostics, and remote sensing. Compared with other tunable sources, optical parametric oscillators (OPO) offer the potential advantage of a wide wavelength operating range, which extends from 0.2 micron to 25 microns. The current status of OPO is examined, taking into account mainly advances made during the last decade. Attention is given to early LiNbO3 parametric oscillators, problems which have prevented wide use of parametric oscillators, the demonstration of OPO's using urea and AgGaS2, progress related to picosecond OPO's, a breakthrough in nanosecond parametric oscillators, the first demonstration of a waveguide and fiber parametric amplification and generation, the importance of chalcopyrite crystals, and theoretical work performed with the aim to understand the factors affecting the parametric oscillator performance.

  8. 29 CFR 780.158 - Examples of other practices within section 3(f) if requirements are met.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Examples of other practices within section 3(f) if requirements are met. 780.158 Section 780.158 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR... within Section 3(f) § 780.158 Examples of other practices within section 3(f) if requirements are met....

  9. 29 CFR 780.158 - Examples of other practices within section 3(f) if requirements are met.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Examples of other practices within section 3(f) if requirements are met. 780.158 Section 780.158 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR... within Section 3(f) § 780.158 Examples of other practices within section 3(f) if requirements are met....

  10. 29 CFR 780.158 - Examples of other practices within section 3(f) if requirements are met.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Examples of other practices within section 3(f) if requirements are met. 780.158 Section 780.158 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR... within Section 3(f) § 780.158 Examples of other practices within section 3(f) if requirements are met....

  11. 29 CFR 780.158 - Examples of other practices within section 3(f) if requirements are met.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false Examples of other practices within section 3(f) if requirements are met. 780.158 Section 780.158 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR... within Section 3(f) § 780.158 Examples of other practices within section 3(f) if requirements are met....

  12. 29 CFR 780.158 - Examples of other practices within section 3(f) if requirements are met.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Examples of other practices within section 3(f) if requirements are met. 780.158 Section 780.158 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR... within Section 3(f) § 780.158 Examples of other practices within section 3(f) if requirements are met....

  13. Topological amplitudes in D decays to two pseudoscalars: A global analysis with linear S U (3 )F breaking

    NASA Astrophysics Data System (ADS)

    Müller, Sarah; Nierste, Ulrich; Schacht, Stefan

    2015-07-01

    We study decays of D0, D+, and Ds+ mesons into two pseudoscalar mesons by expressing the decay amplitudes in terms of topological amplitudes. Including consistently S U (3 )F breaking to linear order, we show how the topological-amplitude decomposition can be mapped onto the standard expansion using reduced amplitudes characterized by S U (3 ) representations. The tree and annihilation amplitudes can be calculated in factorization up to corrections which are quadratic in the color-counting parameter 1 /Nc. We find new sum rules connecting D+→KSK+ , Ds+→KSπ+, and D+→K+π0, which test the quality of the 1 /Nc expansion. Subsequently, we determine the topological amplitudes in a global fit to the data, taking the statistical correlations among the various measurements into account. We carry out likelihood ratio tests in order to quantify the role of specific topological contributions. While the S U (3 )F limit is excluded with a significance of more than 5 standard deviations, a good fit (with Δ χ2<1 ) can be obtained with less than 28% of S U (3 )F breaking in the decay amplitudes. The magnitude of the penguin amplitude Pbreak, which probes the Glashow-Iliopoulos-Maiani mechanism, is consistent with zero; the hypothesis Pbreak=0 is rejected with a significance of just 0.7 σ . We obtain the Standard-Model correlation between B (D0→KLπ0) and B (D0→KSπ0), which probes doubly Cabibbo-suppressed amplitudes, and find that B (D0→KLπ0)

  14. Growth hormone promoted tyrosyl phosphorylation of growth hormone receptors in murine 3T3-F442A fibroblasts and adipocytes

    SciTech Connect

    Foster, C.M.; Shafer, J.A.; Rozsa, F.W.; Wang, X.; Lewis, S.D.; Renken, D.A.; Natale, J.E.; Schwartz, J.; Carter-Su, C.

    1988-01-12

    Because many growth factor receptors are ligand-activated tyrosine protein kinases, the possibility that growth hormone (GH), a hormone implicated in human growth, promotes tyrosyl phosphorylation of its receptor was investigated. /sup 125/I-Labeled human GH was covalently cross-linked to receptors in intact 3T3-F442A fibroblasts, a cell line which differentiates into adipocytes in response to GH. The cross-linked cells were solubilized and passed over a column of phosphotyrosyl binding antibody immobilized on protein A-Sepharose. Immunoadsorbed proteins were eluted with a hapten (p-nitrophenyl phosphate) and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The eluate from the antibody column contained in M/sub r/ 134,000 /sup 125/I-GH-receptor complex. A similar result was obtained when the adipocyte form of 3T3-F442A cells was used in place of fibroblast form. O-Phosphotyrosine prevented /sup 125/I-GH-receptor complexes from binding to the antibody column, whereas O-phosphoserine and O-phosphothreonine did not. In studies of GH-promoted phosphorylation in 3T3-F442A fibroblasts labeled metabolically with (/sup 32/P)P/sub i/, GH was shown to stimulate formation of a /sup 32/P-labeled protein which bound to immobilized phosphotyrosyl binding antibodies. The molecular weight of 114,000 obtained for this protein is similar to that expected for non-cross-linked GH receptor. These observations provide strong evidence that binding of GH to its receptor stimulates phosphorylation of tyrosyl residues in the GH receptor.

  15. Thermoluminescence and photoluminescence study of KY3F10:Ho3+ commercial phosphor powder

    NASA Astrophysics Data System (ADS)

    Debelo, N. G.; Dejene, F. B.; Roro, Kittessa

    2016-06-01

    Thermoluminescence (TL) and photoluminescence (PL) properties of KY3F10:Ho3+ phosphor powder is reported. The TL measurements were carried out for different heating rates and for various durations of UV exposure. The TL intensity increases with the duration of UV exposure up to 20 min and then decreases. A decrease of the glow peak height was observed for the glow curves with an increasing heating rate. The area under the TL-time plot is calculated for each heating rate at a constant UV dose and it is found to be constant and independent of the heating rate. It is found that the observed decrement in intensity of each glow curve following an increment in the heating rate is not attributed to the thermal quenching effect. Important TL kinetic parameters namely, the activation energy (E) and the frequency factor (s) were calculated using a variable heating rate (VHR) method. The glow peaks obey first order kinetics. PL emission spectra were also investigated at four main excitation wavelengths; namely, 362, 416, 454 and 486 nm. Green emission at 540 nm and faint red emission at 750 nm were observed for all the excitations. The green emission at 540 nm is ascribed to the 5F4–5I8 and 5S2–5I8 transitions and the faint red emission at 750 nm is due to the 5F4–5I7 and 5S2–5I7 transitions. In addition to the sharp green emission at 540 nm, a broad emission centered at 600 nm was observed for excitation wavelength of 362 nm.

  16. Plexin A3 is involved in semaphorin 3F-mediated oligodendrocyte precursor cell migration.

    PubMed

    Xiang, Xin; Zhang, Xuan; Huang, Qi-Lin

    2012-11-21

    Class 3 semaphorins are expressed in the neurodevelopmental or damage repair phase of the central nervous system (CNS). They play an important role in guiding axon growth and directing cell migration, including the migration of oligodendrocyte precursor cells (OPCs). As co-receptors for semaphorin 3F(sema3F), the expression and role of neuropilin-2 (NRP2) and plexin A3 in OPC migration are unclear. Using RT-PCR, Western blot analysis, and immunofluorescence, we demonstrated that primary OPCs and immature oligodendrocytes from neonatal rats express NRP2 and plexin A3. After transfection with NRP2 siRNA and plexin A3 siRNA, the number of migrating OPCs attracted to sema3F remarkably decreased. These results suggest that plexin A3 is expressed in OPCs and immature oligodendrocytes and is involved in OPC migration. PMID:23063687

  17. Time-resolved luminescence spectroscopy of structurally disordered K3WO3F3 crystals

    NASA Astrophysics Data System (ADS)

    Omelkov, S. I.; Spassky, D. A.; Pustovarov, V. A.; Kozlov, A. V.; Isaenko, L. I.

    2016-08-01

    Three emission centers of exciton-like origin, with distinct relaxation time, emission and excitation spectra were revealed in K3WO3F3 and described taking into account its structural disordering. Low-temperature monoclinic phase of K3WO3F3 features few anion sites with mixed oxygen/fluorine occupancy per [WO3F3] octahedron. Therefore, different kinds of distorted octahedra form, providing different luminescence centers. The time-resolved luminescence spectroscopy technique was applied to distinguish these centers. The simultaneous thermal quenching of them above ∼200 K was qualitatively explained involving dynamic structural disorder of the compound. The energy transfer mechanism between centers was found and tentatively described by the diffusion of excitons. Apart from intrinsic luminescence, the PL of defect-related centers was discovered and the role of shallow charge carrier traps in the low-temperature persistent luminescence was revealed.

  18. Hypoxia induces tumor and endothelial cell migration in a semaphorin 3F- and VEGF-dependent manner via transcriptional repression of their common receptor neuropilin 2.

    PubMed

    Coma, Silvia; Shimizu, Akio; Klagsbrun, Michael

    2011-01-01

    Neuropilin-2 (NRP2) is a receptor expressed by tumor cells and endothelial cells (EC) that binds both semaphorin 3F (SEMA3F), a potent inhibitor of tumor angiogenesis and metastasis, and vascular endothelial growth factor (VEGF), a potent stimulator of tumor angiogenesis. It was found that glioblastoma and melanoma cells repressed NRP2 expression when maintained under hypoxic conditions and after treatment with the hypoxia-mimetic agent desferrioxamine (DFO), at both the mRNA and protein levels. Silencing of HIF1-α, the hypoxia-induced subunit of the hypoxia inducible factor (HIF), abrogated DFO-induced NRP2 repression. Conversely, ectopic expression of HIF1-α directly repressed NRP2 promoter activity and expression. NRP2 is the sole receptor for SEMA3F. Loss of NRP2 expression in tumor cells inhibited SEMA3F-dependent activities, such as inactivation of RhoA, depolymerization of F-actin, and inhibition of tumor cell migration. On the other hand, loss of NRP2 expression in tumor cells increased VEGF protein levels in conditioned media, with no effects on VEGF mRNA levels. This increase in VEGF protein levels promoted paracrine activation of EC, including VEGF receptor-2 phosphorylation, and activation of downstream signaling proteins such as p44/42 MAPK and p38 MAPK. In addition, the elevated VEGF levels induced EC migration and sprouting, two key steps of tumor angiogenesis in vivo. It was concluded that hypoxia regulates VEGF and SEMA3F activities through transcriptional repression of their common receptor NRP2, providing a novel mechanism by which hypoxia induces tumor angiogenesis, growth and metastasis. PMID:21610314

  19. Neuropilin-2/Semaphorin-3F-mediated repulsion promotes inner hair cell innervation by spiral ganglion neurons

    PubMed Central

    Coate, Thomas M; Spita, Nathalie A; Zhang, Kaidi D; Isgrig, Kevin T; Kelley, Matthew W

    2015-01-01

    Auditory function is dependent on the formation of specific innervation patterns between mechanosensory hair cells (HCs) and afferent spiral ganglion neurons (SGNs). In particular, type I SGNs must precisely connect with inner HCs (IHCs) while avoiding connections with nearby outer HCs (OHCs). The factors that mediate these patterning events are largely unknown. Using sparse-labeling and time-lapse imaging, we visualized for the first time the behaviors of developing SGNs including active retraction of processes from OHCs, suggesting that some type I SGNs contact OHCs before forming synapses with IHCs. In addition, we demonstrate that expression of Semaphorin-3F in the OHC region inhibits type I SGN process extension by activating Neuropilin-2 receptors expressed on SGNs. These results suggest a model in which cochlear innervation patterns by type I SGNs are determined, at least in part, through a Semaphorin-3F-mediated inhibitory signal that impedes processes from extending beyond the IHC region. DOI: http://dx.doi.org/10.7554/eLife.07830.001 PMID:26302206

  20. Oscillator detector

    SciTech Connect

    Potter, B.M.

    1980-05-13

    An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.

  1. Grid oscillators

    NASA Technical Reports Server (NTRS)

    Popovic, Zorana B.; Kim, Moonil; Rutledge, David B.

    1988-01-01

    Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

  2. Census of Population and Housing, 1980: Summary Tape File 3F. Technical Documentation.

    ERIC Educational Resources Information Center

    Bureau of the Census (DOC), Washington, DC. Data User Services Div.

    This report provides technical documentation associated with a 1980 Census of Population and Housing Summary Tape File (STF) 3F--which contains responses to the extended questionnaire summarized in STF 3, aggregated by school district. The file contains sample data inflated to represent the total population, 100% counts, and unweighted sample…

  3. 1.92 Angstrom Zinc-Free APOBEC3F Catalytic Domain Crystal Structure.

    PubMed

    Shaban, Nadine M; Shi, Ke; Li, Ming; Aihara, Hideki; Harris, Reuben S

    2016-06-01

    The APOBEC3 family of DNA cytosine deaminases is capable of restricting the replication of HIV-1 and other pathogens. Here, we report a 1.92 Å resolution crystal structure of the Vif-binding and catalytic domain of APOBEC3F (A3F). This structure is distinct from the previously published APOBEC and phylogenetically related deaminase structures, as it is the first without zinc in the active site. We determined an additional structure containing zinc in the same crystal form that allows direct comparison with the zinc-free structure. In the absence of zinc, the conserved active site residues that normally participate in zinc coordination show unique conformations, including a 90 degree rotation of His249 and disulfide bond formation between Cys280 and Cys283. We found that zinc coordination is influenced by pH, and treating the protein at low pH in crystallization buffer is sufficient to remove zinc. Zinc coordination and catalytic activity are reconstituted with the addition of zinc only in a reduced environment likely due to the two active site cysteines readily forming a disulfide bond when not coordinating zinc. We show that the enzyme is active in the presence of zinc and cobalt but not with other divalent metals. These results unexpectedly demonstrate that zinc is not required for the structural integrity of A3F and suggest that metal coordination may be a strategy for regulating the activity of A3F and related deaminases. PMID:27139641

  4. IN VITRO PERCUTANEOUS APPROACH OF SODIUM ARSENATE IN B6C3F1 MICE

    EPA Science Inventory

    Percutaneous absorption of sodium [73As] arsenate in female B6C3F1 mice was investigated in this study from various exposure conditions, including solid compound, aqueous solution (100 and 250 ul) and soil (= 23 mg/cm2). In vitro diffusion experiments were conducted for 24 hr usi...

  5. 48 CFR 47.305-3 - F.o.b. origin solicitations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false F.o.b. origin... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-3 F.o.b. origin solicitations. When preparing f.o.b. origin solicitations, the contracting officer shall refer to 47.303, where...

  6. 48 CFR 47.303-3 - F.o.b. origin, freight allowed.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) An allowance for freight... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-3 F.o.b. origin,...

  7. 48 CFR 47.305-3 - F.o.b. origin solicitations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... result in f.o.b. origin contracts shall also contain requirements, information, provisions, and clauses... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false F.o.b. origin... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-3 F.o.b. origin...

  8. 48 CFR 47.303-3 - F.o.b. origin, freight allowed.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) An allowance for freight... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-3 F.o.b. origin,...

  9. 48 CFR 47.303-3 - F.o.b. origin, freight allowed.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) An allowance for freight... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-3 F.o.b. origin,...

  10. 48 CFR 47.305-3 - F.o.b. origin solicitations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false F.o.b. origin... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-3 F.o.b. origin solicitations. When preparing f.o.b. origin solicitations, the contracting officer shall refer to 47.303, where...

  11. 48 CFR 47.305-3 - F.o.b. origin solicitations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false F.o.b. origin... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-3 F.o.b. origin solicitations. When preparing f.o.b. origin solicitations, the contracting officer shall refer to 47.303, where...

  12. 48 CFR 47.305-3 - F.o.b. origin solicitations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false F.o.b. origin... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-3 F.o.b. origin solicitations. When preparing f.o.b. origin solicitations, the contracting officer shall refer to 47.303, where...

  13. 48 CFR 47.303-3 - F.o.b. origin, freight allowed.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) An allowance for freight... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-3 F.o.b. origin,...

  14. Shock wave study of the thermal dissociations of C3F6 and c-C3F6. II. dissociation of hexafluorocyclopropane and dimerization of CF2.

    PubMed

    Cobos, C J; Sölter, L; Tellbach, E; Troe, J

    2014-07-10

    The thermal dissociation of c-C3F6 has been studied in shock waves over the range 620-1030 K monitoring the UV absorption of CF2. The reaction was studied close to its high-pressure limit, but some high-temperature falloff was accounted for. Quantum-chemical and kinetic modeling rationalized the experimental data. The reaction is suggested to involve the 1,3 biradical CF2CF2CF2 intermediate. CF2 formed by the dissociation of c-C3F6 dimerizes to C2F4. The measured rate of this reaction is also found to correspond to the falloff range. Rate constants for 2CF2 → C2F4 as a function of temperature and bath gas concentration [Ar] are given and shown to be consistent with literature values for the high-pressure rate constants from experiments at lower temperatures and dissociation rate constants obtained in the falloff range at higher temperatures. The onset of falloff at intermediate temperatures is analyzed. PMID:24905207

  15. Attenuation of free spheroidal oscillations of the Earth after the M = 9 Earthquake in Sumatra and the super-deep Earthquake in the Sea of Okhotsk: I. the Admissible Q-factor range for the fundamental mode and overtones of the free spheroidal oscillations

    NASA Astrophysics Data System (ADS)

    Molodenskii, S. M.; Molodenskaya, M. S.

    2015-11-01

    The problem of reconstructing the depth distribution of density and the depth and frequency dependences of the mechanical Q-factor in the Earth's mantle from the entire set of the present-day seismic and astrometric data on the travel times and periods of seismic waves and the amplitudes and phases of forced nutations is considered. The solution of the problem is refined by including the new data about the attenuation of the free oscillations of the Earth excited by the Sumatra earthquake ( M = 9) and super-deep earthquake in the Sea of Okhotsk. The actual accuracy of the Q-factor is studied in the first part of the paper. To this end, we analyze (1) the convergence of the Q-factor estimated from the time series of different length shifted along the time axis and (2) the convergence of the results based on the different data. Since the accuracy of identifying all the periods and attenuation factors for the free oscillations from the Sumatra earthquake is significantly higher than for the earthquake with M = 9 in Japan, the data are only compared for the Sumatra and Okhotsk events. The signal-to-noise ratio (SNR) is analyzed based on the records from different Global Seismographic Network (GSN) stations including the station in Obninsk, the Kurchatov station in Kazakhstan, and the main ERM and MAJO stations in Japan. It is found that the highest SNR was observed in Obninsk. The inverse problem of reconstructing the density and Q-factor is solved for the frequency dependent real parts of the shear moduli with allowance for the most accurate data about the attenuation factors for the fundamental spheroidal modes of the free oscillations of the Earth.

  16. Oscillating Permanent Magnets.

    ERIC Educational Resources Information Center

    Michaelis, M. M.; Haines, C. M.

    1989-01-01

    Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)

  17. Dependence of kink oscillation damping on the amplitude

    NASA Astrophysics Data System (ADS)

    Goddard, C. R.; Nakariakov, V. M.

    2016-05-01

    Context. Kink oscillations of coronal loops are one of the most intensively studied oscillatory phenomena in the solar corona. In the large-amplitude rapidly damped regime, these oscillations are observed to have a low quality factor with only a few cycles of oscillation detected before they are damped. The specific mechanism responsible for rapid damping is commonly accepted to be associated with the linear coupling between collective kink oscillations and localised torsional oscillations, the phenomenon of resonant absorption of the kink mode. The role of finite amplitude effects, however, is still not clear. Aims: We investigated the empirical dependence of the kink oscillation damping time and its quality factor, which is defined as the ratio of damping time to oscillation period, on the oscillation amplitude. Methods: We analysed decaying kink oscillation events detected previously with TRACE, SDO/AIA and and STEREO/EUVI in the extreme ultraviolet (EUV) 171 Å band. Results: We found that the ratio of the kink oscillation damping time to the oscillation period systematically decreases with the oscillation amplitude. We approximated the quality factor dependence on the oscillation displacement amplitude via the power-law dependence with the exponent of -1/2, however we stress that this is a by-eye estimate, and a more rigorous estimation of the scaling law requires more accurate measurements and increased statistics. We conclude that damping of kink oscillations of coronal loops depends on the oscillation amplitude, indicating the possible role of non-linear mechanisms for damping.

  18. ATRX immunostaining predicts IDH and H3F3A status in gliomas.

    PubMed

    Ebrahimi, Azadeh; Skardelly, Marco; Bonzheim, Irina; Ott, Ines; Mühleisen, Helmut; Eckert, Franziska; Tabatabai, Ghazaleh; Schittenhelm, Jens

    2016-01-01

    Gliomas are the most frequent intraaxial CNS neoplasms with a heterogeneous molecular background. Recent studies on diffuse gliomas have shown frequent alterations in the genes involved in chromatin remodelling pathways such as α-thalassemia/mental-retardation-syndrome-X-linked gene (ATRX). Yet, the reliability of ATRX in predicting isocitrate dehydrogenase (IDH) and H3 histone, family 3A (H3F3A) mutations in gliomas, is unclear.We analysed the ATRX expression status by immunohistochemistry, in a large series of 1064 gliomas and analysed the results in correlation to IDH, H3F3A and loss of heterozygosity (LOH) 1p/19q status in these tumors. We also investigated the prognostic potential of ATRX concerning the clinical outcome of patients with diffuse gliomas.According to our results, loss of nuclear ATRX expression was accompanied with an astrocytic tumor lineage and a younger age of onset. ATRX loss in astrocytomas was also strongly associated with IDH1/2 and H3F3A mutation (p < 0.0001). Among 196 glial tumors with nuclear ATRX loss, 173 (89 %) had an IDH1 or IDH2 mutation. Among the remaining 23 cases (11 %) with ATRX loss and IDH wild type status, 7 cases had a H3F3A G34R mutation (3 %) and 2 cases had a H3F3A K27M mutation (1 %). ATRX retention in IDH1/2 mutant tumors was strongly associated with LOH 1p/19q and oligodendroglioma histology (p < 0.0001). We also confirmed the significant prognostic role of ATRX. Diffuse gliomas with ATRX loss (n = 137, median 1413 days, 95 % CI: 1065-1860 days) revealed a significantly better clinical outcome compared with tumors with ATRX retention (n = 335, median: 609, 95 % CI: 539-760 days, HR = 1.81, p < 0.0001).In conclusion, ATRX is a potential marker for prediction of IDH/H3F3A mutations and substratification of diffuse gliomas into survival relevant tumor groups. Such classification is of great importance for further clinical decision making especially concerning the therapeutic options

  19. Oscillation quenching mechanisms: Amplitude vs. oscillation death

    NASA Astrophysics Data System (ADS)

    Koseska, Aneta; Volkov, Evgeny; Kurths, Jürgen

    2013-10-01

    Oscillation quenching constitutes a fundamental emergent phenomenon in systems of coupled nonlinear oscillators. Its importance for various natural and man-made systems, ranging from climate, lasers, chemistry and a wide range of biological oscillators can be projected from two main aspects: (i) suppression of oscillations as a regulator of certain pathological cases and (ii) a general control mechanism for technical systems. We distinguish two structurally distinct oscillation quenching types: oscillation (OD) and amplitude death (AD) phenomena. In this review we aim to set clear boundaries between these two very different oscillation quenching manifestations and demonstrate the importance for their correct identification from the aspect of theory as well as of applications. Moreover, we pay special attention to the physiological interpretation of OD and AD in a large class of biological systems, further underlying their different properties. Several open issues and challenges that await further resolving are also highlighted.

  20. Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber

    SciTech Connect

    Amole, C.; Ardid, M.; Asner, David M.; Baxter, D.; Behnke, E.; Bhattacharjee, P. S.; Borsodi, H.; Bou-Cabo, M.; Brice, S. J.; Broemmelsiek, D.; Clark, K.; Collar, J. I.; Cooper, P. S.; Crisler, M.; Dahl, C. E.; Daley, S.; Das, Madhusmita; Debris, F.; Dhungana, N.; Farine, J.; Felis, I.; Filgas, R.; Fines-Neuschild, M.; Girard, Francoise; Giroux, G.; Hai, M.; Hall, Jeter C.; Harris, O.; Jackson, C. M.; Jin, M.; Krauss, C. B.; Lafreniere, M.; Laurin, M.; Lawson, I.; Levine, I.; Lippincott, W. H.; Mann, E.; Martin, J. P.; Maurya, D.; Mitra, Pitam; Neilson, R.; Noble, A. J.; Plante, A.; Podviianiuk, R. B.; Priya, S.; Robinson, A. E.; Ruschman, M.; Scallon, O.; Seth, S.; Sonnenschein, Andrew; Starinski, N.; Stekl, I.; Vazquez-Jauregui, E.; Wells, J.; Wichoski, U.; Zacek, V.; Zhang, J.

    2015-06-12

    New data are reported from the operation of a 2-liter C3F8 bubble chamber in the 2100 meter deep SNOLAB underground laboratory, with a total exposure of 211.5 kg-days at four different recoil energy thresholds ranging from 3.2 keV to 8.1 keV. These data show that C3F8 provides excellent electron recoil and alpha rejection capabilities at very low thresholds, including the rst observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with signicant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.

  1. 'Pseudo-proper' ferroelectric phase transitions in oxyfluoride K3WO3F3

    NASA Astrophysics Data System (ADS)

    Ivliev, M. P.; Misyul, S. V.; Molokeev, M. S.; Sakhnenko, V. P.

    2014-06-01

    Based on the structural data on the phases of cryolite (ordered perovskite) K3WO3F3, we develop a statistical model, which allows to describe the sequence of phase transitions observed in this compound using a unified approach. According to the model, the crystal possesses two structural subsystems: the K cations located in the octahedral positions and the WO3F3 octahedra in positions alternating with K cations. In the symmetric (cubic) phase, each subsystem can be found in one of the eight states. At decreasing temperature, an orientational phase transition in the subsystem of octahedra occurs first, followed by a phase transition to the low-temperature phase, caused by the loss of stability with respect to the ordering in the K cation subsystem. We find that the electric polarization occurs as pseudoproper and discuss the mechanisms of formation of the phase states.

  2. Dual Species NMR Oscillator

    NASA Astrophysics Data System (ADS)

    Weber, Joshua; Korver, Anna; Thrasher, Daniel; Walker, Thad

    2016-05-01

    We present progress towards a dual species nuclear magnetic oscillator using synchronous spin exchange optical pumping. By applying the bias field as a sequence of alkali 2 π pulses, we generate alkali polarization transverse to the bias field. The alkali polarization is then modulated at the noble gas resonance so that through spin exchange collisions the noble gas becomes polarized. This novel method of NMR suppresses the alkali field frequency shift by at least a factor of 2500 as compared to longitudinal NMR. We will present details of the apparatus and measurements of dual species co-magnetometry using this method. Research supported by the NSF and Northrop-Grumman Corp.

  3. Collisional narrowing in the optically pumped CH3OH and CH3F lasers

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.; Koepf, G. A.

    1982-01-01

    The gain linewidth of the optically pumped CH3F laser is observed to narrow and rebroaden with the addition of He. In addition, the same effect is observed in the CH3OH laser with the addition of the polyatomic buffer gases SF6 and CS2. These results offer conclusive evidence of the Dicke narrowing phenomena in these inverted pure rotational transitions. The effect is observed using a high harmonic mixing technique in a Schottky barrier diode.

  4. Studies of carcinogenicity of sodium chlorite in B6C3F1 mice

    SciTech Connect

    Yokose, Y.; Uchida, K.; Nakae, D.; Shiraiwa, K.; Yamamoto, K.; Konishi, Y.

    1987-12-01

    The carcinogenic activities of sodium chlorite in B6C3F1 mice were examined. Sodium chlorite was given at concentration of 0 (control), 0.025% (low dose), or 0.05% (high dose) in the drinking water of 150 female and 150 male mice for 80 weeks, after which time the animals were returned to distilled water without sodium chlorite. All mice were sacrificed 85 weeks from the beginning of the experiment. The incidence of tumor-bearing animals was 32% (control), 34% (low dose), and 26% (high dose) in female mice, and 46% (control), 57% (low dose), and 53% (high dose) in male mice. The types and incidence of neoplasms that occurred frequently in each group of both sexes were similar to those observed spontaneously in B6C3F1 mice. The incidence of lymphomas/leukemias in the high dose group of females (2%), however, was lower than that in the control group (15%). Furthermore, the incidence of pulmonary adenomas in the high dose group of males (12%) was higher than that in the control group (0%), but neither dose-related increases in the adenoma incidences nor increased incidences of the adenocarcinomas were observed. These results indicated no clear evidence of a carcinogenic potential of sodium chlorite in B6C3F1 mice.

  5. Dark Matter Limits From a 2L C3F8 Filled Bubble Chamber

    SciTech Connect

    Robinson, Alan Edward

    2015-12-01

    The PICO-2L C3F8 bubble chamber search forWeakly Interacting Massive Particle (WIMP) dark matter was operated in the SNOLAB underground laboratory at the same location as the previous CF3I lled COUPP-4kg detector. Neutron calibrations using photoneutron sources in C3F8 and CF3I lled calibration bubble chambers were performed to verify the sensitivity of these target uids to dark matter scattering. This data was combined with similar measurements using a low-energy neutron beam at the University of Montreal and in situ calibrations of the PICO-2L and COUPP-4kg detectors. C3F8 provides much greater sensitivity to WIMP-proton scattering than CF3I in bubble chamber detectors. PICO-2L searched for dark matter recoils with energy thresholds below 10 keV. Radiopurity assays of detector materials were performed and the expected neutron recoil background was evaluated to be 1.6+0:3

  6. Growth, structure and optical properties of nonlinear optical crystal BaZnBO3F

    NASA Astrophysics Data System (ADS)

    Xia, Mingjun; Li, R. K.

    2016-01-01

    Nonlinear optical (NLO) crystal BaZnBO3F (BZBF) with the size of about 20×20×0.5 mm3 is obtained from BaF2-NaF flux, and single crystal X-ray diffraction reveals that it belongs to space group P 6 ̅ with cell parameters of a=5.1045(6) Å, c=4.3116(10) Å and Z=1. In the structure of BZBF, the BO3 planar triangles are interconnected through O atoms from ZnO3F2 trigonal bipyramid to form (Zn3B3O6F6) twelve-membered rings (12-MRs), then the layers which are built with condensation from 12-MRs at ab plane, are further linked by the apical F from ZnO3F2 to form three dimensional framework along the c direction. The title crystal exhibits high transmittance in the range of 300-3000 nm with a UV transmission cutoff at 223 nm according to transmission spectra. Powder SHG tests indicate that the effective NLO coefficient of BZBF crystal is about 2.8 times that of KH2PO4 (KDP) crystal due to perfect alignment of the BO3 groups.

  7. Dark matter limits from a 2L C3F8 filled bubble chamber

    NASA Astrophysics Data System (ADS)

    Robinson, Alan Edward

    The PICO-2L C3F8 bubble chamber search for Weakly Interacting Massive Particle (WIMP) dark matter was operated in the SNOLAB underground laboratory at the same location as the previous CF3I filled COUPP-4kg detector. Neutron calibrations using photoneutron sources in C3F8 and CF3I filled calibration bubble chambers were performed to verify the sensitivity of these target fluids to dark matter scattering. This data was combined with similar measurements using a low-energy neutron beam at the University of Montreal and in situ calibrations of the PICO-2L and COUPP-4kg detectors. C3F 8 provides much greater sensitivity to WIMP-proton scattering than CF 3I in bubble chamber detectors. PICO-2L searched for dark matter recoils with energy thresholds below 10 keV. Radiopurity assays of detector materials were performed and the expected neutron recoil background was evaluated to be 1.6 +0.3-0.9 single bubble events during the 211.5 kg-day exposure. Twelve single bubble dark matter candidate events were observed. These events were not uniformly distributed in time, and were likely caused by particulates in the active volume. Despite this background, PICO-2L sets a world-leading upper limit to the WIMP-proton spin dependent scattering cross-section.

  8. Nasal Tumorigenesis in B6C3F1 Mice Following Intraperitoneal Diethylnitrosamine.

    PubMed

    Chen, Yung-Ju; Wallig, Matthew A; Jeffery, Elizabeth H

    2016-08-01

    Diethylnitrosamine (DEN) is a chemical broadly used in animal models as a hepatocarcinogen, reported to also cause pulmonary neoplasms in mice. The original objective was to evaluate the impact of a Western diet with or without 10% broccoli on DEN-induced on liver cancer. We administered DEN (45 mg/kg) intraperitoneally to young adult male B6C3F1 mice by 6 weekly injections and evaluated liver cancer 6 months after the DEN treatments. Here, we report unexpected primary tumorigenesis in nasal epithelium, independent of dietary treatment. More than 50% of DEN-treated B6C3F1 mice developed nasal neoplasm-related lesions, not reported previously in the literature. Only one of these neoplasms was visible externally prior to postmortem examination. Intraperitoneal DEN treatment used as a model for liver cancer can have a carcinogenic effect on the nasal epithelium in B6C3F1 mice, which should be carefully monitored in future liver cancer studies. PMID:27207684

  9. Semaphorin-3F functions as a tumor suppressor in colorectal cancer due to regulation by DNA methylation

    PubMed Central

    Gao, Xuesong; Tang, Chong; Shi, Wen; Feng, Shichun; Qin, Weiyan; Jiang, Tian; Sun, Yongqiang

    2015-01-01

    Semaphorin-3F (SEMA3F) is a member of the class III semaphorin family, and is seen as a candidate tumor suppressor gene. The aims of this study were to evaluate the effect of SEMA3F in colorectal cancer (CRC) patients, and to explore the mechanism for that SEMA3F suppresses tumor progression and metastasis. The expression levels of SEMA3F in the colorectal cancer tissues and corresponding non-tumor colorectal tissues were determined by Western blotting and real-time quantitative PCR (qRT-PCR). In addition, we evaluate the effects of SEMA3F on CRC cell migration and colony formation in vitro. Subsequently, quantitative methylation-specific PCR (qMSP) was used to detect the DNA methylation status in the CpG islands of SEMA3F gene promoter in normal colon and colorectal cancer cell lines, colorectal cancer tissues and corresponding non-tumor colorectal tissues. We found that SEMA3F was downregulated in the protein (P < 0.01) and mRNA (P < 0.001) levels in CRC tissues as compared to matched adjacent non-tumor tissues. Moreover, MSP assay showed high levels of SEMA3F gene promoter methylation in the CpG islands in some CRC cell lines and tissue samples. Furthermore, SEMA3F expression was reactivated in CRC cell lines after treatment with 5-Aza-CdR, demethylation of SW620 cells resulted in cell colony formation and invasion inhibition. These findings suggest DNA methylation of promoter CpG island-mediated silencing of the tumor suppressor SEMA3F gene plays an important role in the carcinogenesis of CRC. PMID:26722466

  10. Simple Optoelectronic Feedback in Microwave Oscillators

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Iltchenko, Vladimir

    2009-01-01

    A proposed method of stabilizing microwave and millimeter-wave oscillators calls for the use of feedback in optoelectronic delay lines characterized by high values of the resonance quality factor (Q). The method would extend the applicability of optoelectronic feedback beyond the previously reported class of optoelectronic oscillators that comprise two-port electronic amplifiers in closed loops with high-Q feedback circuits.

  11. Recent progress in opto-electronic oscillator

    NASA Technical Reports Server (NTRS)

    Maleki, Lute

    2005-01-01

    The optoelectronic oscillator (OEO) is a unique device based on photonics techniques to generate highly spectrally pure microwave signals [1]. The development of the OEO was motivated by the need for high performance oscillators in the frequency range larger than 10 GHz, where conventional electronic oscillators have a number of limitations. These limitations typically stem from the product of fQ, where f is the oscillator frequency and Q is the quality factor of the resonator in the oscillator. In conventional resonators, whether electromagnetic or piezoelectric, this product is usually a constant. Thus, as the oscillator frequency is pushed higher, the quality factor degrades, resulting in degradation of the phase noise of the oscillator. An approach to mitigate the problem is to start with a very high quality signal in the 5 to 100 MHz range generated by a quartz oscillator and multiply the frequency to achieve the desired microwave signal. Here again, frequency multiplication also results in an increase of the phase noise by a factor of 2010gN, where N is the multiplication factor.

  12. The axon guidance molecule semaphorin 3F is a negative regulator of tumor progression and proliferation in ileal neuroendocrine tumors

    PubMed Central

    Vercherat, Cécile; Blanc, Martine; Lepinasse, Florian; Gadot, Nicolas; Couderc, Christophe; Poncet, Gilles; Walter, Thomas; Joly, Marie-Odile; Hervieu, Valérie; Scoazec, Jean-Yves; Roche, Colette

    2015-01-01

    Gastro-intestinal neuroendocrine tumors (GI-NETs) are rare neoplasms, frequently metastatic, raising difficult clinical and therapeutic challenges due to a poor knowledge of their biology. As neuroendocrine cells express both epithelial and neural cell markers, we studied the possible involvement in GI-NETs of axon guidance molecules, which have been shown to decrease tumor cell proliferation and metastatic dissemination in several tumor types. We focused on the role of Semaphorin 3F (SEMA3F) in ileal NETs, one of the most frequent subtypes of GI-NETs. SEMA3F expression was detected in normal neuroendocrine cells but was lost in most of human primary tumors and all their metastases. SEMA3F loss of expression was associated with promoter gene methylation. After increasing endogenous SEMA3F levels through stable transfection, enteroendocrine cell lines STC-1 and GluTag showed a reduced proliferation rate in vitro. In two different xenograft mouse models, SEMA3F-overexpressing cells exhibited a reduced ability to form tumors and a hampered liver dissemination potential in vivo. This resulted, at least in part, from the inhibition of mTOR and MAPK signaling pathways. This study demonstrates an anti-tumoral role of SEMA3F in ileal NETs. We thus suggest that SEMA3F and/or its cellular signaling pathway could represent a target for ileal NET therapy. PMID:26447612

  13. Small 6q16.1 Deletions Encompassing POU3F2 Cause Susceptibility to Obesity and Variable Developmental Delay with Intellectual Disability.

    PubMed

    Kasher, Paul R; Schertz, Katherine E; Thomas, Megan; Jackson, Adam; Annunziata, Silvia; Ballesta-Martinez, María J; Campeau, Philippe M; Clayton, Peter E; Eaton, Jennifer L; Granata, Tiziana; Guillén-Navarro, Encarna; Hernando, Cristina; Laverriere, Caroline E; Liedén, Agne; Villa-Marcos, Olaya; McEntagart, Meriel; Nordgren, Ann; Pantaleoni, Chiara; Pebrel-Richard, Céline; Sarret, Catherine; Sciacca, Francesca L; Wright, Ronnie; Kerr, Bronwyn; Glasgow, Eric; Banka, Siddharth

    2016-02-01

    Genetic studies of intellectual disability and identification of monogenic causes of obesity in humans have made immense contribution toward the understanding of the brain and control of body mass. The leptin > melanocortin > SIM1 pathway is dysregulated in multiple monogenic human obesity syndromes but its downstream targets are still unknown. In ten individuals from six families, with overlapping 6q16.1 deletions, we describe a disorder of variable developmental delay, intellectual disability, and susceptibility to obesity and hyperphagia. The 6q16.1 deletions segregated with the phenotype in multiplex families and were shown to be de novo in four families, and there was dramatic phenotypic overlap among affected individuals who were independently ascertained without bias from clinical features. Analysis of the deletions revealed a ∼350 kb critical region on chromosome 6q16.1 that encompasses a gene for proneuronal transcription factor POU3F2, which is important for hypothalamic development and function. Using morpholino and mutant zebrafish models, we show that POU3F2 lies downstream of SIM1 and controls oxytocin expression in the hypothalamic neuroendocrine preoptic area. We show that this finding is consistent with the expression patterns of POU3F2 and related genes in the human brain. Our work helps to further delineate the neuro-endocrine control of energy balance/body mass and demonstrates that this molecular pathway is conserved across multiple species. PMID:26833329

  14. Small 6q16.1 Deletions Encompassing POU3F2 Cause Susceptibility to Obesity and Variable Developmental Delay with Intellectual Disability

    PubMed Central

    Kasher, Paul R.; Schertz, Katherine E.; Thomas, Megan; Jackson, Adam; Annunziata, Silvia; Ballesta-Martinez, María J.; Campeau, Philippe M.; Clayton, Peter E.; Eaton, Jennifer L.; Granata, Tiziana; Guillén-Navarro, Encarna; Hernando, Cristina; Laverriere, Caroline E.; Liedén, Agne; Villa-Marcos, Olaya; McEntagart, Meriel; Nordgren, Ann; Pantaleoni, Chiara; Pebrel-Richard, Céline; Sarret, Catherine; Sciacca, Francesca L.; Wright, Ronnie; Kerr, Bronwyn; Glasgow, Eric; Banka, Siddharth

    2016-01-01

    Genetic studies of intellectual disability and identification of monogenic causes of obesity in humans have made immense contribution toward the understanding of the brain and control of body mass. The leptin > melanocortin > SIM1 pathway is dysregulated in multiple monogenic human obesity syndromes but its downstream targets are still unknown. In ten individuals from six families, with overlapping 6q16.1 deletions, we describe a disorder of variable developmental delay, intellectual disability, and susceptibility to obesity and hyperphagia. The 6q16.1 deletions segregated with the phenotype in multiplex families and were shown to be de novo in four families, and there was dramatic phenotypic overlap among affected individuals who were independently ascertained without bias from clinical features. Analysis of the deletions revealed a ∼350 kb critical region on chromosome 6q16.1 that encompasses a gene for proneuronal transcription factor POU3F2, which is important for hypothalamic development and function. Using morpholino and mutant zebrafish models, we show that POU3F2 lies downstream of SIM1 and controls oxytocin expression in the hypothalamic neuroendocrine preoptic area. We show that this finding is consistent with the expression patterns of POU3F2 and related genes in the human brain. Our work helps to further delineate the neuro-endocrine control of energy balance/body mass and demonstrates that this molecular pathway is conserved across multiple species. PMID:26833329

  15. Synchronization of genetic oscillators

    NASA Astrophysics Data System (ADS)

    Zhou, Tianshou; Zhang, Jiajun; Yuan, Zhanjiang; Chen, Luonan

    2008-09-01

    Synchronization of genetic or cellular oscillators is a central topic in understanding the rhythmicity of living organisms at both molecular and cellular levels. Here, we show how a collective rhythm across a population of genetic oscillators through synchronization-induced intercellular communication is achieved, and how an ensemble of independent genetic oscillators is synchronized by a common noisy signaling molecule. Our main purpose is to elucidate various synchronization mechanisms from the viewpoint of dynamics, by investigating the effects of various biologically plausible couplings, several kinds of noise, and external stimuli. To have a comprehensive understanding on the synchronization of genetic oscillators, we consider three classes of genetic oscillators: smooth oscillators (exhibiting sine-like oscillations), relaxation oscillators (displaying jump dynamics), and stochastic oscillators (noise-induced oscillation). For every class, we further study two cases: with intercellular communication (including phase-attractive and repulsive coupling) and without communication between cells. We find that an ensemble of smooth oscillators has different synchronization phenomena from those in the case of relaxation oscillators, where noise plays a different but key role in synchronization. To show differences in synchronization between them, we make comparisons in many aspects. We also show that a population of genetic stochastic oscillators have their own synchronization mechanisms. In addition, we present interesting phenomena, e.g., for relaxation-type stochastic oscillators coupled to a quorum-sensing mechanism, different noise intensities can induce different periodic motions (i.e., inhomogeneous limit cycles).

  16. Determination of CCl 3F and CCl 2F 2 in seawater and air

    NASA Astrophysics Data System (ADS)

    Bullister, J. L.; Weiss, R. F.

    1988-05-01

    An improved analytical technique has been developed for the rapid and accurate shipboard measurement of two anthropogenically produced chlorofluorocarbons (CFCs), CCl 3F (F-11) and CCl 2F 2 (F-12) in air and seawater. Gas samples (dry air or standard) are injected into a stream of purified gas and then concentrated in a low temperature trap. Seawater samples collected in oceanographic Niskin bottles are transferred into glass syringes for storage until analysis. An aliquot of approximately 30 cm 3 of seawater is introduced into a glass stripping chamber where the dissolved gases are purged with purified gas, and the evolved CFCs are concentrated in the same cold trap. The trap is subsequently isolated and heated, and the CFCs are automatically transferred by a stream of carrier gas into a precolumn and then a chromatographic separating column. The CCl 3F and CCl 2F 2 peaks are detected by an electron capture detector (ECD) and their areas are integrated digitally. CFC amounts are calculated using fitted calibration curves, generated by injection of various multiple aliquots of gas standard containing known concentrations of CFCs. Preliminary concentration values for these compounds are printed at the completion of each analysis. Total analysis time for air and water samples is < 10 min, allowing detailed vertical profiles of the concentrations of these compounds in the water column and concentrations in the overlying atmosphere to be determined within a few hours of the completion of a hydrographic station. Typical relative standard deviations for analyses of CCl 3F and CCl 2F 2 in near-surface seawater containing equilibrium levels of these compounds are approximately 1%. Limits of detection for both compounds in 30 cm 3 seawater samples are about 0.005 × 10 -12 mol kg -1.

  17. Franck-Condon factors perturbed by damped harmonic oscillators: Solvent enhanced X {sup 1}A{sub g} ↔ A{sup 1}B{sub 1u} absorption and fluorescence spectra of perylene

    SciTech Connect

    Wang, Chen-Wen; Zhu, Chaoyuan Lin, Sheng-Hsien; Yang, Ling; Yu, Jian-Guo

    2014-08-28

    Damped harmonic oscillators are utilized to calculate Franck-Condon factors within displaced harmonic oscillator approximation. This is practically done by scaling unperturbed Hessian matrix that represents local modes of force constants for molecule in gaseous phase, and then by diagonalizing perturbed Hessian matrix it results in direct modification of Huang–Rhys factors which represent normal modes of solute molecule perturbed by solvent environment. Scaling parameters are empirically introduced for simulating absorption and fluorescence spectra of an isolated solute molecule in solution. The present method is especially useful for simulating vibronic spectra of polycyclic aromatic hydrocarbon molecules in which hydrogen atom vibrations in solution can be scaled equally, namely the same scaling factor being applied to all hydrogen atoms in polycyclic aromatic hydrocarbons. The present method is demonstrated in simulating solvent enhanced X {sup 1}A{sub g} ↔ A{sup 1}B{sub 1u} absorption and fluorescence spectra of perylene (medium-sized polycyclic aromatic hydrocarbon) in benzene solution. It is found that one of six active normal modes v{sub 10} is actually responsible to the solvent enhancement of spectra observed in experiment. Simulations from all functionals (TD) B3LYP, (TD) B3LYP35, (TD) B3LYP50, and (TD) B3LYP100 draw the same conclusion. Hence, the present method is able to adequately reproduce experimental absorption and fluorescence spectra in both gas and solution phases.

  18. eIF3f reduces tumor growth by directly interrupting clusterin with anti-apoptotic property in cancer cells

    PubMed Central

    Lee, Ji-Yeon; Kim, Hyun-Ji; Rho, Seung Bae; Lee, Seung-Hoon

    2016-01-01

    Clusterin is a secretory heterodimeric glycoprotein and the overexpression of secretory clusterin (sCLU) promotes cancer cell proliferation and reduces chemosensitivity. Therefore, sCLU might be an effective target for anticancer therapy. In the current study, we identified eIF3f as a novel CLU-interacting protein and demonstrated its novel function as a CLU inhibitor. The overexpression of eIF3f retarded cancer cell growth significantly and induced apoptosis. In addition, eIF3f interacted with the α-chain (1–227) of sCLU. This interaction blocked modification of psCLU, thereby decreasing the expression and secretion of α/β CLU. Consequently, the overexpression of eIF3f suppressed Akt and ERK signaling and subsequently depleted CLU expression. In addition, eIF3F stabilized p53, which increased the expression of p21 and Bax. Interestingly, the expression of Bax was increased without the activation of p53. eIF3f injected into a xenograft model of human cervical cancer in nude mice markedly inhibited tumor growth. The identification of this novel function of eIF3f as a sCLU inhibitor might open novel avenues for developing improved strategies for CLU-targeted anti-cancer therapies. PMID:26988917

  19. Alterations in rabbit vitreal fine structure following C3F8 injection.

    PubMed

    Panessa-Warren, B; Maisel, J M; Warren, J

    1990-01-01

    This study examines the morphological and histochemical changes in the cortical vitreous of 36 rabbit eyes following C3F8 intravitreal gas injection. Eyes were examined by light microscopy (LM) using a modified cryofixation and cryosectioning technique that prevented the loss of soluble tissue moieties and permitted collagen and proteoglycan histochemistry as well as enzyme digestion with hyaluronidase. LM and scanning electron microscopy (SEM) of cryosectioned normal eyes revealed an elaborate fibrillar matrix extending 100-190 microns from the basal lamina of the retina into the vitreous proper, which seemed to be composed of collagen fibrils intimately associated or wrapped in proteoglycan. Following the full expansion of the C3F8 gas bubble in the vitreous, the cortical fibrillar meshwork was absent from the retinal surface and a dense, collagenous material accumulated in the anterior vitreous, especially between the ciliary processes and over the posterior face of the lens. At 41 days postinjection, the fibrillar matrix was reforming and the vitreal cavity was filled with fluid and numerous fibrillar-mucinous islands. These islands did not form sheets or membranes, nor did they attach to either the posterior or the anterior retinal surface. The cortical fibrillar meshwork had reformed at 61 days' recovery; however, the condensed fibrillar material against the lens and filling the spaces between the ciliary processes had not resorbed. Neither shearing of the cortical gel or fibrillar matrix nor congestion of the anterior vitreous was observed in eyes only partially filled with gas. PMID:2265770

  20. SU (3)F gauge family model and new symmetry breaking scale from FCNC processes

    NASA Astrophysics Data System (ADS)

    Bao, Shou-Shan; Liu, Zhuo; Wu, Yue-Liang

    2016-03-01

    Based on the SU (3)F gauge family symmetry model which was proposed to explain the observed mass and mixing pattern of neutrinos, we investigate the symmetry breaking, the mixing pattern in quark and lepton sectors, and the contribution of the new gauge bosons to some flavour changing neutral currents (FCNC) processes at low energy. With the current data of the mass differences in the neutral pseudo-scalar P0-Pbar0 systems, we find that the SU (3)F symmetry breaking scale can be as low as 300 TeV and the mass of the lightest gauge boson be about 100 TeV. Other FCNC processes, such as the lepton flavour number violation process μ- →e-e+e- and the semi-leptonic rare decay K → π ν bar ν, contain contributions via the new gauge bosons exchanging. With the constrains obtained from P0-Pbar0 system, we estimate that the contribution of the new physics is around 10-16, far below the current experimental bounds.

  1. Extinction of oscillating populations.

    PubMed

    Smith, Naftali R; Meerson, Baruch

    2016-03-01

    Established populations often exhibit oscillations in their sizes that, in the deterministic theory, correspond to a limit cycle in the space of population sizes. If a population is isolated, the intrinsic stochasticity of elemental processes can ultimately bring it to extinction. Here we study extinction of oscillating populations in a stochastic version of the Rosenzweig-MacArthur predator-prey model. To this end we develop a WKB (Wentzel, Kramers and Brillouin) approximation to the master equation, employing the characteristic population size as the large parameter. Similar WKB theories have been developed previously in the context of population extinction from an attracting multipopulation fixed point. We evaluate the extinction rates and find the most probable paths to extinction from the limit cycle by applying Floquet theory to the dynamics of an effective four-dimensional WKB Hamiltonian. We show that the entropic barriers to extinction change in a nonanalytic way as the system passes through the Hopf bifurcation. We also study the subleading pre-exponential factors of the WKB approximation. PMID:27078294

  2. Extinction of oscillating populations

    NASA Astrophysics Data System (ADS)

    Smith, Naftali R.; Meerson, Baruch

    2016-03-01

    Established populations often exhibit oscillations in their sizes that, in the deterministic theory, correspond to a limit cycle in the space of population sizes. If a population is isolated, the intrinsic stochasticity of elemental processes can ultimately bring it to extinction. Here we study extinction of oscillating populations in a stochastic version of the Rosenzweig-MacArthur predator-prey model. To this end we develop a WKB (Wentzel, Kramers and Brillouin) approximation to the master equation, employing the characteristic population size as the large parameter. Similar WKB theories have been developed previously in the context of population extinction from an attracting multipopulation fixed point. We evaluate the extinction rates and find the most probable paths to extinction from the limit cycle by applying Floquet theory to the dynamics of an effective four-dimensional WKB Hamiltonian. We show that the entropic barriers to extinction change in a nonanalytic way as the system passes through the Hopf bifurcation. We also study the subleading pre-exponential factors of the WKB approximation.

  3. Synchronizing redundant power oscillators

    NASA Technical Reports Server (NTRS)

    Jenson, K. J.

    1969-01-01

    Outputs of oscillators are synchronized by summing the power transformer phase voltages, the summed voltages are applied to the frequency determining inductors of the individual voltage-controlled power oscillators. The beat frequency is eliminated when synchronization is achieved.

  4. Saturation in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Roman, Ahmed; Hanna, James

    2015-03-01

    We consider a weakly nonlinear system consisting of a resonantly forced oscillator coupled to an unforced oscillator. It has long been known that, for quadratic nonlinearities and a 2:1 resonance between the oscillators, a perturbative solution of the dynamics exhibits a phenomenon known as saturation. At low forcing, the forced oscillator responds, while the unforced oscillator is quiescent. Above a critical value of the forcing, the forced oscillator's steady-state amplitude reaches a plateau, while that of the unforced oscillator increases without bound. We show that, contrary to established folklore, saturation is not unique to quadratically nonlinear systems. We present conditions on the form of the nonlinear couplings and resonance that lead to saturation. Our results elucidate a mechanism for localization or diversion of energy in systems of coupled oscillators, and suggest new approaches for the control or suppression of vibrations in engineered systems.

  5. Microelectronic oscillator, 2

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1969-01-01

    Microelectronic oscillator uses a bipolar transistor to circumvent the problem of developing suitable inductors for lower frequencies. The oscillator is fabricated by hybrid thin film techniques or by monolithic construction. Discrete microminiature components may also be employed.

  6. Characteristics and nature of the halogen-bonding interactions between CCl3F and ozone: a supermolecular and SAPT study

    NASA Astrophysics Data System (ADS)

    Esrafili, Mehdi D.; Yourdkhani, Sirous; Bahrami, Aidin

    2013-12-01

    The strength and nature of the halogen-bond interactions in CCl3F...O3 complexes were examined by means of ab initio quantum-chemical calculations and symmetry-adapted perturbation theory (SAPT). Our calculations predict a trifurcated C-Cl...O interaction for the global minimum of CCl3F...O3 complex and several local minima, differing slightly in energy, separated by very low barriers. The calculations, which include a rigorous decomposition of the interaction energies, also indicate that the interaction of CCl3F molecule with O3 is characterised by contributions from both electrostatic and dispersion energies, with the contribution of the latter being dominant. The evaluated SAPT interaction energies for the CCl3F...O3 complexes are generally in good agreement with those obtained using the supermolecule CCSD(T) method, suggesting that SAPT is a proper method to study the intermolecular interactions in these complexes.

  7. Sequential arrival and graded secretion of Sema3F by olfactory neuron axons specify map topography at the bulb.

    PubMed

    Takeuchi, Haruki; Inokuchi, Kasumi; Aoki, Mari; Suto, Fumikazu; Tsuboi, Akio; Matsuda, Ikuo; Suzuki, Misao; Aiba, Atsu; Serizawa, Shou; Yoshihara, Yoshihiro; Fujisawa, Hajime; Sakano, Hitoshi

    2010-06-11

    In the mouse olfactory system, the anatomical locations of olfactory sensory neurons (OSNs) roughly correlate with their axonal projection sites along the dorsal-ventral (D-V) axis of the olfactory bulb (OB). Here we report that an axon guidance receptor, Neuropilin-2 (Nrp2), and its repulsive ligand, Semaphorin-3F (Sema3F), are expressed by OSNs in a complementary manner that is important for establishing olfactory map topography. Sema3F is secreted by early-arriving axons of OSNs and is deposited at the anterodorsal OB to repel Nrp2-positive axons that arrive later. Sequential arrival of OSN axons as well as the graded and complementary expression of Nrp2 and Sema3F by OSNs help to form the topographic order along the D-V axis. PMID:20550939

  8. Covariant harmonic oscillators and coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo; Kim, Young S.; Noz, Marilyn E.

    1995-01-01

    It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.

  9. Luminescence properties of Yb:Er:KY3F10 nanophosphor and thermal treatment effects

    NASA Astrophysics Data System (ADS)

    Gomes, Laércio; Linhares, Horácio Marconi da Silva M. D.; Ichikawa, Rodrigo Uchida; Martinez, Luis Gallego; Baldochi, Sonia Licia

    2016-04-01

    In this work, we present the spectroscopic properties of KY3F10 nanocrystals activated with erbium and codoped with ytterbium ions. The most important processes that lead to the erbium upconversion of green and red emissions of Er3+ were identified. A time-resolved luminescence spectroscopy technique was employed to measure the luminescence decays of 4S3/2 and 4F9/2 excited levels of Er3+ and to determine the upconversion processes and the luminescence efficiencies of erbium in the visible. Analysis of the luminescence kinetics in Yb:Er:KY3F10 shows a rapid upconversion (Up1) for the green emission with a time constant of 0.31 μs after pulsed laser excitation at 972 nm for as synthesized nanocrystals, which is faster than the time constant measured for the bulk crystal (23 μs). In addition, it is observed a second upconversion process (non-resonant) (Up2) responsible for the red emission (Er3+), which competes with Up1 process. However, the luminescence efficiency of the green emission (4S3/2) is observed to be very low (1.6%) for the as synthesized nanocrystal (25 °C). Nevertheless, it increases with the nanopowder heat treatment reaching an efficiency of 99% (T = 550 °C) relative to the bulk crystal. Similar luminescence behavior was observed for the 4F9/2 level (Er3+) that emits red emission. X-ray diffraction analysis of nanopowder by Rietveld method reveled that the mean crystallite size remains unchanged (8.3-12.3 nm) after thermal treatments with T ∼ 400 °C, while the 4S3/2 luminescence efficiency strongly increases to 20%. The luminescence dynamics indicates that Er3+ ions distribution plays a determinant role in the luminescence efficiency of green and red emissions of Er3+ besides also the strong influence on the upconversions processes. The observed luminescence effect is caused by the non-uniform Er3+ (and Yb3+) ions distribution due to the nanocrystal grown, which introduces a concentration gradient that increases towards the nanoparticle

  10. SHOCK-EXCITED OSCILLATOR

    DOEpatents

    Creveling, R.

    1957-12-17

    S> A shock-excited quartz crystal oscillator is described. The circuit was specifically designed for application in micro-time measuring work to provide an oscillator which immediately goes into oscillation upon receipt of a trigger pulse and abruptly ceases oscillation when a second pulse is received. To achieve the instant action, the crystal has a prestressing voltage applied across it. A monostable multivibrator receives the on and off trigger pulses and discharges a pulse through the crystal to initiate or terminate oscillation instantly.

  11. Discrete monotron oscillator

    SciTech Connect

    Carlsten, B.E.; Haynes, W.B.

    1996-08-01

    The authors theoretically and numerically investigate the operation and behavior of the discrete monotron oscillator, a novel high-power microwave source. The discrete monotron differs from conventional monotrons and transit time oscillators by shielding the electron beam from the monotron cavity`s RF fields except at two distinct locations. This makes the discrete monotron act more like a klystron than a distributed traveling wave device. As a result, the oscillator has higher efficiency and can operate with higher beam powers than other single cavity oscillators and has more stable operation without requiring a seed input signal than mildly relativistic, intense-beam klystron oscillators.

  12. Nature's Autonomous Oscillators

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.

    2012-01-01

    Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.

  13. Sema3F downregulates p53 expression leading to axonal growth cone collapse in primary hippocampal neurons

    PubMed Central

    Yang, Guanglu; Qu, Xiang; Zhang, Junmei; Zhao, Weidong; Wang, Hua

    2012-01-01

    Hippocampal nerve growth is regulated by the coordinated action of numerous external stimuli, including positively acting neurotrophin-derived growth cues and restrictive semaphorin cues, however the underlying cellular mechanisms remain largely unclear. We examined the potential cellular mechanism of Semaphorin3F (Sema3F) in cultured primary hippocampal neurons. We show that Sema3F can down-regulate p53 expression in primary hippocampal neurons, thereby contributing to growth cone collapse. Sema3F suppressed p53-induced pathways, which we show to be required to maintain growth cone structure. Sema3F-induced growth cone collapse was partially reversed by overexpression of p53, which promoted growth cone extension. Inhibition of p53 function by inhibitor, siRNAs, induced axonal growth cone collapse, whereas p53 over-expression led to larger growth cones in cultured primary hippocampal neurons.These data reveal a novel mechanism by which Sema3F can induce hippocampal neuron growth cone collapse and provide evidence for an intracellular mechanism for cross talk between positive and negative axon growth cues. PMID:22977659

  14. Non-linear oscillations

    NASA Astrophysics Data System (ADS)

    Hagedorn, P.

    The mathematical pendulum is used to provide a survey of free and forced oscillations in damped and undamped systems. This simple model is employed to present illustrations for and comparisons between the various approximation schemes. A summary of the Liapunov stability theory is provided. The first and the second method of Liapunov are explained for autonomous as well as for nonautonomous systems. Here, a basic familiarity with the theory of linear oscillations is assumed. La Salle's theorem about the stability of invariant domains is explained in terms of illustrative examples. Self-excited oscillations are examined, taking into account such oscillations in mechanical and electrical systems, analytical approximation methods for the computation of self-excited oscillations, analytical criteria for the existence of limit cycles, forced oscillations in self-excited systems, and self-excited oscillations in systems with several degrees of freedom. Attention is given to Hamiltonian systems and an introduction to the theory of optimal control is provided.

  15. Nonlinear optical properties ofBaAlBO3F2 crystal.

    PubMed

    Zhou, Yong; Yue, Yinchao; Wang, Jianuo; Yang, Feng; Cheng, Xiankun; Cui, Dafu; Peng, Qinjun; Hu, Zhanggui; Xu, Zuyan

    2009-10-26

    We investigated the nonlinear optical properties of new BaAlBO(3)F(2)(BABF) crystal. The high quality BABF is nonhygroscopic and possesses a moderate birefringence suitable for UV light generation. On the basis of its refractive index dispersion curves, it is inferred that BABF has great potential applications nonlinear optical material, notably for UV light generation at 355 nm. In order to characterize its nonlinear optical properties, BABF samples were cut an oriented in phase matching conditions The optical conversion efficiency from 1064 nm to 532 nm was investigated for the first time: up to 49.0% were achieved. The external angular acceptance bandwidth of SHG and THG for 1064 nm pump light was measured. PMID:19997227

  16. Near Infrared Luminescence Properties of Mn(5+): Ca5(PO4)3F

    NASA Technical Reports Server (NTRS)

    Davis, Valetta R.; Hoemmerich, Uwe; Loutts, George B.

    1997-01-01

    We report a spectroscopic investigation of Mn(5+) doped Ca5(PO4)(sub 3)F or FAP. Mn(5+) doped crystals have recently attracted world wide attention for potential solid-state laser applications. Following optical excitation of Mn: FAP with the 600 nm output of a Nd: YAG OPO laser system, we observed a strong near infrared luminescence centered at around 1150 nm. The room temperature luminescence decay time was measured to be approximately 635 microseconds. We attribute the infrared luminescence to the(1)E yields (3)A2 transition of tetrahedrally coordinated Mn5+ ions located in a strong crystal field environment. Absorption, luminescence and lifetime data of Mn: FAP will be presented and discussed.

  17. Ne matrix spectra of the sym-C6Br3F3+ radical cation

    USGS Publications Warehouse

    Bondybey, V.E.; Sears, T.J.; Miller, T.A.; Vaughn, C.; English, J.H.; Shiley, R.S.

    1981-01-01

    The electronic absorption and laser excited, wavelength resolved fluorescence spectra of the title cation have been observed in solid Ne matrix and vibrationally analysed. The vibrational structure of the excited B2A2??? state shows close similarity to the parent compound. The X2E??? ground state structure is strongly perturbed and irregular owing to a large Jahn-Teller distortion. The data are analysed in terms of a recently developed, sophisticated multimode Jahn-Teller theoretical model. We have generated the sym-C6Br3F3+ cations in solid Ne matrix and obtained their wavelength resolved emission and absorption spectra. T ground electronic X2E??? state exhibits an irregular and strongly perturbed vibrational structure, which can be successfully modeled using sophisticated multimode Jahn-Teller theory. ?? 1981.

  18. Vibrational relaxation of matrix-isolated CH/sub 3/F and HCl

    SciTech Connect

    Young, L.

    1981-08-01

    Kinetic and spectroscopic studies have been performed on CH/sub 3/F and HCl as a function of host matrix and temperature. Temporally and spectrally resolved infrared fluorescence was used to monitor the populations of both the initially excited state and the lower lying levels which participate in the relaxation process. For CH/sub 3/F, relaxation from any of the levels near 3.5 ..mu.., i.e. the CH stretching fundamentals or bend overtones, occurs via rapid (< 5 ns) V ..-->.. V transfer to 2..nu../sub 3/ with subsequent relaxation of the ..nu../sub 3/ (CF stretch) manifold. Lifetimes of 2..nu../sub 3/ and ..nu../sub 3/ were determined through overtone, ..delta..V = 2, and fundamental fluorescence. These lifetimes show a dramatic dependence on host lattice, an increase of two orders of magnitude in going from Xe and Ar matrices. Lifetimes depend only weakly on temperature. The relaxation of 2..nu../sub 3/ and ..nu../sub 3/ is consistent with a model in which production of a highly rotationally excited guest via collisions with the repulsive wall of the host is the rate limiting step. For HCl, lifetimes of v = 1,2,3 have been determined. In all hosts, the relaxation is non-radiative. For a given vibrational state, v, the relaxation rate increases in the series k(Ar) < k(Kr) < k(Xe). The dependence of the relaxation rate; on v is superlinear in all matrices, the deviation from linearity increasng in the order Ar < Kr < Xe. The relaxation rates become more strongly temperature dependent with increasing vibrational excitation. The results are consistent with a mechanism in which complex formation introduces the anisotropy necessary to induce a near resonant V ..-->.. R transition in the rate limiting step.

  19. Min-protein oscillations in round bacteria

    NASA Astrophysics Data System (ADS)

    Huang, Kerwyn Casey; Wingreen, Ned S.

    2004-12-01

    In rod-shaped Escherichia coli cells, the Min proteins, which are involved in division-site selection, oscillate from pole-to-pole. The homologs of the Min proteins from the round bacterium Neisseria gonorrhoeae also form a spatial oscillator when expressed in wild-type and round, rodA- mutants of E. coli, suggesting that the Min proteins form an oscillator in N. gonorrhoeae. Here we report that a numerical model for Min-protein oscillations in rod-shaped cells also produces oscillations in round cells (cocci). Our numerical results explain why the MinE-protein rings found in wild-type E. coli are absent in round mutants. In addition, we find that for round cells there is a minimum radius below which oscillations do not occur, and a maximum radius above which oscillations become mislocalized. Finally, we demonstrate that Min-protein oscillations can select the long axis in nearly round cells based solely on geometry, a potentially important factor in division-plane selection in cocci.

  20. Oscillator Stengths and Their Uncertainties

    NASA Astrophysics Data System (ADS)

    Wahlgren, G. M.

    2010-11-01

    The oscillator strength is a key parameter in the description of the line absorption coefficient. It can be determined through experiment, abinitio and semi-empirical calculations, and backward analysis of line profiles. Each method has its advantages, and the uncertainty attached to its determination can range from low to indeterminable. For analysis of line profiles or equivalent widths the uncertainty in the oscillator strength can rival or surpass the difference between the derived element abundance from classical LTE and non-LTE analyses. It is therefore important to understand the nature of oscillator strength uncertainties and to assess whether this uncertainty can be a factor in choosing to initiate a non-LTE analysis or in the interpretation of its results. Methods for the determination of the oscillator strength are presented, prioritizing experiments, along with commentary about the sources and impact of the uncertainties. The Sei spectrum is used to illustrate how gf-values can be constructed from published data on atomic lifetimes and line intensities.

  1. Rotor-Liquid-Fundament System's Oscillation

    NASA Astrophysics Data System (ADS)

    Kydyrbekuly, A.

    The work is devoted to research of oscillation and sustainability of stationary twirl of vertical flexible static dynamically out-of-balance rotor with cavity partly filled with liquid and set on relative frame fundament. The accounting of such factors like oscillation of fundament, liquid oscillation, influence of asymmetry of installation of a rotor on a shaft, anisotropism of shaft support and fundament, static and dynamic out-of-balance of a rotor, an external friction, an internal friction of a shaft, allows to settle an invoice more precisely kinematic and dynamic characteristics of system.

  2. Paradoxes of neutrino oscillations

    SciTech Connect

    Akhmedov, E. Kh.; Smirnov, A. Yu.

    2009-08-15

    Despite the theory of neutrino oscillations being rather old, some of its basic issues are still being debated in the literature. We discuss a number of such issues, including the relevance of the 'same energy' and 'same momentum' assumptions, the role of quantum-mechanical uncertainty relations in neutrino oscillations, the dependence of the coherence and localization conditions that ensure the observability of neutrino oscillations on neutrino energy and momentum uncertainties, the question of (in)dependence of the oscillation probabilities on the neutrino production and detection processes, and the applicability limits of the stationary-source approximation. We also develop a novel approach to calculation of the oscillation probability in the wave-packet approach, based on the summation/integration conventions different from the standard one, which allows a new insight into the 'same energy' vs. 'same momentum' problem. We also discuss a number of apparently paradoxical features of the theory of neutrino oscillations.

  3. Multichannel applications of double relaxation oscillation SQUIDs

    NASA Astrophysics Data System (ADS)

    Lee, Yong-Ho; Kwon, Hyukchan; Kim, Jin-Mok; Park, Yong-Ki

    2001-12-01

    Double relaxation oscillation SQUIDs (DROSs) provided high flux-to-voltage transfers of larger than 1 mV Φ0-1 and simple flux-locked loop circuits were used for SQUID operation. We constructed two multichannel systems based on DROSs. The first system is a 40-channel planar gradiometer system consisting of integrated first-order pickup coils. average noise level of the 40 channels is 1 fT cm-1 Hz-1/2 at 100 Hz, corresponding to a field noise of 4 fT Hz-1/2, operating inside a magnetically shielded room. The second one is a 37-channel magnetometer system with 37 integrated magnetometers distributed on a spherical surface and measures field component normal to the head surface. The average noise of the magnetometers is 3 fT Hz-1/2 at 100 Hz. The two systems were applied to measure neuromagnetic fields.

  4. Upregulation of estrogen receptor expression in the uterus of ovariectomized B6C3F1 mice and Ishikawa cells treated with bromoethane

    SciTech Connect

    Aoyama, Hiroaki; Couse, John F.; Hewitt, Sylvia C.; Haseman, Joseph K.; He, Hong; Zheng, Xiaolin; Majstoravich, Sonja; Korach, Kenneth S.; Dixon, D. . E-mail: dixon@niehs.nih.gov

    2005-12-15

    In a 2-year NTP bioassay, Bromoethane (BE) was found to induce endometrial neoplasms in the uterus of B6C3F1 mice [; ]. In women, hormonal influences, such as 'unopposed' estrogenic stimulus, have been implicated as important etiologic factors in uterine cancer. BE, however, does not affect the serum concentrations of sex hormones in female B6C3F1 mice [] and the mechanism of BE-induced uterine carcinogenesis still remains unclear. In the present study, we examined the estrogenic effects of BE on the uterus of ovariectomized B6C3F1 mice and on Ishikawa cells. Groups of 6 mice were given daily s.c. injections of 0, 100, 500 or 1000 mg BE/kg for 3 consecutive days. Mice treated with 17{beta}-estradiol served as positive controls. Mice were necropsied 24 h after the final injection, and uteri were weighed and examined histologically and immunohistochemically along with the vagina. Changes observed in the estrogen-treated mice included increased uterine weights, edema and inflammation of the endometrium, increased epithelial layers of the uterine and vaginal lumens and keratinization of the vaginal epithelium. In the BE-treated mice, no such changes occurred; however, immunohistochemical staining of the uterus revealed a significant increase in immunoexpression of the estrogen receptor alpha (ER{alpha}) in the two higher dose groups. Analysis of mRNA also showed slightly increased uterine ER{alpha} expression in these groups. Upregulated expression of ER{alpha} was confirmed in BE-treated Ishikawa cells, in which Western blotting analyses identified an intense signal at approximately 66 kDa, which is consistent with ER{alpha}. These data suggest that upregulated expression of ER{alpha} may be important in the induction of endometrial neoplasms in BE-treated mice.

  5. Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, D. (Editor); Kim, Y. S. (Editor); Zachary, W. W. (Editor)

    1993-01-01

    Proceedings of a workshop on Harmonic Oscillators held at the College Park Campus of the University of Maryland on March 25 - 28, 1992 are presented. The harmonic oscillator formalism is playing an important role in many branches of physics. This is the simplest mathematical device which can connect the basic principle of physics with what is observed in the real world. The harmonic oscillator is the bridge between pure and applied physics.

  6. Boxing with Neutrino Oscillations

    NASA Astrophysics Data System (ADS)

    Wagner, Dj; Weiler, Thomas J.

    1998-03-01

    We have developed a model-independent ``box'' parameterization of neutrino oscillations. Oscillation probabilities are linear in these new parameters, so measurements can straighforwardly determine the box parameters which can then be manipulated to yield magnitudes of mixing matrix elements. We will present these new parameters and examine the effects of unitarity which reduce the number of independent parameters to the minimum set. The framework presented here will facilitate general analyses of neutrino oscillations among n >= 3 flavors.

  7. Self-oscillation

    NASA Astrophysics Data System (ADS)

    Jenkins, Alejandro

    2013-04-01

    Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain dynamical systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy into the vibration: no external rate needs to be adjusted to the resonant frequency. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the swaying of the London Millennium Footbridge in 2000. Clocks are self-oscillators, as are bowed and wind musical instruments. The heart is a “relaxation oscillator”, i.e., a non-sinusoidal self-oscillator whose period is determined by sudden, nonlinear switching at thresholds. We review the general criterion that determines whether a linear system can self-oscillate. We then describe the limiting cycles of the simplest nonlinear self-oscillators, as well as the ability of two or more coupled self-oscillators to become spontaneously synchronized (“entrained”). We characterize the operation of motors as self-oscillation and prove a theorem about their limit efficiency, of which Carnot’s theorem for heat engines appears as a special case. We briefly discuss how self-oscillation applies to servomechanisms, Cepheid variable stars, lasers, and the macroeconomic business cycle, among other applications. Our emphasis throughout is on the energetics of self-oscillation, often neglected by the literature on nonlinear dynamical systems.

  8. Acrylonitrile is a multisite carcinogen in male and female B6C3F1 mice.

    PubMed

    Ghanayem, Burhan I; Nyska, Abraham; Haseman, Joseph K; Bucher, John R

    2002-07-01

    Acrylonitrile is a heavily produced unsaturated nitrile, which is used in the production of synthetic fibers, plastics, resins, and rubber. Acrylonitrile is a multisite carcinogen in rats after exposure via gavage, drinking water, or inhalation. No carcinogenicity studies of acrylonitrile in a second animal species were available. The current studies were designed to assess the carcinogenicity of acrylonitrile in B6C3F1 mice of both sexes. Acrylonitrile was administered by gavage at 0, 2.5, 10, or 20 mg/kg/day, 5 days per week, for 2 years. Urinary thiocyanate and N-acetyl-S-(2-cyanoethyl)-L-cysteine were measured as markers of exposure to acrylonitrile. In general, there were dose-related increases in urinary thiocyanate and N-acetyl-S-(2-cyanoethyl)-L-cysteine concentrations in all dosed groups of mice and at all time points. Survival was significantly (p < 0.001) reduced in the top dose (20 mg/kg) group of male and female mice relative to controls. The incidence of forestomach papillomas and carcinomas was increased in mice of both sexes in association with an increase in forestomach epithelial hyperplasia. The incidence of Harderian gland adenomas and carcinomas was also markedly increased in the acrylonitrile-dosed groups. In female mice, the incidence of benign or malignant granulosa cell tumors (combined) in the ovary in the 10 mg/kg dose group was greater than that in the vehicle control group, but because of a lack of dose response, this was considered an equivocal finding. In addition, the incidences of atrophy and cysts in the ovary of the 10 and 20 mg/kg dose groups were significantly increased. The incidences of alveolar/bronchiolar adenoma or carcinoma (combined) were significantly increased in female mice treated with acrylonitrile at 10 mg/kg/day for 2 years. This was also considered an equivocal result. In conclusion, these studies demonstrated that acrylonitrile causes multiple carcinogenic effects after gavage administration to male and female B6

  9. Inhalation pharmacokinetics of ethylbenzene in B6C3F1 mice

    SciTech Connect

    Charest-Tardif, G.; Tardif, R.; Krishnan, K. . E-mail: Kannan.krishnan@umontreal.ca

    2006-01-15

    The objective of the present study was to characterize the inhalation pharmacokinetics of ethylbenzene (EB) in male and female B6C3F1 mice following single and repeated exposures. Initially, groups of 28 male and female mice were exposed for 4 h to 75, 200, 500, or 1000 ppm in order to determine potential non-linearity in the kinetics of EB. Then, groups of male and female mice were exposed for 6 h to 75 ppm and 750 ppm (corresponding to the NTP exposures) for 1 or 7 consecutive days, to evaluate whether EB kinetics was altered during repeated exposures, The maximal blood concentration (C {sub max}; mean {+-} SD, n = 4) observed in female mice at the end of a 4-h exposure to 75, 200, 500, and 1000 ppm was 0.53 {+-} 0.18, 2.26 {+-} 0.38, 19.17 {+-} 2.74, and 82.36 {+-} 16.66 mg/L, respectively. The areas under the concentration vs. time curve (AUCs) following 4-h exposure to 75, 200, 500, and 1000 ppm were 88.5, 414.0, 3612.2, and 19,104.1 mg/L/min, respectively, in female mice, and 116.7, 425.7, 3148.3, and 16,039.1 mg/L/min in male mice. The comparison of C {sub max} and the kinetic profile of EB in mice exposed to 75 ppm suggests that they are similar between 1-day and 7-day exposures. However, at 750 ppm, the rate of EB elimination would appear to be greater after repeated exposures than single exposure, the pattern being evident in both male and female mice. Overall, the single and repeated exposure pharmacokinetic data collected in the present study suggest that EB kinetics is saturable at exposure concentrations exceeding 500 ppm (and therefore at 750 ppm used in the NTP mouse cancer bioassay) but is in the linear range at the lower concentration used in the bioassay (75 ppm). These data suggest that consideration of the nature and magnitude of non-linear kinetics and induction of metabolism during repeated exposures is essential for the conduct of a scientifically sound analysis of EB cancer dose-response data collected in B6C3F1 mice.

  10. An investigation of several factors involved in a finite difference procedure for analyzing the transonic flow about harmonically oscillating airfoils and wings

    NASA Technical Reports Server (NTRS)

    Ehlers, F. E.; Sebastian, J. D.; Weatherill, W. H.

    1979-01-01

    Analytical and empirical studies of a finite difference method for the solution of the transonic flow about harmonically oscillating wings and airfoils are presented. The procedure is based on separating the velocity potential into steady and unsteady parts and linearizing the resulting unsteady equations for small disturbances. Since sinusoidal motion is assumed, the unsteady equation is independent of time. Three finite difference investigations are discussed including a new operator for mesh points with supersonic flow, the effects on relaxation solution convergence of adding a viscosity term to the original differential equation, and an alternate and relatively simple downstream boundary condition. A method is developed which uses a finite difference procedure over a limited inner region and an approximate analytical procedure for the remaining outer region. Two investigations concerned with three-dimensional flow are presented. The first is the development of an oblique coordinate system for swept and tapered wings. The second derives the additional terms required to make row relaxation solutions converge when mixed flow is present. A finite span flutter analysis procedure is described using the two-dimensional unsteady transonic program with a full three-dimensional steady velocity potential.

  11. A systems approach to high performance oscillators

    NASA Technical Reports Server (NTRS)

    Stein, S. R.; Manney, C. M., Jr.; Walls, F. L.; Gray, J. E.; Besson, R. J.

    1978-01-01

    The purpose of this paper is to show how systems composed of multiple oscillators and resonators can achieve superior performance compared to a single oscillator. Experimental results are presented for two systems based on quartz crystals which provide state-of-the-art stability over a much wider range of averaging times than has been previously achieved. One system has achieved a factor of five improvement in noise floor compared to all previously reported results.

  12. Frequencies of solar oscillations

    NASA Technical Reports Server (NTRS)

    Libbrecht, K. G.; Woodard, M. F.; Kaufman, J. M.

    1990-01-01

    Solar oscillations have been observed at three different spatial scales at Big Bear Solar Observatory during 1986-1987 and, using three data sets, a new and more accurate table of solar oscillation frequencies has been compiled. The oscillations, which are presented as functions of radial order n and spherical harmonic degree l, are averages over azimuthal order and therefore approximate the normal mode frequencies of a nonrotating, spherically symmetric sun, near solar minimum. The table contains frequencies for most of the solar p and f modes with l between 0 and 1860, n between 0 and 26, and oscillation mode frequencies between 1.0 and 5.3.

  13. Down-regulation of semaphorin 3F in rat retinal ganglion cells in response to optic nerve crush.

    PubMed

    Ko, Ji-Ae; Minamoto, Akira; Sugimoto, Yosuke; Kiuchi, Yoshiaki

    2016-07-01

    Glaucoma is characterized by degeneration of optic nerve axons and death of retinal ganglion cells (RGCs). Nerve crush and axotomy of the optic nerve are studied as models of RGC death in glaucoma and of axon regeneration. The mechanisms underlying the response of RGCs to axonal injury remain unclear, however. We have now examined the effects of optic nerve crush on the expression of members of the semaphorin family of neuronal guidance proteins in the rat retina. The expression of semaphorin 3F (Sema3F) in the retina was down-regulated at both the mRNA and protein levels at 7 days after optic nerve injury, whereas that of Sema3A, Sema3B or Sema3C remained unaffected. Immunohistofluorescence analysis and laser capture microdissection followed by reverse transcription-polymerase chain reaction analysis revealed that this loss of Sema3F expression occurred in the RGC layer of the retina. Furthermore, antibody-mediated neutralization of secreted Sema3F in retinal organ culture resulted in down-regulation of neuron-specific βIII-tubulin (Tuj-1 antigen), a marker of RGCs. Our results suggest that Sema3F may contribute to the regulation of RGC function or survival and therefore warrants further investigation as a potential mediator of neuroprotection. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27309587

  14. Sum Rules of Charm C P Asymmetries beyond the SU(3 ) F Limit

    NASA Astrophysics Data System (ADS)

    Müller, Sarah; Nierste, Ulrich; Schacht, Stefan

    2015-12-01

    We find new sum rules between direct C P asymmetries in D meson decays with coefficients that can be determined from a global fit to branching ratio data. Our sum rules eliminate the penguin topologies P and P A , which cannot be determined from branching ratios. In this way, we can make predictions about direct C P asymmetries in the standard model without ad hoc assumptions on the sizes of penguin diagrams. We consistently include first-order SU(3 ) F breaking in the topological amplitudes extracted from the branching ratios. By confronting our sum rules with future precise data from LHCb and Belle II, one will identify or constrain new-physics contributions to P or P A . The first sum rule correlates the C P asymmetries aCP dir in D0→K+K-, D0→π+π- , and D0→π0π0. We study the region of the aCP dir(D0→π+π-)-aCP dir(D0→π0π0) plane allowed by current data and find that our sum rule excludes more than half of the allowed region at 95% C.L. Our second sum rule correlates the direct C P asymmetries in D+→K¯0K+, Ds+→K0π+, and Ds+→K+π0.

  15. Sum Rules of Charm CP Asymmetries beyond the SU(3)_{F} Limit.

    PubMed

    Müller, Sarah; Nierste, Ulrich; Schacht, Stefan

    2015-12-18

    We find new sum rules between direct CP asymmetries in D meson decays with coefficients that can be determined from a global fit to branching ratio data. Our sum rules eliminate the penguin topologies P and PA, which cannot be determined from branching ratios. In this way, we can make predictions about direct CP asymmetries in the standard model without ad hoc assumptions on the sizes of penguin diagrams. We consistently include first-order SU(3)_{F} breaking in the topological amplitudes extracted from the branching ratios. By confronting our sum rules with future precise data from LHCb and Belle II, one will identify or constrain new-physics contributions to P or PA. The first sum rule correlates the CP asymmetries a_{CP}^{dir} in D^{0}→K^{+}K^{-}, D^{0}→π^{+}π^{-}, and D^{0}→π^{0}π^{0}. We study the region of the a_{CP}^{dir}(D^{0}→π^{+}π^{-})-a_{CP}^{dir}(D^{0}→π^{0}π^{0}) plane allowed by current data and find that our sum rule excludes more than half of the allowed region at 95% C.L. Our second sum rule correlates the direct CP asymmetries in D^{+}→K[over ¯]^{0}K^{+}, D_{s}^{+}→K^{0}π^{+}, and D_{s}^{+}→K^{+}π^{0}. PMID:26722915

  16. Noncollinear magnetization between surface and bulk Y3F e5O12

    NASA Astrophysics Data System (ADS)

    Wu, Po-Hsun; Huang, Ssu-Yen

    2016-07-01

    Yttrium iron garnet (YIG, Y3F e5O12 ) is a magnetic insulator that has been widely used to generate spin-wave spin current via the longitudinal spin Seebeck effect. Spin current can be converted to charge current by the inverse spin Hall effect (ISHE) in an attached metal layer with a spin direction given by the magnetization of the YIG. However, both the ISHE voltage from the thermal transport measurement and the magnetoresistance (MR) from the electrical transport measurement of the metal/YIG structure show a clear plateau behavior in the low-field range, which is inconsistent with the magnetization reversal behavior of the YIG slab. In this work, we provide direct evidences by using the highly sensitive micro-magneto-optic Kerr effect (micro-MOKE) measurement to demonstrate that the plateau behavior in the thermal and electrical transport measurement of metal/YIG is due to the noncollinear magnetization configuration between the bulk and surface of YIG. In addition, keeping the measured surface of YIG unaltered, we show that its surface magnetization can be systematically controlled by varying the thickness. We further demonstrate that the magnetic coupling between the surface magnetization of YIG and an attached ferromagnetic layer exhibits long-range interaction due to the magnetic dipole-dipole interaction.

  17. Alignment of CH3F in para-H2 crystal studied by IR quantum cascade laser polarization spectroscopy.

    PubMed

    Kawasaki, Hiroyuki; Mizoguchi, Asao; Kanamori, Hideto

    2016-05-14

    In order to investigate the alignment of CH3F in para-H2 crystals, high resolution polarization spectroscopy of the ν3 vibrational band is studied using a quantum cascade laser at 1040 cm(-1). It is found that the main and satellite series of peaks in the ν3 vibrational band of CH3F have the same polarization dependence. This result supports the previously proposed cluster model with ortho-H2 in first and second nearest neighbor sites. The observed polarization dependence function is well described by a simple six-axis void model in which CH3F is not aligned along the c-axis of the crystal but tilted to 64.9(3)° from it. PMID:27179483

  18. Alignment of CH3F in para-H2 crystal studied by IR quantum cascade laser polarization spectroscopy

    NASA Astrophysics Data System (ADS)

    Kawasaki, Hiroyuki; Mizoguchi, Asao; Kanamori, Hideto

    2016-05-01

    In order to investigate the alignment of CH3F in para-H2 crystals, high resolution polarization spectroscopy of the ν3 vibrational band is studied using a quantum cascade laser at 1040 cm-1. It is found that the main and satellite series of peaks in the ν3 vibrational band of CH3F have the same polarization dependence. This result supports the previously proposed cluster model with ortho-H2 in first and second nearest neighbor sites. The observed polarization dependence function is well described by a simple six-axis void model in which CH3F is not aligned along the c-axis of the crystal but tilted to 64.9(3)° from it.

  19. The H2O-CH3F Complex: a Combined Microwave and Infrared Spectroscopic Study Supported by Structure Calculations

    NASA Astrophysics Data System (ADS)

    Gnanasekar, Sharon Priya; Goubet, Manuel; Arunan, Elangannan; Georges, Robert; Soulard, Pascale; Asselin, Pierre; Huet, T. R.; Pirali, Olivier

    2015-06-01

    The H2O-CH3F complex could have two geometries, one with a hydrogen bond and one with the newly proposed carbon bond. While in general carbon bonds are weaker than hydrogen bonds, this complex appears to have comparable energies for the two structures. Infrared (IR) and microwave (MW) spectroscopic measurements using, respectively, the Jet-AILES apparatus and the FTMW spectrometer at the PhLAM laboratory, have been carried out to determine the structure of this complex. The IR spectrum shows the formation of the CH3F- H2O hydrogen bonded complex and small red-shifts in OH frequency most probably due to (CH3F)m-(H2O)n clusters. Noticeably, addition of CH_3F in the mixture promotes the formation of small water clusters. Preliminary MW spectroscopic measurements indicate the formation of the hydrogen bonded complex. So far, we have no experimental evidence for the carbon bonded structure. However, calculations of the Ar-CH3F complex show three energetically equivalent structures: a T-shape, a "fluorine" bond and a carbon bond. The MW spectrum of the (Ar)n-CH3F complexes is currently under analysis. Mani, D; Arunan, E. Phys. Chem. Chem. Phys. 2013, 15, 14377. Cirtog, M; Asselin, P; Soulard, P; Tremblay, B; Madebene, B; Alikhani, M. E; Georges, R; Moudens, A; Goubet, M; Huet, T.R; Pirali, O; Roy, P. J. Phys. Chem. A. 2011, 115, 2523 Kassi, S; Petitprez, D; Wlodarczak, G. J. Mol. Struct. 2000, 517-518, 375

  20. Active-bridge oscillator

    DOEpatents

    Wessendorf, Kurt O.

    2001-01-01

    An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.

  1. Investigating Magnetic Oscillations.

    ERIC Educational Resources Information Center

    Brueningsen, Christopher A.

    1993-01-01

    Studies magnetic oscillation using an air track. Ceramic magnets are attached to the cart and also are used as dampeners in place of the springs. The resulting oscillations are fairly sinusoidal and is a good example of simple harmonic motion. (MVL)

  2. HIGH POWER PULSED OSCILLATOR

    DOEpatents

    Singer, S.; Neher, L.K.

    1957-09-24

    A high powered, radio frequency pulse oscillator is described for generating trains of oscillations at the instant an input direct voltage is impressed, or immediately upon application of a light pulse. In one embodiment, the pulse oscillator comprises a photo-multiplier tube with the cathode connected to the first dynode by means of a resistor, and adjacent dynodes are connected to each other through adjustable resistors. The ohmage of the resistors progressively increases from a very low value for resistors adjacent the cathode to a high value adjacent the plate, the last dynode. Oscillation occurs with this circuit when a high negative voltage pulse is applied to the cathode and the photo cathode is bombarded. Another embodiment adds capacitors at the resistor connection points of the above circuit to increase the duration of the oscillator train.

  3. Immunotoxicity of nitrobenzene in female B6C3F1 mice.

    PubMed

    Burns, L A; Bradley, S G; White, K L; McCay, J A; Fuchs, B A; Stern, M; Brown, R D; Musgrove, D L; Holsapple, M P; Luster, M I

    1994-01-01

    Nitrobenzene (NBZ) is primarily employed as an oxidizing agent in the synthesis of analine and benzene compounds. It produces myelotoxic effects and effects on erythrocytes in both animal models and man. Reported hepatosplenomegaly and effects on the bone marrow are indicators that NBZ may be immunotoxic. In these studies, female B6C3F1 mice were exposed to 30, 100 and 300 mg/kg of NBZ in corn oil by gavage for 14 consecutive days. To assess the immunotoxic potential of NBZ, body and organ weights were determined and selected immunologic and host resistance responses were studied. In these studies, the liver and spleen appeared to be the primary target organs. Both liver and spleen weights were dose dependently increased. Gross histopathologic examinations revealed significant changes in the spleen, consisting of severe congestion of the red pulp areas with erythrocytes and reticulocytes. Serum chemistry profiles showed increases in alanine aminotransferase and aspartate aminotransferase activities, indicating liver toxicity. Hematologic studies showed a decrease in erythrocyte number and a concomitant increase in mean corpuscular hemoglobin and mean corpuscular volume. A dose-dependent increase in peripheral reticulocytes was also seen. DNA synthesis was enhanced, as was the number of formed elements and the number of monocyte/granulocyte stem cells in the bone marrow of treated mice. IgM responses were decreased and the phagocytic activity of macrophages in the liver was dose dependently increased with a concomitant decrease in the activities in the spleen and lung. Other immunological parameters examined were unchanged. Host resistance to microbial or viral infection was not markedly altered by NBZ; however, there were trends towards increased susceptibility where T-cell function contributes to host defense. These data indicate that NBZ-induced hemolysis and liver injury are linked to the observed alterations in bone marrow activity. PMID:7988385

  4. Chronic bioassays of chlorinated humic acids in B6C3F1 mice

    SciTech Connect

    van Duuren, B.L.; Melchionne, S.; Seidman, I.; Pereira, M.A.

    1986-11-01

    Humic acids (Fluka), chlorinated to carbon:chlorine (C:Cl) ratios of 1:1 and 1:0.3, were administered to B6C3F1 mice, 50 males and 50 females per group, in the drinking water at a total organic carbon (TOC) level of 0.5 g/L. The mice were 6 to 8 weeks old at the beginning of the bioassays. The doses used were based on short-term (8 weeks) evaluations for toxicity, palatability, and weight gain. The chronic bioassays included the following control groups: unchlorinated humic acids (0.5 g/L), no-treatment (100 males and 100 females), dibromoethane (DBE, 2.0 mM in drinking water; positive control) and 0.44% sodium chloride in drinking water, i.e., at the same concentration as those receiving chlorinated humic acids. The chlorinated humic acids were prepared freshly and chemically assayed once per week. All chemicals were, with the exception of DBE, administered for 24 months; DBE was administered for 18 months. The volumes of solutions consumed were measured once weekly. All treatment groups showed normal weight gain except the DBE group. No markedly significant increases in tumor incidences were evident in any of the organs and tissues examined in the chlorinated humic acid groups compared to unchlorinated humic acids and the no-treatment control groups. DBE caused the expected high incidence of squamous carcinomas of the forestomach. The chlorinated humic acids tested contained direct-acting alkylating agents, based on their reactivity with p-nitrobenzylpyridine (PNBP), and showed mutagenic activity in S. typhimurium.

  5. Toxicokinetics of acrylamide and glycidamide in B6C3F{sub 1} mice

    SciTech Connect

    Doerge, Daniel R. . E-mail: ddoerge@nctr.fda.gov; Young, John F.; McDaniel, L. Patrice; Twaddle, Nathan C.; Churchwell, Mona I.

    2005-02-01

    Acrylamide (AA) is a widely studied industrial chemical that is neurotoxic, mutagenic to somatic and germ cells, and carcinogenic in rodents. The recent discovery of AA at ppm levels in a wide variety of commonly consumed foods has energized research efforts worldwide to define toxic mechanisms, particularly toxicokinetics and bioavailability. This study compares the toxicokinetics of AA and its epoxide metabolite glycidamide (GA) in serum and tissues of male and female B6C3F1 mice following acute dosing by intravenous, gavage, and dietary routes at 0.1 mg/kg AA or intravenous and gavage dosing with an equimolar amount of GA. AA was rapidly absorbed from oral dosing, was widely distributed to tissues, was efficiently converted to GA, and increased levels of GA-DNA adducts were observed in liver after complete elimination from serum. GA dosing also resulted in rapid absorption, wide distribution to tissues, and produced liver DNA adduct levels that were approximately 40% higher than those from an equimolar dose of AA. While oral administration was found to attenuate AA bioavailability to 23% from the diet and to 32-52% from aqueous gavage, a first-pass effect or other kinetic change resulted in higher relative internal exposure to GA when compared to the intravenous route. A similar effect on relative GA exposure was also evident as the administered dose was reduced, which suggests that as dosing rate decreases, the conversion of AA to GA is more efficient. These findings are critical to the assessment of genotoxicity of AA at low doses in the food supply, which appears to depend on total exposure to GA.

  6. Combustion oscillation control by cyclic fuel injection

    SciTech Connect

    Richards, G.A.; Yip, M.J.; Robey, E.; Cowell, L.; Rawlins, D.

    1997-04-01

    A number of recent articles have demonstrated the use of active control to mitigate the effects of combustion instability in afterburner and dump combustor applications. In these applications, cyclic injection of small quantities of control fuel has been proposed to counteract the periodic heat release that contributes to undesired pressure oscillations. This same technique may also be useful to mitigate oscillations in gas turbine combustors, especially in test rig combustors characterized by acoustic modes that do not exist in the final engine configuration. To address this issue, the present paper reports on active control of a subscale, atmospheric pressure nozzle.combustor arrangement. The fuel is natural gas. Cyclic injection of 14 percent control fuel in a premix fuel nozzle is shown to reduce oscillating pressure amplitude by a factor of 0.30 (i.e., {minus}10 dB) at 300 Hz. Measurement of the oscillating heat release is also reported.

  7. Combustion oscillation control by cyclic fuel injection

    SciTech Connect

    Richards, G.A.; Yip, M.J.; Robey, E.; Cowell, L.; Rawlins, D.

    1995-04-01

    A number of recent articles have demonstrated the use of active control to mitigate the effects of combustion instability in afterburner and dump combustor applications. In these applications, cyclic injection of small quantities of control fuel has been proposed to counteract the periodic heat release that contributes to undesired pressure oscillations. This same technique may also be useful to mitigate oscillations in gas turbine combustors, especially in test rig combustors characterized by acoustic modes that do not exist in the final engine configuration. To address this issue, the present paper reports on active control of a subscale, atmospheric pressure nozzle/combustor arrangement. The fuel is natural gas. Cyclic injection of 14% control fuel in a premix fuel nozzle is shown to reduce oscillating pressure amplitude by a factor of 0.30 (i.e., {approximately}10 dB) at 300 Hz. Measurement of the oscillating heat release is also reported.

  8. Global Gene Profiling of Spontaneous Hepatocellular Carcinoma in B6C3F1 Mice: Similarities in the Molecular Landscape with Human Liver Cancer

    PubMed Central

    Hoenerhoff, Mark J.; Pandiri, Arun R.; Lahousse, Stephanie A.; Hong, Hu-Hua; Ton, Tai-Vu; Masinde, Tiwanda; Auerbach, Scott S.; Gerrish, Kevin; Bushel, Pierre R.; Shockley, Keith R.; Peddada, Shyamal D.; Sills, Robert C.

    2016-01-01

    Hepatocellular carcinoma (HCC) is an important cause of morbidity and mortality worldwide. Although the risk factors of human HCC are well known, the molecular pathogenesis of this disease is complex, and in general, treatment options remain poor. The use of rodent models to study human cancer has been extensively pursued, both through genetically engineered rodents and rodent models used in carcinogenicity and toxicology studies. In particular, the B6C3F1 mouse used in the National Toxicology Program (NTP) two-year bioassay has been used to evaluate the carcinogenic effects of environmental and occupational chemicals, and other compounds. The high incidence of spontaneous HCC in the B6C3F1 mouse has challenged its use as a model for chemically induced HCC in terms of relevance to the human disease. Using global gene expression profiling, we identify the dysregulation of several mediators similarly altered in human HCC, including re-expression of fetal oncogenes, upregulation of protooncogenes, downregulation of tumor suppressor genes, and abnormal expression of cell cycle mediators, growth factors, apoptosis regulators, and angiogenesis and extracellular matrix remodeling factors. Although major differences in etiology and pathogenesis remain between human and mouse HCC, there are important similarities in global gene expression and molecular pathways dysregulated in mouse and human HCC. These data provide further support for the use of this model in hazard identification of compounds with potential human carcinogenicity risk, and may help in better understanding the mechanisms of tumorigenesis resulting from chemical exposure in the NTP two-year carcinogenicity bioassay. PMID:21571946

  9. Search and Rescue Aircrewman/HH3F Avionics, 2-11. Military Curriculum Materials for Vocational and Technical Education.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This self-paced, individualized course, adapted from military curriculum materials for use in vocational and technical education, teaches students the skills needed to become a qualified avionics worker and aircrew rescuer on the HH-3F helicopter. The course materials consist of four pamphlets: two student workbooks and two student syllabuses. The…

  10. Lattice site dependent cathodoluminescence behavior and surface chemical changes in a Sr5(PO4)3F host

    NASA Astrophysics Data System (ADS)

    Nagpure, I. M.; Pitale, Shreyas S.; Coetsee, E.; Ntwaeaborwa, O. M.; Terblans, J. J.; Swart, H. C.

    2012-05-01

    Eu activated Sr5(PO4)3F phosphor powders have been subjected to the electron bombardment at 2 keV (10 μA) at an oxygen pressure of 1×10-6 Torr. The synthesized Sr5(PO4)3F phosphor was identical to the hexagonal apatite structure, with the Sr present at two different sites Cs (S1) and C3 (S2) in the Sr5(PO4)3F host, as inferred from the crystallographic study. Cathodoluminescence (CL) and Auger electron spectroscopy of the phosphor excited by the same electron beam were used to monitor changes in the surface state during prolonged electron bombardment. A direct correlation between the surface reactions and the degradation of the CL brightness was observed. Both C and F were depleted from the surface during electron bombardment. The postulated mechanism for the electron stimulated chemical reactions on the phosphor surface is electron beam dissociation of molecular species to atomic species, which subsequently react with C to form volatile compounds CO2, CH4, etc. and with Sr5(PO4)3F to form a non luminescence layer of metal oxides of Sr and P.

  11. MULTIPLE-SITE CARCINOGENICITY OF BENZENE IN FISCHER 344 RATS AND B6C3F MICE

    EPA Science Inventory

    Two-year toxicology and carcinogenesis studies of benzene were conducted in groups of 50 F344/N rats and 50 B6C3F1 mice of each sex and for each of three exposure doses and vehicle controls. hese studies were conducted because of large production volume and widespread human expos...

  12. Evaluation of Radial Flow Fluidized Filter (R3F) Followed by Microfiltration and Ultrafiltration Systems in Calimesa, California

    EPA Science Inventory

    U.S. EPA coordinated a field study with South Mesa Water Utility to look for treatment alternatives for California State Project Water in the small community of Calimesa, California. EPA evaluated the performance of a system comprised of Radial Flow Fluidized Filtration (R3f) fo...

  13. Immunotoxicological Profile of Chloroform in Female B6c3f1 Mice When Administered In Drinking Water

    EPA Science Inventory

    Chloroform can be formed as a disinfection by-product during water chlorination, one of the primary modalities for purifying municipal water supplies for human consumption. The goal of this study was to characterize the immunotoxic effects of chloroform in female B6C3F1 mice when...

  14. 29 CFR 780.105 - “Primary” and “secondary” agriculture under section 3(f).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false âPrimaryâ and âsecondaryâ agriculture under section 3(f... EXEMPTIONS APPLICABLE TO AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT General Scope of Agriculture Introductory § 780.105 “Primary” and...

  15. 29 CFR 780.105 - “Primary” and “secondary” agriculture under section 3(f).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false âPrimaryâ and âsecondaryâ agriculture under section 3(f... EXEMPTIONS APPLICABLE TO AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT General Scope of Agriculture Introductory § 780.105 “Primary” and...

  16. 29 CFR 780.105 - “Primary” and “secondary” agriculture under section 3(f).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false âPrimaryâ and âsecondaryâ agriculture under section 3(f... EXEMPTIONS APPLICABLE TO AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT General Scope of Agriculture Introductory § 780.105 “Primary” and...

  17. 29 CFR 780.105 - “Primary” and “secondary” agriculture under section 3(f).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false âPrimaryâ and âsecondaryâ agriculture under section 3(f... EXEMPTIONS APPLICABLE TO AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT General Scope of Agriculture Introductory § 780.105 “Primary” and...

  18. 29 CFR 780.105 - “Primary” and “secondary” agriculture under section 3(f).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false âPrimaryâ and âsecondaryâ agriculture under section 3(f... EXEMPTIONS APPLICABLE TO AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT General Scope of Agriculture Introductory § 780.105 “Primary” and...

  19. HEPATOCARCINOGENICITY OF CHLORAL HYDRATE, 2-CHLOROACETALDEHYDE, AND DICHLOROACETIC ACID IN THE MALE B6C3F1 MOUSE

    EPA Science Inventory

    Chloral hydrate (CH) and 2-chloroacetaldehyde (CAA) have been identified as chlorination by-products in drinking water. oth chemicals are genotoxic, but their carcinogenic potential had not been adequately tested. hese bioassays were conducted using male B6C3F1 mice exposed to 1 ...

  20. Altered global histone-trimethylation code and H3F3A-ATRX mutation in pediatric GBM.

    PubMed

    Pathak, Pankaj; Jha, Prerana; Purkait, Suvendu; Sharma, Vikas; Suri, Vaishali; Sharma, Mehar C; Faruq, Mohammed; Suri, Ashish; Sarkar, Chitra

    2015-02-01

    Mutations in H3.3-ATRX-DAXX chromatin remodeling pathway have been reported in pediatric GBMs. H3.3 (H3F3A) mutations may affect transcriptional regulation by altered global histone-methylation. Therefore, we analyzed yet partly understood global histone code (H3K-4/9/27/36) trimethylation pattern in H3F3A-ATRX mutants and wild-type. H3F3A, HIST1H3B, IDH1, ATRX, DAXX and Tp53 mutations were identified by sequencing/immunohistochemistry in 27 pediatric GBMs. Global histone-methylation H3K-4/9/27/36me3 and Polycomb-protein EZH2 expression were evaluated by immunohistochemistry. H3F3A-ATRX mutation was observed in 66.7 % (18/27) of pediatric GBMs. K27M and G34R-H3F3A mutations were found in 37 % (10/27) and 14.8 % (4/27) patients respectively. G34V-H3F3A, HIST1H3B and IDH1 mutations were absent. Notably, commonest global histone-methylation mark lost was H3K27me3 (17/25, 68 %) followed by H3K4me3 (45.5 %, 10/22) and H3K9me3 (18.2 %, 4/22). Global H3K36me3 showed no loss. Most significant observation was loss of one or more histone-trimethylation mark in 80 % (20/25) pediatric GBMs. Notably, simultaneous loss of H3K27me3 and H3K4me3 were present in 7/22 (31.8 %) of pediatric GBMs. Low expression of EZH2 was found in 12/24 (50 %) of cases. However no significant correlation of loss of histone-marks or EZH2 expression with H3F3A-ATRX mutants (loss of at least one histone-marks in 87.5 % (14/16) cases) versus wild-types (loss of at least one histone-marks in 75 % (6/8) cases) was seen. The present study highlights for the first time combinatorial loss of one or more histone-trimethylation marks associated with majority of pediatric GBMs and the finding suggests significant role of histone-code in the molecular biology that underlies pediatric GBMs. Hence therapies for patients with particular combinations of histone modifications present opportunity to design innovative patient-tailored treatment protocols. PMID:25479829

  1. Optical emission spectroscopic studies and comparisons of CH{sub 3}F/CO{sub 2} and CH{sub 3}F/O{sub 2} inductively coupled plasmas

    SciTech Connect

    Lou, Qiaowei; Kaler, Sanbir; Donnelly, Vincent M. Economou, Demetre J.

    2015-03-15

    A CH{sub 3}F/CO{sub 2} inductively coupled plasma (ICP), sustained in a compact plasma reactor, was investigated as a function of power (5–400 W) and feed gas composition, at a pressure of 10 mTorr, using optical emission spectroscopy and rare gas actinometry. Number densities of H, F, and O increased rapidly between 74% and 80% CO{sub 2}, ascribed to the transition from polymer-covered to polymer-free reactor walls, similar to that found previously in CH{sub 3}F/O{sub 2} ICPs at 48% O{sub 2}. Below 40% O{sub 2} or CO{sub 2}, relative emission intensity ratios were almost identical for most key species in CH{sub 3}F/O{sub 2} and CH{sub 3}F/CO{sub 2} ICPs except for higher OH/Xe (a qualitative measure of OH and H{sub 2}O densities) over the full range of CH{sub 3}F/O{sub 2} composition. The number density of H, F, and O increased with power in CH{sub 3}F/CO{sub 2} (20%/80%) plasmas (polymer-free walls), reaching 4.0, 0.34, and 1.6 × 10{sup 13}/cm{sup 3}, respectively, at 300 W. The CO number density increased with power and was estimated, based on self-actinometry, to be 8.8 × 10{sup 13}/cm{sup 3} at 300 W. The CO{sub 2} number density was independent of power below 40 W (where very little decomposition occurred), and then decreased rapidly with increasing power, reaching 2.8 × 10{sup 13}/cm{sup 3} at 300 W, corresponding to 83% dissociation. Films deposited on p-Si, 10 cm from the open, downstream end of the plasma reactor, were analyzed by x-ray photoelectron spectroscopy. Between 10% and 40% CO{sub 2} or O{sub 2} addition to CH{sub 3}F, film deposition rates fell and O content in the films increased. Faster deposition rates in CH{sub 3}F/CO{sub 2} plasmas were ascribed mainly to a larger thermodynamic driving force to form solid carbon, compared with CH{sub 3}F/O{sub 2} plasmas. Oxygen content in the films increased with increasing CO{sub 2} or O{sub 2} addition, but for the same deposition rate, no substantial differences were

  2. High Resolution Infrared Spectroscopy of CH_3F-({ortho}-H_2){n} Cluster in Solid {para}-H_2

    NASA Astrophysics Data System (ADS)

    Kawasaki, Hiroyuki; Mizoguchi, Asao; Kanamori, Hideto

    2015-06-01

    The absorption spectrum of the ν3 (C-F stretching) mode of CH_3F in solid {para}-H_2 by FTIR showed a series of equal interval peaks. Their interpretation was that the {}-th peak of this series was due to CH_3F-({ortho}-H_2){n} clusters which were formed CH_3F and {n}'s {ortho}-H_2 in first nearest neighbor sites of the {para}-H_2 crystal with {hcp} structure. In order to understand this system in more detail, we have studied these peaks, especially {n} = 0 - 3 corresponding to 1037 - 1041 wn, by using high-resolution and high-sensitive infrared quantum cascade (QC) laser spectroscopy. Before now, we found many peaks around each {n}-th peak of the cluster, which we didn't know their origins. We observed photochromic phenomenon of these peaks by taking an advantage of the high brightness of the laser. In this study, we focus on satellite series consisting of six peaks which locate at the lower energy side of each main peak. All the peaks showed a common red shouldered line profile, which corresponds to partly resolved transitions of {ortho}- and {para}- CH_3F. The spectral pattern and time behavior of the peaks may suggest that these satellite series originate from a family of CH_3F clusters involving {ortho}-H_2 in second nearest neighbor sites. A model function assuming this idea is used to resolve the observed spectrum into each Lorentzian component, and then some common features of the satellite peaks are extracted and the physical meanings of them will be discussed. K. Yoshioka and D. T. Anderson, J. Chem. Phys. 119 (2003) 4731-4742 A. R. W. McKellar, A. Mizoguchi, and H. Kanamori, J. Chem. Phys. 135 (2011) 124511 A. R. W. McKellar, A. Mizoguchi, and H. Kanamori, Phys. Chem. Chem. Phys. 13 (2011) 11587-11589.

  3. Vacuum polarization and electron-positron plasma oscillations

    SciTech Connect

    Ruffini, R.; Vereshchagin, G. V.; Xue, S.-S.

    2008-01-03

    We study plasma oscillations of electrons-positron pairs created by the vacuum polarization in an uniform electric field. Our treatment, encompassing also the case of E>E{sub c}, shows the existence in both cases of a maximum Lorentz factor acquired by electrons and positrons and allows determination of the a maximal length of oscillation. We quantitatively estimate how plasma oscillations reduce the rate of pair creation and increase the time scale of the pair production.

  4. Suppression and revival of oscillation in indirectly coupled limit cycle oscillators

    NASA Astrophysics Data System (ADS)

    Sharma, P. R.; Kamal, N. K.; Verma, U. K.; Suresh, K.; Thamilmaran, K.; Shrimali, M. D.

    2016-09-01

    We study the phenomena of suppression and revival of oscillations in a system of limit cycle oscillators coupled indirectly via a dynamic local environment. The dynamics of the environment is assumed to decay exponentially with time. We show that for appropriate coupling strength, the decay parameter of the environment plays a crucial role in the emergent dynamics such as amplitude death (AD) and oscillation death (OD). We also show that introducing a feedback factor in the diffusion term revives the oscillations in this system. The critical curves for the regions of different emergent states as a function of coupling strength, decay parameter of the environment and feedback factor in the coupling are obtained analytically using linear stability analysis. These results are found to be consistent with the numerics and are also observed experimentally.

  5. Theoretical temperature-dependent branching ratios and laser thresholds of the 3F4 to 3H6 levels of Tm(3+) in ten garnets

    NASA Technical Reports Server (NTRS)

    Filer, Elizabeth D.; Barnes, Norman P.; Morrison, Clyde A.

    1991-01-01

    The calculated energy levels, the branching ratios, and the estimated thresholds for thulium operating on the 3F4 to 3H6 transitions are reported. Garnet materials with the general formula A3B2C3O12 are evaluated. Calculations are performed for the A side under the assumption of D2 symmetry. X-ray data available in the literature are used to evaluate the crystal-field components, A sub nm. Even-n components are employed to calculate the crystal-field splittings within the manifold. Thermal occupation factors are determined in a straightforward manner using a Boltzmann distribution for the respective manifolds. Odd-n components are applied to calculate the transition probabilities for electric field transitions. It is determined that the magnetic dipole contributions to the transition probability are comparable to the electric dipole contributions in some cases. Thresholds as a function of the density of thulium atoms are calculated.

  6. Oscillating fluid power generator

    DOEpatents

    Morris, David C

    2014-02-25

    A system and method for harvesting the kinetic energy of a fluid flow for power generation with a vertically oriented, aerodynamic wing structure comprising one or more airfoil elements pivotably attached to a mast. When activated by the moving fluid stream, the wing structure oscillates back and forth, generating lift first in one direction then in the opposite direction. This oscillating movement is converted to unidirectional rotational movement in order to provide motive power to an electricity generator. Unlike other oscillating devices, this device is designed to harvest the maximum aerodynamic lift forces available for a given oscillation cycle. Because the system is not subjected to the same intense forces and stresses as turbine systems, it can be constructed less expensively, reducing the cost of electricity generation. The system can be grouped in more compact clusters, be less evident in the landscape, and present reduced risk to avian species.

  7. A novel photonic oscillator

    NASA Technical Reports Server (NTRS)

    Yao, X. S.; Maleki, L.

    1995-01-01

    We report a novel oscillator for photonic RF systems. This oscillator is capable of generating high-frequency signals up to 70 GHz in both electrical and optical domains and is a special voltage-controlled oscillator with an optical output port. It can be used to make a phase-locked loop (PLL) and perform all functions that a PLL is capable of for photonic systems. It can be synchronized to a reference source by means of optical injection locking, electrical injection locking, and PLL. It can also be self-phase locked and self-injection locked to generate a high-stability photonic RF reference. Its applications include high-frequency reference regeneration and distribution, high-gain frequency multiplication, comb-frequecy and square-wave generation, carrier recovery, and clock recovery. We anticipate that such photonic voltage-controlled oscillators (VCOs) will be as important to photonic RF systems as electrical VCOs are to electrical RF systems.

  8. High frequency nanotube oscillator

    DOEpatents

    Peng, Haibing; Zettl, Alexander K.

    2012-02-21

    A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.

  9. Quasioptical Josephson Oscillator

    NASA Astrophysics Data System (ADS)

    Wengler, Michael J.

    1994-09-01

    The Quasioptical Josephson Oscillator (QJO) is a 2-D array of between 100 and 1,000,000 Josephson junctions, each at the center of a small dipole antenna. HYPRES, Inc. of Elmsford, NY has fabricated test chips which have demonstrated 0.35 microwatts radiation at 190 CHz in one case, and 0.7 microwatts radiation at 345 GHz in another case. A significant understanding of the 2-D oscillators was developed through theoretical and numerical calculations.

  10. Ultrastable Multigigahertz Photonic Oscillator

    NASA Technical Reports Server (NTRS)

    Logan, Ronald T., Jr.

    1996-01-01

    Novel photonic oscillator developed to serve as ultrastable source of microwave and millimeter-wave signals. In system, oscillations generated photonically, then converted to electronic form. Includes self-mode-locked semiconductor laser producing stream of pulses, detected and fed back to laser as input. System also includes fiber-optic-delay-line discriminator, which detects fluctuations of self-mode-locking frequency and generates error signal used in negative-feedback loop to stabilize pulse-repetition frequency.

  11. Current oscillations in nanopores

    NASA Astrophysics Data System (ADS)

    Hyland, Brittany

    We develop a simple phenomenological model to describe current oscillations in single, conically shaped nanopores. The model utilizes aspects of reaction rate theory, electrochemical oscillators, and nonlinear dynamical systems. Time series of experimental data were analyzed and compared to time series simulated using the model equations. There is good qualitative agreement between experiment and simulation, though the model needs to be improved in order to obtain better quantitative agreement.

  12. High Frequency Low Amplitude Temperature Oscillations in Loop Heat Pipe Operation

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2003-01-01

    Contents include the following: 1. High frequency, low amplitude temperature oscillations: LHP operation - governing equations; interactions among LHP components; factors affecting low amplitude temperature oscillations. 2. Test results. 3. Conclusions.

  13. The mechanism of the area negative thermal expansion in KBe2BO3F2 family crystals: A first-principles study

    NASA Astrophysics Data System (ADS)

    Jiang, Xingxing; Molokeev, Maxim S.; Li, Wei; Wu, Shaofan; Lin, Zheshuai; Wu, Yicheng; Chen, Chuangtian

    2016-02-01

    A very recent study demonstrated that the KBe2BO3F2 (KBBF) family of crystals, including KBBF, RbBe2BO3F2, and CsBe2BO3F2, are the only known borates exhibiting a rarely occurring isotropic area negative thermal expansion (NTE) behavior, over a very large temperature range. In the present work, the NTE mechanism in these crystals is comprehensively investigated using the first-principles calculations. It is revealed that the area NTE behavior mainly originates from the concerted distortion of [BeO3F] tetrahedra in the two-dimensional [Be2BO3F2]∞ framework with respect to temperature, while the [BO3] triangles remain almost rigid. Moreover, the different magnitude of NTE effect in the three crystals is attributed to the interaction difference between the alkali metal atoms (K, Rb, or Cs) and the [Be2BO3F2]∞ layer.

  14. Oscillating asymmetric dark matter

    SciTech Connect

    Tulin, Sean; Yu, Hai-Bo; Zurek, Kathryn M. E-mail: haiboyu@umich.edu

    2012-05-01

    We study the dynamics of dark matter (DM) particle-antiparticle oscillations within the context of asymmetric DM. Oscillations arise due to small DM number-violating Majorana-type mass terms, and can lead to recoupling of annihilation after freeze-out and washout of the DM density. Asymmetric DM oscillations 'interpolate' between symmetric and asymmetric DM freeze-out scenarios, and allow for a larger DM model-building parameter space. We derive the density matrix equations for DM oscillations and freeze-out from first principles using nonequilibrium field theory, and our results are qualitatively different than in previous studies. DM dynamics exhibits particle-vs-antiparticle 'flavor' effects, depending on the interaction type, analogous to neutrino oscillations in a medium. 'Flavor-sensitive' DM interactions include scattering or annihilation through a new vector boson, while 'flavor-blind' interactions include scattering or s-channel annihilation through a new scalar boson. In particular, we find that flavor-sensitive annihilation does not recouple when coherent oscillations begin, and that flavor-blind scattering does not lead to decoherence.

  15. Periodically oscillating plasma sphere

    SciTech Connect

    Park, J.; Nebel, R.A.; Stange, S.; Murali, S. Krupakar

    2005-05-15

    The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very high densities and temperatures during the collapse phase of the oscillation. A requirement for POPS is that the electron injection produces a stable harmonic oscillator potential. This has been demonstrated in a gridded inertial electrostatic confinement device and verified by particle simulation. Also, the POPS oscillation has been confirmed experimentally through observation that the ions in the potential well exhibit resonance behavior when driven at the POPS frequency. Excellent agreement between the observed POPS frequencies and the theoretical predictions has been observed for a wide range of potential well depths and three different ion species. Practical applications of POPS require large plasma compressions. These large compressions have been observed in particle simulations, although space charge neutralization remains a major issue.

  16. Oscillating edge-flames

    NASA Astrophysics Data System (ADS)

    Buckmaster, J.; Zhang, Yi

    1999-09-01

    It has been known for some years that when a near-limit flame spreads over a liquid pool of fuel, the edge of the flame can oscillate. It is also known that when a near-asphyxiated candle-flame burns in zero gravity, the edge of the (hemispherical) flame can oscillate violently prior to extinction. We propose that these oscillations are nothing more than a manifestation of the large Lewis number instability well known in chemical reactor studies and in combustion studies, one that is exacerbated by heat losses. As evidence of this we examine an edge-flame confined within a fuel-supply boundary and an oxygen-supply boundary, anchored by a discontinuity in data at the fuel-supply boundary. We show that when the Lewis number of the fuel is 2, and the Lewis number of the oxidizer is 1, oscillations of the edge occur when the Damköhler number is reduced below a critical value. During a single oscillation period there is a short premixed propagation stage and a long diffusion stage, behaviour that has been observed in flame spread experiments. Oscillations do not occur when both Lewis numbers are equal to 1.

  17. Rocket Engine Oscillation Diagnostics

    NASA Technical Reports Server (NTRS)

    Nesman, Tom; Turner, James E. (Technical Monitor)

    2002-01-01

    Rocket engine oscillating data can reveal many physical phenomena ranging from unsteady flow and acoustics to rotordynamics and structural dynamics. Because of this, engine diagnostics based on oscillation data should employ both signal analysis and physical modeling. This paper describes an approach to rocket engine oscillation diagnostics, types of problems encountered, and example problems solved. Determination of design guidelines and environments (or loads) from oscillating phenomena is required during initial stages of rocket engine design, while the additional tasks of health monitoring, incipient failure detection, and anomaly diagnostics occur during engine development and operation. Oscillations in rocket engines are typically related to flow driven acoustics, flow excited structures, or rotational forces. Additional sources of oscillatory energy are combustion and cavitation. Included in the example problems is a sampling of signal analysis tools employed in diagnostics. The rocket engine hardware includes combustion devices, valves, turbopumps, and ducts. Simple models of an oscillating fluid system or structure can be constructed to estimate pertinent dynamic parameters governing the unsteady behavior of engine systems or components. In the example problems it is shown that simple physical modeling when combined with signal analysis can be successfully employed to diagnose complex rocket engine oscillatory phenomena.

  18. First-Principles Design of a Deep-Ultraviolet Nonlinear-Optical Crystal from KBe2BO3F2 to NH4Be2BO3F2.

    PubMed

    Kang, Lei; Luo, Siyang; Peng, Guang; Ye, Ning; Wu, Yicheng; Chen, Chuangtian; Lin, Zheshuai

    2015-11-16

    KBe2BO3F2 (KBBF) is so far the sole nonlinear-optical (NLO) material that can be practically applied in the deep-ultraviolet (DUV) region. For the purpose of overcoming its layering tendency in crystal growth, herein a computer-assisted material design system is employed to design a new KBBF analogue, ammonia beryllium fluoroborate (NH4Be2BO3F2, ABBF). The first-principles calculations demonstrate that ABBF possesses NLO properties very close to those of KBBF, thus exhibiting good DUV NLO capability. Moreover, owing to the relatively strong chemical binding between layers, ABBF would have a better growth habit compared with KBBF. Upon synthesis, ABBF would be a very promising DUV NLO material. PMID:26509702

  19. Generation of oscillating gene regulatory network motifs

    NASA Astrophysics Data System (ADS)

    van Dorp, M.; Lannoo, B.; Carlon, E.

    2013-07-01

    Using an improved version of an evolutionary algorithm originally proposed by François and Hakim [Proc. Natl. Acad. Sci. USAPNASA60027-842410.1073/pnas.0304532101 101, 580 (2004)], we generated small gene regulatory networks in which the concentration of a target protein oscillates in time. These networks may serve as candidates for oscillatory modules to be found in larger regulatory networks and protein interaction networks. The algorithm was run for 105 times to produce a large set of oscillating modules, which were systematically classified and analyzed. The robustness of the oscillations against variations of the kinetic rates was also determined, to filter out the least robust cases. Furthermore, we show that the set of evolved networks can serve as a database of models whose behavior can be compared to experimentally observed oscillations. The algorithm found three smallest (core) oscillators in which nonlinearities and number of components are minimal. Two of those are two-gene modules: the mixed feedback loop, already discussed in the literature, and an autorepressed gene coupled with a heterodimer. The third one is a single gene module which is competitively regulated by a monomer and a dimer. The evolutionary algorithm also generated larger oscillating networks, which are in part extensions of the three core modules and in part genuinely new modules. The latter includes oscillators which do not rely on feedback induced by transcription factors, but are purely of post-transcriptional type. Analysis of post-transcriptional mechanisms of oscillation may provide useful information for circadian clock research, as recent experiments showed that circadian rhythms are maintained even in the absence of transcription.

  20. Understanding Oscillations of the Geological Carbon Cycle

    NASA Astrophysics Data System (ADS)

    Bachan, A.; Payne, J.; Saltzman, M.; Thomas, E.; Kump, L. R.

    2015-12-01

    The geological cycling of carbon ties together the sedimentary reservoirs with Earth's biosphere and climate. Perturbations to this coupled system are recorded in the carbon isotopic composition of marine limestones (δ13Ccarb). In the past decade numerous intervals of large-amplitude oscillations in δ13Ccarbhave been identified, with a variety of explanations proposed for individual events. Yet, when data spanning the past ~1 Ga are viewed as a whole, it is clear that large-scale oscillations are a common feature of the carbon isotopic record. The ubiquity of oscillations suggests that they may share a single origin rather than having many disparate causes. Here we present a simple two-box model of the geological carbon cycle exhibiting such oscillations: the Carbon-Cycle Oscillator. Analogous to a damped mass-spring system, the burial fluxes of carbonate and phosphate in the model act like friction, whereas P supply and Corg burial act like the restoring force of the spring. When the sensitivities of P supply and Corg burial to the sizes of the C and P reservoirs, respectively, increase above a critical threshold, the model exhibits oscillations upon perturbation. We suggest that intervals with large oscillations in bulk ocean-atmosphere δ13C are characterized by a greater sensitivity of the C:P burial-ratio and ALK:P weathering-ratio to the state of the ocean-atmosphere carbon pool. In addition, moderating of the slope of that dependence in general can account for the observed decrease in the amplitude of oscillations over the past billion years. We hypothesize that factors with a unidirectional trajectory during Earth history (e.g. increased oxygenation of the deep ocean, and evolution of pelagic calcifiers) led to a decrease in the Earth System's gain and increase in its resilience over geologic time, even in the face of continuing perturbations from the solid Earth and extraterrestrial realms.

  1. The active-bridge oscillator

    SciTech Connect

    Wessendorf, K.O.

    1998-07-01

    This paper describes the Active-Bridge Oscillator (ABO), a new concept in high-stability oscillator design. The ABO is ab ridge-type oscillator design that is easly to design and overcomes many of the operational and design difficulties associated with standard bridge oscillator designs. The ABO will oscillate with a very stable output amplitude over a wide range of operating conditions without the use of an automatic-level-control (ALC). A standard bridge oscillator design requires an ALC to maintain the desired amplitude of oscillation. for this and other reasons, bridge oscilaltors are not used in mainstream designs. Bridge oscillators are generally relegated to relatively low-volume, high-performance applications. The Colpitts and Pierce designs are the most popular oscillators but are typically less stable than a bridge-type oscillator.

  2. Neutrino Oscillation Physics

    SciTech Connect

    Kayser, Boris

    2012-06-01

    To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures. Neutrinos and photons are by far the most abundant elementary particles in the universe. Thus, if we would like to comprehend the universe, we must understand the neutrinos. Of course, studying the neutrinos is challenging, since the only known forces through which these electrically-neutral leptons interact are the weak force and gravity. Consequently, interactions of neutrinos in a detector are very rare events, so that very large detectors and intense neutrino sources are needed to make experiments feasible. Nevertheless, we have confirmed that the weak interactions of neutrinos are correctly described by the Standard Model (SM) of elementary particle physics. Moreover, in the last 14 years, we have discovered that neutrinos have nonzero masses, and that leptons mix. These discoveries have been based on the observation that neutrinos can change from one 'flavor' to another - the phenomenon known as neutrino oscillation. We shall explain the physics of neutrino oscillation, deriving the probability of oscillation in a new way. We shall also provide a very brief guide to references that can be used to study some major neutrino-physics topics other than neutrino oscillation.

  3. Intrinsic quantum anomalous Hall effect in the kagome lattice Cs2LiMn3F12

    DOE PAGESBeta

    Xu, Gang; Lian, Biao; Zhang, Shou -Cheng

    2015-10-27

    In a kagome lattice, the time reversal symmetry can be broken by a staggered magnetic flux emerging from ferromagnetic ordering and intrinsic spin-orbit coupling, leading to several well-separated nontrivial Chern bands and intrinsic quantum anomalous Hall effect. Based on this idea and ab initio calculations, we propose the realization of the intrinsic quantum anomalous Hall effect in the single layer Cs2Mn3F12 kagome lattice and on the (001) surface of a Cs2LiMn3F12 single crystal by modifying the carrier coverage on it, where the band gap is around 20 meV. Furthermore, a simplified tight binding model based on the in-plane ddσ antibondingmore » states is constructed to understand the topological band structures of the system.« less

  4. Intrinsic Quantum Anomalous Hall Effect in the Kagome Lattice Cs2 LiMn3 F12

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Lian, Biao; Zhang, Shou-Cheng; Zhang's Group Team

    In a kagome lattice, the time reversal symmetry can be broken by a staggered magnetic flux emerging from the ferromagnetic ordering and intrinsic spin-orbit coupling, leading to several well-separated nontrivial Chern bands and intrinsic quantum anomalous Hall effect. Based on this idea and ab initio calculations, we propose the realization of the intrinsic quantum anomalous Hall effect in the single layer Cs2Mn3F12 kagome lattice and on the (001) surface of a Cs2LiMn3F12 single crystal by modifying the carrier coverage on it, where the band gap is around 20 meV. Moreover, a simplified tight binding model based on the inplane dd σ antibonding states is constructed to understand the topological band structures of the system.

  5. Intrinsic Quantum Anomalous Hall Effect in the Kagome Lattice Cs2 LiMn3 F12

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Lian, Biao; Zhang, Shou-Cheng

    2015-10-01

    In a kagome lattice, the time reversal symmetry can be broken by a staggered magnetic flux emerging from ferromagnetic ordering and intrinsic spin-orbit coupling, leading to several well-separated nontrivial Chern bands and intrinsic quantum anomalous Hall effect. Based on this idea and ab initio calculations, we propose the realization of the intrinsic quantum anomalous Hall effect in the single layer Cs2Mn3F12 kagome lattice and on the (001) surface of a Cs2LiMn3F12 single crystal by modifying the carrier coverage on it, where the band gap is around 20 meV. Moreover, a simplified tight binding model based on the in-plane d d σ antibonding states is constructed to understand the topological band structures of the system.

  6. Construction of Tunnel Diode Oscillator for AC Impedance Measurement

    NASA Astrophysics Data System (ADS)

    Shin, J. H.; Kim, E.

    2014-03-01

    We construct a tunnel diode oscillator (TDO) to study electromagnetic response of a superconducting thin film. Highly sensitive tunnel diode oscillators allow us to detect extremely small changes in electromagnetic properties such as dielectric constant, ac magnetic susceptibility and magnetoresistance. A tunnel diode oscillator is a self-resonant oscillator of which resonance frequency is primarily determined by capacitance and inductance of a resonator. Amplitude of the signal depends on the quality factor of the resonator. The change in the impedance of the sample electromagnetic coupled to one of inductors in the resonator alters impedance of the inductor, and leads to the shift in the resonance frequency and the change of the amplitude.

  7. A sensitive and specific histopathologic prognostic marker for H3F3A K27M mutant pediatric glioblastomas.

    PubMed

    Venneti, Sriram; Santi, Mariarita; Felicella, Michelle Madden; Yarilin, Dmitry; Phillips, Joanna J; Sullivan, Lisa M; Martinez, Daniel; Perry, Arie; Lewis, Peter W; Thompson, Craig B; Judkins, Alexander R

    2014-11-01

    Pediatric glioblastomas (GBM) are highly aggressive and lethal tumors. Recent sequencing studies have shown that ~30 % of pediatric GBM and ~80 % of diffuse intrinsic pontine gliomas show K27M mutations in the H3F3A gene, a variant encoding histone H3.3. H3F3A K27M mutations lead to global reduction in H3K27me3. Our goal was to develop biomarkers for the histopathologic detection of these tumors. Therefore, we evaluated the utility of measuring H3K27me3 global reduction as a histopathologic and prognostic biomarker and tested an antibody directed specifically against the H3.3 K27M mutation in 290 samples. The study cohort included 203 pediatric (including 38 pediatric high-grade astrocytomas) and 38 adult brain tumors of various subtypes and grades and 49 non-neoplastic reactive brain tissues. Detection of H3.3 K27M by immunohistochemistry showed 100 % sensitivity and specificity and was superior to global reduction in H3K27me3 as a biomarker in diagnosing H3F3A K27M mutations. Moreover, cases that stained positive for H3.3 K27M showed a significantly poor prognosis compared to corresponding negative tumors. These results suggest that immunohistochemical detection of H3.3 K27M is a sensitive and specific surrogate for the H3F3A K27M mutation and defines a prognostically poor subset of pediatric GBM. PMID:25200322

  8. Beta oscillations in the parkinsonian primate: Similar oscillations across different populations.

    PubMed

    Matzner, Ayala; Moran, Anan; Erez, Yaara; Tischler, Hadass; Bar-Gad, Izhar

    2016-09-01

    Parkinson's disease (PD) is characterized by excessive beta band oscillations (BBO) in neuronal spiking activity across basal ganglia (BG) nuclei. High frequency stimulation of the subthalamic nucleus, an effective treatment for PD, suppresses these oscillations. There is still a heated debate on the origin and propagation of BBO and their association to clinical symptoms. The key prerequisite in addressing these issues is to obtain an accurate estimation of the subpopulation of oscillatory neurons and the magnitude of their oscillations. Studies have shown that neurons in different BG nuclei vary dramatically in the magnitude of their oscillations. However, the stochastic nature of neuronal activity subsamples the oscillatory neuronal rate functions, thus causing standard spectral analysis methods to be dramatically biased by biological and experimental factors such as variations in the neuronal firing rate across BG nuclei. In order to overcome these biases, and directly analyze the expression of BBO within BG nuclei, we used a novel objective method, the modulation index. This method reveals that unlike previous spectral results, individual neurons in the different nuclei display similar magnitudes of oscillations, whereas only the size of the oscillatory subpopulation varies between nuclei. During stimulation, the magnitude of the BBO does not change but the fraction of oscillatory neurons decreases in the globus pallidus internus, leading to a significant change in BG output. This non-biased oscillation quantification thus enables the reconstruction of oscillations at the single neuron and nuclei population levels, and calls for a reassessment of the role of BBO during PD. PMID:27083136

  9. A New Neutrino Oscillation

    SciTech Connect

    Parke, Stephen J.; /Fermilab

    2011-07-01

    Starting in the late 1960s, neutrino detectors began to see signs that neutrinos, now known to come in the flavors electron ({nu}{sub e}), muon ({nu}{sub {mu}}), and tau ({nu}{sub {tau}}), could transform from one flavor to another. The findings implied that neutrinos must have mass, since massless particles travel at the speed of light and their clocks, so to speak, don't tick, thus they cannot change. What has since been discovered is that neutrinos oscillate at two distinct scales, 500 km/GeV and 15,000 km/GeV, which are defined by the baseline (L) of the experiment (the distance the neutrino travels) divided by the neutrino energy (E). Neutrinos of one flavor can oscillate into neutrinos of another flavor at both L/E scales, but the amplitude of these oscillations is different for the two scales and depends on the initial and final flavor of the neutrinos. The neutrino states that propogate unchanged in time, the mass eigenstates {nu}1, {nu}2, {nu}3, are quantum mechanical mixtures of the electron, muon, and tau neutrino flavors, and the fraction of each flavor in a given mass eigenstate is controlled by three mixing angles and a complex phase. Two of these mixing angles are known with reasonable precision. An upper bound exists for the third angle, called {theta}{sub 13}, which controls the size of the muon neutrino to electron neutrino oscillation at an L/E of 500 km/GeV. The phase is completely unknown. The existence of this phase has important implications for the asymmetry between matter and antimatter we observe in the universe today. Experiments around the world have steadily assembled this picture of neutrino oscillation, but evidence of muon neutrino to electron neutrino oscillation at 500 km/GeV has remained elusive. Now, a paper from the T2K (Tokai to Kamioka) experiment in Japan, reports the first possible observation of muon neutrinos oscillating into electron neutrinos at 500 km/GeV. They see 6 candidate signal events, above an expected background

  10. Forced spaser oscillations

    NASA Astrophysics Data System (ADS)

    Lisyansky, Alexander A.; Andrianov, Eugeney S.; Dorofeenko, Alexander V.; Pukhov, Alexander A.; Vinogradov, Alexey P.

    2012-10-01

    We study oscillations of a spaser driven by an external optical wave. When the frequency of the external field is shifted from the frequency of an autonomous spaser, the spaser exhibits stochastic oscillations at low field intensity. The plasmon oscillations lock to the frequency of the external field only when the field amplitude exceeds a threshold value. We find a region of external field amplitude and the frequency detuning (the Arnold tongue) for which the spaser becomes synchronized with the external wave. We obtain the conditions upon the amplitude and frequency of the external field (the curve of compensation) at which the spaser's dipole moment oscillates with a phase shift of π relatively to the external wave. For these values of the amplitude and frequency, the loss in the metal nanoparticles within the spaser is exactly compensated for by the gain. It is expected that if these conditions are not satisfied, then due to loss or gain of energy, the amplitude of the wave travelling along the system of spasers either tends to the curve of compensation or leave the Arnold tongue. We also consider cooperative phenomena showing that in a chain of interacting spasers, depending on the values of the coupling constants, either all spasers oscillate in phase or a nonlinear autowave travels in the system. In the latter scenario, the traveling wave is harmonic, unlike excitations in other nonlinear systems. Due to the nonlinear nature of the system, any initial distribution of spaser states evolves into one of these steady states.

  11. Oscillations of soap bubbles

    NASA Astrophysics Data System (ADS)

    Kornek, U.; Müller, F.; Harth, K.; Hahn, A.; Ganesan, S.; Tobiska, L.; Stannarius, R.

    2010-07-01

    Oscillations of droplets or bubbles of a confined fluid in a fluid environment are found in various situations in everyday life, in technological processing and in natural phenomena on different length scales. Air bubbles in liquids or liquid droplets in air are well-known examples. Soap bubbles represent a particularly simple, beautiful and attractive system to study the dynamics of a closed gas volume embedded in the same or a different gas. Their dynamics is governed by the densities and viscosities of the gases and by the film tension. Dynamic equations describing their oscillations under simplifying assumptions have been well known since the beginning of the 20th century. Both analytical description and numerical modeling have made considerable progress since then, but quantitative experiments have been lacking so far. On the other hand, a soap bubble represents an easily manageable paradigm for the study of oscillations of fluid spheres. We use a technique to create axisymmetric initial non-equilibrium states, and we observe damped oscillations into equilibrium by means of a fast video camera. Symmetries of the oscillations, frequencies and damping rates of the eigenmodes as well as the coupling of modes are analyzed. They are compared to analytical models from the literature and to numerical calculations from the literature and this work.

  12. The Kramers Oscillator Revisited

    NASA Astrophysics Data System (ADS)

    Arnold, Ludwig; Imkeller, Peter

    In their 1993 paper [14], Schimansky-Geier and Herze1 discovered numerically that the Kramers oscillator (which is identical with the Duffing oscillator forced by additive white noise) has a positive top Lyapunov exponent in the low damping regime. In this paper, we study the Kramers oscillator from the point of view of random dynamical systems. In particular, we confirm the findings in the paper [14] about the Lyapunov exponent by performing more precise simulations, revealing that the Lyapunov exponent is positive up to a critical value of the damping, from which on it remains negative. We then show that the Kramers oscillator has a global random attractor which in the stable regime (large damping) is just a random point and in the unstable regime (small damping) has very complicated geometrical structure. In the lat-ter case the invariant measure supported by the attractor is a Sinai-Ruelle-Bowen measure with positive entropy. The Kramers oscillator hence undergoes a stochastic bifurcation at the critical value of the damping Parameter.

  13. Oscillations following periodic reinforcement.

    PubMed

    Monteiro, Tiago; Machado, Armando

    2009-06-01

    Three experiments examined behavior in extinction following periodic reinforcement. During the first phase of Experiment 1, four groups of pigeons were exposed to fixed interval (FI 16s or FI 48s) or variable interval (VI 16s or VI 48s) reinforcement schedules. Next, during the second phase, each session started with reinforcement trials and ended with an extinction segment. Experiment 2 was similar except that the extinction segment was considerably longer. Experiment 3 replaced the FI schedules with a peak procedure, with FI trials interspersed with non-food peak interval (PI) trials that were four times longer. One group of pigeons was exposed to FI 20s PI 80s trials, and another to FI 40s PI 160s trials. Results showed that, during the extinction segment, most pigeons trained with FI schedules, but not with VI schedules, displayed pause-peck oscillations with a period close to, but slightly greater than the FI parameter. These oscillations did not start immediately after the onset of extinction. Comparing the oscillations from Experiments 1 and 2 suggested that the alternation of reconditioning and re-extinction increases the reliability and earlier onset of the oscillations. In Experiment 3 the pigeons exhibited well-defined pause-peck cycles since the onset of extinction. These cycles had periods close to twice the value of the FI and lasted for long intervals of time. We discuss some hypotheses concerning the processes underlying behavioral oscillations following periodic reinforcement. PMID:18992793

  14. Combustor oscillation pressure stabilizer

    SciTech Connect

    Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.; Cully, S.R.; Addis, R.E.

    1996-12-31

    In accordance with the objective of the present invention, the active control of unsteady combustion induced oscillations in a combustion chamber fired by a suitable fuel and oxidizer mixture, such as a hydrocarbon fuel and air mixture, is provided by restructuring and moving the position of the main flame front and thereby increasing the transport time and displacing the pressure wave further away from the in-phase relationship with the periodic heat release. The restructuring and repositioning of the main flame are achieved by utilizing a pilot flame which is pulsed at a predetermined frequency corresponding to less than about one-half the frequency of the combustion oscillation frequency with the duration of each pulse being sufficient to produce adequate secondary thermal energy to restructure the main flame and thereby decouple the heat release from the acoustic coupling so as to lead to a reduction in the dynamic pressure amplitude. The pulsating pilot flame produces a relatively small and intermittently existing flame front in the combustion zone that is separate from the oscillating main flame front but which provides the thermal energy necessary to effectively reposition the location of the oscillating main flame front out of the region in the combustion zone where the acoustic coupling can occur with the main flame and thereby effectively altering the oscillation-causing phase relationship with the heat of combustion.

  15. Digital numerically controlled oscillator

    NASA Technical Reports Server (NTRS)

    Cellier, A.; Huey, D. C.; Ma, L. N. (Inventor)

    1980-01-01

    The frequency and phase of an output signal from an oscillator circuit are controlled with accuracy by a digital input word. Positive and negative alterations in output frequency are both provided for by translating all values of input words so that they are positive. The oscillator reference frequency is corrected only in one direction, by adding phase to the output frequency of the oscillator. The input control word is translated to a single algebraic sign and the digital 1 is added thereto. The translated input control word is then accumulated. A reference clock signal having a frequency at an integer multiple of the desired frequency of the output signal is generated. The accumulated control word is then compared with a threshold level. The output signal is adjusted in a single direction by dividing the frequency of the reference clock signal by a first integer or by an integer different from the first integer.

  16. The Fastest Quasiperiodic Oscillations

    NASA Astrophysics Data System (ADS)

    Kaaret, Philip

    Quasi-periodic oscillations (QPOs) at frequencies near 1000 Hz have been detected from a umber of neutron star x-ray binaries using RXTE. These fast oscillations are likely associated with rbital motion very close to the neutron star and and, thus, give us information about the behavior of the accretion disk in the strong gravitational field near the neutron star. The oscillation frequencies can also be used to place constraints on the properties of the neutron stars with the highest detected frequencies being the most constraining. We propose TOOs observations of selected neutron star x-ray binaries when found to be in states likely to produce kHz QPOs with frequencies exceeding 1200 Hz.

  17. Magnetic vortex oscillators

    NASA Astrophysics Data System (ADS)

    Hrkac, Gino; Keatley, Paul S.; Bryan, Matthew T.; Butler, Keith

    2015-11-01

    The magnetic vortex has sparked the interest of the academic and industrial communities over the last few decades. From their discovery in the 1970s for bubble memory devices to their modern application as radio frequency oscillators, magnetic vortices have been adopted to modern telecommunication and sensor applications. Basic properties of vortex structures in the static and dynamic regime, from a theoretical and experimental point of view, are presented as well as their application in spin torque driven nano-pillar and magnetic tunnel junction devices. Single vortex excitations and phase locking phenomena of coupled oscillators are discussed with an outlook of vortex oscillators in magnetic hybrid structures with imprinted domain confinement and dynamic encryption devices.

  18. Gamma Oscillation in Schizophrenia

    PubMed Central

    O'Donnell, Brian F.; Youn, Soyoung; Kwon, Jun Soo

    2011-01-01

    Dysfunctional neural circuitry has been found to be involved in abnormalities of perception and cognition in patients with schizophrenia. Gamma oscillations are essential for integrating information within neural circuits and have therefore been associated with many perceptual and cognitive processes in healthy human subjects and animals. This review presents an overview of the neural basis of gamma oscillations and the abnormalities in the GABAergic interneuronal system thought to be responsible for gamma-range deficits in schizophrenia. We also review studies of gamma activity in sensory and cognitive processes, including auditory steady state response, attention, object representation, and working memory, in animals, healthy humans and patients with schizophrenia. PMID:22216037

  19. Micromechanical Oscillating Mass Balance

    NASA Technical Reports Server (NTRS)

    Altemir, David A. (Inventor)

    1997-01-01

    A micromechanical oscillating mass balance and method adapted for measuring minute quantities of material deposited at a selected location, such as during a vapor deposition process. The invention comprises a vibratory composite beam which includes a dielectric layer sandwiched between two conductive layers. The beam is positioned in a magnetic field. An alternating current passes through one conductive layers, the beam oscillates, inducing an output current in the second conductive layer, which is analyzed to determine the resonant frequency of the beam. As material is deposited on the beam, the mass of the beam increases and the resonant frequency of the beam shifts, and the mass added is determined.

  20. Search for free neutron-antineutron oscillations

    NASA Astrophysics Data System (ADS)

    Bressi, G.; Calligarich, E.; Cambiaghi, M.; Dolfini, R.; Genoni, M.; Berzolari, A. Gigli; Lanza, A.; Liguori, G.; Mauri, F.; Piazzoli, A.; Ratti, S. P.; Torre, P.; Bini, C.; Conversi, M.; de Zorzi, G.; Gauzzi, P.; Massa, F.; Zanello, D.; Cardarelli, R.; Santonico, R.; Scannicchio, D.; Terrani, M.

    1989-06-01

    A search for free neutron-antineutron oscillations has been carried out at the Pavia Triga Mark II research reactor. A thin carbon target is crossed by a beam of thermal neutrons propagating in a 18.5 m long channel where the earth magnetic field is attenuated by a factor of 50. The total neutron current through the target is 3.2×1010 n/s. Possible antineutron annihilations are identified by a large track detector surrounding the target. A lower limit on the oscillation time of 4.7×105 s (90% C.L.) has been reached.

  1. Forced oscillations with linear and nonlinear damping

    NASA Astrophysics Data System (ADS)

    Li, Aijun; Ma, Li; Keene, David; Klingel, Joshua; Payne, Marvin; Wang, Xiao-jun

    2016-01-01

    A general solution is derived for the differential equations of forced oscillatory motion with both linear damping ( ˜v ) and nonlinear damping ( ˜v2 ). Experiments with forced oscillators are performed using a flat metal plate with a drag force due to eddy currents and a flat piece of stiffened cardboard with a drag force due to air resistance serving as the linear and nonlinear damping, respectively. Resonance of forced oscillations for different damping forces and quality factors is demonstrated. The experimental measurements and theoretical calculations are in good agreement, and damping constants are determined.

  2. The Global Oscillation Network Group (GONG) Project

    PubMed

    Harvey; Hill; Hubbard; Kennedy; Leibacher; Pintar; Gilman; Noyes; Title; Toomre; Ulrich; Bhatnagar; Kennewell; Marquette; Patron; Saa; Yasukawa

    1996-05-31

    Helioseismology requires nearly continuous observations of the oscillations of the solar surface for long periods of time in order to obtain precise measurements of the sun's normal modes of oscillation. The GONG project acquires velocity images from a network of six identical instruments distributed around the world. The GONG network began full operation in October 1995. It has achieved a duty cycle of 89 percent and reduced the magnitude of spectral artifacts by a factor of 280 in power, compared with single-site observations. The instrumental noise is less than the observed solar background. PMID:8662455

  3. CARCINOGENICITY OF BROMODICHLOROMETHANE ADMINISTERED IN DRINKING WATER TO THE MALE F344/N RAT AND B6C3F, MOUSE

    EPA Science Inventory

    CARCINOGENICITY OF BROMODICHLOROMETHANE ADMINISTERED IN DRINKING WATER TO THE MALE F344/N RAT AND B6C3F1 MOUSE.

    Bromodichloromethane (BDCM) has been shown to produce kidney and large bowel tumors in both male and female F344/N rats, kidney tumors in male B6C3F 1 mice and ...

  4. Coupled opto-electronic oscillator

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor); Maleki, Lute (Inventor)

    1999-01-01

    A coupled opto-electronic oscillator that directly couples a laser oscillation with an electronic oscillation to simultaneously achieve a stable RF oscillation at a high frequency and ultra-short optical pulsation by mode locking with a high repetition rate and stability. Single-mode selection can be achieved even with a very long opto-electronic loop. A multimode laser can be used to pump the electronic oscillation, resulting in a high operation efficiency. The optical and the RF oscillations are correlated to each other.

  5. Nanoparticle Oscillations and Fronts

    SciTech Connect

    Lagzi, Istvan; Kowalczyk, Bartlomiej; Wang, Dawei; Grzybowski, Bartosz A.

    2010-09-30

    Chemical oscillations can be coupled to the dynamic self-assembly of nanoparticles. Periodic pH changes translate into protonation and deprotonation of the ligands that stabilize the nanoparticles, thus altering repulsive and attractive interparticle forces. In a continuous stirred-tank reactor, rhythmic aggregation and dispersion is observed; in spatially distributed media, propagation of particle aggregation fronts is seen.

  6. Voltage-Controlled Oscillator

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Integrated Component Systems, Inc. incorporated information from a NASA Tech Briefs article into a voltage-controlled oscillator it designed for a customer. The company then applied the technology to its series of phase-locked loop synthesizers, which offer superior phase noise performance.

  7. Coupled Oscillators with Chemotaxis

    NASA Astrophysics Data System (ADS)

    Sawai, Satoshi; Aizawa, Yoji

    1998-08-01

    A simple coupled oscillator system with chemotaxis is introducedto study morphogenesis of cellular slime molds. The modelsuccessfuly explains the migration of pseudoplasmodium which hasbeen experimentally predicted to be lead by cells with higherintrinsic frequencies. Results obtained predict that its velocityattains its maximum value in the interface region between totallocking and partial locking and also suggest possible rolesplayed by partial synchrony during multicellular development.

  8. Oscillating Reactions: Two Analogies

    ERIC Educational Resources Information Center

    Petruševski, Vladimir M.; Stojanovska, Marina I.; Šoptrajanov, Bojan T.

    2007-01-01

    Oscillating chemical reactions are truly spectacular phenomena, and demonstrations are always appreciated by the class. However, explaining such reactions to high school or first-year university students is problematic, because it may seem that no acceptable explanation is possible unless the students have profound knowledge of both physical…

  9. Relativistic harmonic oscillator revisited

    SciTech Connect

    Bars, Itzhak

    2009-02-15

    The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

  10. A simple violin oscillator

    NASA Technical Reports Server (NTRS)

    Jones, R. T.

    1976-01-01

    For acoustic tests the violin is driven laterally at the bridge by a small speaker of the type commonly found in pocket transistor radios. An audio oscillator excites the tone which is picked up by a sound level meter. Gross patterns of vibration modes are obtained by the Chladni method.

  11. Wein bridge oscillator circuit

    NASA Technical Reports Server (NTRS)

    Lipoma, P. C.

    1971-01-01

    Circuit with minimum number of components provides stable outputs of 2 to 8 volts at frequencies of .001 to 100 kHz. Oscillator exhibits low power consumption, portability, simplicity, and drive capability, it has application as loudspeaker tester and audible alarm, as well as in laboratory and test generators.

  12. Effects of Neutrino Decay on Oscillation Probabilities

    NASA Astrophysics Data System (ADS)

    Leonard, Kayla; de Gouvêa, André

    2016-01-01

    It is now well accepted that neutrinos oscillate as a quantum mechanical result of a misalignment between their mass-eigenstates and the flavor-eigenstates. We study neutrino decay—the idea that there may be new, light states that the three Standard Model flavors may be able to decay into. We consider what effects this neutrino decay would have on the observed oscillation probabilities.The Hamiltonian governs how the states change with time, so we use it to calculate an oscillation amplitude, and from that, the oscillation probability. We simplify the theoretical probabilities using results from experimental data, such as the neutrino mixing angles and mass differences. By exploring what values of the decay parameters are physically allowable, we can begin to understand just how large the decay parameters can be. We compare the probabilities in the case of no neutrino decay and in the case of maximum neutrino decay to determine how much of an effect neutrino decay could have on observations, and discuss the ability of future experiments to detect these differences.We also examine neutrino decay in the realm of CP invariance, and found that it is a new source of CP violation. Our work indicates that there is a difference in the oscillation probabilities between particle transitions and their corresponding antiparticle transitions. If neutrino decay were proven true, it could be an important factor in understanding leptogenesis and the particle-antiparticle asymmetry present in our Universe.

  13. Master oscillator stability requirements considerations

    SciTech Connect

    Schwarz, H.; Vancraeynest, J.

    1986-06-24

    This note attempts to point out some ideas about the required stability of the 476 MHz master oscillator, assuming that the phase noise of the oscillator is the only source of noise in the accelerator system.

  14. Orthogonal polynomials and deformed oscillators

    NASA Astrophysics Data System (ADS)

    Borzov, V. V.; Damaskinsky, E. V.

    2015-10-01

    In the example of the Fibonacci oscillator, we discuss the construction of oscillator-like systems associated with orthogonal polynomials. We also consider the question of the dimensions of the corresponding Lie algebras.

  15. Time Dependence of Joint Entropy of Oscillating Quantum Systems

    NASA Astrophysics Data System (ADS)

    Özcan, Özgür; Aktürk, Ethem; Sever, Ramazan

    2008-12-01

    The time dependent entropy (or Leipnik’s entropy) of harmonic and damped harmonic oscillator systems is studied by using time dependent wave function obtained by the Feynman path integral method. The Leipnik entropy and its envelope change as a function of time, angular frequency and damping factor. Our results for simple harmonic oscillator are in agreement with the literature. However, the joint entropy of damped harmonic oscillator shows remarkable discontinuity with time for certain values of damping factor. The envelope of the joint entropy curve increases with time monotonically. These results show the general properties of the envelope of the joint entropy curve for quantum systems.

  16. Ionization oscillations in Hall accelerators

    NASA Astrophysics Data System (ADS)

    Barral, S.; Peradzyński, Z.

    2010-01-01

    The underlying mechanism of low-frequency oscillations in Hall accelerators is investigated theoretically. It is shown that relaxation oscillations arise from a competition between avalanche ionization and the advective transport of the working gas. The model derived recovers the slow progression and fast recession of the ionization front. Analytical approximations of the shape of current pulses and of the oscillation frequency are provided for the case of large amplitude oscillations.

  17. Forced Oscillations for Hybrid Systems

    NASA Astrophysics Data System (ADS)

    Cheshankov, B.

    2009-11-01

    The hybrid system in the paper means a mechanical system which consists from two parts with different structure—a part with distributed parameters and a part with discrete parameters. More concrete the forced longitudinal oscillations of a rod connected with a simple oscillator are considered. The oscillations of the separate parts of the system are very well known. It turned out that the oscillations of this hybrid system propose some difficulties when investigating. The paper proposes an approach to overcome these difficulties.

  18. Transverse oscillations in coronal loops observed with TRACE

    NASA Astrophysics Data System (ADS)

    Schrijver, C. J.; Aschwanden, M. J.; De Pontieu, B.; Title, A. M.

    2001-12-01

    TRACE discovered transverse oscillations in coronal loops associated with a flare three years ago, and until recently only two such events were known. We have now identified a total of 17 events that trigger some form of loop oscillations. Oscillation periods are estimated to range over a factor of ~ 15, with most values between 2 and 7 min. The oscillations are excited by filament destabilizations or flares (in 6%\\ of the 255 flares inspected, ranging from about C3 to X2). Oscillations occur in loops that close within an active region, or in loops that connect an active region to a neighboring region or to a patch of strong flux in the quiet Sun. Some magnetic configurations are particularly prone to exhibit oscillations: two active regions showed two, and one region even three, distinct intervals with loop oscillations. The loop oscillations are not a resonance that builds up: oscillations in loops that are excited along their entire length are likely to be near the fundamental resonance mode because of that excitation profile, but asymmetrically excited oscillations clearly show propagating waves that are damped too quickly to build up a resonance, and some cases show multiple frequencies. We discuss evidence that all oscillating loops lie near magnetic separatrices that outline the large-scale topology of the field. Often the oscillations occur in conjunction with gradual adjustments in loop positions in response to the triggering event. We discuss the observations in the context of two models, and evaluate the contraints on coronal properties that can be deduced from them. >http://vestige.lmsal.com/TRACE/POD/TRACEoscillations.html

  19. Development of doxorubicin-induced chronic cardiotoxicity in the B6C3F{sub 1} mouse model

    SciTech Connect

    Desai, Varsha G.; Herman, Eugene H.; Moland, Carrie L.; Branham, William S.; Lewis, Sherry M.; Davis, Kelly J.; George, Nysia I.; Lee, Taewon; Kerr, Susan; Fuscoe, James C.

    2013-01-01

    Serum levels of cardiac troponins serve as biomarkers of myocardial injury. However, troponins are released into the serum only after damage to cardiac tissue has occurred. Here, we report development of a mouse model of doxorubicin (DOX)-induced chronic cardiotoxicity to aid in the identification of predictive biomarkers of early events of cardiac tissue injury. Male B6C3F{sub 1} mice were administered intravenous DOX at 3 mg/kg body weight, or an equivalent volume of saline, once a week for 4, 6, 8, 10, 12, and 14 weeks, resulting in cumulative DOX doses of 12, 18, 24, 30, 36, and 42 mg/kg, respectively. Mice were sacrificed a week following the last dose. A significant reduction in body weight gain was observed in mice following exposure to a weekly DOX dose for 1 week and longer compared to saline-treated controls. DOX treatment also resulted in declines in red blood cell count, hemoglobin level, and hematocrit compared to saline-treated controls after the 2nd weekly dose until the 8th and 9th doses, followed by a modest recovery. All DOX-treated mice had significant elevations in cardiac troponin T concentrations in plasma compared to saline-treated controls, indicating cardiac tissue injury. Also, a dose-related increase in the severity of cardiac lesions was seen in mice exposed to 24 mg/kg DOX and higher cumulative doses. Mice treated with cumulative DOX doses of 30 mg/kg and higher showed a significant decline in heart rate, suggesting drug-induced cardiac dysfunction. Altogether, these findings demonstrate the development of DOX-induced chronic cardiotoxicity in B6C3F{sub 1} mice. -- Highlights: ► 24 mg/kg was a cumulative cardiotoxic dose of doxorubicin in male B6C3F{sub 1} mice. ► Doxorubicin-induced hematological toxicity was in association with splenomegaly. ► Doxorubicin induced severe testicular toxicity in B6C3F{sub 1} male mice.

  20. Analysis of precision in chemical oscillators: implications for circadian clocks

    NASA Astrophysics Data System (ADS)

    d'Eysmond, Thomas; De Simone, Alessandro; Naef, Felix

    2013-10-01

    Biochemical reaction networks often exhibit spontaneous self-sustained oscillations. An example is the circadian oscillator that lies at the heart of daily rhythms in behavior and physiology in most organisms including humans. While the period of these oscillators evolved so that it resonates with the 24 h daily environmental cycles, the precision of the oscillator (quantified via the Q factor) is another relevant property of these cell-autonomous oscillators. Since this quantity can be measured in individual cells, it is of interest to better understand how this property behaves across mathematical models of these oscillators. Current theoretical schemes for computing the Q factors show limitations for both high-dimensional models and in the vicinity of Hopf bifurcations. Here, we derive low-noise approximations that lead to numerically stable schemes also in high-dimensional models. In addition, we generalize normal form reductions that are appropriate near Hopf bifurcations. Applying our approximations to two models of circadian clocks, we show that while the low-noise regime is faithfully recapitulated, increasing the level of noise leads to species-dependent precision. We emphasize that subcomponents of the oscillator gradually decouple from the core oscillator as noise increases, which allows us to identify the subnetworks responsible for robust rhythms.

  1. Myelotoxicity induced in female B6C3F1 mice by inhalation of methyl isocyanate

    SciTech Connect

    Hong, H.L.; Bucher, J.R.; Canipe, J.; Boorman, G.A.

    1987-06-01

    The effects of a 4-day inhalation exposure (6 hr/day) to 0, 1, and 3 ppm methyl isocyanate (MIC) on bone marrow parameters in female mice were examined at 5, 8, and 21 days following exposure. The MIC exposure was associated with myelotoxicity as evidenced by hypocellularity, suppression of pluripotent stem cells (CFU-S), granulocyte-macrophage progenitors (CFU-GM) and erythroid precursors (CFU-E) in both dose groups. Hematopoietic parameters returned to normal by 21 days in the 1 ppm dose group, but not in the 3 ppm dose group. This indicates that the alterations in the bone marrow parameters persist for a relatively long period at dose levels where there are little or no changes in body weight, clinical pathology, or immunological parameters, suggesting that the bone marrow may be a sensitive endpoint for MIC exposure in mice. MIC is a highly reactive chemical that appears to exert its effect directly on the lining epithelium of the nasal cavity and major airways; there was no histological evidence of a systemic effect. The pathogenesis of the bone marrow depression is unknown; however, there were chronic bronchitis and bronchial fibrosis in the 3 ppm dose group. One possible explanation is that the cell injury induced in the lung is associated with the release of inhibitory factors for hematopoiesis, as the rodent lung is a potent source of both stimulatory and inhibitory growth factors for bone marrow progenitor cells. A second possibility is that the thymic atrophy found in MIC-exposed mice might be related to myelotoxicity. The pathogenesis of myelotoxicity in MIC exposure and its relationship with pulmonary injury require further study.

  2. Advances in the development of piezoelectric quartz-crystal oscillators, hydrogen masers, and superconducting frequency standards

    NASA Technical Reports Server (NTRS)

    Suter, Joseph J.

    1988-01-01

    This paper describes recent research advances made in the development of radiation-hardened piezoelectric quartz oscillators, hydrogen masers, and superconducting oscillators, with emphasis placed on the principles involved in the operation of these oscillators and the factors affecting the operation. Particular attention is given to the radiation-susceptibility studies of quartz-crystal resonators, the hydrogen-maser relaxation process and noise sources, and low-phase-noise superconducting oscillators. Diagrams of these devices and performance graphs are included.

  3. The electrical soliton oscillator

    NASA Astrophysics Data System (ADS)

    Ricketts, David Shawn

    Solitons are a special class of pulse-shaped waves that propagate in nonlinear dispersive media while maintaining their spatial confinement. They are found throughout nature where the proper balance between nonlinearity and dispersion is achieved. Examples of the soliton phenomena include shallow water waves, vibrations in a nonlinear spring-mass lattice, acoustic waves in plasma, and optical pulses in fiber optic cable. In electronics, the nonlinear transmission line (NLTL) serves as a nonlinear dispersive medium that propagates voltage solitons. Electrical solitons on the NLTL have been actively investigated over the last 40 years, particularly in the microwave domain, for sharp pulse generation applications and for high-speed RF and microwave sampling applications. In these past studies the NLTL has been predominantly used as a 2-port system where a high-frequency input is required to generate a sharp soliton output through a transient process. One meaningful extension of the past 2-port NLTL works would be to construct a 1-port self-sustained electrical soliton oscillator by properly combining the NLTL with an amplifier (positive active feedback). Such an oscillator would self-start by growing from ambient noise to produce a train of periodic soliton pulses in steady-state, and hence would make a self-contained soliton generator not requiring an external high-frequency input. While such a circuit may offer a new direction in the field of electrical pulse generation, there has not been a robust electrical soliton oscillator reported to date to the best of our knowledge. In this thesis we introduce the first robust electrical soliton oscillator, which is able to self-generate a stable, periodic train of electrical solitons. This new oscillator is made possible by combining the NLTL with a unique nonlinear amplifier that is able to "tame" the unruly dynamics of the NLTL. The principle contribution of this thesis is the identification of the key instability

  4. Dark matter search results from the PICO-2L C$_3$F$_8$ bubble chamber

    SciTech Connect

    Amole, C.

    2015-06-11

    New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of < 3.5 × 10–10 and an alpha rejection factor of > 98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. Lastly, these data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.

  5. Comparison of Renal Amyloid and Hyaline Glomerulopathy in B6C3F1 Mice: An NTP Retrospective Study.

    PubMed

    Hoane, Jessica S; Johnson, Crystal L; Morrison, James P; Elmore, Susan A

    2016-07-01

    Due to potential misdiagnosis of hyaline glomerulopathy (HG) for amyloidosis, a retrospective study of B6C3F1 mice from the National Toxicology Program (NTP) archives was undertaken to determine whether HG had occurred in prior NTP studies and, if so, whether these 2 glomerular lesions could be routinely discriminated. Kidney slides from 7 amyloid-positive control mice, 2 HG-positive control mice, 3 normal or negative control mice, and 41 potential HG mice (with renal-only deposits previously diagnosed as amyloid) were evaluated using hematoxylin and eosin (H&E), periodic acid Schiff (PAS), Congo red (CR), and Masson's trichrome (MT) stains. Utilizing these techniques, HG was reliably distinguished from amyloidosis. All 41 potential HG mice had glomerular deposits histochemically inconsistent with amyloid; the deposits were PAS positive and CR negative. Four of the 41 mice were selected for transmission electron microscopy of the glomerular deposits; ultrastructurally, the deposits in these animals were consistent with HG and not amyloid. Our findings indicate that HG is a spontaneous lesion in B6C3F1 mice of low occurrence, is commonly misdiagnosed as amyloidosis, and is more likely than amyloid to cause glomerular deposits in mice without evidence of deposits in other tissues. Also, HG can be distinguished from amyloid on H&E evaluation; however, the distinction is improved with use of PAS or CR staining and/or ultraviolet evaluation. PMID:27000376

  6. Elevated oxidative stress in skin of B6C3F1 mice affects dermal exposure to metal working fluid.

    PubMed

    Shvedova, A A; Kisin, E; Kisin, J; Castranova, V; Kommineni, C

    2000-09-01

    Metal working fluids (MWFs) are widely used in industry for metal cutting, drilling, shaping, lubricating, and milling. Potential for dermal exposure to MWFs exists for a large number of men and women via aerosols and splashing during the machining operations. It has been reported earlier that occupational exposure to MWFs causes allergic and irritant contact dermatitis. Previously, we showed that dermal exposure of female and male B6C3F1 mice to 5% MWFs for 3 months resulted in accumulation of mast cells and elevation of histamine in the skin. Topical exposure to MWF also resulted in elevated oxidative stress in the liver of both sexes and the testes in males. The goal of this study was to evaluate the interaction between oxidative stress in the skin and topical application of MWF. Oxidative stress in skin ofB6C3F1 mice of both sexes was generated by intradermal injection ofthe hydrogen peroxide (H2O2) -producing enzyme, glucose oxidase with polyethylene glycol (GOD+PEG). In mice given GOD+PEG, topical treatment with MWF (200 microl, 30%, for 1, 3, or 7 days) resulted in a mixed inflammatory cell response, accumulation of peroxidative products, and reduction of GSH content in the skin. Such changes were not observed with MWF treatment alone. These data indicate that oxidative stress can enhance dermal inflammation caused by occupational exposure to MWF. PMID:11693944

  7. Laser-Atomic Oscillator

    NASA Astrophysics Data System (ADS)

    Jau, Yuan-Yu; Happer, William

    2008-05-01

    We report a newly developed technique, laser-atomic oscillator, for simultaneously generating stable optical and electrical modulations with a very few components. It requires only a semiconductor laser, a vapor cell, and a few optical components. No photodetector and electronic feedback are needed. In this new system, the ground-state hyperfine coherence of alkali-metal atoms is spontaneously generated. The modulated laser light with a spectrum of a small optical comb is automatically produced, and the spacing between the comb peaks is photonically locked to the hyperfine frequency. The charge carriers in the semiconductor laser are also modulated at the hyperfine frequency. Laser-atomic oscillator is purely optical. Its simple structure allows the system to be very compact. We believe this new technique will bring some advantages in the applications of atomic chronometry, atomic magnetometry, and generation of multi-coherent light.

  8. Oscillations of complex networks

    NASA Astrophysics Data System (ADS)

    Wang, Xingang; Lai, Ying-Cheng; Lai, Choy Heng

    2006-12-01

    A complex network processing information or physical flows is usually characterized by a number of macroscopic quantities such as the diameter and the betweenness centrality. An issue of significant theoretical and practical interest is how such quantities respond to sudden changes caused by attacks or disturbances in recoverable networks, i.e., functions of the affected nodes are only temporarily disabled or partially limited. By introducing a model to address this issue, we find that, for a finite-capacity network, perturbations can cause the network to oscillate persistently in the sense that the characterizing quantities vary periodically or randomly with time. We provide a theoretical estimate of the critical capacity-parameter value for the onset of the network oscillation. The finding is expected to have broad implications as it suggests that complex networks may be structurally highly dynamic.

  9. Stable local oscillator module.

    SciTech Connect

    Brocato, Robert Wesley

    2007-11-01

    This report gives a description of the development of a Stable Local Oscillator (StaLO) multi-chip module (MCM). It is a follow-on report to SAND2006-6414, Stable Local Oscillator Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. This report describes the development of an MCM-based version of the complete StaLO, fabricated on an alumina thick film hybrid substrate.

  10. JFET reflection oscillator

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (Inventor)

    1985-01-01

    A high frequency oscillator circuit is provided using a low cost junction type field effect transistor (T sub 1) with a tuned circuit connected to its gate. The frequency of operation is determined by the tuned circuit and the capacitance reflected from the source to the gate. The transistor is matched to the frequency of operation so that this frequency falls within the roll-off portion of the transistor's transconductance verses frequency curve, preferably somewhat above the 3 db point in frequency. Phase shift necessary to sustain oscillation occurs due to the operation of the transistor in the roll-off portion of the curve and the addition of a phase shifting network (R sub 1, C sub 1) at the source.

  11. Phase chaos in coupled oscillators.

    PubMed

    Popovych, Oleksandr V; Maistrenko, Yuri L; Tass, Peter A

    2005-06-01

    A complex high-dimensional chaotic behavior, phase chaos, is found in the finite-dimensional Kuramoto model of coupled phase oscillators. This type of chaos is characterized by half of the spectrum of Lyapunov exponents being positive and the Lyapunov dimension equaling almost the total system dimension. Intriguingly, the strongest phase chaos occurs for intermediate-size ensembles. Phase chaos is a common property of networks of oscillators of very different natures, such as phase oscillators, limit-cycle oscillators, and chaotic oscillators, e.g., Rössler systems. PMID:16089804

  12. Phase chaos in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Popovych, Oleksandr V.; Maistrenko, Yuri L.; Tass, Peter A.

    2005-06-01

    A complex high-dimensional chaotic behavior, phase chaos, is found in the finite-dimensional Kuramoto model of coupled phase oscillators. This type of chaos is characterized by half of the spectrum of Lyapunov exponents being positive and the Lyapunov dimension equaling almost the total system dimension. Intriguingly, the strongest phase chaos occurs for intermediate-size ensembles. Phase chaos is a common property of networks of oscillators of very different natures, such as phase oscillators, limit-cycle oscillators, and chaotic oscillators, e.g., Rössler systems.

  13. Covariant deformed oscillator algebras

    NASA Technical Reports Server (NTRS)

    Quesne, Christiane

    1995-01-01

    The general form and associativity conditions of deformed oscillator algebras are reviewed. It is shown how the latter can be fulfilled in terms of a solution of the Yang-Baxter equation when this solution has three distinct eigenvalues and satisfies a Birman-Wenzl-Murakami condition. As an example, an SU(sub q)(n) x SU(sub q)(m)-covariant q-bosonic algebra is discussed in some detail.

  14. Quantifying Spike Train Oscillations: Biases, Distortions and Solutions

    PubMed Central

    Matzner, Ayala; Bar-Gad, Izhar

    2015-01-01

    Estimation of the power spectrum is a common method for identifying oscillatory changes in neuronal activity. However, the stochastic nature of neuronal activity leads to severe biases in the estimation of these oscillations in single unit spike trains. Different biological and experimental factors cause the spike train to differentially reflect its underlying oscillatory rate function. We analyzed the effect of factors, such as the mean firing rate and the recording duration, on the detectability of oscillations and their significance, and tested these theoretical results on experimental data recorded in Parkinsonian non-human primates. The effect of these factors is dramatic, such that in some conditions, the detection of existing oscillations is impossible. Moreover, these biases impede the comparison of oscillations across brain regions, neuronal types, behavioral states and separate recordings with different underlying parameters, and lead inevitably to a gross misinterpretation of experimental results. We introduce a novel objective measure, the "modulation index", which overcomes these biases, and enables reliable detection of oscillations from spike trains and a direct estimation of the oscillation magnitude. The modulation index detects a high percentage of oscillations over a wide range of parameters, compared to classical spectral analysis methods, and enables an unbiased comparison between spike trains recorded from different neurons and using different experimental protocols. PMID:25909328

  15. Quantifying spike train oscillations: biases, distortions and solutions.

    PubMed

    Matzner, Ayala; Bar-Gad, Izhar

    2015-04-01

    Estimation of the power spectrum is a common method for identifying oscillatory changes in neuronal activity. However, the stochastic nature of neuronal activity leads to severe biases in the estimation of these oscillations in single unit spike trains. Different biological and experimental factors cause the spike train to differentially reflect its underlying oscillatory rate function. We analyzed the effect of factors, such as the mean firing rate and the recording duration, on the detectability of oscillations and their significance, and tested these theoretical results on experimental data recorded in Parkinsonian non-human primates. The effect of these factors is dramatic, such that in some conditions, the detection of existing oscillations is impossible. Moreover, these biases impede the comparison of oscillations across brain regions, neuronal types, behavioral states and separate recordings with different underlying parameters, and lead inevitably to a gross misinterpretation of experimental results. We introduce a novel objective measure, the "modulation index", which overcomes these biases, and enables reliable detection of oscillations from spike trains and a direct estimation of the oscillation magnitude. The modulation index detects a high percentage of oscillations over a wide range of parameters, compared to classical spectral analysis methods, and enables an unbiased comparison between spike trains recorded from different neurons and using different experimental protocols. PMID:25909328

  16. LSND neutrino oscillation results

    SciTech Connect

    White, D.H.; LSND Collaboration

    1997-11-01

    The LSND experiment at Los Alamos has conducted a search for {anti v}{sub {mu}} {yields} {anti v}{sub e} oscillations using {anti v}{sub {mu}} from {mu}{sup +} decay at rest. The {anti v}{sub e} are detected via the reaction {anti v}{sub e} p {yields} e{sup +}n, correlated with the 2.2 MeV {gamma} from n p {yields} d {gamma}. The use of tight cuts to identify e{sup +} events with correlated {gamma} rays yielded 22 events with e{sup +} energy between 36 and 60 MeV and only 4.6 {+-} 0.6 background events. The probability that this excess is due entirely to a statistical fluctuation is 4.1 {times} 10{sup {minus}8}. A {chi}{sup 2} fit to the entire e{sup +} sample results in a total excess of 51.8{sub {minus}16.9}{sup +18.7} {+-} 8.0 events with e{sup +} energy between 20 and 60 MeV. If attributed to {anti v}{sub {mu}} {yields} {anti v}{sub e} oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of 0.31 {+-} 0.12 {+-} 0.05%.

  17. Laterally oscillating nitinol engine

    SciTech Connect

    Banks, R.

    1987-09-08

    This patent describes a laterally oscillating nitinol engine comprising: a first L-shaped drive member journalled for pivoting horizontal oscillation about the juncture of the legs of the L-shaped member, a second drive member journalled for pivoting about a point proximate the outboard end of the shorter leg of the L-shaped member at a distance from the pivot journal of the L-shaped member, a bearing block secured to the end of longer leg of the L-shaped and having a guide hole. The second member extending through the guide hole and arranged to reciprocate therein, a shape memory alloy power element disposed in flexure secured at its ends to the bearing block and to the second member intermediate the sliding connection with the bearing block and the pivotal connection of the second member, means for disposing different temperature baths below the element whereby as the drive members oscillate about their journals the element alternately dips into one bath and then the other, and means for absorbing a portion of the energy developed by the engine and moving the power element from the cold bath to the hot bath.

  18. LSND neutrino oscillation results

    SciTech Connect

    Louis, W.C.; LSND Collaboration

    1996-10-01

    The LSND (Liquid Scintillator Neutrino Detector) experiment at Los Alamos has conducted a search for muon antineutrino {r_arrow} electron antineutrino oscillations using muon neutrinos from antimuon decay at rest. The electron antineutrinos are detected via the reaction electron antineutrino + proton {r_arrow} positron + neutron, correlated with the 2.2-MeV gamma from neutron + proton {r_arrow} deuteron + gamma. The use of tight cuts to identify positron events with correlated gamma rays yields 22 events with positron energy between 36 and 60 MeV and only 4.6 {+-} 0.6 background events. The probability that this excess is due entirely to a statistical fluctuation is 4.1 {times} 10{sup -8}. A chi-squared fit to the entire positron sample results in a total excess of 51.8 {sup +18.7}{sub -16.9} {+-} 8.0 events with positron energy between 20 and 60 MeV. If attributed to muon antineutrino {r_arrow} electron antineutrino oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of (0.31 {+-} 0.12 {+-} 0.05){percent}. 10 refs., 7 figs., 1 tab.

  19. Temperature sensitive oscillator

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (Inventor)

    1986-01-01

    An oscillator circuit for sensing and indicating temperature by changing oscillator frequency with temperature comprises a programmable operational amplifier which is operated on the roll-off portion of its gain versus frequency curve and has its output directly connected to the inverting input to place the amplifier in a follower configuration. Its output is also connected to the non-inverting input by a capacitor with a crystal or other tuned circuit also being connected to the non-inverting input. A resistor is connected to the program input of the amplifier to produce a given set current at a given temperature, the set current varying with temperature. As the set current changes, the gain-bandwidth of the amplifier changes and, in turn, the reflected capacitance across the crystal changes, thereby providing the desired change in oscillator frequency by pulling the crystal. There is no requirement that a crystal employed with this circuit display either a linear frequency change with temperature or a substantial frequency change with temperature.

  20. Biochemical Oscillations and Cellular Rhythms

    NASA Astrophysics Data System (ADS)

    Goldbeter, Albert; Berridge, Foreword by M. J.

    1997-04-01

    1. Introduction; Part I. Glycolytic Oscillations: 2. Oscillatory enzymes: simple periodic behaviour in an allosteric model for glycolytic oscillations; Part II. From Simple to Complex Oscillatory Behaviour; 3. Birhythmicity: coexistence between two stable rhythms; 4. From simple periodic behaviour to complex oscillations, including bursting and chaos; Part III. Oscillations Of Cyclic Amo In Dictyostelium Cells: 5. Models for the periodic synthesis and relay of camp signals in Dictyostelium discoideum amoebae; 6. Complex oscillations and chaos in the camp signalling system of Dictyostelium; 7. The onset of camp oscillations in Dictyostelium as a model for the ontogenesis of biological rhythms; Part IV. Pulsatile Signalling In Intercellular Communication: 8. Function of the rhythm of intercellular communication in Dictyostelium. Link with pulsatile hormone secretion; Part V. Calcium Oscillations: 9. Oscillations and waves of intracellular calcium; Part VI. The Mitotic Oscillator: 10. Modelling the mitotic oscillator driving the cell division cycle; Part VII. Circadian Rhythms: 11. Towards a model for circadian oscillations in the Drosophila period protein (PER); 12. Conclusions and perspectives; References.

  1. Nonlinear Oscillators in Space Physics

    NASA Technical Reports Server (NTRS)

    Lester,Daniel; Thronson, Harley

    2011-01-01

    We discuss dynamical systems that produce an oscillation without an external time dependent source. Numerical results are presented for nonlinear oscillators in the Em1h's atmosphere, foremost the quasi-biennial oscillation (QBOl. These fluid dynamical oscillators, like the solar dynamo, have in common that one of the variables in a governing equation is strongly nonlinear and that the nonlinearity, to first order, has particular form. of 3rd or odd power. It is shown that this form of nonlinearity can produce the fundamental li'equency of the internal oscillation. which has a period that is favored by the dynamical condition of the fluid. The fundamental frequency maintains the oscillation, with no energy input to the system at that particular frequency. Nonlinearities of 2nd or even power could not maintain the oscillation.

  2. Multiple-site carcinogenicity of benzene in Fischer 344 rats and B6C3F1 mice.

    PubMed Central

    Huff, J E; Haseman, J K; DeMarini, D M; Eustis, S; Maronpot, R R; Peters, A C; Persing, R L; Chrisp, C E; Jacobs, A C

    1989-01-01

    Toxicology and carcinogenesis studies of benzene (CAS No. 71-43-2; greater than 99.7% pure) were conducted in groups of 60 F344/N rats and 60 B6C3F1 mice of each sex for each of three exposure doses and vehicle controls. These composite studies on benzene were designed and conducted because of large production volume and widespread human exposure, because of the epidemiologic association with leukemia, and because previous experiments were considered inadequate or inconclusive for determining carcinogenicity in laboratory animals. Using the results from 17-week studies, doses for the 2-year studies were selected based on clinical observations (tremors in higher dosed mice), on clinical pathologic findings (lymphoid depletion in rats and leukopenia in mice), and on body weight effects. Doses of 0, 50, 100, or 200 mg/kg body weight benzene in corn oil were administered by gavage to male rats, 5 days per week, for 103 weeks. Doses of 0, 25, 50, or 100 mg/kg benzene in corn oil were administered by gavage to female rats and to male and female mice for 103 weeks. Ten animals in each of the 16 groups were killed at 12 months, and necropsies were performed. Hematologic profiles were performed at 3-month intervals. For the 2-year studies, mean body weights of the top dose groups of male rats and of both sexes of mice were lower than those of the controls. Survivals of the top dose group of rats and mice of each sex were reduced; however, at week 92 for rats and week 91 for mice, survival was greater than 60% in all groups; most of the dosed animals that died before week 103 had neoplasia. Compound-related nonneoplastic or neoplastic effects on the hematopoietic system, Zymbal gland, forestomach, and adrenal gland were found both for rats and mice. Further, the oral cavity was affected in rats, and the lung, liver, Harderian gland, preputial gland, ovary, and mammary gland were affected in mice. Under the conditions of these 2-year gavage studies, there was clear evidence

  3. Genistein modulation of streptozotocin diabetes in male B6C3F1 mice can be induced by diet

    SciTech Connect

    Guo, Tai L.; Wang, Yunbiao; Xiong, Tao; Ling, Xiao; Zheng, Jianfeng

    2014-11-01

    Diet and phytoestrogens affect the development and progression of diabetes. The objective of the present study was to determine if oral exposure to phytoestrogen genistein (GE) by gavage changed blood glucose levels (BGL) through immunomodulation in streptozotocin (STZ)-induced diabetic male B6C3F1 mice fed with three different diets. These three diets were: NTP-2000 diet (NTP), soy- and alfalfa-free 5K96 diet (SOF) and high fat diet (HFD) with 60% of kcal from fat, primarily rendered fat of swine. The dosing regimen for STZ consisted of three 100 mg/kg doses (i.p.): the first dose was administered at approximately 2 weeks following the initiation of daily GE (20 mg/kg) gavage, and the second dose was on day 19 following the first dose, and the third dose was on day 57 following the first dose. In mice on the NTP diet, GE treatment decreased BGL with statistical significances observed on days 33 and 82 following the first STZ injection. In mice fed the HFD diet, GE treatment produced a significant decrease and a significant increase in BGL on days 15 and 89 following the first STZ injection, respectively. In mice fed the SOF diet, GE treatment had no significant effects on BGL. Although GE treatment affected phenotypic distributions of both splenocytes (T cells, B cells, natural killer cells and neutrophils) and thymocytes (CD4/CD8 and CD44/CD25), and their mitochondrial transmembrane potential and generation of reactive oxygen species, indicators of cell death (possibly apoptosis), GE modulation of neutrophils was more consistent with its diabetogenic or anti-diabetic potentials. The differential effects of GE on BGL in male B6C3F1 mice fed with three different diets with varied phytoestrogen contents suggest that the estrogenic properties of this compound may contribute to its modulation of diabetes. - Highlights: • Diets affected streptozotocin-induced diabetes in male B6C3F1 mice. • Genistein modulation of streptozotocin diabetes can be induced by diet.

  4. Discovery of new [1,4]dioxino[2,3-f]quinazoline-based inhibitors of EGFR including the T790M/L858R mutant.

    PubMed

    Qin, Xuemei; Li, Zhipeng; Yang, Leifu; Liu, Peng; Hu, Liming; Zeng, Chengchu; Pan, Zhiyong

    2016-07-01

    A novel series of 2,3-dihydro-[1,4]dioxino[2,3-f]quinazoline derivatives were designed, synthesized and evaluated as reversible and noncovalent epidermal growth factor receptor (EGFR) inhibitors. Most of the compounds exhibited good potency against EGFR(wt) and some showed moderate to excellent potency against EGFR(T790M/L858R) mutant. The half-maximal inhibitory concentration (IC50) values of twenty-one compounds against EGFR(wt) were less than 50nM, and those of six compounds were less than 10nM. The IC50 values of eleven compounds against EGFR(T790M/L858R) were less than 100nM. Among these, compound b1 displayed the most potent inhibitory activity against EGFR(wt) (IC50=2.0nM) and EGFR(T790M/L858R) (IC50=6.9nM). Compounds with excellent inhibitory activities against EGFR(wt) and EGFR(T790M/L858R) kinase inhibitory activities showed good antiproliferative activities against H358 and A549 cells. Docking study was performed to position compound b1 into the EGFR active pocket to determine the probable binding conformation. PMID:27234887

  5. Movements of HIV-1 genomic RNA-APOBEC3F complexes and PKR reveal cytoplasmic and nuclear PKR defenses and HIV-1 evasion strategies.

    PubMed

    Marin, Mariana; Golem, Sheetal; Kozak, Susan L; Kabat, David

    2016-02-01

    APOBEC3 cytidine deaminases and viral genomic RNA (gRNA) occur in virions, polysomes, and cytoplasmic granules, but have not been tracked together. Moreover, gRNA traffic is important, but the factors that move it into granules are unknown. Using in situ hybridization of transfected cells and protein synthesis inhibitors that drive mRNAs between locales, we observed APOBEC3F cotrafficking with gRNA without altering its movements. Whereas cells with little cytoplasmic gRNA were translationally active and accumulated Gag, suprathreshold amounts induced autophosphorylation of the cytoplasmic double-stranded RNA (dsRNA)-dependent protein kinase (PKR), causing eIF2α phosphorylation, protein synthesis suppression, and gRNA sequestration in stress granules. Additionally, we confirmed recent evidence that PKR is activated by chromosome-associated cellular dsRNAs after nuclear membranes disperse in prophase. By arresting cells in G2, HIV-1 blocks this mechanism for PKR activation and eIF2α phosphorylation. However, cytopathic membrane damage in CD4- and coreceptor-positive cultures infected with laboratory-adapted fusogenic HIV-1LAI eventually enabled PKR entry and activation in interphase nuclei. These results reveal multiple stages in the PKR-HIV-1 battleground that culminate in cell death. We discuss evidence suggesting that HIV-1s evolve in vivo to prevent or delay PKR activation by all these mechanisms. PMID:26626364

  6. Brain oscillations in bipolar disorder and lithium-induced changes

    PubMed Central

    Atagün, Murat İlhan

    2016-01-01

    Electroencephalography (EEG) studies in patients with bipolar disorder have revealed lower amplitudes in brain oscillations. The aim of this review is to describe lithium-induced EEG changes in bipolar disorder and to discuss potential underlying factors. A literature survey about lithium-induced EEG changes in bipolar disorder was performed. Lithium consistently enhances magnitudes of brain oscillations in slow frequencies (delta and theta) in both resting-state EEG studies as well as event-related oscillations studies. Enhancement of magnitudes of beta oscillations is specific to event-related oscillations. Correlation between serum lithium levels and brain oscillations has been reported. Lithium-induced changes in brain oscillations might correspond to lithium-induced alterations in neurotransmitters, signaling cascades, plasticity, brain structure, or biophysical properties of lithium. Therefore, lithium-induced changes in brain oscillations could be promising biomarkers to assess the molecular mechanisms leading to variability in efficacy. Since the variability of lithium response in bipolar disorder is due to the genetic differences in the mechanisms involving lithium, it would be highly promising to assess the lithium-induced EEG changes as biomarkers in genetic studies. PMID:27022264

  7. Detecting the H3F3A mutant allele found in high-grade pediatric glioma by real-time PCR.

    PubMed

    Zhang, Ray; Han, Jing; Daniels, David; Huang, Haojie; Zhang, Zhiguo

    2016-01-01

    Diffuse intrinsic pontine glioma (DIPG) is an aggressive pediatric brain tumor with a median survival of 1 year after diagnosis. It has been reported recently that about 80% of DIPG cases and 70% of midline glioblastomas contain a mutation at one allele of the H3F3A gene (encoding histone H3 variant H3.3), replacing the lysine 27 with methionine (K27M). In order to facilitate diagnosis of DIPG patients, a quick and reliable method to identify the H3F3A K27M mutation is needed. Here, we describe a real-time PCR-based procedure involving a mutant-specific primer, a blocker oligonucleotide, and a reverse primer that can differentiate samples with H3F3A K27M mutation from those that do not. We first tested four different mutant-specific primers for their ability to selectively amplify H3F3A K27M-mutant allele and found that one primer amplified the mutant allele more efficiently than the rest. We then determined the optimal concentration of blocker oligo that significantly improved amplification of the H3F3A K27M-mutant allele. Using this optimized real-time PCR assay, we analyzed eleven samples, two of which containing H3F3A K27M mutation, and found that these two samples were differentially amplified from the nine others. In addition, we were able to discern the H3F3A K27M mutation in a newly obtained pediatric brainstem glioblastoma sample whose H3.3 status was not known previously, and in three other DIPG samples as well as paraffin embedded samples. These results demonstrate that we have developed a new reliable procedure for detecting the H3F3A K27M mutation in pediatric glioblastoma patient samples. PMID:26376656

  8. Carbon nanotube oscillators toward zeptogram detection

    SciTech Connect

    Nishio, Mitsumasa; Sawaya, Shintaro; Akita, Seiji; Nakayama, Yoshikazu

    2005-03-28

    We demonstrate an application of a nanotube cantilever for zeptogram-level mass detection. This letter presents a quantitative method to measure the oscillation amplitude of a nanotube cantilever using a focused electron beam of a scanning electron microscope. The quality factor of {approx}1000 for the nanotube cantilever is revealed and the resolution of the resonant frequency is achieved to be {approx}10 Hz, which corresponds to a mass range of less than 100 zg at room temperature.

  9. Reattachment of Descemet's membrane using C3F8 gas in an eye with a Baerveldt aqueous shunt.

    PubMed

    Wimmersberger, Y; Bergin, C; Sharkawi, E

    2013-04-01

    Descemetʼs membrane detachment (DMD) is a rare complication following cataract and glaucoma surgery as well as lamellar graft procedures. DMD can lead to blurry vision, halos and severe visual loss. Clinically, when there is a large central detachment, a double anterior chamber is seen to form. In this scenario, surgical repair may be needed. Repair of localised DMD may be achieved by injection of gases such as perfluoropropane (C3F8) and sulfurhexafluoride (SF6) or sterile air. The effect of a functioning Baerveldt tube in situ during these injections has not been reported. We report a case of DMD repair in an eye with a Baerveldt aqueous shunt. PMID:23629780

  10. Coexistence of ferromagnetism and superconductivity in CeO_{0.3}F_{0.7}BiS_{2}

    SciTech Connect

    Lee, Jooseop; Demura, S; Stone, Matthew B; Iida, Kazuki; Ehlers, Georg; Dela Cruz, Clarina R; Matsuda, Masaaki; Deguchi, K; Mizuguchi, Y; Miura, O; Louca, Despina; Lee, Seung-Hun

    2014-01-01

    Bulk magnetization, transport and neutron scattering measurements were performed to investigate the electronic and magnetic properties of a polycrystalline sample of the newly discovered ferromagnetic superconductor, CeO0:3F0:7BiS2. Ferromagnetism develops below TFM = 6.54(8) K and superconductivity is found to coexist with the ferromagnetic state below TSC 4.5 K. Inelastic neutron scattering measurements reveal a very weakly dispersive magnetic excitation at 1.8 meV that can be explained by an Ising-like spin Hamiltonian. Under application of an external magnetic eld, the direction of the magnetic moment changes from the c-axis to the ab-plane and the 1.8 meV excitation splits into two modes. A possible mechanism for the unusual magnetism and its relation to superconductivity is discussed.

  11. Mechanism and nature of phase transitions in the (NH4)3MoO3F3 oxyfluoride

    NASA Astrophysics Data System (ADS)

    Flerov, I. N.; Fokina, V. D.; Bovina, A. F.; Bogdanov, E. V.; Molokeev, M. S.; Kocharova, A. G.; Pogorel'Tsev, E. I.; Laptash, N. M.

    2008-03-01

    The temperature dependences of the heat capacity, the unit cell parameter, and the permittivity for the (NH4)3MoO3F3 cryolite (space group Fm overline 3 m) are investigated. It is revealed that the compound undergoes ferroelectric and ferroelastic structural phase transitions at temperatures of 297 and 205 K, respectively. The mechanism of structural distortions is discussed in terms of the entropy parameters, pressure-temperature phase diagrams, and electron density maps for critical atoms. An analysis is made of the influence of the cation size and shape on the phase transitions in oxyfluorides of the general formula A 2 A' MO3 ( A,A' = NH4, K; M = Mo, W).

  12. Retinal Oscillations Carry Visual Information to Cortex

    PubMed Central

    Koepsell, Kilian; Wang, Xin; Vaingankar, Vishal; Wei, Yichun; Wang, Qingbo; Rathbun, Daniel L.; Usrey, W. Martin; Hirsch, Judith A.; Sommer, Friedrich T.

    2009-01-01

    Thalamic relay cells fire action potentials that transmit information from retina to cortex. The amount of information that spike trains encode is usually estimated from the precision of spike timing with respect to the stimulus. Sensory input, however, is only one factor that influences neural activity. For example, intrinsic dynamics, such as oscillations of networks of neurons, also modulate firing pattern. Here, we asked if retinal oscillations might help to convey information to neurons downstream. Specifically, we made whole-cell recordings from relay cells to reveal retinal inputs (EPSPs) and thalamic outputs (spikes) and then analyzed these events with information theory. Our results show that thalamic spike trains operate as two multiplexed channels. One channel, which occupies a low frequency band (<30 Hz), is encoded by average firing rate with respect to the stimulus and carries information about local changes in the visual field over time. The other operates in the gamma frequency band (40–80 Hz) and is encoded by spike timing relative to retinal oscillations. At times, the second channel conveyed even more information than the first. Because retinal oscillations involve extensive networks of ganglion cells, it is likely that the second channel transmits information about global features of the visual scene. PMID:19404487

  13. Synchronous Discrete Harmonic Oscillator

    SciTech Connect

    Antippa, Adel F.; Dubois, Daniel M.

    2008-10-17

    We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2{pi} in phase space, is an integral multiple N of the discrete time step {delta}t. It is fully synchronous when N is even. It is pseudo-synchronous when T/{delta}t is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is ''blue shifted'' relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval {delta}t. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.

  14. Carcinogenicity study of GSM and DCS wireless communication signals in B6C3F1 mice.

    PubMed

    Tillmann, Thomas; Ernst, Heinrich; Ebert, Sven; Kuster, Niels; Behnke, Wolfgang; Rittinghausen, Susanne; Dasenbrock, Clemens

    2007-04-01

    The purpose of this study using a total of 1170 B6C3F1 mice was to detect and evaluate possible carcinogenic effects in mice exposed to radio-frequency-radiation (RFR) from Global System for Mobile Communication (GSM) and Digital Personal Communications System (DCS) handsets as emitted by handsets operating in the center of the communication band, that is, at 902 MHz (GSM) and 1747 MHz (DCS). Restrained mice were exposed for 2 h per day, 5 days per week over a period of 2 years to three different whole-body averaged specific absorption rate (SAR) levels of 0.4, 1.3, 4.0 mW/g bw (SAR), or were sham exposed. Regarding the organ-related tumor incidence, pairwise Fisher's test did not show any significant increase in the incidence of any particular tumor type in the RF exposed groups as compared to the sham exposed group. Interestingly, while the incidences of hepatocellular carcinomas were similar in EMF and sham exposed groups, in both studies the incidences of liver adenomas in males decreased with increasing dose levels; the incidences in the high dose groups were statistically significantly different from those in the sham exposed groups. Comparison to published tumor rates in untreated mice revealed that the observed tumor rates were within the range of historical control data. In conclusion, the present study produced no evidence that the exposure of male and female B6C3F1 mice to wireless GSM and DCS radio frequency signals at a whole body absorption rate of up to 4.0 W/kg resulted in any adverse health effect or had any cumulative influence on the incidence or severity of neoplastic and non-neoplastic background lesions, and thus the study did not provide any evidence of RF possessing a carcinogenic potential. PMID:17019729

  15. Genistein modulation of streptozotocin diabetes in male B6C3F1 mice can be induced by diet

    PubMed Central

    Guo, Tai L.; Wang, Yunbiao; Xiong, Tao; Ling, Xiao; Zheng, Jianfeng

    2014-01-01

    Diet and phytoestrogens affect the development and progression of diabetes. The objective of the present study was to determine if oral exposure to phytoestrogen genistein (GE) by gavage changed blood glucose levels (BGL) through immunomodulation in streptozotocin (STZ)-induced diabetic male B6C3F1 mice fed three different diets. These three diets were: NTP-2000 diet (NTP), soy- and alfalfa-free 5K96 diet (SOF) and high fat diet (HFD) with 60% of kcal from fat, primarily rendered fat of swine. The dosing regimen for STZ consisted of three 100 mg/kg doses (i.p.): the first dose was administered at approximately 2 weeks following the initiation of daily GE (20 mg/kg) gavage, and the second dose was on day 19 following the first dose, and the third dose was on day 57 following the first dose. In mice on the NTP diet, GE treatment decreased BGL with statistical significances observed on days 33 and 82 following the first STZ injection. In mice fed the HFD diet, GE treatment produced a significant decrease and a significant increase in BGL on days 15 and 89 following the first STZ injection, respectively. In mice fed the SOF diet, GE treatment had no significant effects on BGL. Although GE treatment affected phenotypic distributions of both splenocytes (T cells, B cells, natural killer cells and neutrophils) and thymocytes (CD4/CD8 and CD44/CD25), and their mitochondrial transmembrane potential and generation of reactive oxygen species, indicators of cell death (possibly apoptosis), GE modulation of neutrophils was more consistent with its diabetogenic or anti-diabetic potentials. The differential effects of GE on BGL in male B6C3F1 mice fed three different diets with varied phytoestrogen contents suggest that the estrogenic properties of this compound may contribute to its modulation of diabetes. PMID:25178718

  16. Genotoxicity of malachite green and leucomalachite green in female Big Blue B6C3F1 mice.

    PubMed

    Mittelstaedt, Roberta A; Mei, Nan; Webb, Peggy J; Shaddock, Joseph G; Dobrovolsky, Vasily N; McGarrity, Lynda J; Morris, Suzanne M; Chen, Tao; Beland, Frederick A; Greenlees, Kevin J; Heflich, Robert H

    2004-07-11

    Malachite green, a triphenylmethane dye used in aquaculture as an antifungal agent, is rapidly reduced in vivo to leucomalachite green. Previous studies in which female B6C3F1 mice were fed malachite green produced relatively high levels of liver DNA adducts after 28 days, but no significant induction of liver tumors was detected in a 2-year feeding study. Comparable experiments conducted with leucomalachite green resulted in relatively low levels of liver DNA adducts but a dose-responsive induction of liver tumors. In the present study, we fed transgenic female Big Blue B6C3F1 mice with 450 ppm malachite green and 204 and 408 ppm leucomalachite green (the high doses used in the tumor bioassays) and evaluated genotoxicity after 4 and 16 weeks of treatment. Neither malachite green nor leucomalachite green increased the peripheral blood micronucleus frequency or Hprt lymphocyte mutant frequency at either time point; however, the 16-week treatment with 408 ppm leucomalachite green did increase the liver cII mutant frequency. Similar increases in liver cII mutant frequency were not seen in the mice treated for 16 weeks with malachite green or in female Big Blue rats treated with a comparable dose of leucomalachite green for 16 weeks in a previous study [Mutat. Res. 547 (2004) 5]. These results indicate that leucomalachite green is an in vivo mutagen in transgenic female mouse liver and that the mutagenicities of malachite green and leucomalachite green correlate with their tumorigenicities in mice and rats. The lack of increased micronucleus frequencies and lymphocyte Hprt mutants in female mice treated with leucomalachite green suggests that its genotoxicity is targeted to the tissue at risk for tumor induction. PMID:15238237

  17. Immunomodulatory effects of black cohosh (Actaea racemosa) extract in female B6C3F1/N mice

    PubMed Central

    Smith, Matthew J.; Germolec, Dori R.; Frawley, Rachel P.; White, Kimber L.

    2013-01-01

    Black cohosh extracts (BCE; Actaea racemosa) are being used worldwide as an alternative to hormone replacement therapy for the management of menstrual and menopausal symptoms, yet the effects of BCE on the immune system are largely unknown. Female B6C3F1/N mice were treated daily with BCE (0, 62.5, 125, 250, 500, or 1000 mg/kg) for 28 days by oral gavage. Liver weights were significantly increased (26%–32%) at the 1000 mg/kg dose. Dose-related increases in mean corpuscular volume and mean corpuscular hemoglobin were observed. Decreasing trends were observed in all thymic T cell populations, with the most notable dose-responsive effects on immature thymocytes. In the spleen, dose-related decreases were observed in all cell phenotypes evaluated, reaching the level of statistical significance at the 1000 mg/kg BCE dose. Splenic natural killer (NK) cell numbers were significantly decreased at all BCE doses, with the exception of absolute NK numbers at the 125 mg/kg dose. No effects were observed on T-dependent antibody responses of the humoral immune system, including the antibody-forming cell response to sheep erythrocytes (sRBC) and IgM antibody levels to both sRBC and keyhole limpet hemocyanin. Cytotoxic T cell (TCTL) activity was increased, as was the mixed leukocyte response in one of two studies. Anti-CD3 mediated proliferation and the delayed-type hypersensitivity response were unaffected. No effects were observed on innate immunity or on bone marrow cellularity and colony-forming units. Overall, BCE exposure in B6C3F1/N mice for 28 days at doses up to 1000 mg/kg had minimal immune effects, with the exception of an increased TCTL response. PMID:23571075

  18. Immunomodulatory effects of black cohosh (Actaea racemosa) extract in female B6C3F1/N mice.

    PubMed

    Smith, Matthew J; Germolec, Dori R; Frawley, Rachel P; White, Kimber L

    2013-06-01

    Black cohosh extracts (BCE; Actaea racemosa) are being used worldwide as an alternative to hormone replacement therapy for the management of menstrual and menopausal symptoms, yet the effects of BCE on the immune system are largely unknown. Female B6C3F1/N mice were treated daily with BCE (0, 62.5, 125, 250, 500, or 1000mg/kg) for 28 days by oral gavage. Liver weights were significantly increased (26-32%) at the 1000mg/kg dose. Dose-related increases in mean corpuscular volume and mean corpuscular hemoglobin were observed. Decreasing trends were observed in all thymic T cell populations, with the most notable dose-responsive effects on immature thymocytes. In the spleen, dose-related decreases were observed in all cell phenotypes evaluated, reaching the level of statistical significance at the 1000mg/kg BCE dose. Splenic natural killer (NK) cell numbers were significantly decreased at all BCE doses, with the exception of absolute NK numbers at the 125mg/kg dose. No effects were observed on T-dependent antibody responses of the humoral immune system, including the antibody-forming cell response to sheep erythrocytes (sRBC) and IgM antibody levels to both sRBC and keyhole limpet hemocyanin. Cytotoxic T cell (TCTL) activity was increased, as was the mixed leukocyte response in one of two studies. Anti-CD3 mediated proliferation and the delayed-type hypersensitivity response were unaffected. No effects were observed on innate immunity or on bone marrow cellularity and colony-forming units. Overall, BCE exposure in B6C3F1/N mice for 28 days at doses up to 1000mg/kg had minimal immune effects, with the exception of an increased TCTL response. PMID:23571075

  19. Genistein modulation of streptozotocin diabetes in male B6C3F1 mice can be induced by diet.

    PubMed

    Guo, Tai L; Wang, Yunbiao; Xiong, Tao; Ling, Xiao; Zheng, Jianfeng

    2014-11-01

    Diet and phytoestrogens affect the development and progression of diabetes. The objective of the present study was to determine if oral exposure to phytoestrogen genistein (GE) by gavage changed blood glucose levels (BGL) through immunomodulation in streptozotocin (STZ)-induced diabetic male B6C3F1 mice fed with three different diets. These three diets were: NTP-2000 diet (NTP), soy- and alfalfa-free 5K96 diet (SOF) and high fat diet (HFD) with 60% of kcal from fat, primarily rendered fat of swine. The dosing regimen for STZ consisted of three 100mg/kg doses (i.p.): the first dose was administered at approximately 2weeks following the initiation of daily GE (20mg/kg) gavage, and the second dose was on day 19 following the first dose, and the third dose was on day 57 following the first dose. In mice on the NTP diet, GE treatment decreased BGL with statistical significances observed on days 33 and 82 following the first STZ injection. In mice fed the HFD diet, GE treatment produced a significant decrease and a significant increase in BGL on days 15 and 89 following the first STZ injection, respectively. In mice fed the SOF diet, GE treatment had no significant effects on BGL. Although GE treatment affected phenotypic distributions of both splenocytes (T cells, B cells, natural killer cells and neutrophils) and thymocytes (CD4/CD8 and CD44/CD25), and their mitochondrial transmembrane potential and generation of reactive oxygen species, indicators of cell death (possibly apoptosis), GE modulation of neutrophils was more consistent with its diabetogenic or anti-diabetic potentials. The differential effects of GE on BGL in male B6C3F1 mice fed with three different diets with varied phytoestrogen contents suggest that the estrogenic properties of this compound may contribute to its modulation of diabetes. PMID:25178718

  20. THz Local Oscillator Sources

    NASA Astrophysics Data System (ADS)

    Mehdi, Imran; Schlecht, Erich; Chattopadhyay, Goutam; Siegel, Peter H.

    Most operational Submillimeter-wave radio telescopes, both space borne and ground based, employ local oscillator sources based on Gunn diodes followed by whisker contacted Schottky multipliers. Enough progress, however, has been made on a number of fronts to conclude that next generation of radio telescopes that become operational in the new Millennium will have a different local oscillator (LO) generation architecture. MMIC power amplifiers with impressive gain in the Ka- to-W band have enabled the use of microwave synthesizers which can then be actively multiplied to provide a frequency agile power source beyond 100 GHz. This medium power millimeter source can then be amplified to enable efficient pumping of follow-on balanced multiplier stages. Input power to the multipliers can be further enhanced by power combining to achieve close to half a Watt at W-band. An 800 GHz three-stage multiplier chain, implemented this way has demonstrated a peak output power of 1 mW. A second advance in LO generation lies in the Schottky diode varactor technology. Planar Schottky diode multipliers have now been demonstrated up to 1500 GHz and it can be assumed that most of the future multiplier chains will be based on these robust devices rather than the whisker contacted diode of the past. The ability to produce planar GaAs diode chips deep into the THz range, with submicron dimensions, has opened up a wide range of circuit design space which can be taken advantage of to improve efficiency, bandwidth, and power handling capability of the multipliers. A third breakthrough has been the demonstration of photonic based LO sources utilizing GaAs photomixers. These sources, though not yet implemented in robust space borne missions, offer a number of advantages over their electronic counterparts, including extremely broad tuning, fiber coupled components, and solid-state implementation. Another development, which holds some promise, is the use of micro-machining technology to implement

  1. CORE SATURATION BLOCKING OSCILLATOR

    DOEpatents

    Spinrad, R.J.

    1961-10-17

    A blocking oscillator which relies on core saturation regulation to control the output pulse width is described. In this arrangement an external magnetic loop is provided in which a saturable portion forms the core of a feedback transformer used with the thermionic or semi-conductor active element. A first stationary magnetic loop establishes a level of flux through the saturation portion of the loop. A second adjustable magnet moves the flux level to select a saturation point giving the desired output pulse width. (AEC)

  2. Second harmonic FEL oscillation

    NASA Astrophysics Data System (ADS)

    Neil, George R.; Benson, S. V.; Biallas, G.; Freund, H. P.; Gubeli, J.; Jordan, K.; Myers, S.; Shinn, M. D.

    2002-05-01

    We have produced and measured for the first time second harmonic oscillation in the infrared region by the high-average-power Jefferson Lab Infrared Free Electron Laser. The finite geometry and beam emittance allows sufficient gain for lasing to occur. We were able to lase at pulse rates up to 74.85 MHz and could produce over 4.5 W average and 40 kW peak of IR power in a 40 nm FWHM bandwidth at 2925 nm. In agreement with predictions, the source preferentially lased in a TEM 01 mode. We present results of initial source performance measurements and comparisons with theory and simulation.

  3. Second Harmonic FEL Oscillation

    NASA Astrophysics Data System (ADS)

    Neil, George R.; Benson, S. V.; Biallas, G.; Gubeli, J.; Jordan, K.; Myers, S.; Shinn, M. D.

    2001-08-01

    We have produced and measured for the first time second harmonic oscillation in the infrared region by a free electron laser. Although such lasing is ideally forbidden, since the gain of a plane wave is zero on axis for an electron beam perfectly aligned with a wiggler, a transverse mode antisymmetry allows sufficient gain in this experiment for lasing to occur. We lased at pulse rates up to 74.85 MHz and could produce over 4.5 W average and 40 kW peak of IR power in a 40 nm FWHM bandwidth at 2925 nm. In agreement with predictions, the source preferentially lased in a TEM01 mode.

  4. Predicting the closed-loop stability and oscillation amplitude of nonlinear parametrically amplified oscillators

    NASA Astrophysics Data System (ADS)

    Zega, V.; Nitzan, S.; Li, M.; Ahn, C. H.; Ng, E.; Hong, V.; Yang, Y.; Kenny, T.; Corigliano, A.; Horsley, D. A.

    2015-06-01

    This work investigates the closed-loop operation of microelectromechanical oscillators in the presence of both cubic (Duffing) nonlinearities and parametric amplification. We present a theoretical model for this system that enables us to predict oscillation amplitude and instability and experimentally verify it using a silicon disk resonator with a quality factor (Q) of 85 000 and a natural frequency of 251 kHz. We determine that, contrary to previous understanding gained from analyzing the open-loop system, the presence of cubic nonlinearities does not limit the maximum stable oscillation amplitude if the resonator is operated in a closed loop. In addition, the stability and amplitude behavior predicted by our theoretical model are independent of the presence or severity of cubic nonlinearities, or on drive amplitude.

  5. Brain Oscillations, Hypnosis, and Hypnotizability

    PubMed Central

    Jensen, Mark P.; Adachi, Tomonori; Hakimian, Shahin

    2014-01-01

    In this article, we summarize the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, and are usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. Here we propose that it is this role that may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis; specifically that theta oscillations may facilitate, and that changes in gamma activity observed with hypnosis may underlie, some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis, and for enhancing response to hypnotic treatments. PMID:25792761

  6. Stable And Oscillating Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  7. Saltpotentin Version3.f

    Energy Science and Technology Software Center (ESTSC)

    2008-06-25

    The program inverts gravity and/or gravity gradient, and/or magnetic field (magnitude, in direction of Earth's magnetic field), at a number of points, for the position of bottom of a layer, in a structure with one or multiple layers of a uniform material (e.g., salt) in a host of known (and possibly varying) background density an/or susceptibility, is specified over a 3-D collection of rectangular blocks. For marine applications, water density (and/or susceptibility) and bathmetry ismore » also specified. The interface found is the smoothest found for its level of data misfit, with the desired level of data misfie set as an input parameter. The densities and susceptibilites used for a block depend on its position relative to the interfaces. The first interface give the sea floor position. Blocks above the sea floor are treated as having the wate density and susceptibility given by the background density and susceptibility specified over the 3-D grid of blocks. For 1 even, blocks between the 1'th and 1+1'h interfaces are treated as having a uniform density and susceptibility specified as an input parameter.« less

  8. Policy oscillation is overshooting.

    PubMed

    Wagner, Paul

    2014-04-01

    A majority of approximate dynamic programming approaches to the reinforcement learning problem can be categorized into greedy value function methods and value-based policy gradient methods. The former approach, although fast, is well known to be susceptible to the policy oscillation phenomenon. We take a fresh view to this phenomenon by casting, within the context of non-optimistic policy iteration, a considerable subset of the former approach as a limiting special case of the latter. We explain the phenomenon in terms of this view and illustrate the underlying mechanism with artificial examples. We also use it to derive the constrained natural actor-critic algorithm that can interpolate between the aforementioned approaches. In addition, it has been suggested in the literature that the oscillation phenomenon might be subtly connected to the grossly suboptimal performance in the Tetris benchmark problem of all attempted approximate dynamic programming methods. Based on empirical findings, we offer a hypothesis that might explain the inferior performance levels and the associated policy degradation phenomenon, and which would partially support the suggested connection. Finally, we report scores in the Tetris problem that improve on existing dynamic programming based results by an order of magnitude. PMID:24491826

  9. Neutrino Oscillations:. Hierarchy Question

    NASA Astrophysics Data System (ADS)

    Ernst, D. J.; Cogswell, B. K.; Burroughs, H. R.; Escamilla-Roa, J.; Latimer, D. L.

    2014-09-01

    The only experimentally observed phenomenon that lies outside the standard model of the electroweak interaction is neutrino oscillations. A way to try to unify the extensive neutrino oscillation data is to add a phenomenological mass term to the Lagrangian that is not diagonal in the flavor basis. The goal is then to understand the world's data in terms of the parameters of the mixing matrix and the differences between the squares of the masses of the neutrinos. An outstanding question is what is the correct ordering of the masses, the hierarchy question. We point out a broken symmetry relevant to this question, the symmetry of the simultaneous interchange of hierarchy and the sign of θ13. We first present the results of an analysis of data that well determine the phenomenological parameters but are not sensitive to the hierarchy. We find θ13 = 0.152±0.014, θ 23 = 0.25{ - 0.05}{ + 0.03} π and Δ32 = 2.45±0.14×10-3 eV2, results consistent with others. We then include data that are sensitive to the hierarchy and the sign of θ13. We find, unlike others, four isolated minimum in the χ2-space as predicted by the symmetry. Now that Daya Bay and RENO have determined θ13 to be surprisingly large, the Super-K atmospheric data produce meaningful symmetry breaking such that the inverse hierarchy is preferred at the 97.2 % level.

  10. Neutrino oscillations refitted

    NASA Astrophysics Data System (ADS)

    Forero, D. V.; Tórtola, M.; Valle, J. W. F.

    2014-11-01

    Here, we update our previous global fit of neutrino oscillations by including the recent results that have appeared since the Neutrino 2012 conference. These include the measurements of reactor antineutrino disappearance reported by Daya Bay and RENO, together with latest T2K and MINOS data including both disappearance and appearance channels. We also include the revised results from the third solar phase of Super-Kamiokande, SK-III, as well as new solar results from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred global determination of the atmospheric angle θ23 is consistent with maximal mixing. We also determine the impact of the new data upon all the other neutrino oscillation parameters with an emphasis on the increasing sensitivity to the C P phase, thanks to the interplay between accelerator and reactor data. In the Appendix, we present the updated results obtained after the inclusion of new reactor data presented at the Neutrino 2014 conference. We discuss their impact on the global neutrino analysis.

  11. Chemotaxis and Actin Oscillations

    NASA Astrophysics Data System (ADS)

    Bodenschatz, Eberhard; Hsu, Hsin-Fang; Negrete, Jose; Beta, Carsten; Pumir, Alain; Gholami, Azam; Tarantola, Marco; Westendorf, Christian; Zykov, Vladimir

    Recently, self-oscillations of the cytoskeletal actin have been observed in Dictyostelium, a model system for studying chemotaxis. Here we report experimental results on the self-oscillation mechanism and the role of regulatory proteins and myosin II. We stimulate cells rapidly and periodically by using photo un-caging of the chemoattractant in a micro-fluidic device and measured the cellular responses. We found that the response amplitude grows with stimulation strength only in a very narrow region of stimulation, after which the response amplitude reaches a plateau. Moreover, the frequency-response is not constant but rather varies with the strength of external stimuli. To understand the underlying mechanism, we analyzed the polymerization and de-polymerization time in the single cell level. Despite of the large cell-to-cell variability, we found that the polymerization time is independent of external stimuli and the de-polymerization time is prolonged as the stimulation strength increases. Our conclusions will be summarized and the role of noise in the signaling network will be discussed. German Science Foundation CRC 937.

  12. Socially synchronized circadian oscillators

    PubMed Central

    Bloch, Guy; Herzog, Erik D.; Levine, Joel D.; Schwartz, William J.

    2013-01-01

    Daily rhythms of physiology and behaviour are governed by an endogenous timekeeping mechanism (a circadian ‘clock’). The alternation of environmental light and darkness synchronizes (entrains) these rhythms to the natural day–night cycle, and underlying mechanisms have been investigated using singly housed animals in the laboratory. But, most species ordinarily would not live out their lives in such seclusion; in their natural habitats, they interact with other individuals, and some live in colonies with highly developed social structures requiring temporal synchronization. Social cues may thus be critical to the adaptive function of the circadian system, but elucidating their role and the responsible mechanisms has proven elusive. Here, we highlight three model systems that are now being applied to understanding the biology of socially synchronized circadian oscillators: the fruitfly, with its powerful array of molecular genetic tools; the honeybee, with its complex natural society and clear division of labour; and, at a different level of biological organization, the rodent suprachiasmatic nucleus, site of the brain's circadian clock, with its network of mutually coupled single-cell oscillators. Analyses at the ‘group’ level of circadian organization will likely generate a more complex, but ultimately more comprehensive, view of clocks and rhythms and their contribution to fitness in nature. PMID:23825203

  13. Starting current of coaxial relative backward wave oscillator

    SciTech Connect

    Teng Yan; Xiao Renzhen; Liu Guozhi; Chen Changhua; Shao Hao; Tang Chuanxiang

    2010-06-15

    This paper is devoted to study the starting current of the coaxial relativistic backward wave oscillator (CRBWO) using a simple physical model that employs the eigenmodes of the enclosed resonant cavity and the external quality factor of the open cavity Q. The agreement between the theoretical and simulation results is presented. It is found that CRBWO is suffering from the mode competition during the startup of the oscillation due to the wide interaction region over the range of the longitudinal wavenumbers.

  14. Theories of white dwarf oscillations

    NASA Technical Reports Server (NTRS)

    Vanhorn, H. M.

    1980-01-01

    The current status of theoretical understanding of the oscillations observed in the ZZ Ceti stars and cataclysmic variables is briefly reviewed. Nonradial g-mode oscillations appear to provide a satisfactory explanation for the low amplitude variables such as R548, with periods in the range of approximately 200 to 300 seconds, but for the longer period (800 to 1000 seconds) oscillators, the situation is still unclear. Rotation may play an important role in this problem, and the effects of both slow and fast rotation upon the mode structure are discussed. In the cataclysmic variables, both accretion and thermonuclear burning may act to excite oscillations of the white dwarf.

  15. Modelling Ultradian Oscillations and Segmentation

    NASA Astrophysics Data System (ADS)

    Jensen, Mogens

    2008-03-01

    We model ultradian oscillations in four different eucaryotic systems: Hes1, p53-mdm2, NF-kB and Wnt-Notch. In each of the systems we identify the feed-back loops for the genetic regulations. Oscillations are possible when time delays are present, either by directly introducing a delay, by many steps in the loops or by saturated degradation. The oscillations are important for apoptosis and control of inflammation. The Wnt-Notch system is essential in embryo segmentation and we introduce a model in which the Wnt oscillates by itself but drives the Notch cycle out of phase with the Wnt cycle, in good agreement with experimental observations.

  16. Quartz-crystal-oscillator hygrometer

    NASA Technical Reports Server (NTRS)

    Kruger, R.

    1977-01-01

    Measuring device, which eliminates complex and expensive optical components by electronically sensing dewpoint of water vapor in gas, employs piezoelectric crystal oscillator, supportive circuitry, temperature regulators, and readout.

  17. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J. (Inventor); Blosser, Max L. (Inventor); Camarda, Charles J. (Inventor)

    1992-01-01

    Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators, or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.

  18. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J. (Inventor); Blosser, Max L. (Inventor); Camarda, Charles J. (Inventor)

    1993-01-01

    Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.

  19. Symmetries of coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.

    1993-01-01

    It is shown that the system of two coupled harmonic oscillators possesses many interesting symmetries. It is noted that the symmetry of a single oscillator is that of the three-parameter group Sp(2). Thus two uncoupled oscillator exhibits a direct product of two Sp(2) groups, with six parameters. The coupling can be achieved through a rotation in the two-dimensional space of two oscillator coordinates. The closure of the commutation relations for the generators leads to the ten-parameter group Sp(4) which is locally isomorphic to the deSitter group O(3,2).

  20. A study of neutrino oscillations in MINOS

    SciTech Connect

    Raufer, Tobias Martin; /Oxford U.

    2007-06-01

    MINOS is a long-baseline neutrino oscillations experiment located at Fermi National Accelerator Laboratory (FNAL), USA. It makes use of the NuMI neutrino beamline and two functionally identical detectors located at distances of {approx}1km and {approx}735km from the neutrino production target respectively. The Near Detector measures the composition and energy spectrum of the neutrino beam with high precision while the Far Detector looks for evidence of neutrino oscillations. This thesis presents work conducted in two distinct areas of the MINOS experiment: analysis of neutral current and charged current interactions. While charged current events are only sensitive to muon neutrino disappearance, neutral current events can be used to distinguish oscillations into sterile neutrinos from those involving only active neutrino species. A complete, preliminary neutral current study is performed on simulated data. This is followed by a more detailed investigation of neutral current neutrino interactions in the MINOS Near Detector. A procedure identifying neutral current interactions and rejecting backgrounds due to reconstruction failures is developed. Two distinct event classification methods are investigated. The selected neutral current events in the Near Detector are used to extract corrections to the neutral current cross-section in the MINOS Monte Carlo simulation as a function of energy. The resulting correction factors are consistent with unity. The main MINOS charged current neutrino disappearance analysis is described. We present the Monte Carlo tuning procedure, event selection, extrapolation from Near to Far Detector and fit for neutrino oscillations. Systematic errors on this measurement are evaluated and discussed in detail. The data are consistent with neutrino oscillations with the following parameters: 2.74 {sup +0.44}{sub -0.26} x 10{sup -3} eV{sup 2} and sin{sup 2}(2{theta}{sub 23}) > 0.87 at 68% confidence level.

  1. Structural, electronic and optical properties of novel carbonate fluorides ABCO{sub 3}F (A=K, Rb, Cs; B=Ca, Sr)

    SciTech Connect

    Narsimha Rao, E.; Appalakondaiah, S.; Yedukondalu, N.; Vaitheeswaran, G.

    2014-04-01

    In the present study, we performed first principles calculations on the electronic and optical properties of layered alkali–alkaline earth carbonate fluorides which attract attention in the domain of nonlinear optics. The calculated lattice parameters and volumes with and without inclusion of van der Waals (vdW) correction methods to standard density functional methods were compared with experiments. We observed that vdW interactions are predominant in RbCaCO{sub 3}F and CsCaCO{sub 3}F as compared with other computed compounds. The calculated bulk modulus from single crystal elastic constants reveals that these materials are all relatively harder than the KH{sub 2}PO{sub 4} (KDP) crystal. We also found that these materials are wide band gap insulators as obtained from Tran–Blaha modified Becke–Johnson potential. The linear optical properties such as dielectric function, refractive indices, birefringence and absorption spectra are presented. Finally, the calculated birefringence values indicate that these crystals could be promising for producing phase matching in the deep ultra-violet region. - Graphical abstract: The co- and anti-parallel alignment of CO{sub 3} groups leads to larger and smaller SHG coefficients in (a) KCaCO{sub 3}F, (b) KSrCO{sub 3}F, (c) RbSrCO{sub 3}F, (d) RbCaCO{sub 3}F, and (e) CsCaCO{sub 3}F. - Highlights: • Effect of van der Waals interactions on structural properties. • Single-crystalline elastic constants and mechanical stability. • Electronic properties. • Linear optical properties. • Comparison of present computed compounds with other well known materials in non-linear optical materials.

  2. Stable local oscillator microcircuit.

    SciTech Connect

    Brocato, Robert Wesley

    2006-10-01

    This report gives a description of the development of a Stable Local Oscillator (StaLO) Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. The StaLO uses a comb generator followed by surface acoustic wave (SAW) filters. The comb generator creates a set of harmonic components of the 100MHz input signal. The SAW filters are narrow bandpass filters that are used to select the desired component and reject all others. The resulting circuit has very low sideband power levels and low phase noise (both less than -40dBc) that is limited primarily by the phase noise level of the input signal.

  3. Multifrequency optoelectronic oscillator

    NASA Astrophysics Data System (ADS)

    Jiang, Yang; Liang, Jianhui; Bai, Guangfu; Hu, Lin; Cai, Shaohong; Li, Hongxia; Shan, Yuanyuan; Ma, Chuang

    2014-11-01

    We propose a simple and cost-effective multifrequency optoelectronic oscillator (OEO) which is able to simultaneously generate two or more independent microwave signals by adding parallel filtering branches in the feedback loop. In the experimental demonstration, two signals with frequencies of 20 and 9 GHz are successfully generated. Compared with a conventional OEO, the generated signals have no additional noise and do not interfere with each other. The side-mode suppression by the optical dual-loop configuration is effective for both channels. The measured side-mode suppression ratios are larger than 65 dB, and the phase noises at a 10-kHz frequency offset are -108 and -113 dBc/Hz for 20 and 9-GHz signals, respectively.

  4. Galilean covariant harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Horzela, Andrzej; Kapuscik, Edward

    1993-01-01

    A Galilean covariant approach to classical mechanics of a single particle is described. Within the proposed formalism, all non-covariant force laws defining acting forces which become to be defined covariantly by some differential equations are rejected. Such an approach leads out of the standard classical mechanics and gives an example of non-Newtonian mechanics. It is shown that the exactly solvable linear system of differential equations defining forces contains the Galilean covariant description of harmonic oscillator as its particular case. Additionally, it is demonstrated that in Galilean covariant classical mechanics the validity of the second Newton law of dynamics implies the Hooke law and vice versa. It is shown that the kinetic and total energies transform differently with respect to the Galilean transformations.

  5. Toxicity and carcinogenicity studies of Caramel Colour IV in F344 rats and B6C3F1 mice.

    PubMed

    MacKenzie, K M; Boysen, B G; Field, W E; Petsel, S R; Chappel, C I; Emerson, J L; Stanley, J

    1992-05-01

    Caramel Colour IV, a type of caramel colour used in the manufacture of cola soft drinks, was evaluated for subchronic and chronic toxicity in rats, and carcinogenicity in Fischer-344 (F344) rats and B6C3F1 mice. In each of the studies, Caramel Colour IV was mixed with demineralized water and the solutions given to the animals ad lib. in the drinking fluid. The concentrations of Caramel Colour IV in the drinking fluid were adjusted periodically to achieve the desired caramel colour intake per kg body weight. In the range-finding studies, groups of 30 rats/sex were given Caramel Colour IV at levels of 0, 15, 20, 25 or 30 g/kg for 13 wk, and groups of 10 male rats were given levels of 0, 2.5, 5, 10 or 15 g/kg for 6 wk followed, for some dose groups, by a 2-wk withdrawal period, and then re-initiation of dosing for another 2 wk. In the rat chronic toxicity study, levels of Caramel Colour IV of 0, 2.5, 5, 7.5 or 10 g/kg were given to groups of 25 rats/sex for 12 months. The test groups in the rat and mouse carcinogenicity studies were composed of 50 animals/sex and each species was given the caramel colour at levels of 0, 0, 2.5, 5 or 10 g/kg for 24 months. In each of the studies, treated animals tended to have dose-related lower water consumption than controls. This was attributed to poor palatability of the drinking fluid, and was generally associated with decreased food consumption and body weights. Rats given caramel colour often had soft or liquid malodorous faeces although there were no treatment-related ante-mortem observations in mice. Blood biochemical changes in the rat (i.e. reduced blood urea nitrogen, alkaline phosphatase and total serum protein) appeared to be related to dietary influences and were not considered toxicologically significant. There were no treatment-related alterations in haematological variables or treatment-related differences in survival or in the incidence of benign or malignant tumours among treated and control groups and no

  6. Structure-property correlation over five phases and four transitions in Pb5Al3F19.

    PubMed

    Abrahams, S C; Ravez, J; Ritter, H; Ihringer, J

    2003-10-01

    The calorimetric and dielectric properties of Pb(5)Al(3)F(19) in the five phases stable under ambient pressure are correlated with structure for fuller characterization of each phase. The first-order transition between ferroelectric phase V and antiferroelectric phase IV at T(V,IV) = 260 (5) K exhibits a thermal hysteresis of 135 (5) K on heating, with a maximum atomic displacement Delta(xyz)(max) = 1.21 (6) A; the transition from phase IV to ferroelastic phase III at 315 (5) K is also first order but with a thermal hysteresis of 10 (5) K and Delta(xyz)(max) = 0.92 (7) A; that from phase III to paraelastic phase II at 360 (5) K is second order without hysteresis and has Delta(xyz)(max) = 0.69 (4) A; and the transition from phase II to paraelectric phase I at 670 (5) K is second or higher order, with Delta(xyz)(max) = 0.7 (4) A. The measured entropy change DeltaS at T(V,IV) agrees well with DeltaS as derived from the increased configurational energy by Stirling's approximation. For all other phase transitions, 0.5 > or = DeltaS > 0 J mol(-1) K(-1) is consistent with an entropy change caused primarily by the changes in the vibrational energy. The structure of phase III is determined both by group theoretical/normal mode analysis and by consideration of the structures of phases II, IV and V reported previously; refinement is by simultaneous Rietveld analysis of the X-ray and neutron diffraction powder profiles. The structure of prototypic phase I is predicted on the basis of the atomic arrangement in phases II, III, IV and V. The introduction of 3d electrons into the Pb(5)Al(3)F(19) lattice disturbs the structural equilibrium, the addition of 0.04% Cr(3+) causing significant changes in atomic positions and increasing T(IV,III) by approximately 15 K. Substitution of Al(3+) by 20% or more Cr(3+) eliminates the potential minima that otherwise stabilize phases IV, III and II. PMID:14586075

  7. Probing deformed commutators with macroscopic harmonic oscillators

    PubMed Central

    Bawaj, Mateusz; Biancofiore, Ciro; Bonaldi, Michele; Bonfigli, Federica; Borrielli, Antonio; Di Giuseppe, Giovanni; Marconi, Lorenzo; Marino, Francesco; Natali, Riccardo; Pontin, Antonio; Prodi, Giovanni A.; Serra, Enrico; Vitali, David; Marin, Francesco

    2015-01-01

    A minimal observable length is a common feature of theories that aim to merge quantum physics and gravity. Quantum mechanically, this concept is associated with a nonzero minimal uncertainty in position measurements, which is encoded in deformed commutation relations. In spite of increasing theoretical interest, the subject suffers from the complete lack of dedicated experiments and bounds to the deformation parameters have just been extrapolated from indirect measurements. As recently proposed, low-energy mechanical oscillators could allow to reveal the effect of a modified commutator. Here we analyze the free evolution of high-quality factor micro- and nano-oscillators, spanning a wide range of masses around the Planck mass mP (≈22 μg). The direct check against a model of deformed dynamics substantially lowers the previous limits on the parameters quantifying the commutator deformation. PMID:26088965

  8. Parametric phase diffusion analysis of irregular oscillations

    NASA Astrophysics Data System (ADS)

    Schwabedal, Justus T. C.

    2014-09-01

    Parametric phase diffusion analysis (ΦDA), a method to determine variability of irregular oscillations, is presented. ΦDA is formulated as an analysis technique for sequences of Poincaré return times found in numerous applications. The method is unbiased by the arbitrary choice of Poincaré section, i.e. isophase, which causes a spurious component in the Poincaré return times. Other return-time variability measures can be biased drastically by these spurious return times, as shown for the Fano factor of chaotic oscillations in the Rössler system. The empirical use of ΦDA is demonstrated in an application to heart rate data from the Fantasia Database, for which ΦDA parameters successfully classify heart rate variability into groups of age and gender.

  9. Probing deformed commutators with macroscopic harmonic oscillators.

    PubMed

    Bawaj, Mateusz; Biancofiore, Ciro; Bonaldi, Michele; Bonfigli, Federica; Borrielli, Antonio; Di Giuseppe, Giovanni; Marconi, Lorenzo; Marino, Francesco; Natali, Riccardo; Pontin, Antonio; Prodi, Giovanni A; Serra, Enrico; Vitali, David; Marin, Francesco

    2015-01-01

    A minimal observable length is a common feature of theories that aim to merge quantum physics and gravity. Quantum mechanically, this concept is associated with a nonzero minimal uncertainty in position measurements, which is encoded in deformed commutation relations. In spite of increasing theoretical interest, the subject suffers from the complete lack of dedicated experiments and bounds to the deformation parameters have just been extrapolated from indirect measurements. As recently proposed, low-energy mechanical oscillators could allow to reveal the effect of a modified commutator. Here we analyze the free evolution of high-quality factor micro- and nano-oscillators, spanning a wide range of masses around the Planck mass mP (≈ 22 μg). The direct check against a model of deformed dynamics substantially lowers the previous limits on the parameters quantifying the commutator deformation. PMID:26088965

  10. Joint entropy of quantum damped harmonic oscillators

    NASA Astrophysics Data System (ADS)

    Aguiar, V.; Guedes, I.

    2014-05-01

    We use the dynamical invariant method and a unitary transformation to obtain the exact Schrödinger wave function, ψn(x,t), and calculate for n=0 the time-dependent joint entropy (Leipnik’s entropy) for two classes of quantum damped harmonic oscillators. We observe that the joint entropy does not vary in time for the Caldirola-Kanai oscillator, while it decreases and tends to a constant value (ln({e}/{2})) for asymptotic times for the Lane-Emden ones. This is due to the fact that for the latter, the damping factor decreases as time increases. The results show that the time dependence of the joint entropy is quite complex and does not obey a general trend of monotonously increase with time.

  11. Observationally determined Fe II oscillator strengths

    NASA Astrophysics Data System (ADS)

    Shull, J. M.; van Steenberg, M.; Seab, C. G.

    1983-08-01

    Absorption oscillator strengths for 21 Fe II resonance lines, have been determined using a curve-of-growth analysis of interstellar data from the Copernicus and International Ultraviolet Explorer (IUE) satellites. In addition to slight changes in strengths of the far-UV lines, new f-values are reported for wavelength 1608.45, a prominent line in interstellar and quasar absorption spectra, and for wavelength 2260.08, a weak, newly identified linen in IUE interstellar spectra. An upper limit on the strength of the undetected line at 2366.867 A (UV multiplet 2) is set. Using revised oscillator strengths, Fe II column densities toward 13 OB stars are derived. The interstellar depletions, (Fe/H), relative to solar values range between factors of 10 and 120.

  12. Longitudinal oscillation of launch vehicles

    NASA Technical Reports Server (NTRS)

    Glaser, R. F.

    1973-01-01

    During powered flight a vehicle may develop longitudinal self-excited oscillations, so-called oscillations, of its structure. The energy supplying the vibration is tapped from the thrust by the activity of the system itself; that is, oscillation of the structure causes oscillation of the propellant system, especially of the pumps. In this way an oscillating thrust can be created that, by a feedback loop, may sustain the structural oscillation under certain circumstances. Two special features of the system proved to be essential for creation of instability. One is the effect of the inherent time interval that the thrust oscillation is lagging behind the structural oscillation. The other is the decreased of system mass caused by the exhausting of gas. The latter feature may cause an initially stable system to become unstable. To examine the stability of the system, a single mass-spring model, which is the result of a one-term Galerkin approach to the equation of motion, has been considered. The Nyquist stability criterion leads to a stability graph that shows the stability conditions in terms of the system parameter and also demonstrates the significance of time lag, feedback magnitude, and loss of mass. An important conclusion can be drawn from the analysis: large relative displacements of the pump-engine masses favor instability. This is also confirmed by flight measurements.

  13. Fano Interference in Classical Oscillators

    ERIC Educational Resources Information Center

    Satpathy, S.; Roy, A.; Mohapatra, A.

    2012-01-01

    We seek to illustrate Fano interference in a classical coupled oscillator by using classical analogues of the atom-laser interaction. We present an analogy between the dressed state picture of coherent atom-laser interaction and a classical coupled oscillator. The Autler-Townes splitting due to the atom-laser interaction is analogous to the…

  14. Mechanical Parametric Oscillations and Waves

    ERIC Educational Resources Information Center

    Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.

    2013-01-01

    Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…

  15. Neutrino Oscillations in the Case of General Interaction

    NASA Astrophysics Data System (ADS)

    Syska, J.; Zajac, S.; Zrałek, M.

    2007-11-01

    The process of the neutrino production, oscillation in the vacuum or in matter, and detection in the case of interactions which are beyond the Standard Model is considered. Neutrino states are described by the density matrix. The final neutrino production rate does not factorize. The known Maki-Nakagawa-Sakata neutrino states and the factorized production rate are recovered in the nu SM regime.

  16. Expression by midbrain dopamine neurons of Sema3A and 3F receptors is associated with chemorepulsion in vitro but a mild in vivo phenotype.

    PubMed

    Torre, Enrique R; Gutekunst, Claire-Anne; Gross, Robert E

    2010-06-01

    Here we explore the role of semaphorin 3A and 3F (Sema3A, Sema3F) in the formation of the mesotelencephalic pathway. We show that Sema3A and 3F are expressed in the ventral mesencephalon (VM) of E13.5 rat embryos; the receptors Neuropilin 1 and Neuropilin 2, and co-receptors L1CAM, NrCAM, and Plexins A1 and A3 but not A4 are expressed by VM dopaminergic neurons; these neurons bind Sema3A and 3F in vitro which induces collapse of their growth cones and elicits, with different potencies, a repulsive response; and this response is absent in axons from Nrp1 and Nrp2 null embryos. Despite these in vitro effects, only very mild anatomical defects were detected in the organization of the mesotelencephalic pathway in embryonic and adult Nrp1 or Nrp2 null mice. However, the dopaminergic meso-habenular pathway and catecholaminergic neurons in the parafascicular and paraventricular nuclei of the thalamus were significantly affected in Nrp2 null mice. These data are consistent with a model whereby Sema3A and 3F, in combination with other guidance molecules, contributes to the navigation of DA axons to their final synaptic targets. PMID:20298787

  17. Synthesis and structure of a new layered oxyfluoride Sr{sub 2}ScO{sub 3}F with photocatalytic property

    SciTech Connect

    Wang, Yongkun; Tang, Kaibin Zhu, Baichuan; Wang, Dake; Hao, Qiaoyan; Wang, Yan

    2015-05-15

    Highlights: • A new oxyfluoride compound Sr{sub 2}ScO{sub 3}F was prepared by a solid state route. • The structure of this compound was determined by GSAS program based on XRD data. • The photocatalytic property was investigated under UV irradiation. - Abstract: A new Ruddlesden–Popper type scandium oxyfluoride, Sr{sub 2}ScO{sub 3}F, was synthesized by a conventional solid state reaction route. The detailed structure of Sr{sub 2}ScO{sub 3}F was investigated using X-ray diffraction (XRD) and selected area electron diffraction (SAED). The disorder distribution pattern of fluorine anions was determined by the {sup 19}F nuclear magnetic resonance (NMR) spectrum. The compound crystallizes in a K{sub 2}NiF{sub 4}-type tetragonal structure (space group I4/mmm) with O/F anions disordered over the apical sites of the perovskite-type Sc(O,F){sub 6} octahedron layers interleaved with strontium cations. Ultraviolet–visible (UV–vis) diffuse reflection spectrum of the prepared Sr{sub 2}ScO{sub 3}F indicates that it has an absorption in the UV–vis region. The photocatalytic activity of Sr{sub 2}ScO{sub 3}F was further investigated, showing an effective photodegradation of Rhodamine-B (RB) within 2 h under UV light irradiation.

  18. Luminescence and energy transfer in Eu2+, Mn2+ co-doped Ca2SrNaLa(PO4)3F

    NASA Astrophysics Data System (ADS)

    Shanshan, Hu; Wanjun, Tang

    2013-12-01

    A new compound Ca2SrNaLa(PO4)3F, isotypic with hexagonal Ca(Sr,Na,Ca)(Ca,Sr,Ce)3(PO4)3F, is reported. Its cell parameters have been determined from X-ray powder diffraction data. Crystallization occurs in the hexagonal space group P63 (No. 173) with a = 9.515(1) Å, c = 7.028(1) Å, and Z = 2. Eu2+ and Mn2+ activated Ca2SrNaLa(PO4)3F phosphors have been prepared. The energy transfer of Eu2+ → Mn2+ has been investigated. The resonant type energy transfer from Eu2+ to Mn2+ has been demonstrated, and the energy transfer efficiency has also been calculated according to their PL decay curves. A color-tunable emission in Ca2SrNaLa(PO4)3F phosphors can be realized by Eu2+ → Mn2+ energy transfer. White light can be achieved in a single-phased Ca2SrNaLa(PO4)3F host by co-doping Eu2+ and Mn2+ with CIE (0.32, 0.31). Our results demonstrate that the potential application of these phosphors in solid-state lighting and (or) other areas.

  19. The Translation Regulatory Subunit eIF3f Controls the Kinase-Dependent mTOR Signaling Required for Muscle Differentiation and Hypertrophy in Mouse

    PubMed Central

    Csibi, Alfredo; Cornille, Karen; Leibovitch, Marie-Pierre; Poupon, Anne; Tintignac, Lionel A.; Sanchez, Anthony M. J.; Leibovitch, Serge A.

    2010-01-01

    The mTORC1 pathway is required for both the terminal muscle differentiation and hypertrophy by controlling the mammalian translational machinery via phosphorylation of S6K1 and 4E-BP1. mTOR and S6K1 are connected by interacting with the eIF3 initiation complex. The regulatory subunit eIF3f plays a major role in muscle hypertrophy and is a key target that accounts for MAFbx function during atrophy. Here we present evidence that in MAFbx-induced atrophy the degradation of eIF3f suppresses S6K1 activation by mTOR, whereas an eIF3f mutant insensitive to MAFbx polyubiquitination maintained persistent phosphorylation of S6K1 and rpS6. During terminal muscle differentiation a conserved TOS motif in eIF3f connects mTOR/raptor complex, which phosphorylates S6K1 and regulates downstream effectors of mTOR and Cap-dependent translation initiation. Thus eIF3f plays a major role for proper activity of mTORC1 to regulate skeletal muscle size. PMID:20126553

  20. Synthesis and evaluation of new antitumor 3-aminomethyl-4,11-dihydroxynaphtho[2,3-f]indole-5,10-diones.

    PubMed

    Shchekotikhin, Andrey E; Glazunova, Valeria A; Dezhenkova, Lyubov G; Luzikov, Yuri N; Buyanov, Vladimir N; Treshalina, Helena M; Lesnaya, Nina A; Romanenko, Vladimir I; Kaluzhny, Dmitry N; Balzarini, Jan; Agama, Keli; Pommier, Yves; Shtil, Alexander A; Preobrazhenskaya, Maria N

    2014-10-30

    A series of new 3-aminomethyl-4,11-dihydroxynaphtho[2,3-f]indole-5,10-diones 6-13 bearing the cyclic diamine in the position 3 of the indole ring was synthesized. The majority of new compounds demonstrated a superior cytotoxicity than doxorubicin against a panel of mammalian tumor cells with determinants of altered drug response, that is, Pgp expression or p53 inactivation. For naphtho[2,3-f]indole-5,10-diones 6-9 bearing 3-aminopyrrolidine in the side chains, the ability to bind double-stranded DNA and inhibit topoisomerases 1 and 2 mediated relaxation of supercoiled DNA were demonstrated. Only one isomer, (R)-4,11-dihydroxy-3-((pyrrolidin-3-ylamino)methyl)-1H-naphtho[2,3-f]indole-5,10-dione (7) induced the formation of specific DNA cleavage products similar to the known topoisomerase 1 inhibitors camptothecin and indenoisoquinoline MJ-III-65, suggesting a role of the structure of the side chain of 3-aminomethylnaphtho[2,3-f]indole-5,10-diones in interaction with the target. Compound 7 demonstrated an antitumor activity in mice with P388 leukemia transplants whereas its enantiomer 6 was inactive. Thus, 3-aminomethyl derivatives of 4,11-dihydroxynaphtho[2,3-f]indole-5,10-dione emerge as a new prospective chemotype for the search of antitumor agents. PMID:25244612

  1. Interplay between Subthreshold Oscillations and Depressing Synapses in Single Neurons

    PubMed Central

    Latorre, Roberto; Torres, Joaquín J.; Varona, Pablo

    2016-01-01

    In this paper we analyze the interplay between the subthreshold oscillations of a single neuron conductance-based model and the short-term plasticity of a dynamic synapse with a depressing mechanism. In previous research, the computational properties of subthreshold oscillations and dynamic synapses have been studied separately. Our results show that dynamic synapses can influence different aspects of the dynamics of neuronal subthreshold oscillations. Factors such as maximum hyperpolarization level, oscillation amplitude and frequency or the resulting firing threshold are modulated by synaptic depression, which can even make subthreshold oscillations disappear. This influence reshapes the postsynaptic neuron’s resonant properties arising from subthreshold oscillations and leads to specific input/output relations. We also study the neuron’s response to another simultaneous input in the context of this modulation, and show a distinct contextual processing as a function of the depression, in particular for detection of signals through weak synapses. Intrinsic oscillations dynamics can be combined with the characteristic time scale of the modulatory input received by a dynamic synapse to build cost-effective cell/channel-specific information discrimination mechanisms, beyond simple resonances. In this regard, we discuss the functional implications of synaptic depression modulation on intrinsic subthreshold dynamics. PMID:26730737

  2. Interplay between Subthreshold Oscillations and Depressing Synapses in Single Neurons.

    PubMed

    Latorre, Roberto; Torres, Joaquín J; Varona, Pablo

    2016-01-01

    In this paper we analyze the interplay between the subthreshold oscillations of a single neuron conductance-based model and the short-term plasticity of a dynamic synapse with a depressing mechanism. In previous research, the computational properties of subthreshold oscillations and dynamic synapses have been studied separately. Our results show that dynamic synapses can influence different aspects of the dynamics of neuronal subthreshold oscillations. Factors such as maximum hyperpolarization level, oscillation amplitude and frequency or the resulting firing threshold are modulated by synaptic depression, which can even make subthreshold oscillations disappear. This influence reshapes the postsynaptic neuron's resonant properties arising from subthreshold oscillations and leads to specific input/output relations. We also study the neuron's response to another simultaneous input in the context of this modulation, and show a distinct contextual processing as a function of the depression, in particular for detection of signals through weak synapses. Intrinsic oscillations dynamics can be combined with the characteristic time scale of the modulatory input received by a dynamic synapse to build cost-effective cell/channel-specific information discrimination mechanisms, beyond simple resonances. In this regard, we discuss the functional implications of synaptic depression modulation on intrinsic subthreshold dynamics. PMID:26730737

  3. Neutrino oscillations in a model with a source and detector

    NASA Astrophysics Data System (ADS)

    Kiers, Ken; Weiss, Nathan

    1998-03-01

    We study the oscillations of neutrinos in a model in which the neutrino is coupled to a localized, idealized source and detector. By varying the spatial and temporal resolution of the source and detector we are able to model the full range of source and detector types ranging from coherent to incoherent. We find that this approach is useful in understanding the interface between the quantum mechanical nature of neutrino oscillations on the one hand and the production and detection systems on the other hand. This method can easily be extended to study the oscillations of other particles such as the neutral K and B mesons. We find that this approach gives a reliable way to treat the various ambiguities which arise when one examines the oscillations from a wave packet point of view. We demonstrate that the conventional oscillation formula is correct in the relativistic limit and that several recent claims of an extra factor of 2 in the oscillation length are incorrect. We also demonstrate explicitly that the oscillations of neutrinos which have separated spatially may be ``revived'' by a long coherent measurement.

  4. Surface acoustic wave stabilized oscillators

    NASA Technical Reports Server (NTRS)

    Parker, T. E.

    1978-01-01

    A number of 401.2 MHz surface acoustic wave (SAW) controlled oscillators were built and tested. The performance of these oscillators was evaluated for possible use as stable oscillators in communication systems. A short term frequency stability of better than 1 x 10 to the minus 9th power for one second was measured for the SAW oscillators. Long term frequency drift was measured and was found to be dependent on SAW design and packaging. Drift rates ranging from 15 ppm in twenty weeks to 2.5 ppm in twenty weeks were observed. Some further improvement was required. The temperature dependence of the saw oscillators was evaluated and it was concluded that some form of temperature compensation will be necessary to meet the requirements of some communication systems.

  5. Surface acoustic wave stabilized oscillators

    NASA Technical Reports Server (NTRS)

    Parker, T. E.; Lee, D. L.; Leja, I.

    1979-01-01

    Four areas of surface acoustic wave (SAW) controlled oscillators were investigated and a number of 401.2 MHz oscillators were constructed that showed improved performance. Aging studies on SAW devices packaged in HC36/U cold weld enclosures produced frequency drifts as low as 0.4 ppm in 35 weeks and drift rates well under 0.5 ppm/year. Temperature compensation circuits have substantially improved oscillator temperature stability, with a deviation of + or - 4 ppm observed over the range -45 C to + 40 C. High efficiency amplifiers were constructed for SAW oscillators and a dc to RF efficiency of 44 percent was obtained for an RF output of 25 mW. Shock and vibration tests were made on four oscillators and all survived 500 G shock pulses unchanged. Only when white noise vibration (20 Hz to 2000 Hz) levels of 20 G's rms were applied did some of the devices fail.

  6. Two-hour methyl isocyanate inhalation and 90-day recovery study in B6C3F1 mice

    SciTech Connect

    Boorman, G.A.; Uraih, L.C.; Gupta, B.N.; Bucher, J.R.

    1987-06-01

    B6C3F1 mice were exposed by inhalation to 0, 3, 10, and 30 ppm methyl isocyanate for 2 hr followed by a 90-day recovery period. Sixteen of eight (20%) male mice in the 30 ppm group died following exposure. There were no other unscheduled deaths in the mice. Five mice/sex/group were examined at 2 hr or at 1, 3, 7, 14, 28, 49, or 91 days following exposure. Chemical-related changes were restricted to the respiratory system. At 30 ppm there were extensive necrosis and erosion of the respiratory and olfactory epithelium in the nasal cavity. Severe necrosis and epithelial erosion were also found in the trachea and main bronchi. Regeneration of the mucosal epithelium occurred rapidly in the nasal cavity and airways. In the turbinates, mild incomplete olfactory epithelial regeneration persisted to day 91 in the male mice. Intraluminal fibrotic projections covered by respiratory epithelium and bronchial fibrosis were found in the major airways of the 30 ppm male and female mice by day 7. The intraluminal fibrosis persisted to day 91. In males with severe bronchial fibrosis, chronic alveolitis and atelectasis were found. In mice exposed to 3 or 10 ppm, persistent pulmonary changes were not found. These studies indicate that methyl isocyanate inhalation at or near lethal concentrations can cause persistent fibrosis of the major bronchi in mice.

  7. Toxicity and Carcinogenicity of Androstenedione in F344/N Rats and B6C3F1 Mice

    PubMed Central

    Blystone, Chad R.; Elmore, Susan A.; Witt, Kristine L.; Malarkey, David E.; Foster, Paul M.D.

    2011-01-01

    Androstenedione was marketed as a dietary supplement to increase muscle mass during training. Due to concern over long-term use, the NTP evaluated the subchronic and chronic toxicity and carcinogenicity of androstenedione in male and female F344/N rats and B6C3F1 mice. In subchronic studies, dose limiting effects were not observed. A chronic (two-year) exposure by gavage at 10, 20, or 50 mg/kg in rats and male mice, and 2, 10, or 50 mg/kg in female mice (50 mg/kg, maximum feasible dose) was conducted. Increased incidences of lung alveolar/bronchiolar adenoma and carcinoma occurred in the 20 mg/kg male rats and increases in mononuclear cell leukemia occurred in the 20 and 50 mg/kg female rats, which may have been related to androstenedione administration. In male and female mice, androstenedione was carcinogenic based upon a significant increase in hepatocellular tumors. A marginal increase in pancreatic islet cell adenomas in male (50 mg/kg) and female (2, 10, 50 mg/kg) mice was considered to be related to androstenedione administration. Interestingly, incidences of male rat Leydig cell adenomas and female rat mammary gland fibroadenomas decreased. In conclusion, androstenedione was determined to be carcinogenic in male and female mice, and may have been carcinogenic in rats. PMID:21651954

  8. Selective immunosuppression resulting from exposure to the carcinogenic congener of benzopyrene in B6C3F1 mice.

    PubMed Central

    Dean, J H; Luster, M I; Boorman, G A; Lauer, L D; Leubke, R W; Lawson, L

    1983-01-01

    B6C3F1 mice were exposed to two congeners of benzopyrene, either the carcinogen benzo(a)pyrene (B(a)P) or the non-carcinogen benzo(e)pyrene (B(e)P. Exposure of mice to B(a)P resulted in a reduced number of IgM and IgG antibody plaque forming cells (PFC) to the T-dependent (TD) antigen SRBC and IgM PFC's to the T-independent (TI) antigen LPS. The IgM response to hapten conjugated TI antigens was examined using TNP-LPS for reactivity of less mature B cells (B1) and TNP-Ficoll for more mature B cells (B2). Exposure to B(a)P severely depressed the TNP-Ficoll PFC response by up to 77% without altering the TNP-LPS response. These data indicated that exposure to B(a)P alters differentiation and antibody production in mature B cells to both TD and B2 TI antigens. No change in PFC was observed following exposure to B(e)P. Mishell-Dutton co-cultures confirmed that B cells were affected and that T helper cells or suppressor Mphi were not involved. Parameters of cell-mediated immunocompetence including delayed cutaneous hypersensitivity to KLH, allograft or tumour cell rejection and susceptibility to Listeria monocytogens were unaltered in B(a)P treated mice. PMID:6305542

  9. Wear Mechanism Maps for Magnesium Alloy AM60 and Composite AM60-9% (Al2O3)f

    NASA Astrophysics Data System (ADS)

    Ullah Khan, Muhammad Zafar

    The purpose of this work was to study the tribological behaviour of squeeze cast Mg alloy AM60 and its composite AM60-9% (Al2O3) f. Dry sliding wear tests were performed on specimens of these materials using a block-on-ring tribometer which was equipped with a COF and temperature measurement system. Wear, COF and temperature maps were constructed to illustrate the effect of temperature and COF on the wear behaviour of the Mg alloy and it's composite. Four wear regimes namely low, mild, transient and severe wear were identified. The transition from mild to severe wear regime was found to be dependent on the bulk temperature of the specimen. Oxidational wear prevailed in low and mild wear whereas plastic deformation induced wear and melt wear controlled the wear rates in transient and severe wear regimes, respectively. This study shows that the incorporation of Al2O3 fibres in AM60 alloy improved the wear resistance of the resulting composite by delaying the transition from mild to severe wear.

  10. Absorption and metabolism of triclosan after application to the skin of B6C3F1 mice.

    PubMed

    Fang, Jia-Long; Vanlandingham, Michelle; Gamboa da Costa, Gonçalo; Beland, Frederick A

    2016-05-01

    Triclosan is used as an antimicrobial agent in personal care products, household items, medical devices, and clinical settings. Humans can receive lifelong exposures to triclosan; however, data on the toxicity and carcinogenicity after topical application are lacking. This study determined the absorption, distribution, metabolism, and excretion of triclosan after application to the skin of B6C3F1 mice. [(14) C(U)]triclosan (10 or 100 mg triclosan/kg body weight) was administered topically to mice in two separate experiments: a vehicle selection experiment using propylene glycol, ethanol, and a generic cosmetic cream, and a toxicokinetic experiment. Mice were killed up to 72 h after triclosan administration, and excreta and tissues were analyzed for radioactivity. Ethanol had the best properties of the vehicles evaluated. Maximum absorption was obtained at approximately 12 h after dosing. Radioactivity appeared in the excreta and in all tissues examined, with the highest levels in the gall bladder and the lowest levels in the brain. Triclosan was metabolized to triclosan sulfate, triclosan glucuronide, 2,4-dichlorophenol, and hydroxytriclosan. The metabolite profile was tissue-dependent and the predominant route of excretion was fecal. The AUC0-∞ and the Cmax of plasma and liver in females were greater than those in males. Slightly lower absorption was observed in mice with Elizabethan collars. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 609-623, 2016. PMID:25410937

  11. PLEURAL EFFECTS OF INDIUM PHOSPHIDE IN B6C3F1 MICE: NONFIBROUS PARTICULATE INDUCED PLEURAL FIBROSIS

    PubMed Central

    Kirby, Patrick J.; Shines, Cassandra J.; Taylor, Genie J.; Bousquet, Ronald W.; Price, Herman C.; Everitt, Jeffrey I.; Morgan, Daniel L.

    2010-01-01

    The mechanism(s) by which chronic inhalation of indium phosphide (InP) particles causes pleural fibrosis is not known. Few studies of InP pleural toxicity have been conducted because of the challenges in conducting particulate inhalation exposures, and because the pleural lesions developed slowly over the 2-year inhalation study. The authors investigated whether InP (1 mg/kg) administered by a single oropharyngeal aspiration would cause pleural fibrosis in male B6C3F1 mice. By 28 days after treatment, protein and lactate dehydrogenase (LDH) were significantly increased in bronchoalveolar lavage fluid (BALF), but were unchanged in pleural lavage fluid (PLF). A pronounced pleural effusion characterized by significant increases in cytokines and a 3.7-fold increase in cell number was detected 28 days after InP treatment. Aspiration of soluble InCl3 caused a similar delayed pleural effusion; however, other soluble metals, insoluble particles, and fibers did not. The effusion caused by InP was accompanied by areas of pleural thickening and inflammation at day 28, and by pleural fibrosis at day 98. Aspiration of InP produced pleural fibrosis that was histologically similar to lesions caused by chronic inhalation exposure, and in a shorter time period. This oropharyngeal aspiration model was used to provide an initial characterization of the progression of pleural lesions caused by InP. PMID:19995279

  12. Electronic structures and optical properties of Ca5(BO3)3F: a systematical first-principles study.

    PubMed

    Hu, Chun-Li; Xu, Xiang; Sun, Chuan-Fu; Mao, Jiang-Gao

    2011-10-01

    A first-principles study of the electronic structure, the linear optical properties and second-order NLO properties of calcium fluoroborate (Ca(5)(BO(3))(3)F, or CBF) crystal has been performed within density functional theory and the independent-particle approximation. The results indicate that the calculated birefringence Δn and the second-order susceptibilities are very coincident with the experimental measured values, and the χ((2)) curves show stronger anisotropy than the linear optical properties. Further analysis based on the spectral and spatial decomposition of χ((2)) reveals that the main sources of the SHG response of CBF are from the planar BO(3) groups (74%-77%) and Ca(2+) cations (23%-26%) and can be attributed to the interband electronic transition from the nonbonding O 2p states to the B 2p and Ca 4s4p states. The packing arrangement of BO(3) is the principal contributor to the significant differences among SHG tensors in CBF. Meanwhile, for a certain crystal CBF, the SHG tensors' trend can be the trend of the optical transition matrix elements, which are high when the corresponding subscript directions have more parallel BO(3) triangular planes in the structure. PMID:21918290

  13. Spectroscopy and Calculations for f-f Transitions of Tb3+ Ions in KY3F10 Nanocrystal.

    PubMed

    Zhang, Jinsu; Chen, Baojiu; Sun, Jiashi; Li, Xiangping; Cheng, Lihong; Zhong, Haiyang

    2015-06-01

    A modified Judd-Ofelt theory is used in this paper to treat the electric dipole transitions within the 4f8 configuration of Tb3+ by considering the main perturbing components. Through the energy-level calculation and the strandard tensorial analysis, the explicit distances between the 4f7 5d configuration and the 5D4 state and other lower 4f8 energy levels are determined. The rare-earth ion Tb3+ substituted at Y3+ sites in KY3F10 has the site symmetry of C4v. The standard Judd-Ofelt parameters A2(10), A2(30), A4(30), A4(50), A6(50), A4(54) and A6(54) are included in the calculation together with odd-λ parameters A1(10), A3(30), A5(50) and A5(54). The fluorescence branching ratios originating from 5D4 are calculated. Compared with the experimental measurements, the modified model yields better results than the standard Judd-Ofelt theory. PMID:26369102

  14. Toxicology studies of a chemical mixture of 25 groundwater contaminants. II. Immunosuppression in B6C3F1 mice

    SciTech Connect

    Germolec, D.R.; Yang, R.S.; Ackermann, M.F.; Rosenthal, G.J.; Boorman, G.A.; Blair, P.; Luster, M.I. )

    1989-10-01

    Concern over the potential adverse health effects of chemically contaminated groundwater has existed for many years. In general, these studies have focused on retrospective epidemiological studies for cancer risk. In the present studies, immune function was monitored in female B6C3F1 mice exposed to a chemical mixture in drinking water for either 14 or 90 days. The mixture consisted of 25 common groundwater contaminants frequently found near toxic waste dumps, as determined by EPA surveys. None of the animals developed overt signs of toxicity such as body or liver weight changes. Mice exposed to the highest dose of this mixture for 14 or 90 days showed immune function changes which could be related to rapidly proliferating cells, including suppression of hematopoietic stem cells and of antigen-induced antibody-forming cells. Some of these responses, e.g., granulocyte-macrophage colony formation, were also suppressed at lower concentrations of the chemical mixture. There were no effects on T cell function or T and B cell numbers in any of the treatment groups. Altered resistance to challenge with an infectious agent also occurred in mice given the highest concentration, which correlated with the immune function changes. Paired-water studies indicated that the immune effects were related to chemical exposure and not to decreased water intake. These results suggest that long-term exposure to contaminated groundwater may represent a risk to the immune system in humans.

  15. Investigation of third-order optical nonlinearity in KBe2BO3F2 crystal by Z-scan

    NASA Astrophysics Data System (ADS)

    Li, F.-Q.; Zong, N.; Zhang, F.-F.; Yang, J.; Yang, F.; Peng, Q.-J.; Cui, D.-F.; Zhang, J.-Y.; Wang, X.-Y.; Chen, C.-T.; Xu, Z.-Y.

    2012-08-01

    The third-order optical nonlinearity of deep-ultraviolet (DUV) nonlinear optical (NLO) crystal KBe2BO3F2 (KBBF) was investigated using single-beam Z-scan technique for the first time. The Z-scans were performed on a c-cut KBBF crystal and a KBBF prism-coupling device (PCD) with picosecond pulses at 355 nm. No two-photon absorption was observed in the experiment. The measured nonlinear refraction index n 2 showed positive signs, indicating self-focusing Kerr effects. The n 2 values were estimated to be (1.75±0.35)×10-15 cm2/W with the c-cut sample and (1.85±0.37)×10-15 cm2/W with the PCD, corresponding to the third-order nonlinear optical susceptibilities χ_{eff}^{(3)} of (0.99±0.20)×10-13 esu and (0.94±0.19)×10-13 esu, respectively. The results are expected to promote the investigation of frequency conversion processes with ultra-short laser in KBBF crystal.

  16. Vertical Spin Current Injection induced Domain Wall Oscillations

    NASA Astrophysics Data System (ADS)

    Sharma, Sanchar; Muralidharan, Bhaskaran; Tulapurkar, Ashwin

    2015-03-01

    We present a novel oscillator based on domain wall motion using vertical spin current injection and an external magnetic field above the Walker breakdown. We numerically simulate 1D Landau-Lifshitz-Gilbert equation to extract the oscillation parameters such as the amplitude, the frequency and the Q-factor, as a function of the inputs. We also provide a theoretical analysis using rigid domain walls and find an approximate waveform for the oscillations. We find that the oscillation frequency is twice the resonant frequency of a magnet in an applied magnetic field; while the amplitude is approximately a linear function of the ratio of the demagnetization field and the applied magnetic field. Both of them are independent of input current and other material parameters to a very good degree of accuracy; and hence can be of great technological advantage for accurate oscillatory waveforms.

  17. Oscillating flow loss test results in Stirling engine heat exchangers

    NASA Technical Reports Server (NTRS)

    Koester, G.; Howell, S.; Wood, G.; Miller, E.; Gedeon, D.

    1990-01-01

    The results are presented for a test program designed to generate a database of oscillating flow loss information that is applicable to Stirling engine heat exchangers. The tests were performed on heater/cooler tubes of various lengths and entrance/exit configurations, on stacked and sintered screen regenerators of various wire diameters and on Brunswick and Metex random fiber regenerators. The test results were performed over a range of oscillating flow parameters consistent with Stirling engine heat exchanger experience. The tests were performed on the Sunpower oscillating flow loss rig which is based on a variable stroke and variable frequency linear drive motor. In general, the results are presented by comparing the measured oscillating flow losses to the calculated flow losses. The calculated losses are based on the cycle integration of steady flow friction factors and entrance/exit loss coefficients.

  18. Atomic hydrogen maser active oscillator cavity and bulb design optimization

    NASA Technical Reports Server (NTRS)

    Peters, H. E.; Washburn, P. J.

    1984-01-01

    The performance characteristics and reliability of the active oscillator atomic hydrogen maser depend upon oscillation parameters which characterize the interaction region of the maser, the resonant cavity and atom storage bulb assembly. With particular attention to use of the cavity frequency switching servo (1) to reduce cavity pulling, it is important to maintain high oscillation level, high atomic beam flux utilization efficiency, small spin exchange parameter and high cavity quality factor. It is also desirable to have a small and rigid cavity and bulb structure and to minimize the cavity temperature sensitivity. Curves for a novel hydrogen maser cavity configuration which is partially loaded with a quartz dielectric cylinder and show the relationships between cavity length, cavity diameter, bulb size, dielectric thickness, cavity quality factor, filling factor and cavity frequency temperature coefficient are presented. The results are discussed in terms of improvement in maser performance resulting from particular design choices.

  19. Diagnostic value of H3F3A mutations in giant cell tumour of bone compared to osteoclast‐rich mimics

    PubMed Central

    Presneau, Nadège; Baumhoer, Daniel; Behjati, Sam; Pillay, Nischalan; Tarpey, Patrick; Campbell, Peter J; Jundt, Gernot; Hamoudi, Rifat; Wedge, David C; Loo, Peter Van; Hassan, A Bassim; Khatri, Bhavisha; Ye, Hongtao; Tirabosco, Roberto; Amary, M Fernanda

    2015-01-01

    Abstract Driver mutations in the two histone 3.3 (H3.3) genes, H3F3A and H3F3B, were recently identified by whole genome sequencing in 95% of chondroblastoma (CB) and by targeted gene sequencing in 92% of giant cell tumour of bone (GCT). Given the high prevalence of these driver mutations, it may be possible to utilise these alterations as diagnostic adjuncts in clinical practice. Here, we explored the spectrum of H3.3 mutations in a wide range and large number of bone tumours (n = 412) to determine if these alterations could be used to distinguish GCT from other osteoclast‐rich tumours such as aneurysmal bone cyst, nonossifying fibroma, giant cell granuloma, and osteoclast‐rich malignant bone tumours and others. In addition, we explored the driver landscape of GCT through whole genome, exome and targeted sequencing (14 gene panel). We found that H3.3 mutations, namely mutations of glycine 34 in H3F3A, occur in 96% of GCT. We did not find additional driver mutations in GCT, including mutations in IDH1, IDH2, USP6, TP53. The genomes of GCT exhibited few somatic mutations, akin to the picture seen in CB. Overall our observations suggest that the presence of H3F3A p.Gly34 mutations does not entirely exclude malignancy in osteoclast‐rich tumours. However, H3F3A p.Gly34 mutations appear to be an almost essential feature of GCT that will aid pathological evaluation of bone tumours, especially when confronted with small needle core biopsies. In the absence of H3F3A p.Gly34 mutations, a diagnosis of GCT should be made with caution.

  20. Semaphorin 3F Is a Bifunctional Guidance Cue for Dopaminergic Axons and Controls Their Fasciculation, Channeling, Rostral Growth, and Intracortical Targeting

    PubMed Central

    Kolk, Sharon M.; Gunput, Rou-Afza F.; Tran, Tracy S.; van den Heuvel, Dianne M. A.; Prasad, Asheeta A.; Hellemons, Anita J. C. G. M.; Adolfs, Youri; Ginty, David D.; Kolodkin, Alex L.; Burbach, J. Peter H.; Smidt, Marten P.; Pasterkamp, R. Jeroen

    2010-01-01

    Dopaminergic neurons in the mesodiencephalon (mdDA neurons) make precise synaptic connections with targets in the forebrain via the mesostriatal, mesolimbic, and mesoprefrontal pathways. Because of the functional importance of these remarkably complex ascending axon pathways and their implication in human disease, the mechanisms underlying the development of these connections are of considerable interest. Despite extensive in vitro studies, the molecular determinants that ensure the perfect formation of these pathways in vivo remain mostly unknown. Here, we determine the embryonic origin and ontogeny of the mouse mesoprefrontal pathway and use these data to reveal an unexpected requirement for semaphorin 3F (Sema3F) and its receptor neuropilin-2 (Npn-2) during mdDA pathway development using tissue culture approaches and analysis of sema3F−/−, npn-2−/−, and npn-2−/−;TH-Cre mice. We show that Sema3F is a bifunctional guidance cue for mdDA axons, some of which have the remarkable ability to regulate their responsiveness to Sema3F as they develop. During early developmental stages, Sema3F chemorepulsion controls previously uncharacterized aspects of mdDA pathway development through both Npn-2-dependent (axon fasciculation and channeling) and Npn-2-independent (rostral growth) mechanisms. Later on, chemoattraction mediated by Sema3F and Npn-2 is required to orient mdDA axon projections in the cortical plate of the medial prefrontal cortex. This latter finding demonstrates that regulation of axon orientation in the target field occurs by chemoattractive mechanisms, and this is likely to also apply to other neural systems. In all, this study provides a framework for additional dissection of the molecular basis of mdDA pathway development and disease. PMID:19812329

  1. A theory of generalized Bloch oscillations

    NASA Astrophysics Data System (ADS)

    Duggen, Lars; Voon, L. C. Lew Yan; Lassen, Benny; Willatzen, Morten

    2016-04-01

    Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact calculation is given to confirm this phenomenon. Our results allow for a greater freedom of design for experimentally observing Bloch oscillations. For strongly coupled oscillator systems displaying Bloch oscillations, it is further demonstrated that reordering of oscillators leads to destruction of Bloch oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics.

  2. Relaxation damping in oscillating contacts

    PubMed Central

    Popov, M.; Popov, V.L.; Pohrt, R.

    2015-01-01

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect “relaxation damping”. The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed. PMID:26549011

  3. Relaxation damping in oscillating contacts

    NASA Astrophysics Data System (ADS)

    Popov, M.; Popov, V. L.; Pohrt, R.

    2015-11-01

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect “relaxation damping”. The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed.

  4. CORONAL LOOP OSCILLATIONS OBSERVED WITH ATMOSPHERIC IMAGING ASSEMBLY-KINK MODE WITH CROSS-SECTIONAL AND DENSITY OSCILLATIONS

    SciTech Connect

    Aschwanden, Markus J.; Schrijver, Carolus J.

    2011-08-01

    A detailed analysis of a coronal loop oscillation event is presented, using data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO) for the first time. The loop oscillation event occurred on 2010 October 16, 19:05-19:35 UT and was triggered by an M2.9 GOES-class flare, located inside a highly inclined cone of a narrow-angle coronal mass ejection. This oscillation event had a number of unusual features: (1) excitation of kink-mode oscillations in vertical polarization (in the loop plane), (2) coupled cross-sectional and density oscillations with identical periods, (3) no detectable kink amplitude damping over the observed duration of four kink-mode periods (P=6.3 minutes), (4) multi-loop oscillations with slightly ({approx}10%) different periods, and (5) a relatively cool loop temperature of T {approx} 0.5 MK. We employ a novel method of deriving the electron density ratio external and internal to the oscillating loop from the ratio of Alfvenic speeds deduced from the flare trigger delay and the kink-mode period, i.e., n{sub e} /n{sub i} = (v{sub A} /v{sub Ae}){sup 2} = 0.08 {+-} 0.01. The coupling of the kink mode and cross-sectional oscillations can be explained as a consequence of the loop length variation in the vertical polarization mode. We determine the exact footpoint locations and loop length with stereoscopic triangulation using STEREO/EUVI/A data. We model the magnetic field in the oscillating loop using Helioseismic and Magnetic Imager/SDO magnetogram data and a potential-field model and find agreement with the seismological value of the magnetic field, B{sub kink} = 4.0 {+-} 0.7 G, within a factor of two.

  5. Theory of Mitotic Spindle Oscillations

    NASA Astrophysics Data System (ADS)

    Grill, Stephan W.; Kruse, Karsten; Jülicher, Frank

    2005-03-01

    During unequal cell division the mitotic spindle is positioned away from the center of the cell before cell cleavage. In many biological systems this repositioning is accompanied by oscillatory movements of the spindle. We present a theoretical description for mitotic spindle oscillations. We show that the cooperative attachment and detachment of cortical force generators to astral microtubules leads to spontaneous oscillations beyond a critical number of force generators. This mechanism can quantitatively describe the spindle oscillations observed during unequal division of the one cell stage Caenorhabditis elegans embryo.

  6. VOLTAGE-CONTROLLED TRANSISTOR OSCILLATOR

    DOEpatents

    Scheele, P.F.

    1958-09-16

    This patent relates to transistor oscillators and in particular to those transistor oscillators whose frequencies vary according to controlling voltages. A principal feature of the disclosed transistor oscillator circuit resides in the temperature compensation of the frequency modulating stage by the use of a resistorthermistor network. The resistor-thermistor network components are selected to have the network resistance, which is in series with the modulator transistor emitter circuit, vary with temperature to compensate for variation in the parameters of the transistor due to temperature change.

  7. Forced synchronization of quasiperiodic oscillations

    NASA Astrophysics Data System (ADS)

    Stankevich, N. V.; Kurths, J.; Kuznetsov, A. P.

    2015-01-01

    A model of a generator of quasiperiodic oscillations forced by a periodic pulse sequence is studied. We analyze synchronization when the autonomous generator demonstrates periodic, quasiperiodic, respective weakly chaotic oscillations. For the forced quasiperiodic oscillations a picture of synchronization, consisting of small-scale and large-scale structures was uncovered. It even includes the existence of stable the three-frequency tori. For the regime of weak chaos a partial destruction of this features and of the regime of three-frequency tori are found.

  8. Analyzing Atmospheric Neutrino Oscillations

    SciTech Connect

    Escamilla, J.; Ernst, D. J.; Latimer, D. C.

    2007-10-26

    We provide a pedagogic derivation of the formula needed to analyze atmospheric data and then derive, for the subset of the data that are fully-contained events, an analysis tool that is quantitative and numerically efficient. Results for the full set of neutrino oscillation data are then presented. We find the following preliminary results: 1.) the sub-dominant approximation provides reasonable values for the best fit parameters for {delta}{sub 32}, {theta}{sub 23}, and {theta}{sub 13} but does not quantitatively provide the errors for these three parameters; 2.) the size of the MSW effect is suppressed in the sub-dominant approximation; 3.) the MSW effect reduces somewhat the extracted error for {delta}{sub 32}, more so for {theta}{sub 23} and {theta}{sub 13}; 4.) atmospheric data alone constrains the allowed values of {theta}{sub 13} only in the sub-dominant approximation, the full three neutrino calculations requires CHOOZ to get a clean constraint; 5.) the linear in {theta}{sub 13} terms are not negligible; and 6.) the minimum value of {theta}{sub 13} is found to be negative, but at a statistically insignificant level.

  9. Sawtooth oscillation in tokamaks

    SciTech Connect

    Park, W.; Monticello, D.A.

    1989-03-01

    A three-dimensional nonlinear toroidal full MHD code, MH3D, has been used to study sawtooth oscillations in tokamaks. The profile evolution during the sawtooth crash phase compares well with experiment, but only if neoclassical resistivity is used in the rise phase. (Classical resistivity has been used in most of the previous theoretical sawtooth studies.) With neoclassical resistivity, the q value at the axis drops from 1 to about 0.8 before the crash phase, and then resets to 1 through a Kadomtsev-type complete reconnection process. This ..delta..q/sub 0/ approx. = 0.2 is much larger than ..delta..q/sub o/ approx. = 0.01, which is obtained if classical resistivity is used. The current profile is strongly peaked at the axis with a flat region around the singular surface, and is similar to the Textor profile. To understand this behavior, approximate formulas for the time behavior of current and q values are derived. A functional dependence of sawtooth period scaling is also derived. A semi-empirical scaling is found which fits the experimental data from various tokamaks. Some evidence is presented which indicates that the fast crash time is due to enhanced effective resistivity inside the singular current sheet, generated by, e.g., microinstability and electron parallel viscosity with stochastic fields at the x-point. 16 refs., 5 figs.

  10. Galactic oscillator symmetry

    NASA Technical Reports Server (NTRS)

    Rosensteel, George

    1995-01-01

    Riemann ellipsoids model rotating galaxies when the galactic velocity field is a linear function of the Cartesian coordinates of the galactic masses. In nuclear physics, the kinetic energy in the linear velocity field approximation is known as the collective kinetic energy. But, the linear approximation neglects intrinsic degrees of freedom associated with nonlinear velocity fields. To remove this limitation, the theory of symplectic dynamical symmetry is developed for classical systems. A classical phase space for a self-gravitating symplectic system is a co-adjoint orbit of the noncompact group SP(3,R). The degenerate co-adjoint orbit is the 12 dimensional homogeneous space Sp(3,R)/U(3), where the maximal compact subgroup U(3) is the symmetry group of the harmonic oscillator. The Hamiltonian equations of motion on each orbit form a Lax system X = (X,F), where X and F are elements of the symplectic Lie algebra. The elements of the matrix X are the generators of the symplectic Lie algebra, viz., the one-body collective quadratic functions of the positions and momenta of the galactic masses. The matrix F is composed from the self-gravitating potential energy, the angular velocity, and the hydostatic pressure. Solutions to the hamiltonian dynamical system on Sp(3,R)/U(3) are given by symplectic isospectral deformations. The Casimirs of Sp(3,R), equal to the traces of powers of X, are conserved quantities.

  11. Coherent microwave generation by spintronic feedback oscillator.

    PubMed

    Kumar, Dinesh; Konishi, K; Kumar, Nikhil; Miwa, S; Fukushima, A; Yakushiji, K; Yuasa, S; Kubota, H; Tomy, C V; Prabhakar, A; Suzuki, Y; Tulapurkar, A

    2016-01-01

    The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ. Any fluctuation of the free layer magnetization is converted into oscillating voltage via the tunneling magneto-resistance effect and is fed back into the MTJ by the CPW through inductive coupling. As a result of this feedback, the magnetization of the free layer can be driven into a continual precession. The combination of MTJ and CPW behaves similar to a laser system and outputs a stable rf power with quality factor exceeding 10,000. PMID:27478134

  12. Coherent microwave generation by spintronic feedback oscillator

    PubMed Central

    Kumar, Dinesh; Konishi, K.; Kumar, Nikhil; Miwa, S.; Fukushima, A.; Yakushiji, K.; Yuasa, S.; Kubota, H.; Tomy, C. V.; Prabhakar, A.; Suzuki, Y.; Tulapurkar, A.

    2016-01-01

    The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ. Any fluctuation of the free layer magnetization is converted into oscillating voltage via the tunneling magneto-resistance effect and is fed back into the MTJ by the CPW through inductive coupling. As a result of this feedback, the magnetization of the free layer can be driven into a continual precession. The combination of MTJ and CPW behaves similar to a laser system and outputs a stable rf power with quality factor exceeding 10,000. PMID:27478134

  13. Local oscillator distribution using a geostationary satellite

    NASA Technical Reports Server (NTRS)

    Bardin, Joseph; Weinreb, Sander; Bagri, Durga

    2004-01-01

    A satellite communication system suitable for distribution of local oscillator reference signals for a widely spaced microwave array has been developed and tested experimentally. The system uses a round-trip correction method of the satellite This experiment was carried out using Telstar-5, a commercial Ku-band geostationary satellite. For this initial experiment, both earth stations were located at the same site to facilitate direct comparison of the received signals. The local oscillator reference frequency was chosen to be 300MHz and was sent as the difference between two Ku-band tones. The residual error after applying the round trip correction has been measured to be better than 3psec for integration times ranging from 1 to 2000 seconds. For integration times greater then 500 seconds, the system outperforms a pair of hydrogen masers with the limitation believed to be ground-based equipment phase stability. The idea of distributing local oscillators using a geostationary satellite is not new; several researchers experimented with this technique in the eighties, but the achieved accuracy was 3 to 100 times worse than the present results. Since substantially and the performance of various components has improved. An important factor is the leasing of small amounts of satellite communication bandwidth. We lease three 100kHz bands at approximately one hundredth the cost of a full 36 MHz transponder. Further tests of the system using terminal separated by large distances and comparison tests with two hydrogen masers and radio interferometry is needed.

  14. Calibration of the Oscillating Screen Viscometer

    NASA Technical Reports Server (NTRS)

    Berg, Robert F.; Moldover, Michael R.

    1993-01-01

    We have devised a calibration procedure for the oscillating screen viscometer which can provide the accuracy needed for the flight measurement of viscosity near the liquid-vapor critical point of xenon. The procedure, which makes use of the viscometer's wide bandwidth and hydrodynamic similarity, allows the viscometer to be self-calibrating. To demonstrate the validity of this procedure we measured the oscillator's transfer function under a wide variety of conditions. We obtained data using CO2 at temperatures spanning a temperature range of 35 K and densities varying by a factor of 165, thereby encountering viscosity variations as great as 50%. In contrast the flight experiment will be performed over a temperature range of 29 K and at only a single density, and the viscosity is expected to change by less than 40%. The measurements show that, after excluding data above 10 Hz (where frequency-dependent corrections are poorly modeled) and making a plausible adjustment to the viscosity value used at high density, the viscometer's behavior is fully consistent with the use of hydrodynamic similarity for calibration. Achieving this agreement required understanding a 1% anelastic effect present in the oscillator's torsion fiber.

  15. Coherent microwave generation by spintronic feedback oscillator

    NASA Astrophysics Data System (ADS)

    Kumar, Dinesh; Konishi, K.; Kumar, Nikhil; Miwa, S.; Fukushima, A.; Yakushiji, K.; Yuasa, S.; Kubota, H.; Tomy, C. V.; Prabhakar, A.; Suzuki, Y.; Tulapurkar, A.

    2016-08-01

    The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ. Any fluctuation of the free layer magnetization is converted into oscillating voltage via the tunneling magneto-resistance effect and is fed back into the MTJ by the CPW through inductive coupling. As a result of this feedback, the magnetization of the free layer can be driven into a continual precession. The combination of MTJ and CPW behaves similar to a laser system and outputs a stable rf power with quality factor exceeding 10,000.

  16. Promotion of hepatic preneoplastic lesions in male B6C3F{sub 1} mice by unleaded gasoline

    SciTech Connect

    Standeven, A.M.; Wolf, D.C.; Goldsworthy, T.L.

    1995-07-01

    In previous studies, unleaded gasoline (UG) vapor was found to be a liver tumor promotor and hepatocarcinogen in female mice, but UG was not a hepatocarcinogen in male mice. However, UG vapor had similar transient mitogenic effects in nonlesioned liver of both male and female mice under the conditions of the cancer bioassay. We used an initiation-promotion protocol to determine whether UG vapor acts as a liver tumor promoter in male mice and to examine proliferative effects that may be critical to tumor development. Twelve-day-old male B6C3F{sub 1} mice were injected with N-nitrosodiethylamine (DEN; 5 mg/kg, intraperitoneally) or vehicle. Starting at 5-7 weeks of age, mice were exposed by inhalation 6 hr/day, 5 days/week for 16 weeks to 0 or 2046 ppm of PS-6 blend UG. UG treatment caused a significant 2.3-fold increase in the number of macroscopic hepatic masses in DEN-initiated mice, whereas no macroscopic masses were observed in noninitiated mice. To study hepatocyte proliferative effects of UG, we treated mice with 5-bromo-2`-deoxyuridine (BrdU) via osmotic pump for 3 days before necropsy and measured hepatocyte BruU labeling index (LI) in AHF and nonlesioned liver. UG did not significantly affect BrdU LI in nonlesioned liver. However, hepatocyte LI in AHF was about 30% higher in DEN/UG-treated mice relative to mice treated with DEN alone. These data show that UG vapor promotes AHF in male mice and that liver tumor promotion is associated with a selective increase in hepatocyte proliferation in AHF. UG acts as a liver tumor promoter in both male and female mice, and these findings contrast with the lack of hepatocarcinogenicity of UG in male mice in a cancer bioassy. 36 refs., 1 fig., 3 tabs.

  17. Characterization of uterine granular cell tumors in B6C3F1 mice: a histomorphologic, immunohistochemical, and ultrastructural study.

    PubMed

    Veit, A C; Painter, J T; Miller, R A; Hardisty, J F; Dixon, D

    2008-09-01

    The granular cell tumor is most often a benign neoplasm of uncertain origin. Four uterine granular cell tumors in control and treated female B6C3F1 mice were identified in chronic studies at the National Toxicology Program. Two tumors occurred in untreated control animals and 2 in treated animals receiving different compounds. Tissue sections were evaluated histologically and stained with hematoxylin and eosin, periodic acid-Schiff with diastase resistance, Masson's trichrome, toluidine blue, phosphotungstic acid-hematoxylin, and stained immunohistochemically with a panel of antibodies to muscle (desmin, alpha smooth muscle actin), neural (S-100, neuron specific enolase), epithelial (wide-spectrum cytokeratin), and macrophage (F4/80) markers. The main histomorphologic feature of tumor cells was the presence of abundant cytoplasmic eosinophilic granules that stained positive for periodic acid-Schiff with diastase resistance. Tumors varied in appearance and were comprised of sheets and nests of round to polygonal cells with distinct borders. Nuclei were hyperchromatic, pleomorphic, and centrally to eccentrically located and often contained single nucleoli. Occasional multinucleated giant cells were observed. Tumors were pale pink and homogeneous with trichrome stain and negative with toluidine blue. Three tumors had positive to weakly positive immunoreactivity for desmin, and 1 was positive for alpha smooth muscle actin. Expression of S-100, wide-spectrum cytokeratin, and neuron-specific enolase was negative for all tumors. Ultrastructurally, prominent electron-dense cytoplasmic granules were abundant and contained secondary lysosomes with heterogeneous lysosomal contents. The characteristics of these uterine granular cell tumors were suggestive of a myogenic origin. PMID:18725470

  18. Trichloroethylene-Induced Gene Expression and DNA Methylation Changes in B6C3F1 Mouse Liver

    PubMed Central

    Tong, Jian; Chen, Tao

    2014-01-01

    Trichloroethylene (TCE), widely used as an organic solvent in the industry, is a common contaminant in air, soil, and water. Chronic TCE exposure induced hepatocellular carcinoma in mice, and occupational exposure in humans was suggested to be associated with liver cancer. To understand the role of non-genotoxic mechanism(s) for TCE action, we examined the gene expression and DNA methylation changes in the liver of B6C3F1 mice orally administered with TCE (0, 100, 500 and 1000 mg/kg b.w. per day) for 5 days. After 5 days TCE treatment at a dose level of 1000 mg/kg b.w., a total of 431 differentially expressed genes were identified in mouse liver by microarray, of which 291 were up-regulated and 140 down-regulated. The expression changed genes were involved in key signal pathways including PPAR, proliferation, apoptosis and homologous recombination. Notably, the expression level of a number of vital genes involved in the regulation of DNA methylation, such as Utrf1, Tet2, DNMT1, DNMT3a and DNMT3b, were dysregulated. Although global DNA methylation change was not detected in the liver of mice exposed to TCE, the promoter regions of Cdkn1a and Ihh were found to be hypo- and hypermethylated respectively, which correlated negatively with their mRNA expression changes. Furthermore, the gene expression and DNA methylation changes induced by TCE were dose dependent. The overall data indicate that TCE exposure leads to aberrant DNA methylation changes, which might alter the expression of genes involved in the TCE-induced liver tumorgenesis. PMID:25549359

  19. Molecular noise induces concentration oscillations in chemical systems with stable node steady states

    NASA Astrophysics Data System (ADS)

    Toner, D. L. K.; Grima, R.

    2013-02-01

    It is well known that internal or molecular noise induces concentration oscillations in chemical systems whose deterministic models exhibit damped oscillations. In this article we show, using the linear-noise approximation of the chemical master equation, that noise can also induce oscillations in systems whose deterministic descriptions admit no damped oscillations, i.e., systems with a stable node. This non-intuitive phenomenon is remarkable since, unlike noise-induced oscillations in systems with damped deterministic oscillations, it cannot be explained by noise excitation of the deterministic resonant frequency of the system. We here prove the following general properties of stable-node noise-induced oscillations for systems with two species: (i) the upper bound of their frequency is given by the geometric mean of the real eigenvalues of the Jacobian of the system, (ii) the upper bound of the Q-factor of the oscillations is inversely proportional to the distance between the real eigenvalues of the Jacobian, and (iii) these oscillations are not necessarily exhibited by all interacting chemical species in the system. The existence and properties of stable-node oscillations are verified by stochastic simulations of the Brusselator, a cascade Brusselator reaction system, and two other simple chemical systems involving auto-catalysis and trimerization. It is also shown how external noise induces stable node oscillations with different properties than those stimulated by internal noise.

  20. A quasioptically stabilized resonant-tunneling-diode oscillator for the millimeter- and submillimeter-wave regions

    NASA Technical Reports Server (NTRS)

    Brown, Elliott R.; Parker, Christopher D.; Molvar, Karen M.; Stephan, Karl D.

    1992-01-01

    A semiconfocal open-cavity resonator has been used to stabilize a resonant-tunneling-diode waveguide oscillator at frequencies near 100 GHz. The high quality factor of the open cavity resulted in a linewidth of approximately 10 kHz at 10 dB below the peak, which is about 100 times narrower than the linewidth of an unstabilized waveguide oscillator. This technique is well suited for resonant-tunneling-diode oscillators in the submillimeter-wave region.

  1. Giant resonance tuning of micro and nanomechanical oscillators

    PubMed Central

    Vitorino, Miguel V.; Carpentier, Simon; Panzarella, Alain; Rodrigues, Mario S.; Costa, Luca

    2015-01-01

    We present a method to tune the resonance frequency and the Q-factor of micro and nano-metric mechanical oscillators. A counteracting loop drives a capacitive force applied to the oscillator. The proportional and differential gains are used to shift the resonance frequency up to 75% and to tune the Q-factor of the oscillator, by changing its effective stiffness and damping ratio. The oscillator position is monitored in a large bandwidth with a fiber-optic based interferometer. We applied this simple operational scheme with different oscillators for modifying easily their dynamical properties. Compared to alternative methods requiring external fields, our method can either increase or decrease the resonance frequency in a frequency range much more extended. This opens up a wide range of applications, from force sensors with extremely low elastic constants but high quality factor to tunable energy harvesters or to high-frequency tuning of radio frequency filters. The control scheme can work in different media, and is then suitable to be applied to biological sensors and actuators. PMID:25588846

  2. Dynamics of hierarchical Brownian oscillators

    NASA Astrophysics Data System (ADS)

    Knapp, E. W.

    1988-11-01

    Two hierarchical Brownian oscillator models are introduced by using a discretized Brownian oscillator model. The dynamical behavior of these models is solved exactly. Closed-form expressions for the intermediate scattering function and the energy relaxation function governing the frequency-dependent specific heat are given. A general relationship between the two relaxation functions is established. The case of a rectangular distribution of activation energies for the different hierarchy levels of the oscillator is considered in more detail. There the energy relaxation function decays with a logarithmic slope and the intermediate scattering function exhibits an algebraic long-time decay. The two hierarchical Brownian oscillator models have the same dynamical behavior though they possess a quite different coupling scheme.

  3. Brain oscillations in neuropsychiatric disease.

    PubMed

    Başar, Erol

    2013-09-01

    The term "brain (or neural) oscillations" refers to the rhythmic and/or repetitive electrical activity generated spontaneously and in response to stimuli by neural tissue in the central nervous system. The importance of brain oscillations in sensory-cognitive processes has become increasingly evident. It has also become clear that event-related oscillations are modified in many types of neuropathology, in particular in cognitive impairment. This review discusses methods such as evoked/event-related oscillations and spectra, coherence analysis, and phase locking. It gives examples of applications of essential methods and concepts in bipolar disorder that provide a basis for fundamental notions regarding neurophysiologic biomarkers in cognitive impairment. The take-home message is that in the development of diagnostic and pharmacotherapeutic strategies, neurophysiologic data should be analyzed in a framework that uses a multiplicity of methods and frequency bands. PMID:24174901

  4. Transient voltage oscillations in coils

    SciTech Connect

    Chowdhuri, P.

    1985-01-01

    Magnet coils may be excited into internal voltage oscillations by transient voltages. Such oscillations may electrically stress the magnet's dielectric components to many times its normal stress. This may precipitate a dielectric failure, and the attendant prolonged loss of service and costly repair work. Therefore, it is important to know the natural frequencies of oscillations of a magnet during the design stage, and to determine whether the expected switching transient voltages can excite the magnet into high-voltage internal oscillations. The series capacitance of a winding significantly affects its natural frequencies. However, the series capacitance is difficult to calculate, because it may comprise complex capacitance network, consisting of intra- and inter-coil turn-to-turn capacitances of the coil sections. A method of calculating the series capacitance of a winding is proposed. This method is rigorous but simple to execute. The time-varying transient voltages along the winding are also calculated.

  5. Results from Neutrino Oscillations Experiments

    SciTech Connect

    Aguilar-Arevalo, Alexis

    2010-09-10

    The interpretation of the results of early solar and atmospheric neutrino experiments in terms of neutrino oscillations has been verified by several recent experiments using both, natural and man-made sources. The observations provide compelling evidence in favor of the existence of neutrino masses and mixings. These proceedings give a general description of the results from neutrino oscillation experiments, the current status of the field, and some possible future developments.

  6. Wavelet Analysis of Umbral Oscillations

    NASA Astrophysics Data System (ADS)

    Christopoulou, E. B.; Skodras, A.; Georgakilas, A. A.; Koutchmy, S.

    2003-07-01

    We study the temporal behavior of the intensity and velocity chromospheric umbral oscillations, applying wavelet analysis techniques to four sets of observations in the Hα line and one set of simultaneous observations in the Hα and the nonmagnetic Fe I (5576.099 Å) line. The wavelet and Fourier power spectra of the intensity and the velocity at chromospheric levels show both 3 and 5 minute oscillations. Oscillations in the 5 minute band are prominent in the intensity power spectra; they are significantly reduced in the velocity power spectra. We observe multiple peaks of closely spaced cospatial frequencies in the 3 minute band (5-8 mHz). Typically, there are three oscillating modes present: (1) a major one near 5.5 mHz, (2) a secondary near 6.3 mHz, and (3) oscillations with time-varying frequencies around 7.5 mHz that are present for limited time intervals. In the frame of current theories, the oscillating mode near 5.5 mHz should be considered as a fingerprint of the photospheric resonator, while the other two modes can be better explained by the chromospheric resonator. The wavelet spectra show a dynamic temporal behavior of the 3 minute oscillations. We observed (1) frequency drifts, (2) modes that are stable over a long time and then fade away or split up into two oscillation modes, and (3) suppression of frequencies for short time intervals. This behavior can be explained by the coupling between modes closely spaced in frequency or/and by long-term variations of the driving source of the resonators. Based on observations performed on the National Solar Observatory/Sacramento Peak Observatory Richard B. Dunn Solar Telescope (DST) and on the Big Bear Solar Observatory Harold Zirin Telescope.

  7. DETECTING BARYON ACOUSTIC OSCILLATIONS

    SciTech Connect

    Labatie, A.; Starck, J. L.

    2012-02-20

    Baryon acoustic oscillations (BAOs) are a feature imprinted in the galaxy distribution by acoustic waves traveling in the plasma of the early universe. Their detection at the expected scale in large-scale structures strongly supports current cosmological models with a nearly linear evolution from redshift z Almost-Equal-To 1000 and the existence of dark energy. In addition, BAOs provide a standard ruler for studying cosmic expansion. In this paper, we focus on methods for BAO detection using the correlation function measurement {xi}-hat. For each method, we want to understand the tested hypothesis (the hypothesis H{sub 0} to be rejected) and the underlying assumptions. We first present wavelet methods which are mildly model-dependent and mostly sensitive to the BAO feature. Then we turn to fully model-dependent methods. We present the method used most often based on the {chi}{sup 2} statistic, but we find that it has limitations. In general the assumptions of the {chi}{sup 2} method are not verified, and it only gives a rough estimate of the significance. The estimate can become very wrong when considering more realistic hypotheses, where the covariance matrix of {xi}-hat depends on cosmological parameters. Instead, we propose to use the {Delta}l method based on two modifications: we modify the procedure for computing the significance and make it rigorous, and we modify the statistic to obtain better results in the case of varying covariance matrix. We verify with simulations that correct significances are different from the ones obtained using the classical {chi}{sup 2} procedure. We also test a simple example of varying covariance matrix. In this case we find that our modified statistic outperforms the classical {chi}{sup 2} statistic when both significances are correctly computed. Finally, we find that taking into account variations of the covariance matrix can change both BAO detection levels and cosmological parameter constraints.

  8. KY3F10:Er3+/Yb3+ nanocrystals doped laser-induced self-written waveguide for optical amplification in the C-band

    NASA Astrophysics Data System (ADS)

    Xue, Xiaojie; Cheng, Tonglei; Suzuki, Takenobu; Ohishi, Yasutake

    2016-02-01

    We successfully synthesized Er3+/Yb3+ co-doped KY3F10 nanocrystals by a facile hydrothermal method. The average size of the as-prepared nanocrystals was about 60 nm based on the observation of scanning electron microscope. Under the excitation of a 976 nm laser, the Er3+/Yb3+ doped KY3F10 nanocrystals showed intense near-infrared emission band centered at 1539 nm. The optimal concentrations of Er3+ were carefully selected according to the quantum yield measurement for a stronger emission in the C-band. The as-prepared nanocrystals were dispersed into a monomer, bisphenol A ethoxylate diacrylates, in which self-written waveguides can be fabricated under the irradiation of an induced laser at 450 nm. The KY3F10: Er3+/Yb3+ nanocrystals embedded polymer waveguide were fabricated by laser-induced self-written technique. Two pieces of single mode fiber were well connected with the waveguide in the fabrication procedure. Under a 976 nm laser pumping, amplified spontaneous emission at 1539 nm was observed in the KY3F10: Er3+/Yb3+ nanocrystals doped waveguide.

  9. Application of the explicitly correlated coupled-cluster models CCSD(F12*) and CC3(F12*) to the hyperpolarizability of the Ne atom

    SciTech Connect

    Hanauer, Matthias; Köhn, Andreas

    2015-01-22

    This work demonstrates the performance of the recently proposed explicitly correlated coupled-cluster method CCSD(F12*) and a new method using explicitly correlated triple excitations, CC3(F12*), in the calculation of the static ESHG hyperpolarizability of the Ne atom.

  10. CARCINOGENICITY OF CHLOROFORM IN DRINKING WATER TO MALE OSBORNE-MENDEL RATS AND FEMALE B6C3F1 MICE

    EPA Science Inventory

    The carcinogenic activity of chloroform administered at 0, 200, 400, 900, and 1800 mg/liter in drinking water was studied in male Osborne-Mendel rats and female B6C3F1 mice. A second control group was included in the study and was restricted to the water consumption of the high-d...

  11. THE INDUCTION OF HEPATOCELLULAR NEOPLASIA BY TRICHLOROACETIC ACID ADMINISTERED IN THE DRINKING WATER OF THE MALE B6C3F1 MOUSE

    EPA Science Inventory

    Summary What is the study? The study is a chronic bioassay (2 years) of trichloroacetic acid, a drinking water disinfection by-product, in the male B6C3F1 mouse.
    What is the impact to the field and the Agency?
    The impact of this study will derive from the use of...

  12. EVALUATION OF THE IMMUNOMODULATORY EFFECTS OF THE DISINFECTION BYPRODUCT, SODIUM CHLORITE, IN FEMALE B6C3F1 MICE: A DRINKING WATER STUDY

    EPA Science Inventory

    Evaluation of the Immunomodulatory Effects of the Disinfection By-product, Sodium chlorite, in Female B6C3f1 mice: A Drinking Water Study.

    Niel A. Karrow, Tal, L. Guo, J. Ann McCay, Greg W. Johnson, Ronnetta D. Brown, Debrorah L. Musgrove, Dori R. Germolec, Robert W. Lueb...

  13. DIFFERING HEPATOTOXICITY AND LETHALITY AFTER SUBACUTE TRICHLOROETHYLENE EXPOSURE IN AQUEOUS OR CORN OIL GAVAGE VEHICLES IN B6C3F1 MICE

    EPA Science Inventory

    Subacute toxicity of trichloroethylene (TCE) was evaluated in male and female B6C3F1 mice using corn oil or aqueous gavage vehicles. Mice received oral doses of TCE five times a week for 4 weeks at 600, 1200 and 2400 mg/kg/day for males and 450, 900 and 1800 mg/kg/day for females...

  14. IN VITRO PERCUTANEOUS ABSORPTION OF MONOSODIUM METHANERARSONATE (MSMA) AND DISODIUM METHANE-ARSONATE (DSMA) IN FEMALE B6C3F1 MICE

    EPA Science Inventory

    Percutaneous absorption of (14C] monosodium methanearsonate (MSMA) and disodium methanearsonate (DSMA) was investigated in female B6C3F1 mice from a variety of exposure conditions, including aqueous solution, solid compound, and soil. hese chemicals are the sodium salts of methan...

  15. Tunneling Splittings in Vibronic Structure of CH_3F^+ ( X^2E): Studied by High Resolution Photoelectron Spectra and AB Initio Theoretical Method

    NASA Astrophysics Data System (ADS)

    Mo, Yuxiang; Gao, Shuming; Dai, Zuyang; Li, Hua

    2013-06-01

    We report a combined experimental and theoretical study on the vibronic structure of CH_3F^+. The results show that the tunneling splittings of vibrational energy levels occur in CH_3F^+ due to the Jahn-Teller effect. Experimentally, we have measured a high resolution ZEKE spectrum of CH_3F up to 3500 cm^-^1 above the ground state. Theoretically, we performed an ab initio calculation based on the diabatic model. The adiabatic potential energy surfaces (APES) of CH_3F^+ have been calculated at the MRCI/CAS/avq(t)z level and expressed by Taylor expansions with normal coordinates as variables. The energy gradients for the lower and upper APES, the derivative couplings between them and also the energies of the APES have been used to determine the coefficients in the Taylor expansion. The spin-vibronic energy levels have been calculated by accounting all six vibrational modes and their couplings. The experimental ZEKE spectra were assigned based on the theoretical calculations. W. Domcke, D. R. Yarkony, and H. Köpple (Eds.), Conical Intersections: Eletronic Structure, Dynamics and Spectroscopy (World Scientific, Singapore, 2004). M. S. Schuurman, D. E. Weinberg, and D. R. Yarkony, J. Chem. Phys. 127, 104309 (2007).

  16. CARCINOGENICITY OF BROMODICHLOROMETHANE ADMINISTERED IN DRINKING WATER TO MALE F344/N RATS AND B6C3F1 MICE

    EPA Science Inventory

    A life-time exposure study was conducted to assess the carcinogenicity of bromodichloromethane (BDCM) administered in the drinking water to male F344/N rats and B6C3F1 mice. Mouse: Target concentrations of BDCM (dissolved in deionized water containing 0.25% emulphor) were 0.05, ...

  17. Search and Rescue Aircrewman/HH3F Flight Mechanic, 2-10. Military Curriculum Materials for Vocational and Technical Education.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This self-paced, individualized course, adapted from military curriculum materials for use in vocational and technical education, teaches students the skills needed to become a qualified avionics worker on the HH-3F helicopter. The course materials consist of three pamphlets: two student workbooks and a composite ground/flight syllabus. Each…

  18. H3F3A K27M mutation in pediatric CNS tumors: a marker for diffuse high-grade astrocytomas.

    PubMed

    Gielen, Gerrit H; Gessi, Marco; Hammes, Jennifer; Kramm, Christof M; Waha, Andreas; Pietsch, Torsten

    2013-03-01

    Brain tumors are one of the most common childhood malignancies. Diffuse high-grade gliomas represent approximately 10% of pediatric brain tumors. Exon sequencing has identified a mutation in K27M of the histone H3.3 gene (H3F3A K27M and G34R/V) in about 20% of pediatric glioblastomas, but it remains to be seen whether these mutations can be considered specific for pediatric diffuse high-grade astrocytomas or also occur in other pediatric brain tumors. We performed a pyrosequencing-based analysis for the identification of H3F3A codon 27 and codon 34 mutations in 338 pediatric brain tumors. The K27M mutation occurred in 35 of 129 glioblastomas (27.1%) and in 5 of 28 (17.9%) anaplastic astrocytomas. None of the other tumor entities showed H3F3A K27M mutation. Because H3F3A K27M mutations occur exclusively in pediatric diffuse high-grade astrocytomas, analysis of codon 27 mutational status could be useful in the differential diagnosis of these neoplasms. PMID:23429371

  19. Self-organized homo-epitaxial growth in nonlinear optical BaAlBO3F2 crystal crossing lines patterned by laser in glass

    NASA Astrophysics Data System (ADS)

    Shinozaki, K.; Abe, S.; Honma, T.; Komatsu, T.

    2015-11-01

    Crystallization processing of glasses is important as a novel technique for the development of new optical materials, and laser-induced crystallization provides a new challenge in science and technology of materials. Nonlinear optical BaAlBO3F2 crystal lines with crossing, bending, and spiral shapes were patterned at the surface of 2NiO-49BaF2-24.5Al2O3-24.5B2O3 (mol%) and 2.9NiO-48.5BaF2-24.3Al2O3-24.3B2O3 (mol%) glasses by laser irradiation (Yb:YVO4 laser with a wavelength of 1080 nm) and the orientation state of BaAlBO3F2 crystals was examined from birefringence image observations. The birefringence images indicate that the growth of highly c-axis oriented BaAlBO3F2 crystals follows along the laser scanning direction even if the laser scanning direction changes, and in particular the direction of the c-axis of BaAlBO3F2 crystals changes gradually at the crossing and bending points. The model of "self-organized homo-epitaxial growth" is proposed for the crystal orientation at the crossing and bending points, as a new crystal growth science and engineering beyond the wise providence of nature.

  20. Three-step laser excitation of the odd-parity 5s5d 3D → 5s nf 3F states of cadmium

    NASA Astrophysics Data System (ADS)

    Nadeem, Ali; Shah, M.; Haq, S. U.; Shahzada, S.; Mumtaz, M.; Waheed, A.; Nawaz, M.; Ahmed, M.; Baig, M. A.

    2014-07-01

    We report new experimental data on the term energies and effective quantum numbers of the highly excited odd parity states of cadmium in the 71 773-72 500 cm-1 energy range. The experiment was performed using three dye lasers simultaneously pumped by the second harmonic (532 nm) of the Nd;YAG laser. The vapor containment and detection system was a thermionic diode ion detector working in a space charge limited mode. The new observations include the 5snf3F3 (12 ⩽ n ⩽ 52), 5snf3F4 (13 ⩽ n ⩽ 33) and 5snf3F2 (12 ⩽ n ⩽ 22) Rydberg series excited from the 5s5d3D multiplet. A two parameter fit to the transitions energies of the 5snf3F3 series yields the binding energy of the 5snd 2D2 level as 13 042.178 ± 0.02 cm-1 and consequently the first ionization of cadmium is determined as 72 540.05 ± 0.13 cm-1, which is in good agreement with the previously reported value.

  1. EFFECT OF TRICHLOROETHYLENE ON DNA METHYLATION AND EXPRESSION OF EARLY-INTERMEDIATE PROTOONCOGENES IN THE LIVER OF B6C3F1 MICE. (R825384)

    EPA Science Inventory

    Trichloroethylene (TCE) is a multimedia environmental pollution that is carcinogenic in mouse liver. The ability of TCE to modulate DNA methylation and the expression of immediate-early protooncogenes was evaluated. Female B6C3F1 mice were administered 1000 mg/kg TCE by gavage 5 ...

  2. Magnetically Coupled Magnet-Spring Oscillators

    ERIC Educational Resources Information Center

    Donoso, G.; Ladera, C. L.; Martin, P.

    2010-01-01

    A system of two magnets hung from two vertical springs and oscillating in the hollows of a pair of coils connected in series is a new, interesting and useful example of coupled oscillators. The electromagnetically coupled oscillations of these oscillators are experimentally and theoretically studied. Its coupling is electromagnetic instead of…

  3. Global trends and annual releases of CCl3F and CCl2F2 estimated from ALE/GAGE and other measurements from July 1978 to June 1991

    NASA Technical Reports Server (NTRS)

    Cunnold, D. M.; Fraser, P. J.; Weiss, R. F.; Prinn, R. G.; Simmonds, P. G.; Miller, B. R.; Alyea, F. N.; Crawford, A. J.

    1994-01-01

    Thirteen years of Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment CCl3F and CCl2F2 measurements at five remote, surface, globally distributed sites are analyzed. Comparisons are made against shipboard measurements by the Scripps Institution of Oceanography (SIO) group and archived air samples collected at Cape Grim, Tasmania, since 1978. CCl3F in the lower troposphere was increasing at an average rate of 9.2 ppt/yr over the period July 1978 to June 1988. CCl2F2 was increasing at an average 17.3 ppt/yr in the lower troposphere over the same period. However, between July 1988 and June 1991 the increases of CCl3F and CCl2F2 in this region have averaged just 7.0 ppt/yr and 15.7 ppt/yr, respectively. The rate of increase has been decreasing 2.4 ppt/yr(exp 2) and 2.9 ppt/yr(exp 2) over this 3-year period. Based on a recent scenario of the global releases of these compounds and using the new calibration scale SIO 1993, the equilibrium lifetimes are estimated to be 44 +17/-10 and 180 +820/-81 years for CCl3F and CCl2F2, respectively. Using these lifetime estimates and a two-dimensional model, it is estimated that global releases of these two chlorofluorocarbons in 1990 were 249 +/- 28 x 10(exp 6) kg for CCl3F and 366 +/- 30 x 10(exp 6) kg for CCl2F2. It is also estimated that combined releases of these chlorofluorocarbons in 1990 were 21 +/- 5% less than those in 1986.

  4. Enhancement of the luminescent properties of a new red-emitting phosphor, Mn2(HPO3)F2, by Zn substitution.

    PubMed

    Orive, Joseba; Mesa, José L; Balda, Rolindes; Fernández, Joaquín; Fernández, Jesús Rodríguez; Rojo, Teófilo; Arriortua, María I

    2011-12-19

    The Mn(2)(HPO(3))F(2) phase has been synthesized as single crystals by using mild hydrothermal conditions. The compound crystallizes in the orthorhombic Pnma space group, with unit cell parameters of a = 7.5607(8), b = 10.2342(7), and c = 5.5156(4) Å, with Z = 4. The crystal structure consists of a three-dimensional framework formed by alternating (010) layers of [MnO(3)F(3)] octahedra linked up by three connected [HPO(3)] tetrahedra. Luminescence measurements were performed at different temperatures between 10 and 150 K. The 10 K emission spectrum of the octahedrally coordinated Mn(II) cation exhibits a broad band centered at around 615 nm corresponding to the (4)T(1) → (6)A(1) transition. In order to explore the effect of the Mn(II) concentration and the possibility of enhancing the luminescence properties of the Mn(II) cation in Mn(2)(HPO(3))F(2), different intermediate composition members of the finite solid solution with the general formula (Mn(x)Zn(1-x))(2)(HPO(3))F(2) were prepared and their luminescent properties studied. The magnetic and specific heat behavior of M(2)(HPO(3))F(2) (M = Mn, Fe) have also been investigated. The compounds exhibit a global antiferromagnetic ordering with a spin canting phenomenon detected at approximately 30 K. The specific heat measurements show sharp λ-type peaks at 29.7 and 33.5 K for manganese and iron compounds, respectively. The total magnetic entropy is consistent with spin S = 5/2 and S = 2 of Mn(II) and Fe(II) cations. PMID:22085224

  5. Crystal structure and luminescence properties of a novel red-emitting phosphor BaAlBO{sub 3}F{sub 2}:Eu{sup 3+}

    SciTech Connect

    Chen, Wanping Zhou, Ahong; Liu, Yan; Dai, Xiaoyan; Yang, Xin

    2014-12-15

    A series of novel red-emitting phosphors BaAlBO{sub 3}F{sub 2}:xEu{sup 3+} (0.001≤x≤0.08) were first synthesized via a high temperature solid-state reaction. X-ray diffraction and photoluminescence spectroscopy were used to characterize the crystal structure and photoluminescence properties of the phosphor, respectively. The phosphor can be effectively excited with a 395 nm light, and shows a dominant {sup 5}D{sub 0}−{sup 7}F{sub 2} emission with chromatic coordination of 0.628 and 0.372. The optimal doping concentration is about 0.04. Rietveld refinement results and the luminescence behavior of Eu{sup 3+} indicate that the Eu{sup 3+} ion occupies a C{sub 3} symmetry site, and the host BaAlBO{sub 3}F{sub 2} has a hexagonal structure with P-6 space group. In addition, the phosphor could be a potential candidate as red-emitting phosphor for application in white light-emitting diode. - Graphical abstract: The luminescence behavior and Rietveld refinement of BaAlBO{sub 3}F{sub 2}:Eu{sup 3+} indicate that the red-emitting phosphor has potential application in white LED and the host has a hexagonal structure with P-6 space group. - Highlights: • A novel red-emitting phosphor BaAlBO{sub 3}F{sub 2}:Eu{sup 3+} is first synthesized. • The crystal structure of BaAlBO{sub 3}F{sub 2} is confirmed. • The phosphor shows potential application in white LED.

  6. Carcinogenicity of acrylamide in B6C3F(1) mice and F344/N rats from a 2-year drinking water exposure.

    PubMed

    Beland, Frederick A; Mellick, Paul W; Olson, Greg R; Mendoza, Maria C B; Marques, M Matilde; Doerge, Daniel R

    2013-01-01

    Acrylamide is a component of roasted coffee and certain baked and fried carbohydrate-rich foods prepared at high temperatures. We have assessed the carcinogenicity of acrylamide in male and female B6C3F(1) mice and F344/N rats administered 0, 0.0875, 0.175, 0.35, or 0.70mM acrylamide in the drinking water ad libitum for 2 years. Acrylamide caused significant dose-related decreasing trends in the body weights of F344/N rats. Acrylamide administration resulted in significant dose-related decreasing trends in survival in both sexes of B6C3F(1) mice and in female F344/N rats. Histopathological analyses indicated significant dose-related increases in Harderian gland and lung tumors in male and female B6C3F(1) mice. Male B6C3F(1) mice also had a significantly increased incidence of forestomach tumors, while female B6C3F(1) mice had significant dose-related increases in mammary gland, ovary, and skin tumors. In male and female F344/N rats, there were significant increases in thyroid tumors. Male F344/N rats also had significant dose-related increases in testes, heart, and pancreas tumors, while female F344 rats demonstrated significant increases in clitoral gland, mammary gland, oral cavity, and skin tumors. These results, combined with previous mechanistic studies, provide strong support for the concept that acrylamide is activated to a carcinogen through metabolism to glycidamide. PMID:23009883

  7. Nonlinear oscillations of coalescing magnetic flux ropes.

    PubMed

    Kolotkov, Dmitrii Y; Nakariakov, Valery M; Rowlands, George

    2016-05-01

    An analytical model of highly nonlinear oscillations occurring during a coalescence of two magnetic flux ropes, based upon two-fluid hydrodynamics, is developed. The model accounts for the effect of electric charge separation, and describes perpendicular oscillations of the current sheet formed by the coalescence. The oscillation period is determined by the current sheet thickness, the plasma parameter β, and the oscillation amplitude. The oscillation periods are typically greater or about the ion plasma oscillation period. In the nonlinear regime, the oscillations of the ion and electron concentrations have a shape of a narrow symmetric spikes. PMID:27300993

  8. Structure dependence of oscillation characteristics of resonant-tunneling-diode terahertz oscillators associated with intrinsic and extrinsic delay times

    NASA Astrophysics Data System (ADS)

    Kanaya, Hidetoshi; Maekawa, Takeru; Suzuki, Safumi; Asada, Masahiro

    2015-09-01

    We investigate the effect of intrinsic and extrinsic delay times on the oscillation characteristics of resonant-tunneling-diode (RTD) terahertz oscillators. The intrinsic delay time is composed of the electron dwell time in the resonant tunneling region and the electron transit time in the collector depletion region. We obtain and discuss the structure dependence of these factors in terms of the oscillation frequency and output power measured for RTD oscillators with different quantum-well and collector-spacer thicknesses and different air-bridge widths between the RTD and a slot antenna. The highest oscillation frequency achieved in this experiment is 1.86 THz for the well and spacer thicknesses of 2.5 and 12 nm, respectively, with a 1-µm-wide air bridge. In this structure, the extrinsic delay time (80 fs) estimated from the parasitic elements is more than double the intrinsic delay time (35 fs). It is shown theoretically that an oscillation frequency of over 2 THz is possible upon the reduction in the extrinsic delay time caused by the bulk and spread resistances in RTDs.

  9. Isolation, spectroscopic and density functional theory studies of 7-(4-methoxyphenyl)-9H-furo[2,3-f]chromen-9-one: A new flavonoid from the bark of Millettia ovalifolia

    NASA Astrophysics Data System (ADS)

    Rahman, Taj Ur; Arfan, Mohammad; Mahmood, Tariq; Liaqat, Wajiha; Gilani, Mazhar Amjad; Uddin, Ghias; Ludwig, Ralf; Zaman, Khair; Choudhary, M. Iqbal; Khattak, Khanzadi Fatima; Ayub, Khurshid

    2015-07-01

    The phytochemical examination of chloroform soluble fraction (FX2) of methanolic extract of bark of Millettia ovalifolia yielded a new flavonoid; 7-(4-methoxyphenyl)-9H-furo [2,3-f]chromen-9-one (1). Compound 1 is characterized by spectroscopic analytical techniques such as UV, IR, 1D, 2D NMR spectroscopy, and mass spectrometry. A theoretical model is also developed for obtaining geometric, electronic and spectroscopic properties of 1. The geometry optimization and harmonic vibration simulations have been carried out at B3LYP/6-31G(d,p). The vibrational spectrum of compound 1 shows nice correlation with the experimental IR spectrum, through a scaling factor of 0.9613. 1H and 13C NMR chemical shifts are simulated using Cramer's re-parameterized function WP04 at 6-31G(d,p) basis set, and correlate nicely with the experimental chemical shifts.

  10. The source of solar oscillations

    NASA Astrophysics Data System (ADS)

    Nigam, R.

    1999-05-01

    In this study the role of line asymmetry and phase difference between velocity and intensity helioseismic spectra for understanding the excitation of solar oscillations is discussed. The solar intensity and velocity oscillations are usually observed from variations in an absorption line. These variations consist of two parts: solar oscillation modes and granulation noise. Because the oscillation modes are excited by granulation, we argue that the granulation signal (noise) is partially correlated with the oscillations. The data from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO) have clearly revealed a reversal of asymmetry between velocity and intensity power spectra. We have shown that the cause of reversal in asymmetry between velocity and intensity power spectra is due to the presence of the correlated noise in the intensity data. This noise is also responsible for the high-frequency shift in the two spectra at and above the acoustic cutoff frequency. Our theory also explains the deviation of the observed phase difference between velocity and intensity from that predicted by simple adiabatic theory of solar oscillations. The observed phase, jumps in the vicinity of an eigenfrequency, but theory does not explain such jumps. We studied different types of excitation sources at various depths and found that monopole and quadrupole acoustic sources when placed in the superadiabatic layer (at a depth of 75 km below the photosphere) match the observations. For these source types, the sign of the correlation is negative corresponding to photospheric darkening. Finally, an asymmetric fitting formula is used to determine the eigenfrequencies of solar oscillations by fitting both the velocity and intensity power spectra.

  11. The Source of Solar Oscillations

    NASA Astrophysics Data System (ADS)

    Nigam, R.; Kosovichev, A. G.

    1998-12-01

    In this study the role of line asymmetry and phase difference between velocity and intensity helioseismic spectra for understanding the excitation of solar oscillations is discussed. The solar intensity and velocity oscillations are usually observed from variations in an absorption line. These variations consist of two parts: solar oscillation modes and granulation noise. Because the oscillation modes are excited by granulation, we argue that the granulation signal (noise) is partially correlated with the oscillations. The data from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO) have clearly revealed a reversal of asymmetry between velocity and intensity power spectra. We have shown that the cause of reversal in asymmetry between velocity and intensity power spectra is due to the presence of the correlated noise in the intensity data. This noise is also responsible for the high-frequency shift in the two spectra at and above the acoustic cutoff frequency. Our theory also explains the deviation of the observed phase difference between velocity and intensity from that predicted by simple adiabatic theory of solar oscillations. The observed phase, jumps in the vicinity of an eigenfrequency, but theory does not explain such jumps. We studied different types of excitation sources at various depths and found that monopole and quadrupole acoustic sources when placed in the superadiabatic layer (at a depth of 75 km below the photosphere) match the observations. For these source types, the sign of the correlation is negative corresponding to photospheric darkening. Finally, an asymmetric fitting formula is used to determine the eigenfrequencies of solar oscillations by fitting both the velocity and intensity power spectra.

  12. Simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament induced by a single shock wave

    SciTech Connect

    Shen, Yuandeng; Liu, Ying D.; Chen, P. F.; Ichimoto, Kiyoshi

    2014-11-10

    We present the first stereoscopic and Doppler observations of simultaneous transverse oscillations of a prominence and a filament and longitudinal oscillation of another filament launched by a single shock wave. Using Hα Doppler observations, we derive the three-dimensional oscillation velocities at different heights along the prominence axis. The results indicate that the prominence has a larger oscillation amplitude and damping time at higher altitude, but the periods at different heights are the same (i.e., 13.5 minutes). This suggests that the prominence oscillates like a linear vertical rigid body with one end anchored on the Sun. One of the filaments shows weak transverse oscillation after the passing of the shock, which is possibly due to the low altitude of the filament and the weakening (due to reflection) of the shock wave before the interaction. Large-amplitude longitudinal oscillation is observed in the other filament after the passing of the shock wave. The velocity amplitude and period are about 26.8 km s{sup –1} and 80.3 minutes, respectively. We propose that the orientation of a filament or prominence relative to the normal vector of the incoming shock should be an important factor for launching transverse or longitudinal filament oscillations. In addition, the restoring forces of the transverse prominence are most likely due to the coupling of gravity and magnetic tension of the supporting magnetic field, while that for the longitudinal filament oscillation is probably the resultant force of gravity and magnetic pressure.

  13. Surface tension and viscosity from damped free oscillations of viscous droplets

    NASA Technical Reports Server (NTRS)

    Suryanarayana, P. V. R.; Bayazitoglu, Yildiz

    1990-01-01

    Damped oscillations of a viscous droplet in vacuum or in an inert gas of negligible density are considered. The dependence of the complex decay factor on the properties of the liquid is investigated for the first time, and numerical results are compared with earlier studies for special cases. A new method is developed to determine both surface tension and viscosity from a single experiment in which the damping rate and frequency of oscillations are measured. The procedure to determine surface tension and viscosity from oscillating levitated liquids is outlined, and results presented for various modes of shape oscillations.

  14. Relative Potency for Altered Humoral Immunity Induced by Polybrominated and Polychlorinated Dioxins/Furans in Female B6C3F1/N Mice

    PubMed Central

    Frawley, Rachel; DeVito, Michael; Walker, Nigel J.; Birnbaum, Linda; White, Kimber; Smith, Matthew; Maynor, Timothy; Recio, Leslie; Germolec, Dori

    2014-01-01

    The use of brominated flame retardants and incineration of bromine-containing materials has lead to an increase in polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in the environment. Measurable amounts of PBDD/Fs have been detected in soil, seafood, and human breast milk and serum. Studies indicate that the relative potencies of some PBDD/Fs based on enzyme induction are equivalent to those of some polychlorinated dibenzo-p-dioxins and dibenzofurans. To assess the humoral immunity relative potencies of PBDD/Fs and compare them to their chlorinated analogs, female B6C3F1/N mice received a single oral exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrabromodibenzofuran (TBDF), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 1,2,3,7,8-pentabromodibenzofuran (1PeBDF), 1,2,3,7,8-pentachlorodibenzofuran (1PeCDF), 2,3,4,7,8-pentabromodibenzofuran (4PeBDF), 2,3,4,7,8-pentachlorodibenzofuran (4PeCDF), 2,3-dibromo-7,8-dichlorodibenzo-p-dioxin (DBDCDD), or 2,3,7-tribromodibenzo-p-dioxin (TriBDD). Inhibition of the immunoglobulin M (IgM) antibody forming cell response was measured 4 days following immunization with sheep red blood cells. The data were fit to a Hill model to estimate the ED50 for inhibition. Expression of xenobiotic metabolizing enzyme (XME) and thyroxine transport protein (Ttr) genes in liver was measured by PCR to assess aryl hydrocarbon-mediated responses. TCDD, TBDF, TCDF, 1PeBDF, 4PeBDF, 4PeCDF, and DBDCDD suppressed the IgM antibody response and Ttr gene expression, and upregulated phase I XME genes. 1PeCDF suppressed the IgM antibody response but only upregulated phase I XME genes; TriBDD had no effect on antibody response. The rank order of potency (ED50) for these chemicals was TCDD>TBDF>4PeBDF>TCDF/4PeCDF/1PeBDF>1PeCDF. Whereas TCDD was the most potent compound tested, the brominated analogs were more potent than their chlorinated analogs, suggesting that these compounds should be considered in toxic equivalency factor

  15. Arrays of coupled chemical oscillators

    PubMed Central

    Forrester, Derek Michael

    2015-01-01

    Oscillating chemical reactions result from complex periodic changes in the concentration of the reactants. In spatially ordered ensembles of candle flame oscillators the fluctuations in the ratio of oxygen atoms with respect to that of carbon, hydrogen and nitrogen produces an oscillation in the visible part of the flame related to the energy released per unit mass of oxygen. Thus, the products of the reaction vary in concentration as a function of time, giving rise to an oscillation in the amount of soot and radiative emission. Synchronisation of interacting dynamical sub-systems occurs as arrays of flames that act as master and slave oscillators, with groups of candles numbering greater than two, creating a synchronised motion in three-dimensions. In a ring of candles the visible parts of each flame move together, up and down and back and forth, in a manner that appears like a “worship”. Here this effect is shown for rings of flames which collectively empower a central flame to pulse to greater heights. In contrast, situations where the central flames are suppressed are also found. The phenomena leads to in-phase synchronised states emerging between periods of anti-phase synchronisation for arrays with different columnar sizes of candle and positioning. PMID:26582365

  16. Arrays of coupled chemical oscillators.

    PubMed

    Forrester, Derek Michael

    2015-01-01

    Oscillating chemical reactions result from complex periodic changes in the concentration of the reactants. In spatially ordered ensembles of candle flame oscillators the fluctuations in the ratio of oxygen atoms with respect to that of carbon, hydrogen and nitrogen produces an oscillation in the visible part of the flame related to the energy released per unit mass of oxygen. Thus, the products of the reaction vary in concentration as a function of time, giving rise to an oscillation in the amount of soot and radiative emission. Synchronisation of interacting dynamical sub-systems occurs as arrays of flames that act as master and slave oscillators, with groups of candles numbering greater than two, creating a synchronised motion in three-dimensions. In a ring of candles the visible parts of each flame move together, up and down and back and forth, in a manner that appears like a "worship". Here this effect is shown for rings of flames which collectively empower a central flame to pulse to greater heights. In contrast, situations where the central flames are suppressed are also found. The phenomena leads to in-phase synchronised states emerging between periods of anti-phase synchronisation for arrays with different columnar sizes of candle and positioning. PMID:26582365

  17. Arrays of coupled chemical oscillators

    NASA Astrophysics Data System (ADS)

    Forrester, Derek Michael

    2015-11-01

    Oscillating chemical reactions result from complex periodic changes in the concentration of the reactants. In spatially ordered ensembles of candle flame oscillators the fluctuations in the ratio of oxygen atoms with respect to that of carbon, hydrogen and nitrogen produces an oscillation in the visible part of the flame related to the energy released per unit mass of oxygen. Thus, the products of the reaction vary in concentration as a function of time, giving rise to an oscillation in the amount of soot and radiative emission. Synchronisation of interacting dynamical sub-systems occurs as arrays of flames that act as master and slave oscillators, with groups of candles numbering greater than two, creating a synchronised motion in three-dimensions. In a ring of candles the visible parts of each flame move together, up and down and back and forth, in a manner that appears like a “worship”. Here this effect is shown for rings of flames which collectively empower a central flame to pulse to greater heights. In contrast, situations where the central flames are suppressed are also found. The phenomena leads to in-phase synchronised states emerging between periods of anti-phase synchronisation for arrays with different columnar sizes of candle and positioning.

  18. Synthetic in vitro transcriptional oscillators.

    PubMed

    Kim, Jongmin; Winfree, Erik

    2011-02-01

    The construction of synthetic biochemical circuits from simple components illuminates how complex behaviors can arise in chemistry and builds a foundation for future biological technologies. A simplified analog of genetic regulatory networks, in vitro transcriptional circuits, provides a modular platform for the systematic construction of arbitrary circuits and requires only two essential enzymes, bacteriophage T7 RNA polymerase and Escherichia coli ribonuclease H, to produce and degrade RNA signals. In this study, we design and experimentally demonstrate three transcriptional oscillators in vitro. First, a negative feedback oscillator comprising two switches, regulated by excitatory and inhibitory RNA signals, showed up to five complete cycles. To demonstrate modularity and to explore the design space further, a positive-feedback loop was added that modulates and extends the oscillatory regime. Finally, a three-switch ring oscillator was constructed and analyzed. Mathematical modeling guided the design process, identified experimental conditions likely to yield oscillations, and explained the system's robust response to interference by short degradation products. Synthetic transcriptional oscillators could prove valuable for systematic exploration of biochemical circuit design principles and for controlling nanoscale devices and orchestrating processes within artificial cells. PMID:21283141

  19. Large amplitude drop shape oscillations

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Wang, T. G.

    1982-01-01

    An experimental study of large amplitude drop shape oscillation was conducted in immiscible liquids systems and with levitated free liquid drops in air. In liquid-liquid systems the results indicate the existence of familiar characteristics of nonlinear phenomena. The resonance frequency of the fundamental quadrupole mode of stationary, low viscosity Silicone oil drops acoustically levitated in water falls to noticeably low values as the amplitude of oscillation is increased. A typical, experimentally determined relative frequency decrease of a 0.5 cubic centimeters drop would be about 10% when the maximum deformed shape is characterized by a major to minor axial ratio of 1.9. On the other hand, no change in the fundamental mode frequency could be detected for 1 mm drops levitated in air. The experimental data for the decay constant of the quadrupole mode of drops immersed in a liquid host indicate a slight increase for larger oscillation amplitudes. A qualitative investigation of the internal fluid flows for such drops revealed the existence of steady internal circulation within drops oscillating in the fundamental and higher modes. The flow field configuration in the outer host liquid is also significantly altered when the drop oscillation amplitude becomes large.

  20. Oscillator strengths for a Li I 207-A laser.

    PubMed

    Nussbaumer, H

    1980-06-01

    Atomic data crucial for a proposed 207-A lithium laser have been calculated in a multiconfiguration approximation. The values obtained for the intercombination oscillator strengths ls2s2p 4 P(o)-1s2p2 2P are approximately a factor of 15 smaller than those assumed in the proposal of Harris [Opt. Lett. 5,1 (1980)]. PMID:19693180

  1. Effect of the [Ba2BO3F]∞ Layer on the Band Gap: Synthesis, Characterization, and Theoretical Studies of BaZn2B2O6·nBa2BO3F (n = 0, 1, 2).

    PubMed

    Wu, Hongping; Su, Xin; Han, Shujuan; Yang, Zhihua; Pan, Shilie

    2016-05-16

    Two new zincoborate fluorides with the common formula BaZn2B2O6·nBa2BO3F (n = 1, 2) have been successfully synthesized for the relationship study between the band gaps and crystal structures in zinc-containing borate fluorides. Ba3Zn2B3O9F with n = 1 in the common formula belongs to the orthorhombic space group Pnma (No. 20), and Ba5Zn2B4O12F2 with n = 2 in the common formula crystallizes in the monoclinic space group C2/c (No. 62). They can both be seen as compounds with the n[Ba2BO3F]∞ (n = 1 or 2) layer inserted in the structure of BaZn2B2O6. UV-vis-near-IR diffuse-reflectance spectra show that the band gaps of BaZn2B2O6·nBa2BO3F (n = 0, 1, 2) gradually increase with more [Ba2BO3F]∞ layers inserted. The first-principles calculation indicates that the inserted n[Ba2BO3F]∞ layers play a positive effect in increasing the band gaps of zincoborate fluorides. Furthermore, the IR spectra, thermal behaviors, and refractive indices of these compounds are also studied. PMID:27119618

  2. TOXICITY AND CARCINOGENICITY STUDIES OF 4-METHYLIMIDAZOLE IN F344/N RATS AND B6C3F1 MICE

    PubMed Central

    Chan, P.C.; Hills, G. D; Kissling, G.E.; Nyska, A

    2008-01-01

    4-Methylimidazole (4MI) is used in the manufacture of pharmaceuticals, photographic chemicals, dyes and pigments, cleaning and agricultural chemicals, and rubber. It has been identified as a by-product of fermentation in foods and has been detected in mainstream and side stream tobacco smoke. 4MI was studied because of its high potential for human exposure. Groups of 50 male and 50 female F344/N rats were fed diets containing 0-, 625-, 1,250-, or 2,500-ppm 4MI (males) or 0-, 1,250-, 2,500-, or 5,000-ppm 4MI (females) for 106 weeks. Based on the food consumption the calculated average daily doses were approximately 30, 55, or 115 mg 4MI/kg body weight to males and 60, 120, or 250 mg 4MI/kg to females. Survival of all exposed groups of males and females was similar to that of the control groups. Mean body weights of males in the 1,250- and 2,500-ppm groups and females in the 2,500- and 5,000-ppm groups were less than those of the control groups throughout the study. Feed consumption by 5,000-ppm females was less than that by the controls. Clonic seizures, excitability, hyperactivity, and impaired gait were observed primarily in 2,500- and 5,000-ppm females. The incidence of mononuclear cell leukemia in the 5,000-ppm females was significantly greater than that in the controls. The incidences of hepatic histiocytosis, chronic inflammation, and focal fatty change were significantly increased in all exposed groups of male and female rats. The incidences of hepatocellular eosinophilic and mixed cell foci were significantly increased in 2,500-ppm males and 5,000-ppm females. Groups of 50 male and 50 female B6C3F1 mice were fed diets containing 0-, 312-, 625-, or 1,250-ppm 4MI for 106 weeks. Based on the food consumption the calculated average daily doses were approximately 40, 80, or 170 mg 4MI/kg body weight to males and females. Survival of all exposed groups of males and females was similar to that of the control groups. Mean body weights of males and females in the 1

  3. [Low-Frequency Flow Oscillation

    NASA Technical Reports Server (NTRS)

    Bragg, Michael B.

    1997-01-01

    The results of the research conducted under this grant are presented in detail in three Master theses, by Heinrich, Balow, and Broeren. Additional analysis of the experimental data can be found in two AIAA Journal articles and two conference papers. Citations for all of the studies' publications can be found in the bibliography which is attached. The objective of Heinrich's study was to document the low-frequency flow oscillation on the LRN-1007 airfoil, which had been previously observed at low Reynolds number, to determine its origin, and explore the phenomenon at higher Reynolds number. Heinrich performed detailed flow visualization on the airfoil using surface fluorescent oil and laser-sheet off-body visualization. A large leading-edge separation bubble and trailing-edge separation was identified on the airfoil just prior to the onset of the unsteady stall flow oscillation. From the laser-sheet data, the unsteady flow appeared as a massive boundary-layer separation followed by flow reattachment. Hot-wire data were taken in the wake to identify the presence of the flow oscillation and the dominant frequency. The oscillation was found in the flow from a Reynolds number of 0.3 to 1.3 x 10 exp 6. The Strouhal number based on airfoil projected height was nominally 0.02 and increased slightly with increasing Reynolds number and significantly with increasing airfoil angle of attack. Balow focused his research on the leading-edge separation bubble which was hypothesized to be the origin of the low-frequency oscillation. Initially, experimental measurements in the bubble at the onset of the low-frequency oscillation were attempted to study the characteristics of the bubble and explain possible relationships to the shear-layer-flapping phenomena. Unfortunately, the bubble proved to be extremely sensitive to the probe interference and it drastically reduced the size of the bubble. These detailed measurements were then abandoned by Balow. However, this led to a series of

  4. Oscillations of solar atmosphere neutrinos

    SciTech Connect

    Fogli, G. L.; Lisi, E.; Mirizzi, A.; Montanino, D.; Serpico, P. D.

    2006-11-01

    The Sun is a source of high-energy neutrinos (E(greater-or-similar sign)10 GeV) produced by cosmic ray interactions in the solar atmosphere. We study the impact of three-flavor oscillations (in vacuum and in matter) on solar atmosphere neutrinos, and calculate their observable fluxes at Earth, as well as their event rates in a kilometer-scale detector in water or ice. We find that peculiar three-flavor oscillation effects in matter, which can occur in the energy range probed by solar atmosphere neutrinos, are significantly suppressed by averaging over the production region and over the neutrino and antineutrino components. In particular, we find that the relation between the neutrino fluxes at the Sun and at the Earth can be approximately expressed in terms of phase-averaged vacuum oscillations, dominated by a single mixing parameter (the angle {theta}{sub 23})

  5. Nonstationary oscillations in gyrotrons revisited

    SciTech Connect

    Dumbrajs, O.; Kalis, H.

    2015-05-15

    Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. It is known that in the planes of the generalized gyrotron variables: cyclotron resonance mismatch and dimensionless current or cyclotron resonance mismatch and dimensionless interaction length complicated alternating sequences of regions of stationary, periodic, automodulation, and chaotic oscillations exist. In the past, these regions were investigated on the supposition that the transit time of electrons through the interaction space is much shorter than the cavity decay time. This assumption is valid for short and/or high diffraction quality resonators. However, in the case of long and/or low diffraction quality resonators, which are often utilized, this assumption is no longer valid. In such a case, a different mathematical formalism has to be used for studying nonstationary oscillations. One example of such a formalism is described in the present paper.

  6. Magnetically insulated transmission line oscillator

    DOEpatents

    Bacon, L.D.; Ballard, W.P.; Clark, M.C.; Marder, B.M.

    1987-05-19

    A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields are produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap. 11 figs.

  7. Magnetically insulated transmission line oscillator

    DOEpatents

    Bacon, Larry D.; Ballard, William P.; Clark, M. Collins; Marder, Barry M.

    1988-01-01

    A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields arfe produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap.

  8. High power radial klystron oscillator

    SciTech Connect

    Arman, M.J.

    1995-11-01

    The advantages of the radial klystron amplifier over the conventional klystron amplifier have been reported by Arman et al. Briefly, the radial structure of this design allows for much smaller impedances and thus higher power, the beam-cavity coupling is stronger because the beam travels inside the cavity, and the source is much more compact because there is no need for external magnetic fields. Here the author reports on possible advantages of the radial klystron oscillator over the radial klystron amplifier. The amplifying nature of certain HPM sources is often mandated by the requirement for synchronization and phase-locking of a number of sources in specific applications. In situations where amplification is solely adhered to for the purpose of achieving higher powers, the oscillator will be a better choice if a mechanism can be found to grow the desired mode at the required frequency. By switching to the oscillator mode there will be no need for priming the cavity or maintaining the phase. This simplifies the design and reduces the operational and maintenance cost of the source. Here he reports that an oscillator version of the radial klystron is possible and in fact more suitable for many applications. The mechanism for exciting and growing the mode will be transit-time effects thus providing all the beneficial features of the transit-time oscillators. The complications due to the presence of thin foils in the radial design still persist and will be dealt with in subsequent works. Numerical simulations using the PIC codes MAGIC and SOS indicate the radial klystron oscillator is a viable and efficient means of rf generation.

  9. Smart contact oscillations by IPMCs

    NASA Astrophysics Data System (ADS)

    Asanuma, H.; Asaka, K.; Su, J.; Poubel, L.; Shahinpoor, M.

    2016-02-01

    An ion migration-induced self-oscillation phenomenon observed in ionic polymer metal composites (IPMCs) is reported. These oscillations are generated from a purely static equilibrium configuration of IPMCs in loose contact with a stationary electrode, and in particular the anode of an imposed DC voltage source. Many interesting possibilities emerge, which are described in this paper. Of particular importance is the emergence of the possibility of creating tailor-made electric signals or pulse-width modulation-type signals from a DC source.

  10. Cherenkov radiation oscillator without reflectors

    SciTech Connect

    Li, D.; Wang, Y.; Wei, Y.; Yang, Z.; Hangyo, M.; Miyamoto, S.

    2014-05-12

    This Letter presents a Cherenkov radiation oscillator with an electron beam travelling over a finitely thick plate made of negative-index materials. In such a scheme, the external reflectors required in the traditional Cherenkov oscillators are not necessary, since the electromagnetic energy flows backward in the negative-index materials, leading to inherent feedback. We theoretically analyzed the interaction between the electron beam and the electromagnetic wave, and worked out the growth rate and start current through numerical calculations. With the help of particle-in-cell simulation, the theoretical predictions are well demonstrated.

  11. Free oscillations of magnetic fluid in strong magnetic field

    NASA Astrophysics Data System (ADS)

    Polunin, V. M.; Ryapolov, P. A.; Platonov, V. B.; Kuz'ko, A. E.

    2016-05-01

    The paper presents the esults of measuring the elastic parameters of an oscillatory system (coefficient of pondermotive elasticity, damping factor, and oscillation frequency) whose viscous inertial element is represented by a magnetic fluid confined in a tube by magnetic levitation in a strong magnetic field. The role of elasticity is played by the pondermotive force acting on thin layers at the upper and lower ends of the fluid column. It is shown that, by measuring the elastic oscillation frequencies of the magnetic fluid column, it is possible to develop a fundamentally new absolute method for determining the saturation magnetization of a magnetic colloid.

  12. Mixed-mode oscillation suppression states in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Ghosh, Debarati; Banerjee, Tanmoy

    2015-11-01

    We report a collective dynamical state, namely the mixed-mode oscillation suppression state where the steady states of the state variables of a system of coupled oscillators show heterogeneous behaviors. We identify two variants of it: The first one is a mixed-mode death (MMD) state, which is an interesting oscillation death state, where a set of variables show dissimilar values, while the rest arrive at a common value. In the second mixed death state, bistable and monostable nontrivial homogeneous steady states appear simultaneously to a different set of variables (we refer to it as the MNAD state). We find these states in the paradigmatic chaotic Lorenz system and Lorenz-like system under generic coupling schemes. We identify that while the reflection symmetry breaking is responsible for the MNAD state, the breaking of both the reflection and translational symmetries result in the MMD state. Using a rigorous bifurcation analysis we establish the occurrence of the MMD and MNAD states, and map their transition routes in parameter space. Moreover, we report experimental observation of the MMD and MNAD states that supports our theoretical results. We believe that this study will broaden our understanding of oscillation suppression states; subsequently, it may have applications in many real physical systems, such as laser and geomagnetic systems, whose mathematical models mimic the Lorenz system.

  13. Anti-GD2 antibody 3F8 and barley-derived (1 → 3),(1 → 4)-β-D-glucan

    PubMed Central

    Modak, Shakeel; Kushner, Brian H.; Kramer, Kim; Vickers, Andrew; Cheung, Irene Y.; Cheung, Nai-Kong V.

    2013-01-01

    β-glucans are complex, naturally-occurring polysaccharides that prime leukocyte dectin and complement receptor 3. Based on our preclinical findings, indicating that oral barley-derived (1 → 3),(1 → 4)-β-D-glucan (BG) synergizes with the murine anti-GD2 antibody 3F8 against neuroblastoma, we conducted a Phase I clinical study to evaluate the safety of this combinatorial regimen in patients affected by chemoresistant neuroblastoma. In this setting, four cohorts of six heavily pre-treated patients bearing recurrent or refractory advanced-stage neuroblastoma were treated with 3F8 plus BG. Each cycle consisted of intravenous 3F8 at a fixed dose of 10 mg/m2/day plus concurrent oral BG, dose-escalated from 10 to 80 mg/Kg/day, for 10 d. Patients who did not develop human anti-mouse antibodies could be treated for up to 4 cycles. Twenty-four patients completed 50 cycles of therapy. All patients completed at least one cycle and were evaluable for the assessment of toxicity and responses. The maximum tolerated dose of BG was not reached, but two patients developed dose-limiting toxicities. These individuals developed grade 4 thrombocytopenia after one cycle of BG at doses of 20 mg/Kg/day and 40 mg/Kg/day, respectively. Platelet counts recovered following the administration of idiopathic thrombocytopenic purpura therapy. There were no other toxicities of grade > 2. Eleven and 13 patients manifested stable and progressive disease, respectively. Thirteen out of 22 patients with pre-treatment positive 123I-MIBG scans demonstrated clinical improvement on semiquantitative scoring. Responses did not correlate with BG dose or with in vitro cytotoxicity. In summary, 3F8 plus BG is well tolerated and shows antineoplastic activity in recurrent or refractory advanced-stage neuroblastoma patients. Further clinical investigation of this novel combinatorial immunotherapeutic regimen is warranted. PMID:23802080

  14. DICHLOROACETATE TOXICOKINETICS AND DISRUPTION OF TYROSINE CATABOLISM IN B6C3F1 MICE: DOSE RESPONSE RELATIONSHIPS AND AGE AS A MODIFYING FACTOR. (R825954)

    EPA Science Inventory

    Dichloroacetate (DCA) is a rodent carcinogen commonly found in municipal drinking water supplies. Toxicokinetic studies have established that elimination of DCA is controlled by liver metabolism, which occurs by the cytosolic enzyme glutathione-S-transferase-zeta (GST-z...

  15. Empirical formula of crustal torsional oscillations

    NASA Astrophysics Data System (ADS)

    Sotani, Hajime

    2016-02-01

    Crustal torsional oscillations depend on not only crust properties but also the stellar mass and radius. Thus, one could extract stellar information by identifying the observed frequencies of stellar oscillations with the crustal torsional oscillations. Owing to the confinement of torsional oscillations inside the crust region of neutron stars, we successfully derive an empirical formula for the fundamental crustal torsional oscillations as a function of the stellar mass, radius, the so-called slope parameter of the nuclear symmetry energy, and the angular index of oscillations, with which one can estimate the frequencies with high accuracy. This empirical formula could be valuable in both the astrophysics and nuclear physics communities.

  16. Calculations of combustion response profiles and oscillations

    NASA Technical Reports Server (NTRS)

    Priem, Richard J.; Breisacher, Kevin J.

    1993-01-01

    The theory and procedures for determining the characteristics of pressure oscillations in rocket engines with prescribed burning rate oscillations are presented. Pressure and velocity oscillations calculated using this procedure are presented for the Space Shuttle Main Engine (SSME) to show the influence of baffles and absorbers on the burning rate oscillations required to achieve neutral stability. Results of calculations to determine local combustion responses using detailed physical models for injection, atomization, and vaporization with gas phase oscillations in baffled and unbaffled SSME combustors are presented. The contributions of the various physical phenomena occurring in a combustor to oscillations in combustion response were determined.

  17. BLOCKING OSCILLATOR DOUBLE PULSE GENERATOR CIRCUIT

    DOEpatents

    Haase, J.A.

    1961-01-24

    A double-pulse generator, particuiarly a double-pulse generator comprising a blocking oscillator utilizing a feedback circuit to provide means for producing a second pulse within the recovery time of the blocking oscillator, is described. The invention utilized a passive network which permits adjustment of the spacing between the original pulses derived from the blocking oscillator and further utilizes the original pulses to trigger a circuit from which other pulses are initiated. These other pulses are delayed and then applied to the input of the blocking oscillator, with the result that the output from the oscillator circuit contains twice the number of pulses originally initiated by the blocking oscillator itself.

  18. Experimental and theoretical methods to study structural phase transition mechanisms in K{sub 3}WO{sub 3}F{sub 3} oxyfluoride

    SciTech Connect

    Krylov, A.S.; Sofronova, S.N.; Kolesnikova, E.M.; Ivanov, Yu.N.; Sukhovsky, A.A.; Goryainov, S.V.; Ivanenko, A.A.; Shestakov, N.P.; Kocharova, A.G.; Vtyurin, A.N.

    2014-10-15

    The results of structural phase transitions mechanisms study in K{sub 3}WO{sub 3}F{sub 3}oxyfluoride are represented by different experimental and theoretical methods. The structural phase transition anomalies at T{sub 1}=452 K and T{sub 2}=414 K of Raman and IR spectra have been analyzed. Using vibrational spectroscopy methods, the NMR-experiment has been done to clarify the nature of found phase transitions: displacive types or order-disorder types. The model of “disordered” crystal was proposed, and the results of lattice dynamics calculation in frameworks of the generalized Gordon–Kim method of ordered (R3) and “disordered” crystals were compared. The high pressure phases were studied by the Raman technique too. - Graphical abstract: (1) Two possible configuration of octahedra. (2). All phases Raman lines of octahedra. (3) All phases IR lines of octahedra. (4) NMR spectra of all phases. - Highlights: • The results of study oxyfluoride K{sub 3}WO{sub 3}F{sub 3} are represented by Raman, IR, NMR technique. • The high pressure phases were studied by the Raman technique. • The anionic octahedra [WO{sub 3}F{sub 3}]{sup 3−} are not ordered below the both phase transitions. • The ferroelectric phase is realized due to the shift of atoms without F/O ordering. • Both of found phase transitions are close to the second order.

  19. Thalidomide enhances both primary and secondary host resistances to Listeria monocytogenes infection by a neutrophil-related mechanism in female B6C3F1 mice

    SciTech Connect

    Guo, Tai L. . E-mail: tlguo@hsc.vcu.edu; Chi, Rui P.; Karrow, Niel A.; Zhang, Ling X.; Pruett, Stephen B.; Germolec, Dori R.; White, Kimber L.

    2005-12-15

    Previously, we have reported that thalidomide can modulate the immune responses in female B6C3F1 mice. Furthermore, thalidomide immunomodulation increased primary host resistance to intravenously infected Listeria monocytogenes. The present study was intended to evaluate the mechanisms underlying the enhanced host resistance to L. monocytogenes by focusing on the neutrophils. Female B6C3F1 mice were treated intraperitoneally with thalidomide (100 mg/kg) for 15 days. Exposure to thalidomide increased the numbers of neutrophils in the spleens and livers of L. monocytogenes-infected mice when compared to the L. monocytogenes-infected control mice. Additionally, the percentage of neutrophils was also significantly increased after Thd treatment in L. monocytogenes-infected mice. Further studies using antibodies to deplete corresponding cells indicated that thalidomide-mediated increase in primary host resistance (both the moribundity and colony counts in the liver and spleen) to L. monocytogenes infection was due to its effect on neutrophils but not CD8{sup +} T cells or NK cells. Finally, Thd exposure also increased host resistance to secondary host resistance to L. monocytogenes infection, and depletion of neutrophils abolished the protective effect. In conclusion, thalidomide enhanced host resistance to both primary and secondary L. monocytogenes infections by a neutrophil-related mechanism in female B6C3F1 mice.

  20. Evaluation of Manganese Doped Ca5(PO4)3F as a Near Infrared (1-2 microns) Solid-State Laser Material

    NASA Technical Reports Server (NTRS)

    Turner, Matthew; Hoemmerich, Uwe; Loutts, George B.

    1998-01-01

    Tunable solid-state lasers are of enormous interest for applications including fundamental spectroscopy, remote sensing of the earth atmosphere, medical surgery, and optical communications. Efficient and widely tunable lasers have been developed for the 800-1100 nm region based on transition metal doped insulators like e.g. Ti:Sapphire. The development of transition metal lasers operating at longer wavelength, however, has been limited by the luminescence efficiency of existing materials. We are currently evaluating Mn doped Ca5(PO4)3F as a new solid-state laser material for the 1-2 micro-m region. Preliminary spectroscopic studies revealed that Mn:Ca5(PO4)3F exhibits an intense near infrared luminescence which extends from 1100-1300 nm. Based on lifetime measurements we estimated the luminescence quantum efficiency to be as high as 90 deg./0 at room temperature. The near infrared luminescence properties of Mn doped Ca5(PO4)3F and its potential for solid-state laser applications will be discussed in detail.

  1. Collisional quenching reaction rate coefficients of N2 (A3Σu+) by C2F6 and C3F8

    NASA Astrophysics Data System (ADS)

    Suzuki, Susumu; Kuboaki, Masaru; Itoh, Haruo

    2015-09-01

    The collisional quenching reaction rate coefficient of N2 (A3Σu+) by various air pollutant gases were determined from the measurement of the effective lifetime of N2 (A3Σu+) in pure N2 (5-nine) with a small amount of air pollutant gases as an admixture. Derivation of the rate coefficient was performed the waveform analysis of the transient ionization current after turning off the UV light in the Townsend discharge. In this paper, we report that the obtained collisional quenching reaction rate coefficients of N2 (A3Σu+) by C2F6 and C3F8 are (2.3 +/- 1.8) × 10-15 cm3/s and (1.6 +/- 0.8) × 10-14 cm3/s, respectively. Furthermore, we investigate the relationship between the rate coefficient and the mass number of their quenching molecular gases. Firstly, it is confirmed that the rate coefficient take large value with an increase in the mass number of the quenching gases. Secondly, if H atom is included in the gas molecules such as CH4, C2F6 and C3F8 the rate coefficient take large value, but if the molecules including F atom such as C2F6 and C3F8 instead of H atom in this study, more smaller values of the collisional quenching reaction rate coefficient are observed.

  2. Measurements of CCl3F, CCl2F2, CCl4, N2O and SF6 in the Northern Hemisphere stratosphere

    NASA Technical Reports Server (NTRS)

    Leifer, R.; Juzdan, R.

    1985-01-01

    An overview of the Department of Energy's High Altitude Sampling Program and some recent trace gas measurement results are presented. Analysis of whole air samples, collected in pressurized bottles, provides information on stratospheric inventories and distributions for CCl3F, CCl2F2, CCl4, N2O and SF6 in the Northern Hemisphere. Based on a linear regression analysis of the data the estimated mean Northern Hemisphere stratospheric concentration of each gas increased as follows: CCl3F changed from 54 to 142 p1/1 (4/74-11/83); CCl2F2 changed from 133 to 268 p1/1 (4/76-11/83); SF6 changed from 160 to 480 f1/1 (4/74-11/83); CC1, changed from 58 to 91 p1/1 (4/75-11/83); N2O changed from 246 to 261 n1/1 (4/76-11/83). The calculated mean Northern Hemisphere stratospheric concentrations of N2O, CCl3F, CCl2F2, and CCl4 after 1980 show larger than expected fluctuations with time. Recent volcanic activity may be a partial cause for these fluctuations through induced changes in stratospheric dynamical processes.

  3. New oxyfluoride glass with high fluorine content and laser patterning of nonlinear optical BaAlBO{sub 3}F{sub 2} single crystal line

    SciTech Connect

    Shionozaki, K.; Honma, T.; Komatsu, T.

    2012-11-01

    A new oxyfluoride glass of 50BaF{sub 2}-25Al{sub 2}O{sub 3}-25B{sub 2}O{sub 3} (mol. %) with a large fraction of fluorine, i.e., F/(F + O) = 0.4, was prepared using a conventional melt-quenching method in order to synthesize new glass-ceramics containing nonlinear optical oxyfluoride crystals. The refractive index at 632.8 nm and ultra-violet cutoff wavelength of the glass were 1.564 and {approx}200 nm, respectively. Eu{sup 3+} ions in the glass showed a high quantum yield of 88% in the photoluminescence spectrum in the visible region. BaAlBO{sub 3}F{sub 2} crystals (size: 50-100 nm) showing second harmonic generations were formed through the crystallization of the glass. Lines consisting of BaAlBO{sub 3}F{sub 2} crystals were patterned successfully on the glass surface by laser irradiations (Yb:YVO{sub 4} laser with a wavelength of 1080 nm, laser power of 1.1 W, scanning speed of 8 {mu}m/s). High resolution transmission electron microscope observations combined with a focused ion beam technique indicate that BaAlBO{sub 3}F{sub 2} crystals are highly oriented just like a single crystal. The present study proposes that the new oxyfluoride glass and glass-ceramics prepared have a high potential for optical device applications.

  4. The Effect of Neutrino Oscillations on Supernova Light Element Synthesis

    SciTech Connect

    Yoshida, Takashi; Kajino, Toshitaka; Yokomakura, Hidekazu; Kimura, Keiichi; Takamura, Akira; Hartmann, Dieter H.

    2006-07-12

    We investigate light element synthesis through the {nu}-process during supernova explosions considering neutrino oscillations and investigate the dependence of 7Li and 11B yields on neutrino oscillation parameters mass hierarchy and {theta}13. The adopted supernova explosion model for explosive nucleosynthesis corresponds to SN 1987A. The 7Li and 11B yields increase by about factors of 1.9 and 1.3 in the case of normal mass hierarchy and adiabatic 13-mixing resonance compared with the case without neutrino oscillations. In the case of inverted mass hierarchy or nonadiabatic 13-mixing resonance, the increase in 7Li and 11B yields is much smaller. Astronomical observations of 7Li/11B ratio in stars formed in regions strongly affected by prior generations of supernovae would constrain mass hierarchy and the range of {theta}13.

  5. The impact damped harmonic oscillator in free decay

    NASA Technical Reports Server (NTRS)

    Brown, G. V.; North, C. M.

    1987-01-01

    The impact-damped oscillator in free decay is studied by using time history solutions. A large range of oscillator amplitude is covered. The amount of damping is correlated with the behavior of the impacting mass. There are three behavior regimes: (1) a low amplitude range with less than one impact per cycle and very low damping, (2) a useful middle amplitude range with a finite number of impacts per cycle, and (3) a high amplitude range with an infinite number of impacts per cycle and progressively decreasing damping. For light damping the impact damping in the middle range is: (1) proportional to impactor mass, (2) additive to proportional damping, (3) a unique function of vibration amplitude, (4) proportional to 1-epsilon, where epsilon is the coefficient of restitution, and (5) very roughly inversely proportional to amplitude. The system exhibits jump phenomena and period doublings. An impactor with 2 percent of the oscillator's mass can produce a loss factor near 0.1.

  6. Compressible flow in fluidic oscillators

    NASA Astrophysics Data System (ADS)

    Graff, Emilio; Hirsch, Damian; Gharib, Mory

    2013-11-01

    We present qualitative observations on the internal flow characteristics of fluidic oscillator geometries commonly referred to as sweeping jets in active flow control applications. We also discuss the effect of the geometry on the output jet in conditions from startup to supersonic exit velocity. Supported by the Boeing Company.

  7. Geometry of thermal plasma oscillations

    SciTech Connect

    Burton, Da; Noble, A.

    2009-01-22

    We develop a method for investigating the relationship between the shape of a 1-particle distribution and non-linear electrostatic oscillations in a collisionless plasma, incorporating transverse thermal motion. A general expression is found for the maximum sustainable electric field, and is evaluated for a particular highly anisotropic distribution.

  8. Chimera States in Neural Oscillators

    NASA Astrophysics Data System (ADS)

    Bahar, Sonya; Glaze, Tera

    2014-03-01

    Chimera states have recently been explored both theoretically and experimentally, in various coupled nonlinear oscillators, ranging from phase-oscillator models to coupled chemical reactions. In a chimera state, both coherent and incoherent (or synchronized and desynchronized) states occur simultaneously in populations of identical oscillators. We investigate chimera behavior in a population of neural oscillators using the Huber-Braun model, a Hodgkin-Huxley-like model originally developed to characterize the temperature-dependent bursting behavior of mammalian cold receptors. One population of neurons is allowed to synchronize, with each neuron receiving input from all the others in its group (global within-group coupling). Subsequently, a second population of identical neurons is placed under an identical global within-group coupling, and the two populations are also coupled to each other (between-group coupling). For certain values of the coupling constants, the neurons in the two populations exhibit radically different synchronization behavior. We will discuss the range of chimera activity in the model, and discuss its implications for actual neural activity, such as unihemispheric sleep.

  9. High Frequency Stable Oscillate boiling

    NASA Astrophysics Data System (ADS)

    Li, Fenfang; Gonzalez-Avila, Silvestre Roberto; Ohl, Claus Dieter

    2015-11-01

    We present an unexpected regime of resonant bubble oscillations on a thin metal film submerged in water, which is continuously heated with a focused CW laser. The oscillatory bubble dynamics reveals a remarkably stable frequency of several 100 kHz and is resolved from the side using video recordings at 1 million frames per second. The emitted sound is measured simultaneously and shows higher harmonics. Once the laser is switched on the water in contact with the metal layer is superheated and an explosively expanding cavitation bubble is generated. However, after the collapse a microbubble is nucleated from the bubble remains which displays long lasting oscillations. Generally, pinch-off from of the upper part of the microbubble is observed generating a continuous stream of small gas bubbles rising upwards. The cavitation expansion, collapse, and the jetting of gas bubbles are detected by the hydrophone and are correlated to the high speed video. We find the bubble oscillation frequency is dependent on the bubble size and surface tension. A preliminary model based on Marangoni flow and heat transfer can explain the high flow velocities observed, yet the origin of bubble oscillation is currently not well understood.

  10. High-Frequency Gated Oscillator

    NASA Technical Reports Server (NTRS)

    Berard, C. A.

    1982-01-01

    New gated oscillator generates bursts of high-frequency sine waves, square waves, and triangular waves in response to control signals. Each burst starts at zero phase, with tight tolerances on signal amplitude and frequency. Frequencies in megahertz range are made possible by using high-speed comparators and high-speed flip-flop as fast-response threshold detector.

  11. Hydrogen rotation-vibration oscillator

    DOEpatents

    Rhodes, C.K.

    1974-01-29

    A laser system is described wherein molecular species of hydrogen and hydrogen isotopes are induced to oscillate on rotational-vibrational levels by subjecting the hydrogen to a transverse beam of electrons of a narrowly defined energy between about 1 and 5 eV, thereby producing high intensity and high energy output. (Official Gazette)

  12. [Forced Oscillations of DNA Bases].

    PubMed

    Yakushevich, L V; Krasnobaeva, L A

    2016-01-01

    This paper presents the results of the studying of forced angular oscillations of the DNA bases with the help of the mathematical model consisting of two coupled nonlinear differential equations that take into account the effects of dissipation and the influence of an external periodic field. The calculation results are illustrated for sequence of gene encoding interferon alpha 17 (IFNA 17). PMID:27192830

  13. Constant-amplitude RC oscillator

    NASA Technical Reports Server (NTRS)

    Kerwin, W. J.; Westbrook, R. M.

    1970-01-01

    Sinusoidal oscillator has a frequency determined by resistance-capacitance /RC/ values of two charge control devices and a constant-amplitude voltage independent of frequency and RC values. RC elements provide either voltage-control, resistance-control, or capacitance-control of the frequency.

  14. Cubication of Conservative Nonlinear Oscillators

    ERIC Educational Resources Information Center

    Belendez, Augusto; Alvarez, Mariela L.; Fernandez, Elena; Pascual, Immaculada

    2009-01-01

    A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear…

  15. Experimentally Measured Radiative Lifetimes and Oscillator Strengths in Neutral Vanadium

    NASA Astrophysics Data System (ADS)

    Holmes, C. E.; Pickering, J. C.; Ruffoni, M. P.; Blackwell-Whitehead, R.; Nilsson, H.; Engström, L.; Hartman, H.; Lundberg, H.; Belmonte, M. T.

    2016-06-01

    We report a new study of the V i atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24,648 cm‑1 and 37,518 cm‑1 and oscillator strengths for 208 lines between 3040 and 20000 Å from 39 upper energy levels. Thirteen of these oscillator strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and oscillator strengths carried out by Den Hartog et al. and Lawler et al., and thus serves as a means to verify those measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and oscillator strengths. However, we also find evidence that Lawler et al. have systematically underestimated oscillator strengths for lines in the region of 9000 ± 100 Å. We suggest a correction of 0.18 ± 0.03 dex for these values to bring them into agreement with our results and those of Whaling et al. We also report new measurements of hyperfine structure splitting factors for three odd levels of V i lying between 24,700 and 28,400 cm‑1.

  16. Placement and performance analysis of facts-controllers (svc and statcom) for damping oscillation

    NASA Astrophysics Data System (ADS)

    Cakir, Gokhan

    Power system oscillation is one of the major problems in power system operation. If not damped, these oscillations can grow and decrease transmission capacity of the lines which may cause interruption in energy delivery. Stability of power systems is usually associated with insufficient damping of oscillations. Power system oscillations are usually in the range between 0.1 and 2 Hz depending on the number of generators in the system, and can be classified as local or inter-area oscillations. In local mode of oscillations, with frequencies between 1.0 and 2.0 Hz, one generator oscillates against the rest of the system. However, the inter-area oscillations, with frequencies below 1.0 Hz, are related to the phenomenon where synchronous generators in one area oscillate against the ones in other areas. Several methods for damping of power system oscillations are reported in literature. Traditionally, these oscillations have been damped by power system stabilizers. Recently, FACTS-controllers equipped with Power Oscillation Dampers (PODs) have been used efficiently for damping of oscillations; it should be noted that, the main objective of FACTS-controllers is to enhance voltage stability and increase power flow transfer capability the transmission network. The FACTS-controllers used in this thesis are Static Var Compensator (SVC), and STATic synchronous COMpensator (STATCOM). Locations of FACTS-controllers in a power system play an important role in the effective damping of system oscillations. This study proposes the application of the residue factor method to obtain the best locations of FACTS-controllers for damping oscillations. The residue factor used is related to the critical oscillatory modes. Also presented in this study is a comparison of power system stabilizer (PSS) and FACTS-controllers for the enhancement of oscillations damping. The IEEE 14-Bus test system simulated to demonstrate the effectiveness of the proposed method for placement and the comparison

  17. Simulations of Sawtooth Oscillations In CTH

    NASA Astrophysics Data System (ADS)

    Roberds, Nicholas; Guazzotto, Luca; Hanson, James; Maurer, David

    2015-11-01

    Sawteeth are driven relaxation oscillations seen in tokamaks. Experimentally, they can be reproduced reliably. They affect the confinement of the plasma core, and in some circumstances can trigger disruptions. Sawtoothing has been observed in the Compact Toroidal Hybrid (CTH), a tokamak-stellarator hybrid having a non-axisymmetric equilibrium field. We present novel numerical simulations of sawtooth oscillations in this tokamak-stellarator hybrid. Results are contrasted and compared with simulations of a small ohmic tokamak that resembles CTH without the helical stellarator field. We have used NIMROD to conduct these extended-MHD simulations in toroidal geometry. Sawtooth simulations are obtained by starting with a stable ideal MHD equilibrium from VMEC, and driving the central safety factor below unity with an applied loop voltage. The challenges of sawtooth simulations with 3D equilibrium fields are discussed. This material is based upon work supported by Auburn University and the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FG02-03ER54692.

  18. A theory of generalized Bloch oscillations.

    PubMed

    Duggen, Lars; Lew Yan Voon, L C; Lassen, Benny; Willatzen, Morten

    2016-04-20

    Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact calculation is given to confirm this phenomenon. Our results allow for a greater freedom of design for experimentally observing Bloch oscillations. For strongly coupled oscillator systems displaying Bloch oscillations, it is further demonstrated that reordering of oscillators leads to destruction of Bloch oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics. PMID:26986189

  19. Opto-Electronic Oscillator and its Applications

    NASA Technical Reports Server (NTRS)

    Yao, X. S.; Maleki, L.

    1996-01-01

    We present the theoretical and experimental results of a new class of microwave oscillators called opto-electronic oscillators (OEO). We discuss techniques of achieving high stability single mode operation and demonstrate the applications of OEO in photonic communication systems.

  20. Single mode pulsed dye laser oscillator

    DOEpatents

    Hackel, Richard P.

    1992-01-01

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability.

  1. Single mode pulsed dye laser oscillator

    DOEpatents

    Hackel, R.P.

    1992-11-24

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability. 6 figs.

  2. Ground-state cooling of a dispersively coupled optomechanical system in the unresolved sideband regime via a dissipatively coupled oscillator

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Xiang; Wu, Shengjun; Chen, Zeng-Bing; Shikano, Yutaka

    2016-08-01

    In the optomechanical cooling of a dispersively coupled oscillator, it is only possible to reach the oscillator ground state in the resolved sideband regime, where the cavity-mode linewidth is smaller than the resonant frequency of the mechanical oscillator being cooled. In this paper, we show that the dispersively coupled system can be cooled to the ground state in the unresolved sideband regime using an ancillary oscillator, which has a high quality factor and is coupled to the same optical mode via dissipative interaction. The ancillary oscillator has a resonant frequency close to that of the target oscillator; thus, the ancillary oscillator is also in the unresolved sideband regime. We require only a single blue-detuned laser mode to drive the cavity.

  3. Synchronization of Micromechanical Oscillators Using Light

    NASA Astrophysics Data System (ADS)

    Zhang, Mian; Wiederhecker, Gustavo S.; Manipatruni, Sasikanth; Barnard, Arthur; McEuen, Paul; Lipson, Michal

    2012-12-01

    Synchronization, the emergence of spontaneous order in coupled systems, is of fundamental importance in both physical and biological systems. We demonstrate the synchronization of two dissimilar silicon nitride micromechanical oscillators, that are spaced apart by a few hundred nanometers and are coupled through an optical cavity radiation field. The tunability of the optical coupling between the oscillators enables one to externally control the dynamics and switch between coupled and individual oscillation states. These results pave a path toward reconfigurable synchronized oscillator networks.

  4. Fluidic Oscillator Array for Synchronized Oscillating Jet Generation

    NASA Technical Reports Server (NTRS)

    Koklu, Mehti (Inventor)

    2016-01-01

    A fluidic oscillator array includes a plurality of fluidic-oscillator main flow channels. Each main flow channel has an inlet and an outlet. Each main flow channel has first and second control ports disposed at opposing sides thereof, and has a first and a second feedback ports disposed at opposing sides thereof. The feedback ports are located downstream of the control ports with respect to a direction of a fluid flow through the main flow channel. The system also includes a first fluid accumulator in fluid communication with each first control port and each first feedback port, and a second fluid accumulator in fluid communication with each second control port and each second feedback port.

  5. The SD oscillator and its attractors

    NASA Astrophysics Data System (ADS)

    Cao, Q.; Wiercigroch, M.; Pavlovskaia, E.; Grebogi, C.; Michael, J.; Thompson, T.

    2008-02-01

    We propose a new archetypal oscillator for smooth and discontinuous systems (SD oscillator). This oscillator behaves both smooth and discontinuous system depending on the value of the smoothness parameter. New dynamic behaviour is presented for the transitions from the smooth to discontinuous regime.

  6. Mechanical and current oscillations in corroding electrodes

    SciTech Connect

    Teschke, O.; Galembeck, F.; Tenan, M.A.

    1985-06-01

    Mechanical oscillations of the solution meniscus risen around a corroding wire electrode were observed in synchronism with electrical current oscillations. Scanning electron microscopy coupled to microprobe analysis was used to investigate the topochemistry of the system under study. Solution capillarity effects on iron and on iron compounds are related to the oscillations detected in this system.

  7. NOx Emission Reduction by Oscillating Combustion

    SciTech Connect

    2005-09-01

    This project focuses on a new technology that reduces NOx emissions while increasing furnace efficiency for both air- and oxygen-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace.

  8. Scleronomic Holonomic Constraints and Conservative Nonlinear Oscillators

    ERIC Educational Resources Information Center

    Munoz, R.; Gonzalez-Garcia, G.; Izquierdo-De La Cruz, E.; Fernandez-Anaya, G.

    2011-01-01

    A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present…

  9. Quantum phases for a generalized harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Bracken, Paul

    2008-03-01

    An effective Hamiltonian for the generalized harmonic oscillator is determined by using squeezed state wavefunctions. The equations of motion over an extended phase space are determined and then solved perturbatively for a specific choice of the oscillator parameters. These results are used to calculate the dynamic and geometric phases for the generalized oscillator with this choice of parameters.

  10. Squeezed states of damped oscillator chain

    NASA Technical Reports Server (NTRS)

    Manko, O. V.

    1993-01-01

    The Caldirola-Kanai model of one-dimensional damped oscillator is extended to the chain of coupled parametric oscillators with damping. The correlated and squeezed states for the chain of coupled parametric oscillators with damping are constructed. Based on the concept of the integrals of motion, it is demonstrated how squeezing phenomenon arises due to parametric excitation.

  11. Oscillating Cell Culture Bioreactor

    NASA Technical Reports Server (NTRS)

    Freed, Lisa E.; Cheng, Mingyu; Moretti, Matteo G.

    2010-01-01

    dynamic shear (i.e., as required for viability of shear-sensitive cells) to the developing engineered tissue construct. This bioreactor was recently utilized to show independent and interactive effects of a growth factor (IGF-I) and slow bidirectional perfusion on the survival, differentiation, and contractile performance of 3D tissue engineering cardiac constructs. The main application of this system is within the tissue engineering industry. The ideal final application is within the automated mass production of tissue- engineered constructs. Target industries could be both life sciences companies as well as bioreactor device producing companies.

  12. Measuring neutrino oscillation parameters using $\

    SciTech Connect

    Backhouse, Christopher James

    2011-01-01

    MINOS is a long-baseline neutrino oscillation experiment. It consists of two large steel-scintillator tracking calorimeters. The near detector is situated at Fermilab, close to the production point of the NuMI muon-neutrino beam. The far detector is 735 km away, 716m underground in the Soudan mine, Northern Minnesota. The primary purpose of the MINOS experiment is to make precise measurements of the 'atmospheric' neutrino oscillation parameters (Δmatm2 and sin2atm). The oscillation signal consists of an energy-dependent deficit of vμ interactions in the far detector. The near detector is used to characterize the properties of the beam before oscillations develop. The two-detector design allows many potential sources of systematic error in the far detector to be mitigated by the near detector observations. This thesis describes the details of the vμ-disappearance analysis, and presents a new technique to estimate the hadronic energy of neutrino interactions. This estimator achieves a significant improvement in the energy resolution of the neutrino spectrum, and in the sensitivity of the neutrino oscillation fit. The systematic uncertainty on the hadronic energy scale was re-evaluated and found to be comparable to that of the energy estimator previously in use. The best-fit oscillation parameters of the vμ-disappearance analysis, incorporating this new estimator were: Δm2 = 2.32-0.08+0.12 x 10-3 eV2, sin 2 2θ > 0.90 (90% C.L.). A similar analysis, using data from a period of running where the NuMI beam was operated in a configuration producing a predominantly $\\bar{v}$μ beam, yielded somewhat different best-fit parameters Δ$\\bar{m}${sup 2} = (3.36-0.40+0.46(stat.) ± 0.06(syst.)) x 10-3eV2, sin2 2$\\bar{θ}$ = 0.86-0.12_0.11

  13. Control of Oscillation Patterns in a Symmetric Coupled Biological Oscillator System

    NASA Astrophysics Data System (ADS)

    Takamatsu, Atsuko; Tanaka, Reiko; Yamamoto, Takatoki; Fujii, Teruo

    2003-08-01

    A chain of three-oscillator system was constructed with living biological oscillators of phasmodial slime mold, Physarum polycehalum and the oscillation patterns were analyzed by the symmetric Hopf bifurcation theory using group theory. Multi-stability of oscillation patterns was observed, even when the coupling strength was fixed. This suggests that the coupling strength is not an effective parameter to obtain a desired oscillation pattern among the multiple patterns. Here we propose a method to control oscillation patterns using resonance to external stimulus and demonstrate pattern switching induced by frequency resonance given to only one of oscillators in the system.

  14. Oscillating primary transcripts harbor miRNAs with circadian functions

    PubMed Central

    Wang, Haifang; Fan, Zenghua; Zhao, Meng; Li, Juan; Lu, Minghua; Liu, Wei; Ying, Hao; Liu, Mofang; Yan, Jun

    2016-01-01

    The roles of miRNAs as important post-transcriptional regulators in the circadian clock have been suggested in several studies. But the search for circadian miRNAs has led to disparate results. Here we demonstrated that at least 57 miRNA primary transcripts are rhythmically transcribed in mouse liver. Most of these transcripts are under the regulation of circadian transcription factors such as BMAL1/CLOCK and REV-ERBα/β. However, the mature miRNAs derived from these transcripts are either not oscillating or oscillating at low amplitudes, which could explain the inconsistency of different circadian miRNA studies. In order to show that these circadian primary transcripts can give rise to miRNAs with circadian functions, we over-expressed one of them, miR-378, in mouse by adenovirus injection. We found a significant over-representation of circadian oscillating genes under-expressed by miR-378 over-expression in liver. In particular, we observed that miR-378 modulates the oscillation amplitudes of Cdkn1a in the control of cell cycle and Por in the regulation of oxidation reduction by forming partnership with different circadian transcription factors. Our study suggests that circadian transcription of miRNA at primary transcript level can be a good indicator for circadian miRNA functions. PMID:26898952

  15. Recent Developments in the Analysis of Couple Oscillator Arrays

    NASA Technical Reports Server (NTRS)

    Pogorzelski, Ronald J.

    2000-01-01

    This presentation considers linear arrays of coupled oscillators. Our purpose in coupling oscillators together is to achieve high radiated power through the spatial power combining which results when the oscillators are injection locked to each other. York, et. al. have shown that, left to themselves, the ensemble of injection locked oscillators oscillate at the average of the tuning frequencies of all the oscillators. Coupling these arrays achieves high radiated power through coherent spatial power combining. The coupled oscillators are usually designed to produce constant aperture phase. Oscillators are injection locked to each other or to a master oscillator to produce coherent radiation. Oscillators do not necessarily oscillate at their tuning frequency.

  16. Growth oscillation in larger foraminifera

    PubMed Central

    Briguglio, Antonino; Hohenegger, Johann

    2015-01-01

    This work shows the potential for applying three-dimensional biometry to studying cell growth in larger benthic foraminifera. The volume of each test chamber was measured from the three-dimensional model obtained by means of computed tomography. Analyses of cell growth based on the sequence of chamber volumes revealed constant and significant oscillations for all investigated specimens, characterized by periods of approximately 15, 30, 90, and 360 days. Possible explanations for these periods are connected to tides, lunar cycles, and seasonality. The potential to record environmental oscillations or fluctuations during the lifetime of larger foraminifera is pivotal for reconstructing short-term paleoenvironmental variations or for gaining insight into the influence of tides or tidal current on the shallow-water benthic fauna in both recent and fossil environments. PMID:26166912

  17. Analysis of Rattleback Chaotic Oscillations

    PubMed Central

    Stavrinides, Stavros G.; Banerjee, Santo

    2014-01-01

    Rattleback is a canoe-shaped object, already known from ancient times, exhibiting a nontrivial rotational behaviour. Although its shape looks symmetric, its kinematic behaviour seems to be asymmetric. When spun in one direction it normally rotates, but when it is spun in the other direction it stops rotating and oscillates until it finally starts rotating in the other direction. It has already been reported that those oscillations demonstrate chaotic characteristics. In this paper, rattleback's chaotic dynamics are studied by applying Kane's model for different sets of (experimentally decided) parameters, which correspond to three different experimental prototypes made of wax, gypsum, and lead-solder. The emerging chaotic behaviour in all three cases has been studied and evaluated by the related time-series analysis and the calculation of the strange attractors' invariant parameters. PMID:24511290

  18. Electromechanical oscillations in bilayer graphene.

    PubMed

    Benameur, Muhammed M; Gargiulo, Fernando; Manzeli, Sajedeh; Autès, Gabriel; Tosun, Mahmut; Yazyev, Oleg V; Kis, Andras

    2015-01-01

    Nanoelectromechanical systems constitute a class of devices lying at the interface between fundamental research and technological applications. Realizing nanoelectromechanical devices based on novel materials such as graphene allows studying their mechanical and electromechanical characteristics at the nanoscale and addressing fundamental questions such as electron-phonon interaction and bandgap engineering. In this work, we realize electromechanical devices using single and bilayer graphene and probe the interplay between their mechanical and electrical properties. We show that the deflection of monolayer graphene nanoribbons results in a linear increase in their electrical resistance. Surprisingly, we observe oscillations in the electromechanical response of bilayer graphene. The proposed theoretical model suggests that these oscillations arise from quantum mechanical interference in the transition region induced by sliding of individual graphene layers with respect to each other. Our work shows that bilayer graphene conceals unexpectedly rich and novel physics with promising potential in applications based on nanoelectromechanical systems. PMID:26481767

  19. Electromechanical oscillations in bilayer graphene

    PubMed Central

    Benameur, Muhammed M.; Gargiulo, Fernando; Manzeli, Sajedeh; Autès, Gabriel; Tosun, Mahmut; Yazyev, Oleg V.; Kis, Andras

    2015-01-01

    Nanoelectromechanical systems constitute a class of devices lying at the interface between fundamental research and technological applications. Realizing nanoelectromechanical devices based on novel materials such as graphene allows studying their mechanical and electromechanical characteristics at the nanoscale and addressing fundamental questions such as electron–phonon interaction and bandgap engineering. In this work, we realize electromechanical devices using single and bilayer graphene and probe the interplay between their mechanical and electrical properties. We show that the deflection of monolayer graphene nanoribbons results in a linear increase in their electrical resistance. Surprisingly, we observe oscillations in the electromechanical response of bilayer graphene. The proposed theoretical model suggests that these oscillations arise from quantum mechanical interference in the transition region induced by sliding of individual graphene layers with respect to each other. Our work shows that bilayer graphene conceals unexpectedly rich and novel physics with promising potential in applications based on nanoelectromechanical systems. PMID:26481767

  20. Electromechanical oscillations in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Benameur, Muhammed M.; Gargiulo, Fernando; Manzeli, Sajedeh; Autès, Gabriel; Tosun, Mahmut; Yazyev, Oleg V.; Kis, Andras

    2015-10-01

    Nanoelectromechanical systems constitute a class of devices lying at the interface between fundamental research and technological applications. Realizing nanoelectromechanical devices based on novel materials such as graphene allows studying their mechanical and electromechanical characteristics at the nanoscale and addressing fundamental questions such as electron-phonon interaction and bandgap engineering. In this work, we realize electromechanical devices using single and bilayer graphene and probe the interplay between their mechanical and electrical properties. We show that the deflection of monolayer graphene nanoribbons results in a linear increase in their electrical resistance. Surprisingly, we observe oscillations in the electromechanical response of bilayer graphene. The proposed theoretical model suggests that these oscillations arise from quantum mechanical interference in the transition region induced by sliding of individual graphene layers with respect to each other. Our work shows that bilayer graphene conceals unexpectedly rich and novel physics with promising potential in applications based on nanoelectromechanical systems.

  1. Analysis of rattleback chaotic oscillations.

    PubMed

    Hanias, Michael; Stavrinides, Stavros G; Banerjee, Santo

    2014-01-01

    Rattleback is a canoe-shaped object, already known from ancient times, exhibiting a nontrivial rotational behaviour. Although its shape looks symmetric, its kinematic behaviour seems to be asymmetric. When spun in one direction it normally rotates, but when it is spun in the other direction it stops rotating and oscillates until it finally starts rotating in the other direction. It has already been reported that those oscillations demonstrate chaotic characteristics. In this paper, rattleback's chaotic dynamics are studied by applying Kane's model for different sets of (experimentally decided) parameters, which correspond to three different experimental prototypes made of wax, gypsum, and lead-solder. The emerging chaotic behaviour in all three cases has been studied and evaluated by the related time-series analysis and the calculation of the strange attractors' invariant parameters. PMID:24511290

  2. Magnetic Torsional Oscillations in Magnetars

    SciTech Connect

    Sotani, Hajime; Kokkotas, Kostas D.; Stergioulas, Nikolaos

    2009-05-01

    We investigate torsional Alfven oscillations of relativistic stars with a global dipole magnetic field, via 2D numerical simulations. We find that a) there exist two families of quasi-periodic oscillations (QPOs) with harmonics at integer multiples of the fundamental frequency, b) the QPOs are long-lived, c) for the chosen form of dipolar magnetic field, the frequency ratio of the lower to upper fundamental QPOs is about 0.6, independent of the equilibrium model or of the strength of the magnetic field, and d) within a representative sample of EOS and of various magnetar masses, the Alfven QPO frequencies are given by accurate empirical relations that depend only on the compactness of the star and on the magnetic field strength. Compared to the observational frequencies, we also obtain an upper limit on the strength of magnetic field of SGR 1806-20 (if is dominated by a dipolar component) between {approx}3 and 7x10{sup 15} Gauss.

  3. Berry phase in neutrino oscillations

    SciTech Connect

    He Xiaogang; McKellar, Bruce H.J.; Zhang Yue

    2005-09-01

    We study the Berry phase in neutrino oscillations for both Dirac and Majorana neutrinos. In order to have a Berry phase, the neutrino oscillations must occur in a varying medium, the neutrino-background interactions must depend on at least two independent densities, and also there must be CP violation. If the neutrino interactions with matter are mediated only by the standard model W and Z boson exchanges, these conditions imply that there must be at least three generations of neutrinos. The CP violating Majorana phases do not play a role in generating a Berry phase. We show that a natural way to satisfy the conditions for the generation of a Berry phase is to have sterile neutrinos with active-sterile neutrino mixing, in which case at least two active and one sterile neutrinos are required. If there are additional new CP violating flavor changing interactions, it is also possible to have a nonzero Berry phase with just two generations.

  4. Oscillators: Old and new perspectives

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Jayanta K.; Roy, Jyotirmoy

    2014-02-01

    We consider some of the well known oscillators in literature which are known to exhibit interesting effects of nonlinearity. We review the Lindstedt-Poincare technique for dealing with with the nonlinear effects and then go on to introduce the relevance of the renormalization group for the oscillator following the pioneering work of Chen et al. It is pointed out that the traditional Lindstedt-Poincare and the renormalization group techniques have operational connections. We use this to find an unexpected mode softening in the double pendulum. This mode softening prompted us to look for chaos in the double pendulum at low energies-energies that are just sufficient to allow the outer pendulum to rotate (the double pendulum is known to be chaotic at high energies-energies that are greater than that needed to make both pendulums to rotate). The emergence of the chaos is strongly dependent on initial conditions.

  5. Oscillators: Old and new perspectives

    SciTech Connect

    Bhattacharjee, Jayanta K.; Roy, Jyotirmoy

    2014-02-11

    We consider some of the well known oscillators in literature which are known to exhibit interesting effects of nonlinearity. We review the Lindstedt-Poincare technique for dealing with with the nonlinear effects and then go on to introduce the relevance of the renormalization group for the oscillator following the pioneering work of Chen et al. It is pointed out that the traditional Lindstedt-Poincare and the renormalization group techniques have operational connections. We use this to find an unexpected mode softening in the double pendulum. This mode softening prompted us to look for chaos in the double pendulum at low energies-energies that are just sufficient to allow the outer pendulum to rotate (the double pendulum is known to be chaotic at high energies-energies that are greater than that needed to make both pendulums to rotate). The emergence of the chaos is strongly dependent on initial conditions.

  6. Neutrino oscillation results from MINOS

    SciTech Connect

    Sousa, Alexandre; /Oxford U.

    2007-08-01

    The Main Injector Neutrino Oscillation Search (MINOS) long-baseline experiment has been actively collecting beam data since 2005, having already accumulated 3 x 10{sup 20} protons-on-target (POT). MINOS uses the Neutrinos at the Main Injector (NuMI) neutrino beam measured in two locations: at Fermilab, close to beam production, and 735 km downstream, in Northern Minnesota. By observing the oscillatory structure in the neutrino energy spectrum, MINOS can precisely measure the neutrino oscillation parameters in the atmospheric sector. These parameters were determined to be |{Delta}m{sub 32}{sup 2}| = 2.74{sub -0.26}{sup +0.44} x 10{sup -3} eV{sup 2}/c{sup 4} and sin{sup 2}(2{theta}{sub 23}) > 0.87 (68% C.L.) from analysis of the first year of data, corresponding to 1.27 x 10{sup 20} POT.

  7. SPATIAL SEISMOLOGY OF A LARGE CORONAL LOOP ARCADE FROM TRACE AND EIT OBSERVATIONS OF ITS TRANSVERSE OSCILLATIONS

    SciTech Connect

    Verwichte, E.; Foullon, C.; Van Doorsselaere, T.

    2010-07-01

    We present a study of transverse loop oscillations in a large coronal loop arcade, using observations from the Transition Region And Coronal Explorer (TRACE) and Extreme-ultraviolet Imaging Telescope (EIT). For the first time we reveal the presence of long-period transverse oscillations with periods between 24 minutes and 3 hr. One loop bundle, 690 Mm long and with an oscillation period of 40 minutes, is analyzed in detail and its oscillation characteristics are determined in an automated manner. The oscillation quality factor is similar to what has been found earlier for oscillations in much shorter loops. This indicates that the damping mechanism of transverse loop oscillations is independent of loop length or period. The displacement profile along the whole length of the oscillating loop is determined for the first time and consistently between TRACE and EIT. By comparing the observed profile with models of the three-dimensional geometry of the equilibrium and perturbed loop, we test the effect of longitudinal structuring (spatial seismology) and find that the observations cannot unambiguously distinguish between structuring and non-planarity of the equilibrium loop. Associated intensity variations with a similar periodicity are explained in terms of variations in the line-of-sight column depth. Also, we report intensity oscillations at the loop footpoint, which are in anti-phase with respect to the intensity oscillations in the loop body. Lastly, this observation offers the first opportunity to use the transverse oscillations of the arcade to model the Alfven speed profile in the global corona.

  8. Combustor oscillating pressure stabilization and method

    DOEpatents

    Gemmen, Randall S.; Richards, George A.; Yip, Mui-Tong Joseph; Robey, Edward H.; Cully, Scott R.; Addis, Richard E.

    1998-01-01

    High dynamic pressure oscillations in hydrocarbon-fueled combustors typically occur when the transport time of the fuel to the flame front is at some fraction of the acoustic period. These oscillations are reduced to acceptably lower levels by restructuring or repositioning the flame front in the combustor to increase the transport time. A pilot flame front located upstream of the oscillating flame and pulsed at a selected frequency and duration effectively restructures and repositions the oscillating flame in the combustor to alter the oscillation-causing transport time.

  9. Combustor oscillating pressure stabilization and method

    DOEpatents

    Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.H.; Cully, S.R.; Addis, R.E.

    1998-08-11

    High dynamic pressure oscillations in hydrocarbon-fueled combustors typically occur when the transport time of the fuel to the flame front is at some fraction of the acoustic period. These oscillations are reduced to acceptably lower levels by restructuring or repositioning the flame front in the combustor to increase the transport time. A pilot flame front located upstream of the oscillating flame and pulsed at a selected frequency and duration effectively restructures and repositions the oscillating flame in the combustor to alter the oscillation-causing transport time. 7 figs.

  10. Phased array beamforming using nonlinear oscillators

    NASA Astrophysics Data System (ADS)

    Gabbay, Michael; Larsen, Michael L.; Tsimring, Lev S.

    2004-10-01

    We describe a concept in which an array of coupled nonlinear oscillators is used for beamforming in phased array receivers. The signal that each sensing element receives, beam steered by time delays, is input to a nonlinear oscillator. The nonlinear oscillators for each element are in turn coupled to each other. For incident signals sufficiently close to the steering angle, the oscillator array will synchronize to the forcing signal whereas more obliquely incident signals will not induce synchronization. The beam pattern that results can show a narrower mainlobe and lower sidelobes than the equivalent conventional linear beamformer. We present a theoretical analysis to explain the beam pattern of the nonlinear oscillator array.

  11. Topological solitons in optical oscillators

    NASA Astrophysics Data System (ADS)

    Yaparov, V. V.; Taranenko, V. B.

    2016-07-01

    We present an overview of theoretical and experimental works on self-sustaining localized structures—spatial solitons—which can be formed in optical bistable oscillators with laser and/or parametric gain. The main attention is paid to the existence and dynamical properties of spatial solitons containing phase and polarization topological defects including vortices, points of circular polarizations and lines of linear polarization, domain walls and composed domain walls with Néel point topological defects.

  12. Forced Oscillations of Supported Drops

    NASA Technical Reports Server (NTRS)

    Wilkes, Edward D.; Basaran, Osman A.

    1996-01-01

    Oscillations of supported liquid drops are the subject of wide scientific interest, with applications in areas as diverse as liquid-liquid extraction, synthesis of ceramic powders, growing of pure crystals in low gravity, and measurement of dynamic surface tension. In this research, axisymmetric forced oscillations of arbitrary amplitude of viscous liquid drops of fixed volume which are pendant from or sessile on a rod with a fixed or moving contact line and surrounded by an inviscid ambient gas are induced by moving the rod in the vertical direction sinusiodally in time. In this paper, a preliminary report is made on the computational analysis of the oscillations of supported drops that have 'clean' interfaces and whose contact lines remain fixed throughout their motions. The relative importance of forcing to damping can be increased by either increasing the amplitude of rod motion A or Reynolds number Re. It is shown that as the ratio of forcing to damping rises, for drops starting from an initial rest state a sharp increase in deformation can occur when they are forced to oscillate in the vicinity of their resonance frequencies, indicating the incipience of hysteresis. However, it is also shown that the existence of a second stable limit cycle and the occurrence of hysteresis can be observed if the drop is subjected to a so-called frequency sweep, where the forcing frequency is first increased and then decreased over a suitable range. Because the change in drop deformation response is abrupt in the vicinity of the forcing frequencies where hysteresis occurs, it should be possible to exploit the phenomenon to accurately measure the viscosity and surface tension of the drop liquid.

  13. Minicomputer-controlled programmed oscillator

    NASA Technical Reports Server (NTRS)

    Winkelstein, R.

    1971-01-01

    Two programmed oscillators have been constructed, each using a low-cost minicomputer for the calculation and control functions, and each contained in a single rack of equipment. They are capable of operation in a phase-tracking mode as well as a frequency-tracking mode. When given an ephemeris suitable for the planet Venus, these units maintained phase coherence of better than 5 deg rms at 2388 MHz.

  14. B0s Oscillation Results

    SciTech Connect

    Willocq, Stephane

    2002-08-09

    The authors review new studies of the time dependence of B{sub s}{sup 0}-{bar B}{sub s}{sup 0} mixing by the ALEPH, DELPHI and SLD Collaborations, with an emphasis on the different analysis methods used. Combining all available results yields a preliminary lower limit on the oscillation frequency of {Delta}m{sub s} > 14.4 ps{sup -1} at the 95% C.L.

  15. Coherence effects in neutrino oscillations

    NASA Astrophysics Data System (ADS)

    Kiers, Ken; Nussinov, Schmuel; Weiss, Nathan

    1996-01-01

    We study the effect of coherent and incoherent broadening on neutrino oscillations both in vacuum and in the presence of matter (the MSW effect). We show under very general assumptions that it is not possible to distinguish experimentally neutrinos produced in some region of space as wave packets from those produced in the same region of space as plane waves with the same energy distribution.

  16. Enhancement of the Hepatotoxicity of chloroform in B6C3F1 mice by corn oil: implications for chloroform carcinogenesis

    SciTech Connect

    Bull, R.J.; Brown, J.M.; Meierhenry, E.A.; Jorgenson, T.A.; Robinson, M.; Stober, J.A.

    1986-11-01

    A recent study of the ability of chloroform in drinking water to produce cancer reported that male Osborne-Mendel rats developed renal tumors, but that female B6C3F1 mice failed to develop hepatocellular carcinomas. The results obtained in the male Osborne-Mendel rats were comparable to those observed in an earlier study sponsored by the National Cancer Institute (NCI). On the other hand, the lack of an increased incidence of hepatocellular carcinomas in female B6C3F1 mice was in sharp contrast to previously reported results. The doses of chloroform used were comparable to that which produced an 85% incidence in the NCI study. The authors have investigated the extent to which the vehicle might be responsible for the different results in these two studies by examining the differential effects of chloroform when it was administered by gavage using corn oil versus a 2% Emulphor suspension as the vehicle. Male and female B6C3F1 mice were administered chloroform at 60, 130, and 270 mg/kg per day for 90 days. At sacrifice, body and organ weights were measured, and blood was recovered to perform the following serum chemistry measurements (in order of priority): glutamate oxalacetate transaminase (SGOT), lactate dehydrogenase (LDH), blood urea nitrogen (BUN), and triglyceride (TG) levels. The liver was sectioned for histopathological examination. These data indicate that administration of chloroform by corn oil gavage results in more marked hepatotoxic effects than observed when it is provided in an aqueous suspension. A major difference between two recent carcinogenesis bioassays of chloroform in this same mouse strain was the vehicle used.

  17. Automatic oscillator frequency control system

    NASA Technical Reports Server (NTRS)

    Smith, S. F. (Inventor)

    1985-01-01

    A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.

  18. Superimposed oscillations in brane inflation

    SciTech Connect

    Ávila, Santiago; Martin, Jérôme; Steer, Danièle A. E-mail: jmartin@iap.fr

    2014-08-01

    In canonical scalar field inflation, the Starobinsky model (with a linear potential but discontinuous slope) is remarkable in that though slow-roll is violated, both the power-spectrum and bi-spectrum can be calculated exactly analytically. The two-point function is characterised by different power on large and small scales, and a burst of small amplitude superimposed oscillations in between. We extend this analysis to Dirac Born Infeld (DBI) inflation, for which generalised slow-roll is violated at the discontinuity and a rapid variation in the speed of sound c{sub S} occurs. In an attempt to characterise the effect of non-linear kinetic terms on the oscillatory features of the primordial power-spectrum, we show that the resulting power spectrum has a shape and features which differ significantly from those of the standard Starobinsky model. In particular, when c{sub S} is small, the power-spectrum now takes very similar scale invariant values on large and small scales, while on intermediate scales it is characterised by much larger amplitude and higher frequency superimposed oscillations. We also show that calculating non-Gaussianities in this model is a complicated but interesting task since all terms in the cubic action now contribute. Investigating whether the superimposed oscillations could fit to the Planck Cosmic Microwave Background (CMB) data (for instance by explaining the large scale Planck anomalies) with, at the same time, small non-Gaussianities remains an intriguing and open possibility.

  19. Rijke-type thermoacoustic oscillations

    NASA Astrophysics Data System (ADS)

    Beke, Tamas

    2011-03-01

    Thermoacoustic instability can appear in any thermal device when the unsteady heat transfer is favourably coupled with the fluctuations of acoustic pressure. In this paper, we present a project type of physical measuring and modelling task; the aim of our project is to help our students increase their knowledge of thermoacoustics. Our paper proposes several experiments and describes some tools' setups that are easy to obtain and work with. Free software is offered to analyse the signals with a personal computer. In this paper, the basis of standing wave theory and the tie between thermodynamics and acoustical oscillations are also discussed; some devices and technical applications of thermoacoustic oscillations are presented. The objective of this paper is to present the theory of frequency shifting of thermoacoustic oscillations as well. The frequencies of the acoustic modes in the excited state are of interest for practical purposes; the differences between the calculated and the measured values of these frequencies are shown. The behaviour of the properties of the exited modes shows the complexity of the real thermoacoustic systems; the mathematical modelling intended to simulate the effect of frequency shifting is observed in tests. We think that these experiments can be implemented in physics courses on thermodynamics for graduates or specialized courses for undergraduates.

  20. Micro-machined resonator oscillator

    DOEpatents

    Koehler, D.R.; Sniegowski, J.J.; Bivens, H.M.; Wessendorf, K.O.

    1994-08-16

    A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a telemetered sensor beacon'' that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20--100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available. 21 figs.