Bubble-like Structure Research Articles

Parthenogenetic Embryo-Like Structures in the Human Ovarian Surface Epithelium Cell Culture in Postmenopausal Women with No Naturally Present Follicles and Oocytes

Little is known about parthenogenesis in the human ovary. What is known is related to patients with teratoma in their medical history. Ovarian surface epithelium (OSE) was often proposed as a source of ovarian stem cells with an embryonic character in the past, and was also termed "germinal epithelium." The aim of this study was to isolate putative stem cells from OSE scrapings, to set up an OSE cell culture, to follow the in vitro oogenesis and possible formation of parthenogenetic embryos in 21 postmenopausal women with no naturally present follicles and oocytes. Small round cells with a bubble-like structure and with a diameter from 2 to 4 microm were isolated from the material obtained by OSE scrapings in all women. They expressed early embryonic developmental markers such as stage-specific embryonic antigen-4 (SSEA-4) surface antigen and Oct-4, Nanog, Sox-2, and c-kit transcription factors. These cells were separated by density gradient centrifugation and grown in vitro, where they proliferated and formed embryoid body-like structures. Their markers of pluripotency such as telomerase activity were decreased during in vitro culture and they did not form teratoma after the injection into SCID mice. Some of them grew intensively and reached a diameter of approximately 20 microm after 5-7 days of culture. In the OSE cell culture, oocyte-like cells developed among them, which reached a diameter up to 95 mum, and expressed Oct-4, c-kit, VASA, and ZP2 transcription markers after 20 days of culture. Some of them expressed a zona pellucida-like structure and rarely germinal vesicle- and polar body-like structures. At the same time, parthenogenetic blastocyst-like structures developed, which expressed transcription markers Oct-4, Sox-2, and Nanog and were normal for chromosomes X, Y, 13, 16, 18, 21, and 22. In conclusion, the discovered cells expressed embryonic stem cell markers, gave rise to embryoid body-, oocyte-, and blastocyst-like structures, and might be involved in the human reproduction and formation of ovarian tumors.

Putative stem cells with an embryonic character isolated from the ovarian surface epithelium of women with no naturally present follicles and oocytes

There have been some proposals that stem cells exist in the ovarian surface epithelium (OSE) of the adult human ovary; however, no direct evidence of such cells has been given until now. The aim of this study was to isolate the putative ovarian stem cells (OSCs) from the OSE layer in women with no naturally present oocytes and follicles—20 postmenopausal women and five women with premature ovarian failure. Small round cells with a bubble-like structure and diameters from 2 to 4 μm were isolated from the material obtained by OSE scraping. They expressed early embryonic developmental markers such as stage-specific embryonic antigen-4 and Oct-4, Nanog, Sox-2, and c-kit transcription markers, and they displayed prominent c-kit immunohistochemical staining. These cells were separated by density gradient centrifugation and grown in vitro, where they proliferated. Some of them grew intensively and reached a diameter of approximately 20 μm after 5–7 days. In the OSE cell culture, oocyte-like cells developed, which reached a diameter of up to 95 μm and expressed Oct-4A, Oct-4B, c-kit, VASA, and ZP2 transcription markers, corresponding to early oocytes. They did not express SCP3 meiotic marker. In conclusion, the discovered cells are proposed to represent the adult OSCs with the expression of embryonic stem cell markers. The expression of germ lineage marker c-kit points toward their primordial germ cell ancestry. A new term “embryonic-like stem cells of the adult” is proposed for embryonic-like stem cells that might persist in various tissues and organs of adults. These findings could be used for further studies aimed at the autologous treatment of ovarian infertility and degenerative diseases.

Evidence of cold bubble-like structure in START density limit plasmas

Cold bubble (CB) structures were observed in START density limit studies for the first time in a low aspect ratio tokamak. They seem related to minor and major disruption processes, clearly identified here as a trigger to those events. Enormous discrepancies on the CB velocities in several devices are reported. This shows that the physical mechanisms related to the time scales for its propagation should be revised. Several models related to CB formation and its role in the disruptive process or just in a plasma with the presence of sawteeth qualitatively predict a great part of the observations.

Localized Enhancements of Fe+10Density in the Corona as Observed in Fexi789.2 nm during the 2006 March 29 Total Solar Eclipse

The first ever image of the full solar corona in the Fe XI 789.2 nm spectral line was acquired during the total solar eclipse of 2006 March 29. Several striking features stand out in the processed image: (1) The emission extended out to at least 3 R☉ in streamers. (2) A bubble-like structure, occupying a cone of about 45° and reaching out to 1 R☉ above the limb, was observed southward of a bright active region complex close to the limb. (3) Localized intensity enhancements were found in different parts of the corona at heights ranging from 1.2 to 1.5 R☉. (4) Striations extended out to the edge of the field of view above an almost north-south-oriented prominence. Comparison with the corresponding white-light image taken simultaneously during the eclipse showed no evidence for these localized enhancements, and the bubble-like structure and striations, while present, did not stand out in the same manner. The extent of the Fe XI emission is attributed to the dominance of radiative over collisional excitation in the formation of that spectral line. The localized intensity enhancements, observed only in Fe XI and not in white light, are a signature of localized increases in Fe+10 density relative to electron density. These are the first observations to show direct evidence of localized heavy ion density enhancements in the extended corona. They point to the importance of implementing observations of the Fe XI 789.2 nm line with existing or future coronagraphs for the exploration of the physical processes controlling the behavior of heavy ions in different source regions of the solar wind.

Dual priming oligonucleotide system for the multiplex detection of respiratory viruses and SNP genotyping of CYP2C19 gene

Successful PCR starts with proper priming between an oligonucleotide primer and the template DNA. However, the inevitable risk of mismatched priming cannot be avoided in the currently used primer system, even though considerable time and effort are devoted to primer design and optimization of reaction conditions. Here, we report a novel dual priming oligonucleotide (DPO) which contains two separate priming regions joined by a polydeoxyinosine linker. The linker assumes a bubble-like structure which itself is not involved in priming, but rather delineates the boundary between the two parts of the primer. This structure results in two primer segments with distinct annealing properties: a longer 5′-segment that initiates stable priming, and a short 3′-segment that determines target-specific extension. This DPO-based system is a fundamental tool for blocking extension of non-specifically primed templates, and thereby generates consistently high PCR specificity even under less than optimal PCR conditions. The strength and utility of the DPO system are demonstrated here using multiplex PCR and SNP genotyping PCR.

2D hydrodynamic simulations of generation of high-current proton beams by relativistic skin-layer laser-plasma interaction

The properties of fast proton beam generation by skin-layer ponderomotive acceleration (SLPA) induced by a short (< 1 ps) laser pulse are studied using 2D two-fluid relativistic code. It is found that both for subrelativistic and relativistic laser intensities, the crucial parameter determining the spatial structure and angular divergence (Θ b) of the proton beam is the ratio d L/L n, where d L is the laser beam diameter and L n is the density gradient scale length of preplasma in front of the target. When this ratio is relatively small (< 10), the proton beam generated at relativistic laser intensities has a bubble-like structure and Θ is large. When d L is at least tens times greater than L n, the transverse distribution of the proton density and the proton current density in the beam follow the spatial shape of the laser beam and Θ b is small. In the last case, highly collimated high-current (MA) proton beams can be produced by SLPA at relativistic laser intensities.

Reconstructed global feature of an interplanetary disturbance for the full-halo coronal mass ejection event on 1999 September 20

Traveling interplanetary (IP) disturbances associated with the full-halo coronal mass ejection (CME) which occurred on September 20, 1999, were observed clearly with the 327-MHz interplanetary scintillation (IPS) system of the Solar-Terrestrial Environment Laboratory of Nagoya University. In this study, we retrieved the global features of the IP disturbances by fitting a three-dimensional model to our IPS data. We obtained a best fit model, which had a bubble-like structure with a center axis shifted south with respect to the Sun–Earth line and a nearly isotropic angular span. We believe this feature represents the compression region between the IP shock and the CME. The reconstructed global feature was found to be in good agreement with in situ measurements by ACE and the Nozomi spacecraft, which were situated near the earth and distant from the Earth, respectively, at the time of the full-halo CME event.

Effects of shock compression on powder mixtures of nickel and boron

A shock recovery experiment for mixing nickel and boron powder was performed by a flyer plate impact technique. The flyer velocity was in the range of 0.7–1.4 km s −1, and the shock pressure was calculated to be 4–11 GPa by the impedance matching method. The shock-treated sample was characterized by X-ray diffraction analysis, optical microscopy and transmission electron microscopy. The shock wave induces a reaction between the nickel and boron powder particle. The amount of the shock-synthesized intermetallic compounds is increased with increasing shock pressure. At a shock pressure of 11 GPa, a bubble-like structure is formed by the interaction between the powder particles. Transmission electron microscopy analysis reveals the presence of nano-scale nickel particles in the recovered samples. The shock compression proved useful for the formation of unique microstructures.

Effects of Turbulence on Flame Structure and NOx Emission of Turbulent Jet Non-Premixed Flames in High-Temperature Air Combustion

Turbulent jet non-premixed flame under the conditions of High Temperature Air Combustion (HiCOT) was investigated. Air diluted with nitrogen was preheated up to about 1300K. Propane was injected through a fuel tube parallel to the preheated airflow. LDV measurement of turbulence, CH-PLIF for reaction zone visualization, and NOx concentration measurements in the burnt gas were performed and the relations between these characteristics were examined. Results showed that turbulence intensity generated by perforated plate installed upstream of the fuel tube was high at high-temperature airflow due to high velocity compared with that at room temperature airflow when the flow rate was controlled to keep the excess air ratio constant regardless of preheating. The reaction zone represented by the CH-PLIF images still had a thin structure even in the HiCOT condition of oxygen concentration of 8vol.%. The flow turbulence in the combustion duct played a significant role in decreasing NOx emission. Due to turbulence, flame was broken and a bubble-like flame structure was generated, especially in the lifted flame cases, implying that the burning fuel lumps flow a considerable distance in air with a low oxygen concentration and generate uniform heat release profiles in HiCOT furnaces.

Fragmentation path of excited nuclear systems

We perform a study of the fragmentation path of excited nuclear sources, within the framework of a stochastic mean-field approach. We consider the reaction 129Xe + 119Sn at two beam energies: 32 and 50 MeV/ A, for central collisions. It is observed that, after the compression phase the system expands towards a dilute configuration from which it may recontract or evolve into a bubble-like structure. Then fragments are formed through the development of volume and/or surface instabilities. The two possibilities co-exist at 32 MeV/ A, leading to quite different fragment partitions, while at 50 MeV/ A the hollow configuration is observed in all events. Large variances are recovered in a way fully consistent with the presence of spinodal decomposition remnants. Kinematical properties of fragments are discussed and suggested as observables very sensitive to the dominant fragment production mechanism. A larger radial collective flow is observed at 50 MeV/ A, in agreement with experiments.

Annealing control primer system for improving specificity of PCR amplification

A novel primer designed to improve the specificity of PCR amplification, called the annealing control primer (ACP), comprises a tripartite structure with a polydeoxyinosine [poly(dI)] linker between the 3' end target core sequence and the 5' end nontarget universal sequence. We show that this ACP linker prevents annealing of the 5' end nontarget sequence to the template and facilitates primer hybridization at the 3' end to the target sequence at specific temperatures, resulting in a dramatic improvement of annealing specificity. The effect of this linker is demonstrated by the incorporation of ACP sequences as primers during the amplification of target nucleotide sequence and as hybridization probes in the genotyping of single nucleotide polymorphisms. This is the first report to show that a poly(dI) linker between two different sequences of ACP forms a bubble-like structure and disrupts or destabilizes DNA duplex formation at certain annealing temperatures.

Instability at interface between reconnection jet and pre-existing plasma sheet

When a reconnection jet encounters a pre-existing plasma sheet standing ahead of it, the interface between the two where both plasma and magnetic field are compressed becomes unstable and develops a bubble-like structure. We have conducted three-dimensional hybrid simulations (ions as particles and electrons as massless charge neutralizing fluid) of this instability. We suggest that this instability generates a variety of plasma flows and field configurations which may have relevance to some magnetospheric phenomena.

The Role of Tip Leakage Vortex Breakdown in Compressor Rotor Aerodynamics

The breakdown of tip leakage vortex has been investigated on a low-speed axial compressor rotor with moderate blade loading. Effects of the breakdown on the rotor aerodynamics are elucidated by Navier–Stokes flow simulations and visualization techniques for identifying the breakdown. The simulations show that the leakage vortex breakdown occurs inside the rotor at a lower flow rate than the peak pressure rise operating condition. The breakdown is characterized by the existence of the stagnation point followed by a bubblelike recirculation region. The onset of breakdown causes significant changes in the nature of the tip leakage vortex: large expansion of the vortex and disappearance of the streamwise vorticity concentrated in the vortex. The expansion has an extremely large blockage effect extending upstream of the leading edge. The disappearance of the concentrated vorticity results in no rolling-up of the vortex downstream of the rotor and the disappearance of the pressure trough on the casing. The leakage flow field downstream of the rotor is dominated by the outward radial flow, resulting from the contraction of the bubblelike structure of the breakdown region. It is found that the leakage vortex breakdown plays a major role in characteristic of rotor performance at near-stall conditions. As the flow rate is decreased from the peak pressure rise operating condition, the breakdown region grows rapidly in the streamwise, spanwise, and pitchwise directions. The growth of the breakdown causes the blockage and the loss to increase drastically. Then, the interaction of the breakdown region with the blade suction surface gives rise to the three-dimensional separation of the suction surface boundary layer, thus leading to a sudden drop in the total pressure rise across the rotor.

Tracks in YIG induced by MeV C 60 ions

Samples of yttrium iron garnet (Y 3Fe 5O 12 or YIG) were irradiated at 300 K with MeV C 60-ions at normal and tilted incidence. As observed by transmission electron microscopy, the cluster ions create amorphous and continuous tracks. Craters generated both at the entrance and exit surfaces of the samples are clearly visible at tilted incidence. Moreover, hillocks are seen at the entrance and exit of the tracks. On the sample surface matter ejected from the tracks has been deposited. Some of the tracks induced by high energy C 60-ions contain a “bubble-like structure” inside the amorphous part of the tracks, which appears only in very thin zones of the samples and when the projectiles exit from the sample. This is in contrast to the tracks created by smaller cluster ions and by GeV heavy ions for which no structure was seen.

VII. REDSHIFT SURVEYS OF EMISSION-LINE GALAXIES

ABSTRACT The usefulness of employing samples of emission-line galaxies as alternative means of conducting redshift surveys is discussed. Results in the directions of the Bootes and Coma voids show certain differences. In Bootes approximately ten objects have been identified within the void, but the Coma void appears empty at the same luminosities. The Coma void shows little evidence of having a bubble-like structure; it appears more spongelike. There is a large void behind the Coma/A1367 supercluster that is probably related to the Bootes void.

Coaxial Snowplow Discharge

The development of a coaxial plasma discharge in an initially uniform gas filling has been studied experimentally and theoretically. In the experiment, the usual outer coaxial electrode was replaced by a current return at the rear of the system, permitting unobstructed access to the discharge for the diagnostics. These diagnostics were image converter photography, magnetic probes, and holographic interferometry. The theory consists of two parts: two-dimensional (axisymmetric) time-dependent fluid computations and a supplementary analytic model, both of which assume that the vacuum magnetic field and the plasma are separated by a sharp interface; the experiments and computations are in good agreement on all gross features of the discharge leading up to the formation of a plasma focus and bubblelike structure in the shock front at the outer end of this focus.