990 resultados para 170-1041
Resumo:
We assayed allelic variation at 19 nuclear-encoded microsatellites among 1622 Gulf red snapper (Lutjanus campechanus) sampled from the 1995 and 1997 cohorts at each of three offshore localities in the northern Gulf of Mexico (Gulf). Localities represented western, central, and eastern subregions within the northern Gulf. Number of alleles per microsatellite per sample ranged from four to 23, and gene diversity ranged from 0.170 to 0.917. Tests of conformity to Hardy-Weinberg equilibrium expectations and of genotypic equilibrium between pairs of micro-satellites were generally nonsignificant following Bonferroni correction. Significant genic or genotypic heterogeneity (or both) among samples was detected at four microsatellites and over all microsatellites. Levels of divergence among samples were low (FST ≤0.001). Pairwise exact tests revealed that six of seven “significant” comparisons involved temporal rather than spatial heterogeneity. Contemporaneous or variance effective size (NeV) was estimated from the temporal variance in allele frequencies by using a maximum-likelihood method. Estimates of NeV ranged between 1098 and >75,000 and differed significantly among localities; the NeV estimate for the sample from the northcentral Gulf was >60 times as large as the estimates for the other two localities. The differences in variance effective size could ref lect differences in number of individuals successfully reproducing, differences in patterns and intensity of immigration, or both, and are consistent with the hypothesis, supported by life-history data, that different “demographic stocks” of red snapper are found in the northern Gulf. Estimates of NeV for red snapper in the northern Gulf were at least three orders of magnitude lower than current estimates of census size (N). The ratio of effective to census size (Ne/N) is far below that expected in an ideal population and may reflect high variance in individual reproductive success, high temporal and spatial variance in productivity among subregions or a combination of the two.
Resumo:
The yrast sequence of the neutron-rich dysprosium isotope Dy168 has been studied using multinucleon transfer reactions following collisions between a 460-MeV Se82 beam and an Er170 target. The reaction products were identified using the PRISMA magnetic spectrometer and the γ rays detected using the CLARA HPGe-detector array. The 2+ and 4+ members of the previously measured ground-state rotational band of Dy168 have been confirmed and the yrast band extended up to 10+. A tentative candidate for the 4+→2+ transition in Dy170 was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed. © 2010 The American Physical Society.
Resumo:
This paper reports laboratory measurements of the spectrum of highly ionized sulfur. The spectrum of S Ⅸ–S ⅩⅢ has been observed in the wavelength range 170–500 Å. A total of 54 lines have been measured. Forty-two of them have been classified as 2s22pk–2s2pk+1and 2s2pk–2pk+1 transitions. Twelve other lines have been ascribed to 2s–2p,4p–5s,5p–6s,5d–6p, and 6p–8d transitions. These spectral lines have been identified, among which 22 are new and accurately measured. The analysis of the spectra was based on a comparison with other experimental results and calculated values.
Resumo:
在 16 6MeV的束流能量下 ,利用重离子熔合蒸发反应14 2 Nd(3 2 S ,1p3nγ) 170 Re布居了170 Re的高自旋激发态 .用 12套带BGO反康普顿抑制的高纯锗探测器阵列进行了在束X -γ和γ -γ符合测量 .基于对实验测量结果及周围邻近核已知信息的综合分析 ,首次建立了双奇核170 Re的转动带能级纲图 .根据实验提取出的准粒子顺排、旋称劈裂等结构特征和Re双奇核同位素带结构系统学知识的比较分析 ,指出该带的准粒子组态是πh11 2 υi13 2 .
Resumo:
通过重离子熔合蒸发反应142Nd(32S,1p3nγ)170Re布居了缺中子双奇核170Re的高自旋激发态,识别出了该核的一条转动带并建议了其组态为πh1/2 νi13/2。基于对同中子素能级系统性、旋称反转系统性、带内B(M1)/B(E2)、准粒子Routhians、动力学转动惯量和Total Routhian Surface(TRS)等带结构特征的详细分析和讨论,进一步确认了对A=170核区目前最缺中子双奇核高自旋转动带组态、宇称和自旋值的指定。
Resumo:
Efforts have been made in our group to study the band structure of odd-odd nuclei in the A similar to 170 mass region. We aimed at providing new data of high-spin states and searching for the low-spin signature inversion in the 2-qp bands built on the pi h(9/2) circle times nu i(13/2) and pi i(13/2)circle times nu i(13/2) configurations. In this talk, main results of our work will be summarized, and some systematic features of signature inversion discussed. The spin and parity assignments for the pi i(13/2) circle times nu i(13/2) band in (184)An could be regarded as firm providing a good example for systematic and theoretical investigations.
Resumo:
本文概述了 A > 170 质量区重丰中子同位素研究的主要工作和意义;介绍了 A > 170 重丰中子同位素合成、分离和鉴别方法;详细论述了激光离子源的原理、设计及其同传统离子源相比所具有的优越性;在文章结尾,设计了一个物理实验,实验目的在于:1)寻找 ~(181)Yb新核素;2)揭示天体物理学中~(180m)Ta 的产生问题。我们对反应截面进行了分析,并对产额进行了估计,证明了此实验设计的合理性,进而说明了带激光离子源的同位素分离器适用于产生截面很低的新核素和衰变研究。本文重点讨论了激光离子源的各方面问题:介绍了激光多步共振电离原理和激光离子源原理;具体分析了热毛细管式激光离子源元素选择性的产生及其影响的因素;讨论了在设计、加工过程中的具体问题;描述了所使用的激光技术;通过在线实验验证了热毛细管式激光离子源的元素选择性和分离效率。
Resumo:
本文概述了关于远离β稳定线研究的进展;分析了A>170新丰中子同位素研究的主要工作和意义。介绍了A>170新丰中子同位素合成、分离和鉴别方法,阐述了在A>170区新核素合成研究中,传统的合成、分离和鉴别手段要比新兴的次级束装置方法更具有优越性,产额中前者有103—104倍的优势,能获得剩余激发能较低的产物,及能进行较长寿命(大于1秒)核研究;激光离子源在线同位素分离器的使用,使之具有很好的元素选择性和质量分辨本领,从而可以使用低本底、高效率的探测方法。 本文侧重介绍了激光离子源在线同位素分离器的研究和使用中的一系列实验和结果:1)激光离子源的研制,得到了501-10000的元素选择性;2)进行了核反应产物从靶中快速释放的研究;3)完成了激光离子源在线同位素分离器的离线实验;4)低本底、高效率的ΔE—ΔEβ探测器的制作及其性能的初步研究;5)实现了激光离子源在线同位素分离器的首次在线实验,获得了良好的元素选择性和一定的分离效率。 最后,对进一步的在线实验和激光的应用做了介绍。
Resumo:
The gram-negative bacterium Pseudomonas cichorii 170, isolated from soil that was repeatedly treated with the nematocide 1,3-dichloropropene, could utilize low concentrations of 1,3-dichloropropene as a sole carbon and energy source, Strain 170 was also able to grow on 3-chloroallyl alcohol, 3-chloroacrylic acid, and several 1-halo-n-alkanes. This organism produced at least three different dehalogenases: a hydrolytic haloalkane dehalogenase specific for haloalkanes and two 3-chloroacrylic acid dehalogenases, one specific for cis-3-chloroacrylic acid and the other specific for trans-3-chloroacrylic acid. The haloalkane dehalogenase and the trans-3-chloroacrylic acid dehalogenase were expressed constitutively, whereas the cis-3-chloroacrylic acid dehalogenase was inducible, The presence of these enzymes indicates that 1,3-dichloropropene is hydrolyzed to 3-chloroallyl alcohol, which is oxidized in two steps to 3-chloroacrylic acid. The latter compound is then dehalogenated, probably forming malonic acid semialdehyde. The haloalkane dehalogenase gene, which is involved in the conversion of 1,3-dichloropropene to 3-chloroallyl alcohol, was cloned and sequenced, and this gene turned out to be identical to the previously studied dhaA gene of the gram-positive bacterium Rhodococcus rhodochrous NCIMB13063, Mutants resistant to the suicide substrate 1,2-dibromoethane lacked haloalkane dehalogenase activity and therefore could not utilize haloalkanes for growth. PCR analysis showed that these mutants had lost at least part of the dhaA gene.
Resumo:
Unfavorable work characteristics, such as low job control and too high or too low job demands, have been suggested to increase the likelihood of physical inactivity during leisure time, but this has not been verified in large-scale studies. The authors combined individual-level data from 14 European cohort studies (baseline years from 19851988 to 20062008) to examine the association between unfavorable work characteristics and leisure-time physical inactivity in a total of 170,162 employees (50 women; mean age, 43.5 years). Of these employees, 56,735 were reexamined after 29 years. In cross-sectional analyses, the odds for physical inactivity were 26 higher (odds ratio 1.26, 95 confidence interval: 1.15, 1.38) for employees with high-strain jobs (low control/high demands) and 21 higher (odds ratio 1.21, 95 confidence interval: 1.11, 1.31) for those with passive jobs (low control/low demands) compared with employees in low-strain jobs (high control/low demands). In prospective analyses restricted to physically active participants, the odds of becoming physically inactive during follow-up were 21 and 20 higher for those with high-strain (odds ratio 1.21, 95 confidence interval: 1.11, 1.32) and passive (odds ratio 1.20, 95 confidence interval: 1.11, 1.30) jobs at baseline. These data suggest that unfavorable work characteristics may have a spillover effect on leisure-time physical activity.