111 research outputs found
Nuclear mutations affecting mitochondrial structure and function in Chlamydomonas
Wild type cells of the green alga Chlamydomonas reinhardtii can grow in the in the dark by taking up and respiring exogenously supplied acetate. Obligate photoautotrophic (dark dier, dk) mutants of this alga have been selected which grow at near wild type rates in the light, but rapidly die when transferred to darkness because of defects in mitochondrial structure and function. In crosses of the dk mutants to wild type, the majority of the mutants are inherited in a mendelian fashion, although two have been isolated which are inherited in a clearly nonmendelian fashion. Nine mendelian dk mutants have been analyzed in detail, and belong to eight different complementation groups representing eight gene loci. These mutants have been tentatively grouped into three classes on the basis of the pleiotropic nature of their phenotypic defects. Mutants in Class I have gross alterations in the ultrastructure of their mitochondrial inner membranes together with deficiencies in cytochrome oxidase and antimycin/rotenone-sensitive NADH-cytochrome c reductase activities. Mutants in Class II have a variety of less severe alterations in mitochondrial ultrastructure and deficiencies in cytochrome oxidase activity. Mutants in Class III have normal or near normal mitochondrial ultrastructure and reduced cytochrome oxidase activity. Eight of the nine mutants show corresponding reductions in cyanide-sensitive respiration
THE POST-FORDIST TRANSFORMATION: INFORMATION TECHNOLOGY AND ORGANIZATIONAL CHANGE
A new family of organizational forms, collectively labeled post-For(list, is steadily emerging in response to a perceived decline in the dominance of mass production and a rapidly changing competitive environment (Boynton and Victor 1991, 1992). These new forms have been variously labeled flexible specialization, mass customization, Toyotism, dynamic stability, and learn manufacturing. Understanding the rise of post-Fordism and the fundamental changes it necessitates, particularly in the use of information technology, is essential to cuirent IT theory and research (Allen and Boynton 1991; Pine 1992). This research combines qualitative field research with analysis of survey-based longitudinal data to better understand the role of IT in the post-Fordist transformation. This paper will discuss this research in process. Understanding the post-Fordist revolution requires first recognizing the challenge to the mass-production model. Fordist mass production was based on sustaining productivity growth by means of economies of scale and an increasingly elaborate division of labor (Piore and Sabel 1984). This foundation is now challenged by both market change and technological innovation. The large undifferentiated markets of the past centuty are increasingly saturated and fragmenting (Pine 1992). In addition, technological innovations are fueling the search for more flexible production processes. The market and technological changes are, in turn creating new strategic principles requiring simultaneously efficiency and flexibility (Boynton and Victor 1991, 1992). Fordist mass production can neither capitalize on the new strategic options nor compete with forms that do so (Womack, Jones and Roos 1990). Information technology is central to the recent rise of flexible technology, including modular and rapid-development software tools, numerically controlled machine tools, robots, flexible information and database storage and retrieval systems, EDI, and computer automated manufacturing (Pine 1992). Information technology is also a central factor in the emergence of the post-Fordist forms themselves, enabling globally networked organizations, powerful and flexible financial control systems, increasingly decentralized production and service delivery, and new kinds of organizational learning (Nonaka 1983; Boynton and Victor 1992). We are employing two research approaches to study the role of information technology in the emergence of post-Fordist forms: first, a qualitative approach based on intense field-based research and, second, analysis of longitudinal data based on survey research. We are currently conducting field based research with a number of firms, including Citibank, Coming Inc., Asea Brown Bovari, Bally Engineering, Westpac, and Lutron Electronics. To date, our investigations indicate several key requirements in the transformation to post-Fordist form: (1) the decoupling of IT asset investments from short-term product needs in order to build general-purpose process capabilities to match changes in service requirements; (2) the combining of firm-wide knowledge into a general purpose IT architecture in order to increase the speed product introduction rates; and (3) the influence of market as a precursor of post-Fordist pressures for increased product flexibility. We are also using a large scale survey methodology to explore the extent of the post-Fordist transition across industries and the level of IT investment employed to support this transition. Our large-scale survey data comes from the Profit Impact of
Marketing Strategy (PIMS) project. Fifteen consecutive years of data have been organized. The analysis will utilize MANCOVA on a year-by-year basis to assess the existence and relative performance of combination (post-Fordist) strategies compared to firms pursuing low-cost or differentiation (FordisO strategies. Early findings indicate that trends toward combination low-cost, differentiated strategies are increasing by industry. The extent of IT investment that coincides with transformation to post-Fordist strategy is part of the next phase of data analysis within the PLMS database
AN EXAMINATION OF MANAGERIAL STRATEGIES FOR INCREASING INFORMATION TECHNOLOGY PENETRATION IN ORGANIZATIONS
This paper describes an empirical study comparing two competing perspectives for explaining information technology (IT) penetration in organizations. IT penetration is defined as the extent to which IT is embedded within an organization\u27s strategic, managerial, and operational work systems. With the first perspective, IT penetration is hypothesized to be related to the implementation of a comprehensive set of management processes for the information systems (IS) function. With the second perspective, IT penetration is hypothesized to be related to the effectiveness of IT-related interactions among an organization\u27s managers, To strengthen the study\u27s research design, the hypotheses are examined separately across two samples of organizations. Senior ]S executives completed the study\u27s research instrument. Respondents in the first sample represented 132 large organizations across a variety of industries, while the respondents in the second sample represented 44 business units within a large, high teChnology firm. IT penetration and IT-related managerial interactions were measured at a subunit level, while IS management processes were measured at an organizational level. The study\u27s findings supported the research hypotheses. *The authors wish to thank Omar El Sawy and anonymous reviewers for their helpful comments on earlier drafts of this paper
Metropolitan quantum key distribution with silicon photonics
Photonic integrated circuits (PICs) provide a compact and stable platform for
quantum photonics. Here we demonstrate a silicon photonics quantum key
distribution (QKD) transmitter in the first high-speed polarization-based QKD
field tests. The systems reach composable secret key rates of 950 kbps in a
local test (on a 103.6-m fiber with a total emulated loss of 9.2 dB) and 106
kbps in an intercity metropolitan test (on a 43-km fiber with 16.4 dB loss).
Our results represent the highest secret key generation rate for
polarization-based QKD experiments at a standard telecom wavelength and
demonstrate PICs as a promising, scalable resource for future formation of
metropolitan quantum-secure communications networks
Multimodal Functional Network Connectivity: An EEG-fMRI Fusion in Network Space
EEG and fMRI recordings measure the functional activity of multiple coherent networks distributed in the cerebral cortex. Identifying network interaction from the complementary neuroelectric and hemodynamic signals may help to explain the complex relationships between different brain regions. In this paper, multimodal functional network connectivity (mFNC) is proposed for the fusion of EEG and fMRI in network space. First, functional networks (FNs) are extracted using spatial independent component analysis (ICA) in each modality separately. Then the interactions among FNs in each modality are explored by Granger causality analysis (GCA). Finally, fMRI FNs are matched to EEG FNs in the spatial domain using network-based source imaging (NESOI). Investigations of both synthetic and real data demonstrate that mFNC has the potential to reveal the underlying neural networks of each modality separately and in their combination. With mFNC, comprehensive relationships among FNs might be unveiled for the deep exploration of neural activities and metabolic responses in a specific task or neurological state
A MISSING-LINK IN THE SUPERNOVA-GRB CONNECTION: THE CASE OF SN 2012ap
Gamma Ray Bursts (GRBs) are characterized by ultra-relativistic outflows,
while supernovae are generally characterized by non-relativistic ejecta. GRB
afterglows decelerate rapidly usually within days, because their low-mass
ejecta rapidly sweep up a comparatively larger mass of circumstellar material.
However supernovae, with heavy ejecta, can be in nearly free expansion for
centuries. Supernovae were thought to have non-relativistic outflows except for
few relativistic ones accompanied by GRBs. This clear division was blurred by
SN 2009bb, the first supernova with a relativistic outflow without an observed
GRB. Yet the ejecta from SN 2009bb was baryon loaded, and in nearly-free
expansion for a year, unlike GRBs. We report the first supernova discovered
without a GRB, but with rapidly decelerating mildly relativistic ejecta, SN
2012ap. We discovered a bright and rapidly evolving radio counterpart driven by
the circumstellar interaction of the relativistic ejecta. However, we did not
find any coincident GRB with an isotropic fluence of more than a sixth of the
fluence from GRB 980425. This shows for the first time that central engines in
type Ic supernovae, even without an observed GRB, can produce both relativistic
and rapidly decelerating outflows like GRBs.Comment: 8 pages, 5 figures, 1 table, accepted for publication in Ap
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