Physical Parameters of a Reactor-Stellarator with Small Ripples of the Helical Magnetic Field

The paper describes the calculation data on the physical parameters of a reactor-stellarator, where the nonuniformities of the helical field are smaller than the toroidal magnetic field nonuniformities: ε_h < ε_t. Unlike the previous studies, where the ion-component transport coefficients had the collision frequency dependence proportional to ν^1/2, this being equivalent to the ε_h > ε_t case, in the present calculations, these coefficients were assumed to be in proportion to the first power of the collision frequency, D_i ∝ ν for ν_eff < 2ω_E, and to D_i ∝ ν^?1 for the inverse inequality. Here, ω_E is the rotation frequency of plasma in the radial electric field. As before, the plasma electrons corresponded to the mode of D_e ∝ ν^?1. As initial parameters for numerical calculations, a reactor with R = 8 m, r_p = 2 m, and B₀ = 5 Т was taken. A numerical code was used to solve the set of equations that describes the plasma space?time behavior in the reactor-stellarator under the conditions of equal diffusion fluxes. The start of reactor operation in the mode of thermonuclear burning was provided by heating sources with a power of several tens of megawatts. Steady-state operating conditions of a self-sustained thermonuclear reaction were attained by maintaining the plasma density through DT fuel pellet injection into the plasma.     

Exocyst Complex Member EXOC5 Is Required for Survival of Hair Cells and Spiral Ganglion Neurons and Maintenance of Hearing

The exocyst, an octameric protein complex consisting of Exoc1 through Exoc8, was first determined to regulate exocytosis by targeting vesicles to the plasma membrane in yeast to mice. In addition to this fundamental role, the exocyst complex has been implicated in other cellular processes. In this study, we investigated the role of the exocyst in cochlear development and hearing by targeting EXOC5, a central exocyst component. Deleting Exoc5 in the otic epithelium with widely used Cre lines resulted in early lethality. Thus, we generated two different inner ear-specific Exoc5 knockout models by crossing Gfi1^Cre mice with Exoc5^f/f mice for hair cell-specific deletion (Gfi1^Cre/+;Exoc5^f/f) and by in utero delivery of rAAV-iCre into the otocyst of embryonic day 12.5 for deletion throughout the otic epithelium (rAAV2/1-iCre;Exoc5^f/f). Gfi1^Cre/+;Exoc5^f/f mice showed relatively normal hair cell morphology until postnatal day 20, after which hair cells underwent apoptosis accompanied by disorganization of stereociliary bundles, resulting in progressive hearing loss. rAAV2/1-iCre;Exoc5^f/f mice exhibited abnormal neurite morphology, followed by apoptotic degeneration of spiral ganglion neurons (SGNs) and hair cells, which led to profound and early-onset hearing loss. These results demonstrate that Exoc5 is essential for the normal development and survival of cochlear hair cells and SGNs, as well as the functional maintenance of hearing.     

<Emphasis Type="Italic">l</Emphasis>=1 diocotron instability of single charged plasmas

The linear stability analysis of the l=1 diocotron perturbations in a low density single charged plasma confined in a cylindrical Penning trap is critically revisited. Particular attention is devoted to the instability due to the presence of one or more stationary points in the radial profile of the azimuthal rotation frequency. The asymptotic analysis of Smith and Rosenbluth for the case of a single-bounded plasma column (algebraic instability proportional to t^1/2) is generalized in a few respects. In particular, the existence of unperturbed density profiles that give rise to l=1 algebraic instabilities growing with time proportionally to t^1?1/m, m≥ 3 being the order of a stationary point in the rotation frequency profile, and even proportionally to t, is pointed out. It is also shown that smoothing the density jumps of a multistep density profile can convert algebraically growing perturbations into exponentially decaying modes. The relevant damping rates are computed. The asymptotic analysis (t → ∞) of the fundamental diocotron perturbations is then generalized to the case of a cylindrical Penning trap with an additional coaxial inner conductor. It is shown that the algebraic instability found in the case of a single-bounded plasma column becomes exponential at longer times. The relevant linear growth rate is computed by a suitable inverse Laplace transform (contour integral in the complex plane). In the particular case of an uncharged inner conductor of radius a, the growth rate is shown to scale as a^4/3 for a → 0. The theoretical results are compared with the numerical solution of the linearized two-dimensional drift Poisson equations.     

Effect of genetic and coexisting polymorphisms on platelet response to clopidogrel in Chinese Han patients with acute coronary syndrome

Polymorphisms of CYP2C19 are associated with platelet response to clopidogrel. This study was conducted to evaluate the contribution of the previously identified polymorphisms to the response of clopidogrel in a cohort of Chinese Han patients. A total of 222 acute coronary syndrome patients undergoing percutaneous coronary intervention treated with clopidogrel were enrolled from September 2012 to June 2013. Residual platelet aggregations for all patients were measured by the VerifyNow P2Y12 system. Sixteen single-nucleotide polymorphisms among nine genes were genotyped including CYP2C19, ABCB1 and PON1. In this study, CYP2C19*2 and CYP2C19*17 were strongly associated with higher platelet aggregation and lower platelet aggregation to clopidogrel treatment, respectively (P<0.001). Patients with CYP2C19*2 allele had a higher risk of high on-treatment platelet reactivity than non carriers (adjusted OR, 5.434; 95% CI, 1.918–15.399, P=0.01). The coexistence of CYP2B6*9 (rs8192719) and P2Y12 (rs2046934) and the coexistence of CYP2B6*1B (rs7254579) and P2Y12 (rs2046934) were also associated with poor response to clopidogrel. No significant relation of CYP2C19*3 and other polymorphisms to the platelet aggregation was found. In conclusion, CYP2C19*2, CYP2C19*17 coexistence of CYP2B6*9 (rs8192719) and P2Y12 (rs2046934) and coexistence of CYP2B6*1B (rs7254579) and P2Y12 (rs2046934) were identified to be associated with response to clopidogrel treatment in Chinese Han patients.     

Formation of a Z-pinch during electromagnetic compression of a nonquasineutral current filament

A study is made of the structure of a relativistic current filament with the azimuthal magnetic field B_θ in the range 4πn _e m _e c²?B _θ ² 4πn _i m _i c², when the plasma quasineutrality near the filament axis is violated and a narrow peak in electron density is formed there. The ion dynamics in a strong radial electric field of the filament on time scales of about several inverse ion plasma frequencies ω _pi ^?1 is investigated. The initial ion pressure prevents the ion plasma component from compression to infinitely high densities under the action of the electric field and leads to the formation of a dense hot plasma core near the axis of the Z-pinch on time scales of about a dozen ω _pi ^?1 . The compression of the ion component in the axial region gives rise to a collisionless “unloading” shock wave that propagates away from the axis and is accompanied by the vanishing of the radial ion velocity behind the shock front, the accumulation of positive charge near the axis, and the formation of a steady-state ion density profile. It is shown theoretically that ion-ion dissipation manifests itself as the destruction of the hot core of the formed Z-pinch on picosecond time scales. This may serve to explain the explosions of “hot points” in a current-carrying plasma.     

Inactivation of bone morphogenetic protein 1 (<Emphasis Type="Italic">Bmp1</Emphasis>) and tolloid-like 1 (<Emphasis Type="Italic">Tll1</Emphasis>) in cells expressing type I collagen leads to dental and periodontal defects in mice

Bone morphogenetic protein 1 (BMP1) and tolloid-like 1 (TLL1) belong to the BMP1/tolloid-like proteinase family, which cleaves secretory proteins. The constitutive deletion of the Bmp1 or Tll1 genes causes perinatal or embryonic lethality in mice. In this study, we first studied the β-galactosidase activity in mice in which an IRES-lacZ-Neo cassette was inserted in the intron of either the Bmp1 or the Tll1 gene; the β-galactosidase activities were used to reflect the expression of endogenous Bmp1 and Tll1, respectively. Our X-gal staining results showed that the odontoblasts in the tooth and cells in the periodontal ligament express both Bmp1 and Tll1. We then created Bmp1 ^flox/flox and Tll1 ^flox/flox mice by removing the IRES-lacZ-Neo cassette. By breeding 2.3 kb Col1a1-Cre mice with the Bmp1 ^flox/flox and Tll1 ^flox/flox mice, we further generated Col1a1-Cre;Bmp1 ^flox/flox ;Tll1 ^flox/flox mice in which both Bmp1 and Tll1 were inactivated in the Type I collagen-expressing cells. We employed X-ray radiography, histology and immunohistochemistry approaches to characterize the Col1a1-Cre;Bmp1 ^flox/flox ;Tll1 ^flox/flox mice. Our results showed that the molars of the Col1a1-Cre;Bmp1 ^flox/flox ;Tll1 ^flox/flox mice had wider predentin, thinner dentin and larger pulp chambers than those of the normal controls. The dentinal tubules of the molars in the Col1a1-Cre;Bmp1 ^flox/flox ;Tll1 ^flox/flox mice appeared disorganized. The level of dentin sialophosphoprotein in the molars of the 6-week-old Col1a1-Cre;Bmp1 ^flox/flox ;Tll1 ^flox/flox mice was lower than in the normal controls. The periodontal ligaments of the Col1a1-Cre;Bmp1 ^flox/flox ;Tll1 ^flox/flox mice were disorganized and had less fibrillin-1. Our findings indicate that the proteinases encoded by Bmp1 and Tll1 genes play essential roles in the development and maintenance of mouse dentin and periodontal ligaments.     

Transition into the improved core confinement mode as a possible mechanism for additional electron heating observed in the lower hybrid current drive experiments at the FT-2 tokamak

In experiments on lower hybrid current drive (LHCD) carried out at the FT-2 tokamak, a substantial increase in the central electron temperature T _e (r = 0 cm) from 550 to 700 eV was observed. A complex simulation procedure is used to explain a fairly high LHCD efficiency and the observed additional heating, which can be attributed to a transition into the improved core confinement (ICC) mode. For numerical simulations, data obtained in experiments with deuterium plasma at 〈n _e 〉 = 1.6 × 10¹⁹ m^–3 were used. Simulations by the GRILL3D, FRTC, and ASTRA codes have shown that the increase in the density and central temperature is apparently caused by a significant suppression of heat transport in the electron component. The mechanism for transition into the improved confinement mode at r < 3 cm can be associated with the broadening of the plasma current channel due to the lower hybrid drive of the current carried by superthermal and runaway electrons. In this case, the magnetic shear s = (r/q)(dq/dr) in the axial region of the plasma column almost vanishes during the RF pulse. In this study, the effect of lower hybrid waves on the plasma parameters, resulting in a transition into the ICC mode, is considered. New experimental and calculated data are presented that evidence in favor of such a transition. Special attention is paid to the existence of a threshold for the transition into the ICC mode in deuterium plasma.     

Microwave electrode discharge in nitrogen: Structure and characteristics of the electrode region

The parameters of the electrode region of an electrode microwave discharge in nitrogen are studied by emission spectroscopy. The radial and axial distributions of the intensities of the bands of the second (N₂(C ³Π _u → B ³Π _g )) and first (N₂(B ³Π _g → A ³Σ _u ⁺ )) positive systems of molecular nitrogen and the first negative system of nitrogen ions (N ₂ ⁺ (B ²Σ _u ⁺ → X ²Σ _g ⁺ )), the radial profiles of the electric field E and the electron density N _e , and the absolute populations of the vibrational levels v _C = 0–4 of the C ³Π _u excited state of N₂ and the vibrational level v _Bi = 0 of the B ²Σ _u ⁺ excited state of a molecular nitrogen ion are determined. The population temperature of the first vibrational level T _V of the ground electronic state X ¹Σ _g ⁺ of N₂ and the excitation temperature T _C of the C ³Π _u state in the electrode region of the discharge are measured. The radius of the spherical region and the spatially integrated plasma emission spectra are studied as functions of the incident microwave power and gas pressure. A method for determining the electron density and the microwave field strength from the plasma emission characteristics is described in detail.     

Plasma diagnostics from intensities of resonance line series of He-like ions

The possibility of using the relative intensities of the 1snp ¹P₁–1s ^{2 1}S0 transitions with n = 3–6 in He-like multicharged ions to diagnose plasma in a nonstationary ionization state is considered. The calculations performed for F VIII ions show that, at electron temperatures of T _e = 10–100 eV, the intensity ratios are sensitive to the plasma electron density in the range of N _e = 10¹⁶–10²⁰ cm^–3. The universal calculated dependences can be used to diagnose various kinds of recombining or ionizing plasmas containing such ions.     

High plasma adenosine levels in overweight/obese pregnant women

We aim to investigate whether overweight/obese pregnant women have elevated plasma levels of adenosine associated with increased consumption of high-calorie food. Sixty women were included. They were divided into lean (n = 23 and n = 12) or overweight/obese (n = 7 and n = 18) non-pregnant and pregnant women, respectively. Clinical records and maternal blood samples were collected after informed consent. A self-reported dietary questionnaire was also completed. Plasma adenosine levels were determined with high-performance liquid chromatography. Biochemical parameters, including glucose, total protein, and lipid profile, were determined using standard colorimetric assays. Adenosine levels were higher in pregnant women than in non-pregnant women (18.7 ± 1.6 vs 10.8 ± 1.3 nM/μg protein, respectively, p < 0.0001). Overweight/obese pregnant women (21.9 ± 2.5 nM/μg protein) exhibited higher adenosine levels than lean pregnant (14.5 ± 1.0 nM/μg protein, p = 0.04) or non-pregnant women (11.7 ± 1.5 nM/μg protein, p = 0.0005). Also, pregnant women with elevated weight gain exhibited higher (26.2 ± 3.7 nM/μg protein) adenosine levels than those with adequate weight gain (14.9 ± 1.4 nM/μg protein, p = 0.03). These differences were not statistically significant compared with those of pregnant women with reduced weight gain (17.4 ± 2.1 nM/μg protein, p = 0.053). Body mass index and adenosine only in pregnant women were positively correlated (r = 0.39, p = 0.02). While, polyunsaturated fatty acid (PUFA) consumption was negatively correlated with plasma adenosine levels only in non-pregnant women (r = ?0.33, p = 0.03). Pregnancy is associated with high plasma adenosine levels, which are further elevated in pregnant women who are overweight/obese. High PUFA intake might reduce plasma adenosine levels in non-pregnant women.     

Simulations of the Ion Current to a Probe in Plasma with Allowance for Ionization and Ion–Neutral Collisions: II. Cylindrical Probe

The ion current to a cylindrical probe is considered with allowance for volume ionization, ion–neutral collisions, and the ion orbital moment. A model based on the molecular dynamics method and applicable in a wide range of plasma parameters (r_p/λ_D= 0.01–100, r_i/λ_D= 0.002–200, ν_i/ω_0i= 0.01–0.05, and T_i/T_e = 0?0.01) is proposed A convenient representation of the dependence of the relative ion current density on the Langmuir coefficient β² and a technique for determining the plasma density from simulation results are offered.     

Anomalous pinch in the T-11M tokamak in an enhanced-collisionality regime

The formation of a peaked bell-shaped profile of the electron density n _e (r) in the T-11M tokamak (B _t=1 T, R/a = 0.7/0.2 m, I _p = 100 kA, t _shot ≤ 300 ms, Li and C limiters) was observed in Li experiments carried out in the near-plateau collisionality regime (the collisionality parameter at one-half of the minor radius was v* ≥ 0.5) under the conditions of low hydrogen recycling and intense hydrogen influx from the plasma edge. It is well known that peaked n _e (r) profiles are observed in collisionless regimes at v* values as low as 10^?1–10^?2 or in impurity-contaminated discharges, in which this effect can be attributed to the impurity accumulation on the plasma column axis. Moreover, a bell-shaped n _e (r) profile in discharges with low n _e can result from the ionization of hydrogen atoms at the column axis, where they arrive from the plasma edge due to cascade charge-exchange. In quasi-steady lithium discharges in T-11M, however, peaked n _e (r) profiles were observed at a relatively high central electron density n _e (0) and relatively high collision frequency, such that the influence of impurities on the n _e (r) profile could be ignored (Z _eff = 1.1±0.1). To explain this effect, one has to assume that the pinching of hydrogen ions in T-11M is anomalous. The lower estimate of the observed pinch velocity is 4 ± 1 m/s, which is three to five times higher than the velocity of the neoclassical (Ware) pinch, characteristic of these conditions. The work is devoted to the experimental study of this effect.     

Interaction of near-IR laser radiation with plasma of a continuous optical discharge

The interaction of 1.07-μm laser radiation with plasma of a continuous optical discharge (COD) in xenon and argon at a pressure of p = 3–25 bar and temperature of T = 15 kK has been studied. The threshold power required to sustain COD is found to decrease with increasing gas pressure to P _t < 30 W in xenon at p > 20 bar and to P _t < 350 W in argon at p > 15 bar. This effect is explained by an increase in the coefficient of laser radiation absorption to 20?25 cm^–1 in Xe and 1?2 cm^–1 in Ar due to electronic transitions between the broadened excited atomic levels. The COD characteristics also depend on the laser beam refraction in plasma. This effect can be partially compensated by a tighter focusing of the laser beam. COD is applied as a broadband light source with a high spectral brightness.     

Prototrophic Regulatory Mutants of Adenylosuccinate Synthetase in Yeast

MUTANTS of the genes ade12 and ade13 in Saccharomyces cerevisiae require adenine, which suggests that they are defective in the conversion of inosine monophosphate (IMP) to adenosine monophosphate (AMP). Two enzymes are required for this conversion: adenylosuccinate lyase and adenylosuccinate synthetase. The former has been shown to be absent in mutants of ade13 (ref. 1) so that one can infer that ade12 specifies the latter. Mutants of ade12 have been isolated on the basis of an adenine insensitive pigment accumulation by strains carrying ade1 or ade2 (refs. 1 and 2). They seem to synthesize purines constitutively and excrete hypoxanthine¹. These observations suggest that in addition to its catalytic function adenylosuccinate synthetase has an important function in the regulation of purine synthesis.     

Laboratory modeling of nonstationary processes in space cyclotron masers: First results and prospects

Results are presented from laboratory modeling of the dynamics of space cyclotron masers. A selfoscillatory mode of cyclotron instability in the nonequilibrium plasma of an ECR discharge in a magnetic mirror trap is found. The plasma comprises two electron populations: the background population with a density of N _e ～ 10¹³–10¹⁴ cm^?3 and temperature of T _e ≈ 300 eV and the energetic population with a density of N _e ～ 10¹⁰ cm^?3 and temperature of T _e ≈ 10 keV. Quasi-periodic pulsed precipitation of energetic electrons from the trap, accompanied by microwave bursts at frequencies below the electron gyrofrequency in the center of the trap, is detected. The study of the microwave plasma emission and the energetic electrons precipitated from the trap shows that the precipitation is related to the excitation of whistler-mode waves propagating nearly parallel to the trap axis. The observed instability has much in common with phenomena in space magnetic traps, such as radiation belts of magnetized planets and solar coronal loops. The experimental results demonstrate the opportunity of laboratory modeling of space cyclotron masers. The main tasks and possibilities of such modeling are discussed.     

On the minimum electron transport coefficients in tokamaks in the range of low collision frequencies

There are two close empirical scalings, namely, the T-11 and neo-Alcator ones, that provide correct estimates for the energy confinement time in tokamaks in ohmic heating regimes in the linear part of the dependence τ _E (\(\bar n_e \)) in the range of low values of \(\bar n_e \) and 〈ν _e ^* 〉 ≤ 1. The similar character of electron energy confinement in this range, which expands with increasing magnetic field B ₀, has stimulated the search for dimensionless parameters and simple physical models that would explain the experimentally observed dependences χ _e ～ 1/n _e and τ _Ee ～ \(\bar n_e \). In 1987, T. Okhawa showed that the experimental data were satisfactorily described by the formula χ_e⊥ = (c ²/ω _pe ² )ν _e /qR, in deriving of which the random spatial leap along the radius r on the electron trajectory was assumed to be the same as that in the coefficient of the poloidal field diffusion, while the repetition rate of these leaps was assumed to be ν _e /qR. In 2004, J. Callen took into account the decrease in the fraction of transient electrons with increasing toroidal ratio ? = r/R and corrected the coefficient c ²/ω _pe ² in Okhawa equation by the factor σ _‖ ^Sp /σ _‖ ^neo . If one takes into account this correction and assumes that the frequency of the stochastic process is equal to the reciprocal of the half-period of rotation of a trapped electron along its banana trajectory, then the resulting expression for χ_e⊥ will coincide with the T-11 scaling: χ _e ^an ∞ ?^1.75(T _e /A _i )^0.5/(n _e qR) at A i = 1. If the same stochastic process also involves ions, it may result in the opening of the orbit of a trapped ion at the distance ～(c/ω _pe )(m _i /m _e )^1/4. In this case, the calculated coefficient of electron and ion diffusion D is close to D ^an ≈ χ _e ^an /2.     

Analysis of compound heterozygotes reveals that the mouse floxed <Emphasis Type="Italic">Pax6</Emphasis><Superscript><Emphasis Type="Italic">tm1Ued</Emphasis></Superscript> allele produces abnormal eye phenotypes

Analysis of abnormal phenotypes produced by different types of mutations has been crucial for our understanding of gene function. Some floxed alleles that retain a neomycin-resistance selection cassette (neo cassette) are not equivalent to wild-type alleles and provide useful experimental resources. Pax6 is an important developmental gene and the aim of this study was to determine whether the floxed Pax6 ^tm1Ued (Pax6 ^fl ) allele, which has a retained neo cassette, produced any abnormal eye phenotypes that would imply that it differs from the wild-type allele. Homozygous Pax6 ^fl/fl and heterozygous Pax6 ^fl/+ mice had no overt qualitative eye abnormalities but morphometric analysis showed that Pax6 ^fl/fl corneas tended be thicker and smaller in diameter. To aid identification of weak effects, we produced compound heterozygotes with the Pax6 ^Sey-Neu (Pax6 ^?) null allele. Pax6 ^fl/? compound heterozygotes had more severe eye abnormalities than Pax6 ^+/? heterozygotes, implying that Pax6 ^fl differs from the wild-type Pax6 ⁺ allele. Immunohistochemistry showed that the Pax6 ^fl/? corneal epithelium was positive for keratin 19 and negative for keratin 12, indicating that it was abnormally differentiated. This Pax6 ^fl allele provides a useful addition to the existing Pax6 allelic series and this study demonstrates the utility of using compound heterozygotes with null alleles to unmask cryptic effects of floxed alleles.     

Structural organization characteristics of the <Emphasis Type="Italic">DIP1</Emphasis> gene in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> strains mutant for the <Emphasis Type="Italic">flamenco</Emphasis> gene

Molecular cloning of the DIP1 gene located in the 20A4-5 region has been performed from the following strains with the flamenco phenotype: flam ^SS (SS) and flam ^MS (MS) characterized by a high transposition rate of retrotransposon gypsy (mdg4), flam ^{py + (P)} carrying the insertion of a construction based on the P element into the region of the flamenco gene, and flamenco ⁺. The results of restriction analysis and sequencing cloned DNA fragments has shown that strains flam ^SS , flam ^MS considerably differ from flam ^{py + (P)}, and flamenco ⁺ in the structure of DIP1. Strains flam ^SS and flam ^MS have no DraI restriction site at position 1765 in the coding region of the gene, specifically, in the domain determining the signal of the nuclear localization of the DIP1 protein. This mutation has been found to consist in a nucleotide substitution in the recognition site of DraI restriction endonuclease, which is transformed from TTTAAA into TTTAAG and, hence, is not recognized by the enzyme. This substitution changes codon AAA into AAG and is translationally insignificant, because both triplets encode the same amino acid, lysine. The DIP1 gene of strains flam ^SS and flam ^MS has been found to contain a 182-bp insertion denoted IdSS (insertion in DIP1 strain SS); it is located in the second intron of the gene. The IdSS sequence is part of the open reading frame encoding the putative transposase of the mobile genetic element HB1 belonging to the Tc1/mariner family. This insertion is presumed to disturb the conformations of DNA and the chromosome, in particular, by forming loops, which alters the expression of DIP1 and, probably, neighboring genes. In strains flamenco ⁺ and flam ^{py + (P)}, the IdSS insertion within the HB1 sequence is deleted. The deletion encompasses five C-terminal amino acid residues of the conserved domain and the entire C-terminal region of the putative HB1 transposase. The obtained data suggest that DIP1 is involved in the control of gypsy transpositions either directly or through interaction with other elements of the genome.