Cumulant functions in optical coherence theory

Cumulant functions are introduced to describe the statistical state of a radiation field. These functions are simply related to the optical coherence functions but have some interesting features. It is shown that if the cumulant functions of all orders greater than some numberN ₀ vanish then they also vanish for all orders greater than 2. Thermal field is the only field having this property. This property holds whether the field is described by a classical stochastic process or by a quantum density operator. Further the particular operator ordering used in defining these cumulant functions for the quantized field affects only the second order cumulant function. To describe the statistical state of a vector field such as partially polarized or unpolarized radiation, one would need to introduce cumulant tensors.     

Gas phase activation energy for unimolecular dissociation of biomolecular ions determined by focused RAdiation for gaseous multiphoton ENergy transfer (FRAGMENT)

We present a novel approach for the determination of activation energy for the unimolecular dissociation of a large (>50 atoms) ion, based on measurement of the unimolecular dissociation rate constant as a function of continuous-wave CO(2) laser intensity. Following a short ( approximately 1 s) induction period, CO(2) laser irradiation produces an essentially blackbody internal energy distribution, whose 'temperature' varies inversely with laser intensity. The only currently available method for measuring such activation energies is blackbody infrared radiative dissociation (BIRD). Compared with BIRD, FRAGMENT: (a) eliminates the need to heat the surrounding ion trap and vacuum chamber to each of several temperatures (each requiring hours for temperature equilibration); (b) offers a three-fold wider range of effective blackbody temperature; and (c) extends the range of applications to include initially cold ions (e.g., gas-phase H/D exchange). Our FRAGMENT-determined activation energy for dissociation of protonated bradykinin, 1.2 +/- 0.1 eV, agrees within experimental error to the value, 1.3 +/- 0.1 eV, previously reported by Williams et al. from BIRD experiments. Copyright 1999 John Wiley & Sons, Ltd.     

Correction to: Motivations,benefits and challenges on ISO/IEC 17025 accreditation of higher education institution laboratories

Accreditation and Quality Assurance - Unfortunately, figure 3 was incorrectly published in the original publication and the correct version is updated here.     

Implementation of a quality management system in university test laboratories: a brief review and new proposals

Quality management systems are difficult to implement in university laboratories involved in teaching activities, R&D and provision of testing services, because of their peculiar characteristics. Testing services are not a priority, the performance of professionals is measured based on their teaching activities and publications, and the laboratories are shared with research and teaching activities. Hard efforts were made all around the world to overcome some of these difficulties. This paper analyzes the process of implementing a quality management system according to the ISO/IEC 17025 standard at two laboratories of the Federal University of Rio Grande do Sul, in Brazil. Some new solutions to solve the main problems typically originated on this type of environment are presented and compared with reports from the literature. It was concluded that it is perfectly possible for university laboratories to have their tests accredited according to standard ISO/IEC 17025, respecting their peculiarities and adopting creative solutions that meet the characteristics and the needs of each institution.     

Effects of visible light on the skin

Electromagnetic radiation has vast and diverse effects on human skin. Although photobiologic studies of sunlight date back to Sir Isaac Newton in 1671, most available studies focus on the UV radiation part of the spectrum. The effects of visible light and infrared radiation have not been, until recently, clearly elucidated. The goal of this review is to highlight the effects of visible light on the skin. As a result of advances in the understanding of skin optics, and comprehensive studies regarding the absorption spectrum of endogenous and exogenous skin chromophores, various biologic effects have been shown to be exerted by visible light radiation including erythema, pigmentation, thermal damage and free radical production. It has also been shown that visible light can induce indirect DNA damage through the generation of reactive oxygen species. Furthermore, a number of photodermatoses have an action spectrum in the visible light range, even though most of the currently available sunscreens offer, if any, weak protection against visible light. Conversely, because of its cutaneous biologic effects, visible light is used for the treatment of a variety of skin diseases and esthetic conditions in the form of lasers, intense pulsed light and photodynamic therapy.     

Current American landscape in laboratory accreditation according to ISO/IEC 17025

Accreditation and Quality Assurance - The number of laboratories worldwide seeking accreditation has increased considerably in the last years. These laboratories are from different institutions,...     

铌酸锶钡薄膜的微结构与电光性能的研究

本文叙述了使用溶胶凝胶法在MgO(0 0 1)的衬底上制备铌酸锶钡薄膜的过程 ,膜层厚度可达 5 μm。通过X射线衍射、摇摆曲线、扫描、拉曼散射光谱等方法研究了薄膜的微结构性能 ,实验发现 ,铌酸锶钡薄膜具有了较好的 (0 0 1)方向的优先取向性能 ,并且随着薄膜厚度的增加 ,其晶体取向性也会随之不断改进。熔石英的透明衬底上生长的SBN薄膜具有较大的电致双折射效应 ,其有效电光系数能够高达 6 6 2× 10 -11m/V。     

A process approach to ISO/IEC 17025 in the implementation of a quality management system in testing laboratories

The introduction of quality management systems (QMS) and the accreditation of laboratories according to ISO/IEC 17025 standard are not easy tasks, mainly for those laboratories located at teaching and research institutions. During the implementation of QMS at two testing laboratories of the Federal University of Rio Grande do Sul in Brazil, new solutions to overcome some of the difficulties inherent to this type of environment have been found. The knowledge acquired through this work has led to the proposition of some general steps incorporating a process approach presented in this article, which could be of use to laboratories in their pursuit for accreditation. This proposal suggests the use of strategic planning information, links the QMS objectives to the corresponding processes and sets a few indicators to monitor both performance of and improvements to the system.