Cellular composition characterizing postnatal development and maturation of the mouse brain and spinal cord

The process of development, maturation, and regression in the central nervous system (CNS) are genetically programmed and influenced by environment. Hitherto, most research efforts have focused on either the early development of the CNS or the late changes associated with aging, whereas an important period corresponding to adolescence has been overlooked. In this study, we searched for age-dependent changes in the number of cells that compose the CNS (divided into isocortex, hippocampus, olfactory bulb, cerebellum, ‘rest of the brain’, and spinal cord) and the pituitary gland in 4–40-week-old C57BL6 mice, using the isotropic fractionator method in combination with neuronal nuclear protein as a marker for neuronal cells. We found that all CNS structures, except for the isocortex, increased in mass in the period of 4–15 weeks. Over the same period, the absolute number of neurons significantly increased in the olfactory bulb and cerebellum while non-neuronal cell numbers increased in the ‘rest of the brain’ and isocortex. Along with the gain in body length and weight, the pituitary gland also increased in mass and cell number, the latter correlating well with changes of the brain and spinal cord mass. The majority of the age-dependent alterations (e.g., somatic parameters, relative brain mass, number of pituitary cells, and cellular composition of the cerebellum, isocortex, rest of the brain, and spinal cord) occur rapidly between the 4th and 11th postnatal weeks. This period includes murine adolescence, underscoring the significance of this stage in the postnatal development of the mouse CNS

A situational method engineering approach to requirements elicitation workshops in the software development process

The elicitation of requirements for software systems is one of the most critical and complex activities within the development lifecycle. Although the subject has received some degree of attention in the research literature, there remains a need for situational methods and processes that can be easily utilized by the majority of practitioners in typical projects. In this paper we present a flexible yet systematic approach to the early stages of requirements elicitation in software development, based on collaborative workshops and the construction of a lightweight situational method, within a general process framework. The research provides practitioners with an approach to requirements elicitation that can be readily applied to real-world projects in order to improve both the process and the results. The work also offers researchers an example of how lightweight situational method engineering can be applied to very practical activities and situations in the software process. Copyright © 2006 John Wiley & Sons, Ltd

Thermal response of a nanoscale hot-wire in subsonic and supersonic flows

A comprehensive characterization of the thermal response of nanoscale hot-wire probes is performed in both subsonic and supersonic flows. A constant current anemometer was designed for the measurement of the intrinsic thermal inertia of hot-wire probes. In particular, the nanoscale probe is considered with the effect of gold-plating on supporting structure of the targeted sensing element. Gold-plated nanoscale probes present a response time one order of magnitude smaller than conventional cylindrical hot-wire probes. Heat transfer simulations show that the temperature profile is considerably modified by the addition of a conductive metal layer, hence increasing the sensor's frequency response in both subsonic and supersonic flows. The increase of frequency response is finally exemplified by the numerical computation of the power spectral density of a turbulent flow signal without any electric compensation of the hot-wire signal