Investigation of the single neutron exposure model for the s-process: the primary nature of the neutron source

The primary nature of the ¹³C neutron source is very significant for the studies of the s -process nucleosynthesis. In this paper we present an attempt to fit the element abundances observed in 16 s -rich stars using parametric model of the single neutron exposure. The calculated results indicate that almost all s -elements were made in a single neutron exposure for nine sample stars. Although a large spread of neutron exposure is obtained, the maximum value of the neutron exposure will reach about 7.0 mbarn⁻¹, which is close to the theoretical predictions by the asymptotic giant branch (AGB) model. The calculated result is a significant evidence for the primary nature of the neutron source. Combining the result obtained in this work and the neutron exposure–initial mass relations, a large spread of neutron exposure can be explained by the different initial stellar mass and their time evolution. The possibility that the rotationally induced mixing process can lead to a spread of the neutron exposure in AGB stars is also existent.     

Is there a Nuclear Reactor at the Center of the Earth?

In this paper we discuss the Herndon hypothesis that a nuclear reactor is operating at the center of the Earth. Recent experimental evidence shows that some uranium can have partitioned into the core. There is no viable mechanism for the small amount of uranium that is dissolved in the molten metal to crystallize as a separate uranium phase (uranium metal or uranium sulfide) and migrate to the center of the core. There is no need for an extra heat source, as the total heat leaving the core can be easily provided by “classical” heat sources, which are also more than adequate to maintain the Earth’s magnetic field. It is unlikely that nuclear georeactors (fast breeder reactors) are operating at the Earth’s center.     

Rings of radio continuum,Co, Hα and magnetic fields in galaxies

Abstract

Observations are reviewed that indicate the existence of rotating rings in a number of galaxies that possess poloidal magnetic fields in their nuclear regions, including our own Galaxy. Jets from these, possibly aligned with the poloidal field, may also be present. The role of these rings in dynamo processes is briefly discussed.     

A semi-empirical method for predicting hydrological drought magnitudes in the Canadian prairies

Abstract

A hydrological drought magnitude (M _T ) expressed in standardized terms is predicted on annual, monthly and weekly time scales for a sampling period of T years in streamflow data from the Canadian prairies. The drought episodes are considered to follow the Poisson law of probability and, when coupled with the gamma probability distribution function (pdf) of drought magnitude (M) in the extreme number theorem, culminate in a relationship capable of evaluating the expected value, E(M _T ). The parameters of the underlying pdf of M are determined based on the assumption that the drought intensity follows a truncated normal pdf. The E(M _T ) can be evaluated using only standard deviation (σ), lag-1 autocorrelation (ρ) of the standardized hydrological index (SHI) sequence, and a weighting parameter Φ (ranging from 0 to 1) to account for the extreme drought duration (L _T ), as well as the mean drought duration (L_m ), in a characteristic drought length (L_c ). The SHI is treated as standard normal variate, equivalent to the commonly-used standardized precipitation index. A closed-form relationship can be used for the estimation of first-order conditional probabilities, which can also be estimated from historical streamflow records. For all rivers, at the annual time scale, the value of Φ was found equal to 0.5, but it tends to vary (in the range 0 to 1) from river to river at monthly and weekly time scales. However, for a particular river, the Φ value was nearly constant at monthly and weekly time scales. The proposed method estimates E(M _T ) satisfactorily comparable to the observed counterpart. At the annual time scale, the assumption of a normal pdf for drought magnitude tends to yield results in close proximity to that of a gamma pdf. The M _T , when transformed into deficit-volume, can form a basis for designing water storage facilities and for planning water management strategies during drought periods.

Editor D. Koutsoyiannis; Associate editor C. Onof

Citation Sharma, T.C. and Panu, U.S., 2013. A semi-empirical method for predicting hydrological drought magnitudes in the Canadian prairies. Hydrological Sciences Journal, 58 (3), 549–569.     

地震震级误差对bem>值的影响

地震震级通常因地震目录的不同而不同,由此所计算的b值也不尽一致．当震级的一致性很差时,b值的误差也很大．基于这一原因,通过假定视震级（目录震级）围绕着真震级的正态分布,利用频率 震级关系式（古登堡 里克特公式）求真震级下的b值．根据这一正态分布,对属于同一真震级的地震次数进行计算,从而获得b值精度大大优于用视震级所计算的相应值．为了显示本方法的优点,我们用通常意义下的计算方法和本文所介绍的方法对中国３个不同构造区域进行计算和比较;另外,考虑到大震震级饱和对计算的影响（掉头现象）,我们将数据从M＝7.0处分成两部分．结果表明,用本方法计算的结果优于利用视震级所得到的结      

用数字记录资料测定腾冲火山区的微震参数

利用数字化地震记录资料 ,测定了腾冲火山及其周围地区的地震基本参数 ,结果表明 ,腾冲火山区内的地震活动以微震为主 ,震级多数在 1～ 2 5级之间 ,且地震活动频度低 ;而周围地区的构造地震活动频繁 ,且强度大。在腾冲火山区内地震活动的空间分布也表现出明显的非均匀性 ,以腾冲县城以北 (即 2 5°N以北 )的火山区内地震活动少 ,而县城以南的火山区 (热海热田地区 )微震活动相对多 ,且以微震群的形式发生。根据C F Richter震级标度测定的震级结果 ,火山区的微震活动事件可达 0 4震级单位。震源深度的定位结果给出 ,火山地区的微震震源深度绝大多数在 1～ 6km的范围 ,属于典型的浅源地震 ,而周围地区构造地震的震源深度多多数大于 2 0km。腾冲火山区的微震活动分布、地震强度、及震源深度特征所表现的现象可能与地下岩浆体活动相关 ,显示了与火山热物质孕震机理有关的明显特征。     

1999年11月1日大同-阳高Ms5.4级地震预报纪实

１９９９年１１月１日在山西省大同－阳高地区发生了一次Ｍｓ５．４级地震。这次地震前笔者采用测震学方法对华北地震活动性进行分析研究,结果发现华北缺震曲线,华北地震曲线、频度曲线都出现低值异常。邢台震区月频度曲线６月份小震活动增强。北京地区缺震曲线、频度曲线都出身低值异常。１９９９年６月份在晋冀蒙三省交界地区的大同附近小震活动丛集、频度与蠕变加速,并于９月１２日发生了左云ＭＬ４．７级信号震。据此,笔者在     

Geological and Historical Investigation of the 1650 Mt. Columbo (Thera Island) Eruption and Tsunami, Aegean Sea, Greece

This paper reviews geological andhistorical evidence for the eruption and tsunamireported to have occurred in 1650 in the areaof Mt. Columbo, Thera Island, Greece. The tsunami isbelieved to have been generated as a consequence ofthe eruption of Mt. Columbo 6.5 km NE of Thera Island.Historical documents state that the tsunami flooded upto 2 miles inland and destroyed many engineeredstructures. We present lithostratigraphic evidencefrom one abandoned trench and two trench excavationsclose to sea level in the villages of Kamari andPerissa respectively, which lie well within thereported inundation zone of the tsunami. The resultspresented show that no marine- (tsunami) depositedsediments are preserved at these locations.Alternative hypotheses of discontinuous sedimentdeposition and over estimation of the event magnitudeare considered to explain the observations presentedhere. The data may have important implications for thedevelopment of hazard zone maps, risk assessment,vulnerability reduction and for emergency managementofficials.     

Seismic Hazard of Honduras

In this paper we have described the proceduresused, input data applied and results achieved in ourefforts to develop seismic hazard maps of Honduras.The probabilistic methodology of Cornell is employed.Numerical calculations were carried out by making useof the computer code SEISRISK III. To examine theimpact of uncertainties in seismic and structuralcharacteristics, the logic tree formalism has beenused. We compiled a de-clustered earthquake cataloguefor the region comprising 1919 earthquakes occurringduring the period from 1963 to 1997. Unified momentmagnitudes were introduced. Definition of aseismotectonic model of the whole region under review,based on geologic, tectonic and seismic information,led to the definition of seven seismogenetic zones forwhich seismic characteristics were determined. Fourdifferent attenuation models were considered. Resultsare expressed in a series of maps of expected PGA for60% and 90% probabilities of nonexceedence in a50-year interval which corresponds to return periodsof 100 and 475 years, respectively. The highest PGAvalues of about 0.4g (90% probability ofnon-exceedence) are expected along the borders withGuatemala and El Salvador.