Isolation and identification of a novel Ala-Pro-Gly-Trp-amide-related peptide inhibiting the motility of the mature oviduct in the cuttlefish, Sepia officinalis

A novel myotropic neuropeptide was isolated from 110 optic lobes (OL) of mature females of the cuttlefish Sepia officinalis L. by mean of high performance liquid chromatography (HPLC). The peptide inhibits the motility of the oviduct by decreasing the tonus, the frequency and the amplitude of the contractions. The primary structure of the peptide was determined as Gly-Trp-NH2. This new dipeptide is closely related to the Ala-Pro-Gly-Trp-NH2 family first identified in gastropod molluscs. On the perfused oviduct, GWa appeared to be 3000 times more potent than APGW-amide. The processing of synthetic APGWa into GWa by diaminopeptidyl activity has been clearly observed in OL extract. Nevertheless, the analysis in MALDI-MS of HPLC OL fractions did not reveal any APGWa related peptides of the known: APGWa, KPGWa, RPGWa and TPGWa. GWa could be processed from a not yet identified APGWa related peptide.     

The vesicular monoamine transporter: from chromaffin granule to brain

All characterized monoaminergic cells utilize the same transport system for the vesicular accumulation of monoamines prior to their release. This system operates in neuronal (catecholaminergic, serotoninergic or histaminergic) as well as in endocrine or neuroendocrine cells. For several decades, chromaffin granules from bovine adrenal medulla have been used as a model system, allowing progress in the understanding of the biophysics, the biochemistry and the pharmacology of the monoamine vesicular transporter. The transporters from rat, bovine and man have been cloned. Surprisingly, two genes encode different isoforms of the protein which are differentially expressed in monoaminergic systems. The conjunction of recombinant DNA techniques and expression in secretory or non-secretory cells with the large body of data obtained on the chromaffin granule transporter has allowed rapid progress in the study of the protein. But interestingly enough, this progress has open new possibilities in the study of biological problems, especially in the brain. The transporter is useful for the determination of the relationship between small and large dense core vesicles, for the understanding of the mechanism of the drugs such as 1-methyl-4-phenylpyridinium (MPP+), tetrabenazine or amphetamines, and as a marker in brain development. The possibility of regulations at the vesicular transporter level and of their effect on the quantum size has to be investigated. The vesicular monoamine transporter is also an important target for brain imaging.     

Water-based polymers as pressure-sensitive adhesives—viscoelastic guidelines

Water-based polymers have been widely used as pressure-sensitive adhesives (PSAs). This article addresses the fundamental viscoelastic parameters that govern PSA performance. The viscoelastic behavior of polymers before and after resin tackification is investigated. Commercial acrylic, CSBR, natural rubber emulsion polymers, and low M_W petroleum-based hydrocarbon resins with various softening points are used to demonstrate the tackification effects. Basic guidelines for selecting the appropriate polymer/resin system to achieve the target performance are given. © 1995 John Wiley & Sons, Inc.     

Blend structure of commingled plastic from recycled polyethylene and polystyrene

The hierarchical morphology of commingled plastic waste in the form of thick beams prepared by the ET-1 process has been examined. Blends of recycled high-density polyethylene (RHDPE, New Jersey Curbside Tailings) with 25 and 35 wt % expanded polystyrene (EPS) were compared with blends of a virgin high-denisty polyethylene resin (VHDPE). At the macroscale, observed with the optical microscope, the beams consisted of a solid skin that extended about one-third of the distance to the center of the beam and a voided core with about half the density of the skin. The phase morphology of the skin at the microscale was characterized by examining etched cryogenic fracture surfaces in a scanning electron microscope. The blends of RHDPE and VHDPE exhibited a gradient morphology with highly elongated EPS domains near the edge and spherical or co-continuous EPS domains closer to the core. The morphology gradient was created by the competition between the relaxation rate of the melt-flow morphology and the cooling rate in the mod. In addition to high-density polyethylene, a variety of other components were identified in RHDPE by photoacoustic infrared and thermal analysis. These included polypropylene, polystyrene, poly(ethylene terephthalate), and chunks of nonpolymeric material. As a result of the heterogeneous composition, the crystallinity of RHDPE was significantly lower than that of VHDPE. © 1994 John Wiley & Sons, Inc.     

Physiological responses during data retrieval: Comparison of constant and variable system response times

Ten subjects solved 50 database queries consecutively presented on a video display terminal (VDT). Each query required solution within 45 s of its initial presentation to avoid a reduction in potential earnings. A solution required the correct selection of 3 successive hypertext indices hierarchically structured from the query to the data answer. Under a constant system response time (SRT) condition, each selection of a hypertext index was followed by an 8-s delay before another database level, consisting of both indices and data, was presented. Under a variable SRT condition, SRTs varied between 1 and 30 s, with a mean of 8 s. Twenty-five successive queries were presented under each condition, and the order of conditions varied unsystematically across subjects. Systolic blood pressure, mean arterial blood pressure, and heart rate showed pronounced elevations during task performance, in comparison to a resting baseline. Diastolic blood pressure and masseter muscle electromyograph (EMG) response did not change reliably over baseline. Intersubject variability in EMG response was, however, related to heart-rate variability during task performance. No differential physiological effects of SRT conditions were observed. An eleventh novice subject's cardiovascular responses habituated over five successive performance sessions, but when new queries were introduced, heart rate magnitude increased, showing the reversibility of the effect under novel performance demands. These data show that tonic cardiovascular responses may be evoked by a time-pressured and realistic human-computer interaction. The laboratory preparation may emulate functional properties of conditions that prevail in the VDT workplace.     

Invariant-theoretic methods in scene analysis and structural mechanics

We discuss possible applications of invariant theory to unsolved problems in applied geometry. In particular, we discuss projective conditions for correctness of plane drawings of 3-dimensional geometric forms, and for special mechanical behavior of bar-and-joint structures.     

Power Control Based QoS Provisioning for Multimedia in W-CDMA

Third generation wireless communication systems will support multimedia, and W-CDMA will be the common air interface technology. Due to the interference limited nature of CDMA, power is the main resource of the network, and power control is a means of resource management. In this article, we introduce Dynamic Resource Scheduling (DRS) as a framework which employs power control for QoS provisioning of multimedia traffic in W-CDMA. In DRS, we propose the application of optimal power assignment to the W-CDMA architecture, and we also suggest several implementation strategies. A simulation model of the Japanese W-CDMA standard (ARIB) has been developed for performance evaluation. The DRS framework is shown to accommodate different service classes efficiently by optimal resource management. Quantitative advantages are proven in terms of gains in capacity, throughput, power saving and QoS stability.     

WiFi: what's next?

WiFi, also known as 802.11b, has become the preferred technology for wireless local area networking in both business and home environments. Even though it was designed primarily for private applications, WiFi is also being deployed in public places to create so-called hotspots, where WiFi-capable users can obtain broadband Internet access. This new domain of application could be the major future market opportunity for WiFi, but in order to take advantage of it, several key challenges, both technical and business-related, must be overcome. We outline these challenges and discuss approaches to solutions.