1,681 research outputs found

    Chlamydia Hijacks ARF GTPases To Coordinate Microtubule Posttranslational Modifications and Golgi Complex Positioning.

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    The intracellular bacterium Chlamydia trachomatis develops in a parasitic compartment called the inclusion. Posttranslationally modified microtubules encase the inclusion, controlling the positioning of Golgi complex fragments around the inclusion. The molecular mechanisms by which Chlamydia coopts the host cytoskeleton and the Golgi complex to sustain its infectious compartment are unknown. Here, using a genetically modified Chlamydia strain, we discovered that both posttranslationally modified microtubules and Golgi complex positioning around the inclusion are controlled by the chlamydial inclusion protein CT813/CTL0184/InaC and host ARF GTPases. CT813 recruits ARF1 and ARF4 to the inclusion membrane, where they induce posttranslationally modified microtubules. Similarly, both ARF isoforms are required for the repositioning of Golgi complex fragments around the inclusion. We demonstrate that CT813 directly recruits ARF GTPases on the inclusion membrane and plays a pivotal role in their activation. Together, these results reveal that Chlamydia uses CT813 to hijack ARF GTPases to couple posttranslationally modified microtubules and Golgi complex repositioning at the inclusion.IMPORTANCEChlamydia trachomatis is an important cause of morbidity and a significant economic burden in the world. However, how Chlamydia develops its intracellular compartment, the so-called inclusion, is poorly understood. Using genetically engineered Chlamydia mutants, we discovered that the effector protein CT813 recruits and activates host ADP-ribosylation factor 1 (ARF1) and ARF4 to regulate microtubules. In this context, CT813 acts as a molecular platform that induces the posttranslational modification of microtubules around the inclusion. These cages are then used to reposition the Golgi complex during infection and promote the development of the inclusion. This study provides the first evidence that ARF1 and ARF4 play critical roles in controlling posttranslationally modified microtubules around the inclusion and that Chlamydia trachomatis hijacks this novel function of ARF to reposition the Golgi complex

    Intelligent Transportation Systems Strategic Plan (Phase I Report)

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    This interim report on an Intelligent Transportation Systems Strategic (ITS) Plan has been developed as documentation of the process of offering a vision for ITS and recommending an outline for organizational structure, infrastructure, and long-term planning for ITS in Kentucky. This plan provides an overview of the broad scope of ITS and relationships between various Intelligent Vehicle Highway Systems (IVHS) functional areas and ITS user service areas. Three of the functional areas of ITS have been addressed in this interim report with sections devoted to mission, vision, goals, and potential technology applications. Within each of the three areas, recommendations have been made for applications and technologies for deployment. A more formalized business plan for will be developed to recommend specific projects for implementation. Those three functional areas are 1) Advanced Rural Transportation Systems (ARTS), 2) Advanced Traveler Information Systems (ATIS), and 3) Commercial Vehicle Operations (CVO). A survey of other states was conducted to determine the status of the development of ITS strategic plans. Information received from the 11 states that had completed strategic plans was used to determine the overall approach taken in development of the plans and to evaluate the essential contents of the reports for application in Kentucky. Kentucky\u27s ITS Strategic Plan evolved from an early decision by representatives of the Kentucky Transportation Cabinet (KyTC) to formalize the procedure by requesting the Kentucky Transportation Center to prepare a work plan outlining the proposed tasks. Following several introductory meetings of the Study Advisory Committee, additional focus group meetings were held with various transportation representatives to identify ITS issues of importance. Results from these meetings were compiled and used as input to the planning process for development of the Strategic Plan components of ARTS and ATIS. The development of a strategic plan for Commercial Vehicle Operations originated from a different procedure than did the other functional areas of ITS. As part of well-developed commercial vehicle activities through the ITS-related programs of Advantage I-75 and CVISN, Kentucky has become a national leader in this area and has developed a strategic plan of advanced technology applications to commercial vehicles. The strategic plan for Commercial Vehicle Operations was developed out of the convergence of several parallel processes in Kentucky. Empower Kentucky work teams had met over a two-year period to develop improved and more efficient processes for CVO in Kentucky. Their conclusions and recommendations encouraged the further activities of the Kentucky ITS/CVO working group that first convened in the summer of 1996. In an effort to conceptually organize the various ITS/CVO activities in Kentucky, and as a commitment to the CVISN Mainstreaming plan, an inclusive visioning exercise was held in early 1997. Out of this exercise emerged the six critical vision elements that guided the CVO strategic plan. The remaining functional areas to be included in the ITS Strategic Plan will be addressed in the second phase of this study. Those areas are Advanced Traffic Management Systems (ATMS), Advanced Vehicle Control Systems (AVCS), and Advanced Public Transportation Systems (APTS). It is anticipated that a process similar to that developed for the first phase of this study will continue

    Constructing futures: a social constructionist perspective on foresight methodology

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    The aim of this paper is to demonstrate the relationship between a particular epistemological perspective and foresight methodology. We draw on a body of social theory concerned with the way that meaning is produced and assimilated by society; specifically, the social construction of knowledge, which is distinguished from its nearneighbour constructivism by its focus on inter-subjectivity. We show that social constructionism, at least in its weak form, seems to be implicit in many epistemological assumptions underlying futures studies. We identify a range of distinctive methodological features in foresight studies, such as time, descriptions of difference, participation and values, and examine these from a social constructionist perspective. It appears that social constructionism is highly resonant with the way in which knowledge of the future is produced and used. A social constructionism perspective enables a methodological reflection on how, with what legitimacy, and to what social good, knowledge is produced. Foresight that produces symbols without inter-subjective meaning neither anticipates, nor produces futures. Our conclusion is that foresight is both a social construction, and a mechanism for social construction. Methodologically, foresight projects should acknowledge the socially constructed nature of their process and outcomes as this will lead to greater rigour and legitimacy

    Design and development of MOSFIRE: the Multi-Object Spectrometer For Infra-Red Exploration at the Keck Observatory

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    MOSFIRE is a unique multi-object spectrometer and imager for the Cassegrain focus of the 10 m Keck 1 telescope. A refractive optical design provides near-IR (0.97 to 2.45 μm) multi-object spectroscopy over a 6.14' x 6.14' field of view with a resolving power of R~3,270 for a 0.7" slit width (2.9 pixels in the dispersion direction), or imaging over a field of view of 6.8' diameter with 0.18" per pixel sampling. A single diffraction grating can be set at two fixed angles, and order-sorting filters provide spectra that cover the K, H, J or Y bands by selecting 3rd, 4th, 5th or 6th order respectively. A folding flat following the field lens is equipped with piezo transducers to provide tip/tilt control for flexure compensation at the 0.1 pixel level. A special feature of MOSFIRE is that its multiplex advantage of up to 46 slits is achieved using a cryogenic Configurable Slit Unit or CSU developed in collaboration with the Swiss Centre for Electronics and Micro Technology (CSEM). The CSU is reconfigurable under remote control in less than 5 minutes without any thermal cycling of the instrument. Slits are formed by moving opposable bars from both sides of the focal plane. An individual slit has a length of 7.1" but bar positions can be aligned to make longer slits. When masking bars are removed to their full extent and the grating is changed to a mirror, MOSFIRE becomes a wide-field imager. Using a single, ASIC-driven, 2K x 2K H2-RG HgCdTe array from Teledyne Imaging Sensors with exceptionally low dark current and low noise, MOSFIRE will be extremely sensitive and ideal for a wide range of science applications. This paper describes the design and testing of the instrument prior to delivery later in 2010

    The flux qubit revisited to enhance coherence and reproducibility

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    The scalable application of quantum information science will stand on reproducible and controllable high-coherence quantum bits (qubits). Here, we revisit the design and fabrication of the superconducting flux qubit, achieving a planar device with broad-frequency tunability, strong anharmonicity, high reproducibility and relaxation times in excess of 40 μs at its flux-insensitive point. Qubit relaxation times T₁ across 22 qubits are consistently matched with a single model involving resonator loss, ohmic charge noise and 1/f-flux noise, a noise source previously considered primarily in the context of dephasing. We furthermore demonstrate that qubit dephasing at the flux-insensitive point is dominated by residual thermal-photons in the readout resonator. The resulting photon shot noise is mitigated using a dynamical decoupling protocol, resulting in T₂≈85 μs, approximately the 2T₁ limit. In addition to realizing an improved flux qubit, our results uniquely identify photon shot noise as limiting T₂ in contemporary qubits based on transverse qubit–resonator interaction

    The Florence Statement on Triclosan and Triclocarban

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    The Florence Statement on Triclosan and Triclocarban documents a consensus of more than 200 scientists and medical professionals on the hazards of and lack of demonstrated benefit from common uses of triclosan and triclocarban. These chemicals may be used in thousands of personal care and consumer products as well as in building materials. Based on extensive peer-reviewed research, this statement concludes that triclosan and triclocarban are environmentally persistent endocrine disruptors that bioaccumulate in and are toxic to aquatic and other organisms. Evidence of other hazards to humans and ecosystems from triclosan and triclocarban is presented along with recommendations intended to prevent future harm from triclosan, triclocarban, and antimicrobial substances with similar properties and effects. Because antimicrobials can have unintended adverse health and environmental impacts, they should only be used when they provide an evidence-based health benefit. Greater transparency is needed in product formulations, and before an antimicrobial is incorporated into a product, the long-term health and ecological impacts should be evaluated

    Language, Religion, and Ethnic Civil War

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    Are certain ethnic cleavages more conflict-prone than others? While only few scholars focus on the contents of ethnicity, most of those who do argue that political violence is more likely to occur along religious divisions than linguistic ones. We challenge this claim by analyzing the path from linguistic differences to ethnic civil war along three theoretical steps: (1) the perception of grievances by group members, (2) rebel mobilization, and (3) government accommodation of rebel demands. Our argument is tested with a new data set of ethnic cleavages that records multiple linguistic and religious segments for ethnic groups from 1946 to 2009. Adopting a relational perspective, we assess ethnic differences between potential challengers and the politically dominant group in each country. Our findings indicate that intrastate conflict is more likely within linguistic dyads than among religious ones. Moreover, we find no support for the thesis that Muslim groups are particularly conflict-prone

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

    Stretching the IR theoretical spectrum on Irish neutrality: a critical social constructivist framework

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    In a 2006 International Political Science Review article, entitled "Choosing to Go It Alone: Irish Neutrality in Theoretical and Comparative Perspective," Neal G. Jesse argues that Irish neutrality is best understood through a neoliberal rather than a neorealist international relations theory framework. This article posits an alternative "critical social constructivist" framework for understanding Irish neutrality. The first part of the article considers the differences between neoliberalism and social constructivism and argues why critical social constructivism's emphasis on beliefs, identity, and the agency of the public in foreign policy are key factors explaining Irish neutrality today. Using public opinion data, the second part of the article tests whether national identity, independence, ethnocentrism, attitudes to Northern Ireland, and efficacy are factors driving public support for Irish neutrality. The results show that public attitudes to Irish neutrality are structured along the dimensions of independence and identity, indicating empirical support for a critical social constructivist framework of understanding of Irish neutrality
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