RESUMO
Recent optomechanical experiments have observed nonclassical properties in macroscopic mechanical oscillators. A key indicator of such properties is the asymmetry in the strength of the motional sidebands produced in the probe electromagnetic field, which is originated by the noncommutativity between the oscillator ladder operators. Here we extend the analysis to a squeezed state of an oscillator embedded in an optical cavity, produced by the parametric effect originated by a suitable combination of optical fields. The motional sidebands assume a peculiar shape, related to the modified system dynamics, with asymmetric features revealing and quantifying the quantum component of the squeezed oscillator motion.
RESUMO
We report the experimental observation of two-mode squeezing in the oscillation quadratures of a thermal micro-oscillator. This effect is obtained by parametric modulation of the optical spring in a cavity optomechanical system. In addition to stationary variance measurements, we describe the dynamic behavior in the regime of pulsed parametric excitation, showing an enhanced squeezing effect surpassing the stationary 3 dB limit. While the present experiment is in the classical regime, our technique can be exploited to produce entangled, macroscopic quantum optomechanical modes.
RESUMO
The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity.
RESUMO
We report the confinement of an optomechanical micro-oscillator in a squeezed thermal state, obtained by parametric modulation of the optical spring. We propose and implement an experimental scheme based on parametric feedback control of the oscillator, which stabilizes the amplified quadrature while leaving the orthogonal one unaffected. This technique allows us to surpass the -3 dB limit in the noise reduction, associated with parametric resonance, with a best experimental result of -7.4 dB. While the present experiment is in the classical regime, in a moderately cooled system our technique may allow squeezing of a macroscopic mechanical oscillator below the zero-point motion.
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We analyze heat and work fluctuations in the gravitational wave detector AURIGA, modeled as a macroscopic electromechanical oscillator in contact with a thermostat and cooled by an active feedback system. The oscillator is driven to a steady state by the feedback cooling, equivalent to a viscous force. The experimentally measured fluctuations are in agreement with our theoretical analysis based on a stochastically driven Langevin system. The asymmetry of the fluctuations of the absorbed heat characterizes the oscillator's nonequilibrium steady state and reveals the extent to which a feedback cooled system departs from equilibrium in a statistical mechanics perspective.
RESUMO
We apply a feedback cooling technique to simultaneously cool the three electromechanical normal modes of the ton-scale resonant-bar gravitational wave detector AURIGA. The measuring system is based on a dc superconducting quantum interference device (SQUID) amplifier, and the feedback cooling is applied electronically to the input circuit of the SQUID. Starting from a bath temperature of 4.2 K, we achieve a minimum temperature of 0.17 mK for the coolest normal mode. The same technique, implemented in a dedicated experiment at subkelvin bath temperature and with a quantum limited SQUID, could allow to approach the quantum ground state of a kilogram-scale mechanical resonator.
RESUMO
At the time when the giant flare of SGR1806-20 occurred, the AURIGA "bar" gravitational-wave (GW) detector was on the air with a noise performance close to stationary Gaussian. This allows us to set relevant upper limits, at a number of frequencies in the vicinities of 900 Hz, on the amplitude of the damped GW wave trains, which, according to current models, could have been emitted, due to the excitation of normal modes of the star associated with the peak in x-ray luminosity.
RESUMO
The production of colony-stimulating factor (CSF) by murine transformed cells was investigated in 10 cell lines derived from spontaneous or chemically induced tumours and from cells transformed by SV40 or Moloney-MSV; histologic types included carcinomas, sarcomas and melanoma. Nine of 10 supernatants contained CSF activity as judged by in vitro proliferation and differentiation of normal murine monocytic and granulocytic progenitors in agar cultures. Tumours induced with CSF-producing cells caused alterations of haemopoiesis which can include leukocytosis, granulocytosis and splenomegaly. Haemopoietic alterations were also evident in the absence of a local tumour in mice bearing large experimental lung metastases. Production of CSF seems to be a frequent finding among murine cell lines, and its biological and immunological consequences on host-tumour relationships should be taken into account.
Assuntos
Fatores Estimuladores de Colônias/metabolismo , Hematopoese , Células Tumorais Cultivadas/metabolismo , Animais , Linhagem Celular Transformada , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BLRESUMO
The effect of various antineoplastic drugs (1-beta-D-arabinofuranosylcytosine, 5-azacytidine, cisplatin, dactinomycin, epirubicin, vincristine, and the activated metabolite of cyclophosphamide, mafosfamide) on cell differentiation in vitro was investigated using a human alveolar rhabdomyosarcoma cell clone, RMZ-RC2. These cells are able to differentiate spontaneously from small mononuclear proliferating elements to terminal, extremely elongated multinuclear structures resembling myotubes; morphological differentiation is accompanied by the expression of myosins, in particular the embryonic isoform, which was used in this study as a specific marker of myogenic differentiation. The proportion of differentiated myosin-positive cells, which was around 10-15% in control cultures 10-15 days after seeding, was increased by some drug treatments up to 30-40%; the proportion of multinuclear elements was also increased. 1-beta-D-arabinofuranosylcytosine and 5-azacytidine were the most effective drugs, while dactinomycin had no effect; other molecules ranked in between. Since significant increments were usually observed after treatment with drug doses inhibiting cell growth, the kinetic behavior of the absolute number of myosin-positive cells or nuclei was analyzed to assess whether some effects could be due to a negative selection of proliferating, undifferentiated cells. This appeared to be the case for vincristine and epirubicin, while 1-beta-D-arabinofuranosylcytosine, 5-azacytidine, and, to a lesser degree, mafosfamide and cisplatin actually seemed to increase differentiation ability.
Assuntos
Antineoplásicos/farmacologia , Diferenciação Celular/efeitos dos fármacos , Músculos/citologia , Rabdomiossarcoma/patologia , Azacitidina/farmacologia , Divisão Celular/efeitos dos fármacos , Fusão Celular , Cisplatino/farmacologia , Ciclofosfamida/farmacologia , Citarabina/farmacologia , Humanos , Técnicas In Vitro , Miosinas/metabolismo , Células Tumorais CultivadasRESUMO
Tumorigenic and metastatic potential were studied in relation to class I MHC expression in four different SV40-transformed BALB/c cell lines. All the lines studied, tumorigenic or not, expressed both H-2Kd and Dd, so MHC antigens did not seem to be involved in the control of SV40-transformed cells' growth in vivo. Lung metastases were observed in all tumour-bearing mice. Cells cultured after in vivo passage, obtained either from tumour tissue or from individual lung metastases, still expressed similar levels of H-2d antigens, thus suggesting that tumour growth and metastasis do not occur through the selection of variants with altered MHC expression.
Assuntos
Genes MHC Classe I , Antígenos H-2/imunologia , Metástase Neoplásica , Neoplasias Experimentais/patologia , Animais , Antígenos Transformantes de Poliomavirus/imunologia , Soro Antilinfocitário , Testes de Carcinogenicidade , Linhagem Celular Transformada , Citotoxicidade Imunológica , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias Experimentais/imunologia , Vírus 40 dos SímiosRESUMO
The in vivo covalent binding of 14C-pentachloroethane to DNA, RNA and proteins of rats and mouse organs was detected 22 hr after i.p. injection. The covalent binding index, calculated on the liver labeling was comparable to those of compounds considered as weak-moderate initiators. Like other haloalkanes, 14C-pentachloroethane was bioactivated in in vitro cell-free system by both microsomal and cytosolic enzymatic fractions from mouse and rat organs to react covalently with DNA and other macromolecules. The binding extents obtained from in vitro incubation and the binding values detected after in vivo administration of labeled pentachloroethane were comparable each other and showed a high correlation with oncogenic potency index of this compound. This result confirms the efficiency of in vitro binding as short-term test of genotoxicity prediction.
Assuntos
DNA/metabolismo , Etano/análogos & derivados , Hidrocarbonetos Clorados/metabolismo , Mutagênicos/metabolismo , Animais , Biotransformação , Etano/metabolismo , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Testes de Mutagenicidade , Ratos , Ratos Endogâmicos , Especificidade da EspécieRESUMO
Hexachloroethane (HCE) binds to macromolecules of rat and mouse both in vivo and in vitro after metabolic activation. The covalent binding index (CBI) to liver DNA in vivo is comparable to that of compounds classified as weak-moderate initiators and is of approximately the same order of magnitude as those of other halocompounds such as 1,2-dichloroethane. HCE is bioactivated in vitro by microsomal enzymatic systems from murine liver and kidney and, to a greater extent, by cytosolic fractions from all assayed organs. HCE is less reactive than 1,1,2,2-tetrachloroethane, which is more toxic and oncogenic. The ability of hexachloroethane and five other chloroethanes to react covalently with mouse liver DNA both in vivo and in vitro parallels the relative oncogenic potency of these hepatocarcinogenic chemicals in mouse liver.
Assuntos
DNA/metabolismo , Etano/análogos & derivados , Hidrocarbonetos Clorados/metabolismo , Animais , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Ligação Proteica , RNA/metabolismo , Ratos , Ratos EndogâmicosAssuntos
Adenocarcinoma/imunologia , Antígenos HLA/genética , Interferon gama/farmacologia , Complexo Principal de Histocompatibilidade , Neoplasias Mamárias Experimentais/imunologia , Melanoma Experimental/imunologia , Metástase Neoplásica , Adenocarcinoma/patologia , Animais , Linhagem Celular , Antígenos H-2/genética , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/secundário , Neoplasias Mamárias Experimentais/patologia , Melanoma Experimental/patologia , Camundongos , Camundongos Endogâmicos BALB CRESUMO
14C-Perchloroethylene is covalently bound to DNA, RNA and proteins of rat and mouse organs in vivo after ip injection. Covalent Binding Index values are typical of weak-moderate and weak initiators, for mouse and rat liver, respectively. The greater amounts of labelings detected in mouse liver and in rat kidney macromolecules are consistent with the known toxic and carcinogenic actions of this compound. In vitro binding of perchloroethylene to nucleic acids and proteins proceeds through the involvement of the P-450-dependent mixed function oxidase system from liver microsomes. Kidney, lung and stomach microsomal fractions are uneffective. Cytosolic enzymes from all assayed organs are much more efficient than liver microsomes in bioactivating the compound. GSH addition to liver microsomal system greatly enhances binding extent. This observation suggests that GSH plays a role in the binding of perchloroethylene metabolites as for symmetrically substituted haloethanes.
Assuntos
DNA/metabolismo , Tetracloroetileno/metabolismo , Animais , Citosol/metabolismo , Mucosa Gástrica/metabolismo , Rim/metabolismo , Fígado/metabolismo , Pulmão/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microssomos/metabolismo , Ligação Proteica , RNA/metabolismo , Ratos , Ratos Endogâmicos , Tetracloroetileno/toxicidadeRESUMO
Epirubicin, at concentrations ranging between 10(-7) and 10(-13) M, was assayed in semisolid cultures of human normal hemopoietic cells and in liquid cultures of 5 different human leukemic cell lines. The growth of all normal hemopoietic progenitor cells was inhibited by the higher drug concentrations; at the lowest concentration, only CFU-E and 7th-day CFU-GM were not inhibited. On the other hand, leukemic cells were sensible only to the higher concentration of epirubicin, which, nevertheless, was not fully inhibitory. Leukemic cell differentiation was not promoted by the drug, as evidenced by a panel of monoclonal antibodies, by cytochemistry and by functional tests. These results suggest a marked in vitro myelotoxicity of epirubicin, that does not appear to be compensated by a powerful control of leukemic cell proliferation.
Assuntos
Doxorrubicina/farmacologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Leucemia/sangue , Anticorpos Monoclonais , Medula Óssea/efeitos dos fármacos , Ensaio de Unidades Formadoras de Colônias , Epirubicina , Histocitoquímica , Humanos , Técnicas In Vitro , Fagocitose , Timidina/metabolismo , Células Tumorais Cultivadas/efeitos dos fármacosRESUMO
The relationship between major histocompatibility complex (MHC) antigens and metastasis was investigated on B16 melanoma variants. B16 cell lines express low amounts of murine MHC (H-2) antigens. A high expression can be induced in line B16-A by in vitro treatment with immune interferon (IFN-gamma) or by in vivo transplant in allogeneic mice. The increase of H-2 antigens correlated with an enhancement of lung colonization in young syngeneic mice. The higher metastatic capacity of B16-A cells with induced high levels of H-2 antigens was observed also in adult mice and in young mice pretreated with cyclophosphamide. These results were confirmed investigating the behaviour of a mutant B16 clone (B78H1) which was selectively resistant to the H-2-inducing action of IFN-gamma: lung colonization ability was not increased by IFN pretreatment. The study of variants derived from individual B16-A lung colonies revealed a wide range of H-2 levels. Variants with a low expression had a low colonization ability; one out of two variants with a high H-2 expression also was poorly colonizing. IFN-gamma-mediated H-2 expression appeared to act as an enhancer, rather than a determinant of B16 metastatic capacity.
Assuntos
Antígenos H-2/imunologia , Interferon gama/farmacologia , Complexo Principal de Histocompatibilidade , Metástase Neoplásica/imunologia , Animais , Linhagem Celular , Citotoxicidade Imunológica , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/secundário , Masculino , Melanoma/imunologia , Melanoma/patologia , Camundongos , Camundongos Endogâmicos , Transplante de Neoplasias , Proteínas Recombinantes/farmacologiaRESUMO
The relationship between production of Colony-Stimulating Factor (CSF) and metastasis has been investigated in the TS/A murine model. CSF production was determined in TS/A cell variants isolated through serial in vivo selection of lung metastatic nodules induced by intravenous or subcutaneous injection of tumor cells (artificial and spontaneous metastases, respectively). All the cell variants selected for high artificial metastatic ability produced higher amounts of GM-CSF in vitro and stronger haematological alterations in vivo than cells obtained by serial selection of spontaneous metastases. Our data suggest that the late, rather than the early, steps of the metastatic process could be enhanced by GM-CSF production.
Assuntos
Substâncias de Crescimento/biossíntese , Metástase Neoplásica , Neoplasias Experimentais/patologia , Animais , Feminino , Fator Estimulador de Colônias de Granulócitos e Macrófagos , Neoplasias Pulmonares/secundário , Camundongos , Camundongos Endogâmicos BALB C , Células Tumorais CultivadasRESUMO
On the basis that inhibition of cell proliferation may play a role in the differentiation process, we have studied the effect of the antineoplastic drug epirubicin, an antibiotic of the anthracycline group, on human neuroblastoma cell lines SK-N-MC, SK-N-SH, SJ-N-KP, TS12 and AF8. Epirubicin induced morphological and biochemical differentiation in these cultured cell lines; treatment with it stimulated the outgrowth of neurites and increased acetylcholinesterase activity.