Radiative lifetimes of 7d, 8d <Superscript>1</Superscript>D<Subscript>2</Subscript> excited states of Hg I

Radiative lifetimes of 7d, 8d ¹ D ₂ excited states of Hg I are measured using pulsed two-photon excitation from the ground [Xe]5d ¹⁰6s ^{2 1} S ₀ mercury state, detecting the decay of the laser-induced fluorescence. The results are compared with theoretical values, obtained by means of a Hartree-Fock single configuration method, taking into account electron configuration interaction. The radiative lifetime value dependence on the effective principal quantum number for the nd ¹ D ₂ series is analyzed and compared with the quantum defect dependence. Received 25 February 2000 and Received in final form 26 July 2000     

Lifetime measurements in Gd II and Gd III using time-resolved laser spectroscopy

Natural radiative lifetimes of 20 levels (energy range between 29 000-35 000 cm^-1) in Gd II and 5 levels (energy range between 43 000-49 000 cm^-1) in Gd III have been measured using time-resolved laser-induced fluorescence in a laser-produced plasma. Received 17 July 2000 and Received in final form 13 October 2000     

Measurementof the transition probability in calcium

We have measured the ratio between the transition probabilities of two forbidden lines in Ca: the intercombination line at 657.3 nm and the E 2 line at 457.5 nm. The value we obtained for this ratio is (54.1±2.4). Combined with the most accurate value available in literature for the lifetime of the ³ P ₁ level, our measurement gives a value of (54.4±4.0) s^-1 for the ¹ S ₀ ↦ ¹ D ₂ transition probability, significantly more accurate than the previous determinations. Received 17 June 2002 / Received in final form 9 December 2002 Published online 4 March 2003     

On exhibiting inventory systems with Erlangian lifetimes under renewal demands

A continuous revies (s, S) inventory system with renewal demand in which one item is put into operation as an exhibiting piece is analyzed. The lifetime of any operating unit has Erlangian distribution, and on failure is replaced by another one from the stock and the failed item is disposed of. Replenishment of stock is instantaneous. The transient and stationary values of inventory level distribution and the mean reorder rate are obtained using the techniques of semi-regenerative processes. Decision rules for optimums andS that minimize the long-run expected cost rate are derived. The solution for a dual model with the distribution of lifetimes and inter-demand times interchanged is also given.     

条件Brown运动生命时的一个渐近估计

设Ｄ为Ｒｄ中的有界规则区域．本文绘出了一个Ｄ内条件Ｂｒｏｗｎ运动生命时的渐近估计其中Ｇ为Ｒｄ内满足的开集，为主持征值（关于Ｄｉｒｉｃｈｌｅｔ边值条件），μ是属于广义Ｋａｔｏ类的符号Ｒａｄｏｎ测度，Ａｔ是与μ相联系的Ｂｒｏｗｎ运动（Ｘｔ）ｔ≥０的有界变差连续的可加泛函，ｈ是关Ｄ内的正解。     

条件扩散过程的生命时与条件Gauge

本文给出了有界的Ｌｉｐｓｃｈｉｔｚ区域Ｄ内的条件扩散过程的生命时Ｔ＿Ｄ的一个渐近估计，由此给出了Ｇａｕｇｅ与条件Ｇａｕｇｅ为有穷或无穷的谱条件，并得出了Ｇａｕｇｅ定理与条件Ｇａｕｇｅ定理。     

Multivariate Hazard Rates under Random Censorship

The data consists of multivariate failure times under right random censorship. By the kernel smoothing technique, convolutions of cumulative multivariate hazard functions suggest estimators of the so-called multivariate hazard functions. We establish strong i.i.d. representations and uniform bounds of the remainder terms on some compact sets of the underlying space. Thus asymptotic normality and uniform consistency on such sets are obtained. The asymptotic mean squared error gives an optimal bandwidth by the plug-in method. Simulations assess the performance of our estimators.     

Inelastic interactions of protons and electrons with biologically relevant molecules

Ionization and fragmentation of water and uracil molecules was studied both by electron and proton impact. A special coincidence technique allows on an event by event basis the investigation of product ions formed upon the collision of protons with neutral molecules including the identification of the charge state of the projectile. This enables the characterization of the ionization processes occurring, i.e. direct ionization, single electron capture or double electron capture for 0, 1 or 2 electrons that are transferred from the target to the projectile, respectively. For uracil the fragmentation patterns obtained by electron and proton impact ionization reveal close similarities and indicate a comparable amount of excitation for the two different ionization mechanisms at high enough projectile energies. Received 25 February 2002 Published online 13 September 2002     

Lifetime measurements of some levels belonging to the 3p <Emphasis Type="Bold">5</Emphasis>nd ( , 5, 6, 7) configuration of ArI

Lifetimes of some 3p^5nd (n = 4, 5, 6, 7) levels of neutral argon have been measured by high frequency deflection technique with a delayed coincidence single photon counting arrangement. The measurements have been performed under conditions where pressure dependent effects are negligible. Lifetimes of some of the levels have been measured for the first time. The results have been compared with other experimental and theoretical values. Received 7 August 2002 / Received in final form 20 December 2002 Published online 24 April 2003