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Local Area Network (local + area_network)
Kinds of Local Area Network Selected AbstractsDEA network computing in multi-stage parallel processesINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 3 2003Toshiyuki Sueyoshi DEA (Data Envelopment Analysis) is a managerial method that has been widely used for performance analysis in various public and private sectors. To deal with large-scale DEA problems, this research proposes the architecture of DEA network computing (LAN: Local Area Network) that is designed to coordinate a simultaneous use of multiple personal computers. An important feature of the proposed DEA computer architecture is that it is computationally structured in multi-stage parallel processes to enhance its algorithmic efficiency. The performance of the proposed network computing approach is tested and examined in a large simulation study. [source] Marking high-technology market evolution through the foci of market stories: the case of local area networksTHE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 6 2002Vasilis Theoharakis Previous research suggests that changing consumer and producer knowledge structures play a role in market evolution and that the sociocognitive processes of product markets are revealed in the sensemaking stories of market actors that are rebroadcasted in commercial publications. In this article, the authors lend further support to the story-based nature of market sensemaking and the use of the sociocognitive approach in explaining the evolution of high-technology markets. They examine the content (i.e., subject matter or topic) and volume (i.e., the number) of market stories and the extent to which content and volume of market stories evolve as a technology emerges. Data were obtained from a content analysis of 10,412 article abstracts, published in key trade journals, pertaining to Local Area Network (LAN) technologies and spanning the period 1981 to 2000. Hypotheses concerning the evolving nature (content and volume) of market stories in technology evolution are tested. The analysis identified four categories of market stories,technical, product availability, product adoption, and product discontinuation. The findings show that the emerging technology passes initially through a ,technical-intensive' phase whereby technology related stories dominate, through a ,supply-push' phase, in which stories presenting products embracing the technology tend to exceed technical stories while there is a rise in the number of product adoption reference stories, to a ,product-focus' phase, with stories predominantly focusing on product availability. Overall story volume declines when a technology matures as the need for sensemaking reduces. When stories about product discontinuation surface, these signal the decline of current technology. New technologies that fail to maintain the ,product-focus' stage also reflect limited market acceptance. The article also discusses the theoretical and managerial implications of the study's findings. [source] Performance evaluation of CSMA/ID MAC protocol for IP over WDM ring networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 11 2008Jih-Hsin Ho Abstract In this paper, a packet pre-classification media access control protocol based on a carrier sense multiple access with idle detection (CSMA/ID) scheme is investigated for supporting IP packets over all-optical WDM ring networks. The purpose of the protocol is to increase throughput and to decrease the packet transmission delay of IP packets over optical networks in a metropolitan area network. This protocol avoids both packet collision and packet fragmentation. In order to improve the utilization of the network, the packets transmitted from a local area network are first pre-classified into various class queues of an access point (AP) according to their length. After checking the available space based on the wavelength received by the receivers of the AP, the packets in the queues are transmitted. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency. The proposed network has short-term variations that introduce unfairness conditions. This problem could be overcome by assigning a quota on individual queues to allow all queues fair access. Copyright © 2008 John Wiley & Sons, Ltd. [source] Novel planar triple band monopole antenna for WiMAX/WLAN applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2010Hsien-Wen Liu Abstract A coplanar waveguide (CPW)-fed planar monopole antenna with triple band operation for worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) applications is presented. The antenna, which occupies a small size of 25 (L) × 25 (W) × 0.8 (H) mm3, is simply composed of a pentagonal radiating patch with two bent slots. By carefully selecting the positions and lengths of these slots, good dual stopband rejection characteristic of the antenna can be obtained, so that three operating bands covering 2.14,2.85, 3.29,4.08, and 5.02,6.09 GHz can be achieved. The measured results also demonstrate that the proposed antenna has good omnidirectional radiation patterns with appreciable gain across the operating bands, and is thus suitable to be integrated within the portable devices for WiMAX/WLAN applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2405,2408, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25497 [source] Dual band-notched ultra-wideband printed antenna with two different types of slotsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2010Jun-Bo Jiang Abstract A compact wideband printed antenna with dual band-notched characteristics for wireless local area network (WLAN) (2.4 GHz/5.8 GHz) is introduced. It is demonstrated that dual band rejection characteristics at 2.4 and 5.8 GHz with desired bandwidths can be obtained by using two different types of slots, one is a folded stripline slot on the radiation patch, and the other is a pair of inverted-L-shaped slot on the ground. The proposed antenna operates over 2.2,11 GHz for VSWR <2, while providing a band-stop function in the frequency bands of 2.3,2.9 GHz and 5.5,6.3 GHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1930,1933, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25411 [source] Dual-band hybrid coupler with extended bandwidthMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2010King Yin Cheung Abstract A dual-band branch-line quadrature coupler with extended bandwidth using simple three-section branch line is presented. This proposed design exhibits larger bandwidth than existing dual-band designs reported in previous literature. A dual-band branch-line coupler was designed and measured to give 34.5 and 16.4% bandwidth in the lower band and upper band, respectively, for an amplitude imbalance less than 1 dB. The achieved bandwidth is wide enough to cover wireless local area network and wideband code division multiple access applications. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2095,2098, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25405 [source] Design of dual-band antenna with U-shaped open stub for WLAN/UWB applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009Jung N. Lee Abstract In this article, we have proposed a dual-band antenna with U-shaped open stub for wideband local area network (WLAN)/ultra wideband (UWB) applications. The designed dual-band antenna consists of two semicircle radiating patches, a rectangular slot separating the two semicircles, one step for impedance matching, and coplanar waveguide (CPW) feeding. Two kinds of prototypes (CPW-fed UWB antenna and the dual-band antenna with U-shaped open stub) are fabricated and measured. Parametric studies and radiation characteristics for the two antennas are presented. The designed antenna has the figure-of-eight radiation pattern, wide bandwidth, and negligible dispersion over the operating frequency band. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 284,289, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24033 [source] Design of dual-band bandpass filter using diverse quarter-wavelength resonators for GPS/WLAN applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2008Hung-Wei Wu Abstract The novel compact dual-band bandpass filter (BPF) by using diverse quarter-wavelength (,/4) resonators for global position system (GPS)/wireless local area network (WLAN) applications is proposed for the first time. The use of two interdigital-like ,/4 resonators of the proposed BPF effectively provides the responses for GPS/WLAN at 1.575/5.7 GHz by properly arranging the ,/4 SIRs. Full-wave simulator IE3D is used to design the proposed BPF. Good agreement with responses of electromagnetic (EM) simulation and measurement is compared. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2694,2696, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23716 [source] Compact band-notched ultra-wideband printed antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2007Yi Ding Abstract A novel and compact ultra-wideband (UWB) printed monopole antenna with extended band-notched designs is presented. The antenna with a total size of 20 mm × 35 mm operates in a band from 3 to over 11 GHz (VSWR , 2), and shows omnidirectional radiation with a low cross-polarization in the range of the operated band. Measured results indicate that the antenna presents a notched-band from 5.1 to 6 GHz for VSWR , 3:1, which covers the wireless local area network (WLAN) band. The notched-band is produced by an embedded resonant cell (ERC). Experimental results show that the band-notched function can be controlled by adjusting the length of the ERC and area of the slot. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2686,2689, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22842 [source] Compact meander monopole antenna for tri-band WLAN applicationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2007Li-Na Zhang Abstract A novel printed meander monopole antenna for tri-band wireless local area network (WLAN) applications is presented. The antenna is composed of a meander strip and a straight strip with a gap between the ends of them, both printed on an inexpensive FR4 substrate, and is fed by a 50 , microstrip feeder with the notched ground plane. The operation bandwidth of the proposed antenna covers 2.4, 5.2, and 5.8 GHz WLAN bands with light weight and compact radiator size of only 12 × 7 mm2. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 986,988, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22314 [source] Printed pentagon monopole antenna with a band-notched functionMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2006Shun-Yun Lin Abstract In this study, we propose a design to obtain band-notching characteristics in printed planar monopoles. An ultra-wide band was achieved by means of the beveled upper edge of the rectangular patch with dimension as small as 55 mm2. On the other hand, it is necessary to notch certain bands to avoid interference from existing wireless local area network (WLAN), such as the 5.2 GHz band (5150,5350 MHz) and 5.8 GHz band (5725,5875 MHz), in spite of the adoption of the FCC for UWB communication systems operating between 3.1 and 10.6 GHz. This feature can be easily achieved by embedding an inverted-V-shape slot with length about one-half of the guided wavelength of the expected notched frequencies and along the boundary of the beveled radiating patch. This article presents the design of the proposed slotted monopole antenna, demonstrates the UWB operation with a notched frequency band, and analyzes the effects of the dimensions of the inverted-V-shape slot on the notched frequency band. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2016,2018, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21859 [source] Three-antenna MIMO system for WLAN operation in a PDA phoneMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2006Kin-Lu Wong Abstract A multiple input multiple output (MIMO) system using three EMC (electromagnetic compatible) chip antennas in a personal digital assistant (PDA) phone is demonstrated. The three EMC chip antennas are mounted at three corners of the system ground plane of the PDA phone and all generate a wide bandwidth covering the wireless local area network (WLAN) operation in the 2.4-GHz band (2400,2484 MHz). By adding a T-shaped shorted strip in the proposed MIMO antenna system, large improvements in the isolation (S12, S13, and S23 all less than ,20 dB) between any two antennas of the MIMO system are achieved. Detailed effects of the T-shaped shorted strip on the isolation improvement in the proposed MIMO antenna system are analyzed. Radiation characteristics of the three antennas are also studied. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1238,1242, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21665 [source] Narrow flat metal-plate antenna for dual-band WLAN operationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2003Chi-Yin Fang Abstract A novel dual-band antenna made of a narrow, rectangular, flat metal plate for wireless local area network (WLAN) operation in the 2.4- and 5.2-GHz bands is presented. The antenna comprises a larger radiating arm, a smaller radiating arm, and a shorting portion. The larger and smaller radiating arms control a lower resonant mode at about 2.4 GHz and an upper resonant mode at about 5.2 GHz, respectively, and are connected to each other through the shorting portion. The antenna is easily excited by using a 50, mini coaxial line and shows good antenna performance. The proposed antenna design is described and experimentally studied. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 398,400, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11072 [source] Broadband circularly polarized inverted-L patch antennaMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2003Che-Wei Su Abstract An innovative design of a corner-truncated inverted-L patch antenna for achieving circular polarization (CP) operation over a wide bandwidth is presented. The antenna has a thick air-layer substrate; however, it can be easily excited using a probe feed with a short probe pin. CP operation is obtained by selecting an optimal size of the truncated corners, and good impedance matching over a wide bandwidth is obtained by using a beveling technique on the vertical portion of the inverted-L patch. For a prototype constructed for wireless local area network (WLAN) operation in the 2.4-GHz band (2.4,2.484 GHz), the obtained CP bandwidth (3-dB axial ratio) reaches about 7%, and the measured antenna gain is about 8.0 dBi across the CP bandwidth. Details of the antenna design and the experimental results are presented. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 134,136, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10995 [source] Analysing disruptive potential: the case of wireless local area network and mobile communications network companiesR & D MANAGEMENT, Issue 1 2005Stefan Hüsig In this article, we analyse the prediction that wireless local area network (W-LAN) technologies will be disruptive for incumbent mobile communications network operators. For this purpose, we develop a methodology of guided interviews to assess technologies for their disruptive characteristics based on theory of disruptive technology developed by Christensen (1997) and recent extensions. The application of our comprehensive step-by-step method improves the precision of the disruptive technology concept and its usability for practitioners to make ex ante distinctions between disruptive technologies and other phenomena caused by emerging technologies. Our method predicts that contrary to common assumptions, W-LAN is not likely to represent a disruptive technology for the established mobile communications network firms in terms of Christensen's concept. This research was conducted in close collaboration with Vodafone Pilotentwicklung, an R&D and technology monitoring unit of the Vodafone Group. Vodafone provided part of the empirical data through expert interviews and market reports. [source] Performance analysis of IEEE 802.11 DCF with stochastic reward nets,INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2007R. Jayaparvathy Abstract In this paper, we present a performance study to evaluate the mean delay and the average system throughput of IEEE 802.11-based wireless local area networks (WLANs). We consider the distributed co-ordination function (DCF) mode of medium access control (MAC). Stochastic reward nets (SRNs) are used as a modelling formalism as it readily captures the synchronization between events in the DCF mode of access. We present a SRN-based analytical model to evaluate the mean delay and the average system throughput of the IEEE 802.11 DCF by considering an on,off traffic model and taking into account the freezing of the back-off counter due to channel capture by other stations. We also compute the mean delay suffered by a packet in the system using the SRN formulation and by modelling each station as an M/G/1 queue. We validate our analytical model by comparison with simulations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Achieving performance enhancement in IEEE 802.11 WLANs by using the DIDD backoff mechanismINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2007P. Chatzimisios Abstract Wireless local area networks (WLANs) based on the IEEE 802.11 standards have been widely implemented mainly because of their easy deployment and low cost. The IEEE 802.11 collision avoidance procedures utilize the binary exponential backoff (BEB) scheme that reduces the collision probability by doubling the contention window after a packet collision. In this paper, we propose an easy-to-implement and effective contention window-resetting scheme, called double increment double decrement (DIDD), in order to enhance the performance of IEEE 802.11 WLANs. DIDD is simple, fully compatible with IEEE 802.11 and does not require any estimation of the number of contending wireless stations. We develop an alternative mathematical analysis for the proposed DIDD scheme that is based on elementary conditional probability arguments rather than bi-dimensional Markov chains that have been extensively utilized in the literature. We carry out a detailed performance study and we identify the improvement of DIDD comparing to the legacy BEB for both basic access and request-to-send/clear-to-send (RTS/CTS) medium access mechanisms. Copyright © 2006 John Wiley & Sons, Ltd. [source] Performance analysis of the IEEE 802.11 MAC protocol for wireless LANsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2005P. Chatzimisios Abstract Wireless local area networks (WLANs) are extremely popular being almost everywhere including business, office and home deployments. The IEEE 802.11 protocol is the dominating standard for WLANs. The essential medium access control (MAC) mechanism of 802.11 is called distributed co-ordination function (DCF). This paper provides a simple and accurate analysis using Markov chain modelling to compute IEEE 802.11 DCF performance, in the absence of hidden stations and transmission errors. This mathematical analysis calculates in addition to the throughput efficiency, the average packet delay, the packet drop probability and the average time to drop a packet for both basic access and RTS/CTS medium access schemes. The derived analysis, which takes into account packet retry limits, is validated by comparison with OPNET simulation results. We demonstrate that a Markov chain model presented in the literature, which also calculates throughput and packet delay by introducing an additional transition state to the Markov chain model, does not appear to model IEEE 802.11 correctly, leading to ambiguous conclusions for its performance. We also carry out an extensive and detailed study on the influence on performance of the initial contention window size (CW), maximum CW size and data rate. Performance results are presented to identify the dependence on the backoff procedure parameters and to give insights on the issues affecting IEEE 802.11 DCF performance. Copyright © 2005 John Wiley & Sons, Ltd. [source] Roaming and service management in public wireless networks using an innovative policy management architectureINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 2 2005Idir Fodil Nowadays, public wireless local area networks (WLANs), commonly called hotspots, are being largely deployed by WISPs (Wireless Internet Service Providers) as a means of offering ubiquitous Internet access to their customers. Although a substantial number of solutions have been proposed to improve security, mobility and quality of service on the wireless area, access network management which is mandatory remains a very significant concern. This paper describes RSM-WISP, a new management architecture designed for WISPs to facilitate the implementation and management of the services they offer at the access side of the WLAN, and to manage roaming contracts between WISPs. Our architecture is based upon the policy-based management principles as introduced by the IETF, combined with more intelligence at the network edge. RSM-WISP adopts an architecture that is composed of two elements: a WISP management center (MC) that deploys policies and monitors all the WLANs, and a programmable access router (CPE) located in each WLAN. The CPE ensures service enforcement, service differentiation (access to different service levels) and guarantee, user access management, and dynamic WLAN adaptation according to the user's SLA (service level agreement). It also permits automatic service updates according to the user's requirements. Concerning roaming management, this is achieved on the CPE through multiple service provider support capabilities. This approach provides WISPs with a simple, flexible and scalable solution that allows easy service deployment and management at the access. This management architecture has been implemented, tested and validated on the 6WINDGate routers.,Copyright © 2005 John Wiley & Sons, Ltd. [source] A 3-V variable-gain amplifier in Si/SiGe BiCMOS technology for 5-GHz WLAN applicationsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2005F. Alimenti Abstract A variable-gain class-A amplifier for 5-GHz wireless local area networks (WLAN) applications is developed using commercial 0.35-,m Si/SiGe BiCMOS technology. The amplifier is based on a cascode differential pair and is fully integrated with input and output matching networks. The design starts with application of the Cripps' method and it is further refined by nonlinear harmonic-balance simulations. These simulations are in good agreement with the measurements carried out at wafer level on a realized prototype. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE 15, 2005. [source] Telerobotic systems design based on real-time CORBAJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 4 2005Michele Amoretti A new class of telerobotic applications is making its way into research laboratories, fine arts or science museums, and industrial installations. Virtual laboratories and remote equipment maintenance are examples of these applications, which are built exploiting distributed computing systems and Internet technologies. Distributed computing technologies provide several advantages to telerobotic applications, such as dynamic and multiuser access to remote resources and arbitrary user locations. Nonetheless, building these applications remains a substantial endeavor, especially when performance requirements must be met. The aim of this paper is to investigate how mainstream and advanced features of the CORBA object-oriented middleware can be put to work to meet the requirements of novel telerobotic applications. We show that Real-Time CORBA extensions and asynchronous method invocation of CORBA services can be relied upon to meet performance and functional requirements, thereby enabling teleoperation on local area networks. Furthermore, CORBA services for concurrency control and large-scale data distribution enable geographic-scale access for robot teleprogramming. Limitations in the currently available implementations of the CORBA standard are also discussed, along with their implications. The effectiveness and suitability for telerobotic applications of several CORBA mechanisms are tested first individually and then by means of a software framework exploiting CORBA services and ensuring component-based development, software reuse, low development cost, fully portable real-time and communication support. A comprehensive telerobotic application built based on the framework is described in the paper and evaluated on both local and wide area networks. The application includes a robot manipulator and several sensory subsystems under concurrent access by multiple competing or collaborating operators, one of which is equipped with a multimodal user interface acting as the master device. © 2005 Wiley Periodicals, Inc. [source] A compact ultra-wideband bandpass filter with WLAN notch bandMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2009Pai-Yi Hsiao Abstract A compact ultra-wideband (UWB) bandpass filter (BPF) with notch band is presented using a trilayer structure. The band elimination is essential for preventing the strong narrow band interference from the wireless local area networks within the allocated UWB spectrum. The sharp rejection of the unwanted band is introduced by adding a U-shape resonator on the middle layer. The design is not only realized theoretically but also verified by a full-wave electromagnetic simulation. The proposed UWB BPF is fabricated by an FR4 substrate material with the permittivity of 4.4 and the thickness of 0.8 mm. The total area is 8 mm × 6 mm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 503,507, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24093 [source] Broadband coplanar waveguide-fed slot antenna for wireless local area networks and microwave imaging applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2007Mohammod Ali Abstract A broadband CPW-fed semicircular slot antenna is proposed for 2,6 GHz WLAN (wireless local area networks) and microwave imaging applications. The total dimension of the bidirectional slot antenna is 80 mm by 50 mm and is designed on a 0.5-mm-thick Duroid 5880 substrate (dielectric constant = 2.2). The antenna operates from 2 to 6 GHz within VSWR of 2.5:1. The same antenna on a combination rectangular cylindrical cavity with cavity depth of 10 mm provides a directional beam, 11 dB front-to-back (F/B) ratio and a bandwidth of 63% (2.8,5.4 GHz). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 846,852, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22276 [source] Marking high-technology market evolution through the foci of market stories: the case of local area networksTHE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 6 2002Vasilis Theoharakis Previous research suggests that changing consumer and producer knowledge structures play a role in market evolution and that the sociocognitive processes of product markets are revealed in the sensemaking stories of market actors that are rebroadcasted in commercial publications. In this article, the authors lend further support to the story-based nature of market sensemaking and the use of the sociocognitive approach in explaining the evolution of high-technology markets. They examine the content (i.e., subject matter or topic) and volume (i.e., the number) of market stories and the extent to which content and volume of market stories evolve as a technology emerges. Data were obtained from a content analysis of 10,412 article abstracts, published in key trade journals, pertaining to Local Area Network (LAN) technologies and spanning the period 1981 to 2000. Hypotheses concerning the evolving nature (content and volume) of market stories in technology evolution are tested. The analysis identified four categories of market stories,technical, product availability, product adoption, and product discontinuation. The findings show that the emerging technology passes initially through a ,technical-intensive' phase whereby technology related stories dominate, through a ,supply-push' phase, in which stories presenting products embracing the technology tend to exceed technical stories while there is a rise in the number of product adoption reference stories, to a ,product-focus' phase, with stories predominantly focusing on product availability. Overall story volume declines when a technology matures as the need for sensemaking reduces. When stories about product discontinuation surface, these signal the decline of current technology. New technologies that fail to maintain the ,product-focus' stage also reflect limited market acceptance. The article also discusses the theoretical and managerial implications of the study's findings. [source] Low-power millimeter wave radiations do not alter stress-sensitive gene expression of chaperone proteinsBIOELECTROMAGNETICS, Issue 3 2007M. Zhadobov Abstract This article reports experimental results on the influence of low-power millimeter wave (MMW) radiation at 60 GHz on a set of stress-sensitive gene expression of molecular chaperones, namely clusterin (CLU) and HSP70, in a human brain cell line. Selection of the exposure frequency is determined by its near-future applications for the new broadband civil wireless communication systems including wireless local area networks (WLAN) for domestic and professional uses. Frequencies around 60 GHz are strongly attenuated in the earth's atmosphere and such radiations represent a new environmental factor. An exposure system operating in V-band (50,75 GHz) was developed for cell exposure. U-251 MG glial cell line was sham-exposed or exposed to MMW radiation for different durations (1,33 h) and two different power densities (5.4 µW/cm2 or 0.54 mW/cm2). As gene expression is a multiple-step process, we analyzed chaperone proteins induction at different levels. First, using luciferase reporter gene, we investigated potential effect of MMWs on the activation of transcription factors (TFs) and gene promoter activity. Next, using RT-PCR and Western blot assays, we verified whether MMW exposure could alter RNA accumulation, translation, or protein stability. Experimental data demonstrated the absence of significant modifications in gene transcription, mRNA, and protein amount for the considered stress-sensitive genes for the exposure durations and power densities investigated. The main results of this study suggest that low-power 60 GHz radiation does not modify stress-sensitive gene expression of chaperone proteins. Bioelectromagnetics 28:188,196, 2007. © 2006 Wiley-Liss, Inc. [source] | ||||||||||||||||