Luminescence studies of polymer behaviour

Luminescence techniques can be used to study polymer systems both as an analytical tool and as a means of studying molecular behaviour. In the latter context, some very interesting information may be obtained on a variety of molecular and energy transport processes. Measurements of luminescence intensity and quenching can be used to observe electronic energy transfer processes (both along polymer chains and from polymer chains to additive molecules). These have a technical importance in that they are the photophysical processes which precede the chemical phenomena important in photodegradation or photostabilisation of polymers. The basic criteria for energy transfer are introduced and examples are given of “down-chain” energy migration coefficients for a number of polymers. Studies of the depolarisation of luminescence can be used as a measurement of rotation in the electronic excited state of the photoactive group. Fluorescence depolarisation is introduced and examples are given of processes with nanosecond relaxation times. The concept of phosphorescence depolarisation is also mentioned, and the first use of this to study processes with millisecond relaxation times is illustrated.     

Diaphragm activation with intramuscular stimulation in dogs

We studied in 10 supine anesthetized dogs diaphragm contraction produced by electrical activation with intramuscular electrodes surgically implanted in the ventral surface of the diaphragm and compared this with activation of the ipsilateral phrenic nerve (C5, 6, and 7) before it entered the thorax. Repetitive 40-Hz pulse trains with supramaximal current stimulus were used after hyperventilation of the animals to apnea. A single intramuscular electrode within 1 to 2 cm of the site of phrenic nerve entry into the diaphragm produced a mean transdiaphragmatic pressure of 12.0 cm H2O +/- 0.97 SE and mean tidal volume of 0.27 L +/- 0.04 SE. Mean values observed with phrenic nerve stimulation were not statistically different, and both electrode systems produced equivalent outward abdominal motion and upper rib cage paradox, as monitored by inductive plethysmography. There was no difference in gas exchange during stimulation with a single hemidiaphragm electrode and mechanical ventilation compared at the same tidal volume and respiratory rate. Blockade of neuromuscular transmission with curare eliminated intramuscular and phrenic nerve stimulation proportionately, suggesting that activation of the diaphragm is dependent in both cases on the phrenic nerve. This technique does not entail manipulation of the phrenic nerve and may have clinical application as an alternative technique for diaphragm pacing.     

Theory of modal character, field structure, and losses for semiconductor lasers

The contemporary semiconductor laser oscillates and radiates power simultaneously in many of the characteristic modes of its cavity, perhaps only a few for the "stripe" laser neat threshold, but hundreds or thousands for power lasers. This article provides a comprehensive theory of the modal characteristics: field structure, polarization, characteristic frequency, radiation pattern, and losses. A new theory is developed for cavities with a nonuniform dielectric. The subject matter is indispensable to understanding or use of the new nonlinear theory of laser processes. Much of it is also relevant to dielectric, optical transmission systems in general     

内网接入控制和安全防护系统的设计

文章针对当前内网存在的安全问题,对基于身份认证的内网安全技术进行了研究,设计了一个安全防护系统。着重分析了系统的体系结构及软件结构,并给出了认证流程。     

论我国会计职业道德建设

会计职业道德是一般社会道德在会计业务或活动中的具体体现,有广义与狭义之分,具有利益调节手段、广泛的社会性、自律性、主观能动性、形式多样性等特征。我国的会计职业道德建设尽管取得了一些成绩,但对我国会计职业道德建设的重要性认识不足,没有形成科学、系统的会计职业道德体系,也未能建立起系统、完整的会计职业道德颁布、落实、教育、评价与督导体系等问题。应树立“洋为中用”、“古为今用”、“与时俱进”的指导思想,实现会计职业道德内容上的原则性与可操作性的有机结合、体系上的全面性与重要性的科学设计。     

论康德绝对命令的实践理路及价值指归

康德所谓绝对命令是指主体无条件地服从义务以实现道德价值的道德律令。本文论述了绝对命令的双向实践理路：意志自律——绝对命令的我向规定；“以人为目的”——绝对命令的外向要求；理性幸福——绝对命令的价值指归。     

在艺术设计学科中的素描问题新探

纯美术教育和艺术设计教育分属不同的教育体系，而目前艺术设计教育中有许多直接从纯美术承接的结构内容，这或许会影响艺术设计教育的良性发展。作为基础课程的传统的素描教学不能适应艺术设计的培养目标，如何调整教学目标和教学方式的问题突显出来。参照艺术设计的三大构成基础进行改革，将是一种有效的方式。