Stress Adaptation and the Brainstem with Focus on Corticotropin-Releasing Hormone

Stress adaptation is of utmost importance for the maintenance of homeostasis and, therefore, of life itself. The prevalence of stress-related disorders is increasing, emphasizing the importance of exploratory research on stress adaptation. Two major regulatory pathways exist: the hypothalamic–pituitary–adrenocortical axis and the sympathetic adrenomedullary axis. They act in unison, ensured by the enormous bidirectional connection between their centers, the paraventricular nucleus of the hypothalamus (PVN), and the brainstem monoaminergic cell groups, respectively. PVN and especially their corticotropin-releasing hormone (CRH) producing neurons are considered to be the centrum of stress regulation. However, the brainstem seems to be equally important. Therefore, we aimed to summarize the present knowledge on the role of classical neurotransmitters of the brainstem (GABA, glutamate as well as serotonin, noradrenaline, adrenaline, and dopamine) in stress adaptation. Neuropeptides, including CRH, might be co-localized in the brainstem nuclei. Here we focused on CRH as its role in stress regulation is well-known and widely accepted and other CRH neurons scattered along the brain may also complement the function of the PVN. Although CRH-positive cells are present on some parts of the brainstem, sometimes even in comparable amounts as in the PVN, not much is known about their contribution to stress adaptation. Based on the role of the Barrington’s nucleus in micturition and the inferior olivary complex in the regulation of fine motoric—as the main CRH-containing brainstem areas—we might assume that these areas regulate stress-induced urination and locomotion, respectively. Further studies are necessary for the field.     

具有检测电池容量功能的充电器设计

为解决市场主流充电器缺少电池容量检测功能以及电池充满电量后不能自动断电等问题,设计了一种以MSP430单片机为控制核心、DS1302为外围时钟电路芯片、具有检测电池容量功能的充电器,并给出了单元模块设计电路和配套的软件流程图。实验表明,该充电器可对锂电池、镍镉电池进行充电和放电,并提供两种电池容量检测方式,在采用传统电池容量检测方式测量时误差不超过5%;快速检测方式因节省时间,误差稍大。     

Call admission control in the microcell/macrocell overlaying system

Call admission control can significantly affect the performance of a cellular system by adding additional bandwidth to a wireless network. In this paper, we show how call admission control can be used to optimize the performance of a hierarchical cellular system. The hierarchical system we study is based on a novel frequency planning scheme, whereby both the micro and macro layers can share the same spectrum and a hard partition of the frequency spectrum is not needed. The original analysis of the hierarchical system showed that a significant capacity gain can be achieved by the scheme. However, this capacity is gained at the expense of the carrier-to-interference ratio (C/I) performance of the macrocells. In this paper, we show that call admission control can be used in hierarchical cellular systems to achieve a capacity gain without sacrificing the C/I performance of the macrocells     

Rate matching: a new approach to hidden terminal problem in ad hoc networks

Prior works on the hidden terminal problem in wireless networks often assume that the SNR requirement and the transmission range in a network are fixed. In fact, they are rate dependent. Because of this assumption, many of the prior conclusions about the hidden terminal problem are not accurate. A new analysis of the hidden terminal problem is presented in the paper. The new insights provided by the analysis lead to a rate-matching scheme for tackling the hidden terminal problem in wireless networks. The new method is simple, yet efficient, and requires no protocol changes from the 802.11 standard. NS2-based simulations are given in the paper to demonstrate the advantages of the new scheme.     

Advantages of visualization of organelle structure by high resolution scanning electron microscopy

Examination of subcellular structures in detail and in three dimensions (3D) by scanning electron microscopy (SEM) is now possible on a routine basis due to improvements in design of the modern scanning electron microscope and new methods of specimen preparation involving chemical removal of the cytosol and the cytoskeleton. Cells which have been fixed, frozen, cleaved, thawed, and subjected to cytosol removal exhibit constituents such as nuclear chromatin, cisternae of endoplasmic reticulum, mitochondria, and the Golgi complex in bold relief. This permits examination by SEM in 3D of these structures from several aspects at a resolution close to that of conventional transmission electron microscopy (TEM). As a result, minute changes in the 3D structure of subcellular components can now be easily and conveniently examined from many specimens and anatomical sites, in development, in a variety of physiological processes, and in disease. The SEM method offers many advantages over the various TEM techniques now used for similar purposes, since much larger areas of the specimen can be surveyed by SEM in a given time, sectioning is not required and minute 3D changes in nuclear and organelle structure can be identified and analyzed more easily. The advantages are such that a host of biological questions can now be answered by SEM which, so far, have resisted solution using only TEM techniques. In addition, a new field of pathological diagnosis using SEM may develop, using the advantages offered by the technique in exploring the cell's interior as well as cellular tissue organization.     

Effects of brefeldin-A on Golgi morphology in human cultured fibroblasts observed in three-dimensional stereo scanning electron microscopy

Brefeldin A (BFA) has been reported to cause disassembly of the Golgi. We have used three-dimensional (3-D) high-resolution scanning electron microscopy (HRSEM) to investigate these effects in human skin fibroblast cells. The spontaneous reassembly during prolonged exposure to BFA and some effects of forskolin were observed. A BFA concentration of 5μg/ml caused Golgi complexes to become vesicular, resulting in a progressive decrease in the size of the Golgi. Morphologic changes were visible within 2 min of BFA incubation, and by 30 min no identifiable Golgi could be found. Spontaneous reassembly of the Golgi apparatus upon the removal of the BFA or with continued long-term exposure with BFA could not be confirmed. Preliminary experiments with forskolin were not effective in reversing or inhibiting the effects of BFA in human fibroblast cells grown in culture. This inability for spontaneous reassembly and nonreversal by forskolin may reflect a differential effect of BFA in various cell types. HRSEM has proven to be useful for observing 3-D morphologic effects of BFA in Golgi.     

Strictly nonblocking directional-coupler-based switching networksunder crosstalk constraint

Directional-coupler (DC)-based switching systems can switch signals at the rate of several terabits per second. Such switches can also transmit signals with multiple wavelengths simultaneously. Despite these advantages, DCs suffer from an intrinsic crosstalk problem that must be overcome in building a robust switching system. In this paper, the principles of constructing strictly nonblocking DC-based photonic switching systems under various crosstalk constraints are explored. We demonstrate how crosstalk adds a new dimension to the theory of switching systems. We find the sufficient nonblocking condition for photonic networks under crosstalk constraints and demonstrate that some well-known nonblocking networks can tolerate a stricter crosstalk constraint while retaining their hardware complexity. The theory developed in the paper can guide us in making the design tradeoff between the level of crosstalk and the amount of hardware