Science.gov

Sample records for accessible conformational space

  1. Mapping the conformational space accessible to catechol-O-methyltransferase

    PubMed Central

    Ehler, Andreas; Benz, Jörg; Schlatter, Daniel; Rudolph, Markus G.

    2014-01-01

    Methylation catalysed by catechol-O-methyltransferase (COMT) is the main pathway of catechol neurotransmitter deactivation in the prefrontal cortex. Low levels of this class of neurotransmitters are held to be causative of diseases such as schizophrenia, depression and Parkinson’s disease. Inhibition of COMT may increase neurotransmitter levels, thus offering a route for treatment. Structure-based drug design hitherto seems to be based on the closed enzyme conformation. Here, a set of apo, semi-holo, holo and Michaelis form crystal structures are described that define the conformational space available to COMT and that include likely intermediates along the catalytic pathway. Domain swaps and sizeable loop movements around the active site testify to the flexibility of this enzyme, rendering COMT a difficult drug target. The low affinity of the co-substrate S-adenosylmethionine and the large conformational changes involved during catalysis highlight significant energetic investment to achieve the closed conformation. Since each conformation of COMT is a bona fide target for inhibitors, other states than the closed conformation may be promising to address. Crystallographic data for an alternative avenue of COMT inhibition, i.e. locking of the apo state by an inhibitor, are presented. The set of COMT structures may prove to be useful for the development of novel classes of inhibitors. PMID:25084335

  2. Mapping the conformational space accessible to BACE2 using surface mutants and cocrystals with Fab fragments, Fynomers and Xaperones.

    PubMed

    Banner, David W; Gsell, Bernard; Benz, Jörg; Bertschinger, Julian; Burger, Dominique; Brack, Simon; Cuppuleri, Simon; Debulpaep, Maja; Gast, Alain; Grabulovski, Dragan; Hennig, Michael; Hilpert, Hans; Huber, Walter; Kuglstatter, Andreas; Kusznir, Eric; Laeremans, Toon; Matile, Hugues; Miscenic, Christian; Rufer, Arne C; Schlatter, Daniel; Steyaert, Jan; Stihle, Martine; Thoma, Ralf; Weber, Martin; Ruf, Armin

    2013-06-01

    The aspartic protease BACE2 is responsible for the shedding of the transmembrane protein Tmem27 from the surface of pancreatic β-cells, which leads to inactivation of the β-cell proliferating activity of Tmem27. This role of BACE2 in the control of β-cell maintenance suggests BACE2 as a drug target for diabetes. Inhibition of BACE2 has recently been shown to lead to improved control of glucose homeostasis and to increased insulin levels in insulin-resistant mice. BACE2 has 52% sequence identity to the well studied Alzheimer's disease target enzyme β-secretase (BACE1). High-resolution BACE2 structures would contribute significantly to the investigation of this enzyme as either a drug target or anti-target. Surface mutagenesis, BACE2-binding antibody Fab fragments, single-domain camelid antibody VHH fragments (Xaperones) and Fyn-kinase-derived SH3 domains (Fynomers) were used as crystallization helpers to obtain the first high-resolution structures of BACE2. Eight crystal structures in six different packing environments define an ensemble of low-energy conformations available to the enzyme. Here, the different strategies used for raising and selecting BACE2 binders for cocrystallization are described and the crystallization success, crystal quality and the time and resources needed to obtain suitable crystals are compared.

  3. Access to space study

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This report summarizes the results of a comprehensive NASA in-house study to identify and assess alternate approaches to access to space through the year 2030, and to select and recommend a preferred cause of action. The goals of the study were to identify the best vehicles and transportation architectures to make major reductions in the cost of space transportation (at least 50%), while at the same time increasing safety for flight crews by at least an order of magnitude. In addition, vehicle reliability was to exceed 0.98 percent, and, as important, the robustness, pad time, turnaround time, and other aspects of operability were to be vastly improved. This study examined three major optional architectures: (1) retain and upgrade the Space Shuttle and expendable launch vehicles; (2) develop new expendable vehicles using conventional technologies and transition from current vehicles beginning in 2005; and (3) develop new reusable vehicles using advanced technology, and transition from current vehicles beginning in 2008. The launch-needs, mission model utilized for for the study was based upon today's projection of civil, defense, and commercial mission payload requirements.

  4. Conformal Bootstrap in Mellin Space

    NASA Astrophysics Data System (ADS)

    Gopakumar, Rajesh; Kaviraj, Apratim; Sen, Kallol; Sinha, Aninda

    2017-02-01

    We propose a new approach towards analytically solving for the dynamical content of conformal field theories (CFTs) using the bootstrap philosophy. This combines the original bootstrap idea of Polyakov with the modern technology of the Mellin representation of CFT amplitudes. We employ exchange Witten diagrams with built-in crossing symmetry as our basic building blocks rather than the conventional conformal blocks in a particular channel. Demanding consistency with the operator product expansion (OPE) implies an infinite set of constraints on operator dimensions and OPE coefficients. We illustrate the power of this method in the ɛ expansion of the Wilson-Fisher fixed point by reproducing anomalous dimensions and, strikingly, obtaining OPE coefficients to higher orders in ɛ than currently available using other analytic techniques (including Feynman diagram calculations). Our results enable us to get a somewhat better agreement between certain observables in the 3D Ising model and the precise numerical values that have been recently obtained.

  5. Access Nets: Modeling Access to Physical Spaces

    NASA Astrophysics Data System (ADS)

    Frohardt, Robert; Chang, Bor-Yuh Evan; Sankaranarayanan, Sriram

    Electronic, software-managed mechanisms using, for example, radio-frequency identification (RFID) cards, enable great flexibility in specifying access control policies to physical spaces. For example, access rights may vary based on time of day or could differ in normal versus emergency situations. With such fine-grained control, understanding and reasoning about what a policy permits becomes surprisingly difficult requiring knowledge of permission levels, spatial layout, and time. In this paper, we present a formal modeling framework, called AccessNets, suitable for describing a combination of access permissions, physical spaces, and temporal constraints. Furthermore, we provide evidence that model checking techniques are effective in reasoning about physical access control policies. We describe our results from a tool that uses reachability analysis to validate security policies.

  6. Astronauts Access Web from Space

    NASA Video Gallery

    Aboard the International Space Station, Expedition 22 Commander Jeff Williams and Flight Engineers Soichi Noguchi and T.J. Creamer share their thoughts about Internet access from space and post a r...

  7. Affine conformal vectors in space-time

    NASA Astrophysics Data System (ADS)

    Coley, A. A.; Tupper, B. O. J.

    1992-05-01

    All space-times admitting a proper affine conformal vector (ACV) are found. By using a theorem of Hall and da Costa, it is shown that such space-times either (i) admit a covariantly constant vector (timelike, spacelike, or null) and the ACV is the sum of a proper affine vector and a conformal Killing vector or (ii) the space-time is 2+2 decomposable, in which case it is shown that no ACV can exist (unless the space-time decomposes further). Furthermore, it is proved that all space-times admitting an ACV and a null covariantly constant vector (which are necessarily generalized pp-wave space-times) must have Ricci tensor of Segré type {2,(1,1)}. It follows that, among space-times admitting proper ACV, the Einstein static universe is the only perfect fluid space-time, there are no non-null Einstein-Maxwell space-times, and only the pp-wave space-times are representative of null Einstein-Maxwell solutions. Otherwise, the space-times can represent anisotropic fluids and viscous heat-conducting fluids, but only with restricted equations of state in each case.

  8. Securing America's access to space

    SciTech Connect

    Rendine, M.; Wood, L.

    1990-05-23

    We review pertinent aspects of the history of the space launch capabilities of the United States and survey its present status and near-term outlook. Steps which must be taken, pitfalls which much be avoided, and a core set of National options for re-acquiring in the near term the capability to access the space environment with large payloads are discussed. We devote considerable attention to the prospect of creating an interim heavy-lift space launch vehicle of at least 100,000 pound payload-orbiting capacity to serve National needs during the next dozen years, suggesting that such a capability can be demonstrated within 5 years for less than $1 B. Such capability will apparently be essential for meeting the first-phase goals of the President's Space Exploration Initiative. Some other high-leverage aspects of securing American access to space are also noted briefly, emphasizing unconventional technological approaches of presently high promise.

  9. NASA studies access to space

    NASA Technical Reports Server (NTRS)

    Bekey, Ivan; Powell, Richard; Austin, Robery

    1994-01-01

    A comprehensive internal NASA study known as 'Access to Space' has sought to identify and assess major alternatives for the long-range direction the space transportation program should take. The scope of the study covered all U.S. civilian, commercial, and national security needs for space transportation for the next several decades. Three alternative approaches were identified: using current vehicles; developing new conventional technology vehicles, and developing new advanced technology vehicles. Large annual operations cost savings could be obtained only with new vehicles, and then only with considerable up-front investments. Seven other major factors were assessed. The third option is found to be the most attractive.

  10. Double conformal space-time algebra

    NASA Astrophysics Data System (ADS)

    Easter, Robert Benjamin; Hitzer, Eckhard

    2017-01-01

    The Double Conformal Space-Time Algebra (DCSTA) is a high-dimensional 12D Geometric Algebra G 4,8that extends the concepts introduced with the Double Conformal / Darboux Cyclide Geometric Algebra (DCGA) G 8,2 with entities for Darboux cyclides (incl. parabolic and Dupin cyclides, general quadrics, and ring torus) in spacetime with a new boost operator. The base algebra in which spacetime geometry is modeled is the Space-Time Algebra (STA) G 1,3. Two Conformal Space-Time subalgebras (CSTA) G 2,4 provide spacetime entities for points, flats (incl. worldlines), and hyperbolics, and a complete set of versors for their spacetime transformations that includes rotation, translation, isotropic dilation, hyperbolic rotation (boost), planar reflection, and (pseudo)spherical inversion in rounds or hyperbolics. The DCSTA G 4,8 is a doubling product of two G 2,4 CSTA subalgebras that inherits doubled CSTA entities and versors from CSTA and adds new bivector entities for (pseudo)quadrics and Darboux (pseudo)cyclides in spacetime that are also transformed by the doubled versors. The "pseudo" surface entities are spacetime hyperbolics or other surface entities using the time axis as a pseudospatial dimension. The (pseudo)cyclides are the inversions of (pseudo)quadrics in rounds or hyperbolics. An operation for the directed non-uniform scaling (anisotropic dilation) of the bivector general quadric entities is defined using the boost operator and a spatial projection. DCSTA allows general quadric surfaces to be transformed in spacetime by the same complete set of doubled CSTA versor (i.e., DCSTA versor) operations that are also valid on the doubled CSTA point entity (i.e., DCSTA point) and the other doubled CSTA entities. The new DCSTA bivector entities are formed by extracting values from the DCSTA point entity using specifically defined inner product extraction operators. Quadric surface entities can be boosted into moving surfaces with constant velocities that display the length

  11. Access to space: The Space Shuttle's evolving rolee

    NASA Astrophysics Data System (ADS)

    Duttry, Steven R.

    1993-04-01

    Access to space is of extreme importance to our nation and the world. Military, civil, and commercial space activities all depend on reliable space transportation systems for access to space at a reasonable cost. The Space Transportation System or Space Shuttle was originally planned to provide transportation to and from a manned Earth-orbiting space station. To justify the development and operations costs, the Space Shuttle took on other space transportation requirements to include DoD, civil, and a growing commercial launch market. This research paper or case study examines the evolving role of the Space Shuttle as our nation's means of accessing space. The case study includes a review of the events leading to the development of the Space Shuttle, identifies some of the key players in the decision-making process, examines alternatives developed to mitigate the risks associated with sole reliance on the Space Shuttle, and highlights the impacts of this national space policy following the Challenger accident.

  12. On the local non-conforming virtual element spaces

    SciTech Connect

    Manzini, Gianmarco; Gyrya, Vitaliy

    2014-11-13

    The construction of the local non-conforming virtual element spaces is discussed and the isomorphism between their functions and the polynomial moments of such functions is established by a formal argument and two different constructive proofs.

  13. Small Satellite Access of the Space Network

    NASA Technical Reports Server (NTRS)

    Horan, Stephen; Minnix, Timothy O.; Vigil, J. S.

    1999-01-01

    Small satellites have been perceived as having limited access to NASA's Space Network (SN). The potential for satellite access of the space network when the design utilizes a fixed antenna configuration and low-power, coded transmission is analyzed. From the analysis, satellites using this configuration in high-inclination orbits are shown to have a daily data throughput in the 100 to 1000 Mbit range using the multiple access communications service.

  14. Multinational Experiment 7: Protecting Access to Space

    DTIC Science & Technology

    2013-07-08

    be done to minimise the effects of disruption or a denial of access to space ?  Chapter 2: Space defence  Chapter 2: Collaborative space ...hazards and threats. So, we must adopt new strategies to assure necessary space capabilities. These strategies must be proactive, and develop the...influence an actor in space . Actor profile Possible actor courses of action Actor desirability analysis Modifying desirability Acceptable

  15. Exploring perturbative conformal field theory in Mellin space

    NASA Astrophysics Data System (ADS)

    Nizami, Amin A.; Rudra, Arnab; Sarkar, Sourav; Verma, Mritunjay

    2017-01-01

    We explore the Mellin representation of correlation functions in conformal field theories in the weak coupling regime. We provide a complete proof for a set of Feynman rules to write the Mellin amplitude for a general tree level Feynman diagram involving only scalar operators. We find a factorised form involving beta functions associated to the propagators, similar to tree level Feynman rules in momentum space for ordinary QFTs. We also briefly consider the case where a generic scalar perturbation of the free CFT breaks conformal invariance. Mellin space still has some utility and one can consider non-conformal Mellin representations. In this context, we find that the beta function corresponding to conformal propagator uplifts to a hypergeometric function.

  16. Twisted conformal algebra related to κ -Minkowski space

    NASA Astrophysics Data System (ADS)

    Meljanac, Stjepan; Pachoł, Anna; Pikutić, Danijel

    2015-11-01

    Twisted deformations of the conformal symmetry in the Hopf algebraic framework are constructed. The first one is obtained by a Jordanian twist built up from dilatation and momenta generators. The second is the lightlike κ -deformation of the Poincaré algebra extended to the conformal algebra, obtained by a twist corresponding to the extended Jordanian r -matrix. The κ -Minkowski spacetime is covariant quantum space under both of these deformations. The extension of the conformal algebra by the noncommutative coordinates is presented in two cases. The differential realizations for κ -Minkowski coordinates, as well as their left-right dual counterparts, are also included.

  17. Efficient algorithms to explore conformation spaces of flexible protein loops.

    PubMed

    Yao, Peggy; Dhanik, Ankur; Marz, Nathan; Propper, Ryan; Kou, Charles; Liu, Guanfeng; van den Bedem, Henry; Latombe, Jean-Claude; Halperin-Landsberg, Inbal; Altman, Russ Biagio

    2008-01-01

    Several applications in biology - e.g., incorporation of protein flexibility in ligand docking algorithms, interpretation of fuzzy X-ray crystallographic data, and homology modeling - require computing the internal parameters of a flexible fragment (usually, a loop) of a protein in order to connect its termini to the rest of the protein without causing any steric clash. One must often sample many such conformations in order to explore and adequately represent the conformational range of the studied loop. While sampling must be fast, it is made difficult by the fact that two conflicting constraints - kinematic closure and clash avoidance - must be satisfied concurrently. This paper describes two efficient and complementary sampling algorithms to explore the space of closed clash-free conformations of a flexible protein loop. The "seed sampling" algorithm samples broadly from this space, while the "deformation sampling" algorithm uses seed conformations as starting points to explore the conformation space around them at a finer grain. Computational results are presented for various loops ranging from 5 to 25 residues. More specific results also show that the combination of the sampling algorithms with a functional site prediction software (FEATURE) makes it possible to compute and recognize calcium-binding loop conformations. The sampling algorithms are implemented in a toolkit (LoopTK), which is available at https://simtk.org/home/looptk.

  18. Enhancing Access to Space Science Literature

    NASA Astrophysics Data System (ADS)

    Bigwood, D. P.

    2006-03-01

    By participating in the Name Authority Program Component and Subject Authority Cooperative Program of the Program for Cooperative Cataloging of the Library of Congress even the smallest libraries can enhance access to the space science literature.

  19. Fast Access to Space Tourism

    NASA Astrophysics Data System (ADS)

    Favata', P.; Martineau, N.

    2002-01-01

    creating a revolutionary space-orbiting habitat dedicated to tourism. Up to now, such proposals have focused on two approaches. The first accounts for financial and technological constraints on space flight and living, and sacrifices creativity for practicality. The second is more utopic in nature and proposes projects, which are imaginative but unfeasible in the near future. This proposal is innovative because it considers the current obstacles to space tourism and utilizes existing technologies and infrastructures, but also includes the forethinking of futuristic commercial projects. Project Objectives: NASA claims that commercialization of space activities is so difficult that it will require decades more funding of so-called space-technology development. The benefits of this project show that this is not true. First, safety has been addressed because this proposal utilizes already space tested and assured technologies. Second, the project demonstrates potential for significant economic profit within the near future. Because we are using the least expensive technology available, we have limited start up costs. We forecast up to forty flights per year, with a potential capacity of eighty tourists. The design objectives focus on the proposal of a new approach to space tourism. These include: the expansion of the living space in the interiors, innovative and creative interior design, increased concern for the physiological and psychological comfort of tourists, and attention to entertainment possibilities. Project Content: The efficiency of the launch and configuration phase is one of the strengths of the proposed project. We propose the use of the Zenith 2 launcher, a large two-stage vehicle developed in the Soviet Union in the early 1980s, for the configuration of the orbiting platform. Following the Russian outfitting philosophy, once in orbit, the platform is already functional. The interior design is based on advanced lightweight inflatable technologies which

  20. Technologies for affordable access to space

    NASA Technical Reports Server (NTRS)

    Colladay, R. S.; Sadin, S. R.

    1986-01-01

    NASA plans for advanced research and technology programs aimed at reducing operating costs and extending the capability of future space systems are described. The evolution of an almost entirely space-based mode is discussed, including the role of earth launch, servicing, fabrication and assembly and communications. The development of technology for affordable access to space is examined, taking into account progress in the areas of telerobotics, machine autonomy, human autonomy, space-based manufacturing and construction, electric power, and space-based propulsion.

  1. Access to Space Interactive Design Web Site

    NASA Technical Reports Server (NTRS)

    Leon, John; Cutlip, William; Hametz, Mark

    2000-01-01

    The Access To Space (ATS) Group at NASA's Goddard Space Flight Center (GSFC) supports the science and technology community at GSFC by facilitating frequent and affordable opportunities for access to space. Through partnerships established with access mode suppliers, the ATS Group has developed an interactive Mission Design web site. The ATS web site provides both the information and the tools necessary to assist mission planners in selecting and planning their ride to space. This includes the evaluation of single payloads vs. ride-sharing opportunities to reduce the cost of access to space. Features of this site include the following: (1) Mission Database. Our mission database contains a listing of missions ranging from proposed missions to manifested. Missions can be entered by our user community through data input tools. Data is then accessed by users through various search engines: orbit parameters, ride-share opportunities, spacecraft parameters, other mission notes, launch vehicle, and contact information. (2) Launch Vehicle Toolboxes. The launch vehicle toolboxes provide the user a full range of information on vehicle classes and individual configurations. Topics include: general information, environments, performance, payload interface, available volume, and launch sites.

  2. Global Trends in Space Access and Utilization

    NASA Technical Reports Server (NTRS)

    Rahman, Shamim A.; Keim, Nicholas S.; Zeender, Peter E.

    2010-01-01

    In the not-so-distant past, space access and air/space technology superiority were within the purview of the U.S. and former Soviet Union's respective space agencies, both vying for global leadership in space exploitation. In more recent years, with the emergence of the European Space Agency (ESA) member countries and Asian countries joining the family of space-faring nations, it is truer now more than ever that space access and utilization has become a truly global enterprise. In fact, according to the Space Report 2007, this enterprise is a $251-billion economy. It is possible to gauge the vitality of worldwide efforts from open sources in today's transparent, media-based society. In particular, print and web broadcasters regularly report and catalog global space activities for defense and civil purposes. For the purposes of this paper, a representative catalog of missions is used to illustrate the nature of the emerging "globalization." This paper highlights global trends in terms of not only the providers of space access, but also the end-users for the various recently accomplished missions. With well over 50 launches per year, in recent years, the launch-log reveals a surprising percentage of "cooperative or co-dependent missions" where different agencies, countries, and/or commercial entities are so engaged presumably to the benefit of all who participate. Statistics are cited and used to show that recently over d0% of the 50-plus missions involved multiple nations working collectively to deliver payloads to orbit. Observers, space policy professionals, and space agency leaders have eloquently proposed that it might require the combined resources and talents of multiple nations to advance human exploration goals beyond low earth orbit. This paper does not intend to offer new information with respect to whether international collaboration is necessary but to observe that, in continuing to monitor global trends, the results seem to support the thesis that a

  3. CASH 2021: commercial access and space habitation.

    PubMed

    Aldrin, Andrew; Amara, Adam; Aris, Lodewijk; Baierl, Nida; Beatty, Patrick; Beaulieu, Catherine; Behnke, Torsten; Castegini, Roberta; Chauhan, Amitabh; Cojanis, Philip; Dayawansa, Pelawa; Diop, Marie; Eito, Kinya; Engle, Steve; Feretti, Stefano; Gassama, Hamet; Genova, Bojana; Goulding, Colin; Janjua, Jameel; Jansaeng, Thidarat; Jousset, Frederic; Kopik, Anatoly; Laurin, Catherine; Leggatt, Jason; Li, Hengnian; Mezzadri, Monica; Miura, Amane; Nolet, Simon; Ogami, Satoshi; Patry, Johanne; Patten, Laryssa; Payerne, Cyril; Peer, Guy; Prampolini, Marco; Rheaume, Caroline; Saary, Joan; Spehar, Daniela; Sufi, Atiya; Sun, Baosheng; Thompson, J Barry; Thomson, Ward; Trautner, Roland; Tursunmuratov, Murat; Venet, Vrata; Wilems, Elizabeth; Wilson, Helen; Wittwer, Karl; Wokke, Frank; Wu, Yansheng; Zhou, Shaobin; Zilioli, Ilaria

    2002-01-01

    Issues about commercialization of space have been a growing concern in the past decade for the space community. This paper focuses on the work from a team of 51 students attending the Summer Session Program of the International Space University in Bremen, Germany. CASH 2021 (Commercial Access and Space Habitation) documents a plan that identifies commercial opportunities for space utilization that will extend human presence in space, and will chart the way forward for the next 20 years. The group selected four commercial sectors that show the most promise for the future: tourism, entertainment, space system service, assembly and debris removal, and research and development/production. The content of this document presents the results of their research. Historical activities in each of the commercial sectors are reviewed along with the current market situation. To provide a coherent background for future commercialization possibilities a scenario has been developed. This scenario includes a postulated upon ideal future and includes social, political and economic factors that may affect the space industry over the timeline of the study. The study also presents a roadmap, within the limited optimistic scenario developed, for the successful commercialization of space leading to future human presence in space. A broad range of commercially viable opportunities, not only within the current limits of the International Space Station, but also among the many new developments that are expected by 2021 are discussed.

  4. CASH 2021: Commercial access and space habitation

    NASA Astrophysics Data System (ADS)

    Aldrin, Andrew; Amara, Adam; Aris, Lodewijk; Baierl, Nida; Beatty, Patrick; Beaulieu, Catherine; Behnke, Torsten; Castegini, Roberta; Chauhan, Amitabh; Cojanis, Philip; Dayawansa, Pelawa; Diop, Marie; Eito, Kinya; Engle, Steve; Ferretti, Stefano; Gassama, Hamet; Genova, Bojana; Goulding, Colin; Janjua, Jameel; Jansaeng, Thidarat; Jousset, Frédéric; Kopik, Anatoly; Laurin, Catherine; Leggatt, Jason; Li, Hengnian; Mezzadri, Monica; Miura, Amane; Nolet, Simon; Ogami, Satoshi; Patry, Johanne; Patten, Laryssa; Payerne, Cyril; Peer, Guy; Prampolini, Marco; Rheaume, Caroline; Saary, Joan; Spehar, Daniela; Sufi, Atiya; Sun, Baosheng; Thompson, J. Barry; Thomson, Ward; Trautner, Roland; Tursunmuratov, Murat; Venet, Vrata; Wilems, Elizabeth; Wilson, Helen; Wittwer, Karl; Wokke, Frank; Wu, Yansheng; Zhou, Shaobin; Zilioli, Ilaria

    2002-07-01

    Issues about commercialization of space have been a growing concern in the past decade for the space community. This paper focuses on the work from a team of 51 students attending the Summer Session Program of the International Space University in Bremen, Germany. CASH 2021 (Commercial Access and Space Habitation) documents a plan that identifies commercial opportunities for space utilization that will extend human presence in space, and will chart the way forward for the next 20 years. The group selected four commercial sectors that show the most promise for the future: tourism, entertainment, space system service, assembly and debris removal, and research and development/production. The content of this document presents the results of their research. Historical activities in each of the commercial sectors are reviewed along with the current market situation. To provide a coherent background for future commercialization possibilities a scenario has been developed. This scenario includes a postulated upon ideal future and includes social, political and economic factors that may affect the space industry over the timeline of the study. The study also presents a roadmap, within the limited optimistic scenario developed, for the successful commercialization of space leading to future human presence in space. A broad range of commercially viable opportunities, not only within the current limits of the International Space Station, but also among the many new developments that are expected by 2021 are discussed.

  5. Cargo Assured Access to International Space Station

    NASA Technical Reports Server (NTRS)

    Smith, David A.

    2004-01-01

    Boeing's Cargo Assured Access logistics delivery system will provide a means to transport cargo to/from the International Space Station, Low Earth Orbit and the moon using Expendable Launch Vehicles. For Space Station, this capability will reduce cargo resupply backlog during nominal operations (e.g., supplement Shuttle, Progress, ATV and HTV) and augment cargo resupply capability during contingency operations (e.g., Shuttle delay and/or unavailability of International Partner launch or transfer vehicles). This capability can also provide an autonomous means to deliver cargo to lunar orbit, a lunar orbit refueling and work platform, and a contingency crew safe haven in support of NASA's new Exploration Initiative.

  6. A Demand Access Protocol for Space Applications

    NASA Technical Reports Server (NTRS)

    Gao, Jay L.; Leang, Dee

    2007-01-01

    This paper describes a demand access protocol for space communications, which is a messaging procedure that facilitates the exchange of resource requests and grants between users and service providers. A minimal set of operational and environmental needs and constraints are assumed since the intent is to keep the protocol flexible and efficient for a wide-range of envisioned NASA robotic and human exploration missions. The protocol described in this document defines the message format and procedures used to ensure proper and correct functioning of a demand access communications system, which must operate under customized resource management policies applied by the users and service providers. This protocol also assumes a minimal set of capabilities from the underlying communications system so that no unique requirements are imposed on the communications sub-systems.

  7. Stratospheric Balloon Platforms for Near Space Access

    NASA Astrophysics Data System (ADS)

    Dewey, R. G.

    2012-12-01

    For over five decades, high altitude aerospace balloon platforms have provided a unique vantage point for space and geophysical research by exposing scientific instrument packages and experiments to space-like conditions above 99% of Earth's atmosphere. Reaching altitudes in excess of 30 km for durations ranging from hours to weeks, high altitude balloons offer longer flight durations than both traditional sounding rockets and emerging suborbital reusable launch vehicles. For instruments and experiments requiring access to high altitudes, engineered balloon systems provide a timely, responsive, flexible, and cost-effective vehicle for reaching near space conditions. Moreover, high altitude balloon platforms serve as an early means of testing and validating hardware bound for suborbital or orbital space without imposing space vehicle qualifications and certification requirements on hardware in development. From float altitudes above 30 km visible obscuration of the sky is greatly reduced and telescopes and other sensors function in an orbit-like environment, but in 1g. Down-facing sensors can take long-exposure atmospheric measurements and images of Earth's surface from oblique and nadir perspectives. Payload support subsystems such as telemetry equipment and command, control, and communication (C3) interfaces can also be tested and operationally verified in this space-analog environment. For scientific payloads requiring over-flight of specific areas of interests, such as an active volcano or forest region, advanced mission planning software allows flight trajectories to be accurately modeled. Using both line-of-sight and satellite-based communication systems, payloads can be tracked and controlled throughout the entire mission duration. Under NASA's Flight Opportunities Program, NSC can provide a range of high altitude flight options to support space and geophysical research: High Altitude Shuttle System (HASS) - A balloon-borne semi-autonomous glider carries

  8. New conformations of linear polyubiquitin chains from crystallographic and solution-scattering studies expand the conformational space of polyubiquitin.

    PubMed

    Thach, Trung Thanh; Shin, Donghyuk; Han, Seungsu; Lee, Sangho

    2016-04-01

    The conformational flexibility of linkage-specific polyubiquitin chains enables ubiquitylated proteins and their receptors to be involved in a variety of cellular processes. Linear or Met1-linked polyubiquitin chains, associated with nondegradational cellular signalling pathways, have been known to adopt multiple conformations from compact to extended conformations. However, the extent of such conformational flexibility remains open. Here, the crystal structure of linear Ub2 was determined in a more compact conformation than that of the previously known structure (PDB entry 3axc). The two structures differ significantly from each other, as shown by an r.m.s.d. between C(α) atoms of 3.1 Å. The compactness of the linear Ub2 structure in comparison with PDB entry 3axc is supported by smaller values of the radius of gyration (Rg; 18 versus 18.9 Å) and the maximum interatomic distance (Dmax; 55.5 versus 57.8 Å). Extra intramolecular hydrogen bonds formed among polar residues between the distal and proximal ubiquitin moieties seem to contribute to stabilization of the compact conformation of linear Ub2. An ensemble of three semi-extended and extended conformations of linear Ub2 was also observed by small-angle X-ray scattering (SAXS) analysis in solution. In addition, the conformational heterogeneity in linear polyubiquitin chains is clearly manifested by SAXS analyses of linear Ub3 and Ub4: at least three distinct solution conformations are observed in each chain, with the linear Ub3 conformations being compact. The results expand the extent of conformational space of linear polyubiquitin chains and suggest that changes in the conformational ensemble may be pivotal in mediating multiple signalling pathways.

  9. Predictive Sampling of Rare Conformational Events in Aqueous Solution: Designing a Generalized Orthogonal Space Tempering Method.

    PubMed

    Lu, Chao; Li, Xubin; Wu, Dongsheng; Zheng, Lianqing; Yang, Wei

    2016-01-12

    In aqueous solution, solute conformational transitions are governed by intimate interplays of the fluctuations of solute-solute, solute-water, and water-water interactions. To promote molecular fluctuations to enhance sampling of essential conformational changes, a common strategy is to construct an expanded Hamiltonian through a series of Hamiltonian perturbations and thereby broaden the distribution of certain interactions of focus. Due to a lack of active sampling of configuration response to Hamiltonian transitions, it is challenging for common expanded Hamiltonian methods to robustly explore solvent mediated rare conformational events. The orthogonal space sampling (OSS) scheme, as exemplified by the orthogonal space random walk and orthogonal space tempering methods, provides a general framework for synchronous acceleration of slow configuration responses. To more effectively sample conformational transitions in aqueous solution, in this work, we devised a generalized orthogonal space tempering (gOST) algorithm. Specifically, in the Hamiltonian perturbation part, a solvent-accessible-surface-area-dependent term is introduced to implicitly perturb near-solute water-water fluctuations; more importantly in the orthogonal space response part, the generalized force order parameter is generalized as a two-dimension order parameter set, in which essential solute-solvent and solute-solute components are separately treated. The gOST algorithm is evaluated through a molecular dynamics simulation study on the explicitly solvated deca-alanine (Ala10) peptide. On the basis of a fully automated sampling protocol, the gOST simulation enabled repetitive folding and unfolding of the solvated peptide within a single continuous trajectory and allowed for detailed constructions of Ala10 folding/unfolding free energy surfaces. The gOST result reveals that solvent cooperative fluctuations play a pivotal role in Ala10 folding/unfolding transitions. In addition, our assessment

  10. Conformational dynamics of ligand-dependent alternating access in LeuT.

    PubMed

    Kazmier, Kelli; Sharma, Shruti; Quick, Matthias; Islam, Shahidul M; Roux, Benoît; Weinstein, Harel; Javitch, Jonathan A; McHaourab, Hassane S

    2014-05-01

    The leucine transporter (LeuT) from Aquifex aeolicus is a bacterial homolog of neurotransmitter/sodium symporters (NSSs) that catalyze reuptake of neurotransmitters at the synapse. Crystal structures of wild-type and mutants of LeuT have been interpreted as conformational states in the coupled transport cycle. However, the mechanistic identities inferred from these structures have not been validated, and the ligand-dependent conformational equilibrium of LeuT has not been defined. Here, we used distance measurements between spin-label pairs to elucidate Na(+)- and leucine-dependent conformational changes on the intracellular and extracellular sides of the transporter. The results identify structural motifs that underlie the isomerization of LeuT between outward-facing, inward-facing and occluded states. The conformational changes reported here present a dynamic picture of the alternating-access mechanism of LeuT and NSSs that is different from the inferences reached from currently available structural models.

  11. Ares Launch Vehicles Overview: Space Access Society

    NASA Technical Reports Server (NTRS)

    Cook, Steve

    2007-01-01

    America is returning to the Moon in preparation for the first human footprint on Mars, guided by the U.S. Vision for Space Exploration. This presentation will discuss NASA's mission, the reasons for returning to the Moon and going to Mars, and how NASA will accomplish that mission in ways that promote leadership in space and economic expansion on the new frontier. The primary goals of the Vision for Space Exploration are to finish the International Space Station, retire the Space Shuttle, and build the new spacecraft needed to return people to the Moon and go to Mars. The Vision commits NASA and the nation to an agenda of exploration that also includes robotic exploration and technology development, while building on lessons learned over 50 years of hard-won experience. NASA is building on common hardware, shared knowledge, and unique experience derived from the Apollo Saturn, Space Shuttle, and contemporary commercial launch vehicle programs. The journeys to the Moon and Mars will require a variety of vehicles, including the Ares I Crew Launch Vehicle, which transports the Orion Crew Exploration Vehicle, and the Ares V Cargo Launch Vehicle, which transports the Lunar Surface Access Module. The architecture for the lunar missions will use one launch to ferry the crew into orbit, where it will rendezvous with the Lunar Module in the Earth Departure Stage, which will then propel the combination into lunar orbit. The imperative to explore space with the combination of astronauts and robots will be the impetus for inventions such as solar power and water and waste recycling. This next chapter in NASA's history promises to write the next chapter in American history, as well. It will require this nation to provide the talent to develop tools, machines, materials, processes, technologies, and capabilities that can benefit nearly all aspects of life on Earth. Roles and responsibilities are shared between a nationwide Government and industry team. The Exploration Launch

  12. Making Space Science and Exploration Accessible

    NASA Astrophysics Data System (ADS)

    Runyon, C. J.; Guimond, K. A.; Hurd, D.; Heinrich, G.

    There are currently 28 million hard of hearing and deaf Americans, approximately 10 to 11 million blind and visually impaired people in North America, and more than 50 million Americans with disabilities, approximately half of whom are students. The majority of students with disabilities in the US are required to achieve the same academic levels as their non-impaired peers. Unfortunately, there are few specialized materials to help these exceptional students in the formal and informal settings. To assist educators in meeting their goals and engage the students, we are working with NASA product developers, scientists and education and outreach personnel in concert with teachers from exceptional classrooms to identify the types of materials they need and which mediums work best for the different student capabilities. Our goal is to make the wonders of space science and exploration accessible to all. As such, over the last four years we have been hosting interactive workshops, observing classroom settings, talking and working with professional educators, product developers, museum and science center personnel and parents to synthesize the most effective media and method for presenting earth and space science materials to audiences with exceptional needs. We will present a list of suggested best practices and example activities that can help engage and encourage a person with special needs to study the sciences, technology, engineering, and mathematics.

  13. National Report Norway: Arctic Access to Space

    NASA Astrophysics Data System (ADS)

    Brekke, P.

    2015-09-01

    Norway has long traditions as a space nation, much due to our northern latitude. Our space science activities are concentrated into relatively few areas. This concentration is necessary due to limited resources, both in funding and personnel. The main scientific activities are within Solar-terrestrial physics and cosmology. The first field has been a priority since before the space age and is still the major priority. The usage of the ground infrastructure in Northern Norway and on Svalbard is essential in studying the middle and upper atmosphere and the interaction with the Sun. This includes the utilization of sounding rockets, both small and large, and ground based installations like radars, lidars and other optical instrumentation. The planned use of Svalbard as a launch site for large stratospheric balloons may allow the cosmology community access to our northern infrastructure. The solar physics community is also heavily involved in the HINODE and IRIS missions and Norway is supporting downlink of data via the Svalbard Station for these missions. The sounding rocket program is in close collaboration with many countries like Germany, USA, France, Canada and Japan. Two scientific sounding rocket programs are currently being pursued: The ICI series (from Svalbard) and MaxiDusty (from Andoya). A series of scientific publications have recently appeared from the ECOMA campaign a few years ago. A significant improvement of today's polar and ionospheric research infrastructure in Northern Norway and Svalbard has recently been put on the ESFRI roadmap for European research infrastructure through the 5105 and EISCAT 3D initiatives. The Norwegian government has recently decided to upgrade the VLBI facilities at Svalbard.

  14. 29 CFR 1915.76 - Access to cargo spaces and confined spaces.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Access to cargo spaces and confined spaces. 1915.76 Section..., Ladders and Other Working Surfaces § 1915.76 Access to cargo spaces and confined spaces. The provisions of... this section applies to ship repairing only. (a) Cargo spaces. (1) There shall be at least one safe...

  15. 29 CFR 1915.76 - Access to cargo spaces and confined spaces.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Access to cargo spaces and confined spaces. 1915.76 Section..., Ladders and Other Working Surfaces § 1915.76 Access to cargo spaces and confined spaces. The provisions of... this section applies to ship repairing only. (a) Cargo spaces. (1) There shall be at least one safe...

  16. 29 CFR 1915.76 - Access to cargo spaces and confined spaces.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Access to cargo spaces and confined spaces. 1915.76 Section..., Ladders and Other Working Surfaces § 1915.76 Access to cargo spaces and confined spaces. The provisions of... this section applies to ship repairing only. (a) Cargo spaces. (1) There shall be at least one safe...

  17. 29 CFR 1915.76 - Access to cargo spaces and confined spaces.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Access to cargo spaces and confined spaces. 1915.76 Section..., Ladders and Other Working Surfaces § 1915.76 Access to cargo spaces and confined spaces. The provisions of... this section applies to ship repairing only. (a) Cargo spaces. (1) There shall be at least one safe...

  18. 29 CFR 1915.76 - Access to cargo spaces and confined spaces.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Access to cargo spaces and confined spaces. 1915.76 Section..., Ladders and Other Working Surfaces § 1915.76 Access to cargo spaces and confined spaces. The provisions of... this section applies to ship repairing only. (a) Cargo spaces. (1) There shall be at least one safe...

  19. Locally accessible conformations of proteins: multiple molecular dynamics simulations of crambin.

    PubMed Central

    Caves, L. S.; Evanseck, J. D.; Karplus, M.

    1998-01-01

    Multiple molecular dynamics (MD) simulations of crambin with different initial atomic velocities are used to sample conformations in the vicinity of the native structure. Individual trajectories of length up to 5 ns sample only a fraction of the conformational distribution generated by ten independent 120 ps trajectories at 300 K. The backbone atom conformational space distribution is analyzed using principal components analysis (PCA). Four different major conformational regions are found. In general, a trajectory samples only one region and few transitions between the regions are observed. Consequently, the averages of structural and dynamic properties over the ten trajectories differ significantly from those obtained from individual trajectories. The nature of the conformational sampling has important consequences for the utilization of MD simulations for a wide range of problems, such as comparisons with X-ray or NMR data. The overall average structure is significantly closer to the X-ray structure than any of the individual trajectory average structures. The high frequency (less than 10 ps) atomic fluctuations from the ten trajectories tend to be similar, but the lower frequency (100 ps) motions are different. To improve conformational sampling in molecular dynamics simulations of proteins, as in nucleic acids, multiple trajectories with different initial conditions should be used rather than a single long trajectory. PMID:9541397

  20. Efficient conformational space exploration in ab initio protein folding simulation

    PubMed Central

    Ullah, Ahammed; Ahmed, Nasif; Pappu, Subrata Dey; Shatabda, Swakkhar; Ullah, A. Z. M. Dayem; Rahman, M. Sohel

    2015-01-01

    Ab initio protein folding simulation largely depends on knowledge-based energy functions that are derived from known protein structures using statistical methods. These knowledge-based energy functions provide us with a good approximation of real protein energetics. However, these energy functions are not very informative for search algorithms and fail to distinguish the types of amino acid interactions that contribute largely to the energy function from those that do not. As a result, search algorithms frequently get trapped into the local minima. On the other hand, the hydrophobic–polar (HP) model considers hydrophobic interactions only. The simplified nature of HP energy function makes it limited only to a low-resolution model. In this paper, we present a strategy to derive a non-uniform scaled version of the real 20×20 pairwise energy function. The non-uniform scaling helps tackle the difficulty faced by a real energy function, whereas the integration of 20×20 pairwise information overcomes the limitations faced by the HP energy function. Here, we have applied a derived energy function with a genetic algorithm on discrete lattices. On a standard set of benchmark protein sequences, our approach significantly outperforms the state-of-the-art methods for similar models. Our approach has been able to explore regions of the conformational space which all the previous methods have failed to explore. Effectiveness of the derived energy function is presented by showing qualitative differences and similarities of the sampled structures to the native structures. Number of objective function evaluation in a single run of the algorithm is used as a comparison metric to demonstrate efficiency. PMID:26361554

  1. Efficient conformational space exploration in ab initio protein folding simulation.

    PubMed

    Ullah, Ahammed; Ahmed, Nasif; Pappu, Subrata Dey; Shatabda, Swakkhar; Ullah, A Z M Dayem; Rahman, M Sohel

    2015-08-01

    Ab initio protein folding simulation largely depends on knowledge-based energy functions that are derived from known protein structures using statistical methods. These knowledge-based energy functions provide us with a good approximation of real protein energetics. However, these energy functions are not very informative for search algorithms and fail to distinguish the types of amino acid interactions that contribute largely to the energy function from those that do not. As a result, search algorithms frequently get trapped into the local minima. On the other hand, the hydrophobic-polar (HP) model considers hydrophobic interactions only. The simplified nature of HP energy function makes it limited only to a low-resolution model. In this paper, we present a strategy to derive a non-uniform scaled version of the real 20×20 pairwise energy function. The non-uniform scaling helps tackle the difficulty faced by a real energy function, whereas the integration of 20×20 pairwise information overcomes the limitations faced by the HP energy function. Here, we have applied a derived energy function with a genetic algorithm on discrete lattices. On a standard set of benchmark protein sequences, our approach significantly outperforms the state-of-the-art methods for similar models. Our approach has been able to explore regions of the conformational space which all the previous methods have failed to explore. Effectiveness of the derived energy function is presented by showing qualitative differences and similarities of the sampled structures to the native structures. Number of objective function evaluation in a single run of the algorithm is used as a comparison metric to demonstrate efficiency.

  2. Exploration of conformational spaces of high-mannose-type oligosaccharides by an NMR-validated simulation.

    PubMed

    Yamaguchi, Takumi; Sakae, Yoshitake; Zhang, Ying; Yamamoto, Sayoko; Okamoto, Yuko; Kato, Koichi

    2014-10-06

    Exploration of the conformational spaces of flexible biomacromolecules is essential for quantitatively understanding the energetics of their molecular recognition processes. We employed stable isotope- and lanthanide-assisted NMR approaches in conjunction with replica-exchange molecular dynamics (REMD) simulations to obtain atomic descriptions of the conformational dynamics of high-mannose-type oligosaccharides, which harbor intracellular glycoprotein-fate determinants in their triantennary structures. The experimentally validated REMD simulation provided quantitative views of the dynamic conformational ensembles of the complicated, branched oligosaccharides, and indicated significant expansion of the conformational space upon removal of a terminal mannose residue during the functional glycan-processing pathway.

  3. 46 CFR 111.01-7 - Accessibility and spacing.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Accessibility and spacing. 111.01-7 Section 111.01-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-7 Accessibility and spacing. (a) The design and arrangement...

  4. 46 CFR 111.01-7 - Accessibility and spacing.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Accessibility and spacing. 111.01-7 Section 111.01-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS General § 111.01-7 Accessibility and spacing. (a) The design and arrangement...

  5. Conformational space and photochemistry of alpha-terpinene.

    PubMed

    Marzec, K M; Reva, I; Fausto, R; Malek, K; Proniewicz, L M

    2010-05-06

    Alpha-terpinene is a natural product that is isolated from a variety of plant sources and is used in the pharmaceutical and perfume industries. In the atmosphere, under the influence of sunlight, alpha-terpinene undergoes a series of photochemical transformations and contributes to the formation of the secondary organic aerosols. In the present work, alpha-terpinene has been isolated in low-temperature xenon and argon matrices, and its structure and photochemistry were characterized with the aid of FTIR spectroscopy and DFT calculations. The theory predicts three conformers resulting from the rotation of the exocyclic CH(CH(3))(2) framework, that is, Trans (T) and Gauche (G+ and G-) forms. The two Gauche conformers were estimated to be higher in energy, by ca. 1.75 kJ mol(-1), than the most stable Trans form. The signatures of all three conformers were found to be present in the experimental low-temperature matrix spectra with the T form dominating in diluted matrices. The conformational ratio was found to shift in favor of the G+/G- forms upon annealing of the matrices as well as in the neat alpha-terpinene liquid. UV-C (lambda > 235 nm) irradiation of matrix-isolated alpha-terpinene led to its isomerization into an open-ring species, which is produced in the Z configuration and in the conformations that require the smallest structural rearrangements of both the reagent and matrix.

  6. Pilot Non-Conformance to Alerting System Commands During Closely Spaced Parallel Approaches

    NASA Technical Reports Server (NTRS)

    Pritchett, Amy R.; Hansman, R. John

    1997-01-01

    Pilot non-conformance to alerting system commands has been noted in general and to a TCAS-like collision avoidance system in a previous experiment. This paper details two experiments studying collision avoidance during closely-spaced parallel approaches in instrument meteorological conditions (IMC), and specifically examining possible causal factors of, and design solutions to, pilot non-conformance.

  7. Acoustic omni meta-atom for decoupled access to all octants of a wave parameter space.

    PubMed

    Koo, Sukmo; Cho, Choonlae; Jeong, Jun-Ho; Park, Namkyoo

    2016-09-30

    The common behaviour of a wave is determined by wave parameters of its medium, which are generally associated with the characteristic oscillations of its corresponding elementary particles. In the context of metamaterials, the decoupled excitation of these fundamental oscillations would provide an ideal platform for top-down and reconfigurable access to the entire constitutive parameter space; however, this has remained as a conceivable problem that must be accomplished, after being pointed out by Pendry. Here by focusing on acoustic metamaterials, we achieve the decoupling of density ρ, modulus B(-1) and bianisotropy ξ, by separating the paths of particle momentum to conform to the characteristic oscillations of each macroscopic wave parameter. Independent access to all octants of wave parameter space (ρ, B(-1), ξ)=(+/-,+/-,+/-) is thus realized using a single platform that we call an omni meta-atom; as a building block that achieves top-down access to the target properties of metamaterials.

  8. Acoustic omni meta-atom for decoupled access to all octants of a wave parameter space

    PubMed Central

    Koo, Sukmo; Cho, Choonlae; Jeong, Jun-ho; Park, Namkyoo

    2016-01-01

    The common behaviour of a wave is determined by wave parameters of its medium, which are generally associated with the characteristic oscillations of its corresponding elementary particles. In the context of metamaterials, the decoupled excitation of these fundamental oscillations would provide an ideal platform for top–down and reconfigurable access to the entire constitutive parameter space; however, this has remained as a conceivable problem that must be accomplished, after being pointed out by Pendry. Here by focusing on acoustic metamaterials, we achieve the decoupling of density ρ, modulus B−1 and bianisotropy ξ, by separating the paths of particle momentum to conform to the characteristic oscillations of each macroscopic wave parameter. Independent access to all octants of wave parameter space (ρ, B−1, ξ)=(+/−,+/−,+/−) is thus realized using a single platform that we call an omni meta-atom; as a building block that achieves top–down access to the target properties of metamaterials. PMID:27687689

  9. A parallel systematic-Monte Carlo algorithm for exploring conformational space.

    PubMed

    Perez-Riverol, Yasset; Vera, Roberto; Mazola, Yuliet; Musacchio, Alexis

    2012-01-01

    Computational algorithms to explore the conformational space of small molecules are complex and computer demand field in chemoinformatics. In this paper a hybrid algorithm to explore the conformational space of organic molecules is presented. This hybrid algorithm is based in a systematic search approach combined with a Monte Carlo based method in order to obtain an ensemble of low-energy conformations simulating the flexibility of small chemical compounds. The Monte Carlo method uses the Metropolis criterion to accept or reject a conformation through an in-house implementation of the MMFF94s force field to calculate the conformational energy. The parallel design of this algorithm, based on the message passing interface (MPI) paradigm, was implemented. The results showed a performance increase in the terms of speed and efficiency.

  10. Transforming Community Access to Space Science Models

    NASA Technical Reports Server (NTRS)

    MacNeice, Peter; Heese, Michael; Kunetsova, Maria; Maddox, Marlo; Rastaetter, Lutz; Berrios, David; Pulkkinen, Antti

    2012-01-01

    Researching and forecasting the ever changing space environment (often referred to as space weather) and its influence on humans and their activities are model-intensive disciplines. This is true because the physical processes involved are complex, but, in contrast to terrestrial weather, the supporting observations are typically sparse. Models play a vital role in establishing a physically meaningful context for interpreting limited observations, testing theory, and producing both nowcasts and forecasts. For example, with accurate forecasting of hazardous space weather conditions, spacecraft operators can place sensitive systems in safe modes, and power utilities can protect critical network components from damage caused by large currents induced in transmission lines by geomagnetic storms.

  11. Exploring RNA conformational space under sparse distance restraints

    PubMed Central

    Taylor, William R.; Hamilton, Russell S.

    2017-01-01

    We show that the application of a small number of restraints predicted by coevolution analysis can provide a powerful restriction on the conformational freedom of an RNA molecule. The greatest degree of restriction occurs when a contact is predicted between the distal ends of a pair of adjacent stemloops but even with this location additional flexibilities in the molecule can mask the contribution. Multiple cross-links, especially those including a pseudoknot provided the strongest restraint on conformational freedom with the effect being most apparent in topologically simple folds and less so if the fold is more topologically entwined. Little was expected for large structures (over 300 bases) and although a few strong localised restrictions were observed, they contributed little to the restraint of the overall fold. Although contacts predicted using a correlated mutation analysis can provide some powerful restrictions on the conformational freedom of RNA molecules, they are too erratic in their occurrence and distribution to provide a general approach to the problem of RNA 3D structure prediction from sequence. PMID:28281575

  12. Exploring RNA conformational space under sparse distance restraints.

    PubMed

    Taylor, William R; Hamilton, Russell S

    2017-03-10

    We show that the application of a small number of restraints predicted by coevolution analysis can provide a powerful restriction on the conformational freedom of an RNA molecule. The greatest degree of restriction occurs when a contact is predicted between the distal ends of a pair of adjacent stemloops but even with this location additional flexibilities in the molecule can mask the contribution. Multiple cross-links, especially those including a pseudoknot provided the strongest restraint on conformational freedom with the effect being most apparent in topologically simple folds and less so if the fold is more topologically entwined. Little was expected for large structures (over 300 bases) and although a few strong localised restrictions were observed, they contributed little to the restraint of the overall fold. Although contacts predicted using a correlated mutation analysis can provide some powerful restrictions on the conformational freedom of RNA molecules, they are too erratic in their occurrence and distribution to provide a general approach to the problem of RNA 3D structure prediction from sequence.

  13. Complete maps of molecular-loop conformational spaces.

    PubMed

    Porta, Josep M; Ros, Lluís; Thomas, Federico; Corcho, Francesc; Cantó, Josep; Pérez, Juan Jesús

    2007-10-01

    This paper presents a numerical method to compute all possible conformations of distance-constrained molecular loops, i.e., loops where some interatomic distances are held fixed, while others can vary. The method is general (it can be applied to single or multiple intermingled loops of arbitrary topology) and complete (it isolates all solutions, even if they form positive-dimensional sets). Generality is achieved by reducing the problem to finding all embeddings of a set of points constrained by pairwise distances, which can be formulated as computing the roots of a system of Cayley-Menger determinants. Completeness is achieved by expressing these determinants in Bernstein form and using a numerical algorithm that exploits such form to bound all root locations at any desired precision. The method is readily parallelizable, and the current implementation can be run on single- or multiprocessor machines. Experiments are included that show the method's performance on rigid loops, mobile loops, and multiloop molecules. In all cases, complete maps including all possible conformations are obtained, thus allowing an exhaustive analysis and visualization of all pseudo-rotation paths between different conformations satisfying loop closure.

  14. 46 CFR 111.01-7 - Accessibility and spacing.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Accessibility and spacing. 111.01-7 Section 111.01-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... electric apparatus must afford accessibility to each part as needed to facilitate proper...

  15. 46 CFR 111.01-7 - Accessibility and spacing.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Accessibility and spacing. 111.01-7 Section 111.01-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... electric apparatus must afford accessibility to each part as needed to facilitate proper...

  16. 46 CFR 111.01-7 - Accessibility and spacing.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Accessibility and spacing. 111.01-7 Section 111.01-7 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... electric apparatus must afford accessibility to each part as needed to facilitate proper...

  17. Beamforming of joint polarization-space matched filtering for conformal array.

    PubMed

    Liu, Lutao; Jiang, Yilin; Wan, Liangtian; Tian, Zuoxi

    2013-01-01

    Due to the polarization mismatch of the antenna, the received signal suffers from energy loss. The conventional beamforming algorithms could not be applied to the conformal array because of the varying curvature. In order to overcome the energy loss of the received signal, a novel joint polarization-space matched filtering algorithm for cylindrical conformal array is proposed. First, the snapshot data model of the conformal polarization sensitive array is analyzed. Second, the analytical expression of polarization sensitive array beamforming is derived. Linearly constrained minimum variance (LCMV) beamforming technique is facilitated for the cylindrical conformal array. Third, the idea of joint polarization-space matched filtering is presented, and the principle of joint polarization-space matched filtering is discussed in detail. Theoretical analysis and computer simulation results verify that the conformal polarization sensitive array is more robust than the ordinary conformal array. The proposed algorithm can improve the performance when signal and interference are too close. It can enhance the signal-to-noise ratio (SNR) by adjusting the polarization of the elements of the conformal array, which matches the polarization of the incident signal.

  18. Euclidean sections of protein conformation space and their implications in dimensionality reduction.

    PubMed

    Duan, Mojie; Li, Minghai; Han, Li; Huo, Shuanghong

    2014-10-01

    Dimensionality reduction is widely used in searching for the intrinsic reaction coordinates for protein conformational changes. We find the dimensionality-reduction methods using the pairwise root-mean-square deviation (RMSD) as the local distance metric face a challenge. We use Isomap as an example to illustrate the problem. We believe that there is an implied assumption for the dimensionality-reduction approaches that aim to preserve the geometric relations between the objects: both the original space and the reduced space have the same kind of geometry, such as Euclidean geometry vs. Euclidean geometry or spherical geometry vs. spherical geometry. When the protein free energy landscape is mapped onto a 2D plane or 3D space, the reduced space is Euclidean, thus the original space should also be Euclidean. For a protein with N atoms, its conformation space is a subset of the 3N-dimensional Euclidean space R(3N). We formally define the protein conformation space as the quotient space of R(3N) by the equivalence relation of rigid motions. Whether the quotient space is Euclidean or not depends on how it is parameterized. When the pairwise RMSD is employed as the local distance metric, implicit representations are used for the protein conformation space, leading to no direct correspondence to a Euclidean set. We have demonstrated that an explicit Euclidean-based representation of protein conformation space and the local distance metric associated to it improve the quality of dimensionality reduction in the tetra-peptide and β-hairpin systems.

  19. On metric geometry of conformal moduli spaces of four-dimensional superconformal theories

    NASA Astrophysics Data System (ADS)

    Asnin, Vadim

    2010-09-01

    Conformal moduli spaces of four-dimensional superconformal theories obtained by deformations of a superpotential are considered. These spaces possess a natural metric (a Zamolodchikov metric). This metric is shown to be Kahler. The proof is based on superconformal Ward identities.

  20. System, cost, and risk analysis for access to space

    NASA Technical Reports Server (NTRS)

    Chase, James P.; Carter, Rebecca L.; Smith, Jeffrey L.

    2004-01-01

    This paper proposes the use of a new tool more quickly develop initial cost and risk estimates of alternative flight options for both single missions and the partnering of missions into a single space flight. this work is particularly useful for small missions that require low-cost opportunities for accessing space.

  1. National Security Implications of Inexpensive Space Access,

    DTIC Science & Technology

    2007-11-02

    to these techniques (such as eclipsing adversary solar panels or jamming uplinks), however, because rendezvous with, and capture of, hostile...are difficult to foresee and were already proposed as missions for the Space Shuttle in the early 1980s (and then turned out poorly). It may, in fact...these discussions in the late 1980s and early 1990s. At this point, political forces converged with SSTO technology. At the beginning of the Bush

  2. An overview of the EASE/ACCESS space construction demonstration

    NASA Technical Reports Server (NTRS)

    Levin, George M.; Ross, Jerry L.; Spring, Sherwood C.

    1988-01-01

    Consideration is given to the development of the Experimental Assembly of Structures in EVA/Assembly Concept for Construction of Erectable Space Structures (EASE/ACCESS) space construction demonstration, which was performed during Space Shuttle mission 61-B. The mission equipment is described and illustrated and the EASE/ACCESS mission management structure is outlined. Simulations of the assembly and disassembly in the NASA neutral buoyancy simulators were used to test the mission plans. In addition, EVA training and crew performance for the mission are discussed.

  3. Quantum effects and elimination of the conformal anomaly in anisotropic space-time

    SciTech Connect

    Grib, A.A.; Nesteruk, A.V.

    1988-03-01

    In homogeneous anisotropic space-time the connection between the problem of the elimination of infrared divergences and the conformal anomaly of the regularized energy-momentum tensor is studied. It is shown that removal of the infrared divergence by means of a cutoff leads to the absence of a conformal anomaly. A physical interpretation of the infrared cutoff as a shift in the particle-energy spectrum by an amount equal to the effective temperature of the gravitational field is proposed.

  4. 𝜖-expansion in critical ϕ3-theory on real projective space from conformal field theory

    NASA Astrophysics Data System (ADS)

    Hasegawa, Chika; Nakayama, Yu

    2017-03-01

    We use a compatibility between the conformal symmetry and the equations of motion to solve the one-point function in the critical ϕ3-theory (a.k.a. the critical Lee-Yang model) on the d = 6 ‑ 𝜖 dimensional real projective space to the first nontrivial order in the 𝜖-expansion. It reproduces the conventional perturbation theory and agrees with the numerical conformal bootstrap result.

  5. Density functional theory study of the conformational space of an infinitely long polypeptide chain

    NASA Astrophysics Data System (ADS)

    Ireta, Joel; Scheffler, Matthias

    2009-08-01

    The backbone conformational space of infinitely long polyalanine is investigated with density-functional theory and mapping the potential energy surface in terms of (L, θ) cylindrical coordinates. A comparison of the obtained (L, θ) Ramachandran-like plot with results from an extended set of protein structures shows excellent conformity, with the exception of the polyproline II region. It is demonstrated the usefulness of infinitely long polypeptide models for investigating the influence of hydrogen bonding and its cooperative effect on the backbone conformations. The results imply that hydrogen bonding together with long-range electrostatics is the main actuator for most of the structures assumed by protein residues.

  6. The National Aerospace Initiative (NAI): Technologies For Responsive Space Access

    NASA Technical Reports Server (NTRS)

    Culbertson, Andrew; Bhat, Biliyar N.

    2003-01-01

    The Secretary of Defense has set new goals for the Department of Defense (DOD) to transform our nation's military forces. The Director for Defense Research and Engineering (DDR&E) has responded to this challenge by defining and sponsoring a transformational initiative in Science and Technology (S&T) - the National Aerospace Initiative (NAI) - which will have a fundamental impact on our nation's military capabilities and on the aerospace industry in general. The NAI is planned as a joint effort among the tri-services, DOD agencies and National Aeronautics and Space Administration (NASA). It is comprised of three major focus areas or pillars: 1) High Speed Hypersonics (HSH), 2) Space Access (SA), and 3) Space Technology (ST). This paper addresses the Space Access pillar. The NAI-SA team has employed a unique approach to identifying critical technologies and demonstrations for satisfying both military and civilian space access capabilities needed in the future. For planning and implementation purposes the NAI-SA is divided into five technology subsystem areas: Airframe, Propulsion, Flight Subsystems, Operations and Payloads. Detailed technology roadmaps were developed under each subsystem area using a time-phased, goal oriented approach that provides critical space access capabilities in a timely manner and involves subsystem ground and flight demonstrations. This S&T plan addresses near-term (2009), mid-term (2016), and long-term (2025) goals and objectives for space access. In addition, system engineering and integration approach was used to make sure that the plan addresses the requirements of the end users. This paper describes in some detail the technologies in NAI-Space Access pillar. Some areas of emphasis are: high temperature materials, thermal protection systems, long life, lightweight, highly efficient airframes, metallic and composite cryotanks, advanced liquid rocket engines, integrated vehicle health monitoring and management, highly operable systems and

  7. Titan III - Commercial access to space

    NASA Astrophysics Data System (ADS)

    Gizinski, Stephen J., III; Herrington, Douglas B.

    1988-06-01

    The commercial Titan III launch vehicle is discussed, reviewing the history of the Titan program, the technical aspects of the launcher, and the market outlook. The solid rocket motors of the boost vehicle, core, attitude control system, and payload carrier are described. The vehicle can carry one or two payloads taking up a space of up to 3.65 m in diameter and 10.7 m in length. The avionics, communications, and electrical power systems of the vehicle are examined and the range of perigree stages with which the vehicle is compatible is given. An overview of the mission and the launch facilities is presented and future markets for commercial satellites are considered.

  8. Space construction results: The EASE/ACCESS flight experiment

    NASA Astrophysics Data System (ADS)

    Bekey, Ivan

    This paper describes NASA ground and flight test activities in the development of in-space construction techniques for the assembly of Space-Station-sized structures. In November 1985, the first experiments on space construction using EVA astronauts were flown aboard the Space Shuttle, with spectacular and highly visible results. The EASE and ACCESS flight experiments are described and the ground and water tank test program and operations in-flight including instrumentation are presented, together with illustrations of assembly and disassembly of both the EASE and ACCESS experiments. The flight test results are presented and learning and productivity curves are discussed, with differences between free EVA vs EVA using foot restraints compared. Two weeks after the flights, the Space Station structural assembly technique was selected to be EVA astronaut assembly of the truss, based on the flight experiment results.

  9. ClustENM: ENM-Based Sampling of Essential Conformational Space at Full Atomic Resolution

    PubMed Central

    Kurkcuoglu, Zeynep; Bahar, Ivet; Doruker, Pemra

    2016-01-01

    Accurate sampling of conformational space and, in particular, the transitions between functional substates has been a challenge in molecular dynamic (MD) simulations of large biomolecular systems. We developed an Elastic Network Model (ENM)-based computational method, ClustENM, for sampling large conformational changes of biomolecules with various sizes and oligomerization states. ClustENM is an iterative method that combines ENM with energy minimization and clustering steps. It is an unbiased technique, which requires only an initial structure as input, and no information about the target conformation. To test the performance of ClustENM, we applied it to six biomolecular systems: adenylate kinase (AK), calmodulin, p38 MAP kinase, HIV-1 reverse transcriptase (RT), triosephosphate isomerase (TIM), and the 70S ribosomal complex. The generated ensembles of conformers determined at atomic resolution show good agreement with experimental data (979 structures resolved by X-ray and/or NMR) and encompass the subspaces covered in independent MD simulations for TIM, p38, and RT. ClustENM emerges as a computationally efficient tool for characterizing the conformational space of large systems at atomic detail, in addition to generating a representative ensemble of conformers that can be advantageously used in simulating substrate/ligand-binding events. PMID:27494296

  10. GOES-R Space Weather Data: Ensuring Access and Usability

    NASA Astrophysics Data System (ADS)

    Tilton, M.; Rowland, W. F.; Wilkinson, D. C.; Denig, W. F.; Darnel, J.; Kress, B. T.; Loto'aniu, P. T. M.; Machol, J. L.; Redmon, R. J.; Rodriguez, J. V.

    2015-12-01

    The upcoming Geostationary Operational Environmental Satellite series, GOES-R, will provide critical space weather data. These data are used to prevent communication outages, mitigate the damage solar weather causes to satellites and power grids, and reduce astronaut radiation exposure. The space weather instruments aboard GOES-R will deliver an operational dataset of unprecedented breadth. However, NOAA's National Centers for Environmental Information (NCEI)—the organization that provides access to archived GOES-R data—has faced several challenges in delivering this information to customers in usable form. For instance, the GOES-R ground system was contracted to develop higher-level products for terrestrial data but not space weather data. Variations in GOES-R data file formats and archive locations have also threatened to create an inconsistent user experience. This presentation will examine the ways in which NCEI is making GOES-R space weather data more accessible and actionable for customers. These efforts include NCEI's development of high-level data products to meet the requirements of NOAA's Space Weather Prediction Center—a role NCEI has not previously played. In addition, NCEI is creating a demonstration system to show how these products can be produced in real-time. The organization is also examining customer usage of the GOES-NOP data access system and using these access patterns to drive decisions about the GOES-R user interface.

  11. Real-space visualization of conformation-independent oligothiophene electronic structure

    NASA Astrophysics Data System (ADS)

    Taber, Benjamen N.; Kislitsyn, Dmitry A.; Gervasi, Christian F.; Mills, Jon M.; Rosenfield, Ariel E.; Zhang, Lei; Mannsfeld, Stefan C. B.; Prell, James S.; Briseno, Alejandro L.; Nazin, George V.

    2016-05-01

    We present scanning tunneling microscopy and spectroscopy (STM/STS) investigations of the electronic structures of different alkyl-substituted oligothiophenes on the Au(111) surface. STM imaging showed that on Au(111), oligothiophenes adopted distinct straight and bent conformations. By combining STS maps with STM images, we visualize, in real space, particle-in-a-box-like oligothiophene molecular orbitals. We demonstrate that different planar conformers with significant geometrical distortions of oligothiophene backbones surprisingly exhibit very similar electronic structures, indicating a low degree of conformation-induced electronic disorder. The agreement of these results with gas-phase density functional theory calculations implies that the oligothiophene interaction with the Au(111) surface is generally insensitive to molecular conformation.

  12. Real-space visualization of conformation-independent oligothiophene electronic structure.

    PubMed

    Taber, Benjamen N; Kislitsyn, Dmitry A; Gervasi, Christian F; Mills, Jon M; Rosenfield, Ariel E; Zhang, Lei; Mannsfeld, Stefan C B; Prell, James S; Briseno, Alejandro L; Nazin, George V

    2016-05-21

    We present scanning tunneling microscopy and spectroscopy (STM/STS) investigations of the electronic structures of different alkyl-substituted oligothiophenes on the Au(111) surface. STM imaging showed that on Au(111), oligothiophenes adopted distinct straight and bent conformations. By combining STS maps with STM images, we visualize, in real space, particle-in-a-box-like oligothiophene molecular orbitals. We demonstrate that different planar conformers with significant geometrical distortions of oligothiophene backbones surprisingly exhibit very similar electronic structures, indicating a low degree of conformation-induced electronic disorder. The agreement of these results with gas-phase density functional theory calculations implies that the oligothiophene interaction with the Au(111) surface is generally insensitive to molecular conformation.

  13. Access from Space: A New Perspective on NASA's Space Transportation Technology Requirements and Opportunities

    NASA Technical Reports Server (NTRS)

    Rasky, Daniel J.

    2004-01-01

    The need for robust and reliable access from space is clearly demonstrated by the recent loss of the Space Shuttle Columbia; as well as the NASA s goals to get the Shuttle re-flying and extend its life, build new vehicles for space access, produce successful robotic landers and s a q k retrr? llisrions, and maximize the science content of ambitious outer planets missions that contain nuclear reactors which must be safe for re-entry after possible launch aborts. The technology lynch pin of access from space is hypersonic entry systems such the thermal protection system, along with navigation, guidance and control (NG&C). But it also extends to descent and landing systems such as parachutes, airbags and their control systems. Current space access technology maturation programs such as NASA s Next Generation Launch Technology (NGLT) program or the In-Space Propulsion (ISP) program focus on maturing laboratory demonstrated technologies for potential adoption by specific mission applications. A key requirement for these programs success is a suitable queue of innovative technologies and advanced concepts to mature, including mission concepts enabled by innovative, cross cutting technology advancements. When considering space access, propulsion often dominates the capability requirements, as well as the attention and resources. From the perspective of access from space some new cross cutting technology drivers come into view, along with some new capability opportunities. These include new miniature vehicles (micro, nano, and picosats), advanced automated systems (providing autonomous on-orbit inspection or landing site selection), and transformable aeroshells (to maximize capabilities and minimize weight). This paper provides an assessment of the technology drivers needed to meet future access from space mission requirements, along with the mission capabilities that can be envisioned from innovative, cross cutting access from space technology developments.

  14. Pilot Non-Conformance to Alerting System Commands During Closely Spaced Parallel Approaches

    NASA Technical Reports Server (NTRS)

    Pritchett, Amy Ruth; Hansman, R. John; Corker, Kevin (Technical Monitor)

    1997-01-01

    Cockpit alerting systems monitor potentially hazardous situations, both inside and outside the aircraft. When a hazard is projected to occur, the alerting system displays alerts and/or command decisions to the pilot. However, pilots have been observed to not conform to alerting system commands by delaying their response or by not following the automatic commands exactly. This non-conformance to the automatic alerting system can reduce its benefit. Therefore, a need exists to understand the causes and effects of pilot non-conformance in order to develop automatic alerting systems whose commands the pilots are more likely to follow. These considerations were examined through flight simulator evaluations of the collision avoidance task during closely spaced parallel approaches. This task provided a useful case-study because the effects of non-conformance can be significant, given the time-critical nature of the task. A preliminary evaluation of alerting systems identified non-conformance in over 40% of the cases and a corresponding drop in collision avoidance performance. A follow-on experiment found subjects' alerting and maneuver selection criteria were consistent with different strategies than those used by automatic systems, indicating the pilot may potentially disagree with the alerting system if the pilot attempts to verify automatic alerts and commanded avoidance maneuvers. A final experiment found supporting automatic alerts with the explicit display of its underlying criteria resulted in more consistent subject reactions. In light of these experimental results, a general discussion of pilot non-conformance is provided. Contributing factors in pilot non-conformance include a lack of confidence in the automatic system and mismatches between the alerting system's commands and the pilots' own decisions based on the information available to them. The effects of non-conformance on system performance are discussed. Possible methods of reconciling mismatches are

  15. Coset spaces and Einstein manifolds with l-conformal Galilei symmetry

    NASA Astrophysics Data System (ADS)

    Chernyavsky, Dmitry

    2016-10-01

    The group theoretic construction is applied to construct a novel dynamical realization of the l-conformal Galilei group in terms of geodesic equations on the coset space. A peculiar feature of the geodesics is that all their integrals of motion, including the accelerations, are functionally independent. The analysis in the recent work [Chernyavsky and Galajinsky (2016) [35

  16. Ka-band geostationary satellite spacing requirements and access schemes

    NASA Technical Reports Server (NTRS)

    Caron, Mario; Hindson, Daniel J.

    1995-01-01

    Geostationary satellite systems for wideband personal communications applications have been proposed. This paper looks at the geostationary satellite spacing requirement to meet the ITU-R sharing criterion for FDMA and CDMA access schemes. CDMA capacity equation is first developed. Then the basis for the interference analysis between two systems with an overlapping coverage area is developed for the cases of identical and different access schemes and for bandwidth and power limited systems. An example of an interference analysis between two systems is fully carried out. The paper also points out the inherent problems when comparing systems with different access schemes. It is found that under certain scenarios, CDMA can allow a closer spacing between satellites.

  17. Advanced Cosmic-Ray Composition Experiment for Space Station (ACCESS): ACCESS Accommodation Study Report

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L. (Editor); Wefel, John P. (Editor)

    1999-01-01

    In 1994 NASA Administrator selected the first high-energy particle physics experiment for the Space Station, the Alpha Magnetic Spectrometer (AMS), to place a magnetic spectrometer in Earth orbit and search for cosmic antimatter. A natural consequence of this decision was that NASA would begin to explore cost-effective ways through which the design and implementation of AMS might benefit other promising payload experiments. The first such experiment to come forward was Advanced Cosmic-Ray Composition Experiment for Space Station (ACCESS) in 1996. It was proposed as a new mission concept in space physics to attach a cosmic-ray experiment of weight, volume, and geometry similar to the AMS on the International Space Station (ISS), and replace the latter as its successor when the AMS is returned to Earth. This was to be an extension of NASA's suborbital balloon program, with balloon payloads serving as the precursor flights and heritage for ACCESS. The balloon programs have always been a cost-effective NASA resource since the particle physics instrumentation for balloon and space applications are directly related. The next step was to expand the process, pooling together expertise from various NASA centers and universities while opening up definition of the ACCESS science goals to the international community through the standard practice of peer review. This process is still ongoing, and the accommodation study presented here will discuss the baseline definition of ACCESS as we understand it today.

  18. Conformal prediction for anomaly detection and collision alert in space surveillance

    NASA Astrophysics Data System (ADS)

    Chen, Huimin; Chen, Genshe; Blasch, Erik; Pham, Khanh

    2013-05-01

    Anomaly detection has been considered as an important technique for detecting critical events in a wide range of data rich applications where a majority of the data is inconsequential and/or uninteresting. We study the detection of anomalous behaviors among space objects using the theory of conformal prediction for distribution-independent on-line learning to provide collision alerts with a desirable confidence level. We exploit the fact that conformal predictors provide valid forecasted sets at specified confidence levels under the relatively weak assumption that the normal training data, together with the normal testing data, are generated from the same distribution. If the actual observation is not included in the conformal prediction set, it is classified as anomalous at the corresponding significance level. Interpreting the significance level as an upper bound of the probability that a normal observation is mistakenly classified as anomalous, we can conveniently adjust the sensitivity to anomalies while controlling the false alarm rate without having to find the application specific threshold. The proposed conformal prediction method was evaluated for a space surveillance application using the open source North American Aerospace Defense Command (NORAD) catalog data. The validity of the prediction sets is justified by the empirical error rate that matches the significance level. In addition, experiments with simulated anomalous data indicate that anomaly detection sensitivity with conformal prediction is superior to that of the existing methods in declaring potential collision events.

  19. Distributions in Protein Conformation Space: Implications for Structure Prediction and Entropy

    PubMed Central

    Sullivan, David C.; Kuntz, Irwin D.

    2004-01-01

    By considering how polymer structures are distributed in conformation space, we show that it is possible to quantify the difficulty of structural prediction and to provide a measure of progress for prediction calculations. The critical issue is the probability that a conformation is found within a specified distance of another conformer. We address this question by constructing a cumulative distribution function (CDF) for the average probability from observations about its limiting behavior at small displacements and numerical simulations of polyalanine chains. We can use the CDF to estimate the likelihood that a structure prediction is better than random chance. For example, the chance of randomly predicting the native backbone structure of a 150-amino-acid protein to low resolution, say within 6 Å, is 10−14. A high-resolution structural prediction, say to 2 Å, is immensely more difficult (10−57). With additional assumptions, the CDF yields the conformational entropy of protein folding from native-state coordinate variance. Or, using values of the conformational entropy change on folding, we can estimate the native state's conformational span. For example, for a 150-mer protein, equilibrium α-carbon displacements in the native ensemble would be 0.3–0.5 Å based on TΔS of 1.42 kcal/(mol residue). PMID:15240450

  20. Integrated Ground Operations Demonstration for Responsive Space Access

    NASA Technical Reports Server (NTRS)

    Johnson, Robert G.; Notardonato, William U.

    2014-01-01

    The NASA Advanced Exploration Systems (AES) program has a three year project to develop and demonstrate technologies to fundamentally change the way ground servicing activities support future access to space architectures. The AES Integrated Ground Operation Demonstration Units (IGODU) project has created two test beds for investigating and maturing two key elements of spaceport processing activities. The first is the GODU Integrated Refrigeration and Storage test bed that is demonstrating zero-loss storage of liquid hydrogen propellants and studying the storage and transfer of densified propellants. The second activity is the GODU Autonomous Control test bed that is implementing health management technologies and autonomous control capability of the propellant loading process to reduce the standing army of experts historically needed to ensure safe propellant loading operations. This presentation will give an overview of the activities at the Kennedy Space Center on these two test beds and its potential impact on future access to space programs.

  1. Numerical solution of the wave equation on 1+1 Minkowski space-time with scri-fixing conformal compatification

    SciTech Connect

    Cruz-Osorio, A.; Lora-Clavijo, F. D.; Guzman, F. S.

    2010-07-12

    We solve numerically the wave equation on a fixed background space-time corresponding to 1+1 Minkowski space-time. In this case we use scri-fixing conformal compactifications and solve the wave equation on the conformal space-time. We draw space-time and conformal diagrams in order to describe the consistency of the results and the effects of the gauge choices. We are interested in containg g{sup +} in the numerical domain because such boundary is the future boundary of the wave function.

  2. Fluorine Substitution in Neurotransmitters: Microwave Spectroscopy and Modelling of the Conformational Space and Non Bonding Interactions

    NASA Astrophysics Data System (ADS)

    Melandri, S.; Maris, A.; Merloni, A.

    2011-06-01

    Fluorine substitution in molecules is a common practice in bio-organic chemistry in order to modulate physicochemical properties and biological activity of molecules and an increasing number of drugs on the market contain fluorine, the presence of which is often of major importance to modify pharmacokinetics properties and molecular activity. The rationale for such a strategy is that fluorine is generally a stronger electron acceptor than the other halogen atoms and its size is intermediate between that of hydrogen and oxygen. We have studied two fluorinated analogs of 2-phenylethylamine (PEA), the prototype molecule for adrenergic neurotransmitters, namely: 4-Fluoro (4FPEA) and 2-Fluoro-2-phenylethylamine (2FPEA) by Molecular Beam Fourier Transform Microwave Spectroscopy in the frequency range 6-18 GHz and ab initio calculations at the MP2/6311++G** level. The aim is to obtain information on the spatial arrangement of the ethylamine side chain and the effects of fluorination on the energy landscape. The conformational space is dominated by low energy gauche conformations stabilized by weak interactions between the aminic hydrogens and the electron cloud of the benzene ring and anti conformations higher in energy. In 2FPEA the presence of the fluorine atom almost duplicate the number of possible conformation with respect to 4FPEA. We observed two conformers of 4FPEA and five conformers of 2FPEA which have been classified with the guide provided by accurate ab initio calculations. The identification of the conformational species was helped by the analysis of the quadrupole hyperfine pattern which is greatly influenced by the orientation of the amino group and acts as a fingerprint for each conformation. The orientation of the dipole moment within the principal axis frame and the order of stability of the different conformations are other independent pieces of evidence for the unambiguous assignment and identification of the conformers. The order of stability was

  3. EASE/ACCESS ground processing at Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Moates, Deborah J.; Villamil, Ana M.

    1987-01-01

    The Kennedy Space Center (KSC) Payload Management and Operations Directorate is responsible for the processing of Space Shuttle payloads. The KSC responsibilities begin prior to hardware arrival at the launch site and extend until the experiments are returned to the investigators after the flight. The KSC involvement with the integration and checkout of payloads begins with participation in experiment, Mission Peculiar Equipment (MPE), and integrated payload design reviews. This involvement also includes participation in assembly and testing of flight hardware at the appropriate design center, university, or private corporation. Once the hardware arrives at the launch site, KSC personnel install the experiments and MPE onto a carrier in the Operations and Checkout (O & C) building. Following integration, the payload is functionally tested and then installed into the orbiter. After the mission, the payload is removed from the orbiter, deintegrated in the O & C building, and the experiments are turned over to the mission manager. One of the many payloads process at KSC consisted of two space construction experiments: the Experimental Assembly of Structures in Extravehicular Activity (EASE) and the Assembly Concept for Construction of Erectable Space Structures (ACCESS). The details of EASE/ACCESS integration, testing, and deintegration are addressed and how this mission can serve as a guide for future space construction payloads is discussed.

  4. Space construction results - The EASE/ACCESS flight experiment

    NASA Technical Reports Server (NTRS)

    Bekey, I.

    1986-01-01

    NASA ground and flight test activities aimed at the development of in-space construction techniques for the assembly of Space-Station-sized structures are described. In particular, attention is given to the EASE and ACCESS flight experiments, the ground and water tank program, and operations in-flight including instrumentations. The baseline experiments demonstrate that erectable structures can be assembled effectively by astronauts in EVA. The average assembly time for a 45-foot truss was 25.5 minutes; the assembly rate was 3.6 struts per minute.

  5. Exploration of the conformational space of a polymeric material that inhibits human immunodeficiency virus.

    PubMed

    Ercanli, Tulay; Boyd, Donald B

    2006-01-01

    Baertschi et al. (Antiviral Chem. Chemother. 1997, 8, 353-362) clarified the nature of a polymeric degradation product formed from the cephalosporin ceftazidime. Interest in the polymeric material arises from its ability to inhibit the RNase H and polymerase activities of HIV-1 reverse transcriptase (RT). To shed light on the structure of the polymeric material like that which forms from degradation of third-generation cephalosporins, we apply molecular modeling and other computational chemistry techniques. Aminothiazole methoxime (2-amino-4-thiazolyl-methoxyimino; ATMO) is the parent structure related to the isolated degradation product of ceftazidime. The MMFF94 force field and Monte Carlo multiple minimum method as implemented in MacroModel are used to generate low-energy conformers. We built up oligomeric models starting from the trimer to the 16-mer and performed distribution analyses on the dihedral angles from the Monte Carlo runs to analyze the three-dimensional shapes of the oligomers. Although the larger oligomers are too long for a complete search of conformational space, the low-energy conformers examined do not show secondary structure or repetitive conformations. Polymeric ATMO material may, therefore, exhibit only random coil conformations. Topological similarity of ATMO structures to other reported RT inhibitors is also examined.

  6. Conformational transition of giant DNA in a confined space surrounded by a phospholipid membrane.

    PubMed

    Kato, Ayako; Shindo, Eri; Sakaue, Takahiro; Tsuji, Akihiko; Yoshikawa, Kenichi

    2009-09-16

    It has been established that a long DNA molecule exhibits a large discrete conformational change from a coiled state to a highly folded state in aqueous solution, depending on the presence of various condensing agents such as polyamines. In this study, T4 DNA labeled with fluorescent dyes was encapsulated in a cell-sized microdroplet covered with a phospholipid membrane to investigate the conformational behavior of a DNA molecule in such a confined space. Fluorescence microscopy showed that the presence of Mg(2+) induced the adsorption of DNA onto the membrane inner-surface of a droplet composed of phosphatidylethanolamine, while no adsorption was observed onto a phosphatidylcholine membrane. Under the presence of spermine (tetravalent amine), DNA had a folded conformation in the bulk solution. However, when these molecules were encapsulated in the microdroplet, DNA adsorbed onto the membrane surface accompanied by unfolding of its structure into an extended coil conformation under high concentrations of Mg(2+). In addition, DNA molecules trapped in large droplets tended not to be adsorbed on the membrane, i.e., no conformational transition occurred. A thermodynamic analysis suggests that the translational entropy loss of a DNA molecule that is accompanied by adsorption is a key factor in these phenomena under micrometer-scale confinement.

  7. Conformational space annealing scheme in the inverse design of functional materials

    NASA Astrophysics Data System (ADS)

    Kim, Sunghyun; Lee, In-Ho; Lee, Jooyoung; Oh, Young Jun; Chang, Kee Joo

    2015-03-01

    Recently, the so-called inverse method has drawn much attention, in which specific electronic properties are initially assigned and target materials are subsequently searched. In this work, we develop a new scheme for the inverse design of functional materials, in which the conformational space annealing (CSA) algorithm for global optimization is combined with first-principles density functional calculations. To implement the CSA, we need a series of ingredients, (i) an objective function to minimize, (ii) a 'distance' measure between two conformations, (iii) a local enthalpy minimizer of a given conformation, (iv) ways to combine two parent conformations to generate a daughter one, (v) a special conformation update scheme, and (vi) an annealing method in the 'distance' parameter axis. We show the results of applications for searching for Si crystals with direct band gaps and the lowest-enthalpy phase of boron at a finite pressure and discuss the efficiency of the present scheme. This work is supported by the National Research Foundation of Korea (NRF) under Grant No. NRF-2005-0093845 and by Samsung Science and Technology Foundation under Grant No. SSTFBA1401-08.

  8. Advanced Cosmic Ray Composition Experiment for Space Station (ACCESS)

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.; Wefel, John P.

    1999-01-01

    In 1994 the first high-energy particle physics experiment for the Space Station, the Alpha Magnetic Spectrometer (AMS), was selected by NASA's Administrator as a joint collaboration with the U.S. Department of Energy (DOE). The AMS program was chartered to place a magnetic spectrometer in Earth orbit and search for cosmic antimatter. A natural consequence of this decision was that NASA would begin to explore cost-effective ways through which the design and implementation of AMS might benefit other promising payload experiments which were evolving from the Office of Space Science. The first such experiment to come forward was ACCESS in 1996. It was proposed as a new mission concept in space physics to place a cosmic-ray experiment of weight, volume, and geometry similar to the AMS on the ISS, and replace the latter as its successor when the AMS is returned to Earth. This was to be an extension of NASA's sub-orbital balloon program, with balloon payloads serving as the precursor flights and heritage for ACCESS. The balloon programs have always been a cost-effective NASA resource since the particle physics instrumentation for balloon and space applications are directly related. The next step was to expand the process, pooling together expertise from various NASA centers and universities while opening up definition of the ACCESS science goals to the international community through the standard practice of peer-review. This process is still on-going and the Accommodation Study presented here will discuss the baseline definition of ACCESS as we understand it today. Further detail on the history, scope, and background of the study is provided in Appendix A.

  9. MED-3DMC: a new tool to generate 3D conformation ensembles of small molecules with a Monte Carlo sampling of the conformational space.

    PubMed

    Sperandio, Olivier; Souaille, Marc; Delfaud, François; Miteva, Maria A; Villoutreix, Bruno O

    2009-04-01

    Obtaining an efficient sampling of the low to medium energy regions of a ligand conformational space is of primary importance for getting insight into relevant binding modes of drug candidates, or for the screening of rigid molecular entities on the basis of a predefined pharmacophore or for rigid body docking. Here, we report the development of a new computer tool that samples the conformational space by using the Metropolis Monte Carlo algorithm combined with the MMFF94 van der Waals energy term. The performances of the program have been assessed on 86 drug-like molecules that resulted from an ADME/tox profiling applied on cocrystalized small molecules and were compared with the program Omega on the same dataset. Our program has also been assessed on the 85 molecules of the Astex diverse set. Both test sets show convincing performance of our program at sampling the conformational space.

  10. Conformal Nets II: Conformal Blocks

    NASA Astrophysics Data System (ADS)

    Bartels, Arthur; Douglas, Christopher L.; Henriques, André

    2017-03-01

    Conformal nets provide a mathematical formalism for conformal field theory. Associated to a conformal net with finite index, we give a construction of the `bundle of conformal blocks', a representation of the mapping class groupoid of closed topological surfaces into the category of finite-dimensional projective Hilbert spaces. We also construct infinite-dimensional spaces of conformal blocks for topological surfaces with smooth boundary. We prove that the conformal blocks satisfy a factorization formula for gluing surfaces along circles, and an analogous formula for gluing surfaces along intervals. We use this interval factorization property to give a new proof of the modularity of the category of representations of a conformal net.

  11. Denatured proteins and early folding intermediates simulated in a reduced conformational space.

    PubMed

    Kmiecik, Sebastian; Kurcinski, Mateusz; Rutkowska, Aleksandra; Gront, Dominik; Kolinski, Andrzej

    2006-01-01

    Conformations of globular proteins in the denatured state were studied using a high-resolution lattice model of proteins and Monte Carlo dynamics. The model assumes a united-atom and high-coordination lattice representation of the polypeptide conformational space. The force field of the model mimics the short-range protein-like conformational stiffness, hydrophobic interactions of the side chains and the main-chain hydrogen bonds. Two types of approximations for the short-range interactions were compared: simple statistical potentials and knowledge-based protein-specific potentials derived from the sequence-structure compatibility of short fragments of protein chains. Model proteins in the denatured state are relatively compact, although the majority of the sampled conformations are globally different from the native fold. At the same time short protein fragments are mostly native-like. Thus, the denatured state of the model proteins has several features of the molten globule state observed experimentally. Statistical potentials induce native-like conformational propensities in the denatured state, especially for the fragments located in the core of folded proteins. Knowledge-based protein-specific potentials increase only slightly the level of similarity to the native conformations, in spite of their qualitatively higher specificity in the native structures. For a few cases, where fairly accurate experimental data exist, the simulation results are in semiquantitative agreement with the physical picture revealed by the experiments. This shows that the model studied in this work could be used efficiently in computational studies of protein dynamics in the denatured state, and consequently for studies of protein folding pathways, i.e. not only for the modeling of folded structures, as it was shown in previous studies. The results of the present studies also provide a new insight into the explanation of the Levinthal's paradox.

  12. Side-chain conformational space analysis (SCSA): a multi conformation-based QSAR approach for modeling and prediction of protein-peptide binding affinities.

    PubMed

    Zhou, Peng; Chen, Xiang; Shang, Zhicai

    2009-03-01

    In this article, the concept of multi conformation-based quantitative structure-activity relationship (MCB-QSAR) is proposed, and based upon that, we describe a new approach called the side-chain conformational space analysis (SCSA) to model and predict protein-peptide binding affinities. In SCSA, multi-conformations (rather than traditional single-conformation) have received much attention, and the statistical average information on multi-conformations of side chains is determined using self-consistent mean field theory based upon side chain rotamer library. Thereby, enthalpy contributions (including electrostatic, steric, hydrophobic interaction and hydrogen bond) and conformational entropy effects to the binding are investigated in terms of occurrence probability of residue rotamers. Then, SCSA was applied into the dataset of 419 HLA-A 0201 binding peptides, and nonbonding contributions of each position in peptide ligands are well determined. For the peptides, the hydrogen bond and electrostatic interactions of the two ends are essential to the binding specificity, van der Waals and hydrophobic interactions of all the positions ensure strong binding affinity, and the loss of conformational entropy at anchor positions partially counteracts other favorable nonbonding effects.

  13. Iterative derivation of effective potentials to sample the conformational space of proteins at atomistic scale

    NASA Astrophysics Data System (ADS)

    Capelli, Riccardo; Paissoni, Cristina; Sormanni, Pietro; Tiana, Guido

    2014-05-01

    The current capacity of computers makes it possible to perform simulations of small systems with portable, explicit-solvent potentials achieving high degree of accuracy. However, simplified models must be employed to exploit the behavior of large systems or to perform systematic scans of smaller systems. While powerful algorithms are available to facilitate the sampling of the conformational space, successful applications of such models are hindered by the availability of simple enough potentials able to satisfactorily reproduce known properties of the system. We develop an interatomic potential to account for a number of properties of proteins in a computationally economic way. The potential is defined within an all-atom, implicit solvent model by contact functions between the different atom types. The associated numerical values can be optimized by an iterative Monte Carlo scheme on any available experimental data, provided that they are expressible as thermal averages of some conformational properties. We test this model on three different proteins, for which we also perform a scan of all possible point mutations with explicit conformational sampling. The resulting models, optimized solely on a subset of native distances, not only reproduce the native conformations within a few Angstroms from the experimental ones, but show the cooperative transition between native and denatured state and correctly predict the measured free-energy changes associated with point mutations. Moreover, differently from other structure-based models, our method leaves a residual degree of frustration, which is known to be present in protein molecules.

  14. Conformational spaces of the gastrointestinal antisecretory chiral drug omeprazole: stereochemistry and tautomerism.

    PubMed

    Caner, Hava; Cheeseman, James R; Agranat, Israel

    2006-01-01

    A study of the conformational spaces of the chiral proton pump inhibitor (PPI) drug omeprazole by semiempirical, ab-initio, and DFT methods is described. In addition to the chiral center at the sulfinyl sulfur atom, the chiral axis at the pyridine ring (due to the hindered rotation of the 4-methoxy substituents) was considered. The results were analyzed in terms of the 5-methoxy and 6-methoxy tautomers and the two pairs of enantiomers (R,P)/(S,M) and (R,M)/(S,P). Five torsion angles were systematically explored: the backbone rotations defined by D1 (N3-C2-S10-O11), D2 (C2-S10-C12-C13), and D3 (S10-C12-C13-N14) and two methoxy rotations defined by D4 (C6-C5-O8-C9) and D5 (C16-C17-O19-C20). Significant energy differences were revealed between the 5- and 6-methoxy tautomers, the extended and folded conformations, and the (S,M) and (S,P) diastereomers. The "extended M" conformation of the 6-methoxy tautomer of (S)-omeprazole was found to be the most stable conformer.

  15. VIDARS: Towards Painless Access to Space Physics Data

    NASA Astrophysics Data System (ADS)

    Barry, B.; Vega, R.; Raeder, J.

    2006-12-01

    Space physics data sets are notoriously difficult to access, in particular if one wants to combine data sets from different sources. Part of the problem is finding the data. A myriad of different formats and containers poses another problem. Attempts to consolidate data in centers has not solved the problem. We present the prototype of a system (VIDARS, virtual data access and retrieval system) that addresses these issues. Data remain with their originators, but data sets are given unique names, called UDI (Universal Data Identifier), akin to Internet host names or e-mail addresses. The UDIs are known (registered) to one central server where they and associated meta data can be searched. Data access occurs completely transparent to a user such that for a requested UDI the central server returns the IP address of the data provider where the data can be retrieved using simple XML based protocols. This requires some cooperation from the data providers who need to register their data and implement the data server protocol, which is, however, very simple. The data access API allows for a wide variety of clients, ranging from simple ASCII dumps to sophisticated graphical and data mining applications, where the client never needs to know where the data actually reside.

  16. Permuting input for more effective sampling of 3D conformer space

    NASA Astrophysics Data System (ADS)

    Carta, Giorgio; Onnis, Valeria; Knox, Andrew J. S.; Fayne, Darren; Lloyd, David G.

    2006-03-01

    SMILES strings and other classic 2D structural formats offer a convenient way to represent molecules as a simplistic connection table, with the inherent advantages of ease of handling and storage. In the context of virtual screening, chemical databases to be screened are often initially represented by canonicalised SMILES strings that can be filtered and pre-processed in a number of ways, resulting in molecules that occupy similar regions of chemical space to active compounds of a therapeutic target. A wide variety of software exists to convert molecules into SMILES format, namely, Mol2smi (Daylight Inc.), MOE (Chemical Computing Group) and Babel (Openeye Scientific Software). Depending on the algorithm employed, the atoms of a SMILES string defining a molecule can be ordered differently. Upon conversion to 3D coordinates they result in the production of ostensibly the same molecule. In this work we show how different permutations of a SMILES string can affect conformer generation, affecting reliability and repeatability of the results. Furthermore, we propose a novel procedure for the generation of conformers, taking advantage of the permutation of the input strings—both SMILES and other 2D formats, leading to more effective sampling of conformation space in output, and also implementing fingerprint and principal component analyses step to post process and visualise the results.

  17. Aviation or space policy: New challenges for the insurance sector to private human access to space

    NASA Astrophysics Data System (ADS)

    van Oijhuizen Galhego Rosa, Ana Cristina

    2013-12-01

    The phenomenon of private human access to space has introduced a new set of problems in the insurance sector. Orbital and suborbital space transportation will surely be unique commercial services for this new market. Discussions are under way regarding space insurance, in order to establish whether this new market ought to be regulated by aviation or space law. Alongside new definitions, infrastructures, legal frameworks and liability insurances, the insurance sector has also been introducing a new approach. In this paper, I aim to analyse some of the possibilities of new premiums, capacities, and policies (under aviation or space insurance rules), as well as the new insurance products related to vehicles, passengers and third party liability. This paper claims that a change toward new insurance regimes is crucial, due to the current stage in development of space tourism and the urgency to adapt insurance rules to support future development in this area.

  18. Glycosylation of proteins: a computer based method for the rapid exploration of conformational space of N-glycans.

    PubMed

    Bohne, A; von der Lieth, C W

    2002-01-01

    Inspection of protein databases suggests that as many as 70% of proteins have potential N-glycosylation sites. Unfortunately glycoproteins often refuse to crystallize and NMR techniques do not allow an unambiguous determination of the complete conformation of the sugar part. Therefore, time-consuming complex simulation methods are often used to explore the conformational space of N-glycans. The generation of a comprehensive data base describing the conformational space of larger fragments of N-glycans taking into account the effects of branching is presented. High-temperature molecular dynamics simulations of essential N-glycan fragments are performed until conformational equilibrium has been reached. Free energy landscapes are calculated for each glycosidic linkage. All possible conformations for each N-glycan fragment are automatically assigned, ranked according to their relative population and stored in a database. These values are recalled for the generation of a complete set of all possible conformations for a given N-glycan topology. The constructed conformations are ranked according to their energy content. Since this approach allows to explore the complete conformational space of a given N-glycan within a few minutes of CPU-time on a standard PC, it is well suited to be used as a Web-Based application.

  19. Innovative Airbreathing Propulsion Concepts for Access to Space

    NASA Technical Reports Server (NTRS)

    Whitlow, Jr., Woodrow; Blech, Richard A.; Blankson, Isaiah M.

    2001-01-01

    This paper will present technologies and concepts for novel aeropropulsion systems. These technologies will enhance the safety of operations, reduce life cycle costs, and contribute to reduced costs of air travel and access to space. One of the goals of the NASA program is to reduce the carbon-dioxide emissions of aircraft engines. Engine concepts that use highly efficient fuel cell/electric drive technologies in hydrogen-fueled engines will be presented in the proposed paper. Carbon-dioxide emissions will be eliminated by replacing hydrocarbon fuel with hydrogen, and reduce NOx emissions through better combustion process control. A revolutionary exoskeletal engine concept, in which the engine drum is rotated, will be shown. This concept has the potential to allow a propulsion system that can be used for subsonic through hypersonic flight. Dual fan concepts that have ultra-high bypass ratios, low noise, and low drag will be presented. Flow-controlled turbofans and control-configured turbofans also will be discussed. To increase efficiency, a system of microengines distributed along lifting surfaces and on the fuselage is being investigated. This concept will be presented in the paper. Small propulsion systems for affordable, safe personal transportation vehicles will be discussed. These low-oil/oilless systems use technologies that enable significant cost and weight reductions. Pulse detonation engine-based hybrid-cycle and combined-cycle propulsion systems for aviation and space access will be presented.

  20. Sharing Ideas: Making Earth and Space Science Accessible

    NASA Astrophysics Data System (ADS)

    Runyon, C. J.; Guimond, K.; Atkinson, C.

    2005-12-01

    There are nearly six million K-12 students with some form of disability in the U.S. and the majority of them are required to achieve the same academic levels as their non-impaired peers. Historically, students with disabilities have experienced difficulties in fully accessing and participating in middle school and high school science programs. With the passage of the No Child Left Behind (NCLB) Act and increasing focus on reading and math performance, many students with exceptional needs are now being taught science by mainstream science teachers, who have little to no training on how to work with students with exceptional needs. For the past 5 years, SERCH has engaged in organizing and hosting a series of Exceptional Space Science Materials for Exceptional Students Workshops (ENWS) focused on educating students with special needs about the space sciences. Each workshop has focused on a different aspect of formal and informal education and working with the various special needs. In all of these workshops, participants experience what a person or student with special needs might encounter when working through educational activities or exhibits by experiencing it first-hand. In addition to making many of NASA's education materials accessible for all learners, a top-ten list of "best practices" has been compiled by the professional educators as a result of our working together for five years and their formal and informal educational experiences.

  1. Why Atens Enjoy Enhanced Accessibility For Human Space Flight

    NASA Technical Reports Server (NTRS)

    Barbee, Brent; Adamo, Daniel

    2011-01-01

    In the context of human space flight (HSF), the concept of near-Earth object (NEO) accessibility is highly subjective. Whether or not a particular NEO is accessible critically depends on mass, performance, and reliability of interplanetary HSF systems yet to be designed. Such systems would certainly include propulsion and crew life support with adequate shielding from both solar flares and galactic cosmic radiation. Equally critical architecture options are relevant to NEO accessibility. These options are also far from being determined and include the number of launches supporting an HSF mission, together with whether or not consumables are to be pre-emplaced at the destination. Until the unknowns of HSF to NEOs come into clearer focus, the notion of relative accessibility is of great utility. Imagine a group of NEOs, each with nearly equal HSF merit determined from their individual characteristics relating to crew safety, scientific return, resource utilization, and planetary defense. The more accessible members of this group are more likely to be explored first. A highly accessible NEO could conceivably be deferred in favor of a less accessible HSF destination because the latter is more accessible during a programmatically desirable launch compliant mission trajectory solutions detected in association with a specific NEO. The known NEO population is then surveyed to illustrate in which regions of heliocentric semi-major axis, eccentricity, and inclination (a, e, i) space NEOs with large n values are mapped. The (a, e, i) mapping is also formatted such that membership in each of four NEO orbit classifications, as defined below, is evident. Amors have orbits everywhere superior to (outside of) Earth's. An Amor is therefore defined to have perihelion between 1.017 astronomical units (AU) and the maximum NEO value of 1.3 AU. As of 0 hrs Universal Time on 1 January 2011 (UT epoch 2011.0), Amors numbered 2855 in the Jet Propulsion Laboratory (JPL) Small-Body Database

  2. Enabling Dedicated, Affordable Space Access Through Aggressive Technology Maturation

    NASA Technical Reports Server (NTRS)

    Jones, Jonathan; Kibbey, Tim; Lampton, Pat; Brown, Thomas

    2014-01-01

    A recent explosion in nano-sat, small-sat, and university class payloads has been driven by low cost electronics and sensors, wide component availability, as well as low cost, miniature computational capability and open source code. Increasing numbers of these very small spacecraft are being launched as secondary payloads, dramatically decreasing costs, and allowing greater access to operations and experimentation using actual space flight systems. While manifesting as a secondary payload provides inexpensive rides to orbit, these arrangements also have certain limitations. Small, secondary payloads are typically included with very limited payload accommodations, supported on a non interference basis (to the prime payload), and are delivered to orbital conditions driven by the primary launch customer. Integration of propulsion systems or other hazardous capabilities will further complicate secondary launch arrangements, and accommodation requirements. The National Aeronautics and Space Administration's Marshall Space Flight Center has begun work on the development of small, low cost launch system concepts that could provide dedicated, affordable launch alternatives to small, risk tolerant university type payloads and spacecraft. These efforts include development of small propulsion systems and highly optimized structural efficiency, utilizing modern advanced manufacturing techniques. This paper outlines the plans and accomplishments of these efforts and investigates opportunities for truly revolutionary reductions in launch and operations costs. Both evolution of existing sounding rocket systems to orbital delivery, and the development of clean sheet, optimized small launch systems are addressed. A launch vehicle at the scale and price point which allows developers to take reasonable risks with new propulsion and avionics hardware solutions does not exist today. Establishing this service provides a ride through the proverbial "valley of death" that lies between

  3. The Hubble law as a kinematic outcome of the space-time conformal geometry

    SciTech Connect

    Tomilchik, L. M.

    2010-03-24

    The description of the cosmological expansion and its possible local manifestations as a pure kinematic effects of the space-time conformal geometry is given. The explicit form of the conformal deformation of time is established. The expression de pound ning the cosmological distance in the form of simple function on the red shift is obtained. By coupling it with the relativistic formula for the longitudinal Doppler effect, the explicit analytic expression for the Hubble law is obtained. The expression generalizing the standard Hubble law reproduces the experimentally observed phenomenon treated conventionally as a Dark Energy manifestation. The expression for conformal time deformation in the small time limit leads to the quadratic time nonlinearity. Being applied to describe the location-type experiments, this predicts the existence of the universal uniformly changing blue-shifted frequency drift. Phenomenon of the Pioneer Anomaly (PA) is treated as the pound rst of such a kind of effects discovered experimentally. The obtained formulae reproduce the Pioneer Anomaly experimental data.

  4. Efficient solid rocket propulsion for access to space

    NASA Astrophysics Data System (ADS)

    Maggi, Filippo; Bandera, Alessio; Galfetti, Luciano; De Luca, Luigi T.; Jackson, Thomas L.

    2010-06-01

    Space launch activity is expected to grow in the next few years in order to follow the current trend of space exploitation for business purpose. Granting high specific thrust and volumetric specific impulse, and counting on decades of intense development, solid rocket propulsion is a good candidate for commercial access to space, even with common propellant formulations. Yet, some drawbacks such as low theoretical specific impulse, losses as well as safety issues, suggest more efficient propulsion systems, digging into the enhancement of consolidated techniques. Focusing the attention on delivered specific impulse, a consistent fraction of losses can be ascribed to the multiphase medium inside the nozzle which, in turn, is related to agglomeration; a reduction of agglomerate size is likely. The present paper proposes a model based on heterogeneity characterization capable of describing the agglomeration trend for a standard aluminized solid propellant formulation. Material microstructure is characterized through the use of two statistical descriptors (pair correlation function and near-contact particles) looking at the mean metal pocket size inside the bulk. Given the real formulation and density of a propellant, a packing code generates the material representative which is then statistically analyzed. Agglomerate predictions are successfully contrasted to experimental data at 5 bar for four different formulations.

  5. TPS Sizing for Access-to-Space Vehicles

    NASA Technical Reports Server (NTRS)

    Henline, William; Olynick, David; Palmer, Grant; Chen, Y.-K.

    1996-01-01

    A study was carried out to identify, develop, and benchmark simulation techniques needed for optimum thermal protection system (TPS) material selection and sizing for reusable launch vehicles. Fully viscous, chemically reacting, Navier-Stokes flow solutions over the Langley wing-body single stage to orbit (SSTO) configuration were generated and coupled with an in-depth conduction code. Results from the study provide detailed TPS heat shield materials selection and thickness sizing for the wing-body SSTO. These results are the first ever achieved through the use of a complete, trajectory based hypersonic, Navier-Stokes solution database. TPS designs were obtained for both laminar and turbulent entry trajectories using the Access-to-Space baseline materials such as tailorable advanced blanket insulation. The TPS design effects (materials selection and thickness) of coupling material characteristics to the aerothermal environment are illustrated. Finally, a sample validation case using the shuttle flight database is included.

  6. An Account of Advances in Accessing ``Discovery Space''

    NASA Astrophysics Data System (ADS)

    Harwit, Martin

    2017-01-01

    Our knowledge of the origin, early history, and evolution of the Universe, though necessarily based on physical and chemical processes confirmed in the laboratory, inevitably requires verification through direct astronomical observation. The range of potential observations, however, is limited by inherent cosmic features: For electromagnetic radiation, e.g., through erasure of information during early epochs when the cosmic plasma was opaque; for cosmic rays through the Greisen-Zatsepin-Kuz'min cut-off. I will take stock of the progress astronomers have made in accessing ``discovery space'' - the range of observations permitted despite such inherent cosmic limits - to provide an account of the rates at which realizable observations have accumulated over recent decades, while also highlighting work remaining to be done and areas in which progress has been thwarted.

  7. New binding site conformations of the dengue virus NS3 protease accessed by molecular dynamics simulation.

    PubMed

    de Almeida, Hugo; Bastos, Izabela M D; Ribeiro, Bergmann M; Maigret, Bernard; Santana, Jaime M

    2013-01-01

    Dengue fever is caused by four distinct serotypes of the dengue virus (DENV1-4), and is estimated to affect over 500 million people every year. Presently, there are no vaccines or antiviral treatments for this disease. Among the possible targets to fight dengue fever is the viral NS3 protease (NS3PRO), which is in part responsible for viral processing and replication. It is now widely recognized that virtual screening campaigns should consider the flexibility of target protein by using multiple active conformational states. The flexibility of the DENV NS3PRO could explain the relatively low success of previous virtual screening studies. In this first work, we explore the DENV NS3PRO conformational states obtained from molecular dynamics (MD) simulations to take into account protease flexibility during the virtual screening/docking process. To do so, we built a full NS3PRO model by multiple template homology modeling. The model comprised the NS2B cofactor (essential to the NS3PRO activation), a glycine flexible link and the proteolytic domain. MD simulations had the purpose to sample, as closely as possible, the ligand binding site conformational landscape prior to inhibitor binding. The obtained conformational MD sample was clustered into four families that, together with principal component analysis of the trajectory, demonstrated protein flexibility. These results allowed the description of multiple binding modes for the Bz-Nle-Lys-Arg-Arg-H inhibitor, as verified by binding plots and pair interaction analysis. This study allowed us to tackle protein flexibility in our virtual screening campaign against the dengue virus NS3 protease.

  8. Space Access for Small Satellites on the K-1

    NASA Astrophysics Data System (ADS)

    Faktor, L.

    Affordable access to space remains a major obstacle to realizing the increasing potential of small satellites systems. On a per kilogram basis, small launch vehicles are simply too expensive for the budgets of many small satellite programs. Opportunities for rideshare with larger payloads on larger launch vehicles are still rare, given the complications associated with coordinating delivery schedules and deployment orbits. Existing contractual mechanisms are also often inadequate to facilitate the launch of multiple payload customers on the same flight. Kistler Aerospace Corporation is committed to lowering the price and enhancing the availability of space access for small satellite programs through the fully-reusable K-1 launch vehicle. Kistler has been working with a number of entities, including Astrium Ltd., AeroAstro, and NASA, to develop innovative approaches to small satellite missions. The K-1 has been selected by NASA as a Flight Demonstration Vehicle for the Space Launch Initiative. NASA has purchased the flight results during the first four K-1 launches on the performance of 13 advanced launch vehicle technologies embedded in the K-1 vehicle. On K-1 flights #2-#4, opportunities exist for small satellites to rideshare to low-earth orbit for a low-launch price. Kistler's flight demonstration contract with NASA also includes options to fly Add-on Technology Experiment flights. Opportunities exist for rideshare payloads on these flights as well. Both commercial and government customers may take advantage of the rideshare pricing. Kistler is investigating the feasibility of flying dedicated, multiple small payload missions. Such a mission would launch multiple small payloads from a single customer or small payloads from different customers. The orbit would be selected to be compatible with the requirements of as many small payload customers as possible, and make use of reusable hardware, standard interfaces (such as the existing MPAS) and verification plans

  9. Developing hybrid near-space technologies for affordable access to suborbital space

    NASA Astrophysics Data System (ADS)

    Badders, Brian David

    High power rockets and high altitude balloons are two near-space technologies that could be combined in order to provide access to the mesosphere and, eventually, suborbital space. This "rockoon" technology has been used by several large budget space programs before being abandoned in favor of even more expensive, albeit more accurate, ground launch systems. With the increased development of nano-satellites and atmospheric sensors, combined with rising interest in global atmospheric data, there is an increase in desire for affordable access to extreme altitudes that does not necessarily require the precision of ground launches. Development of hybrid near-space technologies for access to over 200k ft. on a small budget brings many challenges within engineering, systems integration, cost analysis, market analysis, and business planning. This research includes the design and simulation testing of all the systems needed for a safe and reusable launch system, the cost analysis for initial production, the development of a business plan, and the development of a marketing plan. This project has both engineering and scientific significance in that it can prove the space readiness of new technologies, raise their technology readiness levels (TRLs), expedite the development process, and also provide new data to the scientific community. It also has the ability to stimulate university involvement in the aerospace industry and help to inspire the next generation of workers in the space sector. Previous development of high altitude balloon/high power rocket hybrid systems have been undertaken by government funded military programs or large aerospace corporations with varying degrees of success. However, there has yet to be a successful flight with this type of system which provides access to the upper mesosphere in a university setting. This project will aim to design and analyze a viable system while testing the engineering process under challenging budgetary constraints. The

  10. LigDockCSA: protein-ligand docking using conformational space annealing.

    PubMed

    Shin, Woong-Hee; Heo, Lim; Lee, Juyong; Ko, Junsu; Seok, Chaok; Lee, Jooyoung

    2011-11-30

    Protein-ligand docking techniques are one of the essential tools for structure-based drug design. Two major components of a successful docking program are an efficient search method and an accurate scoring function. In this work, a new docking method called LigDockCSA is developed by using a powerful global optimization technique, conformational space annealing (CSA), and a scoring function that combines the AutoDock energy and the piecewise linear potential (PLP) torsion energy. It is shown that the CSA search method can find lower energy binding poses than the Lamarckian genetic algorithm of AutoDock. However, lower-energy solutions CSA produced with the AutoDock energy were often less native-like. The loophole in the AutoDock energy was fixed by adding a torsional energy term, and the CSA search on the refined energy function is shown to improve the docking performance. The performance of LigDockCSA was tested on the Astex diverse set which consists of 85 protein-ligand complexes. LigDockCSA finds the best scoring poses within 2 Å root-mean-square deviation (RMSD) from the native structures for 84.7% of the test cases, compared to 81.7% for AutoDock and 80.5% for GOLD. The results improve further to 89.4% by incorporating the conformational entropy.

  11. TRACER. A new approach to comparative modeling that combines threading with free-space conformational sampling.

    PubMed

    Trojanowski, Sebastian; Rutkowska, Aleksandra; Kolinski, Andrzej

    2010-01-01

    A new approach to comparative modeling of proteins, TRACER, is described and benchmarked against classical modeling procedures. The new method unifies true three-dimensional threading with coarse-grained sampling of query protein conformational space. The initial sequence alignment of a query protein with a template is not required, although a template needs to be somehow identified. The template is used as a multi-featured fuzzy three-dimensional scaffold. The conformational search for the query protein is guided by intrinsic force field of the coarse-grained modeling engine CABS and by compatibility with the template scaffold. During Replica Exchange Monte Carlo simulations the model chain representing the query protein finds the best possible structural alignment with the template chain, that also optimizes the intra-protein interactions as approximated by the knowledge based force field of CABS. The benchmark done for a representative set of query/template pairs of various degrees of sequence similarity showed that the new method allows meaningful comparative modeling also for the region of marginal, or non-existing, sequence similarity. Thus, the new approach significantly extends the applicability of comparative modeling.

  12. New Specimen Access Device for the Large Space Simulator

    NASA Astrophysics Data System (ADS)

    Lazzarini, P.; Ratti, F.

    2004-08-01

    The Large Space Simulator (LSS) is used to simulate in- orbit environmental conditions for spacecraft (S/C) testing. The LSS is intended to be a flexible facility: it can accommodate test articles that can differ significantly in shape and weight and carry various instruments. To improve the accessibility to the S/C inside the LSS chamber a new Specimen Access Device (SAD) has been procured. The SAD provides immediate and easy access to the S/C, thus reducing the amount of time necessary for the installations of set-ups in the LSS. The SAD has been designed as bridge crane carrying a basket to move the operator into the LSS. Such a crane moves on parallel rails on the top floor of the LSS building. The SAD is composed by three subsystems: the main bridge, the trolley that moves along the main bridge and the telescopic mast. A trade off analysis has been carried out for what concerns the telescopic mast design. The choice between friction pads vs rollers, to couple the different sections of the mast, has been evaluated. The resulting design makes use of a four sections square mast, with rollers driven deployment. This design has been chosen for the higher stiffness of the mast, due to the limited number of sections, and because it reduces radically the risk of contamination related to a solution based on sliding bushings. Analyses have been performed to assess the mechanical behaviour both in static and in dynamic conditions. In particular the telescopic mast has been studied in detail to optimise its stiffness and to check the safety margins in the various operational conditions. To increase the safety of the operations an anticollision system has been implemented by positioning on the basket two kind of sensors, ultrasonic and contact ones. All the translations are regulated by inverters with acceleration and deceleration ramps controlled by a Programmable Logic Controller (PLC). An absolute encoder is installed on each motor to provide the actual position of the

  13. Modeling the accessible conformations of the intrinsically unstructured transactivation domain of p53.

    PubMed

    Lowry, David F; Stancik, Amber; Shrestha, Ranjay Mann; Daughdrill, Gary W

    2008-05-01

    Internuclear distances derived from paramagnetic relaxation enhancement (PRE) data were used to restrain molecular dynamics simulations of the intrinsically unstructured transactivation domain of the tumor suppressor protein, p53. About 1000 structures were simulated using ensemble averaging of replicate molecules to compensate for the inherent bias in the PRE-derived distances. Gyration radii measurements on these structures show that the p53 transactivation domain (p53TAD) is statistically predominantly in a partially collapsed state that is unlike the open structure that is found for p53TAD bound to either the E3 ubiquitin ligase, MDM2, or the 70 kDa subunit of replication protein A, RPA70. Contact regions that potentially mediate the collapse were identified and found to consist of mostly hydrophobic residues. The identified contact regions preferentially place the MDM2 and RPA70 binding regions in close proximity. We show that our simulations thoroughly sample the available range of conformations and that a fraction of the molecules are in an open state that would be competent for binding either MDM2 or RPA70. We also show that the Stokes radius estimated from the average gyration radius of the ensemble is in good agreement with the value determined using size exclusion chromatography. Finally, the presence of a persistent loop localized to a PXP motif was identified. Serine residues flanking the PXP motif become phosphorylated in response to DNA damage, and we postulate that this will perturb the equilibrium population to more open conformations.

  14. Truncated conformal space approach for 2D Landau–Ginzburg theories

    DOE PAGES

    Coser, A.; Beria, M.; Brandino, G. P.; ...

    2014-12-10

    In this study, We examine the spectrum of Landau–Ginzburg theories in 1 + 1 dimensions using the truncated conformal space approach employing a compactified boson. We study these theories both in their broken and unbroken phases. We first demonstrate that we can reproduce the expected spectrum of a Φ² theory (i.e. a free massive boson) in this framework. We then turn to Φ⁴ in its unbroken phase and compare our numerical results with the predictions of two-loop perturbation theory, finding excellent agreement. We then analyze the broken phase of Φ⁴ where kink excitations together with their bound states are present.more » We confirm the semiclassical predictions for this model on the number of stable kink-antikink bound states. We also test the semiclassics in the double well phase of Φ⁶ Landau-Ginzburg theory, again finding agreement.« less

  15. Truncated conformal space approach for 2D Landau–Ginzburg theories

    SciTech Connect

    Coser, A.; Beria, M.; Brandino, G. P.; Konik, R. M.; Mussardo, G.

    2014-12-10

    In this study, We examine the spectrum of Landau–Ginzburg theories in 1 + 1 dimensions using the truncated conformal space approach employing a compactified boson. We study these theories both in their broken and unbroken phases. We first demonstrate that we can reproduce the expected spectrum of a Φ² theory (i.e. a free massive boson) in this framework. We then turn to Φ⁴ in its unbroken phase and compare our numerical results with the predictions of two-loop perturbation theory, finding excellent agreement. We then analyze the broken phase of Φ⁴ where kink excitations together with their bound states are present. We confirm the semiclassical predictions for this model on the number of stable kink-antikink bound states. We also test the semiclassics in the double well phase of Φ⁶ Landau-Ginzburg theory, again finding agreement.

  16. A field-space conformal-solution method: Binary vapor-liquid phase behavior

    NASA Astrophysics Data System (ADS)

    Storvick, T. S.; Fox, J. R.

    1990-01-01

    The field-space conformal solution method provides an entirely new thermodynamic framework for the description of fluid mixtures in terms of the properties of a pure reference fluid. The utility and performance of the method are examined in the special case of vapor-liquid equilibrium correlation for simple mixtures. This is one of several cases in which field-space methods have numerical or theoretical advantages over methods presently used in mixture property correlation; only properties along the vapor pressure curve of the purefluid reference system are required for a complete description of the mixture phase behavior. Vapor-liquid equilibrium data for three binary hydrocarbon mixtures, n-butane + n-pentane, n-butane + n-hexane, and n-butane + n-octane, are correlated with a simple implementation of the method having two independent mixture parameters. Two pure-fluid equations of state, a Peng-Robinson equation and a 32-constant modified Benedict-Webb-Rubin equation, are tested as reference systems. The effects of differences in the quality of the reference system and of a range of mixture component size ratios are examined.

  17. Marshall Space Flight Center's role in EASE/ACCESS mission management

    NASA Technical Reports Server (NTRS)

    Hawkins, Gerald W.

    1987-01-01

    The Marshall Space Flight Center (MSFC) Spacelab Payload Project Office was responsible for the mission management and development of several successful payloads. Two recent space construction experiments, the Experimental Assembly of Structures in Extravehicular Activity (EASE) and the Assembly Concept for Construction of Erectable Space Structures (ACCESS), were combined into a payload managed by the center. The Ease/ACCESS was flown aboard the Space Shuttle Mission 61-B. The EASE/ACCESS experiments were the first structures assembled in space, and the method used to manage this successful effort will be useful for future space construction missions. The MSFC mission management responsibilities for the EASE/ACCESS mission are addressed and how the lessons learned from the mission can be applied to future space construction projects are discussed.

  18. A Novel Method Using Abstract Convex Underestimation in Ab-Initio Protein Structure Prediction for Guiding Search in Conformational Feature Space.

    PubMed

    Hao, Xiao-Hu; Zhang, Gui-Jun; Zhou, Xiao-Gen; Yu, Xu-Feng

    2016-01-01

    To address the searching problem of protein conformational space in ab-initio protein structure prediction, a novel method using abstract convex underestimation (ACUE) based on the framework of evolutionary algorithm was proposed. Computing such conformations, essential to associate structural and functional information with gene sequences, is challenging due to the high-dimensionality and rugged energy surface of the protein conformational space. As a consequence, the dimension of protein conformational space should be reduced to a proper level. In this paper, the high-dimensionality original conformational space was converted into feature space whose dimension is considerably reduced by feature extraction technique. And, the underestimate space could be constructed according to abstract convex theory. Thus, the entropy effect caused by searching in the high-dimensionality conformational space could be avoided through such conversion. The tight lower bound estimate information was obtained to guide the searching direction, and the invalid searching area in which the global optimal solution is not located could be eliminated in advance. Moreover, instead of expensively calculating the energy of conformations in the original conformational space, the estimate value is employed to judge if the conformation is worth exploring to reduce the evaluation time, thereby making computational cost lower and the searching process more efficient. Additionally, fragment assembly and the Monte Carlo method are combined to generate a series of metastable conformations by sampling in the conformational space. The proposed method provides a novel technique to solve the searching problem of protein conformational space. Twenty small-to-medium structurally diverse proteins were tested, and the proposed ACUE method was compared with It Fix, HEA, Rosetta and the developed method LEDE without underestimate information. Test results show that the ACUE method can more rapidly and more

  19. Second order superintegrable systems in conformally flat spaces. IV. The classical 3D Staeckel transform and 3D classification theory

    SciTech Connect

    Kalnins, E.G.; Kress, J.M.; Miller, W. Jr.

    2006-04-15

    This article is one of a series that lays the groundwork for a structure and classification theory of second order superintegrable systems, both classical and quantum, in conformally flat spaces. In the first part of the article we study the Staeckel transform (or coupling constant metamorphosis) as an invertible mapping between classical superintegrable systems on different three-dimensional spaces. We show first that all superintegrable systems with nondegenerate potentials are multiseparable and then that each such system on any conformally flat space is Staeckel equivalent to a system on a constant curvature space. In the second part of the article we classify all the superintegrable systems that admit separation in generic coordinates. We find that there are eight families of these systems.

  20. Evolution of area access safety training required for gaining access to Space Shuttle launch and landing facilities

    NASA Technical Reports Server (NTRS)

    Willams, M. C.

    1985-01-01

    Assuring personnel and equipment are fully protected during the Space Shuttle launch and landing operations has been a primary concern of NASA and its associated contractors since the inception of the program. A key factor in support of this policy has been the area access safety training requirements for badging of employees assigned to work on Space Shuttle Launch and Facilities. This requirement was targeted for possible cost savings and the transition of physical on-site walkdowns to the use of television tapes has realized program cost savings while continuing to fully satisfy the area access safety training requirements.

  1. A conformal boundary for space-times based on light-like geodesics: The 3-dimensional case

    NASA Astrophysics Data System (ADS)

    Bautista, A.; Ibort, A.; Lafuente, J.; Low, R.

    2017-02-01

    A new causal boundary, which we will term the l-boundary, inspired by the geometry of the space of light rays and invariant by conformal diffeomorphisms for space-times of any dimension m ≥3 , proposed by one of the authors [R. J. Low, The Space of Null Geodesics (and a New Causal Boundary), Lecture Notes in Physics 692 (Springer, 2006), pp. 35-50] is analyzed in detail for space-times of dimension 3. Under some natural assumptions, it is shown that the completed space-time becomes a smooth manifold with boundary and its relation with Geroch-Kronheimer-Penrose causal boundary is discussed. A number of examples illustrating the properties of this new causal boundary as well as a discussion on the obtained results will be provided.

  2. A note on conformally compactified connection dynamics tailored for anti-de Sitter space

    NASA Astrophysics Data System (ADS)

    Bodendorfer, N.

    2016-12-01

    A framework conceptually based on the conformal techniques employed to study the structure of the gravitational field at infinity is set up in the context of loop quantum gravity to describe asymptotically anti-de Sitter quantum spacetimes. A conformal compactification of the spatial slice is performed, which, in terms of the rescaled metric, has now finite volume, and can thus be conveniently described by spin networks states. The conformal factor used is a physical scalar field, which has the necessary asymptotics for many asymptotically AdS black hole solutions.

  3. Attached shuttle payload carriers: Versatile and affordable access to space

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The shuttle has been primarily designed to be a versatile vehicle for placing a variety of scientific and technological equipment in space including very large payloads; however, since many large payloads do not fill the shuttle bay, the space and weight margins remaining after the major payloads are accommodated often can be made available to small payloads. The Goddard Space Flight Center (GSFC) has designed standardized mounting structures and other support systems, collectively called attached shuttle payload (ASP) carriers, to make this additional space available to researchers at a relatively modest cost. Other carrier systems for ASP's are operated by other NASA centers. A major feature of the ASP carriers is their ease of use in the world of the Space Shuttle. ASP carriers attempt to minimized the payload interaction with Space Transportation System (STS) operations whenever possible. Where this is not possible, the STS services used are not extensive. As a result, the interfaces between the carriers and the STS are simplified. With this near autonomy, the requirements for supporting documentation are considerably lessened and payload costs correspondingly reduced. The ASP carrier systems and their capabilities are discussed in detail. The range of available capabilities assures that an experimenter can select the simplest, most cost-effective carrier that is compatible with his or her experimental objectives. Examples of payloads which use ASP basic hardware in nonstandard ways are also described.

  4. Analyzing green/open space accessibility by using GIS: case study of northern Cyprus cities

    NASA Astrophysics Data System (ADS)

    Kara, Can; Akçit, Nuhcan

    2015-06-01

    It is well known that green spaces are vital for increasing the quality of life within the urban environment. World Health Organization states that it should be 9 square meters per person at least. European Environment Agency defines that 5000 square meters of green space should be accessible within 300 meters distance from households. Green structure in Northern Cyprus is not sufficient and effective in this manner. In Northern Cyprus, they have neglected the urban planning process and they have started to lose significance and importance. The present work analyzes the accessibility of green spaces in Northern Cyprus cities. Kioneli, Famagusta, Kyrenia and the northern part of Nicosia are analyzed in this manner. To do that, green space structure is analyzed by using digital data. Additionally, accessibility of the green space is measured by using 300-meter buffers for each city. Euclidean distance is used from each building and accessibility maps are generated. Kyrenia and Famagusta have shortage in green space per capita. The amount of green space in these cities is less than 4 square meters. The factors affecting the accessibility and utilization of public spaces are discussed to present better solutions to urban planning.

  5. Secure Payload Access to the International Space Station

    NASA Technical Reports Server (NTRS)

    Pitts, R. Lee; Reid, Chris

    2002-01-01

    The ISS finally reached an operational state and exists for local and remote users. Onboard payload systems are managed by the Huntsville Operations Support Center (HOSC). Users access HOSC systems by internet protocols in support of daily operations, preflight simulation, and test. In support of this diverse user community, a modem security architecture has been implemented. The architecture has evolved over time from an isolated but open system to a system which supports local and remote access to the ISS over broad geographic regions. This has been accomplished through the use of an evolved security strategy, PKI, and custom design. Through this paper, descriptions of the migration process and the lessons learned are presented. This will include product decision criteria, rationale, and the use of commodity products in the end architecture. This paper will also stress the need for interoperability of various products and the effects of seemingly insignificant details.

  6. [Analysis on accessibility of urban park green space: the case study of Shenyang Tiexi District].

    PubMed

    Lu, Ning; Li, Jun-Ying; Yan, Hong-Wei; Shi, Tuo; Li, Ying

    2014-10-01

    The accessibility of urban park green space is an important indicator to reflect how much the natural service supplied by parks could be enjoyed by citizens conveniently and fairly. This paper took Shenyang Tiexi District as an example to evaluate the accessibility of urban park green space based on QuickBird imagery and GIS software, with four modes of transportation, walking, non-motor vehicle, motor vehicle and public transport being considered. The research compared and analyzed the distribution of the accessible area and the accessible people of park green space. The result demonstrated that park green space in Shenyang Tiexi District was not enough and the distribution was not even. To be precise, the accessibility in southwest part and central part was relatively good, that in marginal sites was worse, and that in east part and north part was the worst. Furthermore, the accessibility based on different modes of transportation varied a lot. The accessibility of motor vehicle was the best, followed by non-motor vehicle and public transport, and walking was the worst. Most of the regions could be reached within 30 minutes by walking, 15 minutes by non-motor vehicle and public transport, and 10 minutes by motor vehicle. This paper had a realistic significance in terms of further, systematic research on the green space spatial pattern optimization.

  7. Conformation-driven quantum interference effects mediated by through-space conjugation in self-assembled monolayers

    PubMed Central

    Carlotti, Marco; Kovalchuk, Andrii; Wächter, Tobias; Qiu, Xinkai; Zharnikov, Michael; Chiechi, Ryan C.

    2016-01-01

    Tunnelling currents through tunnelling junctions comprising molecules with cross-conjugation are markedly lower than for their linearly conjugated analogues. This effect has been shown experimentally and theoretically to arise from destructive quantum interference, which is understood to be an intrinsic, electronic property of molecules. Here we show experimental evidence of conformation-driven interference effects by examining through-space conjugation in which π-conjugated fragments are arranged face-on or edge-on in sufficiently close proximity to interact through space. Observing these effects in the latter requires trapping molecules in a non-equilibrium conformation closely resembling the X-ray crystal structure, which we accomplish using self-assembled monolayers to construct bottom-up, large-area tunnelling junctions. In contrast, interference effects are completely absent in zero-bias simulations on the equilibrium, gas-phase conformation, establishing through-space conjugation as both of fundamental interest and as a potential tool for tuning tunnelling charge-transport in large-area, solid-state molecular-electronic devices. PMID:27996036

  8. Conformation-driven quantum interference effects mediated by through-space conjugation in self-assembled monolayers

    NASA Astrophysics Data System (ADS)

    Carlotti, Marco; Kovalchuk, Andrii; Wächter, Tobias; Qiu, Xinkai; Zharnikov, Michael; Chiechi, Ryan C.

    2016-12-01

    Tunnelling currents through tunnelling junctions comprising molecules with cross-conjugation are markedly lower than for their linearly conjugated analogues. This effect has been shown experimentally and theoretically to arise from destructive quantum interference, which is understood to be an intrinsic, electronic property of molecules. Here we show experimental evidence of conformation-driven interference effects by examining through-space conjugation in which π-conjugated fragments are arranged face-on or edge-on in sufficiently close proximity to interact through space. Observing these effects in the latter requires trapping molecules in a non-equilibrium conformation closely resembling the X-ray crystal structure, which we accomplish using self-assembled monolayers to construct bottom-up, large-area tunnelling junctions. In contrast, interference effects are completely absent in zero-bias simulations on the equilibrium, gas-phase conformation, establishing through-space conjugation as both of fundamental interest and as a potential tool for tuning tunnelling charge-transport in large-area, solid-state molecular-electronic devices.

  9. Conformation-driven quantum interference effects mediated by through-space conjugation in self-assembled monolayers.

    PubMed

    Carlotti, Marco; Kovalchuk, Andrii; Wächter, Tobias; Qiu, Xinkai; Zharnikov, Michael; Chiechi, Ryan C

    2016-12-20

    Tunnelling currents through tunnelling junctions comprising molecules with cross-conjugation are markedly lower than for their linearly conjugated analogues. This effect has been shown experimentally and theoretically to arise from destructive quantum interference, which is understood to be an intrinsic, electronic property of molecules. Here we show experimental evidence of conformation-driven interference effects by examining through-space conjugation in which π-conjugated fragments are arranged face-on or edge-on in sufficiently close proximity to interact through space. Observing these effects in the latter requires trapping molecules in a non-equilibrium conformation closely resembling the X-ray crystal structure, which we accomplish using self-assembled monolayers to construct bottom-up, large-area tunnelling junctions. In contrast, interference effects are completely absent in zero-bias simulations on the equilibrium, gas-phase conformation, establishing through-space conjugation as both of fundamental interest and as a potential tool for tuning tunnelling charge-transport in large-area, solid-state molecular-electronic devices.

  10. Transformational Technologies to Expedite Space Access and Development

    NASA Astrophysics Data System (ADS)

    Rather, John D. G.

    2010-01-01

    Throughout history the emergence of new technologies has enabled unforeseen breakthrough capabilities that rapidly transformed the world. Some global examples from the twentieth century include AC electric power, nuclear energy, and turbojet engines. At the systems level, success of both Apollo and the Space Shuttle programs depended upon taming hydrogen propulsion and developing high-temperature atmospheric reentry materials. Human space development now is stymied because of a great need for breakthrough technologies and strategies. It is believed that new capabilities exist within the present states-of-the-art of superconducting technology that can be implemented to transform the future of human space development. This paper is an overview of three other papers presented within this forum, which summarizes the principles and consequences of StarTram, showing how the resulting breakthrough advantages can lead directly to safe space tourism and massive development of the moon, Mars and the outer solar system. StarTram can implement cost-effective solar power from space, simple utilization of asteroid material to protect humans from ionizing radiation, and effective defense of the Earth from devastating cosmic impacts. Synergistically, StarTram technologies will revolutionize ground transportation on the Earth, leading to enormous reduction in energy consumption and creation of millions of jobs. High energy lasers will also be discussed because of their importance to power beaming applications.

  11. Transformational Technologies to Expedite Space Access and Development

    SciTech Connect

    Rather, John D. G.

    2010-01-28

    Throughout history the emergence of new technologies has enabled unforeseen breakthrough capabilities that rapidly transformed the world. Some global examples from the twentieth century include AC electric power, nuclear energy, and turbojet engines. At the systems level, success of both Apollo and the Space Shuttle programs depended upon taming hydrogen propulsion and developing high-temperature atmospheric reentry materials. Human space development now is stymied because of a great need for breakthrough technologies and strategies. It is believed that new capabilities exist within the present states-of-the-art of superconducting technology that can be implemented to transform the future of human space development. This paper is an overview of three other papers presented within this forum, which summarizes the principles and consequences of StarTram, showing how the resulting breakthrough advantages can lead directly to safe space tourism and massive development of the moon, Mars and the outer solar system. StarTram can implement cost-effective solar power from space, simple utilization of asteroid material to protect humans from ionizing radiation, and effective defense of the Earth from devastating cosmic impacts. Synergistically, StarTram technologies will revolutionize ground transportation on the Earth, leading to enormous reduction in energy consumption and creation of millions of jobs. High energy lasers will also be discussed because of their importance to power beaming applications.

  12. America’s Access to Space: Assuring Future Affordability

    DTIC Science & Technology

    2010-12-01

    multinational endeavor established in 1995 between The Boeing Company’s Space Systems, Russia’s RSC- Energia , Norway’s Aker Kvaerner, and Ukrainian’s...50 The Sea Launch system centers around the Zenit-3SL rocket system built cooperatively between Russia’s RSC Energia , the Ukraine’s SDO

  13. Enabling Dedicated, Affordable Space Access Through Aggressive Technology Maturation

    NASA Technical Reports Server (NTRS)

    Jones, Jonathan E.; Kibbey, Timothy P.; Cobb, C. Brent; Harris, Lawanna L.

    2014-01-01

    A launch vehicle at the scale and price point which allows developers to take reasonable risks with high payoff propulsion and avionics hardware solutions does not exist today. Establishing this service provides a ride through the proverbial technology "valley of death" that lies between demonstration in laboratory and flight environments. NASA's NanoLaunch effort will provide the framework to mature both earth-to-orbit and on-orbit propulsion and avionics technologies while also providing affordable, dedicated access to low earth orbit for cubesat class payloads.

  14. SLAC All Access: Fermi Gamma-ray Space Telescope

    SciTech Connect

    Romani, Roger

    2013-05-31

    Three hundred and fifty miles overhead, the Fermi Gamma-ray Space Telescope silently glides through space. From this serene vantage point, the satellite's instruments watch the fiercest processes in the universe unfold. Pulsars spin up to 700 times a second, sweeping powerful beams of gamma-ray light through the cosmos. The hyperactive cores of distant galaxies spew bright jets of plasma. Far beyond, something mysterious explodes with unfathomable power, sending energy waves crashing through the universe. Stanford professor and KIPAC member Roger W. Romani talks about this orbiting telescope, the most advanced ever to view the sky in gamma rays, a form of light at the highest end of the energy spectrum that's created in the hottest regions of the universe.

  15. SLAC All Access: Fermi Gamma-ray Space Telescope

    ScienceCinema

    Romani, Roger

    2016-07-12

    Three hundred and fifty miles overhead, the Fermi Gamma-ray Space Telescope silently glides through space. From this serene vantage point, the satellite's instruments watch the fiercest processes in the universe unfold. Pulsars spin up to 700 times a second, sweeping powerful beams of gamma-ray light through the cosmos. The hyperactive cores of distant galaxies spew bright jets of plasma. Far beyond, something mysterious explodes with unfathomable power, sending energy waves crashing through the universe. Stanford professor and KIPAC member Roger W. Romani talks about this orbiting telescope, the most advanced ever to view the sky in gamma rays, a form of light at the highest end of the energy spectrum that's created in the hottest regions of the universe.

  16. Concept for Multiple-Access Free-Space Laser Communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith

    2004-01-01

    A design concept for a proposed airborne or spaceborne free-space optical-communication terminal provides for simultaneous reception of signals from multiple other opticalcommunication terminals aboard aircraft or spacecraft that carry scientific instruments and fly at lower altitudes. The concept reflects the need for rapid acquisition and tracking of the signals coming from the lower-altitude terminals as they move across the field of view.

  17. Probing molecular conformations in momentum space: The case of n-pentane

    NASA Astrophysics Data System (ADS)

    Knippenberg, S.; Huang, Y. R.; Hajgató, B.; François, J.-P.; Deng, J. K.; Deleuze, M. S.

    2007-11-01

    A comprehensive study, throughout the valence region, of the electronic structure and electron momentum density distributions of the four conformational isomers of n-pentane is presented. Theoretical (e,2e) valence ionization spectra at high electron impact energies (1200eV+electron binding energy) and at azimuthal angles ranging from 0° to 10° in a noncoplanar symmetric kinematical setup are generated according to the results of large scale one-particle Green's function calculations of Dyson orbitals and related electron binding energies, using the third-order algebraic-diagrammatic construction [ADC(3)] scheme. The results of a focal point analysis (FPA) of relative conformer energies [A. Salam and M. S. Deleuze, J. Chem. Phys. 116, 1296 (2002)] and improved thermodynamical calculations accounting for hindered rotations are also employed in order to quantitatively evaluate the abundance of each conformer in the gas phase at room temperature and reliably predict the outcome of experiments on n-pentane employing high resolution electron momentum spectroscopy. Comparison with available photoelectron measurements confirms the suggestion that, due to entropy effects, the trans-gauche (tg) conformer strongly dominates the conformational mixture characterizing n-pentane at room temperature. Our simulations demonstrate therefore that experimental measurements of (e,2e) valence ionization spectra and electron momentum distributions would very consistently and straightforwardly image the topological changes and energy variations that molecular orbitals undergo due to torsion of the carbon backbone. The strongest fingerprints for the most stable conformer (tt) are found for the electron momentum distributions associated with ionization channels at the top of the inner-valence region, which sensitively image the development of methylenic hyperconjugation in all-staggered n-alkane chains.

  18. Conformally related massless fields in dS, AdS and Minkowski spaces

    SciTech Connect

    Huguet, E.; Queva, J.; Renaud, J.

    2006-04-15

    In this paper we write down the equation for a scalar conformally coupled field simultaneously for de Sitter (dS), anti-de Sitter (AdS), and Minkowski spacetimes in d dimensions. The curvature dependence appears in a very simple way through a conformal factor. As a consequence the process of curvature free limit, including wave functions limit and two-points functions, turns out to be a straightforward issue. We determine a set of modes, that we call de Sitter plane waves, which become ordinary plane waves when the curvature vanishes.

  19. REUSABLE PROPULSION ARCHITECTURE FOR SUSTAINABLE LOW-COST ACCESS TO SPACE

    NASA Technical Reports Server (NTRS)

    Bonometti, J. A.; Dankanich, J. W.; Frame, K. L.

    2005-01-01

    The primary obstacle to any space-based mission is, and has always been, the cost of access to space. Even with impressive efforts toward reusability, no system has come close to lowering the cost a significant amount. It is postulated here, that architectural innovation is necessary to make reusability feasible, not incremental subsystem changes. This paper shows two architectural approaches of reusability that merit further study investments. Both #inherently# have performance increases and cost advantages to make affordable access to space a near term reality. A rocket launched from a subsonic aircraft (specifically the Crossbow methodology) and a momentum exchange tether, reboosted by electrodynamics, offer possibilities of substantial reductions in the total transportation architecture mass - making access-to-space cost-effective. They also offer intangible benefits that reduce risk or offer large growth potential. The cost analysis indicates that approximately a 50% savings is obtained using today#s aerospace materials and practices.

  20. Efficient sampling of protein conformational space using fast loop building and batch minimization on highly parallel computers.

    PubMed

    Tyka, Michael D; Jung, Kenneth; Baker, David

    2012-12-05

    All-atom sampling is a critical and compute-intensive end stage to protein structural modeling. Because of the vast size and extreme ruggedness of conformational space, even close to the native structure, the high-resolution sampling problem is almost as difficult as predicting the rough fold of a protein. Here, we present a combination of new algorithms that considerably speed up the exploration of very rugged conformational landscapes and are capable of finding heretofore hidden low-energy states. The algorithm is based on a hierarchical workflow and can be parallelized on supercomputers with up to 128,000 compute cores with near perfect efficiency. Such scaling behavior is notable, as with Moore's law continuing only in the number of cores per chip, parallelizability is a critical property of new algorithms. Using the enhanced sampling power, we have uncovered previously invisible deficiencies in the Rosetta force field and created an extensive decoy training set for optimizing and testing force fields.

  1. Space Vision: Making Astronomy Accessible to Visually Impaired Students

    NASA Astrophysics Data System (ADS)

    Ries, J. G.; Baguio, M. R.; Jurgens, T. D.; Pruett, K. M.

    2004-05-01

    Astronomy, with good reason, is thought of as a visual science. Spectacular images of deep space objects or other worlds of our solar system inspire public interest in Astronomy. People encounter news about the universe during their daily life. Developing concepts about celestial objects presents an extra challenge of abstraction for people with visual impairments. The Texas Space Grant Consortium with educators at the Texas School for the Blind and Visually Impaired have developed a 2 day workshop to be held in April 2004 to help students with visual impairments understand these concepts. Hands-on activities and experiments will emphasize non-visual senses. For example, students will learn about: - Constellations as historical ways of finding one's way across the sky. - The size and structure of the Solar System by building a scale model on a running track. They will also: - Plan a planetary exploration mission. - Explore wave phenomenon using heat and sound waves. In preparation for the workshop we worked with teens involved in the countywide 4-H Teens Leading with Character (TLC) program to create the tactile materials necessary for the activities. The teens attended solar system education training so they would have the skills necessary to make the tactile displays to be used during the workshop. The results and evaluation of the workshop will be presented at the meeting. Touch the Universe: A NASA Braille Book of Astronomy inspired this workshop, and it is supported by HST Grant HST-ED-90255.01-A.

  2. Conformal flight path symbology for head-up displays: Defining the distribution of visual attention in three-dimensional space

    NASA Astrophysics Data System (ADS)

    Ververs, Patricia May

    experimental findings. Attention was found to be more widely distributed in X-Y space when the pilots were flying with the conformal, tunnel-in-the-sky as compared to the partially conformal ILS (instrument landing system) symbology set. There was little evidence that the air-based navigation displays were supporting divided attention in three-dimensional space. The ground-based scene-linked (truly conformal) display indicated promising effects of dividing attention in depth without negative consequences to processing the near domain symbology. Event expectancy was found to modulate pilot performance in the detection of events both on the symbology and in the environment. The phenomenon known as cognitive tunneling is discussed as a possible cause of the inadequate response times in resolving the anomalous events.

  3. Retroperitoneal Laparoscopy in Dogs: Access Technique, Working Space, and Surgical Anatomy

    PubMed Central

    Jeong, Junemoe; Ko, Jonghyeok; Lim, Hyunjoo; Kweon, Oh‐Kyeong

    2016-01-01

    Objective To develop and describe a laparoscopic retroperitoneal access technique, investigate working space establishment, and describe the surgical anatomy in the retroperitoneal space as an initial step for clinical application of retroperitoneal laparoscopy in dogs. Study Design Cadaveric and experimental study. Animals Cadaveric (n=8) and healthy (n=6) adult dogs. Methods The retroperitoneal access technique was developed in 3 cadavers based on the human technique and transperitoneal observation. Its application and working space establishment with carbon dioxide (CO2) insufflation alone was evaluated in 5 cadavers by observing with a transperitoneal telescope and in 6 live dogs by repeated computed tomography (CT) scans at pressure of 0, 5, 10, and 15 mmHg. Recordings of retroperitoneoscopy as well as working space volume and linear dimensions measured on CT images were analyzed. Results Retroperitoneal access and working space establishment with CO2 insufflation alone were successfully performed in all 6 live dogs. The only complication observed was in 1 dog that developed subclinical pneumomediastinum. As pressure increased, working space was established from the ipsilateral to the contralateral side, and peritoneal tearing eventually developed. Working space volume increased significantly from 5 mmHg and linear dimensions increased significantly from 0 to 10 mmHg. With pneumo‐retroperitoneum above 5 mmHg, retroperitoneal organs, including kidneys and adrenal glands, were easily visualized. Conclusion The retroperitoneal access technique and working space establishment with CO2 insufflation starting with 5 mmHg and increasing to 10 mmHg provided adequate working space and visualization of retroperitoneal organs, which may allow direct access for retroperitoneal laparoscopy in dogs. PMID:27731512

  4. Considerations on private human access to space from an institutional point of view

    NASA Astrophysics Data System (ADS)

    Hufenbach, Bernhard

    2013-12-01

    Private human access to space as discussed in this article addresses two market segments: suborbital flight and crew flights to Low Earth Orbit. The role of entrepreneurs, the technical complexity, the customers, the market conditions as well as the time to market in these two segments differ significantly. Space agencies take currently a very different approach towards private human access to space in both segments. Analysing the outcome of broader inter-agency deliberations on the future of human spaceflight and exploration, performed e.g. in the framework of the International Space Exploration Coordination Group, enables to derive some common general views on this topic. Various documents developed by inter-agency working groups recognise the general strategic importance for enabling private human access to space for ensuring a sustainable future of human spaceflight, although the specific definition of private human access and approaches vary. ESA has performed some reflections on this subject throughout the last 5 years. While it gained through these reflections a good understanding on the opportunities and implications resulting from the development of capabilities and markets for Private Human Access, limited concrete activities have been initiated in relation to this topic as of today.

  5. A global conformal extension theorem for perfect fluid Bianchi space-times

    SciTech Connect

    Luebbe, Christian Tod, Paul

    2008-12-15

    A global extension theorem is established for isotropic singularities in polytropic perfect fluid Bianchi space-times. When an extension is possible, the limiting behaviour of the physical space-time near the singularity is analysed.

  6. The space of access to primary mental health care: a qualitative case study.

    PubMed

    Kovandžić, Marija; Funnell, Emma; Hammond, Jonathan; Ahmed, Abdi; Edwards, Suzanne; Clarke, Pam; Hibbert, Derek; Bristow, Katie; Dowrick, Christopher

    2012-05-01

    Guided by theoretical perspectives of relational social science, this paper draws on reanalyses of multiple qualitative datasets related to a multi-ethnic, economically disadvantaged area in Liverpool, UK, with the aim to advance general understanding of access to primary mental health care while using local Somali minority as an instrumental focus. The findings generate a novel concept: the space of access. The shape and dynamics of the space of access are determined by at least four fields of tensions: understandings of area and community; cognitive mapping of mental well-being, illness and care; positioning of primary care services; and dynamics of resources beyond the 'medical zone' of care. The conclusions indicate a need for de-centring and re-connecting the role of medical professionals within primary care which itself needs to be transformed by endorsement of multiple avenues of access to diverse support and intrepid communication among all involved actors.

  7. The Non-linear Schrödinger Equation and the Conformal Properties of Non-relativistic Space-Time

    NASA Astrophysics Data System (ADS)

    Horváthy, P. A.; Yera, J.-C.

    2009-08-01

    The cubic non-linear Schrödinger equation where the coefficient of the nonlinear term is a function F(t,x) only passes the Painlevé test of Weiss, Tabor, and Carnevale only for F=(a+bt)-1, where a and b are constants. This is explained by transforming the time-dependent system into the constant-coefficient NLS by means of a time-dependent non-linear transformation, related to the conformal properties of non-relativistic space-time. A similar argument explains the integrability of the NLS in a uniform force field or in an oscillator background.

  8. Conformational space of clindamycin studied by ab initio and full-atom molecular dynamics.

    PubMed

    Kulczycka-Mierzejewska, Katarzyna; Trylska, Joanna; Sadlej, Joanna

    2016-01-01

    Molecular dynamics (MD) simulations allow determining internal flexibility of molecules at atomic level. Using ab initio Born-Oppenheimer molecular dynamics (BOMD), one can simulate in a reasonable time frame small systems with hundreds of atoms, usually in vacuum. With quantum mechanics/molecular mechanics (QM/MM) or full-atom molecular dynamics (FAMD), the influence of the environment can also be simulated. Here, we compare three types of MD calculations: ab initio BOMD, hybrid QM/MM, and classical FAMD. As a model system, we use a small antibiotic molecule, clindamycin, which is one of the lincosamide antibiotics. Clindamycin acquires two energetically stable forms and we investigated the transition between these two experimentally known conformers. We performed 60-ps BOMD simulations in vacuum, 50-ps QM/MM, and 100-ns FAMD in explicit water. The transition between two antibiotic conformers was observed using both BOMD and FAMD methods but was not noted in the QM/MM simulations.

  9. Conformational Space and Stability of ETD Charge Reduction Products of Ubiquitin

    NASA Astrophysics Data System (ADS)

    Lermyte, Frederik; Łącki, Mateusz Krzysztof; Valkenborg, Dirk; Gambin, Anna; Sobott, Frank

    2017-01-01

    Owing to its versatility, electron transfer dissociation (ETD) has become one of the most commonly utilized fragmentation techniques in both native and non-native top-down mass spectrometry. However, several competing reactions—primarily different forms of charge reduction—occur under ETD conditions, as evidenced by the distorted isotope patterns usually observed. In this work, we analyze these isotope patterns to compare the stability of nondissociative electron transfer (ETnoD) products, specifically noncovalent c/ z fragment complexes, across a range of ubiquitin conformational states. Using ion mobility, we find that more extended states are more prone to fragment release. We obtain evidence that for a given charge state, populations of ubiquitin ions formed either directly by electrospray ionization or through collapse of more extended states upon charge reduction, span a similar range of collision cross-sections. Products of gas-phase collapse are, however, less stabilized towards unfolding than the native conformation, indicating that the ions retain a memory of previous conformational states. Furthermore, this collapse of charge-reduced ions is promoted if the ions are `preheated' using collisional activation, with possible implications for the kinetics of gas-phase compaction.

  10. Sampling the conformational space of the catalytic subunit of human γ-secretase

    PubMed Central

    Bai, Xiao-chen; Rajendra, Eeson; Yang, Guanghui; Shi, Yigong; Scheres, Sjors HW

    2015-01-01

    Human γ-secretase is an intra-membrane protease that cleaves many different substrates. Aberrant cleavage of Notch is implicated in cancer, while abnormalities in cutting amyloid precursor protein lead to Alzheimer's disease. Our previous cryo-EM structure of γ-secretase revealed considerable disorder in its catalytic subunit presenilin. Here, we describe an image classification procedure that characterizes molecular plasticity at the secondary structure level, and apply this method to identify three distinct conformations in our previous sample. In one of these conformations, an additional transmembrane helix is visible that cannot be attributed to the known components of γ-secretase. In addition, we present a γ-secretase structure in complex with the dipeptidic inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). Our results reveal how conformational mobility in the second and sixth transmembrane helices of presenilin is greatly reduced upon binding of DAPT or the additional helix, and form the basis for a new model of how substrate enters the transmembrane domain. DOI: http://dx.doi.org/10.7554/eLife.11182.001 PMID:26623517

  11. Astronaut Ross Approaches Assembly Concept for Construction of Erectable Space Structure (ACCESS)

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The crew assigned to the STS-61B mission included Bryan D. O'Conner, pilot; Brewster H. Shaw, commander; Charles D. Walker, payload specialist; mission specialists Jerry L. Ross, Mary L. Cleave, and Sherwood C. Spring; and Rodolpho Neri Vela, payload specialist. Launched aboard the Space Shuttle Atlantis November 28, 1985 at 7:29:00 pm (EST), the STS-61B mission's primary payload included three communications satellites: MORELOS-B (Mexico); AUSSAT-2 (Australia); and SATCOM KU-2 (RCA Americom). Two experiments were conducted to test assembling erectable structures in space: EASE (Experimental Assembly of Structures in Extravehicular Activity), and ACCESS (Assembly Concept for Construction of Erectable Space Structure). In a joint venture between NASA/Langley Research Center in Hampton, Virginia, and the Marshall Space Flight Center (MSFC), EASE and ACCESS were developed and demonstrated at MSFC's Neutral Buoyancy Simulator (NBS). In this STS-61B onboard photo, astronaut Ross, perched on the Manipulator Foot Restraint (MFR) approaches the erected ACCESS. The primary objective of these experiments was to test the structural assembly concepts for suitability as the framework for larger space structures and to identify ways to improve the productivity of space construction.

  12. Nanotube structures, methods of making nanotube structures, and methods of accessing intracellular space

    DOEpatents

    VanDersarl, Jules J.; Xu, Alexander M.; Melosh, Nicholas A.; Tayebi, Noureddine

    2016-02-23

    In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, embodiments of the present disclosure, in one aspect, relate to methods of making a structure including nanotubes, a structure including nanotubes, methods of delivering a fluid to a cell, methods of removing a fluid to a cell, methods of accessing intracellular space, and the like.

  13. The physical determinants of the DNA conformational landscape: an analysis of the potential energy surface of single-strand dinucleotides in the conformational space of duplex DNA

    PubMed Central

    Elsawy, Karim M.; Hodgson, Michael K.; Caves, Leo S. D.

    2005-01-01

    A multivariate analysis of the backbone and sugar torsion angles of dinucleotide fragments was used to construct a 3D principal conformational subspace (PCS) of DNA duplex crystal structures. The potential energy surface (PES) within the PCS was mapped for a single-strand dinucleotide model using an empirical energy function. The low energy regions of the surface encompass known DNA forms and also identify previously unclassified conformers. The physical determinants of the conformational landscape are found to be predominantly steric interactions within the dinucleotide backbone, with medium-dependent backbone-base electrostatic interactions serving to tune the relative stability of the different local energy minima. The fidelity of the PES to duplex DNA properties is validated through a correspondence to the conformational distribution of duplex DNA crystal structures and the reproduction of observed sequence specific propensities for the formation of A-form DNA. The utility of the PES is demonstrated through its succinct and accurate description of complex conformational processes in simulations of duplex DNA. The study suggests that stereochemical considerations of the nucleic acid backbone play a role in determining conformational preferences of DNA which is analogous to the role of local steric interactions in determining polypeptide secondary structure. PMID:16214808

  14. Making Astronomy and Space Science Accessible to the Blind and Visually Impaired

    NASA Astrophysics Data System (ADS)

    Beck-Winchatz, B.; Hoette, V.; Grice, N.

    2003-12-01

    One of the biggest obstacles blind and visually impaired people face in science is the ubiquity of important graphical information, which is generally not made available in alternate formats accessible to them. Funded by NASA's Initiative to Develop Education through Astronomy and Space Science (IDEAS), we have recently formed a team of scientists and educators from universities, the SOFIA NASA mission, a science museum, an observatory, and schools for the blind. Our goal is to develop and test Braille/tactile space science activities that actively engage students from elementary grades through introductory college-level in space science. We will discuss effective strategies and low-cost technologies that can be used to make graphical information accessible. We will also demonstrate examples, such a thermal expansion graphics created from telescope images of the Moon and other celestial objects, a tactile planisphere, three-dimensional models of near-Earth asteroids and tactile diagrams of their orbits, and an infrared detector activity.

  15. The Virtual Space Physics Observatory: Quick Access to Data and Tools

    NASA Technical Reports Server (NTRS)

    Cornwell, Carl; Roberts, D. Aaron; McGuire, Robert E.

    2006-01-01

    The Virtual Space Physics Observatory (VSPO; see http://vspo.gsfc.nasa.gov) has grown to provide a way to find and access about 375 data products and services from over 100 spacecraft/observatories in space and solar physics. The datasets are mainly chosen to be the most requested, and include most of the publicly available data products from operating NASA Heliophysics spacecraft as well as from solar observatories measuring across the frequency spectrum. Service links include a "quick orbits" page that uses SSCWeb Web Services to provide a rapid answer to questions such as "What spacecraft were in orbit in July 1992?" and "Where were Geotail, Cluster, and Polar on 2 June 2001?" These queries are linked back to the data search page. The VSPO interface provides many ways of looking for data based on terms used in a registry of resources using the SPASE Data Model that will be the standard for Heliophysics Virtual Observatories. VSPO itself is accessible via an API that allows other applications to use it as a Web Service; this has been implemented in one instance using the ViSBARD visualization program. The VSPO will become part of the Space Physics Data Facility, and will continue to expand its access to data. A challenge for all VOs will be to provide uniform access to data at the variable level, and we will be addressing this question in a number of ways.

  16. Time-independent bounds on solutions with shocks to the relativistic Euler equations on conformally flat space-times with curvature singularities

    NASA Astrophysics Data System (ADS)

    Groah, Jeffrey M.

    1998-12-01

    We consider the initial value problem of the relativistic Euler equations when the underlying space-time is not flat but conformally flat, and demonstrate existence of solutions with shocks, with time-independent bounds, in some cases from big bang till big crunch. Our theorem requires that the space-time metric satisfy certain bounds, but these do not constrain the curvature of space-time, and hence our theorem may guarantee uniform bounds on solutions until the formation of curvature singularities.

  17. Test of the Anti-de Sitter-Space/Conformal-Field-Theory Correspondence Using High-Spin Operators

    SciTech Connect

    Benna, M. K.; Benvenuti, S.; Klebanov, I. R.; Scardicchio, A.

    2007-03-30

    In two remarkable recent papers the planar perturbative expansion was proposed for the universal function of the coupling appearing in the dimensions of high-spin operators of the N=4 super Yang-Mills theory. We study numerically the integral equation derived by Beisert, Eden, and Staudacher, which resums the perturbative series. In a confirmation of the anti-de Sitter-space/conformal-field-theory (AdS/CFT) correspondence, we find a smooth function whose two leading terms at strong coupling match the results obtained for the semiclassical folded string spinning in AdS{sub 5}. We also make a numerical prediction for the third term in the strong coupling series.

  18. Multiple Simulated Annealing-Molecular Dynamics (MSA-MD) for Conformational Space Search of Peptide and Miniprotein.

    PubMed

    Hao, Ge-Fei; Xu, Wei-Fang; Yang, Sheng-Gang; Yang, Guang-Fu

    2015-10-23

    Protein and peptide structure predictions are of paramount importance for understanding their functions, as well as the interactions with other molecules. However, the use of molecular simulation techniques to directly predict the peptide structure from the primary amino acid sequence is always hindered by the rough topology of the conformational space and the limited simulation time scale. We developed here a new strategy, named Multiple Simulated Annealing-Molecular Dynamics (MSA-MD) to identify the native states of a peptide and miniprotein. A cluster of near native structures could be obtained by using the MSA-MD method, which turned out to be significantly more efficient in reaching the native structure compared to continuous MD and conventional SA-MD simulation.

  19. The ESPAS e-infrastructure: Access to data from near-Earth space

    NASA Astrophysics Data System (ADS)

    Belehaki, Anna; James, Sarah; Hapgood, Mike; Ventouras, Spiros; Galkin, Ivan; Lembesis, Antonis; Tsagouri, Ioanna; Charisi, Anna; Spogli, Luca; Berdermann, Jens; Häggström, Ingemar

    2016-10-01

    ESPAS, the "near-Earth space data infrastructure for e-science" is a data e-infrastructure facilitating discovery and access to observations, ground-based and space borne, and to model predictions of the near-Earth space environment, a region extending from the Earth's atmosphere up to the outer radiation belts. ESPAS provides access to metadata and/or data from an extended network of data providers distributed globally. The interoperability of the heterogeneous data collections is achieved with the adoption and adaption of the ESPAS data model which is built entirely on ISO 19100 series geographic information standards. The ESPAS data portal manages a vocabulary of space physics keywords that can be used to narrow down data searches to observations of specific physical content. Such content-targeted search is an ESPAS innovation provided in addition to the commonly practiced data selection by time, location, and instrument. The article presents an overview of the architectural design of the ESPAS system, of its data model and ontology, and of interoperable services that allow the discovery, access and download of registered data. Emphasis is given to the standardization, and expandability concepts which represent also the main elements that support the building of long-term sustainability activities of the ESPAS e-infrastructure.

  20. URSA MAIOR: a One Liter Nanosatellite Bus for Low Cost Access to Space

    NASA Astrophysics Data System (ADS)

    Santoni, F.

    One of the main limitations in the access to space for developing countries is the economical effort typically required by space missions. Secondly, space activity is a field of very high technology, requiring technical skills, education and practice, at a level which is seldom reached by developing countries. Interventions aimed to facilitate access to space for developing countries should be focussed primarily on the missions allowing access to space at reasonable cost. Moreover, perhaps more importantly, they should emphasize conducting the mission design, construction, ground testing and operation in orbit as an open activity, accessible to developing countries personnel, in order to set up an education process, which is not just selling a product ready satellite. Universities could have a very important role in this activity. Many Universities around the world have designed, built and launched small satellites. Università di Roma "La Sapienza" set up a program for the construction of small satellites in an academic environment, involving directly the students in the design, construction, ground testing and operation in orbit. The first satellite built in the framework of this program, UNISAT, was successfully launched in September 2000. The second, UNISAT-2, initially scheduled for launch in 2001, has been delayed by the launch provider to late 2002. These two satellites, based on a modular design, emphasizing ease of construction and assembly, weight roughly 10 kg. The realization of these satellites was made possible within the regular financing given to university research programs, keeping down cost by the use of commercial off the shelf components instead of space rated ones. The microsatellite experience at Università di Roma "La Sapienza", is going further with the development of a new nanosatellite bus, URSA MAIOR (Università di Roma "la SApienza" Micro Autonomous Imager in ORbit), aiming at cutting down cost and possibly improving performance. The

  1. Random Access Frames (RAF): Alternative to Rack and Standoff for Deep Space Habitat Outfitting

    NASA Technical Reports Server (NTRS)

    Howe, A. Scott; Polit-Casillas, Raul

    2014-01-01

    A modular Random Access Frame (RAF) system is proposed as an alternative to the International Standard Payload Rack (ISPR) for internal module layout and outfitting in a Deep Space Habitat (DSH). The ISPR approach was designed to allow for efficient interchangeability of payload and experiments for the International Space Station (ISS) when frequent resupply missions were available (particularly the now-retired Space Shuttle). Though the standard interface approach to the ISPR system allowed integration of subsystems and hardware from a variety of sources and manufacturers, the heavy rack and standoff approach may not be appropriate when resupply or swap-out capabilities are not available, such as on deep space, long-duration missions. The lightweight RAF concept can allow a more dense packing of stowage and equipment, and may be easily broken down for repurposing or reuse. Several example layouts and workstations are presented.

  2. Conformationally Constrained Histidines in the Design of Peptidomimetics: Strategies for the χ-Space Control

    PubMed Central

    Stefanucci, Azzurra; Pinnen, Francesco; Feliciani, Federica; Cacciatore, Ivana; Lucente, Gino; Mollica, Adriano

    2011-01-01

    A successful design of peptidomimetics must come to terms with χ-space control. The incorporation of χ-space constrained amino acids into bioactive peptides renders the χ1 and χ2 torsional angles of pharmacophore amino acids critical for activity and selectivity as with other relevant structural features of the template. This review describes histidine analogues characterized by replacement of native α and/or β-hydrogen atoms with alkyl substituents as well as analogues with α, β-didehydro unsaturation or Cα-Cβ cyclopropane insertion (ACC derivatives). Attention is also dedicated to the relevant field of β-aminoacid chemistry by describing the synthesis of β2- and β3-models (β-hHis). Structural modifications leading to cyclic imino derivatives such as spinacine, aza-histidine and analogues with shortening or elongation of the native side chain (nor-histidine and homo-histidine, respectively) are also described. Examples of the use of the described analogues to replace native histidine in bioactive peptides are also given. PMID:21686155

  3. Accessibility

    EPA Pesticide Factsheets

    Federal laws, including Section 508 of the Rehabilitation Act, mandate that people with disabilities have access to the same information that someone without a disability would have. 508 standards cover electronic and information technology (EIT) products.

  4. Rocket-Based Combined-Cycle Propulsion Technology for Access-to-Space Applications

    NASA Technical Reports Server (NTRS)

    Hueter, Uwe

    1999-01-01

    NASA's Office of Aero-Space Technology (OAST) established three major goals, referred to as, "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala. focuses on future space transportation technologies under the "Access to Space" pillar. One of the main activities over the past three years has been on advancing the hydrogen fueled rocket-based combined cycle (RBCC) technologies. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion. Aerojet and Boeing-Rocketdyne designed, built and ground tested their RBCC engine concepts. In addition, ASTROX, Georgia Institute of Technology, McKinney Associates, Pennsylvania State University (PSU), and University of Alabama in Huntsville conducted supporting activities. The RBCC activity included ground testing of components (e.g., injectors, thrusters, ejectors and inlets) and integrated flowpaths. Inlet testing was performed at the Lewis Research Center's 1 x 1 wind tunnel. All direct connect and free-jet engine testing were conducted at the GASL facilities on Long Island, New York. Testing spanned the Mach range from sea level static to Mach 8. Testing of the rocket-only mode, simulating the final phase of the ascent mission profile, was also performed. The originally planned work on these contracts was completed in 1999. Follow-on activities have been initiated for both hydrogen and hydrocarbon fueled RBCC concepts. Studies to better understand system level issues with the integration of RBCC propulsion with earth-to-orbit vehicles have also been conducted. This paper describes the status, progress and future plans of the RBCC activities funded by NASA/MSFC with a major focus on the benefits of utilizing air-breathing combined-cycle propulsion in access-to-space applications.

  5. Conformational disorder of proteins assessed by real-space molecular dynamics refinement.

    PubMed Central

    Chen, Z; Chapman, M S

    2001-01-01

    Motion is critical to the function of many proteins, but much more difficult to study than structure. Due to lack of easy alternatives, although there are inherent limitations, there have been several prior attempts to extract some information from the Bragg scattering in conventional diffraction patterns. Bragg diffraction reflects only a small proportion of a protein's motion and disorder, so fitted values likely underestimate reality. However, this work shows that the fitted estimates should be even smaller, because current methods of refinement over-fit the Bragg diffraction, leading to a component of the disorder that is not based on any experimental data, and could be characterized as a guess. Real-space refinement is less susceptible than other methods, but its application depends on the availability of very accurate experimental phases. A future challenge will be the collection of such data without resort to cryo-techniques, so that a physiologically relevant understanding can be achieved. PMID:11222306

  6. Exploring the Unknown: Selected Documents in the History of the U.S. Civil Space Program. Volume 4; Accessing Space

    NASA Technical Reports Server (NTRS)

    Logsdon, John M. (Editor); Williamson, Ray A. (Editor); Launius, Roger D. (Editor); Acker, Russell J. (Editor); Garber, Stephen J. (Editor); Friedman, Jonathan L. (Editor)

    1999-01-01

    The documents selected for inclusion in this volume are presented in four major chapters, each covering a particular aspect of access to space and the manner in which it has developed over time. These chapters focus on the evolution toward the giant Saturn V rocket, the development of the Space Shuttle, space transportation commercialization, and future space transportation possibilities. Each chapter in this volume is introduced by an overview essay, prepared by individuals who are particularly well qualified to write on the topic. In the main, these essays are intended to introduce and complement the documents in the chapter and to place them, for the most part, in a chronological and substantive context. Each essay contains references to the documents in the chapter it introduces, and many also contain references to documents in other chapters of the collection. These introductory essays are the responsibility of their individual authors, and the views and conclusions contained therein do not necessarily represent the opinions of either George Washington University or NASA.

  7. The Ares I Crew Launch Vehicle: Human Space Access for the Moon and Beyond

    NASA Technical Reports Server (NTRS)

    Cook, Stephen A.

    2008-01-01

    The National Aeronautics and Space Administration (NASA)'s Constellation Program is depending on the Ares Projects to deliver the crew launch capabilities needed to send human explorers to the Moon and beyond. The Ares Projects continue to make progress toward design, component testing, and early flight testing of the Ares I crew launch vehicle (Figure 1), the United States first new human-rated launch vehicle in over 25 years. Ares I will provide the core space launch capabilities the United States needs to continue providing crew and cargo access to the International Space Station (ISS), maintaining the U.S. pioneering tradition as a spacefaring nation, and enabling cooperative international ventures to the Moon and beyond. This paper will discuss programmatic, design, fabrication, and testing progress toward building this new launch vehicle.

  8. Accessing space: A catalogue of process, equipment and resources for commercial users

    NASA Technical Reports Server (NTRS)

    1988-01-01

    This catalogue, produced by NASA's Office of Commercial Programs, provides a broad source of information for the commercial developer interested in the areas of microgravity research and remote sensing. Methods for accessing space for research are reviewed including the shuttle, expendable launch vehicles, suborbital sounding rockets, experimental aircraft, and drop towers and other ground-based facilities. Procedures for using these vehicles and facilities are described along with funding options to pay for their use. Experiment apparatus and carriers for microgravity research are also described. A separate directory of resources and services is also included which contains a listing of transportation products and services, a listing of businesses and industries which provide space-related services and products, and a listing of the NASA and CCDS (Center for the Commercial Development of Space) points of contact.

  9. Interoperative fundus image and report sharing in compliance with integrating the healthcare enterprise conformance and web access to digital imaging and communication in medicine persistent object protocol

    PubMed Central

    Wu, Hui-Qun; Lv, Zheng-Min; Geng, Xing-Yun; Jiang, Kui; Tang, Le-Min; Zhou, Guo-Min; Dong, Jian-Cheng

    2013-01-01

    AIM To address issues in interoperability between different fundus image systems, we proposed a web eye-picture archiving and communication system (PACS) framework in conformance with digital imaging and communication in medicine (DICOM) and health level 7 (HL7) protocol to realize fundus images and reports sharing and communication through internet. METHODS Firstly, a telemedicine-based eye care work flow was established based on integrating the healthcare enterprise (IHE) Eye Care technical framework. Then, a browser/server architecture eye-PACS system was established in conformance with the web access to DICOM persistent object (WADO) protocol, which contains three tiers. RESULTS In any client system installed with web browser, clinicians could log in the eye-PACS to observe fundus images and reports. Multipurpose internet mail extensions (MIME) type of a structured report is saved as pdf/html with reference link to relevant fundus image using the WADO syntax could provide enough information for clinicians. Some functions provided by open-source Oviyam could be used to query, zoom, move, measure, view DICOM fundus images. CONCLUSION Such web eye-PACS in compliance to WADO protocol could be used to store and communicate fundus images and reports, therefore is of great significance for teleophthalmology. PMID:24392341

  10. Ethernet access network based on free-space optic deployment technology

    NASA Astrophysics Data System (ADS)

    Gebhart, Michael; Leitgeb, Erich; Birnbacher, Ulla; Schrotter, Peter

    2004-06-01

    The satisfaction of all communication needs from single households and business companies over a single access infrastructure is probably the most challenging topic in communications technology today. But even though the so-called "Last Mile Access Bottleneck" is well known since more than ten years and many distribution technologies have been tried out, the optimal solution has not yet been found and paying commercial access networks offering all service classes are still rare today. Conventional services like telephone, radio and TV, as well as new and emerging services like email, web browsing, online-gaming, video conferences, business data transfer or external data storage can all be transmitted over the well known and cost effective Ethernet networking protocol standard. Key requirements for the deployment technology driven by the different services are high data rates to the single customer, security, moderate deployment costs and good scalability to number and density of users, quick and flexible deployment without legal impediments and high availability, referring to the properties of optical and wireless communication. We demonstrate all elements of an Ethernet Access Network based on Free Space Optic distribution technology. Main physical parts are Central Office, Distribution Network and Customer Equipment. Transmission of different services, as well as configuration, service upgrades and remote control of the network are handled by networking features over one FSO connection. All parts of the network are proven, the latest commercially available technology. The set up is flexible and can be adapted to any more specific need if required.

  11. Accessibility of sulfhydryl residues induced by cytochalasin B binding and conformational dynamics in the human erythrocyte glucose transporter.

    PubMed

    Pinkofsky, H B; Jung, C Y

    1985-07-01

    Studies with intact cells have implicated essential sulfhydryl groups in the carrier-mediated glucose transport of human erythrocytes. In an attempt to identify and characterize such essential sulfhydryl residues we have studied the interaction of p-chloromercuribenzoate (PCMB) with a purified glucose transporter preparation (band 4.5) from human erythrocytes, in the presence and absence of its ligands, and the effects of this interaction on the binding of cytochalasin B (CB) to the transporter. At least 3 mol of PCMB reacted per mol of this preparation. A portion of the reaction was significantly enhanced in the presence of cytochalasin B. This enhancement was a saturable function of CB concentration, and was half-maximal at a CB concentration equal to the dissociation constant for the CB binding to the preparation. This CB-sensitive, PCMB reaction product comigrated with the band 4.5 on lithium dodecyl sulfate-polyacrylamide gel electrophoresis. An excess of D-glucose did not affect the PCMB reaction by itself in the absence of CB, but totally abolished the CB-induced enhancement of the PCMB reaction. PCMB inhibited the CB binding activity of the transporter preparation, and this inhibition was also enhanced in the presence of CB. These results suggest that CB binding perturbs the conformational dynamics of the glucose transporter resulting in an exposure of at least two sulfhydryl residues to PCMB reaction, and that some of these CB-sensitive sulfhydryl groups are essential for CB binding to the transporter.

  12. An Indoor Space Partition Method and its Fingerprint Positioning Optimization Considering Pedestrian Accessibility

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Shi, Yong; Zheng, Xingyu; Long, Yi

    2016-06-01

    Fingerprint positioning method is generally the first choice in indoor navigation system due to its high accuracy and low cost. The accuracy depends on partition density to the indoor space. The accuracy will be higher with higher grid resolution. But the high grid resolution leads to significantly increasing work of the fingerprint data collection, processing and maintenance. This also might decrease the performance, portability and robustness of the navigation system. Meanwhile, traditional fingerprint positioning method use equational grid to partition the indoor space. While used for pedestrian navigation, sometimes a person can be located at the area where he or she cannot access. This paper studied these two issues, proposed a new indoor space partition method considering pedestrian accessibility, which can increase the accuracy of pedestrian position, and decrease the volume of the fingerprint data. Based on this proposed partition method, an optimized algorithm for fingerprint position was also designed. A across linker structure was used for fingerprint point index and matching. Experiment based on the proposed method and algorithm showed that the workload of fingerprint collection and maintenance were effectively decreased, and poisoning efficiency and accuracy was effectively increased

  13. Ab initio materials design using conformational space annealing and its application to searching for direct band gap silicon crystals

    NASA Astrophysics Data System (ADS)

    Lee, In-Ho; Oh, Young Jun; Kim, Sunghyun; Lee, Jooyoung; Chang, K. J.

    2016-06-01

    Lately, the so-called inverse method of materials design has drawn much attention, where specific material properties are initially assigned and target materials are subsequently searched for. Although this method has been successful for some problems, the success of designing complex crystal structures containing many atoms is often limited by the efficiency of the search method utilized. Here we combine the global optimization method of conformational space annealing (CSA) with first-principles quantum calculations and report a new scheme named AMADEUS (Ab initio MAterials DEsign Using cSa). We demonstrate the utility of AMADEUS through the discovery of direct band gap Si crystals. The newly-designed direct gap Si allotropes show excellent optical properties and the spectroscopic limited maximum efficiencies comparable to those of best-known non-silicon photovoltaic materials. Our scheme not only provides a new perspective for the inverse problem of materials design but also may serve as a new tool for the computational design of a wide range of materials.

  14. Virtual Mission Operations of Remote Sensors With Rapid Access To and From Space

    NASA Technical Reports Server (NTRS)

    Ivancic, William D.; Stewart, Dave; Walke, Jon; Dikeman, Larry; Sage, Steven; Miller, Eric; Northam, James; Jackson, Chris; Taylor, John; Lynch, Scott; Heberle, Jay

    2010-01-01

    This paper describes network-centric operations, where a virtual mission operations center autonomously receives sensor triggers, and schedules space and ground assets using Internet-based technologies and service-oriented architectures. For proof-of-concept purposes, sensor triggers are received from the United States Geological Survey (USGS) to determine targets for space-based sensors. The Surrey Satellite Technology Limited (SSTL) Disaster Monitoring Constellation satellite, the United Kingdom Disaster Monitoring Constellation (UK-DMC), is used as the space-based sensor. The UK-DMC s availability is determined via machine-to-machine communications using SSTL s mission planning system. Access to/from the UK-DMC for tasking and sensor data is via SSTL s and Universal Space Network s (USN) ground assets. The availability and scheduling of USN s assets can also be performed autonomously via machine-to-machine communications. All communication, both on the ground and between ground and space, uses open Internet standards.

  15. Space environment data storage and access: lessons learned and recommendations for the future

    NASA Astrophysics Data System (ADS)

    Evans, Hugh; Heynderickx, Daniel

    2012-07-01

    With the ever increasing volume of space environment data available at present and planned for the near future, the demands on data storage and access methods are increasing as well. In addition, continued access to historical, archived data remains crucial. On the basis of many years of experience, the authors identify the following issues as important for continued and efficient handling of datasets now and in the future: The huge data volumes currently or very soon avaiable from a number of space missions will limi direct Internet download access to even relatively short epoch ranges of data. Therefore, data providers should establish or extend standardised data (post-) processing services so that only data query results should be downloaded. Although a single standardised data format will in all likelihood remain utopia, data providers should at least include extensive metadata with their data products, according to established standards and practices (e.g. ISTP, SPASE). Standardisation of (sets of) metadata greatly facilitates data mining and querying. The use of SQL database storage should be considered instead of, or in parallel with, classic storage of data files. The use of SQL does away with having to handle file parsing and processing, while at the same time standard access protocols can be used to (remotely) connect to such data repositories. Many data holdings are still lacking in extensive descriptions of data provenance (e.g. instrument description), content and format. Unfortunately, detailed data information is usually rejected by scientific and technical journals. Re-processing of historical archived datasets into modern formats, making them easily available and usable, is urgently required, as knowledge is being lost. A global data directory has still not been achieved; policy makers should enforce stricter rules for "broadcasting" dataset information.

  16. ESPAS: the European e-science platform to access near-Earth space data (Invited)

    NASA Astrophysics Data System (ADS)

    Belehaki, A.; Hapgood, M. A.; Ritschel, B.; Manola, N.

    2013-12-01

    The aim of ESPAS platform is to integrate heterogeneous data from the earth's thermosphere, ionosphere, plasmasphere and magnetosphere. ESPAS supports the systematic exploration of multipoint measurements from the near-Earth space through homogenised access to multi-instrument data. It provides access to more than 40 datasets: Cluster, EISCAT, GIRO, DIAS, SWACI, CHAMP, SuperDARN, FPI, magnetometers INGV, SGO, DTU, IMAGE, TGO, IMAGE/RPI, ACE, SOHO, PROBA2, NOAA/POES, etc. The concept of extensibility to new data sets is an important element in the ESPAS architecture. Within the first year of the project, the main components of the system have been developed, namely, the data model, the XML schemas for metadata exchange format, the ontology, the wrapper installed at the data nodes so that the main platform harvest the metadata, the main platform built on the D-NET framework and the GUI with its designed workflows. The first working prototype supports the search for datasets among a selected number of databases (i.e., EDAM, DIAS, Cluster, SWACI data). The next immediate step would be the implementation of search for characteristics within the datasets. For the second release we are planning to deploy tools for conjunctions between ground-space and space-space and for coincidences. For the final phase of the project the ESPAS infrastructure will be extensively tested through the application of several use cases, designed to serve the needs of the wide interdisciplinary users and producers communities, such as the ionospheric, thermospheric, magnetospheric, space weather and space climate communities, the geophysics community, the space communications engineering, HF users, satellite operators, navigation and surveillance systems, and space agencies. The final ESPAS platform is expected to be delivered in 2015. The abstract is submitted on behalf of the ESPAS-FP7EU team (http://www.espas-fp7.eu): Mike Hapgood, Anna Belehaki, Spiros Ventouras, Natalia Manola, Antonis

  17. 41 CFR 102-79.65 - May Executive agencies outlease space on major public access levels, courtyards and rooftops of...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... outlease space on major public access levels, courtyards and rooftops of public buildings? 102-79.65... levels, courtyards and rooftops of public buildings? Yes. Authority to execute such outleases may be... major public access levels, courtyards and rooftops of any public building with persons, firms,...

  18. Accessibility and use of urban green spaces, and cardiovascular health: findings from a Kaunas cohort study

    PubMed Central

    2014-01-01

    Background The aims of this study were to explore associations of the distance and use of urban green spaces with the prevalence of cardiovascular diseases (CVD) and its risk factors, and to evaluate the impact of the accessibility and use of green spaces on the incidence of CVD among the population of Kaunas city (Lithuania). Methods We present the results from a Kaunas cohort study on the access to and use of green spaces, the association with cardiovascular risk factors and other health-related variables, and the risk of cardiovascular mortality and morbidity. A random sample of 5,112 individuals aged 45-72 years was screened in 2006-2008. During the mean 4.41 years follow-up, there were 83 deaths from CVD and 364 non-fatal cases of CVD among persons free from CHD and stroke at the baseline survey. Multivariate Cox proportional hazards regression models were used for data analysis. Results We found that the distance from people’s residence to green spaces was not related to the prevalence of health-related variables. However, the prevalence of cardiovascular risk factors and the prevalence of diabetes mellitus were significantly lower among park users than among non-users. During the follow up, an increased risk of non-fatal and fatal CVD combined was observed for those who lived ≥629.61 m from green spaces (3rd tertile of distance to green space) (hazard ratio (HR) = 1.36), and the risk for non-fatal CVD–for those who lived ≥347.81 m (2nd and 3rd tertile) and were not park users (HR = 1.66) as compared to men and women who lived 347.8 m or less (1st tertile) from green space. Men living further away from parks (3rd tertile) had a higher risk of non-fatal and fatal CVD combined, compared to those living nearby (1st tertile) (HR = 1.51). Compared to park users living nearby (1st tertile), a statistically significantly increased risk of non-fatal CVD was observed for women who were not park users and living farther away from parks (2nd and 3rd tertile) (HR

  19. A rapid prototyping/artificial intelligence approach to space station-era information management and access

    NASA Technical Reports Server (NTRS)

    Carnahan, Richard S., Jr.; Corey, Stephen M.; Snow, John B.

    1989-01-01

    Applications of rapid prototyping and Artificial Intelligence techniques to problems associated with Space Station-era information management systems are described. In particular, the work is centered on issues related to: (1) intelligent man-machine interfaces applied to scientific data user support, and (2) the requirement that intelligent information management systems (IIMS) be able to efficiently process metadata updates concerning types of data handled. The advanced IIMS represents functional capabilities driven almost entirely by the needs of potential users. Space Station-era scientific data projected to be generated is likely to be significantly greater than data currently processed and analyzed. Information about scientific data must be presented clearly, concisely, and with support features to allow users at all levels of expertise efficient and cost-effective data access. Additionally, mechanisms for allowing more efficient IIMS metadata update processes must be addressed. The work reported covers the following IIMS design aspects: IIMS data and metadata modeling, including the automatic updating of IIMS-contained metadata, IIMS user-system interface considerations, including significant problems associated with remote access, user profiles, and on-line tutorial capabilities, and development of an IIMS query and browse facility, including the capability to deal with spatial information. A working prototype has been developed and is being enhanced.

  20. Analysis of Potential Alternatives to Reduce NASA's Cost of Human Access to Space

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The purpose of this report is to analyze NASA's potential options for significantly reducing the cost of human access to space. The opinions expressed in this report are based on Hawthorne, Krauss & Associates' ("HKA") interaction with NASA and several of its key contractors over the past nine months. This report is not intended to be an exhaustive quantitative analysis of the various options available to NASA. Instead, its purpose is to outline key decision-related issues that the agency should consider prior to making a decision as to which option to pursue. This report attempts to bring a private-sector perspective to bear on the issue of reducing the cost of human access to space. HKA believes that the key to the NASA's success in reducing those costs over the long-term is the involvement of the private-sector incentives and disciplines--which is achieved only through the assumption of risk by the private sector, not through a traditional contractor relationship--is essential to achieve significant long-term cost reductions.

  1. Virtual Observatories for Space Physics Observations and Simulations: New Routes to Efficient Access and Visualization

    NASA Technical Reports Server (NTRS)

    Roberts, Aaron

    2005-01-01

    New tools for data access and visualization promise to make the analysis of space plasma data both more efficient and more powerful, especially for answering questions about the global structure and dynamics of the Sun-Earth system. We will show how new existing tools (particularly the Virtual Space Physics Observatory-VSPO-and the Visual System for Browsing, Analysis and Retrieval of Data-ViSBARD; look for the acronyms in Google) already provide rapid access to such information as spacecraft orbits, browse plots, and detailed data, as well as visualizations that can quickly unite our view of multispacecraft observations. We will show movies illustrating multispacecraft observations of the solar wind and magnetosphere during a magnetic storm, and of simulations of 3 0-spacecraft observations derived from MHD simulations of the magnetosphere sampled along likely trajectories of the spacecraft for the MagCon mission. An important issue remaining to be solved is how best to integrate simulation data and services into the Virtual Observatory environment, and this talk will hopefully stimulate further discussion along these lines.

  2. ACCESS - A Science and Engineering Assessment of Space Coronagraph Concepts for the Direct Imaging and Spectroscopy of Exoplanetary Systems

    NASA Technical Reports Server (NTRS)

    Trauger, John

    2008-01-01

    Topics include and overview, science objectives, study objectives, coronagraph types, metrics, ACCESS observatory, laboratory validations, and summary. Individual slides examine ACCESS engineering approach, ACCESS gamut of coronagraph types, coronagraph metrics, ACCESS Discovery Space, coronagraph optical layout, wavefront control on the "level playing field", deformable mirror development for HCIT, laboratory testbed demonstrations, high contract imaging with the HCIT, laboratory coronagraph contrast and stability, model validation and performance predictions, HCIT coronagraph optical layout, Lyot coronagraph on the HCIT, pupil mapping (PIAA), shaped pupils, and vortex phase mask experiments on the HCIT.

  3. Accessing Solar Irradiance Data via LISIRD, the Laboratory for Atmospheric and Space Physics Interactive Solar Irradiance Datacenter

    NASA Astrophysics Data System (ADS)

    Pankratz, C. K.; Wilson, A.; Snow, M. A.; Lindholm, D. M.; Woods, T. N.; Traver, T.; Woodraska, D.

    2015-12-01

    The LASP Interactive Solar Irradiance Datacenter, LISIRD, http://lasp.colorado.edu/lisird, allows the science community and the public to explore and access solar irradiance and related data sets using convenient, interactive or scriptable, standards-based interfaces. LISIRD's interactive plotting allows users to investigate and download irradiance data sets from a variety of sources, including space missions, ground observatories, and modeling efforts. LISIRD's programmatic interfaces allow software-level data retrievals and facilitate automation. This presentation will describe the current state of LISIRD, provide details of the data sets it serves, outline data access methods, identify key technologies in-use, and address other related aspects of serving spectral and other time series data. We continue to improve LISIRD by integrating new data sets, and also by advancing its data management and presentation capabilities to meet evolving best practices and community needs. LISIRD is hosted and operated by the Laboratory for Atmospheric and Space Physics, LASP, which has been a leader in Atmospheric and Heliophysics science for over 60 years. LASP makes a variety of space-based measurements of solar irradiance, which provide crucial input for research and modeling in solar-terrestrial interactions, space physics, planetary, atmospheric, and climate sciences. These data sets consist of fundamental measurements, composite data sets, solar indices, space weather products, and models. Current data sets available through LISIRD originate from the SORCE, SDO (EVE), UARS (SOLSTICE), TIMED (SEE), and SME space missions, as well as several other space and ground-based projects. LISIRD leverages several technologies to provide flexible and standards-based access to the data holdings available through LISIRD. This includes internet-accessible interfaces that permit data access in a variety of formats, data subsetting, as well as program-level access from data analysis

  4. Creating Assemblies in Media Space: Recent Developments in Enhancing Access to Workspaces

    NASA Astrophysics Data System (ADS)

    Luff, Paul; Kuzuoka, Hideaki; Heath, Christian; Yamazaki, Keiichi; Yamashita, Jun

    In this chapter, we discuss a programme of social and technical research that we have undertaken over the last few years concerned with the design, assessment and development of systems to support real-time, distributed work; work that relies upon a participants' ability to access a range of tangible and digital resources. The programme of work has been informed by findings from a range of studies of work and collaboration in environments that include architectural practices, control centres, surgeries, hospitals, news rooms, and the like. These studies have a framework of considerations, criteria, and insights into the organization of everyday work and interaction that have enabled us to identify some of the limitations of con¬ventional media spaces, including systems which we have helped develop, and to pose a set of requirements and challenges, which we believe are fundamental to the creation of a media space that could support the flexible and contingent demands of seemingly simple forms of collaborative work. These studies, coupled with the development and assessment of a series of experimental systems, have enabled us to identify three key issues that we believe have to be addressed and resolved (in one way or another) if media space research is going to achieve its early potential.

  5. Sounding Rockets within Swedish National Balloon and Rocket Programme- Providing Access to Space from Esrange

    NASA Astrophysics Data System (ADS)

    Sjolander, K.; Karlsson, T.; Lockowandt, C.

    2015-09-01

    Initiated in 2012 by the Swedish National Space Board (SNSB), a new programme dedicated for Swedish scientists to gain access to space using balloons and sounding rockets was started. This programme promotes the possibility to ensure continuity in both the science and the technology used. The sounding rocket part of this national programme started with three possible missions. SPIDER (Small Payloads for Investigation of Disturbances in Electrojet by Rockets) from the Space and Plasma physics department of KTH, 0-STATES (Oxygen Species and Thermospheric Airglow in The Earth's Sky) from the Department of Meteorology Stockholm University (MISU) and LEEWAVES (Local Excitation and Effects of Waves on Atmospheric VErtical Structure) that is collaboration between KTH and MISU. These three missions were planned for launches in 2015 and 2016. SSc has been contracted on a launch ticket basis to provide the launch and service to the scientific instrumentation. This paper presents the SPIDER, 0-STATES and LEEWAVES missions focussing on a mission related technical solutions perspective.

  6. Conformal Carroll groups

    NASA Astrophysics Data System (ADS)

    Duval, C.; Gibbons, G. W.; Horvathy, P. A.

    2014-08-01

    Conformal extensions of Lévy-Leblond's Carroll group, based on geometric properties analogous to those of Newton-Cartan space-time are proposed. The extensions are labeled by an integer k. This framework includes and extends our recent study of the Bondi-Metzner-Sachs (BMS) and Newman-Unti (NU) groups. The relation to conformal Galilei groups is clarified. Conformal Carroll symmetry is illustrated by ‘Carrollian photons’. Motion both in the Newton-Cartan and Carroll spaces may be related to that of strings in the Bargmann space.

  7. Assay for transposase-accessible chromatin and circularized chromosome conformation capture, two methods to explore the regulatory landscapes of genes in zebrafish.

    PubMed

    Fernández-Miñán, A; Bessa, J; Tena, J J; Gómez-Skarmeta, J L

    2016-01-01

    Accurate transcriptional control of genes is fundamental for the correct functioning of organs and developmental processes. This control depends on the interplay between the promoter of genes and other noncoding sequences, whose interaction is mediated by 3D chromatin arrangements. Thus, the detailed description of transcriptional regulatory landscapes is essential to understand the mechanisms of transcriptional regulation. However, to achieve that, two important challenges have to be faced: (1) the identification of the noncoding sequences that contribute to gene transcription and (2) the association of these sequences to the respective genes they control. In this chapter, we describe two protocols that allow overcoming these important challenges: the assay for transposase-accessible chromatin using sequencing (ATAC-seq) and circularized chromosome conformation capture (4C-seq). ATAC-seq is a very efficient technique that, using a very low number of cells as starting material, allows the identification of active chromatin regions genome wide, whereas 4C-seq detects the subset of sequences that interact specifically with the promoter of a given gene. When combined, both techniques provide a comprehensive snapshot of the regulatory landscapes of developmental genes. The protocols we present here have been optimized for teleost fish samples, zebrafish and medaka, allowing the in-depth study of transcriptional regulation in these two emerging animal models. Given the amenability and easy genetic manipulation of these two experimental systems, we anticipate that they will be important in revealing general principles of the vertebrate regulatory genome.

  8. Based on asynchronous communication protocol of geographic space information service access mechanism research

    NASA Astrophysics Data System (ADS)

    Chen, G.; Zhao, J.; Gu, M.; Li, D.

    2014-04-01

    At present, the traditional way of accessing to classified network in geographic spatial information services is using network gatekeeper and firewall etc. to ensure public and classified network communications links. However, the physical isolation between classified network and public network is crossed, which is bound to cause classified network potential security hazard. In Yunnan province space Land dynamic monitoring integration project, it proposed the point to point text message communication protocol and asynchronous transmission mechanism. Using geo-spatial information encryption processing and data compression processing method, it reduced the risk of data sensitivity and monitored, namely to ensure data security, which realized geographic spatial information services data communication effectively between classified network and public network in the rigid field conditions.

  9. The University of Arizona Nanosat Program: Making Space accessible to scientific and commercial packages.

    NASA Astrophysics Data System (ADS)

    Fink, U.; Fevig, R. A.

    2003-05-01

    For the last couple of years we have been engaged in building nanosatellites within a student-mentor framework. The satellites are 10x10x10cm cubes, have a maximum mass of 1 kg, and power of a few watts. The standardized "cube-sat" form factor was suggested by Bob Twiggs of Stanford University so that a common launch platform could be utilized and more Universities could participate. We have now built four "cube-sats': a launchable Engineering model, Rincon 1 & 2, (funded by Rincon corporation), and Alcatel funded by Alcatel Espace. The costs for the four satellites are \\250,000. Launch costs using a Russian SS-18 are typically \\10,000 per kg. The payload for Rincon 1 & 2 is a sophisticated telecommunications board using only 10 mw of transmitting power. The Alcatel payload consists of three communications IC's whose radiation exposure and annealing properties will be studied over a period of years. Future nanosatellites will have considerable value in providing low cost access to space for experiments in nanotechnology, space electronics, micropropulsion, radiation experiments, astrobionics and climate change studies. For the latter area we are considering experiments to monitor the solar constant, the solar UV spectrum, the chromospheric activity through the Mg II index, the Earth's Albedo, etc. For this purpose we are developing a slightly larger satellite, 20x20x20cm and 10 kg. We have built a C-MOS camera with a 1 ms exposure time for attitude determination, and we are working with Honeywell Industries to develop micro-reaction wheels for attitude control. We are also working on micro-propulsion units with the Air Force and several aerospace companies. Preliminary calculations show that we can develop delta-V's of 5km/s which will allow us to visit 5% (about 100) of the NEA population or possibly some comets. We firmly believe a vigorous nanosatellite program will allow useful space experiments for costs of millions of Dollars instead of the present tens of

  10. An Alternative and Validated Injection Method for Accessing the Subretinal Space via a Transcleral Posterior Approach.

    PubMed

    Parikh, Sachin; Le, Andrew; Davenport, Julian; Gorin, Michael B; Nusinowitz, Steven; Matynia, Anna

    2016-12-07

    Subretinal injections have been successfully used in both humans and rodents to deliver therapeutic interventions of proteins, viral agents, and cells to the interphotoreceptor/subretinal compartment that has direct exposure to photoreceptors and the retinal pigment epithelium (RPE). Subretinal injections of plasminogen as well as recent preclinical and clinical trials have demonstrated safety and/or efficacy of delivering viral vectors and stem cells to individuals with advanced retinal disease. Mouse models of retinal disease, particularly hereditary retinal dystrophies, are essential for testing these therapies. The most common injection procedure in rodents is to use small transcorneal or transcleral incisions with an anterior approach to the retina. With this approach, the injection needle penetrates the neurosensory retina disrupting the underlying RPE and on insertion can easily nick the lens, causing lens opacification and impairment of noninvasive imaging. Accessing the subretinal space via a transcleral, posterior approach avoids these problems: the needle crosses the sclera approximately 0.5 mm from the optic nerve, without retinal penetration and avoids disrupting the vitreous. Collateral damage is limited to that associated with the focal sclerotomy and the effects of a transient, serous retinal detachment. The simplicity of the method minimizes ocular injury, ensures rapid retinal reattachment and recovery, and has a low failure rate. The minimal damage to the retina and RPE allows for clear assessment of the efficacy and direct effects of the therapeutic agents themselves. This manuscript describes a novel subretinal injection technique that can be used to target viral vectors, pharmacological agents, stem cells or induced pluripotent stem (iPS) cells to the subretinal space in mice with high efficacy, minimal damage, and fast recovery.

  11. A Science Information Infrastructure for Access to Earth and Space Science Data through the Nation's Science Museums

    NASA Technical Reports Server (NTRS)

    Murray, S.

    1999-01-01

    In this project, we worked with the University of California at Berkeley/Center for Extreme Ultraviolet Astrophysics and five science museums (the National Air and Space Museum, the Science Museum of Virginia, the Lawrence Hall of Science, the Exploratorium., and the New York Hall of Science) to formulate plans for computer-based laboratories located at these museums. These Science Learning Laboratories would be networked and provided with real Earth and space science observations, as well as appropriate lesson plans, that would allow the general public to directly access and manipulate the actual remote sensing data, much as a scientist would.

  12. Interplanetary space science data base and access/display tool on the NSSDC heliospheric CD-ROM

    NASA Technical Reports Server (NTRS)

    Papitashvili, N. E.; King, J. H.

    1995-01-01

    The National Space Science Data Center (NSSDC) has accumulated a rich archive of heliospheric, magnetospheric, and ionospheric data, as well as data from most other NASA-involved science disciplines. To facilitate access to and use of these data, NSSDC has begun to put selected data onto CD-ROM's. This paper describes one such CD-ROM, and the access and display software developed at NSSDC to support its use. The data on the CD-ROM consist primarily of hourly solar wind magnetic field and plasma data from many near-Earth spacecraft (OMNI) and deep space spacecraft (Voyagers, Pioneers, Helios, Pioneer Venus Orbiter). In addition, 5-minute resolution IMP-8 and ISEE-3 magnetic field and plasma data are also included. Data are stored in both ASCII and CDF formats.

  13. Combined effects of f(R) gravity and conformally invariant Maxwell field on the extended phase space thermodynamics of higher-dimensional black holes

    NASA Astrophysics Data System (ADS)

    Mo, Jie-Xiong; Li, Gu-Qiang; Xu, Xiao-Bao

    2016-10-01

    In this paper, we investigate the thermodynamics of higher-dimensional f( R) black holes in the extended phase space. Both the analytic expressions and the numerical results for the possible critical physical quantities are obtained. It is proved that meaningful critical specific volume only exists when p is odd. This unique phenomenon may be attributed to the combined effect of f( R) gravity and conformally invariant Maxwell field. It is also shown that the ratio P_cv_c/T_c differs from that of higher-dimensional charged AdS black holes in Einstein gravity. However, the ratio for four-dimensional f( R) black holes is the same as that of four-dimensional RN-AdS black holes, implying that f( R) gravity does not influence the ratio. So the ratio may be related to conformally invariant Maxwell field. To probe the phase transition, we derive the explicit expression of the Gibbs free energy with its graph plotted. A phase transition analogous to the van der Waals liquid-gas system takes place between the small black hole and the large black hole. Classical swallow tail behavior, characteristic of first-order phase transitions, can also be observed in the Gibbs free energy graph. Critical exponents are also calculated. It is shown that these exponents are exactly the same as those of other AdS black holes, implying that neither f( R) gravity nor conformally invariant Maxwell field influence the critical exponents. Since the investigated black hole solution depends on the form of the function f( R), we discuss in detail how our results put constraint on the form of the function f( R) and we also present a simple example.

  14. Group Cohesiveness, Deviation, Stress, and Conformity

    DTIC Science & Technology

    1993-08-11

    assessed pre- and post- conformity pressure (see Appendix VIII). Components of group influences , Offer of Reward for Conformity (ORC), and Threat of...Cohesiveness Pressures to Uniformity Studies . . . . Evidence Supporting a Group Cohesiveness- Conformity Relationship . . . . . . Evidence Supporting a...Response and Conformity Pressure . . . . Stress and ORC and TPN . . . . . . . . TPN and Space Crews . . . . . . . . . . Summary of Group

  15. Vacuum Averages of the Energy-Momentum Tensor of a Scalar Field in Homogeneous Spaces with a Conformal Metric

    NASA Astrophysics Data System (ADS)

    Breev, A. I.; Kozlov, A. V.

    2016-01-01

    Within the framework of the method of orbits, expressions have been obtained for the vacuum averages of the energy-momentum tensor of a scalar field with an arbitrary coupling constant in a spacetime with a nonstationary metric of Robertson-Walker type, where space is a homogeneous Riemannian manifold. It is shown that the vacuum averages of the energy-momentum tensor are determined by the complete set of solutions of the reduced equation with a smaller number of independent variables and with algebraic characteristics of homogeneous space.

  16. Conformation-determined through-bond versus through-space electronic communication in mixed-valence systems with a cross-conjugated urea bridge.

    PubMed

    Gong, Zhong-Liang; Zhong, Yu-Wu; Yao, Jiannian

    2015-01-19

    Bis-triarylamine 2 and cyclometalated diruthenium 6(PF6)2 with a linear trans,trans-urea bridge have been prepared, together with the bis-triarylamine 3 and cyclometalated diruthenium 8(PF6)2 with a folded cis,cis-N,N-dimethylurea bridge. The linear or folded conformations of these molecules are supported by single-crystal X-ray structures of 2, 3, and other related compounds. These compounds display two consecutive anodic redox waves (N(·+/0) or Ru(III/II) processes) with a potential separation of 110-170 mV. This suggests that an efficient electronic coupling is present between two redox termini through the cross-conjugated urea bridge. The degree of electronic coupling has been investigated by using spectroelectrochemical measurements. Distinct intervalence charge-transfer (IVCT) transitions have been observed for mixed-valent (MV) compounds with a linear conformation. The IVCT transitions can also be identified for the folded MV compounds, albeit with a much weaker intensity. DFT results support that the electronic communication occurs by a through-bond and through-space pathway for the linear and folded compounds, respectively. The IVCT transitions of the MV compounds have been reproduced by TDDFT calculations. For the purpose of comparison, a bistriarylamine and a diruthenium complex with an imidazolidin-2-one bridge and a urea-containing mono-triarylamine and monoruthenium complex have been synthesized and studied.

  17. Transportation Conformity

    EPA Pesticide Factsheets

    This section provides information on: current laws, regulations and guidance, policy and technical guidance, project-level conformity, general information, contacts and training, adequacy review of SIP submissions

  18. US access to space: Launch vehicle choices for 1990 to 2010

    NASA Astrophysics Data System (ADS)

    Pace, Scott N.

    1989-12-01

    Combinations of U.S. launch vehicles capable of meeting a range of government space traffic needs between 1990 and 2010 are evaluated. The purpose of this evaluation is to clarify alternatives available to the United States in pursuing potential national goals and to increase understanding of the implications of those alternatives. Wartime requirements for space launches were not included. Four levels of U.S. space traffic demand for 1990 to 2010 were defined. The first level was budget constrained to limit new program starts. The second level was a continuation of current space traffic plans, including the Space Station program. The third level assumed an expansion of civil space efforts such as a return to the Moon. The fourth level assumed expanded military space efforts such as the development of strategic defenses. Differing combination of existing and proposed launch vehicles were defined to fulfill each demand level. The costs and uncertainties (e.g., payload losses) associated with each launch vehicle combination were estimated. The interrelations of payload costs, launch vehicle costs, and system reliabilities are discussed in the appendices. The space transportation planning process, current issues, and political factors affecting analysis are reviewed. Senior space transportation planners and decision-makers were interviewed on differing institutional criteria for evaluating launch vehicle mixes. Evaluation criteria were defined to assess the launch vehicle mixes for each demand level and for the case of uncertain demand. Recommendations on preferred U.S. actions in space transportation are made based both on analyses and interview results.

  19. Intensity distribution based space and time division multiple access technique for hybrid-LOS indoor optical wireless communication

    NASA Astrophysics Data System (ADS)

    Miyamoto, Shinichi; Kawamoto, Kenji; Sampei, Seiichi

    2010-02-01

    This paper proposes a space division and time division multiple access (SD/TDMA) technique based on intensity distributions for hybrid line-of-sight (hybrid-LOS) indoor optical wireless communication system. At first, a novel signal discrimination scheme for the spatially multiplexed optical signals is proposed and it is applied to a space division multiple access (SDMA) in hybrid-LOS system. In the proposed scheme, multiple terminals simultaneously transmit their optical signals to access point (AP) using on-off-keying (OOK) modulation, and the spatially multiplexed optical signals are received by a photodetectors array (PD-array), where multiple PDs are disposed to observe the spatial intensity distribution of optical signals. Because the terminals transmit their data using OOK modulation, the spatial intensity distribution observed by the AP equipped with PD-array is subject to the data transmitted from individual terminals, and the AP can identify the terminals transmitting the optical signal by determining the transmitted intensity distribution. Of course, the transmitted intensity distributions are not orthogonal signal and the discriminability of transmitted intensity distributions is much related to the differences of intensity distributions. This implies that the number of terminals that can simultaneously access to the AP will be limited and it is determined by the differences of the candidate intensity distributions. In order to enhance the discriminability of the transmitted intensity distributions, the proposed signal discrimination scheme is further applied to the SD/TDMA. In the SD/TDMA, the discriminability required to enable SDMA is ensured by introducing a scheduling algorithm in which terminals with higher discriminatory of transmitted intensity distributions are allocated to the same time slot. Numerical results show that SD/TDMA using proposed signal discrimination scheme increases the throughput and the number of terminals that can access to

  20. Probing Receptor Specificity by Sampling the Conformational Space of the Insulin-like Growth Factor II C-domain*

    PubMed Central

    Hexnerová, Rozálie; Křížková, Květoslava; Fábry, Milan; Sieglová, Irena; Kedrová, Kateřina; Collinsová, Michaela; Ullrichová, Pavlína; Srb, Pavel; Williams, Christopher; Crump, Matthew P.; Tošner, Zdeněk; Jiráček, Jiří; Veverka, Václav; Žáková, Lenka

    2016-01-01

    Insulin and insulin-like growth factors I and II are closely related protein hormones. Their distinct evolution has resulted in different yet overlapping biological functions with insulin becoming a key regulator of metabolism, whereas insulin-like growth factors (IGF)-I/II are major growth factors. Insulin and IGFs cross-bind with different affinities to closely related insulin receptor isoforms A and B (IR-A and IR-B) and insulin-like growth factor type I receptor (IGF-1R). Identification of structural determinants in IGFs and insulin that trigger their specific signaling pathways is of increasing importance in designing receptor-specific analogs with potential therapeutic applications. Here, we developed a straightforward protocol for production of recombinant IGF-II and prepared six IGF-II analogs with IGF-I-like mutations. All modified molecules exhibit significantly reduced affinity toward IR-A, particularly the analogs with a Pro-Gln insertion in the C-domain. Moreover, one of the analogs has enhanced binding affinity for IGF-1R due to a synergistic effect of the Pro-Gln insertion and S29N point mutation. Consequently, this analog has almost a 10-fold higher IGF-1R/IR-A binding specificity in comparison with native IGF-II. The established IGF-II purification protocol allowed for cost-effective isotope labeling required for a detailed NMR structural characterization of IGF-II analogs that revealed a link between the altered binding behavior of selected analogs and conformational rearrangement of their C-domains. PMID:27510031

  1. Killing Initial Data on spacelike conformal boundaries

    NASA Astrophysics Data System (ADS)

    Paetz, Tim-Torben

    2016-08-01

    We analyze Killing Initial Data on Cauchy surfaces in conformally rescaled vacuum space-times satisfying Friedrich's conformal field equations. As an application, we derive the KID equations on a spacelike ℐ-.

  2. Accessing space: A catalogue of process, equipment and resources for commercial users, 1990

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A catalogue is presented which is intended for commercial developers who are considering, or who have in progress, a project involving the microgravity environment of space or remote sensing of the Earth. An orientation is given to commercial space activities along with a current inventory of equipment, apparatus, carriers, vehicles, resources, and services available from NASA, other government agencies and U.S. industry. The information describes the array of resources that commercial users should consider when planning ground or space based developments. Many items listed have flown in space or been tested in labs and aboard aircraft and can be reused, revitalized, or adapted to suit specific requirements. New commercial ventures are encouraged to exploit existing inventory and expertise to the greatest extent possible.

  3. Conformal Visualization for Partially-Immersive Platforms

    PubMed Central

    Petkov, Kaloian; Papadopoulos, Charilaos; Zhang, Min; Kaufman, Arie E.; Gu, Xianfeng

    2010-01-01

    Current immersive VR systems such as the CAVE provide an effective platform for the immersive exploration of large 3D data. A major limitation is that in most cases at least one display surface is missing due to space, access or cost constraints. This partially-immersive visualization results in a substantial loss of visual information that may be acceptable for some applications, however it becomes a major obstacle for critical tasks, such as the analysis of medical data. We propose a conformal deformation rendering pipeline for the visualization of datasets on partially-immersive platforms. The angle-preserving conformal mapping approach is used to map the 360°3D view volume to arbitrary display configurations. It has the desirable property of preserving shapes under distortion, which is important for identifying features, especially in medical data. The conformal mapping is used for rasterization, realtime raytracing and volume rendering of the datasets. Since the technique is applied during the rendering, we can construct stereoscopic images from the data, which is usually not true for image-based distortion approaches. We demonstrate the stereo conformal mapping rendering pipeline in the partially-immersive 5-wall Immersive Cabin (IC) for virtual colonoscopy and architectural review. PMID:26279083

  4. Small Satellites for Atmospheric and near earth Space sciences - the Indian perspectives of a low cost access to Space

    NASA Astrophysics Data System (ADS)

    Sridharan, R.

    Small satellites of 100-400 kg class are expected to play bigger roles in the years to come. With the advancement of technology in terms of miniaturization and also reliability, it has become possible to configure small satellites which otherwise would have demanded larger platforms, both in terms of weight and power. The atmospheric and near Earth space processes are truly multi-dimensional and are extremely complex with large temporal and spatial variability and also respond closely to the processes in the Sun. As a consequence, no single satellite mission would be able to provide the complete information thus warranting multiple missions. With the successful demonstration of multiple satellites launching capability, the spare capacity of the launch vehicles could be effectively and judiciously used for launching dedicated small scientific satellites as co passengers with negligible cost factor. This is viewed as an opening up of an otherwise difficult opportunity involving dedicated launches. With the prospect of multiple satellites for science missions becoming a reality the overall mission with an active life of 2-3 years could be realized with judicious choice of components. This is expected to bring in a larger user community in the country. The first step in this direction is the configuration of a modular micro and small satellite bus. The upcoming missions of TWSAT (Third world satellite), Youth Sat (active participation of the student community), SARAL (Satellite for ARGOs and Altimetry), SENSE/E and SENSE/P (Satellite for Earth's Near Space environment), ISTAG (Indian Satellite for Aerosols and Gases), are utilizing the above concepts. ISRO has also come out with AO's for Astronomy and Astrophysics payloads, as most of the stringent requirements of various experiments could be met with the small satellite platforms themselves. A brief outline of the upcoming and proposed activities would be presented and discussed in the talk.

  5. General Conformity

    EPA Pesticide Factsheets

    The General Conformity requirements ensure that the actions taken by federal agencies in nonattainment and maintenance areas do not interfere with a state’s plans to meet national standards for air quality.

  6. Conformal Infinity

    NASA Astrophysics Data System (ADS)

    Frauendiener, Jörg

    2004-12-01

    The notion of conformal infinity has a long history within the research in Einstein's theory of gravity. Today, "conformal infinity" is related to almost all other branches of research in general relativity, from quantisation procedures to abstract mathematical issues to numerical applications. This review article attempts to show how this concept gradually and inevitably evolved from physical issues, namely the need to understand gravitational radiation and isolated systems within the theory of gravitation, and how it lends itself very naturally to the solution of radiation problems in numerical relativity. The fundamental concept of null-infinity is introduced. Friedrich's regular conformal field equations are presented and various initial value problems for them are discussed. Finally, it is shown that the conformal field equations provide a very powerful method within numerical relativity to study global problems such as gravitational wave propagation and detection.

  7. Electronically reconfigurable and mechanically conformal apertures using low-voltage MEMS and flexible membranes for space-based radar applications

    NASA Astrophysics Data System (ADS)

    Bernhard, Jennifer T.; Chen, Nan-Wei; Clark, Randall; Feng, Milton; Liu, Chang; Mayes, Paul; Michielssen, Eric; Wang, Roy R.; Chorosinski, Leonard G.

    2001-08-01

    The University of Illinois and Northrop Grumman Corporation have teamed to integrate a wide band reconfigurable aperture array with associated wide band T/R functions on a flexible and foldable/rollable substrate for space based radar applications. Advanced MEMS and packaging techniques are used to make the antenna array lightweight, reliable, and reproducible. Soft flexible substrates make the antenna foldable/rollable with the associated electronics below the ground plane of the antenna elements. The individually reconfigurable antenna element uses MEMS switches to select between two broad frequency bands of operation. These MEMS switches have low actuation voltages and stress-free operation, improving the array's reliability. The reconfigurable antenna element is based on a low-profile radiator that provides greatly increased instantaneous bandwidth over microstrip patch antennas currently in place for phased array applications. Voltage-controlled MEMS switches are utilized to switch between stacked layers of elements that operate in the S- and X-bands. In each band, the antenna elements provide at least 25% instantaneous bandwidth. The challenges presented by the flexible substrate and the array design as well as experimental and simulated results for the antenna elements and switches are discussed.

  8. Maglev Launch: Ultra-low Cost, Ultra-high Volume Access to Space for Cargo and Humans

    NASA Astrophysics Data System (ADS)

    Powell, James; Maise, George; Rather, John

    2010-01-01

    Despite decades of efforts to reduce rocket launch costs, improvements are marginal. Launch cost to LEO for cargo is ~$10,000 per kg of payload, and to higher orbit and beyond much greater. Human access to the ISS costs $20 million for a single passenger. Unless launch costs are greatly reduced, large scale commercial use and human exploration of the solar system will not occur. A new approach for ultra low cost access to space-Maglev Launch-magnetically accelerates levitated spacecraft to orbital speeds, 8 km/sec or more, in evacuated tunnels on the surface, using Maglev technology like that operating in Japan for high speed passenger transport. The cost of electric energy to reach orbital speed is less than $1 per kilogram of payload. Two Maglev launch systems are described, the Gen-1System for unmanned cargo craft to orbit and Gen-2, for large-scale access of human to space. Magnetically levitated and propelled Gen-1 cargo craft accelerate in a 100 kilometer long evacuated tunnel, entering the atmosphere at the tunnel exit, which is located in high altitude terrain (~5000 meters) through an electrically powered ``MHD Window'' that prevents outside air from flowing into the tunnel. The Gen-1 cargo craft then coasts upwards to space where a small rocket burn, ~0.5 km/sec establishes, the final orbit. The Gen-1 reference design launches a 40 ton, 2 meter diameter spacecraft with 35 tons of payload. At 12 launches per day, a single Gen-1 facility could launch 150,000 tons annually. Using present costs for tunneling, superconductors, cryogenic equipment, materials, etc., the projected construction cost for the Gen-1 facility is 20 billion dollars. Amortization cost, plus Spacecraft and O&M costs, total $43 per kg of payload. For polar orbit launches, sites exist in Alaska, Russia, and China. For equatorial orbit launches, sites exist in the Andes and Africa. With funding, the Gen-1 system could operate by 2020 AD. The Gen-2 system requires more advanced technology

  9. GeneLab: NASA's Open Access, Collaborative Platform for Systems Biology and Space Medicine

    NASA Technical Reports Server (NTRS)

    Berrios, Daniel C.; Thompson, Terri G.; Fogle, Homer W.; Rask, Jon C.; Coughlan, Joseph C.

    2015-01-01

    NASA is investing in GeneLab1 (http:genelab.nasa.gov), a multi-year effort to maximize utilization of the limited resources to conduct biological and medical research in space, principally aboard the International Space Station (ISS). High-throughput genomic, transcriptomic, proteomic or other omics analyses from experiments conducted on the ISS will be stored in the GeneLab Data Systems (GLDS), an open-science information system that will also include a biocomputation platform with collaborative science capabilities, to enable the discovery and validation of molecular networks.

  10. Changing chromatin fiber conformation by nucleosome repositioning.

    PubMed

    Müller, Oliver; Kepper, Nick; Schöpflin, Robert; Ettig, Ramona; Rippe, Karsten; Wedemann, Gero

    2014-11-04

    Chromatin conformation is dynamic and heterogeneous with respect to nucleosome positions, which can be changed by chromatin remodeling complexes in the cell. These molecular machines hydrolyze ATP to translocate or evict nucleosomes, and establish loci with regularly and more irregularly spaced nucleosomes as well as nucleosome-depleted regions. The impact of nucleosome repositioning on the three-dimensional chromatin structure is only poorly understood. Here, we address this issue by using a coarse-grained computer model of arrays of 101 nucleosomes considering several chromatin fiber models with and without linker histones, respectively. We investigated the folding of the chain in dependence of the position of the central nucleosome by changing the length of the adjacent linker DNA in basepair steps. We found in our simulations that these translocations had a strong effect on the shape and properties of chromatin fibers: i), Fiber curvature and flexibility at the center were largely increased and long-range contacts between distant nucleosomes on the chain were promoted. ii), The highest destabilization of the fiber conformation occurred for a nucleosome shifted by two basepairs from regular spacing, whereas effects of linker DNA changes of ?10 bp in phase with the helical twist of DNA were minimal. iii), A fiber conformation can stabilize a regular spacing of nucleosomes inasmuch as favorable stacking interactions between nucleosomes are facilitated. This can oppose nucleosome translocations and increase the energetic costs for chromatin remodeling. Our computational modeling framework makes it possible to describe the conformational heterogeneity of chromatin in terms of nucleosome positions, and thus advances theoretical models toward a better understanding of how genome compaction and access are regulated within the cell.

  11. Changing Chromatin Fiber Conformation by Nucleosome Repositioning

    PubMed Central

    Müller, Oliver; Kepper, Nick; Schöpflin, Robert; Ettig, Ramona; Rippe, Karsten; Wedemann, Gero

    2014-01-01

    Chromatin conformation is dynamic and heterogeneous with respect to nucleosome positions, which can be changed by chromatin remodeling complexes in the cell. These molecular machines hydrolyze ATP to translocate or evict nucleosomes, and establish loci with regularly and more irregularly spaced nucleosomes as well as nucleosome-depleted regions. The impact of nucleosome repositioning on the three-dimensional chromatin structure is only poorly understood. Here, we address this issue by using a coarse-grained computer model of arrays of 101 nucleosomes considering several chromatin fiber models with and without linker histones, respectively. We investigated the folding of the chain in dependence of the position of the central nucleosome by changing the length of the adjacent linker DNA in basepair steps. We found in our simulations that these translocations had a strong effect on the shape and properties of chromatin fibers: i), Fiber curvature and flexibility at the center were largely increased and long-range contacts between distant nucleosomes on the chain were promoted. ii), The highest destabilization of the fiber conformation occurred for a nucleosome shifted by two basepairs from regular spacing, whereas effects of linker DNA changes of ∼10 bp in phase with the helical twist of DNA were minimal. iii), A fiber conformation can stabilize a regular spacing of nucleosomes inasmuch as favorable stacking interactions between nucleosomes are facilitated. This can oppose nucleosome translocations and increase the energetic costs for chromatin remodeling. Our computational modeling framework makes it possible to describe the conformational heterogeneity of chromatin in terms of nucleosome positions, and thus advances theoretical models toward a better understanding of how genome compaction and access are regulated within the cell. PMID:25418099

  12. Performance of a space-time block coded code division multiple access system over Nakagami-m fading channels

    NASA Astrophysics Data System (ADS)

    Yu, Xiangbin; Dong, Tao; Xu, Dazhuan; Bi, Guangguo

    2010-09-01

    By introducing an orthogonal space-time coding scheme, multiuser code division multiple access (CDMA) systems with different space time codes are given, and corresponding system performance is investigated over a Nakagami-m fading channel. A low-complexity multiuser receiver scheme is developed for space-time block coded CDMA (STBC-CDMA) systems. The scheme can make full use of the complex orthogonality of space-time block coding to simplify the high decoding complexity of the existing scheme. Compared to the existing scheme with exponential decoding complexity, it has linear decoding complexity. Based on the performance analysis and mathematical calculation, the average bit error rate (BER) of the system is derived in detail for integer m and non-integer m, respectively. As a result, a tight closed-form BER expression is obtained for STBC-CDMA with an orthogonal spreading code, and an approximate closed-form BER expression is attained for STBC-CDMA with a quasi-orthogonal spreading code. Simulation results show that the proposed scheme can achieve almost the same performance as the existing scheme with low complexity. Moreover, the simulation results for average BER are consistent with the theoretical analysis.

  13. A monograph of the National Space Transportation System Office (NSTSO) integration activities conducted at the NASA Lyndon B. Johnson Space Center for the EASE/ACCESS payload flown on STS 61-B

    NASA Technical Reports Server (NTRS)

    Chassay, Charles

    1987-01-01

    The integration process of activities conducted at the NASA Lyndon B. Johnson Space Center (JSC) for the Experimental Assembly of Structures in Extravehicular activity (EASE)/Assembly Concept for Construction of Erectable Space Structures (ACCESS) payload is provided as a subset to the standard payload integration process used by the NASA Space Transportation System (STS) to fly payloads on the Space Shuttle. The EASE/ACCESS payload integration activities are chronologically reviewed beginning with the initiation of the flight manifesting and integration process. The development and documentation of the EASE/ACCESS integration requirements are also discussed along with the implementation of the mission integration activities and the engineering assessments supporting the flight integration process. In addition, the STS management support organizations, the payload safety process leading to the STS 61-B flight certification, and the overall EASE/ACCESS integration schedule are presented.

  14. Determination of the solution-bound conformation of an amino acid binding protein by NMR paramagnetic relaxation enhancement: use of a single flexible paramagnetic probe with improved estimation of its sampling space.

    PubMed

    Bermejo, Guillermo A; Strub, Marie-Paule; Ho, Chien; Tjandra, Nico

    2009-07-15

    We demonstrate the feasibility of elucidating the bound ("closed") conformation of a periplasmic binding protein, the glutamine-binding protein (GlnBP), in solution, using paramagnetic relaxation enhancements (PREs) arising from a single paramagnetic group. GlnBP consists of two globular domains connected by a hinge. Using the ligand-free ("open") conformation as a starting point, conjoined rigid-body/torsion-angle simulated annealing calculations were performed using backbone (1)H(N)-PREs as a major source of distance information. Paramagnetic probe flexibility was accounted for via a multiple-conformer representation. A conventional approach where the entire PRE data set is enforced at once during simulated annealing yielded poor results due to inappropriate conformational sampling of the probe. On the other hand, significant improvements in coordinate accuracy were obtained by estimating the probe sampling space prior to structure calculation. Such sampling is achieved by refining the ensemble of probe conformers with intradomain PREs only, keeping the protein backbone fixed in the open form. Subsequently, while constraining the probe to the previously found conformations, the domains are allowed to move relative to each other under the influence of the non-intradomain PREs, giving the hinge region torsional degrees of freedom. Thus, by partitioning the protocol into "probe sampling" and "backbone sampling" stages, structures significantly closer to the X-ray structure of ligand-bound GlnBP were obtained.

  15. Charged conformal Killing spinors

    SciTech Connect

    Lischewski, Andree

    2015-01-15

    We study the twistor equation on pseudo-Riemannian Spin{sup c}-manifolds whose solutions we call charged conformal Killing spinors (CCKSs). We derive several integrability conditions for the existence of CCKS and study their relations to spinor bilinears. A construction principle for Lorentzian manifolds admitting CCKS with nontrivial charge starting from CR-geometry is presented. We obtain a partial classification result in the Lorentzian case under the additional assumption that the associated Dirac current is normal conformal and complete the classification of manifolds admitting CCKS in all dimensions and signatures ≤5 which has recently been initiated in the study of supersymmetric field theories on curved space.

  16. I-mode access and transitions in an expanded operating space on Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Hubbard, A. E.; Baek, S.-G.; Churchill, R. M.; Golfinopoulos, T.; Hughes, J. W.; Lin, Y.; Marmar, E. S.; Terry, J. L.; Theiler, C.; Walk, J. R.; White, A. E.; Whyte, D. G.; Wolfe, S. M.; Wukitch, S. J.; Cziegler, I.; Edlund, E.

    2014-10-01

    New experiments in the I-mode regime on Alcator C-Mod have further expanded the wide range of conditions over which it has been studied. I-mode is attractive in that it combines the high energy confinement of H-mode, up to H98 = 1.2, with the low particle/impurity confinement of L-Mode. Accessing and maintaining the regime, without transitions to L-mode or H-mode, is key to its extrapolation. The most robust conditions on C-Mod have been in lower null plasmas with unfavorable drift and BT of 5-6 T, spanning the ITER value. In 2014, experiments at 2.8 T showed that the power range between L-I and I-H transitions was significantly lower, consistent with results on DIII-D and AUG. I-mode was also accessed in near double null. Fueling into I-modes can raise the density, up to 2×1020 m-3. The upper ne increases with input power. Local pedestal parameters and evolution of turbulence at transitions are being assessed with the aim of understanding the physical mechanisms and for extrapolation. Supported by DOE Award DE-FC02-99ER54512.

  17. How access to exhibit space impacts the behavior of female tigers (Panthera tigris).

    PubMed

    Miller, Angela; Leighty, Katherine A; Maloney, Margaret A; Kuhar, Christopher W; Bettinger, Tamara L

    2011-01-01

    Little is known about how socially housed captive carnivores respond to temporary reductions in available space. We documented rates of aggression and affiliation in our group of six female tigers, under their normal housing conditions and during a period of exhibit renovations which resulted in a 50% reduction in time spent in an outdoor enclosure. During the period of reduced availability of space, significant declines in aggression and affiliation were observed indicating that these tigers responded in a manner consistent with a strategy of conflict avoidance. These reductions in rates of social behavior remained in place during the year following the return to their original housing conditions. Thus, even temporary alterations to housing practices have the potential to have lasting impacts on the social behavior of this species.

  18. United States Human Access to Space, Exploration of the Moon and Preparation for Mars Exploration

    NASA Technical Reports Server (NTRS)

    Rhatigan, Jennifer L.

    2009-01-01

    In the past, men like Leonardo da Vinci and Jules Verne imagined the future and envisioned fantastic inventions such as winged flying machines, submarines, and parachutes, and posited human adventures like transoceanic flight and journeys to the Moon. Today, many of their ideas are reality and form the basis for our modern world. While individual visionaries like da Vinci and Verne are remembered for the accuracy of their predictions, today entire nations are involved in the process of envisioning and defining the future development of mankind, both on and beyond the Earth itself. Recently, Russian, European, and Chinese teams have all announced plans for developing their own next generation human space vehicles. The Chinese have announced their intention to conduct human lunar exploration, and have flown three crewed space missions since 2003, including a flight with three crew members to test their extravehicular (spacewalking) capabilities in September 2008. Very soon, the prestige, economic development, scientific discovery, and strategic security advantage historically associated with leadership in space exploration and exploitation may no longer be the undisputed province of the United States. Much like the sponsors of the seafaring explorers of da Vinci's age, we are motivated by the opportunity to obtain new knowledge and new resources for the growth and development of our own civilization. NASA's new Constellation Program, established in 2005, is tasked with maintaining the United States leadership in space, exploring the Moon, creating a sustained human lunar presence, and eventually extending human operations to Mars and beyond. Through 2008, the Constellation Program developed a full set of detailed program requirements and is now completing the preliminary design phase for the new Orion Crew Exploration Vehicle (CEV), the Ares I Crew Launch Vehicle, and the associated infrastructure necessary for humans to explore the Moon. Component testing is well

  19. U.S. Access to Space Launch Vehicle Choices for 1990-2010

    DTIC Science & Technology

    1990-03-01

    own study of future space goals included a range of options such as increased study of the Earth, unmanned explorr-.oi. of the Solar System, and human...and activity beyond Earth orbit into the solar system.ř This could result in the establishment of a permanently manned lunar base, expeditions to...6, -8, -11, and -14 derived from ballistic missile systems and the SI,12, -13, and -16. The SL-X.17 booster, ’ Energia ," is still undergoing flight

  20. What Happens If They Say No? Preserving Access to Critical Commercial Space Capabilities during Future Crises

    DTIC Science & Technology

    2014-12-01

    Operation Nickel Grass ( ONG ) resupply of Israeli forces. Arab forces used the de- lay to inflict heavy losses on Israeli forces and secure territorial...PLACE The basic lesson from ONG should speak loudly to national security space professionals. Despite Washington’s cachet as a customer, Ameri- can...planning for them now. Failure to do so places the nation at risk of experiencing the same dilemma that oc- curred during ONG . Without meaningful

  1. Orion: Design of a system for assured low-cost human access to space

    NASA Technical Reports Server (NTRS)

    Elvander, Josh; Heifetz, Andy; Hunt, Teresa; Zhu, Martin

    1994-01-01

    In recent years, Congress and the American people have begun to seriously question the role and importance of future manned spaceflight. This is mainly due to two factors: a decline in technical competition caused by the collapse of communism, and the high costs associated with the Space Shuttle transportation system. With these factors in mind, the ORION system was designed to enable manned spaceflight at a low cost, while maintaining the ability to carry out diverse missions, each with a high degree of flexibility. It is capable of performing satellite servicing missions, supporting a space station via crew rotation and resupply, and delivering satellites into geosynchronous orbit. The components of the system are a primary launch module, an upper stage, and a manned spacecraft capable of dynamic reentry. For satellite servicing and space station resupply missions, the ORION system utilizes three primary modules, an upper stage, and the spacecraft, which is delivered to low earth orbit and used to rendezvous, transfer materials, and make repairs. For launching a geosynchronous satellite, one primary module and an upper stage are used to deliver the satellite, along with an apogee kick motor, into orbit. The system is designed with reusability and modularity in mind in an attempt to lower cost.

  2. Rocketdyne Development of RBCC Engine for Low Cost Access to Space

    NASA Technical Reports Server (NTRS)

    Ortwerth, P.; Ratekin, G.; Goldman, A.; Emanuel, M.; Ketchum, A.; Horn, M.

    1997-01-01

    Rocketdyne is pursuing the conceptual design and development of a Rocket Based Combined Cycle (RBCC) engine for booster and SSTO, advanced reusable space transportation ARTT systems under contract with NASA Marshall Space Flight Center. The Rocketdyne concept is fixed geometry integrated Rocket, Ram Scramjet which is Hydrogen fueled and uses Hydrogen regenerative cooling. Vision vehicle integration studies have determined that scramjet operation to Mach 12 has high payoff for low cost reusable space transportation. Rocketdyne is internally developing versions of the concept for other applications in high speed aircraft and missiles with Hydrocarbon fuel systems. Subscale engine ground testing is underway for all modes of operation from takeoff to Mach 8. High altitude Rocket only mode tests will be completed as part of the ground test program to validate high expansion ratio performance. A unique feature of the ground test series is the inclusion of dynamic trajectory simulation with real time Mach number, altitude, engine throttling, and RBCC mode changes in a specially modified freejet test facility at GASL. Preliminary cold flow Air Augmented Rocket mode test results and Short Combustor tests have met program goals and have been used to integrate all modes of operation in a single combustor design with a fixed geometry inlet for design confirmation tests. A water cooled subscale engine is being fabricated and installed for test beginning the last quarter of 1997.

  3. Human factors in space station architecture 2. EVA access facility: A comparative analysis of 4 concepts for on-orbit space suit servicing

    NASA Technical Reports Server (NTRS)

    Cohen, Marc M.; Bussolari, Steven

    1987-01-01

    Four concepts for on-orbit spacesuit donning, doffing, servicing, check-out, egress and ingress are presented. These are: the Space Transportation System (STS) Type (shuttle system enlarged), the Transit Airlock (Shuttle Airlock with suit servicing removed from the pump-down chamber), the Suitport (a rear-entry suit mates to a port in the airlock wall), and the Crewlock (a small, individual, conformal airlock). Each of these four concepts is compared through a series of seven steps representing a typical Extra Vehicular Activity (EVA) mission: (1) Predonning suit preparation; (2) Portable Life Support System (PLSS) preparation; (3) Suit Donning and Final Check; (4) Egress/Ingress; (5) Mid-EVA rest period; (6) Post-EVA Securing; (7) Non-Routine Maintenance. The different characteristics of each concept are articulated through this step-by-step approach. Recommendations concerning an approach for further evaluations of airlock geometry, anthropometrics, ergonomics, and functional efficiency are made. The key recommendation is that before any particular airlock can be designed, the full range of spacesuit servicing functions must be considered, including timelines that are most supportive of EVA human productivity.

  4. Genelab: Scientific Partnerships and an Open-Access Database to Maximize Usage of Omics Data from Space Biology Experiments

    NASA Technical Reports Server (NTRS)

    Reinsch, S. S.; Galazka, J..; Berrios, D. C; Chakravarty, K.; Fogle, H.; Lai, S.; Bokyo, V.; Timucin, L. R.; Tran, P.; Skidmore, M.

    2016-01-01

    NASA's mission includes expanding our understanding of biological systems to improve life on Earth and to enable long-duration human exploration of space. The GeneLab Data System (GLDS) is NASA's premier open-access omics data platform for biological experiments. GLDS houses standards-compliant, high-throughput sequencing and other omics data from spaceflight-relevant experiments. The GeneLab project at NASA-Ames Research Center is developing the database, and also partnering with spaceflight projects through sharing or augmentation of experiment samples to expand omics analyses on precious spaceflight samples. The partnerships ensure that the maximum amount of data is garnered from spaceflight experiments and made publically available as rapidly as possible via the GLDS. GLDS Version 1.0, went online in April 2015. Software updates and new data releases occur at least quarterly. As of October 2016, the GLDS contains 80 datasets and has search and download capabilities. Version 2.0 is slated for release in September of 2017 and will have expanded, integrated search capabilities leveraging other public omics databases (NCBI GEO, PRIDE, MG-RAST). Future versions in this multi-phase project will provide a collaborative platform for omics data analysis. Data from experiments that explore the biological effects of the spaceflight environment on a wide variety of model organisms are housed in the GLDS including data from rodents, invertebrates, plants and microbes. Human datasets are currently limited to those with anonymized data (e.g., from cultured cell lines). GeneLab ensures prompt release and open access to high-throughput genomics, transcriptomics, proteomics, and metabolomics data from spaceflight and ground-based simulations of microgravity, radiation or other space environment factors. The data are meticulously curated to assure that accurate experimental and sample processing metadata are included with each data set. GLDS download volumes indicate strong

  5. Morpheus: a conformation-activity relationships and receptor modeling package.

    PubMed

    Andrews, P R; Quint, G; Winkler, D A; Richardson, D; Sadek, M; Spurling, T H

    1989-09-01

    Our molecular modeling software package, MORPHEUS, allows the study of the interactions between biologically active molecules and their receptors. The package is capable of exploring the multidimensional conformational space accessible to each molecule of the data set under study. By specifying distance constraints or hypothetical receptor binding points, the package is able to filter the biologically accessible conformations of each active compound and deduce a three-dimensional model of the binding sites consistent with the properties of the agonists (or antagonists) under scrutiny. The electrostatic potentials in the environment of a putative binding site can also be investigated using the MORPHEUS package. The molecular modeling module CRYS-X, which is written in FORTRAN 77 for IBM PC machines, is capable of building, displaying and manipulating molecules.

  6. REUSABLE PROPULSION ARCHITECTURE FOR SUSTAINABLE LOW-COST ACCESS TO SPACE

    NASA Technical Reports Server (NTRS)

    Bonometti, Joseph; Frame, Kyle L.; Dankanich, John W.

    2005-01-01

    Two transportation architecture changes are presented at either end of a conventional two-stage rocket flight: 1) Air launch using a large, conventional, pod hauler design (i.e., Crossbow)ans 2) Momentum exchange tether (i.e., an in-space asset like MXER). Air launch has ana analytically justified cost reduction of approx. 10%, but its intangible benefits suggest real-world operations cost reductions much higher: 1) Inherent launch safety; 2) Mission Risk Reduction; 3) Favorable payload/rocket limitations; and 4) Leveraging the aircraft for other uses (military transport, commercial cargo, public outreach activities, etc.)

  7. Ablation modeling of electro-magnetically launched projectile for access to space

    NASA Astrophysics Data System (ADS)

    Gosse, Ryan C.

    It has been proposed to study and identify the technical issues involved in the launch to space of micro-satellite payloads using an airborne electromagnetic launcher (AEML). A computational fluid dynamics (CFD) computer code was developed to help characterize the aerothermal issues involved with the flight of the projectile as it exits the Earth's atmosphere. Conceptual geometries were chosen to evaluate the feasibility of launching to orbit from an aircraft. Due to expected high heating fluxes, carboncarbon material was selected for the thermal protection system (TPS). Results of the conceptual study are presented and used to evaluate the practicality of the AEML concept.

  8. Photosynthetic flagellates as model systems for accessing the impact of space conditions on plants

    NASA Astrophysics Data System (ADS)

    Lebert, Michael; Richter, Peter; Häder, Donat

    Plants are an integral part of the exploration attempts for the planned missions to Mars and Moon. Photosynthetic, motile flagellates like Euglena gracilis can serve as model systems for the better understanding of the impact of microgravity and cosmic radiation on plants. Recent parabolic flights indicate that photosynthesis is impaired by microgravity. While oxygen production decreased during the short-term microgravity phases, other photosynthetic parameters remained constant or increased (photosynthetic yield and Ft as indicated by Pulse Amplitude Modulated Fluorescence measurements (PAM)). Ground-based long-term measurements in static bioreactors indicate a strong circadian rhythm of the related PAM-accessible parameters including oxygen production. Besides the problem of scientific analysis of these findings, practical implications with respect to life support systems or controlled environmental systems (CES) are significant. In two FOTON missions a CES system (AQUACELLS and its successor OMEGAHAB) was flown. The detailed analysis is still ongoing. In the paper oxygen production rates are compared to reference experiments on ground. In addition, the results of an upcoming parabolic flight campaign centred around fast PAM kinetics for a closer understanding of the impaired photosynthetic parameters will be presented.

  9. I(sup STAR), NASA's Next Step in Air-Breathing Propulsion for Space Access

    NASA Technical Reports Server (NTRS)

    Hutt, John J.; McArthur, Craig; Cook, Stephen (Technical Monitor)

    2001-01-01

    The United States' National Aeronautics and Space Administration (NASA) has established a strategic plan for future activities in space. A primary goal of this plan is to make drastic improvements in the cost and safety of earth to low-earth-orbit transportation. One approach to achieving this goal is through the development of highly reusable, highly reliable space transportation systems analogous to the commercial airline system. In the year 2000, NASA selected the Rocket Based Combined Cycle (RBCC) engine as the next logical step towards this goal. NASA will develop a complete flight-weight, pump-fed engine system under the Integrated System Test of an Airbreathing Rocket (I(sup STAR)) Project. The objective of this project is develop a reusable engine capable of self-powering a vehicle through the air-augmented rocket, ramjet and scramjet modes required in all RBCC based operational vehicle concepts. The project is currently approved and funded to develop the engine through ground test demonstration. Plans are in place to proceed with flight demonstration pending funding approval. The project is in formulation phase and the Preliminary Requirements Review has been completed. The engine system and vehicle have been selected at the conceptual level. The I(sup STAR) engine concept is based on an air-breathing flowpath downselected from three configurations evaluated in NASA's Advanced Reusable Technology contract. The selected flowpath features rocket thrust chambers integrated into struts separating modular flowpath ducts, a variable geometry inlet, and a thermally choked throat. The engine will be approximately 220 inches long and 79 inches wide and fueled with a hydrocarbon fuel using liquid oxygen as the primary oxidizer candidate. The primary concept for the pump turbine drive is pressure-fed catalyzed hydrogen peroxide. In order to control costs, the flight demonstration vehicle will be launched from a B-52 aircraft. The vehicle concept is based on the Air

  10. Space Science IS Accessible to Students with Exceptional Needs: Results from Exceptional Needs Workshops

    NASA Astrophysics Data System (ADS)

    Runyon, C. J.; Merritt, M.; Guimond, K.

    2003-12-01

    The majority of students with disabilities in the US are required to achieve the same academic levels as their non-impaired peers. Unfortunately, there are few specialized materials to help these exceptional students. To assist students in meeting their goals, SERCH, a NASA Office of Space Science Broker/Facilitator, has been working with NASA education product developers and educators from informal and formal settings to identify what kinds of materials they need and what mediums will work best. As a result of both direct classrooms observations and hands-on workshops we have begun generating adaptive lessons plans that meet the national standards for Science, Technology, Engineering and Mathematics. During the workshops, participants simulate various disabilities (e.g., hearing, vision, orthopedic impairments, learning difficulties) while working through Space Science activities and discuss necessary adaptations/modifications in real-time. For example, we modified the Solar System Distance activity first designed by ASU to include the use of larger beads or pom-poms instead of the suggested small plastic beads. This simple adaptation permits students with orthopedic impairments to more readily take part in the lesson and to actively "observe" the distance between the planets. Examples of this activity and more will be illustrated. In addition to making modifications and suggestions for adaptations, workshop participants shared many simple recommendations that can help ALL learners participate more readily in classroom activities and discussions. Among these are: (1) Use simple, sans-serif fonts and high contrast presentation media (e.g., white text on black is most effective); (2) Repetition and use of multiple presentation modes is very helpful. (3) Actively involve the learner, and (4) Keep things simple to begin with, then work toward the more complex - think of the audience, the ultimate user.

  11. Scale invariance vs conformal invariance

    NASA Astrophysics Data System (ADS)

    Nakayama, Yu

    2015-03-01

    In this review article, we discuss the distinction and possible equivalence between scale invariance and conformal invariance in relativistic quantum field theories. Under some technical assumptions, we can prove that scale invariant quantum field theories in d = 2 space-time dimensions necessarily possess the enhanced conformal symmetry. The use of the conformal symmetry is well appreciated in the literature, but the fact that all the scale invariant phenomena in d = 2 space-time dimensions enjoy the conformal property relies on the deep structure of the renormalization group. The outstanding question is whether this feature is specific to d = 2 space-time dimensions or it holds in higher dimensions, too. As of January 2014, our consensus is that there is no known example of scale invariant but non-conformal field theories in d = 4 space-time dimensions under the assumptions of (1) unitarity, (2) Poincaré invariance (causality), (3) discrete spectrum in scaling dimensions, (4) existence of scale current and (5) unbroken scale invariance in the vacuum. We have a perturbative proof of the enhancement of conformal invariance from scale invariance based on the higher dimensional analogue of Zamolodchikov's c-theorem, but the non-perturbative proof is yet to come. As a reference we have tried to collect as many interesting examples of scale invariance in relativistic quantum field theories as possible in this article. We give a complementary holographic argument based on the energy-condition of the gravitational system and the space-time diffeomorphism in order to support the claim of the symmetry enhancement. We believe that the possible enhancement of conformal invariance from scale invariance reveals the sublime nature of the renormalization group and space-time with holography. This review is based on a lecture note on scale invariance vs conformal invariance, on which the author gave lectures at Taiwan Central University for the 5th Taiwan School on Strings and

  12. The Fab Conformations in the Solution Structure of Human Immunoglobulin G4 (IgG4) Restrict Access to Its Fc Region

    PubMed Central

    Rayner, Lucy E.; Hui, Gar Kay; Gor, Jayesh; Heenan, Richard K.; Dalby, Paul A.; Perkins, Stephen J.

    2014-01-01

    Human IgG4 antibody shows therapeutically useful properties compared with the IgG1, IgG2, and IgG3 subclasses. Thus IgG4 does not activate complement and shows conformational variability. These properties are attributable to its hinge region, which is the shortest of the four IgG subclasses. Using high throughput scattering methods, we studied the solution structure of wild-type IgG4(Ser222) and a hinge mutant IgG4(Pro222) in different buffers and temperatures where the proline substitution suppresses the formation of half-antibody. Analytical ultracentrifugation showed that both IgG4 forms were principally monomeric with sedimentation coefficients s20,w0 of 6.6–6.8 S. A monomer-dimer equilibrium was observed in heavy water buffer at low temperature. Scattering showed that the x-ray radius of gyration Rg was unchanged with concentration in 50–250 mm NaCl buffers, whereas the neutron Rg values showed a concentration-dependent increase as the temperature decreased in heavy water buffers. The distance distribution curves (P(r)) revealed two peaks, M1 and M2, that shifted below 2 mg/ml to indicate concentration-dependent IgG4 structures in addition to IgG4 dimer formation at high concentration in heavy water. Constrained x-ray and neutron scattering modeling revealed asymmetric solution structures for IgG4(Ser222) with extended hinge structures. The IgG4(Pro222) structure was similar. Both IgG4 structures showed that their Fab regions were positioned close enough to the Fc region to restrict C1q binding. Our new molecular models for IgG4 explain its inability to activate complement and clarify aspects of its stability and function for therapeutic applications. PMID:24876381

  13. The History and Promise of Combined Cycle Engines for Access to Space Applications

    NASA Technical Reports Server (NTRS)

    Clark, Casie

    2010-01-01

    For the summer of 2010, I have been working in the Aerodynamics and Propulsion Branch at NASA Dryden Flight Research Center studying combined-cycle engines, a high speed propulsion concept. Combined cycle engines integrate multiple propulsion systems into a single engine capable of running in multiple modes. These different modes allow the engine to be extremely versatile and efficient in varied flight conditions. The two most common types of combined cycle engines are Rocket-Based Combined Cycle (RBCC) and Turbine Based Combined Cycle (TBCC). The RBCC essentially combines a rocket and ramjet engine, while the TBCC integrates a turbojet and ramjet1. These two engines are able to switch between different propulsion modes to achieve maximum performance. Extensive conceptual and ground test studies of RBCC engines have been undertaken; however, an RBCC engine has never, to my knowledge, been demonstrated in flight. RBCC engines are of particular interest because they could potentially power a reusable launch vehicle (RLV) into space. The TBCC has been flight tested and shown to be effective at reaching supersonic speeds, most notably in the SR-71 Blackbird2.

  14. Commentary on accessing 3-D currents in space: Experiences from Cluster

    NASA Astrophysics Data System (ADS)

    Dunlop, M. W.; Haaland, S.; Escoubet, P. C.; Dong, X.-C.

    2016-08-01

    The curlometer was introduced to estimate the electric current density from four-point measurements in space; anticipating the realization of the four spacecraft Cluster mission which began full science operations in February 2001. The method uses Ampère's law to estimate current from the magnetic field measurements, suitable for the high-conductivity plasma of the magnetosphere and surrounding regions. The accuracy of the method is limited by the spatial separation knowledge, accuracy of the magnetic field measurement, and the relative scale size of the current structures sampled but nevertheless has proven to be robust and reliable in many regions of the magnetosphere. The method has been applied successfully and has been a key element, in studies of the magnetopause currents; the magnetotail current sheet; and the ring current, as well as allowing other current structures such as flux tubes and field aligned currents to be determined. The method is also applicable to situations where less than four spacecraft are closely grouped or where special assumptions (particularly stationarity) can be made. In view of the new four-point observations of the MMS mission taking place now, which cover a dramatically different spatial regime, we comment on the performance, adaptability, and lessons learnt from the curlometer technique. We emphasize the adaptability of the method, in particular, to the new sampling regime offered by the MMS mission; thereby offering a tool to address open questions on small-scale current structures.

  15. Mechanism for alternating access in neurotransmitter transporters.

    PubMed

    Forrest, Lucy R; Zhang, Yuan-Wei; Jacobs, Miriam T; Gesmonde, Joan; Xie, Li; Honig, Barry H; Rudnick, Gary

    2008-07-29

    Crystal structures of LeuT, a bacterial homologue of mammalian neurotransmitter transporters, show a molecule of bound substrate that is essentially exposed to the extracellular space but occluded from the cytoplasm. Thus, there must exist an alternate conformation for LeuT in which the substrate is accessible to the cytoplasm and a corresponding mechanism that switches accessibility from one side of the membrane to the other. Here, we identify the cytoplasmic accessibility pathway of the alternate conformation in a mammalian serotonin transporter (SERT) (a member of the same transporter family as LeuT). We also propose a model for the cytoplasmic-facing state that exploits the internal pseudosymmetry observed in the crystal structure. LeuT contains two structurally similar repeats (TMs1-5 and TMs 6-10) that are inverted with respect to the plane of the membrane. The conformational differences between them result in the formation of the extracellular pathway. Our model for the cytoplasm-facing state exchanges the conformations of the two repeats and thus exposes the substrate and ion-binding sites to the cytoplasm. The conformational change that connects the two states primarily involves the tilting of a 4-helix bundle composed of transmembrane helices 1, 2, 6, and 7. Switching the tilt angle of this bundle is essentially equivalent to switching the conformation of the two repeats. Extensive mutagenesis of SERT and accessibility measurements, using cysteine reagents, are accommodated by our model. These observations may be of relevance to other transporter families, many of which contain internal inverted repeats.

  16. Methodology and Results of the Near-Earth Object (NEO) Human Space Flight (HSF) Accessible Targets Study (NHATS)

    NASA Technical Reports Server (NTRS)

    Barbee, Brent; Mink, Ronald; Adamo, Daniel

    2011-01-01

    Near-Earth Asteroids (NEAs) have been identified by the current administration as potential destinations for human explorers during the mid-2020s. While the close proximity of these objects' orbits to Earth's orbit creates a risk of highly damaging or catastrophic impacts, it also makes some of these objects particularly accessible to spacecraft departing Earth, and this presents unique opportunities for solar system science and humanity's first ventures beyond cislunar space. Planning such ambitious missions first requires the selection of potentially accessible targets from the growing population of nearly 7,800 NEAs. To accomplish this, NASA is conducting the Near-Earth Object (NEO) Human Space Flight (HSF) Accessible Targets Study (NHATS). Phase I of the NHATS was executed during September of 2010, and Phase II was completed by early March of 2011. The study is ongoing because previously undetected NEAs are being discovered constantly, which has motivated an effort to automate the analysis algorithms in order to provide continuous monitoring of NEA accessibility. The NHATS analysis process consists of a trajectory filter and a minimum maximum estimated size criterion. The trajectory filter employs the method of embedded trajectory grids to compute all possible ballistic round-trip mission trajectories to every NEA in the Jet Propulsion Laboratory (JPL) Small-Body Database (SBDB) and stores all solutions that satisfy the trajectory filter criteria. An NEA must offer at least one qualifying trajectory solution to pass the trajectory filter. The Phase II NHATS filter criteria were purposely chosen to be highly inclusive, requiring Earth departure date between January 1st, 2015 and December 31st, 2040, total round-trip flight time <= 450 days, stay time at the NEA >= 8 days, Earth departure C(sub 3) energy <= 60 km(exp 2)/s(exp 2), total mission delta-v <= 12 km/s (including an Earth departure maneuver from a 400 km altitude circular parking orbit), and a maximum

  17. A molecular mechanics study of the effect of substitution in position 1 on the conformational space of the oxytocin/vasopressin ring

    NASA Astrophysics Data System (ADS)

    Tarnowska, Monika; Liwo, Adam; Shenderovich, Mark D.; Liepiņa, Inta; Golbraikh, Alexander A.; Grzonka, Zbigniew; Tempczyk, Anna

    1993-12-01

    The effect of the substitution in position 1 on the low-energy conformations of the oxytocin/vasopressin 20-membered ring was investigated by means of molecular mechanics. Three representative substitutions were considered: β'-mercapto-β,β-dimethyl)propionic acid (Dmp), (β'-mercapto-β,β-cyclopentamethylene)propionic acid (Cpp), both forming strong antagonists, and (α,α-dimethyl-β-mercapto)propionic acid (α-Dmp), forming analogs of strongly reduced biological activity, with the β-mercaptopropionic (Mpa) residue taken as reference. Both ECEPP/2 (rigid valence geometry) and AMBER (flexible valence geometry) force fields were employed in the calculations. Three basic types of backbone conformations were taken into account which are distinguished by the type of β-turn at residues 3 and 4: β1/βIII, βII, and βI'/βIII', all types containing one or two intra-annular hydrogen bonds. The allowed (ring-closed) disulfide-bridge conformations were searched by an algorithm formulated in terms of scanning the disulfide-bridge torsional angle Cβ-S-S-Cβ. The ECEPP/2 and AMBER energies of the obtained conformations were found to be in reasonable agreement. Two of the low-energy conformers of the [Mpa1]-compound agreed very well with the cyclic part of the two conformers found in the crystal structure of [Mpa1]-oxytocin. An analysis of the effect of β-substitution on relative energies showed that the conformations with the N-C'-CH2-CH2 (ψ'1) and C'-CH2-CH2-S (ϰ'1) angles of the first residue around (-100°, 60°) and (100°, -60°) are not affected; this in most cases implies a left-handed disulfide bridge. In the case of α-substitution the allowed values of ψ'1 are close to ± 60°. This requirement, being in contradiction to the one concerning β-substitution, could explain the very low biological activity of the α-substituted analogs. The conformational preferences of substituted compounds can largely be explained by the analysis of local interactions

  18. Crystalline arrays of pairs of molecular rotors: correlated motion, rotational barriers, and space-inversion symmetry breaking due to conformational mutations.

    PubMed

    Lemouchi, Cyprien; Iliopoulos, Konstantinos; Zorina, Leokadiya; Simonov, Sergey; Wzietek, Pawel; Cauchy, Thomas; Rodríguez-Fortea, Antonio; Canadell, Enric; Kaleta, Jiří; Michl, Josef; Gindre, Denis; Chrysos, Michael; Batail, Patrick

    2013-06-26

    The rod-like molecule bis((4-(4-pyridyl)ethynyl)bicyclo[2.2.2]oct-1-yl)buta-1,3-diyne, 1, contains two 1,4-bis(ethynyl)bicyclo[2.2.2]octane (BCO) chiral rotators linked by a diyne fragment and self-assembles in a one-dimensional, monoclinic C2/c centrosymmetric structure where two equilibrium positions with large occupancy imbalance (88% versus 12%) are identified on a single rotor site. Combining variable-temperature (70-300 K) proton spin-lattice relaxation, (1)H T1(-1), at two different (1)H Larmor frequencies (55 and 210 MHz) and DFT calculations of rotational barriers, we were able to assign two types of Brownian rotators with different activation energies, 1.85 and 6.1 kcal mol(-1), to the two (1)H spin-lattice relaxation processes on the single rotor site. On the basis of DFT calculations, the low-energy process has been assigned to adjacent rotors in a well-correlated synchronous motion, whereas the high-energy process is the manifestation of an abrupt change in their kinematics once two blades of adjacent rotors are seen to rub together. Although crystals of 1 should be second harmonic inactive, a large second-order optical response is recorded when the electric field oscillates in a direction parallel to the unique rotor axle director. We conclude that conformational mutations by torsional interconversion of the three blades of the BCO units break space-inversion symmetry in sequences of mutamers in dynamic equilibrium in the crystal in domains at a mesoscopic scale comparable with the wavelength of light used. A control experiment was performed with a crystalline film of a similar tetrayne molecule, 1,4-bis(3-((trimethylsilyl)ethynyl)bicyclo[1.1.1]pent-1-yl)buta-1,3-diyne, whose bicyclopentane units can rotate but are achiral and produce no second-order optical response.

  19. Eikonalization of conformal blocks

    SciTech Connect

    Fitzpatrick, A. Liam; Kaplan, Jared; Walters, Matthew T.; Wang, Junpu

    2015-09-03

    Classical field configurations such as the Coulomb potential and Schwarzschild solution are built from the t-channel exchange of many light degrees of freedom. We study the CFT analog of this phenomenon, which we term the 'eikonalization' of conformal blocks. We show that when an operator T appears in the OPE Ο(x)Ο(0), then the large spin Fock space states [TT···T] also appear in this OPE with a computable coefficient. The sum over the exchange of these Fock space states in an correlator build the classical 'T field' in the dual AdS description. In some limits the sum of all Fock space exchanges can be represented as the exponential of a single T exchange in the 4-pt correlator of O. Our results should be useful for systematizing 1/ℓ perturbation theory in general CFTs and simplifying the computation of large spin OPE coefficients. As examples we obtain the leading log ℓ dependence of Fock space conformal block coefficients, and we directly compute the OPE coefficients of the simplest ‘triple-trace’ operators.

  20. Computational Design of Experiment Unveils the Conformational Reaction Coordinate of GH125 α-Mannosidases.

    PubMed

    Alonso-Gil, Santiago; Males, Alexandra; Fernandes, Pearl Z; Williams, Spencer J; Davies, Gideon J; Rovira, Carme

    2017-01-25

    Conformational analysis of enzyme-catalyzed mannoside hydrolysis has revealed two predominant conformational itineraries through B2,5 or (3)H4 transition-state (TS) conformations. A prominent unassigned catalytic itinerary is that of exo-1,6-α-mannosidases belonging to CAZy family 125. A published complex of Clostridium perfringens GH125 enzyme with a nonhydrolyzable 1,6-α-thiomannoside substrate mimic bound across the active site revealed an undistorted (4)C1 conformation and provided no insight into the catalytic pathway of this enzyme. We show through a purely computational approach (QM/MM metadynamics) that sulfur-for-oxygen substitution in the glycosidic linkage fundamentally alters the energetically accessible conformational space of a thiomannoside when bound within the GH125 active site. Modeling of the conformational free energy landscape (FEL) of a thioglycoside strongly favors a mechanistically uninformative (4)C1 conformation within the GH125 enzyme active site, but the FEL of corresponding O-glycoside substrate reveals a preference for a Michaelis complex in an (O)S2 conformation (consistent with catalysis through a B2,5 TS). This prediction was tested experimentally by determination of the 3D X-ray structure of the pseudo-Michaelis complex of an inactive (D220N) variant of C. perfringens GH125 enzyme in complex with 1,6-α-mannobiose. This complex revealed unambiguous distortion of the -1 subsite mannoside to an (O)S2 conformation, matching that predicted by theory and supporting an (O)S2 → B2,5 → (1)S5 conformational itinerary for GH125 α-mannosidases. This work highlights the power of the QM/MM approach and identified shortcomings in the use of nonhydrolyzable substrate analogues for conformational analysis of enzyme-bound species.

  1. Free-space optics technology employed in an UMTS release 4 bearer independent core network access part

    NASA Astrophysics Data System (ADS)

    Bibac, Ionut

    2005-08-01

    The UMTS Bearer Independent Core Network program introduced the 3rd Generation Partnership Program Release 4 BICN architecture into the legacy UMTS TDM-switched network. BICN is the application of calI server archltecture for voice and circuit switched data, enabling the provisioning of traditional circuit-switched services using a packet-switched transport network. Today"s business climate has made it essential for service providers to develop a comprehensive networking strategy that means introduction of RCBICN networks. The R4-BICN solution to the evolution of the Core Network in UMTS will enable operators to significantly reduce the capital and operational costs of delivering both traditional voice sewices and new multimedia services. To build the optical backbone, which can support the third generation (3G) packetized infrastructure, the operators could choose a fibre connection, or they could retain the benefits of a wireless connectivity by using a FSO - Free Space Optical lmk, the only wireless technology available that is capable of achieving data rates up to 2.4 Gbit/s. FSO offers viable alternatives for both core transmission networks and for replacing microwaves links in NodeB - RNC access networks. The paper and presentation aim to demonstrate the manner in which FSO products and networks are employed into R4-BICN design solutions.

  2. Access to space

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The goal of this conceptual design was to devise a reusable, commercially viable, single-stage-to-orbit vehicle. The vehicle has the ability to deliver a 9100 kg (20,000 lb) payload to a low earth orbit of 433 km to 933 km (250 n.mi. - 450 n.mi.). The SSTO vehicle is 51 meters in length and has a gross takeoff mass of 680,400 kg (1,500,000 lb). The vehicle incorporates three RD-701 engines for the main propulsion system and two RL-10 engines for the orbital maneuvering system. The vehicle is designed for a three day stay on orbit with two crew members.

  3. Beyond Rotatable Bond Counts: Capturing 3D Conformational Flexibility in a Single Descriptor

    PubMed Central

    2016-01-01

    A new molecular descriptor, nConf20, based on chemical connectivity, is presented which captures the accessible conformational space of a molecule. Currently the best available two-dimensional descriptors for quantifying the flexibility of a particular molecule are the rotatable bond count (RBC) and the Kier flexibility index. We present a descriptor which captures this information by sampling the conformational space of a molecule using the RDKit conformer generator. Flexibility has previously been identified as a key feature in determining whether a molecule is likely to crystallize or not. For this application, nConf20 significantly outperforms previously reported single-variable classifiers and also assists rule-based analysis of black-box machine learning classification algorithms. PMID:28024401

  4. Beyond Rotatable Bond Counts: Capturing 3D Conformational Flexibility in a Single Descriptor.

    PubMed

    Wicker, Jerome G P; Cooper, Richard I

    2016-12-27

    A new molecular descriptor, nConf20, based on chemical connectivity, is presented which captures the accessible conformational space of a molecule. Currently the best available two-dimensional descriptors for quantifying the flexibility of a particular molecule are the rotatable bond count (RBC) and the Kier flexibility index. We present a descriptor which captures this information by sampling the conformational space of a molecule using the RDKit conformer generator. Flexibility has previously been identified as a key feature in determining whether a molecule is likely to crystallize or not. For this application, nConf20 significantly outperforms previously reported single-variable classifiers and also assists rule-based analysis of black-box machine learning classification algorithms.

  5. Quantification of free ligand conformational preferences by NMR and their relationship to the bioactive conformation.

    PubMed

    Blundell, Charles D; Packer, Martin J; Almond, Andrew

    2013-09-01

    Accurate unbound solution 3D-structures of ligands provide unique opportunities for medicinal chemistry and, in particular, a context to understand binding thermodynamics and kinetics. Previous methods of deriving these 3D-structures have had neither the accuracy nor resolution needed for drug design and have not yet realized their potential. Here, we describe and apply a NMR methodology to the aminoglycoside streptomycin that can accurately quantify accessible 3D-space and rank the occupancy of observed conformers to a resolution that enables medicinal chemistry understanding and design. Importantly, it is based upon conventional small molecule NMR techniques and can be performed in physiologically-relevant solvents. The methodology uses multiple datasets, an order of magnitude more experimental data than previous NMR approaches and a dynamic model during refinement, is independent of computational chemistry and avoids the problem of virtual conformations. The refined set of solution 3D-shapes for streptomycin can be grouped into two major families, of which the most populated is almost identical to the 30S ribosomal subunit bioactive shape. We therefore propose that accurate unbound ligand solution conformations may, in some cases, provide a subsidiary route to bioactive shape without crystallography. This experimental technique opens up new opportunities for drug design and more so when complemented with protein co-crystal structures, SAR data and pharmacophore modeling.

  6. Eikonalization of conformal blocks

    DOE PAGES

    Fitzpatrick, A. Liam; Kaplan, Jared; Walters, Matthew T.; ...

    2015-09-03

    Classical field configurations such as the Coulomb potential and Schwarzschild solution are built from the t-channel exchange of many light degrees of freedom. We study the CFT analog of this phenomenon, which we term the 'eikonalization' of conformal blocks. We show that when an operator T appears in the OPE Ο(x)Ο(0), then the large spin Fock space states [TT···T]ℓ also appear in this OPE with a computable coefficient. The sum over the exchange of these Fock space states in an correlator build the classical 'T field' in the dual AdS description. In some limits the sum of all Fock spacemore » exchanges can be represented as the exponential of a single T exchange in the 4-pt correlator of O. Our results should be useful for systematizing 1/ℓ perturbation theory in general CFTs and simplifying the computation of large spin OPE coefficients. As examples we obtain the leading log ℓ dependence of Fock space conformal block coefficients, and we directly compute the OPE coefficients of the simplest ‘triple-trace’ operators.« less

  7. Chip-interleaved optical code division multiple access relying on a photon-counting iterative successive interference canceller for free-space optical channels.

    PubMed

    Zhou, Xiaolin; Zheng, Xiaowei; Zhang, Rong; Hanzo, Lajos

    2013-07-01

    In this paper, we design a novel Poisson photon-counting based iterative successive interference cancellation (SIC) scheme for transmission over free-space optical (FSO) channels in the presence of both multiple access interference (MAI) as well as Gamma-Gamma atmospheric turbulence fading, shot-noise and background light. Our simulation results demonstrate that the proposed scheme exhibits a strong MAI suppression capability. Importantly, an order of magnitude of BER improvements may be achieved compared to the conventional chip-level optical code-division multiple-access (OCDMA) photon-counting detector.

  8. Ultrahigh-capacity access network architecture for mobile data backhaul using integrated W-band wireless and free-space optical links with OAM multiplexing.

    PubMed

    Fang, Yuan; Yu, Jianjun; Zhang, Junwen; Chi, Nan; Xiao, Jiangnan; Chang, Gee-Kung

    2014-07-15

    In this Letter, we propose and experimentally demonstrate a novel access network architecture using hybrid integrated W-band wireless and free-space optical (FSO) links with orbital angular momentum (OAM) multiplexing. The transmission of a 20 GBd quadrature phase-shift keying signal modulated over 10 OAM modes has been demonstrated over a 0.6 m FSO link and a 0.4 m W-band wireless link at 100 GHz. The experimental results show that the architecture can support future ultrahigh-capacity, converged optical-wireless access networks that require extra bandwidth and system flexibility in mobile data networks.

  9. Universality class in conformal inflation

    SciTech Connect

    Kallosh, Renata; Linde, Andrei E-mail: alinde@stanford.edu

    2013-07-01

    We develop a new class of chaotic inflation models with spontaneously broken conformal invariance. Observational consequences of a broad class of such models are stable with respect to strong deformations of the scalar potential. This universality is a critical phenomenon near the point of enhanced symmetry, SO(1,1), in case of conformal inflation. It appears because of the exponential stretching of the moduli space and the resulting exponential flattening of scalar potentials upon switching from the Jordan frame to the Einstein frame in this class of models. This result resembles stretching and flattening of inhomogeneities during inflationary expansion. It has a simple interpretation in terms of velocity versus rapidity near the Kähler cone in the moduli space, similar to the light cone of special theory of relativity. This effect makes inflation possible even in the models with very steep potentials. We describe conformal and superconformal versions of this cosmological attractor mechanism.

  10. Application of time series analysis on molecular dynamics simulations of proteins: A study of different conformational spaces by principal component analysis

    NASA Astrophysics Data System (ADS)

    Alakent, Burak; Doruker, Pemra; Camurdan, Mehmet C.

    2004-09-01

    Time series analysis is applied on the collective coordinates obtained from principal component analysis of independent molecular dynamics simulations of α-amylase inhibitor tendamistat and immunity protein of colicin E7 based on the Cα coordinates history. Even though the principal component directions obtained for each run are considerably different, the dynamics information obtained from these runs are surprisingly similar in terms of time series models and parameters. There are two main differences in the dynamics of the two proteins: the higher density of low frequencies and the larger step sizes for the interminima motions of colicin E7 than those of α-amylase inhibitor, which may be attributed to the higher number of residues of colicin E7 and/or the structural differences of the two proteins. The cumulative density function of the low frequencies in each run conforms to the expectations from the normal mode analysis. When different runs of α-amylase inhibitor are projected on the same set of eigenvectors, it is found that principal components obtained from a certain conformational region of a protein has a moderate explanation power in other conformational regions and the local minima are similar to a certain extent, while the height of the energy barriers in between the minima significantly change. As a final remark, time series analysis tools are further exploited in this study with the motive of explaining the equilibrium fluctuations of proteins.

  11. Scattering Via Conformal Higher Spin Exchanges

    NASA Astrophysics Data System (ADS)

    Tseytlin, A. A.

    We consider a model of massless scalars interacting (via bilinear conserved currents) with conformal higher spin fields in flat space. We compute the tree-level four-scalar scattering amplitude using a natural prescription for summation over an infinite set of conformal higher spin exchanges and find that it vanishes. Independently, we show that the vanishing of the scalar scattering amplitude is, in fact, implied by the global conformal higher spin symmetry of this model.

  12. Conformal mechanics

    SciTech Connect

    Gonera, Joanna

    2013-08-15

    The SL(2,R) invariant Hamiltonian systems are discussed within the framework of the orbit method. It is shown that both the dynamics and the symmetry transformations are globally well-defined on phase space. The flexibility in the choice of the time variable and the Hamiltonian function described in the paper by de Alfaro et al. [Nuovo Cimento 34A (1976) 569] is related to the nontrivial global structure of 1+0-dimensional space–time. The operational definition of time is discussed.

  13. Protein conformational populations and functionally relevant substates.

    PubMed

    Ramanathan, Arvind; Savol, Andrej; Burger, Virginia; Chennubhotla, Chakra S; Agarwal, Pratul K

    2014-01-21

    Functioning proteins do not remain fixed in a unique structure, but instead they sample a range of conformations facilitated by motions within the protein. Even in the native state, a protein exists as a collection of interconverting conformations driven by thermodynamic fluctuations. Motions on the fast time scale allow a protein to sample conformations in the nearby area of its conformational landscape, while motions on slower time scales give it access to conformations in distal areas of the landscape. Emerging evidence indicates that protein landscapes contain conformational substates with dynamic and structural features that support the designated function of the protein. Nuclear magnetic resonance (NMR) experiments provide information about conformational ensembles of proteins. X-ray crystallography allows researchers to identify the most populated states along the landscape, and computational simulations give atom-level information about the conformational substates of different proteins. This ability to characterize and obtain quantitative information about the conformational substates and the populations of proteins within them is allowing researchers to better understand the relationship between protein structure and dynamics and the mechanisms of protein function. In this Account, we discuss recent developments and challenges in the characterization of functionally relevant conformational populations and substates of proteins. In some enzymes, the sampling of functionally relevant conformational substates is connected to promoting the overall mechanism of catalysis. For example, the conformational landscape of the enzyme dihydrofolate reductase has multiple substates, which facilitate the binding and the release of the cofactor and substrate and catalyze the hydride transfer. For the enzyme cyclophilin A, computational simulations reveal that the long time scale conformational fluctuations enable the enzyme to access conformational substates that allow

  14. Conformal and projective symmetries in Newtonian cosmology

    NASA Astrophysics Data System (ADS)

    Duval, C.; Gibbons, G. W.; Horváthy, P. A.

    2017-02-01

    Definitions of non-relativistic conformal transformations are considered both in the Newton-Cartan and in the Kaluza-Klein-type Eisenhart/Bargmann geometrical frameworks. The symmetry groups that come into play are exemplified by the cosmological, and also the Newton-Hooke solutions of Newton's gravitational field equations. It is shown, in particular, that the maximal symmetry group of the standard cosmological model is isomorphic to the 13-dimensional conformal-Newton-Cartan group whose conformal-Bargmann extension is explicitly worked out. Attention is drawn to the appearance of independent space and time dilations, in contrast with the Schrödinger group or the Conformal Galilei Algebra.

  15. Steinberg conformal algebras

    NASA Astrophysics Data System (ADS)

    Mikhalev, A. V.; Pinchuk, I. A.

    2005-06-01

    The structure of Steinberg conformal algebras is studied; these are analogues of Steinberg groups (algebras, superalgebras).A Steinberg conformal algebra is defined as an abstract algebra by a system of generators and relations between the generators. It is proved that a Steinberg conformal algebra is the universal central extension of the corresponding conformal Lie algebra; the kernel of this extension is calculated.

  16. Bridging the Digital Divide between Discrete and Continuous Space-Time Array Data to Enhance Accessibility to and Usability of NASA Earth Sciences Data for the Hydrological Community

    NASA Astrophysics Data System (ADS)

    Teng, W. L.; Maidment, D. R.; Vollmer, B.; Peters-Lidard, C. D.; Rui, H.; Strub, R.; Whiteaker, T.; Mocko, D. M.; Kirschbaum, D. B.

    2012-12-01

    A longstanding and significant "Digital Divide" in data representation exists between hydrology and climatology and meteorology. Typically, in hydrology, earth surface features are expressed as discrete spatial objects such as watersheds, river reaches, and point observation sites; and time varying data are contained in time series associated with these spatial objects. Long time histories of data may be associated with a single point or feature in space. In meteorology and climatology, remotely sensed observations and weather and climate model information are expressed as continuous spatial fields, with data sequenced in time from one data file to the next. Hydrology tends to be narrow in space and deep in time, while meteorology and climatology are broad in space and narrow in time. This Divide has been an obstacle, specifically, between the hydrological community, as represented by the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) and relevant data sets at the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC). CUAHSI has developed the Hydrologic Information System (HIS), which is built on international geospatial standards, with one of its aims to bridge the Divide. The opportunity costs of the Divide are high. It has largely prevented the routine access and use of NASA Earth sciences data by the hydrological and, more generally, geospatial community. This presentation describes a recently-begun NASA ACCESS project that addresses the Digital Divide problem. Progress to date is summarized; technical details are provided in a related presentation (Rui et al., Data Reorganization for Optimal Time Series Data Access, Analysis, and Visualization, IN016). Building on prior prototype efforts with EPA BASINS (Better Assessment Science Integrating point and Nonpoint Sources) and CUAHSI HIS, this project focuses on the following approaches to the problems of data discovery, access, and use: (1) Link HIS and

  17. On the conformation of the propranolol molecule

    NASA Astrophysics Data System (ADS)

    Sadlej-Sosnowska, N.; Dobrowolski, J. Cz; Mazurek, A. P.

    2000-03-01

    The structure of the propranolol molecule has been optimized within the AM1 and PM3 semiempirical framework followed by ab initio HF/6-31G ∗ refinement. On each calculation level the conformational space was sampled to search for the lowest-energy conformer(s) from among a few hundreds of conformers at the semiempirical step and next from among a few dozens of conformers at the ab initio level. Finally, five stable conformers were found; each stabilized by one or two of the three possible hydrogen bonds. The geometrical and electronic parameters were established and found to differ only slightly in the structures with the hydrogen bond either present or not.

  18. Bases and spaces: resources on the web for accessing the draft human genome - II - After publication of the draft

    PubMed Central

    Semple, Colin AM

    2001-01-01

    The volume of human genome sequence and the variety of web-based tools to access it continue to grow at an impressive rate, but a working knowledge of certain key resources can be sufficient to get the most from your genome. This article provides an update to Genome Biology 2000, 1(4):reviews2001.1-2001.5. PMID:11423014

  19. Is access to neighborhood green space associated with BMI among Egyptians? A multilevel study of Cairo neighborhoods.

    PubMed

    Mowafi, Mona; Khadr, Zeinab; Bennett, Gary; Hill, Allan; Kawachi, Ichiro; Subramanian, S V

    2012-03-01

    Evidence of a link between green space and obesity has increased in the developed world, but few studies have been conducted in the developing world. Our study tests whether availability of neighborhood green space is associated with BMI among adults in Cairo, Egypt. Using data from the 2007 Cairo Urban Inequity Study, we conducted multilevel analyses and found no significant green space-BMI association, leading us to conclude that this intervention may not be as promising in this developing world context as it has been in some western urban contexts. Other aspects of the urban environment should be evaluated to better understand neighborhood variations in obesity in Cairo.

  20. Self-Dual Conformal Gravity

    NASA Astrophysics Data System (ADS)

    Dunajski, Maciej; Tod, Paul

    2014-10-01

    We find necessary and sufficient conditions for a Riemannian four-dimensional manifold ( M, g) with anti-self-dual Weyl tensor to be locally conformal to a Ricci-flat manifold. These conditions are expressed as the vanishing of scalar and tensor conformal invariants. The invariants obstruct the existence of parallel sections of a certain connection on a complex rank-four vector bundle over M. They provide a natural generalisation of the Bach tensor which vanishes identically for anti-self-dual conformal structures. We use the obstructions to demonstrate that LeBrun's anti-self-dual metrics on connected sums of s are not conformally Ricci-flat on any open set. We analyze both Riemannian and neutral signature metrics. In the latter case we find all anti-self-dual metrics with a parallel real spinor which are locally conformal to Einstein metrics with non-zero cosmological constant. These metrics admit a hyper-surface orthogonal null Killing vector and thus give rise to projective structures on the space of β-surfaces.

  1. 14 CFR 21.53 - Statement of conformity.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Statement of conformity. 21.53 Section 21... CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS Type Certificates § 21.53 Statement of conformity. Link to an... conformity (FAA Form 317) to the Administrator for each aircraft engine and propeller presented to...

  2. 14 CFR 21.130 - Statement of conformity.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Statement of conformity. 21.130 Section 21... conformity. Each holder or licensee of a type certificate only, for a product manufactured in the United... Administrator a statement of conformity (FAA Form 317). This statement must be signed by an authorized...

  3. 14 CFR 21.130 - Statement of conformity.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Statement of conformity. 21.130 Section 21... conformity. Link to an amendment published at 74 FR 53387, October 16, 2009. Link to an amendment published... the Administrator a statement of conformity (FAA Form 317). This statement must be signed by...

  4. 14 CFR 21.53 - Statement of conformity.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Statement of conformity. 21.53 Section 21... CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS Type Certificates § 21.53 Statement of conformity. Link to an..., 2010. (a) Each applicant must submit a statement of conformity (FAA Form 317) to the Administrator...

  5. Galilean conformal mechanics from nonlinear realizations

    SciTech Connect

    Fedoruk, Sergey; Ivanov, Evgeny; Lukierski, Jerzy

    2011-04-15

    We apply the nonlinear realizations method for constructing new Galilean conformal mechanics models. Our starting point is the Galilean conformal algebra which is a nonrelativistic contraction of its relativistic counterpart. We calculate Maurer-Cartan one-forms, examine various choices of the relevant coset spaces, and consider the geometric inverse Higgs-type constraints which reduce the number of the independent coset parameters and, in some cases, provide dynamical equations. New Galilean conformally invariant actions are derived in arbitrary space-time dimension D=d+1 (no central charges), as well as in the special dimension D=2+1 with one exotic central charge. We obtain new classical mechanics models which extend the standard (D=0+1) conformal mechanics in the presence of d nonvanishing space dimensions.

  6. Logarithmic conformal field theory: beyond an introduction

    NASA Astrophysics Data System (ADS)

    Creutzig, Thomas; Ridout, David

    2013-12-01

    This article aims to review a selection of central topics and examples in logarithmic conformal field theory. It begins with the remarkable observation of Cardy that the horizontal crossing probability of critical percolation may be computed analytically within the formalism of boundary conformal field theory. Cardy’s derivation relies on certain implicit assumptions which are shown to lead inexorably to indecomposable modules and logarithmic singularities in correlators. For this, a short introduction to the fusion algorithm of Nahm, Gaberdiel and Kausch is provided. While the percolation logarithmic conformal field theory is still not completely understood, there are several examples for which the formalism familiar from rational conformal field theory, including bulk partition functions, correlation functions, modular transformations, fusion rules and the Verlinde formula, has been successfully generalized. This is illustrated for three examples: the singlet model \\mathfrak {M} (1,2), related to the triplet model \\mathfrak {W} (1,2), symplectic fermions and the fermionic bc ghost system; the fractional level Wess-Zumino-Witten model based on \\widehat{\\mathfrak {sl}} \\left( 2 \\right) at k=-\\frac{1}{2}, related to the bosonic βγ ghost system; and the Wess-Zumino-Witten model for the Lie supergroup \\mathsf {GL} \\left( 1 {\\mid} 1 \\right), related to \\mathsf {SL} \\left( 2 {\\mid} 1 \\right) at k=-\\frac{1}{2} and 1, the Bershadsky-Polyakov algebra W_3^{(2)} and the Feigin-Semikhatov algebras W_n^{(2)}. These examples have been chosen because they represent the most accessible, and most useful, members of the three best-understood families of logarithmic conformal field theories. The logarithmic minimal models \\mathfrak {W} (q,p), the fractional level Wess-Zumino-Witten models, and the Wess-Zumino-Witten models on Lie supergroups (excluding \\mathsf {OSP} \\left( 1 {\\mid} 2n \\right)). In this review, the emphasis lies on the representation theory

  7. Conformational analysis of oligosaccharides and polysaccharides using molecular dynamics simulations.

    PubMed

    Frank, Martin

    2015-01-01

    Complex carbohydrates usually have a large number of rotatable bonds and consequently a large number of theoretically possible conformations can be generated (combinatorial explosion). The application of systematic search methods for conformational analysis of carbohydrates is therefore limited to disaccharides and trisaccharides in a routine analysis. An alternative approach is to use Monte-Carlo methods or (high-temperature) molecular dynamics (MD) simulations to explore the conformational space of complex carbohydrates. This chapter describes how to use MD simulation data to perform a conformational analysis (conformational maps, hydrogen bonds) of oligosaccharides and how to build realistic 3D structures of large polysaccharides using Conformational Analysis Tools (CAT).

  8. James Webb Space Telescope (JWST) Integrated Science Instruments Module (ISIM) Electronics Compartment (IEC) Conformal Shields Composite Bond Structure Qualification Test Method

    NASA Technical Reports Server (NTRS)

    Yew, Calinda; Stephens, Matt

    2015-01-01

    The JWST IEC conformal shields are mounted onto a composite frame structure that must undergo qualification testing to satisfy mission assurance requirements. The composite frame segments are bonded together at the joints using epoxy, EA 9394. The development of a test method to verify the integrity of the bonded structure at its operating environment introduces challenges in terms of requirements definition and the attainment of success criteria. Even though protoflight thermal requirements were not achieved, the first attempt in exposing the structure to cryogenic operating conditions in a thermal vacuum environment resulted in approximately 1 bonded joints failure during mechanical pull tests performed at 1.25 times the flight loads. Failure analysis concluded that the failure mode was due to adhesive cracks that formed and propagated along stress concentrated fillets as a result of poor bond squeeze-out control during fabrication. Bond repairs were made and the structures successfully re-tested with an improved LN2 immersion test method to achieve protoflight thermal requirements.

  9. New Interface for Accessing Archived European Space Agency Planetary Science Data, Such as the New Venus Express Atmospheric Drag Experiment Data Set

    NASA Astrophysics Data System (ADS)

    Grotheer, E.; Barbarisi, I.; Rios, C.; Macfarlane, A. J.; Docasal, R.; Arviset, C.; Besse, S.; Heather, D.; Gonzalez, J.; De Marchi, G.; Martinez, S.; Lim, T.; Fraga, D.

    2015-12-01

    All Venus Express (VEX) instruments delivered their data products according to the Planetary Data System version 3 (PDS3) standard, and the atmospheric drag experiment (ADE) data was no exception. The European Space Agency's (ESA) Planetary Science Archive (PSA), which can be accessed at www.rssd.esa.int/PSA, is being upgraded to make PDS4 data available from newer missions such as ExoMars and BepiColombo. Thus, the PSA development team has been working to ensure that the legacy PDS3 data will be accessible via the new interface as well. We will preview some of the new methods of accessing legacy VEX data via the new interface, with a focus being placed on the ADE data set. We will show how the ADE data can be accessed using Geographic Information Systems (GIS) and our plans for making this and other data sets compatible with the Virtual European Solar and Planetary Access (VESPA) project for creating a virtual observatory. From February 2010 through March 2014, ESA's Venus Express mission conducted 11 ADE campaigns. During these observation campaigns, VEX's pericenter was in the range of 165 to 190 km, while the spacecraft was near Venus' North pole, and the entire spacecraft was used to make in situ measurements of the atmospheric density. This was done by rotating the solar panels in a manner that somewhat resembles a windmill. Also, VEX 's attitude and orbit control system was tasked with maintaining the spacecraft in a 3-axis stabilized mode during these pericenter passes. The torques that the reaction wheels had to exert to maintain this attitude were then analyzed to yield density readings.

  10. SPRAY FOAM IN ACCESSIBLE SPACES:BEST PRACTICES AND CASE STUDIES FOR RETROFIT IN MIXED-HUMID CLIMATE

    SciTech Connect

    Christian, Jeffrey E; Gant, Kathy

    2013-12-01

    Heating and cooling the house is one of the homeowners major expenses. Reducing these costs, saving energy, and creating a healthier, more comfortable indoor environment are good reasons to consider improving the building thermal envelope. Improvements usually consider increasing the amount of insulation, reducing the infiltration of outside air, and controlling moisture in existing buildings. This report describes the use of spray foam materials to insulate, seal, and control moisture. This discussion is limited to treating areas that are accessible. What is accessible, however, can vary depending on the type of renovation. If the building has been gutted or exterior surfaces removed, there are more options. This report will look at areas to consider for spray foam application and discuss the types of spray foams available and their uses. A number of case studies are presented to show the effectiveness of this retrofit in existing houses based on performance data.

  11. Web Accessibility and Guidelines

    NASA Astrophysics Data System (ADS)

    Harper, Simon; Yesilada, Yeliz

    Access to, and movement around, complex online environments, of which the World Wide Web (Web) is the most popular example, has long been considered an important and major issue in the Web design and usability field. The commonly used slang phrase ‘surfing the Web’ implies rapid and free access, pointing to its importance among designers and users alike. It has also been long established that this potentially complex and difficult access is further complicated, and becomes neither rapid nor free, if the user is disabled. There are millions of people who have disabilities that affect their use of the Web. Web accessibility aims to help these people to perceive, understand, navigate, and interact with, as well as contribute to, the Web, and thereby the society in general. This accessibility is, in part, facilitated by the Web Content Accessibility Guidelines (WCAG) currently moving from version one to two. These guidelines are intended to encourage designers to make sure their sites conform to specifications, and in that conformance enable the assistive technologies of disabled users to better interact with the page content. In this way, it was hoped that accessibility could be supported. While this is in part true, guidelines do not solve all problems and the new WCAG version two guidelines are surrounded by controversy and intrigue. This chapter aims to establish the published literature related to Web accessibility and Web accessibility guidelines, and discuss limitations of the current guidelines and future directions.

  12. Basic Research Investigations into Multimode Laser and EM Launchers for Affordable Rapid Access to Space (Volumes 1 and 2)

    DTIC Science & Technology

    2010-08-31

    station. Right: Lightcraft vehicle on launch pad. Palm et al. (2009...serviced by space-based power-beaming station. Right: Lightcraft vehicle on launch pad. Palm et al. (2009) 1.1 Worldwide State-of-the-Art on Beamed...example, this asymmetry favors P8, the tilted LSD kernel could momentarily drive pressures higher at P8, than reach P9, well before transition to an

  13. Programmable Ultra Lightweight System Adaptable Radio (PULSAR) Low Cost Telemetry - Access from Space Advanced Technologies or Down the Middle

    NASA Technical Reports Server (NTRS)

    Sims. Herb; Varnavas, Kosta; Eberly, Eric

    2013-01-01

    Software Defined Radio (SDR) technology has been proven in the commercial sector since the early 1990's. Today's rapid advancement in mobile telephone reliability and power management capabilities exemplifies the effectiveness of the SDR technology for the modern communications market. In contrast, presently qualified satellite transponder applications were developed during the early 1960's space program. Programmable Ultra Lightweight System Adaptable Radio (PULSAR, NASA-MSFC SDR) technology revolutionizes satellite transponder technology by increasing data through-put capability by, at least, an order of magnitude. PULSAR leverages existing Marshall Space Flight Center SDR designs and commercially enhanced capabilities to provide a path to a radiation tolerant SDR transponder. These innovations will (1) reduce the cost of NASA Low Earth Orbit (LEO) and Deep Space transponders, (2) decrease power requirements, and (3) a commensurate volume reduction. Also, PULSAR increases flexibility to implement multiple transponder types by utilizing the same hardware with altered logic - no analog hardware change is required - all of which can be accomplished in orbit. This provides high capability, low cost, transponders to programs of all sizes. The final project outcome would be the introduction of a Technology Readiness Level (TRL) 7 low-cost CubeSat to SmallSat telemetry system into the NASA Portfolio.

  14. On useful conformal tranformations in general relativity

    NASA Astrophysics Data System (ADS)

    Carneiro, D. F.; Freiras, E. A.; Gonçalves, B.; de Lima, A. G.; Shapiro, I.

    2004-12-01

    Local conformal transformations are known as a useful tool in various applications of the gravitational theory, especially in cosmology. We describe some new aspects of these transformations, in particular using them for derivation of Einstein equations for the cosmological and Schwarzschild metrics. Furthermore, the conformal transformation is applied for the dimensional reduction of the Gauss-Bonnet topological invariant in $d=4$ to the spaces of lower dimensions.

  15. The Near-Earth Object Human Space Flight Accessible Targets Study (NHATS) List of Near-Earth Asteroids: Identifying Potential Targets for Future Exploration

    NASA Technical Reports Server (NTRS)

    Abell, Paul A.; Barbee, B. W.; Mink, R. G.; Alberding, C. M.; Adamo, D. R.; Mazanek, D. D.; Johnson, L. N.; Yeomans, D. K.; Chodas, P. W.; Chamberlin, A. B.; Benner, L. A. M.; Drake, B. G.; Friedensen, V. P.

    2012-01-01

    Over the past several years, much attention has been focused on the human exploration of near-Earth asteroids (NEAs). Two independent NASA studies examined the feasibility of sending piloted missions to NEAs [1, 2], and in 2009, the Augustine Commission identified NEAs as high profile destinations for human exploration missions beyond the Earth-Moon system [3]. More recently the current U.S. presidential administration directed NASA to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010 [4]. Detailed planning for such deep space exploration missions and identifying potential NEAs as targets for human spaceflight requires selecting objects from the ever growing list of newly discovered NEAs. Hence NASA developed and implemented the Near-Earth Object (NEO) Human Space Flight (HSF) Accessible Target Study (NHATS), which identifies potential candidate objects on the basis of defined dynamical trajectory performance constraints.

  16. High Speed, Low Cost Telemetry Access from Space Development Update on Programmable Ultra Lightweight System Adaptable Radio (PULSAR)

    NASA Technical Reports Server (NTRS)

    Simms, William Herbert, III; Varnavas, Kosta; Eberly, Eric

    2014-01-01

    Software Defined Radio (SDR) technology has been proven in the commercial sector since the early 1990's. Today's rapid advancement in mobile telephone reliability and power management capabilities exemplifies the effectiveness of the SDR technology for the modern communications market. In contrast, the foundations of transponder technology presently qualified for satellite applications were developed during the early space program of the 1960's. Conventional transponders are built to a specific platform and must be redesigned for every new bus while the SDR is adaptive in nature and can fit numerous applications with no hardware modifications. A SDR uses a minimum amount of analog / Radio Frequency (RF) components to up/down-convert the RF signal to/from a digital format. Once the signal is digitized, all processing is performed using hardware or software logic. Typical SDR digital processes include; filtering, modulation, up/down converting and demodulation. NASA Marshall Space Flight Center (MSFC) Programmable Ultra Lightweight System Adaptable Radio (PULSAR) leverages existing MSFC SDR designs and commercial sector enhanced capabilities to provide a path to a radiation tolerant SDR transponder. These innovations (1) reduce the cost of NASA Low Earth Orbit (LEO) and Deep Space standard transponders, (2) decrease power requirements, and (3) commensurately reduce volume. A second pay-off is the increased SDR flexibility by allowing the same hardware to implement multiple transponder types simply by altering hardware logic - no change of hardware is required - all of which will ultimately be accomplished in orbit. Development of SDR technology for space applications will provide a highly capable, low cost transponder to programs of all sizes. The MSFC PULSAR Project results in a Technology Readiness Level (TRL) 7 low-cost telemetry system available to Smallsat and CubeSat missions, as well as other platforms. This paper documents the continued development and

  17. Anomalies, conformal manifolds, and spheres

    DOE PAGES

    Gomis, Jaume; Hsin, Po-Shen; Komargodski, Zohar; ...

    2016-03-04

    The two-point function of exactly marginal operators leads to a universal contribution to the trace anomaly in even dimensions. We study aspects of this trace anomaly, emphasizing its interpretation as a sigma model, whose target space $M$ is the space of conformal field theories (a.k.a. the conformal manifold). When the underlying quantum field theory is supersymmetric, this sigma model has to be appropriately supersymmetrized. As examples, we consider in some detail $N$ = (2; 2) and $N$ = (0; 2) supersymmetric theories in d = 2 and $N$ = 2 supersymmetric theories in d = 4. This reasoning leads tomore » new information about the conformal manifolds of these theories, for example, we show that the manifold is K ahler-Hodge and we further argue that it has vanishing K ahler class. For $N$ = (2; 2) theories in d = 2 and N = 2 theories in d = 4 we also show that the relation between the sphere partition function and the K ahler potential of $M$ follows immediately from the appropriate sigma models that we construct. Ultimately, along the way we find several examples of potential trace anomalies that obey the Wess-Zumino consistency conditions, but can be ruled out by a more detailed analysis.« less

  18. Anomalies, conformal manifolds, and spheres

    SciTech Connect

    Gomis, Jaume; Hsin, Po-Shen; Komargodski, Zohar; Schwimmer, Adam; Seiberg, Nathan; Theisen, Stefan

    2016-03-04

    The two-point function of exactly marginal operators leads to a universal contribution to the trace anomaly in even dimensions. We study aspects of this trace anomaly, emphasizing its interpretation as a sigma model, whose target space $M$ is the space of conformal field theories (a.k.a. the conformal manifold). When the underlying quantum field theory is supersymmetric, this sigma model has to be appropriately supersymmetrized. As examples, we consider in some detail $N$ = (2; 2) and $N$ = (0; 2) supersymmetric theories in d = 2 and $N$ = 2 supersymmetric theories in d = 4. This reasoning leads to new information about the conformal manifolds of these theories, for example, we show that the manifold is K ahler-Hodge and we further argue that it has vanishing K ahler class. For $N$ = (2; 2) theories in d = 2 and N = 2 theories in d = 4 we also show that the relation between the sphere partition function and the K ahler potential of $M$ follows immediately from the appropriate sigma models that we construct. Ultimately, along the way we find several examples of potential trace anomalies that obey the Wess-Zumino consistency conditions, but can be ruled out by a more detailed analysis.

  19. Conformational analysis of small molecules: NMR and quantum mechanics calculations.

    PubMed

    Tormena, Cláudio F

    2016-08-01

    This review deals with conformational analysis in small organic molecules, and describes the stereoelectronic interactions responsible for conformational stability. Conformational analysis is usually performed using NMR spectroscopy through measurement of coupling constants at room or low temperature in different solvents to determine the populations of conformers in solution. Quantum mechanical calculations are used to address the interactions responsible for conformer stability. The conformational analysis of a large number of small molecules is described, using coupling constant measurements in different solvents and at low temperature, as well as recent applications of through-space and through-hydrogen bond coupling constants JFH as tools for the conformational analysis of fluorinated molecules. Besides NMR parameters, stereoelectronic interactions such as conjugative, hyperconjugative, steric and intramolecular hydrogen bond interactions involved in conformational preferences are discussed.

  20. Optical multidimensional multiple access(O-MDMA): a new concept for free-space laser communication based on photonic mixer devices

    NASA Astrophysics Data System (ADS)

    Hess, Holger; Albrecht, Martin; Grothof, Markus; Hussmann, Stephan; Schwarte, Rudolf

    2004-01-01

    Working on optical distance measurement a new optical correlator was developed at the Institute for Data Processing of the University of Siegen in the last years. The so called Photonic Mixer Device (PMD), to be meant originally for laser ranging systems, offers a lot of advantages for wireless optical data communication like high speed spatial light demodulation up to the GHz range and inherent backlight suppression. This contribution describes the application of such PMDs in a free space interconnect based on the principle of Multi Dimensional Multiple Access (MDMA) and the advantages of this new approach, starting from the MDMA principle and followed by the fundamental functionality of PMDs. After that an Optical MDMA (O-MDMA) demonstrator and first measurement results will be presented.

  1. Earth Science Data Archive and Access at the NASA/Goddard Space Flight Center Distributed Active Archive Center (DAAC)

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory

    1999-01-01

    The Goddard Distributed Active Archive Center (DAAC), as an integral part of the Earth Observing System Data and Information System (EOSDIS), is the official source of data for several important earth remote sensing missions. These include the Sea-viewing Wide-Field-of-view Sensor (SeaWiFS) launched in August 1997, the Tropical Rainfall Measuring Mission (TRMM) launched in November 1997, and the Moderate Resolution Imaging Spectroradiometer (MODIS) scheduled for launch in mid 1999 as part of the EOS AM-1 instrumentation package. The data generated from these missions supports a host of users in the hydrological, land biosphere and oceanographic research and applications communities. The volume and nature of the data present unique challenges to an Earth science data archive and distribution system such as the DAAC. The DAAC system receives, archives and distributes a large number of standard data products on a daily basis, including data files that have been reprocessed with updated calibration data or improved analytical algorithms. A World Wide Web interface is provided allowing interactive data selection and automatic data subscriptions as distribution options. The DAAC also creates customized and value-added data products, which allow additional user flexibility and reduced data volume. Another significant part of our overall mission is to provide ancillary data support services and archive support for worldwide field campaigns designed to validate the results from the various satellite-derived measurements. In addition to direct data services, accompanying documentation, WWW links to related resources, support for EOSDIS data formats, and informed response to inquiries are routinely provided to users. The current GDAAC WWW search and order system is being restructured to provide users with a simplified, hierarchical access to data. Data Browsers have been developed for several data sets to aid users in ordering data. These Browsers allow users to specify

  2. The Conformal Bootstrap

    NASA Astrophysics Data System (ADS)

    Simmons-Duffin, David

    These notes are from courses given at TASI and the Advanced Strings School in summer 2015. Starting from principles of quantum field theory and the assumption of a traceless stress tensor, we develop the basics of conformal field theory, including conformal Ward identities, radial quantization, reection positivity, the operator product expansion, and conformal blocks. We end with an introduction to numerical bootstrap methods, focusing on the 2d and 3d Ising models.

  3. [Food environment and space accessibility evaluation to perform physical activity in 3 socially contrasting neighbourhoods of Buenos Aires city].

    PubMed

    Garipe, Leila Yasmin; Gónzalez, Verónica; Biasizzo, Antonella; Soriano, Jennifer Laila; Perman, Gaston; Giunta, Diego

    2014-01-01

    Due to the environmental influences on health, the goal of this study was to describe and compare the built environment in 3 socially contrasting neighbourhoods of Buenos Aires city.In 2011 a cross-sectional study was conducted in 3 socially contrasting neighbourhoods of Buenos Aires city: Recoleta (upper class), Almagro (middle class) and Constitución (lower class). Grocery stores and food stands were surveyed as well as all suitable spaces to perform physical activity. An analysis was conducted to assess the density of every food outlet per Km2 of each neighbourhood's area and per 10000 inhabitants. 2778 food stores and 149 outdoor physical activity facilities were surveyed. A higher density was observed in Constitución for fast food restaurants (Recoleta 3.6; Almagro 2.4; Constitución 6.7) and food stands (Recoleta 4.2; Almagro 1.2; Constitución 25.7) and a lower density for outdoor physical activity facilities. Population density and area density proved to be analogous. Statistically relevant differences were observed regarding the dimension of each food outlet: grocery stores, fruit stands, pubs, restaurants and food stands, as well as in the number of food stores and outdoor physical activity facilities. The information gathered in this study could be highly useful for public health policies on healthy lifestyles, and could eventually redefine the built environment in order to improve the city's equality regarding outdoor physical activity facilities and food stores.

  4. False security or greater social inclusion? Exploring perceptions of CCTV use in public and private spaces accessed by the homeless.

    PubMed

    Huey, Laura

    2010-03-01

    It has been well documented that owing to the vulnerability inherent in their situation and status, the homeless experience high rates of harassment and criminal victimization. And yet, the question of whether CCTV surveillance of public and private spaces - so frequently viewed by the middle classes as a positive source of potential security - might also be viewed by the homeless in similar ways. Within the present paper, I address this issue by considering the possibility that CCTV might be seen by some homeless men and women as offering: a) a measure of enhanced security for those living in the streets and in shelters, and; b) to the extent that security is conceived of as a social good, the receipt of which marks one as a citizen of the state, a means by which they can be reconstituted as something more than 'lesser citizens'. To test these ideas, I rely on data from interviews conducted with homeless service users, service providers for the homeless, and police personnel in three cities. What is revealed is a mixed set of beliefs as to the relative security and meaning of CCTV.

  5. NASA Affordable Vehicle Avionics (AVA): Common Modular Avionics System for Nano-Launchers Offering Affordable Access to Space

    NASA Technical Reports Server (NTRS)

    Cockrell, James

    2015-01-01

    Small satellites are becoming ever more capable of performing valuable missions for both government and commercial customers. However, currently these satellites can only be launched affordably as secondary payloads. This makes it difficult for the small satellite mission to launch when needed, to the desired orbit, and with acceptable risk. NASA Ames Research Center has developed and tested a prototype low-cost avionics package for space launch vehicles that provides complete GNC functionality in a package smaller than a tissue box with a mass less than 0.84 kg. AVA takes advantage of commercially available, low-cost, mass-produced, miniaturized sensors, filtering their more noisy inertial data with realtime GPS data. The goal of the Advanced Vehicle Avionics project is to produce and flight-verify a common suite of avionics and software that deliver affordable, capable GNC and telemetry avionics with application to multiple nano-launch vehicles at 1 the cost of current state-of-the-art avionics.

  6. [Dosimetric evaluation of conformal radiotherapy: conformity factor].

    PubMed

    Oozeer, R; Chauvet, B; Garcia, R; Berger, C; Felix-Faure, C; Reboul, F

    2000-01-01

    The aim of three-dimensional conformal therapy (3DCRT) is to treat the Planning Target Volume (PTV) to the prescribed dose while reducing doses to normal tissues and critical structures, in order to increase local control and reduce toxicity. The evaluation tools used for optimizing treatment techniques are three-dimensional visualization of dose distributions, dose-volume histograms, tumor control probabilities (TCP) and normal tissue complication probabilities (NTCP). These tools, however, do not fully quantify the conformity of dose distributions to the PTV. Specific tools were introduced to measure this conformity for a given dose level. We have extended those definitions to different dose levels, using a conformity index (CI). CI is based on the relative volumes of PTV and outside the PTV receiving more than a given dose. This parameter has been evaluated by a clinical study including 82 patients treated for lung cancer and 82 patients treated for prostate cancer. The CI was low for lung dosimetric studies (0.35 at the prescribed dose 66 Gy) due to build-up around the GTV and to spinal cord sparing. For prostate dosimetric studies, the CI was higher (0.57 at the prescribed dose 70 Gy). The CI has been used to compare treatment plans for lung 3DCRT (2 vs 3 beams) and prostate 3DCRT (4 vs 7 beams). The variation of CI with dose can be used to optimize dose prescription.

  7. Conformal differential invariants

    NASA Astrophysics Data System (ADS)

    Kruglikov, Boris

    2017-03-01

    We compute the Hilbert polynomial and the Poincaré function counting the number of fixed jet-order differential invariants of conformal metric structures modulo local diffeomorphisms, and we describe the field of rational differential invariants separating generic orbits of the diffeomorphism pseudogroup action. This resolves the local recognition problem for conformal structures.

  8. Conformations of Substituted Ethanes.

    ERIC Educational Resources Information Center

    Kingsbury, Charles A.

    1979-01-01

    Reviews state-of-the-art of conformational analysis and factors which affect it. Emphasizes sp-3 hybridized acrylic molecules. Provides examples on the importance of certain factors in determining conformation. Purpose, is to provide examples for examination questions. (Author/SA)

  9. Conformational properties of oxazoline-amino acids

    NASA Astrophysics Data System (ADS)

    Staś, Monika; Broda, Małgorzata A.; Siodłak, Dawid

    2016-04-01

    Oxazoline-amino acids (Xaa-Ozn) occur in natural peptides of potentially important bioactivity. The conformations of the model compounds: Ac-(S)-Ala-Ozn(4R-Me), Ac-(S)-Ala-Ozn(4S-Me), and (gauche+, gauche-, anti) Ac-(S)-Val-Ozn(4R-Me) were studied at meta-hybrid M06-2X/6-311++G(d,p) method including solvent effect. Boc-L-Ala-L-Ozn-4-COOMe and Boc-L-Val-L-Ozn-4-COOMe were synthesized and studied by FT-IR and NMR-NOE methods. The conformations in crystal state were gathered from the Cambridge Structural Data Base. The main conformational feature of the oxazoline amino acids is the conformation β2 (ϕ,ψ ∼ -161°, -6°), which predominates in weakly polar environment and still is accessible in polar surrounding. The changes of the conformational preferences towards the conformations αR (ϕ,ψ ∼ -70°, -15°) and then β (ϕ,ψ ∼ -57°, -155°) are observed with increase of the environment polarity.

  10. New potentials for conformal mechanics

    NASA Astrophysics Data System (ADS)

    Papadopoulos, G.

    2013-04-01

    We find under some mild assumptions that the most general potential of one-dimensional conformal systems with time-independent couplings is expressed as V = V0 + V1, where V0 is a homogeneous function with respect to a homothetic motion in configuration space and V1 is determined from an equation with source a homothetic potential. Such systems admit at most an SL(2,{R}) conformal symmetry which, depending on the couplings, is embedded in {Diff}({R}) in three different ways. In one case, SL(2,{R}) is also embedded in Diff(S1). Examples of such models include those with potential V = αx2 + βx-2 for arbitrary couplings α and β, the Calogero models with harmonic oscillator couplings and nonlinear models with suitable metrics and potentials. In addition, we give the conditions on the couplings for a class of gauge theories to admit a SL(2,{R}) conformal symmetry. We present examples of such systems with general gauge groups and global symmetries that include the isometries of AdS2 × S3 and AdS2 × S3 × S3 which arise as backgrounds in AdS2/CFT1.

  11. EC declaration of conformity.

    PubMed

    Donawa, M E

    1996-05-01

    The CE-marking procedure requires that manufacturers draw up a written declaration of conformity before placing their products on the market. However, some companies do not realize that this is a requirement for all devices. Also, there is no detailed information concerning the contents and format of the EC declaration of conformity in the medical device Directives or in EC guidance documentation. This article will discuss some important aspects of the EC declaration of conformity and some of the guidance that is available on its contents and format.

  12. FAST Conformational Searches by Balancing Exploration/Exploitation Trade-Offs.

    PubMed

    Zimmerman, Maxwell I; Bowman, Gregory R

    2015-12-08

    Molecular dynamics simulations are a powerful means of understanding conformational changes. However, it is still difficult to simulate biologically relevant time scales without the use of specialized supercomputers. Here, we introduce a goal-oriented sampling method, called fluctuation amplification of specific traits (FAST), for extending the capabilities of commodity hardware. This algorithm rapidly searches conformational space for structures with desired properties by balancing trade-offs between focused searches around promising solutions (exploitation) and trying novel solutions (exploration). FAST was inspired by the hypothesis that many physical properties have an overall gradient in conformational space, akin to the energetic gradients that are known to guide proteins to their folded states. For example, we expect that transitioning from a conformation with a small solvent-accessible surface area to one with a large surface area will require passing through a series of conformations with steadily increasing surface areas. We demonstrate that such gradients are common through retrospective analysis of existing Markov state models (MSMs). Then we design the FAST algorithm to exploit these gradients to find structures with desired properties by (1) recognizing and amplifying structural fluctuations along gradients that optimize a selected physical property whenever possible, (2) overcoming barriers that interrupt these overall gradients, and (3) rerouting to discover alternative paths when faced with insurmountable barriers. To test FAST, we compare its performance to other methods for three common types of problems: (1) identifying unexpected binding pockets, (2) discovering the preferred paths between specific structures, and (3) folding proteins. Our conservative estimate is that FAST outperforms conventional simulations and an adaptive sampling algorithm by at least an order of magnitude. Furthermore, FAST yields both the proper thermodynamics and

  13. Animal culture: chimpanzee conformity?

    PubMed

    van Schaik, Carel P

    2012-05-22

    Culture-like phenomena in wild animals have received much attention, but how good is the evidence and how similar are they to human culture? New data on chimpanzees suggest their culture may even have an element of conformity.

  14. ACCESS Pointing Control System

    NASA Technical Reports Server (NTRS)

    Brugarolas, Paul; Alexander, James; Trauger, John; Moody, Dwight; Egerman, Robert; Vallone, Phillip; Elias, Jason; Hejal, Reem; Camelo, Vanessa; Bronowicki, Allen; O'Connor, David; Partrick, Richard; Orzechowski, Pawel; Spitter, Connie; Lillie, Chuck

    2010-01-01

    ACCESS (Actively-Corrected Coronograph for Exoplanet System Studies) was one of four medium-class exoplanet concepts selected for the NASA Astrophysics Strategic Mission Concept Study (ASMCS) program in 2008/2009. The ACCESS study evaluated four major coronograph concepts under a common space observatory. This paper describes the high precision pointing control system (PCS) baselined for this observatory.

  15. Granting Each Equal Access.

    ERIC Educational Resources Information Center

    Walling, Linda Lucas

    1992-01-01

    Summarizes federal legislation regarding equal access for students with disabilities and discusses environmental barriers to accessibility in the library media center. Solutions to these design problems are suggested in the following areas: material formats and space requirements; the physical setting, including furniture, floor coverings,…

  16. Conformation analysis of intermediates of analogues of Tamoxifen

    NASA Astrophysics Data System (ADS)

    Kapiller-Dezsőfi, Rita; Németh, Gábor; Lax, Györgyi; Simig, Gyula; Sohár, Pál

    1998-01-01

    The configuration and the conformation of two trifluoromethyl-triaryl-ethane diastereomer pairs and of some sole isomers were determined using the through-space spin-spin coupling between fluorine atoms and the hydrogen of the hydroxyl group. The molecule-mechanical calculations support the results of the conformation-analysis based on the NMR data.

  17. A disulfide-stabilized conformer of methionine synthase reveals an unexpected role for the histidine ligand of the cobalamin cofactor

    SciTech Connect

    Datta, Supratim; Koutmos, Markos; Pattridge, Katherine A.; Ludwig, Martha L.; Matthews, Rowena G.

    2008-07-08

    B{sub 12}-dependent methionine synthase (MetH) from Escherichia coli is a large modular protein that is alternately methylated by methyltetrahydrofolate to form methylcobalamin and demethylated by homocysteine to form cob(I)alamin. Major domain rearrangements are required to allow cobalamin to react with three different substrates: homocysteine, methyltetrahydrofolate, and S-adenosyl-l-methionine (AdoMet). These same rearrangements appear to preclude crystallization of the wild-type enzyme. Disulfide cross-linking was used to lock a C-terminal fragment of the enzyme into a unique conformation. Cysteine point mutations were introduced at Ile-690 and Gly-743. These cysteine residues span the cap and the cobalamin-binding module and form a cross-link that reduces the conformational space accessed by the enzyme, facilitating protein crystallization. Here, we describe an x-ray structure of the mutant fragment in the reactivation conformation; this conformation enables the transfer of a methyl group from AdoMet to the cobalamin cofactor. In the structure, the axial ligand to the cobalamin, His-759, dissociates from the cobalamin and forms intermodular contacts with residues in the AdoMet-binding module. This unanticipated intermodular interaction is expected to play a major role in controlling the distribution of conformers required for the catalytic and the reactivation cycles of the enzyme.

  18. Conformations of an adenine bulge in a DNA octamer and its influence on DNA structure from molecular dynamics simulations.

    PubMed Central

    Feig, M; Zacharias, M; Pettitt, B M

    2001-01-01

    Molecular dynamics simulations have been applied to the DNA octamer d(GCGCA-GAAC). d(GTTCGCGC), which has an adenine bulge at the center to determine the pathway for interconversion between the stacked and extended forms. These forms are known to be important in the molecular recognition of bulges. From a total of ~35 ns of simulation time with the most recent CHARMM27 force field a variety of distinct conformations and subconformations are found. Stacked and fully looped-out forms are in excellent agreement with experimental data from NMR and x-ray crystallography. Furthermore, in a number of conformations the bulge base associates with the minor groove to varying degrees. Transitions between many of the conformations are observed in the simulations and used to propose a complete transition pathway between the stacked and fully extended conformations. The effect on the surrounding DNA sequence is investigated and biological implications of the accessible conformational space and the suggested transition pathway are discussed, in particular for the interaction of the MS2 replicase operator RNA with its coat protein. PMID:11423420

  19. Logarithmic conformal field theory

    NASA Astrophysics Data System (ADS)

    Gainutdinov, Azat; Ridout, David; Runkel, Ingo

    2013-12-01

    Conformal field theory (CFT) has proven to be one of the richest and deepest subjects of modern theoretical and mathematical physics research, especially as regards statistical mechanics and string theory. It has also stimulated an enormous amount of activity in mathematics, shaping and building bridges between seemingly disparate fields through the study of vertex operator algebras, a (partial) axiomatisation of a chiral CFT. One can add to this that the successes of CFT, particularly when applied to statistical lattice models, have also served as an inspiration for mathematicians to develop entirely new fields: the Schramm-Loewner evolution and Smirnov's discrete complex analysis being notable examples. When the energy operator fails to be diagonalisable on the quantum state space, the CFT is said to be logarithmic. Consequently, a logarithmic CFT is one whose quantum space of states is constructed from a collection of representations which includes reducible but indecomposable ones. This qualifier arises because of the consequence that certain correlation functions will possess logarithmic singularities, something that contrasts with the familiar case of power law singularities. While such logarithmic singularities and reducible representations were noted by Rozansky and Saleur in their study of the U (1|1) Wess-Zumino-Witten model in 1992, the link between the non-diagonalisability of the energy operator and logarithmic singularities in correlators is usually ascribed to Gurarie's 1993 article (his paper also contains the first usage of the term 'logarithmic conformal field theory'). The class of CFTs that were under control at this time was quite small. In particular, an enormous amount of work from the statistical mechanics and string theory communities had produced a fairly detailed understanding of the (so-called) rational CFTs. However, physicists from both camps were well aware that applications from many diverse fields required significantly more

  20. Protein Conformational Populations and Functionally Relevant Sub-states

    SciTech Connect

    Agarwal, Pratul K; Burger, Virginia; Savol, Andrej; Ramanathan, Arvind; Chennubhotla, Chakra

    2013-01-01

    Functioning proteins do not remain fixed in a unique structure, but instead they sample a range of conformations facilitated by motions within the protein. Even in the native state, a protein exists as a collection of interconverting conformations driven by thermodynamic fluctuations. Motions on the fast time scale allow a protein to sample conformations in the nearby area of its conformational landscape, while motions on slower time scales give it access to conformations in distal areas of the landscape. Emerging evidence indicates that protein landscapes contain conformational substates with dynamic and structural features that support the designated function of the protein. Nuclear magnetic resonance (NMR) experiments provide information about conformational ensembles of proteins. X-ray crystallography allows researchers to identify the most populated states along the landscape, and computational simulations give atom-level information about the conformational substates of different proteins. This ability to characterize and obtain quantitative information about the conformational substates and the populations of proteins within them is allowing researchers to better understand the relationship between protein structure and dynamics and the mechanisms of protein function. In this Account, we discuss recent developments and challenges in the characterization of functionally relevant conformational populations and substates of proteins. In some enzymes, the sampling of functionally relevant conformational substates is connected to promoting the overall mechanism of catalysis. For example, the conformational landscape of the enzyme dihydrofolate reductase has multiple substates, which facilitate the binding and the release of the cofactor and substrate and catalyze the hydride transfer. For the enzyme cyclophilin A, computational simulations reveal that the long time scale conformational fluctuations enable the enzyme to access conformational substates that allow

  1. Conformation of yeast 18S rRNA. Direct chemical probing of the 5' domain in ribosomal subunits and in deproteinized RNA by reverse transcriptase mapping of dimethyl sulfate-accessible.

    PubMed Central

    Lempereur, L; Nicoloso, M; Riehl, N; Ehresmann, C; Ehresmann, B; Bachellerie, J P

    1985-01-01

    The structure of the 5' domain of yeast 18S rRNA has been probed by dimethyl sulfate (DMS), either in "native" deproteinized molecules or in the 40S ribosomal subunits. DMS-reacted RNA has been used as a template for reverse transcription and a large number of reactive sites, corresponding to all types of bases have been mapped by a primer extension procedure, taking advantage of blocks in cDNA elongation immediately upstream from bases methylated at atom positions involved in the base-pair recognition of the template. Since the same atom positions are protected from DMS in base-paired nucleotides, the secondary structure status of each nucleotide can be directly assessed in this procedure, thus allowing to evaluate the potential contribution of proteins in modulating subunit rRNA conformation. While the DMS probing of deproteinized rRNA confirms a number of helical stems predicted by phylogenetic comparisons, it is remarkable that a few additional base-pairings, while proven by the comparative analysis, appear to require the presence of the bound ribosomal subunit proteins to be stabilized. Images PMID:2417197

  2. Bianchi type-I models with conformally invariant scalar field

    SciTech Connect

    Accioly, A.J.; Vaidya, A.N.; Som, M.M.

    1983-05-15

    The solutions of the Einstein equations with the trace-free energy-momentum tensor of conformally invariant scalar field as source are obtained in a spatially homogeneous anisotropic space-time. Some interesting features of the solutions are discussed.

  3. Conformally flat Lorentzian manifolds with special holonomy groups

    SciTech Connect

    Galaev, A S

    2013-09-30

    We obtain a local classification of conformally flat Lorentzian manifolds with special holonomy groups. The corresponding local metrics are certain extensions of Riemannian spaces of constant sectional curvature to Walker metrics. Bibliography: 28 titles.

  4. Enhancing Scientific Collaboration, Transparency, and Public Access: Utilizing the Second Life Platform to Convene a Scientific Conference in 3-D Virtual Space

    NASA Astrophysics Data System (ADS)

    McGee, B. W.

    2006-12-01

    Recent studies reveal a general mistrust of science as well as a distorted perception of the scientific method by the public at-large. Concurrently, the number of science undergraduate and graduate students is in decline. By taking advantage of emergent technologies not only for direct public outreach but also to enhance public accessibility to the science process, it may be possible to both begin a reversal of popular scientific misconceptions and to engage a new generation of scientists. The Second Life platform is a 3-D virtual world produced and operated by Linden Research, Inc., a privately owned company instituted to develop new forms of immersive entertainment. Free and downloadable to the public, Second Life offers an imbedded physics engine, streaming audio and video capability, and unlike other "multiplayer" software, the objects and inhabitants of Second Life are entirely designed and created by its users, providing an open-ended experience without the structure of a traditional video game. Already, educational institutions, virtual museums, and real-world businesses are utilizing Second Life for teleconferencing, pre-visualization, and distance education, as well as to conduct traditional business. However, the untapped potential of Second Life lies in its versatility, where the limitations of traditional scientific meeting venues do not exist, and attendees need not be restricted by prohibitive travel costs. It will be shown that the Second Life system enables scientific authors and presenters at a "virtual conference" to display figures and images at full resolution, employ audio-visual content typically not available to conference organizers, and to perform demonstrations or premier three-dimensional renderings of objects, processes, or information. An enhanced presentation like those possible with Second Life would be more engaging to non- scientists, and such an event would be accessible to the general users of Second Life, who could have an

  5. Pilot Non-Conformance to Alerting System Commands

    NASA Technical Reports Server (NTRS)

    Pritchett, Amy R.; Hansman, R. John

    1997-01-01

    Instances of pilot non-conformance to alerting system commands have been identified in previous studies. Pilot non-conformance changes the final behavior of the system, and therefore may reduce actual performance from that anticipated. A simulator study has examined pilot non-conformance, using the task of collision avoidance during closely spaced parallel approaches as a case study. Consonance between the display and the alerting system was found to significantly improve subject agreement with automatic alerts. Based on these results, a more general discussion of the factors involved in pilot conformance is given, and design guidelines for alerting systems are given.

  6. Isoperimetric inequality on conformally hyperbolic manifolds

    SciTech Connect

    Kesel'man, V M

    2003-04-30

    It is shown that on an arbitrary non-compact Riemannian manifold of conformally hyperbolic type the isoperimetric inequality can be taken by a conformal change of the metric to the same canonical linear form as in the case of the standard hyperbolic Lobachevskii space. Both the absolute isoperimetric inequality and the relative one (for manifolds with boundary) are obtained. This work develops the results and methods of a joint paper with Zorich, in which the absolute isoperimetric inequality was obtained under a certain additional condition; the resulting statements are definitive in a certain sense.

  7. Isoperimetric inequality on conformally hyperbolic manifolds

    NASA Astrophysics Data System (ADS)

    Kesel'man, V. M.

    2003-04-01

    It is shown that on an arbitrary non-compact Riemannian manifold of conformally hyperbolic type the isoperimetric inequality can be taken by a conformal change of the metric to the same canonical linear form as in the case of the standard hyperbolic Lobachevskii space. Both the absolute isoperimetric inequality and the relative one (for manifolds with boundary) are obtained.This work develops the results and methods of a joint paper with Zorich, in which the absolute isoperimetric inequality was obtained under a certain additional condition; the resulting statements are definitive in a certain sense.

  8. Comments on conformal Killing vector fields and quantum field theory

    SciTech Connect

    Brown, M.R.; Ottewill, A.C.; Siklos, S.T.C.

    1982-10-15

    We give a comprehensive analysis of those vacuums for flat and conformally flat space-times which can be defined by timelike, hypersurface-orthogonal, conformal Killing vector fields. We obtain formulas for the difference in stress-energy density between any two such states and display the correspondence with the renormalized stress tensors. A brief discussion is given of the relevance of these results to quantum-mechanical measurements made by noninertial observers moving through flat space.

  9. Conformational kinetics reveals affinities of protein conformational states.

    PubMed

    Daniels, Kyle G; Suo, Yang; Oas, Terrence G

    2015-07-28

    Most biological reactions rely on interplay between binding and changes in both macromolecular structure and dynamics. Practical understanding of this interplay requires detection of critical intermediates and determination of their binding and conformational characteristics. However, many of these species are only transiently present and they have often been overlooked in mechanistic studies of reactions that couple binding to conformational change. We monitored the kinetics of ligand-induced conformational changes in a small protein using six different ligands. We analyzed the kinetic data to simultaneously determine both binding affinities for the conformational states and the rate constants of conformational change. The approach we used is sufficiently robust to determine the affinities of three conformational states and detect even modest differences in the protein's affinities for relatively similar ligands. Ligand binding favors higher-affinity conformational states by increasing forward conformational rate constants and/or decreasing reverse conformational rate constants. The amounts by which forward rate constants increase and reverse rate constants decrease are proportional to the ratio of affinities of the conformational states. We also show that both the affinity ratio and another parameter, which quantifies the changes in conformational rate constants upon ligand binding, are strong determinants of the mechanism (conformational selection and/or induced fit) of molecular recognition. Our results highlight the utility of analyzing the kinetics of conformational changes to determine affinities that cannot be determined from equilibrium experiments. Most importantly, they demonstrate an inextricable link between conformational dynamics and the binding affinities of conformational states.

  10. Conformers of Gaseous Serine.

    PubMed

    He, Kedan; Allen, Wesley D

    2016-08-09

    The myriad conformers of the neutral form of natural amino acid serine (Ser) have been investigated by systematic computations with reliable electronic wave function methods. A total of 85 unique conformers were located using the MP2/cc-pVTZ level of theory. The 12 lowest-energy conformers of serine fall within a 8 kJ mol(-1) window, and for these species, geometric structures, precise relative energies, equilibrium and vibrationally averaged rotational constants, anharmonic vibrational frequencies, infrared intensities, quartic and sextic centrifugal distortion constants, dipole moments, and (14)N nuclear quadrupole coupling constants were computed. The relative energies were refined through composite focal-point analyses employing basis sets as large as aug-cc-pV5Z and correlation treatments through CCSD(T). The rotational constants for seven conformers measured by Fourier-transform microwave spectroscopy are in good agreement with the vibrationally averaged rotational constants computed in this study. Our anharmonic vibrational frequencies are compared to the large number of experimental vibrational absorptions attributable to at least six conformers.

  11. Transgender Adults' Access to College Bathrooms and Housing and the Relationship to Suicidality.

    PubMed

    Seelman, Kristie L

    2016-10-01

    Transgender and gender non-conforming people frequently experience discrimination, harassment, and marginalization across college and university campuses (Bilodeau, 2007; Finger, 2010; Rankin et al., 2010; Seelman et al., 2012). The minority stress model (Meyer, 2007) posits that experiences of discrimination often negatively impact the psychological wellbeing of minority groups. However, few scholars have examined whether college institutional climate factors-such as being denied access to bathrooms or gender-appropriate campus housing-are significantly associated with detrimental psychological outcomes for transgender people. Using the National Transgender Discrimination Survey, this study analyzes whether being denied access to these spaces is associated with lifetime suicide attempts, after controlling for interpersonal victimization by students or teachers. Findings from sequential logistic regression (N = 2,316) indicate that denial of access to either space had a significant relationship to suicidality, even after controlling for interpersonal victimization. This article discusses implications for higher education professionals and researchers.

  12. Conformal collineations and anisotropic fluids in general relativity

    NASA Astrophysics Data System (ADS)

    Duggal, K. L.; Sharma, R.

    1986-10-01

    Recently, Herrera et al. [L. Herrera, J. Jimenez, L. Leal, J. Ponce de Leon, M. Esculpi, and V. Galino, J. Math. Phys. 25, 3274 (1984)] studied the consequences of the existence of a one-parameter group of conformal motions for anisotropic matter. They concluded that for special conformal motions, the stiff equation of state (p=μ) is singled out in a unique way, provided the generating conformal vector field is orthogonal to the four-velocity. In this paper, the same problem is studied by using conformal collineations (which include conformal motions as subgroups). It is shown that, for a special conformal collineation, the stiff equation of state is not singled out. Non-Einstein Ricci-recurrent spaces are considered as physical models for the fluid matter.

  13. Network Visualization of Conformational Sampling during Molecular Dynamics Simulation

    PubMed Central

    Ahlstrom, Logan S.; Baker, Joseph Lee; Ehrlich, Kent; Campbell, Zachary T.; Patel, Sunita; Vorontsov, Ivan I.; Tama, Florence; Miyashita, Osamu

    2013-01-01

    Effective data reduction methods are necessary for uncovering the inherent conformational relationships present in large molecular dynamics (MD) trajectories. Clustering algorithms provide a means to interpret the conformational sampling of molecules during simulation by grouping trajectory snapshots into a few subgroups, or clusters, but the relationships between the individual clusters may not be readily understood. Here we show that network analysis can be used to visualize the dominant conformational states explored during simulation as well as the connectivity between them, providing a more coherent description of conformational space than traditional clustering techniques alone. We compare the results of network visualization against 11 clustering algorithms and principal component conformer plots. Several MD simulations of proteins undergoing different conformational changes demonstrate the effectiveness of networks in reaching functional conclusions. PMID:24211466

  14. Nucleosome structure and conformational changes

    SciTech Connect

    McGhee, J.D.; Felsenfeld, G.; Eisenberg, H.

    1980-10-01

    We have used a variety of chemical probes to measure the accessibility of DNA on the surface of the nucleosome. We review these results, and describe new experiments which show that T4 phage DNA can form complexes with the core histones, possessing the properties of normal nucleosomes. Since T4 DNA is largely occupied by glucose residues in the major groove, this suggests that the major groove is not filled with histone amino acid side chains. We also report results of recent measurements which appear to show that only a few strong charge interactions are involved in the attachment of the terminal 20 nucleotide pairs at each end of nucleosome core DNA. We speculate on the possible functional significance of the accessibility of DNA revealed by all of these experiments. We have also examined conformational changes induced in nucleosomes at high ionic strength (0.5 to 0.7M NaCl). The frictional coefficient is found to undergo a small increase in this region, not consistent with models in which the nucleosome is completely unfolded, but possibly reflecting the dissociation of terminal DNA from the nucleosome surface.

  15. Dual conformal transformations of smooth holographic Wilson loops

    NASA Astrophysics Data System (ADS)

    Dekel, Amit

    2017-01-01

    We study dual conformal transformations of minimal area surfaces in AdS5 ×S5 corresponding to holographic smooth Wilson loops and some other related observables. To act with dual conformal transformations we map the string solutions to the dual space by means of T-duality, then we apply a conformal transformation and finally T-dualize back to the original space. The transformation maps between string solutions with different boundary contours. The boundary contours of the minimal surfaces are not mapped back to the AdS boundary, and the regularized area of the surface changes.

  16. Permission to Speak: A Novel Formal Foundation for Access Control

    DTIC Science & Technology

    2016-06-21

    NAME(S) AND ADDRESS(ES) University of Pennsylvania,Computer and Information Science ,Philadelphia,PA,19104 8. PERFORMING ORGANIZATION REPORT NUMBER... science • Uniform treatment of access control and conformanceAccess control is verification of permissions – Conformance is satisfaction of

  17. Seed conformal blocks in 4D CFT

    NASA Astrophysics Data System (ADS)

    Echeverri, Alejandro Castedo; Elkhidir, Emtinan; Karateev, Denis; Serone, Marco

    2016-02-01

    We compute in closed analytical form the minimal set of "seed" conformal blocks associated to the exchange of generic mixed symmetry spinor/tensor operators in an arbitrary representation ( ℓ, overline{ℓ} ) of the Lorentz group in four dimensional conformal field theories. These blocks arise from 4-point functions involving two scalars, one (0, | ℓ - overline{7ell;} |) and one (| ℓ - overline{ℓ} |, 0) spinors or tensors. We directly solve the set of Casimir equations, that can elegantly be written in a compact form for any ( ℓ, overline{ℓ} ), by using an educated ansatz and reducing the problem to an algebraic linear system. Various details on the form of the ansatz have been deduced by using the so called shadow formalism. The complexity of the conformal blocks depends on the value of p = | ℓ - overline{ℓ} | and grows with p, in analogy to what happens to scalar conformal blocks in d even space-time dimensions as d increases. These results open the way to bootstrap 4-point functions involving arbitrary spinor/tensor operators in four dimensional conformal field theories.

  18. Conformational properties of pyrethroids

    NASA Astrophysics Data System (ADS)

    Mullaley, Anne; Taylor, Robin

    1994-04-01

    X-ray database searches and theoretical potential-energy calculations indicate that the acid moieties of pyrethroid cyclopropanecarboxylate esters adopt a well-defined, relatively inflexible conformation. In contrast, the alcohol moieties can exist in many low-energy geometries. One of the least conformationally flexible pyrethroid alcohols is 4-phenylindan-2-ol. The approximate overall conformation adopted at the biological binding site by insecticidal esters of this alcohol can be deduced with reasonable confidence by molecular modelling. Graphics superposition of a variety of pyrethroid acids suggests the existence of a large but rather narrow pocket at the binding site, in which substituents at the 3-position of the cyclopropane ring can be accommodated. This pocket is asymmetric with respect to the plane of the cyclopropane ring, extending further on the side remote from the ester group. The effects of α-substitution on the insecticidal activity of pyrethroid esters may be due to the influence of substituents on the preferred conformations of the molecules. This hypothesis rationalises the paradoxical dependence on absolute stereochemistry of the activities of various allylbenzyl and cinnamyl alcohol derivatives.

  19. Conformal cloak for waves

    SciTech Connect

    Chen Huanyang; Leonhardt, Ulf; Tyc, Tomas

    2011-05-15

    Conformal invisibility devices are only supposed to work within the valid range of geometrical optics. Here, we show by numerical simulations and analytical arguments that for certain quantized frequencies, they are nearly perfect even in a regime that clearly violates geometrical optics. The quantization condition follows from the analogy between the Helmholtz equation and the stationary Schroedinger equation.

  20. Arteriovenous Access

    PubMed Central

    MacRae, Jennifer M.; Dipchand, Christine; Oliver, Matthew; Moist, Louise; Yilmaz, Serdar; Lok, Charmaine; Leung, Kelvin; Clark, Edward; Hiremath, Swapnil; Kappel, Joanne; Kiaii, Mercedeh; Luscombe, Rick; Miller, Lisa M.

    2016-01-01

    Complications of vascular access lead to morbidity and may reduce quality of life. In this module, we review both infectious and noninfectious arteriovenous access complications including neuropathy, aneurysm, and high-output access. For the challenging patients who have developed many complications and are now nearing their last vascular access, we highlight some potentially novel approaches. PMID:28270919

  1. Reversible ratchet effects for vortices in conformal pinning arrays

    SciTech Connect

    Reichhardt, Charles; Ray, Dipanjan; Reichhardt, Cynthia Jane Olson

    2015-05-04

    A conformal transformation of a uniform triangular pinning array produces a structure called a conformal crystal which preserves the sixfold ordering of the original lattice but contains a gradient in the pinning density. Here we use numerical simulations to show that vortices in type-II superconductors driven with an ac drive over gradient pinning arrays produce the most pronounced ratchet effect over a wide range of parameters for a conformal array, while square gradient or random gradient arrays with equivalent pinning densities give reduced ratchet effects. In the conformal array, the larger spacing of the pinning sites in the direction transverse to the ac drive permits easy funneling of interstitial vortices for one driving direction, producing the enhanced ratchet effect. In the square array, the transverse spacing between pinning sites is uniform, giving no asymmetry in the funneling of the vortices as the driving direction switches, while in the random array, there are numerous easy-flow channels present for either direction of drive. We find multiple ratchet reversals in the conformal arrays as a function of vortex density and ac amplitude, and correlate the features with a reversal in the vortex ordering, which is greater for motion in the ratchet direction. In conclusion, the enhanced conformal pinning ratchet effect can also be realized for colloidal particles moving over a conformal array, indicating the general usefulness of conformal structures for controlling the motion of particles.

  2. Reversible ratchet effects for vortices in conformal pinning arrays

    DOE PAGES

    Reichhardt, Charles; Ray, Dipanjan; Reichhardt, Cynthia Jane Olson

    2015-05-04

    A conformal transformation of a uniform triangular pinning array produces a structure called a conformal crystal which preserves the sixfold ordering of the original lattice but contains a gradient in the pinning density. Here we use numerical simulations to show that vortices in type-II superconductors driven with an ac drive over gradient pinning arrays produce the most pronounced ratchet effect over a wide range of parameters for a conformal array, while square gradient or random gradient arrays with equivalent pinning densities give reduced ratchet effects. In the conformal array, the larger spacing of the pinning sites in the direction transversemore » to the ac drive permits easy funneling of interstitial vortices for one driving direction, producing the enhanced ratchet effect. In the square array, the transverse spacing between pinning sites is uniform, giving no asymmetry in the funneling of the vortices as the driving direction switches, while in the random array, there are numerous easy-flow channels present for either direction of drive. We find multiple ratchet reversals in the conformal arrays as a function of vortex density and ac amplitude, and correlate the features with a reversal in the vortex ordering, which is greater for motion in the ratchet direction. In conclusion, the enhanced conformal pinning ratchet effect can also be realized for colloidal particles moving over a conformal array, indicating the general usefulness of conformal structures for controlling the motion of particles.« less

  3. Assessing the Impact of Backbone Length and Capping Agent on the Conformational Preferences of a Model Peptide: Conformation Specific IR and UV Spectroscopy of 2-AMINOISOBUTYRIC Acid

    NASA Astrophysics Data System (ADS)

    Gord, Joseph R.; Hewett, Daniel M.; Kubasik, Matthew A.; Zwier, Timothy S.

    2015-06-01

    2-Aminoisobutyric acid (Aib) is an achiral, α-amino acid having two equivalent methyl groups attached to C_α. Extended Aib oligomers are known to have a strong preference for the adoption of a 310-helical structure in the condensed phase. Here, we have taken a simplifying step and focused on the intrinsic folding propensities of Aib by looking at a series of capped Aib oligomers in the gas phase, free from the influence of solvent molecules and cooled in a supersonic expansion. Resonant two-photon ionization and IR-UV holeburning have been used to record single-conformation UV spectra using the Z-cap as the UV chromophore. Resonant ion-dip infrared (RIDIR) spectroscopy provides single-conformation IR spectra in the OH stretch and NH stretch regions. Data have been collected on a set of Z-(Aib)n-X oligomers with n = 1, 2, 4, 6 and X = -OH and -OMethyl. The impacts of these capping groups and differences in backbone length have been found to dramatically influence the conformational space accessed by the molecules studied here. Oligomers of n=4 have sufficient backbone length for a full turn of the 310-helix to be formed. Early interpretation of the data collected shows clear spectroscopic markers signaling the onset of 310-helix formation as well as evidence of structures incorporating C7 and C14 hydrogen bonded rings. Toniolo, C.; Bonora, G. M.; Barone, V.; Bavoso, A.; Benedetti, E.; Di Blasio, B.; Grimaldi, P.; Lelj, F.; Pavone, V.; Pedone, C., Conformation of Pleionomers of α-Aminoisobutyric Acid. Macromolecules 1985, 18, 895-902.

  4. Transportation Conformity Training and Presentations

    EPA Pesticide Factsheets

    EPA's OTAQ has provided multiple conformity training sessions in the past to assist state and local governments in implementing conformity requirements. As training information is prepared for other venues, it will be posted on this page.

  5. Microscopic insights into the NMR relaxation-based protein conformational entropy meter.

    PubMed

    Kasinath, Vignesh; Sharp, Kim A; Wand, A Joshua

    2013-10-09

    Conformational entropy is a potentially important thermodynamic parameter contributing to protein function. Quantitative measures of conformational entropy are necessary for an understanding of its role but have been difficult to obtain. An empirical method that utilizes changes in conformational dynamics as a proxy for changes in conformational entropy has recently been introduced. Here we probe the microscopic origins of the link between conformational dynamics and conformational entropy using molecular dynamics simulations. Simulation of seven proteins gave an excellent correlation with measures of side-chain motion derived from NMR relaxation. The simulations show that the motion of methyl-bearing side chains are sufficiently coupled to that of other side chains to serve as excellent reporters of the overall side-chain conformational entropy. These results tend to validate the use of experimentally accessible measures of methyl motion--the NMR-derived generalized order parameters--as a proxy from which to derive changes in protein conformational entropy.

  6. Multiscale conformal pattern transfer

    PubMed Central

    Lodewijks, Kristof; Miljkovic, Vladimir; Massiot, Inès; Mekonnen, Addis; Verre, Ruggero; Olsson, Eva; Dmitriev, Alexandre

    2016-01-01

    We demonstrate a method for seamless transfer from a parent flat substrate of basically any lithographic top-down or bottom-up pattern onto essentially any kind of surface. The nano- or microscale patterns, spanning macroscopic surface areas, can be transferred with high conformity onto a large variety of surfaces when such patterns are produced on a thin carbon film, grown on top of a sacrificial layer. The latter allows lifting the patterns from the flat parent substrate onto a water-air interface to be picked up by the host surface of choice. We illustrate the power of this technique by functionalizing broad range of materials including glass, plastics, metals, rough semiconductors and polymers, highlighting the potential applications in in situ colorimetry of the chemistry of materials, anti-counterfeit technologies, biomolecular and biomedical studies, light-matter interactions at the nanoscale, conformal photovoltaics and flexible electronics. PMID:27329824

  7. Multiscale conformal pattern transfer

    NASA Astrophysics Data System (ADS)

    Lodewijks, Kristof; Miljkovic, Vladimir; Massiot, Inès; Mekonnen, Addis; Verre, Ruggero; Olsson, Eva; Dmitriev, Alexandre

    2016-06-01

    We demonstrate a method for seamless transfer from a parent flat substrate of basically any lithographic top-down or bottom-up pattern onto essentially any kind of surface. The nano- or microscale patterns, spanning macroscopic surface areas, can be transferred with high conformity onto a large variety of surfaces when such patterns are produced on a thin carbon film, grown on top of a sacrificial layer. The latter allows lifting the patterns from the flat parent substrate onto a water-air interface to be picked up by the host surface of choice. We illustrate the power of this technique by functionalizing broad range of materials including glass, plastics, metals, rough semiconductors and polymers, highlighting the potential applications in in situ colorimetry of the chemistry of materials, anti-counterfeit technologies, biomolecular and biomedical studies, light-matter interactions at the nanoscale, conformal photovoltaics and flexible electronics.

  8. Conformational flexibility of aspartame.

    PubMed

    Toniolo, Claudio; Temussi, Pierandrea

    2016-05-01

    L-Aspartyl-L-phenylalanine methyl ester, better known as aspartame, is not only one of the most used artificial sweeteners, but also a very interesting molecule with respect to the correlation between molecular structure and taste. The extreme conformational flexibility of this dipeptide posed a huge difficulty when researchers tried to use it as a lead compound to design new sweeteners. In particular, it was difficult to take advantage of its molecular model as a mold to infer the shape of the, then unknown, active site of the sweet taste receptor. Here, we follow the story of the 3D structural aspects of aspartame from early conformational studies to recent docking into homology models of the receptor. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 376-384, 2016.

  9. Conformal ALON® windows

    NASA Astrophysics Data System (ADS)

    Goldman, Lee M.; Balasubramanian, Sreeram; Smith, Mark; Nag, Nagendra; Foti, Robyn; Jha, Santosh; Sastri, Suri

    2014-05-01

    Aluminum Oxynitride (ALON® Optical Ceramic) combines broadband transparency with excellent mechanical properties. ALON's cubic structure means that it is transparent in its polycrystalline form, allowing it to be manufactured by conventional powder processing techniques. Surmet controls every aspect of the manufacturing process, beginning with synthesis of ALON® powder, continuing through forming/heat treatment of blanks, ending with optical fabrication of ALON® windows. Surmet has made significant progress in its production capability in recent years. Additional scale up of Surmet's manufacturing capability, for complex geometries, larger sizes and higher quantities, is underway. The requirements for modern aircraft are driving the need for conformal windows for future sensor systems. However, limitations on optical systems and the ability to produce windows in complex geometries currently limit the geometry of existing windows and window assemblies to faceted assemblies of flat windows. Surmet's ability to produce large curved ALON® blanks is an important step in the development of conformal windows for future aircraft applications.

  10. Conformal scalar field wormholes

    NASA Technical Reports Server (NTRS)

    Halliwell, Jonathan J.; Laflamme, Raymond

    1989-01-01

    The Euclidian Einstein equations with a cosmological constant and a conformally coupled scalar field are solved, taking the metric to be of the Robertson-Walker type. In the case Lambda = 0, solutions are found which represent a wormhole connecting two asymptotically flat Euclidian regions. In the case Lambda greater than 0, the solutions represent tunneling from a small Tolman-like universe to a large Robertson-Walker universe.

  11. The conformal bootstrap

    NASA Astrophysics Data System (ADS)

    Poland, David; Simmons-Duffin, David

    2016-06-01

    The conformal bootstrap was proposed in the 1970s as a strategy for calculating the properties of second-order phase transitions. After spectacular success elucidating two-dimensional systems, little progress was made on systems in higher dimensions until a recent renaissance beginning in 2008. We report on some of the main results and ideas from this renaissance, focusing on new determinations of critical exponents and correlation functions in the three-dimensional Ising and O(N) models.

  12. Conformations of organophosphine oxides

    SciTech Connect

    De Silva, Nuwan; Zahariev, Federico; Hay, Benjamin P.; Gordon, Mark S.; Windus, Theresa L.

    2015-07-17

    The conformations of a series of organophosphine oxides, OP(CH3)2R, where R = methyl, ethyl, isopropyl, tert-butyl, vinyl, and phenyl, are predicted using the MP2/cc-pVTZ level of theory. Comparison of potential energy surfaces for rotation about P–C bonds with crystal structure data reveals a strong correlation between predicted location and energetics of minima and histograms of dihedral angle distributions observed in the solid state. In addition, the most stable conformers are those that minimize the extent of steric repulsion between adjacent rotor substituents, and the torsional barriers tend to increase with the steric bulk of the rotating alkyl group. MM3 force field parameters were adjusted to fit the MP2 results, providing a fast and accurate model for predicting organophosphine oxides shapes—an essential part of understanding the chemistry of these compounds. As a result, the predictive power of the modified MM3 model was tested against MP2/cc-pVTZ conformations for triethylphosphine oxide, OP(CH2CH3)3, and triphenylphosphine oxide, OP(Ph)3.

  13. Conformations of organophosphine oxides

    DOE PAGES

    De Silva, Nuwan; Zahariev, Federico; Hay, Benjamin P.; ...

    2015-07-17

    The conformations of a series of organophosphine oxides, OP(CH3)2R, where R = methyl, ethyl, isopropyl, tert-butyl, vinyl, and phenyl, are predicted using the MP2/cc-pVTZ level of theory. Comparison of potential energy surfaces for rotation about P–C bonds with crystal structure data reveals a strong correlation between predicted location and energetics of minima and histograms of dihedral angle distributions observed in the solid state. In addition, the most stable conformers are those that minimize the extent of steric repulsion between adjacent rotor substituents, and the torsional barriers tend to increase with the steric bulk of the rotating alkyl group. MM3 forcemore » field parameters were adjusted to fit the MP2 results, providing a fast and accurate model for predicting organophosphine oxides shapes—an essential part of understanding the chemistry of these compounds. As a result, the predictive power of the modified MM3 model was tested against MP2/cc-pVTZ conformations for triethylphosphine oxide, OP(CH2CH3)3, and triphenylphosphine oxide, OP(Ph)3.« less

  14. Appendage mountable electronic devices conformable to surfaces

    DOEpatents

    Rogers, John; Ying, Ming; Bonifas, Andrew; Lu, Nanshu

    2017-01-24

    Disclosed are appendage mountable electronic systems and related methods for covering and conforming to an appendage surface. A flexible or stretchable substrate has an inner surface for receiving an appendage, including an appendage having a curved surface, and an opposed outer surface that is accessible to external surfaces. A stretchable or flexible electronic device is supported by the substrate inner and/or outer surface, depending on the application of interest. The electronic device in combination with the substrate provides a net bending stiffness to facilitate conformal contact between the inner surface and a surface of the appendage provided within the enclosure. In an aspect, the system is capable of surface flipping without adversely impacting electronic device functionality, such as electronic devices comprising arrays of sensors, actuators, or both sensors and actuators.

  15. Electrical control of protein conformation.

    PubMed

    Wan, Alwin M D; Schur, Rebecca M; Ober, Christopher K; Fischbach, Claudia; Gourdon, Delphine; Malliaras, George G

    2012-05-08

    Conducting polymer devices that enable precise control of fibronectin conformation over macroscopic areas are reported. Single conformations as well as conformation gradients are achieved by applying an appropriate potential. These surfaces remain biologically relevant and support cell culture; hence, they may serve as a model to understand and control cell-surface interactions, with applications in basic research, medical diagnostics, and tissue engineering.

  16. Trends for isolated amino acids and dipeptides: Conformation, divalent ion binding, and remarkable similarity of binding to calcium and lead

    NASA Astrophysics Data System (ADS)

    Ropo, M.; Blum, V.; Baldauf, C.

    2016-11-01

    We derive structural and binding energy trends for twenty amino acids, their dipeptides, and their interactions with the divalent cations Ca2+, Ba2+, Sr2+, Cd2+, Pb2+, and Hg2+. The underlying data set consists of more than 45,000 first-principles predicted conformers with relative energies up to ~4 eV (~400 kJ/mol). We show that only very few distinct backbone structures of isolated amino acids and their dipeptides emerge as lowest-energy conformers. The isolated amino acids predominantly adopt structures that involve an acidic proton shared between the carboxy and amino function. Dipeptides adopt one of two intramolecular-hydrogen bonded conformations C5 or . Upon complexation with a divalent cation, the accessible conformational space shrinks and intramolecular hydrogen bonding is prevented due to strong electrostatic interaction of backbone and side chain functional groups with cations. Clear correlations emerge from the binding energies of the six divalent ions with amino acids and dipeptides. Cd2+ and Hg2+ show the largest binding energies–a potential correlation with their known high acute toxicities. Ca2+ and Pb2+ reveal almost identical binding energies across the entire series of amino acids and dipeptides. This observation validates past indications that ion-mimicry of calcium and lead should play an important role in a toxicological context.

  17. Trends for isolated amino acids and dipeptides: Conformation, divalent ion binding, and remarkable similarity of binding to calcium and lead

    PubMed Central

    Ropo, M.; Blum, V.; Baldauf, C.

    2016-01-01

    We derive structural and binding energy trends for twenty amino acids, their dipeptides, and their interactions with the divalent cations Ca2+, Ba2+, Sr2+, Cd2+, Pb2+, and Hg2+. The underlying data set consists of more than 45,000 first-principles predicted conformers with relative energies up to ~4 eV (~400 kJ/mol). We show that only very few distinct backbone structures of isolated amino acids and their dipeptides emerge as lowest-energy conformers. The isolated amino acids predominantly adopt structures that involve an acidic proton shared between the carboxy and amino function. Dipeptides adopt one of two intramolecular-hydrogen bonded conformations C5 or . Upon complexation with a divalent cation, the accessible conformational space shrinks and intramolecular hydrogen bonding is prevented due to strong electrostatic interaction of backbone and side chain functional groups with cations. Clear correlations emerge from the binding energies of the six divalent ions with amino acids and dipeptides. Cd2+ and Hg2+ show the largest binding energies–a potential correlation with their known high acute toxicities. Ca2+ and Pb2+ reveal almost identical binding energies across the entire series of amino acids and dipeptides. This observation validates past indications that ion-mimicry of calcium and lead should play an important role in a toxicological context. PMID:27808109

  18. Enhanced conformational sampling using enveloping distribution sampling.

    PubMed

    Lin, Zhixiong; van Gunsteren, Wilfred F

    2013-10-14

    To lessen the problem of insufficient conformational sampling in biomolecular simulations is still a major challenge in computational biochemistry. In this article, an application of the method of enveloping distribution sampling (EDS) is proposed that addresses this challenge and its sampling efficiency is demonstrated in simulations of a hexa-β-peptide whose conformational equilibrium encompasses two different helical folds, i.e., a right-handed 2.7(10∕12)-helix and a left-handed 3(14)-helix, separated by a high energy barrier. Standard MD simulations of this peptide using the GROMOS 53A6 force field did not reach convergence of the free enthalpy difference between the two helices even after 500 ns of simulation time. The use of soft-core non-bonded interactions in the centre of the peptide did enhance the number of transitions between the helices, but at the same time led to neglect of relevant helical configurations. In the simulations of a two-state EDS reference Hamiltonian that envelops both the physical peptide and the soft-core peptide, sampling of the conformational space of the physical peptide ensures that physically relevant conformations can be visited, and sampling of the conformational space of the soft-core peptide helps to enhance the transitions between the two helices. The EDS simulations sampled many more transitions between the two helices and showed much faster convergence of the relative free enthalpy of the two helices compared with the standard MD simulations with only a slightly larger computational effort to determine optimized EDS parameters. Combined with various methods to smoothen the potential energy surface, the proposed EDS application will be a powerful technique to enhance the sampling efficiency in biomolecular simulations.

  19. Construction of all N =4 conformal supergravities

    NASA Astrophysics Data System (ADS)

    Butter, Daniel; Ciceri, Franz; de Wit, Bernard; Sahoo, Bindusar

    2017-02-01

    All N =4 conformal supergravities in four space-time dimensions are constructed. These are the only N =4 supergravity theories whose actions are invariant under off-shell supersymmetry. They are encoded in terms of a holomorphic function that is homogeneous of zeroth degree in scalar fields that parametrize an SU (1 ,1 )/U (1 ) coset space. When this function equals a constant the Lagrangian is invariant under continuous SU(1,1) transformations. The construction of these higher-derivative invariants also opens the door to various applications for nonconformal theories.

  20. Wide-angle conformal IR transceiver

    NASA Astrophysics Data System (ADS)

    Liepmann, Till W.; Randall, Michael R.; Shapiro, Alan R.

    1993-08-01

    Accessing a large field-of-regard (FOR) from an aircraft-mounted infrared system imposes significant structural and aerodynamic penalties. A novel conformal infrared (IR) transceiver concept is presented which is currently under development. A trial design of this concept can access a 160 deg FOR without a gimbal mirror or 'fish eye' lens. A fiber optic bundle is used to allow a wide range of beamsteering technologies with small steering angles (i.e., +/- 5 degree(s)) to access the large FOR (+/- 80 deg) through a single, conformal aperture. The output lens size is less than a factor of three times larger than the input/output IR beam, yet provides near diffraction limited polychromatic collimation over the full FOR. The concept is applicable over a wide spectral band (ultraviolet to far IR), however, it is being developed for the mid-IR (2 - 6 micron) band. The challenging technical aspects of the fiber optics in this spectral band are discussed.

  1. Paving the Way for Small Satellite Access to Orbit: Cyclops' Deployment of SpinSat, the Largest Satellite Ever Deployed from the International Space Station

    NASA Technical Reports Server (NTRS)

    Hershey, Matthew P.; Newswander, Daniel R.; Smith, James P.; Lamb, Craig R.; Ballard, Perry G.

    2015-01-01

    The Space Station Integrated Kinetic Launcher for Orbital Payload Systems (SSIKLOPS), known as "Cyclops" to the International Space Station (ISS) community, successfully deployed the largest satellite ever (SpinSat) from the ISS on November 28, 2014. Cyclops, a collaboration between the NASA ISS Program, NASA Johnson Space Center Engineering, and Department of Defense Space Test Program (DoD STP) communities, is a dedicated 10-100 kg class ISS small satellite deployment system. This paper will showcase the successful deployment of SpinSat from the ISS. It will also outline the concept of operations, interfaces, requirements, and processes for satellites to utilize the Cyclops satellite deployment system.

  2. Conformal Janus on Euclidean sphere

    NASA Astrophysics Data System (ADS)

    Bak, Dongsu; Gustavsson, Andreas; Rey, Soo-Jong

    2016-12-01

    We interpret Janus as an interface in a conformal field theory and study its properties. The Janus is created by an exactly marginal operator and we study its effect on the interface conformal field theory on the Janus. We do this by utilizing the AdS/CFT correspondence. We compute the interface free energy both from leading correction to the Euclidean action in the dual gravity description and from conformal perturbation theory in the conformal field theory. We find that the two results agree each other and that the interface free energy scales precisely as expected from the conformal invariance of the Janus interface.

  3. Conformal vectors and stellar models

    NASA Astrophysics Data System (ADS)

    Manjonjo, A. M.; Maharaj, S. D.; Moopanar, S.

    2017-02-01

    The relationship between conformal symmetries and relativistic spheres in astrophysics is studied. We use the nonvanishing components of the Weyl tensor to classify the conformal symmetries in static spherical spacetimes. It is possible to find an explicit connection between the two gravitational potentials for both conformally flat and nonconformally flat cases. We show that the conformal Killing vector admits time dependence in terms of quadratic, trigonometric and hyperbolic functions. The Einstein and Einstein-Maxwell field equations can be written in terms of a single potential, any choice of which leads to an exact solution. Previous results of conformally invariant static spheres are contained in our treatment.

  4. 14 CFR 325.14 - Conformity with subpart A of part 302.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Conformity with subpart A of part 302. 325.14 Section 325.14 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) PROCEDURAL REGULATIONS ESSENTIAL AIR SERVICE PROCEDURES § 325.14 Conformity...

  5. 14 CFR 314.3 - Conformity with subpart A of part 302.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Conformity with subpart A of part 302. 314.3 Section 314.3 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) PROCEDURAL REGULATIONS EMPLOYEE PROTECTION PROGRAM General § 314.3 Conformity...

  6. 14 CFR 325.14 - Conformity with subpart A of part 302.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Conformity with subpart A of part 302. 325.14 Section 325.14 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) PROCEDURAL REGULATIONS ESSENTIAL AIR SERVICE PROCEDURES § 325.14 Conformity...

  7. Systematic conformational investigations of peptoids and peptoid-peptide chimeras.

    PubMed

    Brandt, Wolfgang; Herberg, Thomas; Wessjohann, Ludger

    2011-01-01

    Peptoids are originally defined as N-substituted oligoglycine derivatives, and in a broader definition as N-substituted peptides (peptoid-peptide chimeras). Both types were systematically investigated by force field calculations. The Merck MMFF and YASARA2 force fields were shown to be, among others, the most suitable ones for conformational investigations of peptoids with no missing parameterizations, in contrast to AMBER or CHARMM. Ramachandran-like plots were calculated for dipeptoids and chimeras using energy calculations and grid searches by varying the dihedral angels PHI and PSI in steps of 10 degrees for s-cis- and s-trans amide bonds. Barriers as well as low energy conformations are compared to peptide Ramachandran plots, showing that peptoids have both, more barriers due to additional steric interactions as well as access to minimum conformations not accessible by peptides. Low energy conformations of dimers were used as starting conformations of higher oligomers of the peptoids for extensive molecular dynamics simulations over 10 or 20 ns with the YASARA2 force field and an explicit water solvent box to evaluate their potential to form secondary structural elements. Especially peptoids with aminoisobutyric acid-like monomer units were found to form left-handed or polyproline-like helices also known from less common natural peptides. Furthermore, new secondary structures appear feasible based on stable conformations outside the allowed areas of the Ramachandran plot for peptides, but allowed for peptoids.

  8. Simulating Massive Conformation Changes within Polypeptide Systems

    NASA Astrophysics Data System (ADS)

    Singh, Jaspinder Paul

    In this dissertation I employ all-atom structure based models with stable energy basins to several existing and novel polypeptide systems (postulated conformation changes of the mammalian prion protein and structurally dual proteins). The common themes are finding unfolding and refolding pathways between highly dissimilar protein structures as a means of understanding exactly how and why a protein may misfold. The modeling is based on the energy funnel landscape theory of protein conformation space. The principle of minimal frustration is considered as the model includes parameters which vary the roughness of the landscape and give rise to off-pathway misfoldings. The dual basin model is applied to the C-terminal (residues 166-226) of the mammalian prion protein. One basin represents the known alpha-helical (aH) structure while the other represents the same residues in a lefthanded beta-helical (LHBH) conformation. The LHBH structure has been proposed to help describe one class of in vitro grown fibrils, as well as possibly self-templating the conversion of normal cellular prion protein to the infectious form. Yet, it is unclear how the protein may make this global rearrangement. Our results demonstrate that the conformation changes are not strongly limited by large-scale geometry modification and that there may exist an overall preference for the LHBH conformation. Furthermore, our model presents novel intermediate trapping conformations with twisted LHBH structure. Polypeptides that display structural duality have primary structures that can give rise to different potential native conformations. We apply the structure-based all-atom model to a leucine zipper protein template with a stable aH structure that has been shown in experiment to switch to a β hairpin structure when exposed to a low-pH environment. We show that the model can be used to perform large-scale temperature-dependent conformational switching by simulating this switching behavior. We augmented

  9. Conformation effects on the molecular orbitals of serine

    NASA Astrophysics Data System (ADS)

    Wang, Ke-Dong; Ma, Peng-Fei; Shan, Xu

    2011-03-01

    This paper calculates the five most stable conformers of serine with Hartree—Fock theory, density functional theory (B3LYP), Møller—Plesset perturbation theory (MP4(SDQ)) and electron propagation theory with the 6-311++G(2d,2p) basis set. The calculated vertical ionization energies for the valence molecular orbitals of each conformer are in agreement with the experimental data, indicating that a range of molecular conformations would coexist in an equilibrium sample. Information of the five outer valence molecular orbitals for each conformer is explored in coordinate and momentum spaces using dual space analysis to investigate the conformational processes, which are generated from the global minimum conformer Ser1 by rotation of C2-C3 (Ser4), C1-C2 (Ser5) and C1-O2 (Ser2 and Ser3). Orbitals 28a, 27a and 26a are identified as the fingerprint orbitals for all the conformational processes. Project supported by the Doctoral Research Fund of Henan Normal University, China (Grant No. 525449).

  10. OSI Conformance Testing for Bibliographic Applications.

    ERIC Educational Resources Information Center

    Arbez, Gilbert; Swain, Leigh

    1990-01-01

    Describes the development of Open Systems Interconnection (OSI) conformance testing sites, conformance testing tools, and conformance testing services. Discusses related topics such as interoperability testing, arbitration testing, and international harmonization of conformance testing. A glossary is included. (24 references) (SD)

  11. Metamaterials with conformational nonlinearity

    PubMed Central

    Lapine, Mikhail; Shadrivov, Ilya V.; Powell, David A.; Kivshar, Yuri S.

    2011-01-01

    Within a decade of fruitful development, metamaterials became a prominent area of research, bridging theoretical and applied electrodynamics, electrical engineering and material science. Being man-made structures, metamaterials offer a particularly useful playground to develop interdisciplinary concepts. Here we demonstrate a novel principle in metamaterial assembly which integrates electromagnetic, mechanical, and thermal responses within their elements. Through these mechanisms, the conformation of the meta-molecules changes, providing a dual mechanism for nonlinearity and offering nonlinear chirality. Our proposal opens a wide road towards further developments of nonlinear metamaterials and photonic structures, adding extra flexibility to their design and control. PMID:22355655

  12. Leaf growth is conformal

    NASA Astrophysics Data System (ADS)

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I.; Boudaoud, Arezki

    2016-10-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour.

  13. Web Accessibility and Accessibility Instruction

    ERIC Educational Resources Information Center

    Green, Ravonne A.; Huprich, Julia

    2009-01-01

    Section 508 of the Americans with Disabilities Act (ADA) mandates that programs and services be accessible to people with disabilities. While schools of library and information science (SLIS*) and university libraries should model accessible Web sites, this may not be the case. This article examines previous studies about the Web accessibility of…

  14. Hierarchical Docking of Databases of Multiple Ligand Conformations

    PubMed Central

    Lorber, David M.; Shoichet, Brian K.

    2006-01-01

    Ligand flexibility is an important problem in molecular docking and virtual screening. To address this challenge, we investigate a hierarchical pre-organization of multiple conformations of small molecules. Such organization of pre-calculated conformations removes the exploration of ligand conformational space from the docking calculation and allows for concise representation of what can be thousands of conformations. The hierarchy also recognizes and prunes incompatible conformations early in the calculation, eliminating redundant calculations of fit. We investigate the method by docking the MDL Drug Data Report (MDDR), an annotated database of 100,000 molecules, into apo and holo forms of seven unrelated targets. This annotated database allows us to track the ranking of tens to hundreds of annotated ligands in each of the docking systems. The binding sites and database are prepared in an automated fashion in an attempt to remove some human bias from the calculations. Many thousands of explicit and implicit ligand conformations may be docked in calculations not much longer than required for single conformer docking. As long as internal energies are not considered, recombination with the hierarchy is additive as the number of degrees of freedom is increased. Molecules with even millions of conformations can be docked in a few minutes on a single desktop computer. PMID:16101414

  15. Spherically symmetric conformal gravity and ''gravitational bubbles''

    SciTech Connect

    Berezin, V.A.; Dokuchaev, V.I.; Eroshenko, Yu.N. E-mail: dokuchaev@inr.ac.ru

    2016-01-01

    The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equations are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the ''gravitational bubbles'', which is compact and with zero Weyl tensor. Thus, we obtained the pure vacuum curved space-times (without any material sources, including the cosmological constant) what is absolutely impossible in General Relativity. Such a phenomenon makes it easier to create the universe from ''nothing''. The second class consists of the solutions with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly some features of non-vacuum solutions. Two of them are explicitly written, namely, the metrics à la Vaidya, and the electrovacuum space-time metrics.

  16. Spherically symmetric conformal gravity and ``gravitational bubbles''

    NASA Astrophysics Data System (ADS)

    Berezin, V. A.; Dokuchaev, V. I.; Eroshenko, Yu. N.

    2016-01-01

    The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equations are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the ``gravitational bubbles'', which is compact and with zero Weyl tensor. Thus, we obtained the pure vacuum curved space-times (without any material sources, including the cosmological constant) what is absolutely impossible in General Relativity. Such a phenomenon makes it easier to create the universe from ``nothing''. The second class consists of the solutions with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly some features of non-vacuum solutions. Two of them are explicitly written, namely, the metrics à la Vaidya, and the electrovacuum space-time metrics.

  17. Conformally symmetric traversable wormholes

    SciTech Connect

    Boehmer, Christian G.; Harko, Tiberiu; Lobo, Francisco S. N.

    2007-10-15

    Exact solutions of traversable wormholes are found under the assumption of spherical symmetry and the existence of a nonstatic conformal symmetry, which presents a more systematic approach in searching for exact wormhole solutions. In this work, a wide variety of solutions are deduced by considering choices for the form function, a specific linear equation of state relating the energy density and the pressure anisotropy, and various phantom wormhole geometries are explored. A large class of solutions impose that the spatial distribution of the exotic matter is restricted to the throat neighborhood, with a cutoff of the stress-energy tensor at a finite junction interface, although asymptotically flat exact solutions are also found. Using the 'volume integral quantifier', it is found that the conformally symmetric phantom wormhole geometries may, in principle, be constructed by infinitesimally small amounts of averaged null energy condition violating matter. Considering the tidal acceleration traversability conditions for the phantom wormhole geometry, specific wormhole dimensions and the traversal velocity are also deduced.

  18. The pseudo-conformal universe: scale invariance from spontaneous breaking of conformal symmetry

    SciTech Connect

    Hinterbichler, Kurt; Khoury, Justin E-mail: jkhoury@sas.upenn.edu

    2012-04-01

    We present a novel theory of the very early universe which addresses the traditional horizon and flatness problems of big bang cosmology and predicts a scale invariant spectrum of perturbations. Unlike inflation, this scenario requires no exponential accelerated expansion of space-time. Instead, the early universe is described by a conformal field theory minimally coupled to gravity. The conformal fields develop a time-dependent expectation value which breaks the flat space so(4,2) conformal symmetry down to so(4,1), the symmetries of de Sitter, giving perturbations a scale invariant spectrum. The solution is an attractor, at least in the case of a single time-dependent field. Meanwhile, the metric background remains approximately flat but slowly contracts, which makes the universe increasingly flat, homogeneous and isotropic, akin to the smoothing mechanism of ekpyrotic cosmology. Our scenario is very general, requiring only a conformal field theory capable of developing the appropriate time-dependent expectation values, and encompasses existing incarnations of this idea, specifically the U(1) model of Rubakov and the Galileon Genesis scenario. Its essential features depend only on the symmetry breaking pattern and not on the details of the underlying lagrangian. It makes generic observational predictions that make it potentially distinguishable from standard inflation, in particular significant non-gaussianities and the absence of primordial gravitational waves.

  19. Accessibility Standards, Illustrated.

    ERIC Educational Resources Information Center

    Jones, Michael A.

    The book sets forth Illinois environmental accessibility standards for disabled persons based on observation and interview data. Photographs, drawings, and detailed floor plans are included in sections dealing with human data (including space requirements for maneuvering wheelchairs, color blindness, incontinence, and severe auditory or visual…

  20. SpaceCube Mini

    NASA Technical Reports Server (NTRS)

    Lin, Michael; Petrick, David; Geist, Alessandro; Flatley, Thomas

    2012-01-01

    This version of the SpaceCube will be a full-fledged, onboard space processing system capable of 2500+ MIPS, and featuring a number of plug-andplay gigabit and standard interfaces, all in a condensed 3x3x3 form factor [less than 10 watts and less than 3 lb (approximately equal to 1.4 kg)]. The main processing engine is the Xilinx SIRF radiation- hardened-by-design Virtex-5 FX-130T field-programmable gate array (FPGA). Even as the SpaceCube 2.0 version (currently under test) is being targeted as the platform of choice for a number of the upcoming Earth Science Decadal Survey missions, GSFC has been contacted by customers who wish to see a system that incorporates key features of the version 2.0 architecture in an even smaller form factor. In order to fulfill that need, the SpaceCube Mini is being designed, and will be a very compact and low-power system. A similar flight system with this combination of small size, low power, low cost, adaptability, and extremely high processing power does not otherwise exist, and the SpaceCube Mini will be of tremendous benefit to GSFC and its partners. The SpaceCube Mini will utilize space-grade components. The primary processing engine of the Mini is the Xilinx Virtex-5 SIRF FX-130T radiation-hardened-by-design FPGA for critical flight applications in high-radiation environments. The Mini can also be equipped with a commercial Xilinx Virtex-5 FPGA with integrated PowerPCs for a low-cost, high-power computing platform for use in the relatively radiation- benign LEOs (low-Earth orbits). In either case, this version of the Space-Cube will weigh less than 3 pounds (.1.4 kg), conform to the CubeSat form-factor (10x10x10 cm), and will be low power (less than 10 watts for typical applications). The SpaceCube Mini will have a radiation-hardened Aeroflex FPGA for configuring and scrubbing the Xilinx FPGA by utilizing the onboard FLASH memory to store the configuration files. The FLASH memory will also be used for storing algorithm and

  1. Deep inelastic scattering in conformal QCD

    NASA Astrophysics Data System (ADS)

    Cornalba, Lorenzo; Costa, Miguel S.; Penedones, João

    2010-03-01

    We consider the Regge limit of a CFT correlation function of two vector and two scalar operators, as appropriate to study small-x deep inelastic scattering in mathcal{N} = 4 SYM or in QCD assuming approximate conformal symmetry. After clarifying the nature of the Regge limit for a CFT correlator, we use its conformal partial wave expansion to obtain an impact parameter representation encoding the exchange of a spin j Reggeon for any value of the coupling constant. The CFT impact parameter space is the three-dimensional hyperbolic space H 3, which is the impact parameter space for high energy scattering in the dual AdS space. We determine the small-x structure functions associated to the exchange of a Reggeon. We discuss unitarization from the point of view of scattering in AdS and comment on the validity of the eikonal approximation. We then focus on the weak coupling limit of the theory where the amplitude is dominated by the exchange of the BFKL pomeron. Conformal invariance fixes the form of the vector impact factor and its decomposition in transverse spin 0 and spin 2 components. Our formalism reproduces exactly the general results predict by the Regge theory, both for a scalar target and for γ* - γ* scattering. We compute current impact factors for the specific examples of mathcal{N} = 4 SYM and QCD, obtaining very simple results. In the case of the R-current of mathcal{N} = 4 SYM, we show that the transverse spin 2 component vanishes. We conjecture that the impact factors of all chiral primary operators of mathcal{N} = 4 SYM only have components with 0 transverse spin.

  2. Chromosome Conformation Capture in Primary Human Cells.

    PubMed

    Cortesi, Alice; Bodega, Beatrice

    2016-01-01

    3D organization of the genome, its structural and regulatory function of cell identity, is acquiring prominent features in epigenetics studies; more efforts have been done to develop techniques that allow studying nuclear structure. Chromosome conformation capture (3C) has been set up in 2002 from Dekker and from that moment great investments were made to develop genomics variants of 3C technology (4C, 5C, Hi-C) providing new tools to investigate the shape of the genome in a more systematic and unbiased manner. 3C method allows scientists to fix dynamic and variable 3D interactions in nuclear space, and consequently to study which sequences interact, how a gene is regulated by different and distant enhancer, or how a set of enhancer could regulate transcriptional units; to follow the conformation that mediates regulation change in development; and to evaluate if this fine epigenetic mechanism is impaired in disease condition.

  3. Distinguishing Signatures of Multipathway Conformational Transitions

    NASA Astrophysics Data System (ADS)

    Pierse, Christopher A.; Dudko, Olga K.

    2017-02-01

    The folding and binding of biomolecules into functional conformations are thought to be commonly mediated by multiple pathways rather than a unique route. Yet even in experiments where one can "see" individual conformational transitions, their stochastic nature generally precludes one from determining whether the transitions occurred through one or multiple pathways. We establish model-free, observable signatures in the response of macromolecules to force that unambiguously identify multiple pathways—even when the pathways themselves cannot be resolved. The unified analytical description reveals that, through multiple pathways, the response of molecules to external forces can be shaped in diverse ways, resulting in a rich design space for a tailored biological function already at the single-molecule level.

  4. Recent Advances in Conformal Gravity

    NASA Astrophysics Data System (ADS)

    O'Brien, James; Chaykov, Spasen

    2016-03-01

    In recent years, significant advances have been made in alternative gravitational theories. Although MOND remains the leading candidate among the alternative models, Conformal Gravity has been studied by Mannheim and O'Brien to solve the rotation curve problem without the need for dark matter. Recently, Mannheim, O'Brien and Chaykov have begun solving other gravitational questions in Conformal Gravity. In this presentation, we highlight the new work of Conformal Gravity's application to random motions of clusters (the original Zwicky problem), gravitational bending of light, gravitational lensing and a very recent survey of dwarf galaxy rotation curves. We will show in each case that Conformal Gravity can provide an accurate explanation and prediction of the data without the need for dark matter. Coupled with the fact that Conformal Gravity is a fully re-normalizable metric theory of gravity, these results help to push Conformal Gravity onto a competitive stage against other alternative models.

  5. Fermion-scalar conformal blocks

    SciTech Connect

    Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran

    2016-04-13

    In this study, we compute the conformal blocks associated with scalar-scalar-fermionfermion 4-point functions in 3D CFTs. Together with the known scalar conformal blocks, our result completes the task of determining the so-called ‘seed blocks’ in three dimensions. In addition, conformal blocks associated with 4-point functions of operators with arbitrary spins can now be determined from these seed blocks by using known differential operators.

  6. Conformal array antenna subsystem

    NASA Astrophysics Data System (ADS)

    1985-04-01

    An antenna subsystem to communicate between Ariane 4 and a data relay satellite was studied, concluding that the original ideas on ring antennas should be corrected due to the wide margin of coverage required in elevation for such antennas, which implies the need of splitting the coverage. Nevertheless, the study of cylindrical and conical conformal arrays was continued in view of their intrinsic interest. Needed coverages with specified gain can be obtained with a set of microstrip circular patch antennas. For the lower stage, a single patch is enough. For geostationary missions, one horizontal array is used, and for heliosynchronous missions two horizontal arrays and a vertical one. The numerical study carried out on omniazimuthal ring antennas shows that a tendency to omnidirectional pattern exists in spite of the directivity of the elementary radiators. A small pointing improvement of the meridian pattern can be obtained by means of conical arrays instead of the cylindrical ones.

  7. Capturing Chromosome Conformation

    NASA Astrophysics Data System (ADS)

    Dekker, Job; Rippe, Karsten; Dekker, Martijn; Kleckner, Nancy

    2002-02-01

    We describe an approach to detect the frequency of interaction between any two genomic loci. Generation of a matrix of interaction frequencies between sites on the same or different chromosomes reveals their relative spatial disposition and provides information about the physical properties of the chromatin fiber. This methodology can be applied to the spatial organization of entire genomes in organisms from bacteria to human. Using the yeast Saccharomyces cerevisiae, we could confirm known qualitative features of chromosome organization within the nucleus and dynamic changes in that organization during meiosis. We also analyzed yeast chromosome III at the G1 stage of the cell cycle. We found that chromatin is highly flexible throughout. Furthermore, functionally distinct AT- and GC-rich domains were found to exhibit different conformations, and a population-average 3D model of chromosome III could be determined. Chromosome III emerges as a contorted ring.

  8. Conformally symmetric relativistic star

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Maharaj, Sunil D.; Sardar, Iftikar Hossain; Chakraborty, Koushik

    2017-03-01

    We investigate whether compact stars having Tolman-like interior geometry admit conformal symmetry. Taking anisotropic pressure along the two principal directions within the compact object, we obtain physically relevant quantities such as transverse and radial pressure, density and redshift function. We study the equation of state (EOS) for the matter distribution inside the star. From the relation between pressure and density function of the constituent matter, we explore the nature and properties of the interior matter. The redshift function and compactness parameter are found to be physically reasonable. The matter inside the star satisfies the null, weak and strong energy conditions. Finally, we compare the masses and radii predicted from the model with corresponding values in some observed stars.

  9. Heparin-dependent regulation of fibronectin matrix conformation

    PubMed Central

    Hubbard, Brant; Buczek-Thomas, Jo Ann; Nugent, Matthew A.; Smith, Michael L.

    2013-01-01

    Extracellular matrix (ECM) conformation is regulated by a variety of stimuli in vivo, including mechanical forces and allosteric binding partners, and these conformational changes contribute to the regulation of cell behavior. Heparin and heparan sulfate, for example, have been shown to regulate the sequestration and presentation of numerous growth factors, including vascular endothelial growth factor, on the heparin 2 binding domain in fibronectin (Fn). However, mechanical force also alters Fn conformation, indicating that the growth factor binding region may be co-regulated by both heparin and mechanical force. Herein, we describe a simple antibody-based method for evaluating the conformation of the heparin 2 binding domain in Fn, and use it to determine the relative contributions of heparin and mechanical strain to the regulation of Fn conformation. We achieved specificity in quantifying conformational changes in this region of Fn by measuring the ratio of two fluorescent monoclonal antibodies, one that is insensitive to Fn conformational changes and a second whose binding is reduced or enhanced by non-equilibrium conformational changes. Importantly, this technique is shown to work on Fn adsorbed on surfaces, single Fn fibers, and Fn matrix fibers in cell culture. Using our dual antibody approach, we show that heparin and mechanical strain co-regulate Fn conformation in matrix fibrils, which is the first demonstration of heparin-dependent regulation of Fn in its physiologically-relevant fibrillar state. Furthermore, the dual antibody approach utilizes commercially available antibodies and simple immunohistochemistry, thus making it accessible to a wide range of scientists interested in Fn mechanobiology. PMID:24148804

  10. De novo protein conformational sampling using a probabilistic graphical model.

    PubMed

    Bhattacharya, Debswapna; Cheng, Jianlin

    2015-11-06

    Efficient exploration of protein conformational space remains challenging especially for large proteins when assembling discretized structural fragments extracted from a protein structure data database. We propose a fragment-free probabilistic graphical model, FUSION, for conformational sampling in continuous space and assess its accuracy using 'blind' protein targets with a length up to 250 residues from the CASP11 structure prediction exercise. The method reduces sampling bottlenecks, exhibits strong convergence, and demonstrates better performance than the popular fragment assembly method, ROSETTA, on relatively larger proteins with a length of more than 150 residues in our benchmark set. FUSION is freely available through a web server at http://protein.rnet.missouri.edu/FUSION/.

  11. Space Robotics

    DTIC Science & Technology

    1982-08-01

    ACCESSION NO 3. RECIPIENTS CATALOG NUIA3.R CMU-RI-TR-82-10 I4 1 (. 4. ;,;-LL (and Sublitle) S. TYPE OF REPORT & PERIOD CovEREO SPACE ROBOTICS Interim... Robotics Institute Pittsburgh, PA. 15213 It. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Office of Naval Research -August 1982 Arlington, VA 22217...SXnet.eE . Space Robotics Richard E. Korf Department of Computer Science and The Robotics Institute Carnegie-Mellon University Pittsburgh, Oetusylvania

  12. Access Denied

    ERIC Educational Resources Information Center

    Villano, Matt

    2008-01-01

    Building access control (BAC)--a catchall phrase to describe the systems that control access to facilities across campus--has traditionally been handled with remarkably low-tech solutions: (1) manual locks; (2) electronic locks; and (3) ID cards with magnetic strips. Recent improvements have included smart cards and keyless solutions that make use…

  13. Open Access

    ERIC Educational Resources Information Center

    Suber, Peter

    2012-01-01

    The Internet lets us share perfect copies of our work with a worldwide audience at virtually no cost. We take advantage of this revolutionary opportunity when we make our work "open access": digital, online, free of charge, and free of most copyright and licensing restrictions. Open access is made possible by the Internet and copyright-holder…

  14. Replacement between conformity and counter-conformity in consumption decisions.

    PubMed

    Chou, Ting-Jui; Chang, En-Chung; Dai, Qi; Wong, Veronica

    2013-02-01

    This study assessed, in a Chinese context, how self-esteem interacts with perceived similarity and uniqueness to yield cognitive dissonance, and whether the dissonance leads to self-reported conformity or counter-conformity behavior. Participants were 408 respondents from 4 major Chinese cities (M age = 33.0 yr., SD = 4.3; 48% men). Self-perceptions of uniqueness, similarity, cognitive dissonance, self-esteem and need to behave in conformity or counter-conformity were measured. A theoretical model was assessed in four situations, relating the ratings of self-esteem and perceived similarity/uniqueness to the way other people at a wedding were dressed, and the resultant cognitive dissonance and conformity/ counter-conformity behavior. Regardless of high or low self-esteem, all participants reported cognitive dissonance when they were told that they were dressed extremely similarly to or extremely differently from the other people attending the wedding. However, the conforming/counter-conforming strategies used by participants to resolve the cognitive dissonance differed. When encountering dissonance induced by the perceived extreme uniqueness of dress, participants with low self-esteem tended to say they would dress next time so as to conform with the way others were dressed, while those with high self-esteem indicated they would continue their counter-conformity in attire. When encountering dissonance induced by the perceived extreme similarity to others, both those with high and low self-esteem tended to say they would dress in an unorthodox manner to surprise other people in the future.

  15. Conformational Entropy of Intrinsically Disordered Proteins from Amino Acid Triads

    PubMed Central

    Baruah, Anupaul; Rani, Pooja; Biswas, Parbati

    2015-01-01

    This work quantitatively characterizes intrinsic disorder in proteins in terms of sequence composition and backbone conformational entropy. Analysis of the normalized relative composition of the amino acid triads highlights a distinct boundary between globular and disordered proteins. The conformational entropy is calculated from the dihedral angles of the middle amino acid in the amino acid triad for the conformational ensemble of the globular, partially and completely disordered proteins relative to the non-redundant database. Both Monte Carlo (MC) and Molecular Dynamics (MD) simulations are used to characterize the conformational ensemble of the representative proteins of each group. The results show that the globular proteins span approximately half of the allowed conformational states in the Ramachandran space, while the amino acid triads in disordered proteins sample the entire range of the allowed dihedral angle space following Flory’s isolated-pair hypothesis. Therefore, only the sequence information in terms of the relative amino acid triad composition may be sufficient to predict protein disorder and the backbone conformational entropy, even in the absence of well-defined structure. The predicted entropies are found to agree with those calculated using mutual information expansion and the histogram method. PMID:26138206

  16. Bi-conformal vector fields and their applications

    NASA Astrophysics Data System (ADS)

    García-Parrado, Alfonso; Senovilla, JosA~© M. M.

    2004-04-01

    We introduce a concept of bi-conformal transformation, as a generalization of conformal ones, by allowing two orthogonal parts of a manifold with metric g to be scaled by different conformal factors. In particular, we study their infinitesimal version, called bi-conformal vector fields. We show that these are characterized by the differential conditions {{\\pounds}_{{\\vec{{\\bm \\xi}}}}} {\\bf P}\\propto {\\bf P} and {{\\pounds}_{{\\vec{{\\bm \\xi}}}}} {\\bm \\Pi} \\propto {\\bm \\Pi} , where P and Π are orthogonal projectors (P + Π = g). Keeping P and Π fixed, the set of bi-conformal vector fields is a Lie algebra which can be finite or infinite dimensional according to the dimensionality of the projectors. We determine (i) when an infinite-dimensional case is feasible and its properties, and (ii) a normal system for the generators in the finite-dimensional case. Its integrability conditions are also analysed, which in particular provides the maximum number of linearly independent solutions. We identify the corresponding maximal spaces, and show a necessary geometric condition for a metric tensor to be a double-twisted product. More general 'breakable' spaces are briefly considered. Many known symmetries are included, such as conformal Killing vectors, Kerr Schild vector fields, kinematic self-similarity, causal symmetries and rigid motions.

  17. Counselor Identity: Conformity or Distinction?

    ERIC Educational Resources Information Center

    McLaughlin, Jerry E.; Boettcher, Kathryn

    2009-01-01

    The authors explore 3 debates in other disciplines similar to counseling's identity debate in order to learn about common themes and outcomes. Conformity, distinction, and cohesion emerged as common themes. They conclude that counselors should retain their distinctive, humanistic approach rather than conforming to the dominant, medical approach.

  18. Conformational preferences of 3,4-dihydroxyphenylacetic acid (DOPAC)

    NASA Astrophysics Data System (ADS)

    Lopes Jesus, A. J.; Jarmelo, S.; Fausto, R.; Reva, I.

    2015-04-01

    The conformational space of 3,4-dihydroxyphenylacetic acid (DOPAC), an important dopamine metabolite, has been investigated by quantum chemical methods (B3LYP and MP2, with the 6-311++G(d,p) basis set) and matrix-isolation infrared spectroscopy. Detailed analysis of the calculated potential energy surfaces of the molecule led to identification of thirteen unique conformers, all of them showing the acetic acid side chain out of the aromatic ring plane by 60-95°. According to the calculated Gibbs energies, the five lowest energy conformers make up 99.7% of the conformational mixture at 298.15 K, exhibiting individual populations falling between 16% and 24%. The main conformational trends of this molecule were interpreted on the grounds of a thorough analysis of the structural parameters and by the application of the Natural Bond Orbital theory. The role of the intramolecular interactions on the relative stability and structure of the conformers was also investigated. The infrared spectrum of DOPAC was registered after isolation of its monomers in argon and xenon matrices. Only one of DOPAC forms populated in the gas phase could be trapped in both matrix gases. This result is in agreement with the predicted low energy barriers for conformational isomerization and is also supported by annealing experiments. The spectra of matrix-isolated model compounds, phenylacetic acid and catechol, were studied under the same experimental conditions. These data were used as references and assisted in the interpretation of the results obtained for DOPAC.

  19. HL-20 structural design comparison - Conformal shell versus cylindrical crew compartment

    NASA Astrophysics Data System (ADS)

    Bush, Lance B.; Wahls, Deborah M.; Robinson, James C.

    1993-04-01

    Extensive studies have been performed at NASA Langley Research Center (LaRC) on personnel launch systems (PLS) concepts. The primary mission of a PLS is the transport of Space Station crew members from Earth to the Space Station and return. The NASA LaRC PLS studies have led to the design of a lifting body configuration named the HL-20. In this study, two different HL-20 structural configurations are evaluated. The two configurations are deemed the conformal shell and the cylindrical crew compartment. The configurations are based on two different concerns for maintenance and operations. One configuration allows for access to subsystems while on-orbit from the interior, while the other allows for easy access to the subsystems during ground maintenance and operations. For each concept, the total structural weight required to sustain the applied loads is quantified through a structural evaluation. Structural weight for both configurations is compared along with the particular attributes of each. Analyses of both configurations indicate no appreciable weight or load relief advantage of one concept over the other. Maintainability and operability, therefore become the primary discriminator, leading to a choice of a crew compartment configuration.

  20. HL-20 structural design comparison - Conformal shell versus cylindrical crew compartment

    NASA Technical Reports Server (NTRS)

    Bush, Lance B.; Wahls, Deborah M.; Robinson, James C.

    1993-01-01

    Extensive studies have been performed at NASA Langley Research Center (LaRC) on personnel launch systems (PLS) concepts. The primary mission of a PLS is the transport of Space Station crew members from Earth to the Space Station and return. The NASA LaRC PLS studies have led to the design of a lifting body configuration named the HL-20. In this study, two different HL-20 structural configurations are evaluated. The two configurations are deemed the conformal shell and the cylindrical crew compartment. The configurations are based on two different concerns for maintenance and operations. One configuration allows for access to subsystems while on-orbit from the interior, while the other allows for easy access to the subsystems during ground maintenance and operations. For each concept, the total structural weight required to sustain the applied loads is quantified through a structural evaluation. Structural weight for both configurations is compared along with the particular attributes of each. Analyses of both configurations indicate no appreciable weight or load relief advantage of one concept over the other. Maintainability and operability, therefore become the primary discriminator, leading to a choice of a crew compartment configuration.

  1. Selective access and editing in a database

    NASA Technical Reports Server (NTRS)

    Maluf, David A. (Inventor); Gawdiak, Yuri O. (Inventor)

    2010-01-01

    Method and system for providing selective access to different portions of a database by different subgroups of database users. Where N users are involved, up to 2.sup.N-1 distinguishable access subgroups in a group space can be formed, where no two access subgroups have the same members. Two or more members of a given access subgroup can edit, substantially simultaneously, a document accessible to each member.

  2. Unitary Fermi Gas, ɛ Expansion, and Nonrelativistic Conformal Field Theories

    NASA Astrophysics Data System (ADS)

    Nishida, Yusuke; Son, Dam Thanh

    We review theoretical aspects of unitary Fermi gas (UFG), which has been realized in ultracold atom experiments. We first introduce the ɛ expansion technique based on a systematic expansion in terms of the dimensionality of space. We apply this technique to compute the thermodynamic quantities, the quasiparticle cum, and the criticl temperature of UFG. We then discuss consequences of the scale and conformal invariance of UFG. We prove a correspondence between primary operators in nonrelativistic conformal field theories and energy eigenstates in a harmonic potential. We use this correspondence to compute energies of fermions at unitarity in a harmonic potential. The scale and conformal invariance together with the general coordinate invariance constrains the properties of UFG. We show the vanishing bulk viscosities of UFG and derive the low-energy effective Lagrangian for the superfluid UFG. Finally we propose other systems exhibiting the nonrelativistic scaling and conformal symmetries that can be in principle realized in ultracold atom experiments.

  3. In silico Exploration of the Conformational Universe of GPCRs.

    PubMed

    Rodríguez-Espigares, Ismael; Kaczor, Agnieszka A; Selent, Jana

    2016-07-01

    The structural plasticity of G protein coupled receptors (GPCRs) leads to a conformational universe going from inactive to active receptor states with several intermediate states. Many of them have not been captured yet and their role for GPCR activation is not well understood. The study of this conformational space and the transition dynamics between different receptor populations is a major challenge in molecular biophysics. The rational design of effector molecules that target such receptor populations allows fine-tuning receptor signalling with higher specificity to produce drugs with safer therapeutic profiles. In this minireview, we outline highly conserved receptor regions which are considered determinant for the establishment of distinct receptor states. We then discuss in-silico approaches such as dimensionality reduction methods and Markov State Models to explore the GPCR conformational universe and exploit the obtained conformations through structure-based drug design.

  4. Solidifying Small Satellite Access to Orbit via the International Space Station (ISS): Cyclops' Deployment of the Lonestar SmallSat from the ISS

    NASA Technical Reports Server (NTRS)

    Hershey, Matthew P.; Newswander, Daniel R.; Evernden, Brent A.

    2016-01-01

    On January 29, 2016, the Space Station Integrated Kinetic Launcher for Orbital Payload Systems (SSIKLOPS), known as "Cyclops" to the International Space Station (ISS) community, deployed Lonestar from the ISS. The deployment of Lonestar, a collaboration between Texas A&M University and the University of Texas at Austin, continued to showcase the simplicity and reliability of the Cyclops deployment system. Cyclops, a NASA-developed, dedicated 10-100 kg class ISS SmallSat deployment system, utilizes the Japanese airlock and robotic systems to seamlessly insert SmallSats into orbit. This paper will illustrate Cyclops' successful deployment of Lonestar from the ISS as well as outline its concept of operations, interfaces, requirements, and processes.

  5. Conformal current algebra in two dimensions

    NASA Astrophysics Data System (ADS)

    Ashok, Sujay K.; Benichou, Raphael; Troost, Jan

    2009-06-01

    We construct a non-chiral current algebra in two dimensions consistent with conformal invariance. We show that the conformal current algebra is realized in non-linear sigma-models on supergroup manifolds with vanishing Killing form, with or without a Wess-Zumino term. The current algebra is computed using two distinct methods. First we exploit special algebraic properties of supergroups to compute the exact two- and three-point functions of the currents and from them we infer the current algebra. The algebra is also calculated by using conformal perturbation theory about the Wess-Zumino-Witten point and resumming the perturbation series. We also prove that these models realize a non-chiral Kac-Moody algebra and construct an infinite set of commuting operators that is closed under the action of the Kac-Moody generators. The supergroup models that we consider include models with applications to statistical mechanics, condensed matter and string theory. In particular, our results may help to systematically solve and clarify the quantum integrability of PSU(n|n) models and their cosets, which appear prominently in string worldsheet models on anti-deSitter spaces.

  6. Conformal gravity and “gravitational bubbles”

    NASA Astrophysics Data System (ADS)

    Berezin, V. A.; Dokuchaev, V. I.; Eroshenko, Yu. N.

    2016-01-01

    We describe the general structure of the spherically symmetric solutions in the Weyl conformal gravity. The corresponding Bach equations are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions, consisting of two classes, is found. The first one contains the solutions with constant two-dimensional curvature scalar, and the representatives are the famous Robertson-Walker metrics. We called one of them the “gravitational bubbles”, which is compact and with zero Weyl tensor. These “gravitational bubbles” are the pure vacuum curved space-times (without any material sources, including the cosmological constant), which are absolutely impossible in General Relativity. This phenomenon makes it easier to create the universe from “nothing”. The second class consists of the solutions with varying curvature scalar. We found its representative as the one-parameter family, which can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We describe the general structure of the energy-momentum tensor in the spherical conformal gravity and construct the vectorial equation that reveals clearly some features of non-vacuum solutions.

  7. Dynamics of protein conformations

    NASA Astrophysics Data System (ADS)

    Stepanova, Maria

    2010-10-01

    A novel theoretical methodology is introduced to identify dynamic structural domains and analyze local flexibility in proteins. The methodology employs a multiscale approach combining identification of essential collective coordinates based on the covariance analysis of molecular dynamics trajectories, construction of the Mori projection operator with these essential coordinates, and analysis of the corresponding generalized Langevin equations [M.Stepanova, Phys.Rev.E 76(2007)051918]. Because the approach employs a rigorous theory, the outcomes are physically transparent: the dynamic domains are associated with regions of relative rigidity in the protein, whereas off-domain regions are relatively soft. This also allows scoring the flexibility in the macromolecule with atomic-level resolution [N.Blinov, M.Berjanskii, D.S.Wishart, and M.Stepanova, Biochemistry, 48(2009)1488]. The applications include the domain coarse-graining and characterization of conformational stability in protein G and prion proteins. The results are compared with published NMR experiments. Potential applications for structural biology, bioinformatics, and drug design are discussed.

  8. Imaging of conformational changes

    SciTech Connect

    Michl, Josef

    2016-03-13

    Control of intramolecular conformational change in a small number of molecules or even a single one by an application of an outside electric field defined by potentials on nearby metal or dielectric surfaces has potential applications in both 3-D and 2-D nanotechnology. Specifically, the synthesis, characterization, and understanding of designed solids with controlled built-in internal rotational motion of a dipole promises a new class of materials with intrinsic dielectric, ferroelectric, optical and optoelectronic properties not found in nature. Controlled rotational motion is of great interest due to its expected utility in phenomena as diverse as transport, current flow in molecular junctions, diffusion in microfluidic channels, and rotary motion in molecular machines. A direct time-resolved observation of the dynamics of motion on ps or ns time scale in a single molecule would be highly interesting but is also very difficult and has yet to be accomplished. Much can be learned from an easier but still challenging comparison of directly observed initial and final orientational states of a single molecule, which is the basis of this project. The project also impacts the understanding of surface-enhanced Raman spectroscopy (SERS) and single-molecule spectroscopic detection, as well as the synthesis of solid-state materials with tailored properties from designed precursors.

  9. Conformal Fermi Coordinates

    SciTech Connect

    Dai, Liang; Pajer, Enrico; Schmidt, Fabian E-mail: Enrico.pajer@gmail.com

    2015-11-01

    Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally observable, physical effects of a long-wavelength spacetime perturbation. Their cosmological application, however, is hampered by the fact that they are only valid on scales much smaller than the horizon. We introduce a generalization that we call Conformal Fermi Coordinates (CFC). CFC preserve all the advantages of FNC, but in addition are valid outside the horizon. They allow us to calculate the coupling of long- and short-wavelength modes on all scales larger than the sound horizon of the cosmological fluid, starting from the epoch of inflation until today, by removing the complications of the second order Einstein equations to a large extent, and eliminating all gauge ambiguities. As an application, we present a calculation of the effect of long-wavelength tensor modes on small scale density fluctuations. We recover previous results, but clarify the physical content of the individual contributions in terms of locally measurable effects and ''projection'' terms.

  10. Remarks on Polyelectrolyte Conformation

    NASA Astrophysics Data System (ADS)

    de Gennes, P. G.; Pincus, P.; Velasco, R. M.; Brochard, F.

    Nous discutons des conformations de polymères linéaires chargés en faisant les hypothèses suivantes : a) la chaĬne sans charge est flexible, b) la force éctrostatique domine les interactions monomère-monomère c) il n'y a pas de sels. 1) Pour le cas dilué (chaĬne non enchevetrees) en corrigeant le calcul self-consistant fait récemment par Richmond [1a], on trouve une taille des polyions égale a = R ND, qui est une fonction linéaire de l'indice de polymérisation N. Ce rèsultat est en accord avec les prècèdents travaux de Hermans et Overbeek [1b], Kuhn, Kunzle et Katchalsky [1c]. 2) Il existe un domaine pour des concentrations très petites c (c** < c < c*) oò les interactions èlectrostatiques entre les polyions sont supèrieures aux ènergies thermiques, il semble donc possible que les polyions puissent former un rèseau pèriodique à trois dimensions. Nèanmoins, il semble difficile de mettre en èvidence un rèseau si diluè. 3) Jusqu'ici toutes les expériences avec les polyélectrolytes sans sels ont été pratiquement faites à des concentrations c > c*, pour lesquelles les différentes cha.nes sont enchevêtrées. Pour discuter ce régime on s.intéresse uniquement au cas où la charge par unité de longueur est près du (ou audessus du) seuil de condensation, donc il existe une seule longueur ξ(c) caractérisant les corrélations; à trois dimensions 03BE a le même comportement que le rayon de Debye pour les contre-ions. On a considéré quelques conformations possibles : a) un réseau hexagonal de batonnets; b) un réseau cubique de batonnets; c) une phase isotrope de cha.nes partiellement flexibles. Les différentes structures formées de batonnets semblent avoir la même énergie électrostatique. Ce fait suggère que la phase isotrope peut être la plus favorable. On analyse cette dernière phase en utilisant les mêmes méthodes qui se sont révélées efficaces pour les solutions des polymères neutres. Dans le modèle isotrope

  11. Conformal Ablative Thermal Protection System for Planetary and Human Exploration Missions:An Overview of the Technology Maturation Effort

    NASA Technical Reports Server (NTRS)

    Beck, Robin A S.; Arnold, James O.; Gasch, Matthew J.; Stackpoole, Margaret M.; Prabhu, Dinesh K.; Szalai, Christine E.; Wercinski, Paul F.; Venkatapathy, Ethiraj

    2013-01-01

    The Office of Chief Technologist, NASA identified the need for research and technology development in part from NASAs Strategic Goal 3.3 of the NASA Strategic Plan to develop and demonstrate the critical technologies that will make NASAs exploration, science, and discovery missions more affordable and more capable. Furthermore, the Game Changing Development Program is a primary avenue to achieve the Agencys 2011 strategic goal to Create the innovative new space technologies for our exploration, science, and economic future. The National Research Council (NRC) Space Technology Roadmaps and Priorities report highlights six challenges and they are: Mass to Surface, Surface Access, Precision Landing, Surface Hazard Detection and Avoidance, Safety and Mission Assurance, and Affordability. In order for NASA to meet these challenges, the report recommends immediate focus on Rigid and Flexible Thermal Protection Systems. Rigid TPS systems such as Avcoat or SLA are honeycomb based and PICA is in the form of tiles. The honeycomb systems are manufactured using techniques that require filling of each (38 cell) by hand, and in a limited amount of time all of the cells must be filled and the heatshield must be cured. The tile systems such as PICA pose a different challenge as the low strain-to-failure and manufacturing size limitations require large number of small tiles with gap-fillers between the tiles. Recent investments in flexible ablative systems have given rise to the potential for conformal ablative TPS. A conformal TPS over a rigid aeroshell has the potential to solve a number of challenges faced by traditional rigid TPS materials. The high strain-to-failure nature of the conformal ablative materials will allow integration of the TPS with the underlying aeroshell structure much easier and enable monolithic-like configuration and larger segments (or parts) to be used. By reducing the overall part count, the cost of installation (based on cost comparisons between blanket

  12. [An application of low-invasive access in ultrasound-guided surgery of liquid formation of the abdominal cavity and retroperitoneal space].

    PubMed

    Demin, D B; Laĭkov, A V; Funygin, M S; Chegodaeva, A A; Solodov, Iu Iu; Butina, K V

    2014-01-01

    The article presents a low-invasive method in the intraoperative ultrasound-guided surgery. The method had several steps: an access (2-3 cm) was made to a liquid formation with the following aspiration of contents, a necrotic detritus was removed through the wound tract using simultaneous ultrasound examination of efficacy of emptying the cavity with drainage. This means allowed the performance of single-stage sanitization and drainage of cavity formations, which contained the liquid and dense necrotic tissues in the lumen. The method was effective, technically workable in any surgical hospital. At the same time, it was economically reasonable, because there wasn't need to buy an additional equipment. The application of the means considerably shortened a hospital stay and the lethality was reduced.

  13. Equal Access.

    ERIC Educational Resources Information Center

    De Patta, Joe

    2003-01-01

    Presents an interview with Stephen McCarthy, co-partner and president of Equal Access ADA Consulting Architects of San Diego, California, about designing schools to naturally integrate compliance with the Americans with Disabilities Act (ADA). (EV)

  14. Conformation and Aggregation of LKα14 Peptide in Bulk Water and at the Air/Water Interface.

    PubMed

    Dalgicdir, Cahit; Sayar, Mehmet

    2015-12-10

    Historically, the protein folding problem has mainly been associated with understanding the relationship between amino acid sequence and structure. However, it is known that both the conformation of individual molecules and their aggregation strongly depend on the environmental conditions. Here, we study the aggregation behavior of the model peptide LKα14 (with amino acid sequence LKKLLKLLKKLLKL) in bulk water and at the air/water interface. We start by a quantitative analysis of the conformational space of a single LKα14 in bulk water. Next, in order to analyze the aggregation tendency of LKα14, by using the umbrella sampling technique we calculate the potential of mean force for pulling a single peptide from an n-molecule aggregate. In agreement with the experimental results, our calculations yield the optimal aggregate size as four. This equilibrium state is achieved by two opposing forces: Coulomb repulsion between the lysine side chains and the reduction of solvent accessible hydrophobic surface area upon aggregation. At the vacuum/water interface, however, even dimers of LKα14 become marginally stable, and any larger aggregate falls apart instantaneously. Our results indicate that even though the interface is highly influential in stabilizing the α-helix conformation for a single molecule, it significantly reduces the attraction between two LKα14 peptides, along with their aggregation tendency.

  15. Conformational Changes Represent the Rate-Limiting Step in the Transport Cycle of Maize SUCROSE TRANSPORTER1[C][W

    PubMed Central

    Derrer, Carmen; Wittek, Anke; Bamberg, Ernst; Carpaneto, Armando; Dreyer, Ingo; Geiger, Dietmar

    2013-01-01

    Proton-driven Suc transporters allow phloem cells of higher plants to accumulate Suc to more than 1 M, which is up to ∼1000-fold higher than in the surrounding extracellular space. The carrier protein can accomplish this task only because proton and Suc transport are tightly coupled. This study provides insights into this coupling by resolving the first step in the transport cycle of the Suc transporter SUT1 from maize (Zea mays). Voltage clamp fluorometry measurements combining electrophysiological techniques with fluorescence-based methods enable the visualization of conformational changes of SUT1 expressed in Xenopus laevis oocytes. Using the Suc derivate sucralose, binding of which hinders conformational changes of SUT1, the association of protons to the carrier could be dissected from transport-associated movements of the protein. These combined approaches enabled us to resolve the binding of protons to the carrier and its interrelationship with the alternating movement of the protein. The data indicate that the rate-limiting step of the reaction cycle is determined by the accessibility of the proton binding site. This, in turn, is determined by the conformational change of the SUT1 protein, alternately exposing the binding pockets to the inward and to the outward face of the membrane. PMID:23964025

  16. A method for correlations analysis of coordinates: applications for molecular conformations.

    PubMed

    Chema, Doron; Becker, Oren M

    2002-01-01

    We describe a new method to analyze multiple correlations between subsets of coordinates that represent a sample. The correlation is established only between specific regions of interest at the coordinates. First, the region(s) of interest are selected at each molecular coordinate. Next, a correlation matrix is constructed for the selected regions. The matrix is subject to further analysis, illuminating the multidimensional structural characteristics that exist in the conformational space. The method's abilities are demonstrated in several examples: it is used to analyze the conformational space of complex molecules, it is successfully applied to compare related conformational spaces, and it is used to analyze a diverse set of protein folding trajectories.

  17. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2002-02-28

    This technical progress report describes work performed from June 20 through December 19, 2001, for the project, ''Conformance Improvement Using Gels''. Interest has increased in some new polymeric products that purport to substantially reduce permeability to water while causing minimum permeability reduction to oil. In view of this interest, we are currently studying BJ's Aqua Con. Results from six corefloods revealed that the Aqua Con gelant consistently reduced permeability to water more than that to oil. However, the magnitude of the disproportionate permeability reduction varied significantly for the various experiments. Thus, as with most materials tested to date, the issue of reproducibility and control of the disproportionate permeability remains to be resolved. Concern exists about the ability of gels to resist washout after placement in fractures. We examined whether a width constriction in the middle of a fracture would cause different gel washout behavior upstream versus downstream of the constriction. Tests were performed using a formed Cr(III)-acetate-HPAM gel in a 48-in.-long fracture with three sections of equal length, but with widths of 0.08-, 0.02-, and 0.08-in., respectively. The pressure gradients during gel extrusion (i.e., placement) were similar in the two 0.08-in.-wide fracture sections, even though they were separated by a 0.02-in.-wide fracture section. The constriction associated with the middle fracture section may have inhibited gel washout during the first pulse of brine injection after gel placement. However, during subsequent phases of brine injection, the constriction did not inhibit washout in the upstream fracture section any more than in the downstream section.

  18. Analysis of Conformational B-Cell Epitopes in the Antibody-Antigen Complex Using the Depth Function and the Convex Hull.

    PubMed

    Zheng, Wei; Ruan, Jishou; Hu, Gang; Wang, Kui; Hanlon, Michelle; Gao, Jianzhao

    2015-01-01

    The prediction of conformational b-cell epitopes plays an important role in immunoinformatics. Several computational methods are proposed on the basis of discrimination determined by the solvent-accessible surface between epitopes and non-epitopes, but the performance of existing methods is far from satisfying. In this paper, depth functions and the k-th surface convex hull are used to analyze epitopes and exposed non-epitopes. On each layer of the protein, we compute relative solvent accessibility and four different types of depth functions, i.e., Chakravarty depth, DPX, half-sphere exposure and half space depth, to analyze the location of epitopes on different layers of the proteins. We found that conformational b-cell epitopes are rich in charged residues Asp, Glu, Lys, Arg, His; aliphatic residues Gly, Pro; non-charged residues Asn, Gln; and aromatic residue Tyr. Conformational b-cell epitopes are rich in coils. Conservation of epitopes is not significantly lower than that of exposed non-epitopes. The average depths (obtained by four methods) for epitopes are significantly lower than that of non-epitopes on the surface using the Wilcoxon rank sum test. Epitopes are more likely to be located in the outer layer of the convex hull of a protein. On the benchmark dataset, the cumulate 10th convex hull covers 84.6% of exposed residues on the protein surface area, and nearly 95% of epitope sites. These findings may be helpful in building a predictor for epitopes.

  19. Predicting conformational switches in proteins.

    PubMed Central

    Young, M.; Kirshenbaum, K.; Dill, K. A.; Highsmith, S.

    1999-01-01

    We describe a new computational technique to predict conformationally switching elements in proteins from their amino acid sequences. The method, called ASP (Ambivalent Structure Predictor), analyzes results from a secondary structure prediction algorithm to identify regions of conformational ambivalence. ASP identifies ambivalent regions in 16 test protein sequences for which function involves substantial backbone rearrangements. In the test set, all sites previously described as conformational switches are correctly predicted to be structurally ambivalent regions. No such regions are predicted in three negative control protein sequences. ASP may be useful as a guide for experimental studies on protein function and motion in the absence of detailed three-dimensional structural data. PMID:10493576

  20. Conformational changes of adsorbed proteins

    NASA Astrophysics Data System (ADS)

    Allen, Scott

    2005-03-01

    The adsorption of bovine serum albumin (BSA) and pepsin to gold surfaces has been studied using surface plasmon resonance (SPR). Proteins are adsorbed from solution onto a gold surface and changes in the conformation of the adsorbed proteins are induced by changing the buffer solution. We selected pH and ionic strength values for the buffer solutions that are known from our circular dichroism measurements to cause conformational changes of the proteins in bulk solution. We find that for both BSA and pepsin the changes in conformation are impeded by the interaction of the protein with the gold surface.

  1. Conformal tensors via Lovelock gravity

    NASA Astrophysics Data System (ADS)

    Kastor, David

    2013-10-01

    Constructs from conformal geometry are important in low dimensional gravity models, while in higher dimensions the higher curvature interactions of Lovelock gravity are similarly prominent. Considering conformal invariance in the context of Lovelock gravity leads to natural, higher curvature generalizations of the Weyl, Schouten, Cotton and Bach tensors, with properties that straightforwardly extend those of their familiar counterparts. As a first application, we introduce a new set of conformally invariant gravity theories in D = 4k dimensions, based on the squares of the higher curvature Weyl tensors.

  2. A molecular modeling approach to understand the structure and conformation relationship of (GlcpA)Xylan.

    PubMed

    Guo, Qingbin; Kang, Ji; Wu, Yan; Cui, Steve W; Hu, Xinzhong; Yada, Rickey Y

    2015-12-10

    The structure and conformation relationships of a heteropolysaccharide (GlcpA)Xylan in terms of various molecular weights, Xylp/GlcpA ratio and the distribution of GlcpA along xylan chain were investigated using computer modeling. The adiabatic contour maps of xylobiose, XylpXylp(GlcpA) and (GlcpA)XylpXylp(GlcpA) indicated that the insertion of the side group (GlcpA) influenced the accessible conformational space of xylobiose molecule. RIS-Metropolis Monte Carlo method indicated that insertion of GlcpA side chain induced a lowering effect of the calculated chain extension at low GlcpA:Xylp ratio (GlcpA:Xylp = 1:3). The chain, however, became extended when the ratio of GlcpA:Xylp above 2/3. It was also shown that the spatial extension of the polymer chains was dependent on the distribution of side chain: the random distribution demonstrated the most flexible structure compared to block and alternative distribution. The present studies provide a unique insight into the dependence of both side chain ratio and distribution on the stiffness and flexibility of various (GlcpA)Xylan molecules.

  3. Conformational Landscape of Nicotinoids: Solving the "conformational - Rity" of Anabasine

    NASA Astrophysics Data System (ADS)

    Lesarri, Alberto; Cocinero, Emilio J.; Evangelisti, Luca; Suenram, Richard D.; Caminati, Walther; Grabow, Jens-Uwe

    2010-06-01

    The conformational landscape of the alkaloid anabasine (neonicotine) has been investigated using rotational spectroscopy and ab initio calculations. The results allow a detailed comparison of the structural properties of the prototype piperidinic and pyrrolidinic nicotinoids (anabasine vs. nicotine). Anabasine adopts two most stable conformations in isolation conditions, for which we determined accurate rotational and nuclear quadrupole coupling parameters. The preferred conformations are characterized by an equatorial pyridine moiety and additional N-H equatorial stereochemistry at the piperidine ring (Eq-Eq). The two rings of anabasine are close to a bisecting arrangement, with the observed conformations differing in a ca. 180° rotation of the pyridine subunit, denoted either Syn or Anti. The preference of anabasine for the Eq-Eq-Syn conformation has been established by relative intensity measurements (Syn/Anti˜5(2)). The conformational preferences of free anabasine are directed by a N\\cdot\\cdot\\cdotH-C weak hydrogen bond interaction between the nitrogen lone pair at piperidine and the closest hydrogen bond in pyridine, with N\\cdot\\cdot\\cdotN distances ranging from 4.750 Å (Syn) to 4.233 Å (Anti). R. J. Lavrich, R. D. Suenram, D. F. Plusquellic and S. Davis, 58^th OSU Int. Symp. on Mol. Spectrosc., Columbus, OH, 2003, Comm. RH13.

  4. Null conformal Killing-Yano tensors and Birkhoff theorem

    NASA Astrophysics Data System (ADS)

    Ferrando, Joan Josep; Sáez, Juan Antonio

    2016-04-01

    We study the space-times admitting a null conformal Killing-Yano tensor whose divergence defines a Killing vector. We analyze the similarities and differences with the recently studied non null case (Ferrando and Sáez in Gen Relativ Gravit 47:1911, 2015). The results by Barnes concerning the Birkhoff theorem for the case of null orbits are analyzed and generalized.

  5. Characterization of DNA conformation inside bacterial viruses

    NASA Astrophysics Data System (ADS)

    Petrov, Anton S.; Locker, C. Rebecca; Harvey, Stephen C.

    2009-08-01

    In this study we develop a formalism to describe the organization of DNA inside bacteriophage capsids during genome packaging. We have previously shown that DNA inside bacteriophage phi29 (ϕ29) is organized into folded toroids [A. S. Petrov and S. C. Harvey, Structure 15, 21 (2007)], whereas epsilon15 (ɛ15) reveals the coaxial organization of the genetic material [A. S. Petrov, K. Lim-Hing, and S. C. Harvey, Structure 15, 807 (2007)]. We now show that each system undergoes two consecutive transitions. The first transition corresponds to the formation of global conformations and is analogous to a disorder-order conformational transition. The second transition is characterized by a significant loss of DNA mobility at the local level leading to glasslike dynamic behavior. Packing genetic material inside bacteriophages can be used as a general model to study the behavior of semiflexible chains inside confined spaces, and the proposed formalism developed here can be used to study other systems of linear polymer chains confined to closed spaces.

  6. Lipids modulate the conformational dynamics of a secondary multidrug transporter

    PubMed Central

    Martens, Chloé; Stein, Richard A; Masureel, Matthieu; Roth, Aurélie; Mishra, Smriti; Dawaliby, Rosie; Konijnenberg, Albert; Sobott, Frank; Govaerts, Cédric; Mchaourab, Hassane S

    2017-01-01

    Direct interactions with lipids have emerged as key determinants of the folding, structure and function of membrane proteins, but an understanding of how lipids modulate protein dynamics is still lacking. Here, we systematically explored the effects of lipids on the conformational dynamics of the proton-powered, multidrug transporter LmrP from Lactococcus lactis utilizing the pattern of distances between spin label pairs previously shown to fingerprint alternating access of the protein. We uncover at the molecular level how the lipid headgroups shape the conformational energy landscape of the transporter. The model emerging from our data hypothesizes a direct interaction between lipid headgroups and a conserved motif of charged residues that control the conformational equilibrium through an interplay of electrostatic interactions within the protein. Together, our data lay the foundation for a comprehensive model of secondary multidrug transport in lipid bilayers. PMID:27399258

  7. Conformity Adequacy Review: Region 5

    EPA Pesticide Factsheets

    Resources are for air quality and transportation government and community leaders. Information on the conformity SIP adequacy/inadequacy of state implementation plans (SIPs) in EPA Region 5 (IL, IN, MI, OH, WI) is provided here.

  8. Graphene-based conformal devices.

    PubMed

    Park, Yong Ju; Lee, Seoung-Ki; Kim, Min-Seok; Kim, Hyunmin; Ahn, Jong-Hyun

    2014-08-26

    Despite recent progress in bendable and stretchable thin-film transistors using novel designs and materials, the development of conformal devices remains limited by the insufficient flexibility of devices. Here, we demonstrate the fabrication of graphene-based conformal and stretchable devices such as transistor and tactile sensor on a substrate with a convoluted surface by scaling down the device thickness. The 70 nm thick graphene-based conformal devices displayed a much lower bending stiffness than reported previously. The demonstrated devices provided excellent conformal coverage over an uneven animal hide surface without the need for an adhesive. In addition, the ultrathin graphene devices formed on the three-dimensionally curved animal hide exhibited stable electrical characteristics, even under repetitive bending and twisting. The advanced performance and flexibility demonstrated here show promise for the development and adoption of wearable electronics in a wide range of future applications.

  9. Conformation Distributions in Adsorbed Proteins.

    NASA Astrophysics Data System (ADS)

    Meuse, Curtis W.; Hubbard, Joseph B.; Vrettos, John S.; Smith, Jackson R.; Cicerone, Marcus T.

    2007-03-01

    While the structural basis of protein function is well understood in the biopharmaceutical and biotechnology industries, few methods for the characterization and comparison of protein conformation distributions are available. New methods capable of measuring the stability of protein conformations and the integrity of protein-protein, protein-ligand and protein-surface interactions both in solution and on surfaces are needed to help the development of protein-based products. We are developing infrared spectroscopy methods for the characterization and comparison of molecular conformation distributions in monolayers and in solutions. We have extracted an order parameter describing the orientational and conformational variations of protein functional groups around the average molecular values from a single polarized spectrum. We will discuss the development of these methods and compare them to amide hydrogen/deuterium exchange methods for albumin in solution and on different polymer surfaces to show that our order parameter is related to protein stability.

  10. Lattice Simulations and Infrared Conformality

    DOE PAGES

    Appelquist, Thomas; Fleming, George T.; Lin, Meifeng; ...

    2011-09-01

    We examine several recent lattice-simulation data sets, asking whether they are consistent with infrared conformality. We observe, in particular, that for an SU(3) gauge theory with 12 Dirac fermions in the fundamental representation, recent simulation data can be described assuming infrared conformality. Lattice simulations include a fermion mass m which is then extrapolated to zero, and we note that this data can be fit by a small-m expansion, allowing a controlled extrapolation. We also note that the conformal hypothesis does not work well for two theories that are known or expected to be confining and chirally broken, and that itmore » does work well for another theory expected to be infrared conformal.« less

  11. Conformal mapping of rectangular heptagons

    SciTech Connect

    Bogatyrev, Andrei B

    2012-12-31

    A new effective approach to calculating the direct and inverse conformal mapping of rectangular polygons onto a half-plane is put forward; it is based on the use of Riemann theta functions. Bibliography: 14 titles.

  12. Solution NMR conformation of glycosaminoglycans.

    PubMed

    Pomin, Vitor H

    2014-04-01

    Nuclear magnetic resonance (NMR) spectroscopy has been giving a pivotal contribution to the progress of glycomics, mostly by elucidating the structural, dynamical, conformational and intermolecular binding aspects of carbohydrates. Particularly in the field of conformation, NOE resonances, scalar couplings, residual dipolar couplings, and chemical shift anisotropy offsets have been the principal NMR parameters utilized. Molecular dynamics calculations restrained by NMR-data input are usually employed in conjunction to generate glycosidic bond dihedral angles. Glycosaminoglycans (GAGs) are a special class of sulfated polysaccharides extensively studied worldwide. Besides regulating innumerous physiological processes, these glycans are also widely explored in the global market as either clinical or nutraceutical agents. The conformational aspects of GAGs are key regulators to the quality of interactions with the functional proteins involved in biological events. This report discusses the solution conformation of each GAG type analyzed by one or more of the above-mentioned methods.

  13. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2004-09-30

    This report describes work performed during the third and final year of the project, ''Conformance Improvement Using Gels.'' Corefloods revealed throughput dependencies of permeability reduction by polymers and gels that were much more prolonged during oil flow than water flow. This behavior was explained using simple mobility ratio arguments. A model was developed that quantitatively fits the results and predicts ''clean up'' times for oil productivity when production wells are returned to service after application of a polymer or gel treatment. X-ray computed microtomography studies of gels in strongly water-wet Berea sandstone and strongly oil-wet porous polyethylene suggested that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than gel-ripping or gel-displacement mechanisms. In contrast, analysis of data from the University of Kansas suggests that the gel-ripping or displacement mechanisms are more important in more permeable, strongly water-wet sandpacks. These findings help to explain why aqueous gels can reduce permeability to water more than to oil under different conditions. Since cement is the most commonly used material for water shutoff, we considered when gels are preferred over cements. Our analysis and experimental results indicated that cement cannot be expected to completely fill (top to bottom) a vertical fracture of any width, except near the wellbore. For vertical fractures with apertures less than 4 mm, the cement slurry will simply not penetrate very far into the fracture. For vertical fractures with apertures greater than 4 mm, the slurry may penetrate a substantial distance into the bottom part of the fracture. However, except near the wellbore, the upper part of the fracture will remain open due to gravity segregation. We compared various approaches to plugging fractures using gels, including (1) varying polymer content, (2) varying placement (extrusion) rate, (3) using partially formed gels, (4

  14. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2004-03-01

    This technical progress report describes work performed from September 1, 2003, through February 29, 2004, for the project, ''Conformance Improvement Using Gels.'' We examined the properties of several ''partially formed'' gels that were formulated with a combination of high and low molecular weight HPAM polymers. After placement in 4-mm-wide fractures, these gels required about 25 psi/ft for brine to breach the gel (the best performance to date in fractures this wide). After this breach, stabilized residual resistance factors decreased significantly with increased flow rate. Also, residual resistance factors were up to 9 times greater for water than for oil. Nevertheless, permeability reduction factors were substantial for both water and oil flow. Gel with 2.5% chopped fiberglass effectively plugged 4-mm-wide fractures if a 0.5-mm-wide constriction was present. The ability to screen-out at a constriction appears crucial for particulate incorporation to be useful in plugging fractures. In addition to fiberglass, we examined incorporation of polypropylene fibers into gels. Once dispersed in brine or gelant, the polypropylene fibers exhibited the least gravity segregation of any particulate that we have tested to date. In fractures with widths of at least 2 mm, 24-hr-old gels (0.5% high molecular weight HPAM) with 0.5% fiber did not exhibit progressive plugging during placement and showed extrusion pressure gradients similar to those of gels without the fiber. The presence of the fiber roughly doubled the gel's resistance to first breach by brine flow. The breaching pressure gradients were not as large as for gels made with high and low molecular weight polymers (mentioned above). However, their material requirements and costs (i.e., polymer and/or particulate concentrations) were substantially lower than for those gels. A partially formed gel made with 0.5% HPAM did not enter a 0.052-mm-wide fracture when applying a pressure gradient of 65 psi/ft. This result

  15. Exploring the conformational energy landscape of proteins

    SciTech Connect

    Nienhaus, G.U. |; Mueller, J.D.; McMahon, B.H.

    1997-04-01

    Proteins possess a complex energy landscape with a large number of local minima called conformational substates that are arranged in a hierarchical fashion. Here we discuss experiments aimed at the elucidation of the energy landscape in carbonmonoxy myoglobin (MbCO). In the highest tier of the hierarchy, a few taxonomic substates exist. Because of their small number, these substates are accessible to detailed structural investigations. Spectroscopic experiments are discussed that elucidate the role of protonations of amino acid side chains in creating the substates. The lower tiers of the hierarchy contain a large number of statistical substates. Substate interconversions are observed in the entire temperature range from below 1 K up to the denaturation temperature, indicating a wide spectrum of energy barriers that separate the substates.

  16. COCO: a simple tool to enrich the representation of conformational variability in NMR structures.

    PubMed

    Laughton, Charles A; Orozco, Modesto; Vranken, Wim

    2009-04-01

    NMR structures are typically deposited in databases such as the PDB in the form of an ensemble of structures. Generally, each of the models in such an ensemble satisfies the experimental data and is equally valid. No unique solution can be calculated because the experimental NMR data is insufficient, in part because it reflects the conformational variability and dynamical behavior of the molecule in solution. Even for relatively rigid molecules, the limited number of structures that are typically deposited cannot completely encompass the structural diversity allowed by the observed NMR data, but they can be chosen to try and maximize its representation. We describe here the adaptation and application of techniques more commonly used to examine large ensembles from molecular dynamics simulations, to the analysis of NMR ensembles. The approach, which is based on principal component analysis, we call COCO ("Complementary Coordinates"). The COCO approach analyses the distribution of an NMR ensemble in conformational space, and generates a new ensemble that fills "gaps" in the distribution. The method is very rapid, and analysis of a 25-member ensemble and generation of a new 25 member ensemble typically takes 1-2 min on a conventional workstation. Applied to the 545 structures in the RECOORD database, we find that COCO generates new ensembles that are as structurally diverse-both from each other and from the original ensemble-as are the structures within the original ensemble. The COCO approach does not explicitly take into account the NMR restraint data, yet in tests on selected structures from the RECOORD database, the COCO ensembles are frequently good matches to this data, and certainly are structures that can be rapidly refined against the restraints to yield high-quality, novel solutions. COCO should therefore be a useful aid in NMR structure refinement and in other situations where a richer representation of conformational variability is desired-for example in

  17. Increased conformity offers diminishing returns for reducing total knee replacement wear.

    PubMed

    Fregly, Benjamin J; Marquez-Barrientos, Carlos; Banks, Scott A; DesJardins, John D

    2010-02-01

    Wear remains a significant problem limiting the lifespan of total knee replacements (TKRs). Though increased conformity between TKR components has the potential to decrease wear, the optimal amount and planes of conformity have not been investigated. Furthermore, differing conformities in the medial and lateral compartments may provide designers the opportunity to address both wear and kinematic design goals simultaneously. This study used a computational model of a Stanmore knee simulator machine and a previously validated wear model to investigate this issue for simulated gait. TKR geometries with different amounts and planes of conformity on the medial and lateral sides were created and tested in two phases. The first phase utilized a wide range of sagittal and coronal conformity combinations to blanket a physically realistic design space. The second phase performed a focused investigation of the conformity conditions from the first phase to which predicted wear volume was sensitive. For the first phase, sagittal but not coronal conformity was found to have a significant effect on predicted wear volume. For the second phase, increased sagittal conformity was found to decrease predicted wear volume in a nonlinear fashion, with reductions gradually diminishing as conformity increased. These results suggest that TKR geometric design efforts aimed at minimizing wear should focus on sagittal rather than coronal conformity and that at least moderate sagittal conformity is desirable in both compartments.

  18. Conformational analysis for some nonclassical antagonists of histamine H3 receptor

    NASA Astrophysics Data System (ADS)

    Borota, Ana; Mracec, Maria; Rad, Ramona; Ostopovici, Liliana; Mracec, Mircea

    A conformational search in vacuum for a series of 1,3-substituted pyrrolidine derivatives has been performed using the AMBER, AM1, PM3, and MNDO methods. Conformational analysis of the pyrrolidine ligands suggests that these compounds could have many conformers that populate the low-energy minima on the potential energy surface (PES). The conformational space occupied by the ligands is large and, in vacuum, the rotation barriers of different flexible bonds have energies between 0.5 and thousands of kcal/mol. By optimization, most conformers have energy barriers of 0-5 kcal/mol; thus, they could interconvert easily to obtain better interactions in the receptor active site. Optimized conformers having energy barriers of >5 kcal/mol display bad geometries with very large bond lengths and deformed rings. Shapes and heights of rotation barriers obtained through COSMO-AM1 single-point calculations in water are similar to those obtained from single-point calculations in vacuum. However, in water the energy barriers are lower, allowing most conformers to convert in other low-energy conformers. The best conformers in vacuum and in water are different: the gas phase best conformer has a helical shape, while the best conformer in water has an extended shape.

  19. 18 CFR 1307.6 - Accessibility.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... conformance with Sections 3-8 of the Uniform Federal Accessibility Standards (UFAS) (41 CFR Subpart 101-19.6... buildings. Departures from particular technical and scoping requirements of UFAS by the use of other methods... provided. (3) For purposes of this section, section 4.1.6(1)(g) of UFAS shall be interpreted to exempt...

  20. 5 CFR 900.705 - Program accessibility.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of buildings in conformance with sections 3-8 of the Uniform Federal Accessibility Standards (UFAS... respect to those buildings. Departures from particular technical and scoping requirements of UFAS by the... of the building is provided. (2) For purposes of this section, section 4.1.6(1)(g) of UFAS shall...

  1. 18 CFR 1307.6 - Accessibility.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... conformance with Sections 3-8 of the Uniform Federal Accessibility Standards (UFAS) (41 CFR Subpart 101-19.6... buildings. Departures from particular technical and scoping requirements of UFAS by the use of other methods... provided. (3) For purposes of this section, section 4.1.6(1)(g) of UFAS shall be interpreted to exempt...

  2. 5 CFR 900.705 - Program accessibility.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of buildings in conformance with sections 3-8 of the Uniform Federal Accessibility Standards (UFAS... respect to those buildings. Departures from particular technical and scoping requirements of UFAS by the... of the building is provided. (2) For purposes of this section, section 4.1.6(1)(g) of UFAS shall...

  3. 5 CFR 900.705 - Program accessibility.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of buildings in conformance with sections 3-8 of the Uniform Federal Accessibility Standards (UFAS... respect to those buildings. Departures from particular technical and scoping requirements of UFAS by the... of the building is provided. (2) For purposes of this section, section 4.1.6(1)(g) of UFAS shall...

  4. 18 CFR 1307.6 - Accessibility.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... conformance with Sections 3-8 of the Uniform Federal Accessibility Standards (UFAS) (41 CFR Subpart 101-19.6... buildings. Departures from particular technical and scoping requirements of UFAS by the use of other methods... provided. (3) For purposes of this section, section 4.1.6(1)(g) of UFAS shall be interpreted to exempt...

  5. 5 CFR 900.705 - Program accessibility.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of buildings in conformance with sections 3-8 of the Uniform Federal Accessibility Standards (UFAS... respect to those buildings. Departures from particular technical and scoping requirements of UFAS by the... of the building is provided. (2) For purposes of this section, section 4.1.6(1)(g) of UFAS shall...

  6. 5 CFR 900.705 - Program accessibility.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of buildings in conformance with sections 3-8 of the Uniform Federal Accessibility Standards (UFAS... respect to those buildings. Departures from particular technical and scoping requirements of UFAS by the... of the building is provided. (2) For purposes of this section, section 4.1.6(1)(g) of UFAS shall...

  7. 18 CFR 1307.6 - Accessibility.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... conformance with Sections 3-8 of the Uniform Federal Accessibility Standards (UFAS) (41 CFR Subpart 101-19.6... buildings. Departures from particular technical and scoping requirements of UFAS by the use of other methods... provided. (3) For purposes of this section, section 4.1.6(1)(g) of UFAS shall be interpreted to exempt...

  8. 18 CFR 1307.6 - Accessibility.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... conformance with Sections 3-8 of the Uniform Federal Accessibility Standards (UFAS) (41 CFR subpart 101-19.6... buildings. Departures from particular technical and scoping requirements of UFAS by the use of other methods... provided. (3) For purposes of this section, section 4.1.6(1)(g) of UFAS shall be interpreted to exempt...

  9. CONFORMANCE IMPROVEMENT USING GELS

    SciTech Connect

    Randall S. Seright

    2003-09-01

    This report describes work performed during the second year of the project, ''Conformance Improvement Using Gels.'' The project has two objectives. The first objective is to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective is to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil. Pore-level images from X-ray computed microtomography were re-examined for Berea sandstone and porous polyethylene. This analysis suggests that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than a gel-ripping mechanism. This finding helps to explain why aqueous gels can reduce permeability to water more than to oil. We analyzed a Cr(III)-acetate-HPAM gel treatment in a production well in the Arbuckle formation. The availability of accurate pressure data before, during, and after the treatment was critical for the analysis. After the gel treatment, water productivity was fairly constant at about 20% of the pre-treatment value. However, oil productivity was stimulated by a factor of 18 immediately after the treatment. During the six months after the treatment, oil productivity gradually decreased to approach the pre-treatment value. To explain this behavior, we proposed that the fracture area open to oil flow was increased substantially by the gel treatment, followed by a gradual closing of the fractures during subsequent production. For a conventional Cr(III)-acetate-HPAM gel, the delay between gelant preparation and injection into a fracture impacts the placement, leakoff, and permeability reduction behavior. Formulations placed as partially formed gels showed relatively low pressure gradients during placement, and yet substantially reduced the flow capacity of

  10. Influence of rotational energy barriers to the conformational search of protein loops in molecular dynamics and ranking the conformations.

    PubMed

    Tappura, K

    2001-08-15

    An adjustable-barrier dihedral angle potential was added as an extension to a novel, previously presented soft-core potential to study its contribution to the efficacy of the search of the conformational space in molecular dynamics. As opposed to the conventional soft-core potential functions, the leading principle in the design of the new soft-core potential, as well as of its extension, the soft-core and adjustable-barrier dihedral angle (SCADA) potential (referred as the SCADA potential), was to maintain the main equilibrium properties of the original force field. This qualifies the methods for a variety of a priori modeling problems without need for additional restraints typically required with the conventional soft-core potentials. In the present study, the different potential energy functions are applied to the problem of predicting loop conformations in proteins. Comparison of the performance of the soft-core and SCADA potential showed that the main hurdles for the efficient sampling of the conformational space of (loops in) proteins are related to the high-energy barriers caused by the Lennard-Jones and Coulombic energy terms, and not to the rotational barriers, although the conformational search can be further enhanced by lowering the rotational barriers of the dihedral angles. Finally, different evaluation methods were studied and a few promising criteria found to distinguish the near-native loop conformations from the wrong ones.

  11. Expanding Access

    ERIC Educational Resources Information Center

    Roach, Ronald

    2007-01-01

    There is no question that the United States lags behind most industrialized nations in consumer access to broadband Internet service. For many policy makers and activists, this shortfall marks the latest phase in the struggle to overcome the digital divide. To remedy this lack of broadband affordability and availability, one start-up firm--with…

  12. Easy Access

    ERIC Educational Resources Information Center

    Gettelman, Alan

    2009-01-01

    School and university restrooms, locker and shower rooms have specific ADA accessibility requirements that serve the needs of staff, students and campus visitors who are disabled as a result of injury, illness or age. Taking good care of them is good for the reputation of a sensitive community institution, and fosters positive public relations.…

  13. Access Denied

    ERIC Educational Resources Information Center

    Raths, David

    2012-01-01

    As faculty members add online and multimedia elements to their courses, colleges and universities across the country are realizing that there is a lot of work to be done to ensure that disabled students (and employees) have equal access to course material and university websites. Unfortunately, far too few schools consider the task a top priority.…

  14. To conform or not to conform: spontaneous conformity diminishes the sensitivity to monetary outcomes.

    PubMed

    Yu, Rongjun; Sun, Sai

    2013-01-01

    When people have different opinions in a group, they often adjust their own attitudes and behaviors to match the group opinion, known as social conformity. The affiliation account of normative conformity states that people conform to norms in order to 'fit in', whereas the accuracy account of informative conformity posits that the motive to learn from others produces herding. Here, we test another possibility that following the crowd reduces the experienced negative emotion when the group decision turns out to be a bad one. Using event related potential (ERP) combined with a novel group gambling task, we found that participants were more likely to choose the option that was predominately chosen by other players in previous trials, although there was little explicit normative pressure at the decision stage and group choices were not informative. When individuals' choices were different from others, the feedback related negativity (FRN), an ERP component sensitive to losses and errors, was enhanced, suggesting that being independent is aversive. At the outcome stage, the losses minus wins FRN effect was significantly reduced following conformity choices than following independent choices. Analyses of the P300 revealed similar patterns both in the response and outcome period. Our study suggests that social conformity serves as an emotional buffer that protects individuals from experiencing strong negative emotion when the outcomes are bad.

  15. To Conform or Not to Conform: Spontaneous Conformity Diminishes the Sensitivity to Monetary Outcomes

    PubMed Central

    2013-01-01

    When people have different opinions in a group, they often adjust their own attitudes and behaviors to match the group opinion, known as social conformity. The affiliation account of normative conformity states that people conform to norms in order to ‘fit in’, whereas the accuracy account of informative conformity posits that the motive to learn from others produces herding. Here, we test another possibility that following the crowd reduces the experienced negative emotion when the group decision turns out to be a bad one. Using event related potential (ERP) combined with a novel group gambling task, we found that participants were more likely to choose the option that was predominately chosen by other players in previous trials, although there was little explicit normative pressure at the decision stage and group choices were not informative. When individuals' choices were different from others, the feedback related negativity (FRN), an ERP component sensitive to losses and errors, was enhanced, suggesting that being independent is aversive. At the outcome stage, the losses minus wins FRN effect was significantly reduced following conformity choices than following independent choices. Analyses of the P300 revealed similar patterns both in the response and outcome period. Our study suggests that social conformity serves as an emotional buffer that protects individuals from experiencing strong negative emotion when the outcomes are bad. PMID:23691242

  16. Polyproline II conformation is one of many local conformational states and is not an overall conformation of unfolded peptides and proteins

    PubMed Central

    Makowska, Joanna; Rodziewicz-Motowidło, Sylwia; Bagińska, Katarzyna; Vila, Jorge A.; Liwo, Adam; Chmurzyński, Lech; Scheraga, Harold A.

    2006-01-01

    The alanine-based peptide Ac-XX(A)7OO-NH2, referred to as XAO (where X, A, and O denote diaminobutyric acid, alanine, and ornithine, respectively), has recently been proposed to possess a well defined polyproline II (PII) conformation at low temperatures. Based on the results of extensive NMR and CD investigations combined with theoretical calculations, reported here, we present evidence that, on the contrary, this peptide does not have any significant amount of organized PII structure but exists in an ensemble of conformations with a distorted bend in the N- and C-terminal regions. The conformational ensemble was obtained by molecular dynamics/simulated annealing calculations using the amber suite of programs with time-averaged distance and dihedral-angle restraints obtained from rotating-frame nuclear Overhauser effect (ROE) volumes and vicinal coupling constants 3JHNΗα, respectively. The computed ensemble-averaged radius of gyration Rg (7.4 ± 1.0) Å is in excellent agreement with that measured by small-angle x-ray scattering (SAXS) whereas, if the XAO peptide were in the PII conformation, Rg would be 11.6 Å. Depending on the pH, peptide concentration, and temperature, the CD spectra of XAO do or do not possess the maximum with positive ellipticity in the 217-nm region, which is characteristic of the PII structure, reflecting a shifting conformational equilibrium rather than an all-or-none transition. The “PII conformation” should, therefore, be considered as one of the accessible conformational states of individual amino acid residues in peptides and proteins rather than as a structure of most of the chain in the early stage of folding. PMID:16446433

  17. A fragment based step-by-step strategy for determining the most stable conformers of biomolecules

    NASA Astrophysics Data System (ADS)

    Li, Hongbao; Lin, Zijing; Luo, Yi

    2014-08-01

    For biomolecules of increased size and flexibility, more efficient and reliable strategies are always needed to determine their stable low-energy conformers. Here, we propose a fragment based step-by-step strategy to search for the full conformational space of biomolecules. In this strategy, the molecule is divided into several fragments and each of them is systematically optimized in a step-by-step fashion. It can significantly reduce the computational cost without losing any accuracy as demonstrated by the conformer search of several representative di-/tri-/tetra-peptides. Such an approach will be very useful for finding the stable conformers of large biomolecules.

  18. Holographic instant conformal symmetry breaking by colliding conical defects

    NASA Astrophysics Data System (ADS)

    Ageev, D. S.; Aref'eva, I. Ya.

    2016-12-01

    We study instant conformal symmetry breaking as a holographic effect of ultrarelativistic particles moving in the AdS3 space-time. We give a qualitative picture of this effect based on calculating the two-point correlation functions and the entanglement entropy of the corresponding boundary theory. We show that in the geodesic approximation, because of gravitational lensing of the geodesics, the ultrarelativistic massless defect produces a zone structure for correlators with broken conformal invariance. At the same time, the holographic entanglement entropy also exhibits a transition to nonconformal behavior. Two colliding massless defects produce a more diverse zone structure for correlators and the entanglement entropy.

  19. Conformal invariance, dynamical dark energy and the CMB

    SciTech Connect

    Mottola, Emil

    2010-01-01

    Einstein's General Relativity receives quantum corrections relevant at cosmological distance scales. These effects arise from conformal scalar degrees of freedom in the extended Effective Field Theory (EFT) of gravity required by the trace anomaly of the quantum stress tensor in curved space. Scalar degrees of freedom in cosmology arise naturally from the effective action of the trace anomaly in the Standard Model, without the ad hoc introduction of an inflaton field. In the EFT including the trace anomaly terms, {Lambda}{sub eff} becomes dynamical and potentially dependent upon both space and time. The fluctuations of these anomaly scalars may also influence the spectrum and statistics of the Cosmic Microwave Background (CMB). Under the hypothesis that scale invariance should be promoted to full conformal invariance, an hypothesis supported by the embedding of the conformal group of three dimensional flat sections in de Sitter space, the form of the CMB bi-spectrum can be fixed, and the tri-spectrum constrained. The angular spectra predicted by conformal invariance differ from those suggested by simple models of inflation.

  20. Prediction of conformationally dependent atomic multipole moments in carbohydrates.

    PubMed

    Cardamone, Salvatore; Popelier, Paul L A

    2015-12-15

    The conformational flexibility of carbohydrates is challenging within the field of computational chemistry. This flexibility causes the electron density to change, which leads to fluctuating atomic multipole moments. Quantum Chemical Topology (QCT) allows for the partitioning of an "atom in a molecule," thus localizing electron density to finite atomic domains, which permits the unambiguous evaluation of atomic multipole moments. By selecting an ensemble of physically realistic conformers of a chemical system, one evaluates the various multipole moments at defined points in configuration space. The subsequent implementation of the machine learning method kriging delivers the evaluation of an analytical function, which smoothly interpolates between these points. This allows for the prediction of atomic multipole moments at new points in conformational space, not trained for but within prediction range. In this work, we demonstrate that the carbohydrates erythrose and threose are amenable to the above methodology. We investigate how kriging models respond when the training ensemble incorporating multiple energy minima and their environment in conformational space. Additionally, we evaluate the gains in predictive capacity of our models as the size of the training ensemble increases. We believe this approach to be entirely novel within the field of carbohydrates. For a modest training set size of 600, more than 90% of the external test configurations have an error in the total (predicted) electrostatic energy (relative to ab initio) of maximum 1 kJ mol(-1) for open chains and just over 90% an error of maximum 4 kJ mol(-1) for rings.

  1. Treatment planning for conformal proton radiation therapy.

    PubMed

    Bussière, Mark R; Adams, Judith A

    2003-10-01

    Clinical results from various trials have demonstrated the viability of protons in radiation therapy and radiosurgery. This has motivated a few large medical centers to design and build expensive hospital based proton facilities based proton facilities (current cost estimates for a proton facility is around 100 million US dollars). Until this development proton therapy was done using retrofitted equipment originally designed for nuclear experiments. There are presently only three active proton therapy centers in the United States, 22 worldwide. However, more centers are under construction and being proposed in the US and abroad. The important difference between proton and x-ray therapy is in the dose distribution. X-rays deposit most of their dose at shallow depths of a few centimeters with a gradual decay with depth in the patient. Protons deliver most of their dose in the Bragg peak, which can be delivered at most clinically required depths followed by a sharp fall-off. This sharp falloff makes protons sensitive to variations in treatment depths within patients. Treatment planning incorporates all the knowledge of protons into a process, which allows patients to be treated accurately and reliably. This process includes patient immobilization, imaging, targeting, and modeling of planned dose distributions. Although the principles are similar to x-ray therapy some significant differences exist in the planning process, which described in this paper. Target dose conformality has recently taken on much momentum with the advent of intensity modulated radiation therapy (IMRT) with photon beams. Proton treatments provide a viable alternative to IMRT because they are inherently conformal avoiding normal tissue while irradiating the intended targets. Proton therapy will soon bring conformality to a new high with the development of intensity modulated proton therapy (IMPT). Future challenges include keeping the cost down, increasing access to conventional proton therapy as

  2. Annual Report Electrochemical Machining of Access Holes

    SciTech Connect

    Cooper, J F; Evans, M; Whipple, R

    2006-01-04

    We report the advances made in electrochemical machining of access holes through sheet metal during FY2005. The cutting tool underwent a major engineering re-design to accommodate an oblong cut with parallel sides (1.5'' spacing) on a surface of arbitrary curvature. The solid cathode was replaced by an array of separately movable steel pins, allowing the tool to conform to the surface shape of the work piece prior to beginning cutting. Preliminary cuts through a hardened steel drum (0.04 inch thickness) were successfully completed at a low current (50A) but the current efficiency of the cutting process was poor (<30%). Efficiency was improved to 75% and the cutting time reduced to 8 minutes in heated electrolyte at 100 A and 4.5 V. This work led to improvements in process simplicity and ease of operation: (1) continuous movement of the cathode towards the work piece was eliminated in favor of a fixed cathode; (2) the surfaces of the cutting pins do not require insulation; (3) a spider support for the tool provides for rapid positioning of the cutting tool; (4) negative electrolyte pressure minimized leakage into the drum following breakthrough. We found no reactivity of various HE's with alternative candidate ECM electrolytes.

  3. 40 CFR 93.154 - Conformity analysis.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Conformity analysis. 93.154 Section 93...) DETERMINING CONFORMITY OF FEDERAL ACTIONS TO STATE OR FEDERAL IMPLEMENTATION PLANS Determining Conformity of General Federal Actions to State or Federal Implementation Plans § 93.154 Conformity analysis. Any...

  4. History of Space Policy

    DTIC Science & Technology

    2012-03-22

    2012), 1. 2 Winston Churchill, http://www.brainyquote.com/quotes/keywords/history.html (accessed January 8, 2012). 3 Deborah Cadbury , Space Race... Cadbury , Space Race, The Epic Battle Between America and the Soviet Union for Dominion of Space (New York: Harper Collins, 2006), 4. 22 7 Ibid., 5

  5. Proposed Bioactive Conformations of Opiorphin, an Endogenous Dual APN/NEP Inhibitor

    PubMed Central

    2011-01-01

    The conformational profiles for the endogenous peptide Opiorphin and a set of seven analogues exhibiting different inhibitory activities toward human aminopeptidase N (hAPN) and human neprilysin (hNEP) were independently computed to deduce a bioactive conformation that Opiorphin may adopt when binding these two enzymes. The conformational space was thoroughly sampled using an iterative simulated annealing protocol, and a library of low-energy conformers was generated for each peptide. Bioactive Opiorphin conformations fitting our experimental structure–activity relationship data were identified for hAPN and hNEP using computational pairwise comparisons between each of the unique low-energy conformations of Opiorphin and its analogues. The obtained results provide a structural explanation for the dual hAPN and hNEP inhibitory activity of Opiorphin and show that the inborn flexibility of Opiorphin is essential for its analgesic activity. PMID:24900367

  6. Proposed Bioactive Conformations of Opiorphin, an Endogenous Dual APN/NEP Inhibitor.

    PubMed

    Pinto, Marta; Rougeot, Catherine; Gracia, Luis; Rosa, Mònica; García, Andrés; Arsequell, Gemma; Valencia, Gregorio; Centeno, Nuria B

    2012-01-12

    The conformational profiles for the endogenous peptide Opiorphin and a set of seven analogues exhibiting different inhibitory activities toward human aminopeptidase N (hAPN) and human neprilysin (hNEP) were independently computed to deduce a bioactive conformation that Opiorphin may adopt when binding these two enzymes. The conformational space was thoroughly sampled using an iterative simulated annealing protocol, and a library of low-energy conformers was generated for each peptide. Bioactive Opiorphin conformations fitting our experimental structure-activity relationship data were identified for hAPN and hNEP using computational pairwise comparisons between each of the unique low-energy conformations of Opiorphin and its analogues. The obtained results provide a structural explanation for the dual hAPN and hNEP inhibitory activity of Opiorphin and show that the inborn flexibility of Opiorphin is essential for its analgesic activity.

  7. Protein conformational plasticity and complex ligand-binding kinetics explored by atomistic simulations and Markov models

    PubMed Central

    Plattner, Nuria; Noé, Frank

    2015-01-01

    Understanding the structural mechanisms of protein–ligand binding and their dependence on protein sequence and conformation is of fundamental importance for biomedical research. Here we investigate the interplay of conformational change and ligand-binding kinetics for the serine protease Trypsin and its competitive inhibitor Benzamidine with an extensive set of 150 μs molecular dynamics simulation data, analysed using a Markov state model. Seven metastable conformations with different binding pocket structures are found that interconvert at timescales of tens of microseconds. These conformations differ in their substrate-binding affinities and binding/dissociation rates. For each metastable state, corresponding solved structures of Trypsin mutants or similar serine proteases are contained in the protein data bank. Thus, our wild-type simulations explore a space of conformations that can be individually stabilized by adding ligands or making suitable changes in protein sequence. These findings provide direct evidence of conformational plasticity in receptors. PMID:26134632

  8. Toward Understanding the Conformal Gravity

    NASA Astrophysics Data System (ADS)

    Berezin, V. A.; Dokuchaev, V. I.; Eroshenko, Yu. N.

    2017-03-01

    We constructed the conformally invariant model for scalar particle creation induced by strong gravitational fields. Starting from the usual hydrodynamic description of the particle motion written in the Eulerian coordinates, we substituted the particle number conservation law (which enters the formalism) by the particle creation law, proportional to the square of the Weyl tensor, following the famous result by Ya. B. Zel'dovich and A. A. Starobinsky. Then, demanding the conformal invariance of the whole dynamical system, we have got both the Weyl-conformal gravity and the Einstein-Hilbert dilaton gravity action integral. Thus, we obtained something like the induced gravity suggested first by A. D. Sakharov. It is shown that the resulting system is self-consistent.

  9. Partial masslessness and conformal gravity

    NASA Astrophysics Data System (ADS)

    Deser, S.; Joung, E.; Waldron, A.

    2013-05-01

    We use conformal, but ghostful, Weyl gravity to study its ghost-free, second derivative, partially massless (PM) spin-2 component in the presence of Einstein gravity with positive cosmological constant. Specifically, we consider both gravitational- and self-interactions of PM via the fully nonlinear factorization of conformal gravity’s Bach tensor into Einstein times Schouten operators. We find that extending PM beyond linear order suffers from familiar higher spin consistency obstructions: it propagates only in Einstein backgrounds, and the conformal gravity route generates only the usual safe, Noether, cubic order vertices. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Higher spin theories and holography’.

  10. Conformal deposition of LPCVD TEOS

    NASA Astrophysics Data System (ADS)

    McCann, Paul; Somasundram, Kumar; Byrne, Stephen; Nevin, Andrew

    2001-09-01

    The step coverage of dielectrics is important for the microelectronics industry and critical to Micro-machined products and High Voltage MEMS drivers. The techniques used to fabricate MEMS structures require void free refill processes and even film deposition along deep trenches to protect against etch chemistries. High voltage drivers used to actuate MEMS devices benefit from dielectric isolation, which reduces the need for large tub formation between devices. It also enables 'system on chip' solutions for MEMs devices and protection against voltage spikes. This paper presents a process developed at Analog Devices Belfast that enables an LPCVD TEOS furnace to perform a highly conformal trench refill without equipment modification. The conformality is over 95% for 20 micrometer deep trenches and maintains a conformality greater than 85% in 50 micrometer deep trenches. This compares with 75% conformality which is considered excellent for 20 micrometer trench refills obtained using previous LPCVD TEOS processing. The process is shown to have benefits in conformality, breakdown voltage, and stress over standard trench fill processes including Ozone TEOS. The densification of the TEOS film has been optimized for electrical parameters using CV and IV techniques, while XPS, FTIR and spectroscopic ellipsometry are used for physical characterization. Stress is a very important parameter for micro-machining and the conformal TEOS has a film stress which is tensile 30 - 40 MPa as deposited and compressive 100 MPa after densification. The breakdown voltage has been measured at 8.5 MV/cm compared to 7.5 - 9 MV/cm for a typical densified TEOS film and the refractive index is 1.456 compared to 1.465 for a thermal oxide. Analog Devices Belfast is part of the Micro-machined Products division and provides SOI and customized SOI for the MEMs and IC market.

  11. Conformers, infrared spectrum, UV-induced photochemistry, and near-IR-induced generation of two rare conformers of matrix-isolated phenylglycine

    NASA Astrophysics Data System (ADS)

    Borba, Ana; Gómez-Zavaglia, Andrea; Fausto, Rui

    2014-10-01

    The conformational space of α-phenylglycine (PG) have been investigated theoretically at both the DFT/B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) levels of approximation. Seventeen different minima were found on the investigated potential energy surfaces, which are characterized by different dominant intramolecular interactions: type I conformers are stabilized by hydrogen bonds of the type N-H...O=C, type II by a strong O-H...N hydrogen bond, type III by weak N-H...O-H hydrogen bonds, and type IV by a C=O...H-C contact. The calculations indicate also that entropic effects are relevant in determining the equilibrium populations of the conformers of PG in the gas phase, in particular in the case of conformers of type II, where the strong intramolecular O-H...N hydrogen bond considerably diminishes entropy by reducing the conformational mobility of the molecule. In consonance with the relative energies of the conformers and barriers for conformational interconversion, only 3 conformers of PG were observed for the compound isolated in cryogenic Ar, Xe, and N2 matrices: the conformational ground state (ICa), and forms ICc and IITa. All other significantly populated conformers existing in the gas phase prior to deposition convert either to conformer ICa or to conformer ICc during matrix deposition. The experimental observation of ICc had never been achieved hitherto. Narrowband near-IR irradiation of the first overtone of νOH vibrational mode of ICa and ICc in nitrogen matrices (at 6910 and 6930 cm-1, respectively) led to selective generation of two additional conformers of high-energy, ITc and ITa, respectively, which were also observed experimentally for the first time. In addition, these experiments also provided the key information for the detailed vibrational characterization of the 3 conformers initially present in the matrices. On the other hand, UV irradiation (λ = 255 nm) of PG isolated in a xenon matrix revealed that PG undergoes facile photofragmentation

  12. Conformers, infrared spectrum, UV-induced photochemistry, and near-IR-induced generation of two rare conformers of matrix-isolated phenylglycine

    SciTech Connect

    Borba, Ana Fausto, Rui; Gómez-Zavaglia, Andrea

    2014-10-21

    The conformational space of α-phenylglycine (PG) have been investigated theoretically at both the DFT/B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) levels of approximation. Seventeen different minima were found on the investigated potential energy surfaces, which are characterized by different dominant intramolecular interactions: type I conformers are stabilized by hydrogen bonds of the type N–H···O=C, type II by a strong O–H···N hydrogen bond, type III by weak N–H···O–H hydrogen bonds, and type IV by a C=O···H–C contact. The calculations indicate also that entropic effects are relevant in determining the equilibrium populations of the conformers of PG in the gas phase, in particular in the case of conformers of type II, where the strong intramolecular O–H···N hydrogen bond considerably diminishes entropy by reducing the conformational mobility of the molecule. In consonance with the relative energies of the conformers and barriers for conformational interconversion, only 3 conformers of PG were observed for the compound isolated in cryogenic Ar, Xe, and N{sub 2} matrices: the conformational ground state (ICa), and forms ICc and IITa. All other significantly populated conformers existing in the gas phase prior to deposition convert either to conformer ICa or to conformer ICc during matrix deposition. The experimental observation of ICc had never been achieved hitherto. Narrowband near-IR irradiation of the first overtone of νOH vibrational mode of ICa and ICc in nitrogen matrices (at 6910 and 6930 cm{sup −1}, respectively) led to selective generation of two additional conformers of high-energy, ITc and ITa, respectively, which were also observed experimentally for the first time. In addition, these experiments also provided the key information for the detailed vibrational characterization of the 3 conformers initially present in the matrices. On the other hand, UV irradiation (λ = 255 nm) of PG isolated in a xenon matrix revealed that

  13. Development of a conformational search strategy for flexible ligands: A study of the potent μ-selective opioid analgesic fentanyl

    NASA Astrophysics Data System (ADS)

    Cometta-Morini, Chiara; Loew, Gilda H.

    1991-08-01

    An extensive conformational search of the potent opioid analgesic, fentanyl, was performed using the semiempirical quantum mechanical method AM1 and the CHARMm potential energy function. A combination of two procedures was used to search the conformational space for fentanyl, which included nested dihedral scans, geometry optimization and molecular dynamics simulation at different temperatures. In addition, the effect of a continuum solvent environment was taken into account by use of appropriate values for the dielectric constant in the CHARMm computations. The results of the conformational search allowed the determination of the probable conformation of fentanyl in polar and nonpolar solvents and of three candidate conformers for its bioactive form.

  14. Correspondence between Asymptotically Flat Spacetimes and Nonrelativistic Conformal Field Theories

    SciTech Connect

    Bagchi, Arjun

    2010-10-22

    We find a surprising connection between asymptotically flat spacetimes and nonrelativistic conformal systems in one lower dimension. The Bondi-Metzner-Sachs (BMS) group is the group of asymptotic isometries of flat Minkowski space at null infinity. This is known to be infinite dimensional in three and four dimensions. We show that the BMS algebra in 3 dimensions is the same as the 2D Galilean conformal algebra (GCA) which is of relevance to nonrelativistic conformal symmetries. We further justify our proposal by looking at a Penrose limit on a radially infalling null ray inspired by nonrelativistic scaling and obtain a flat metric. The BMS{sub 4} algebra is also discussed and found to be the same as another class of GCA, called semi-GCA, in three dimensions. We propose a general BMS-GCA correspondence. Some consequences are discussed.

  15. Plan-graph Based Heuristics for Conformant Probabilistic Planning

    NASA Technical Reports Server (NTRS)

    Ramakrishnan, Salesh; Pollack, Martha E.; Smith, David E.

    2004-01-01

    In this paper, we introduce plan-graph based heuristics to solve a variation of the conformant probabilistic planning (CPP) problem. In many real-world problems, it is the case that the sensors are unreliable or take too many resources to provide knowledge about the environment. These domains are better modeled as conformant planning problems. POMDP based techniques are currently the most successful approach for solving CPP but have the limitation of state- space explosion. Recent advances in deterministic and conformant planning have shown that plan-graphs can be used to enhance the performance significantly. We show that this enhancement can also be translated to CPP. We describe our process for developing the plan-graph heuristics and estimating the probability of a partial plan. We compare the performance of our planner PVHPOP when used with different heuristics. We also perform a comparison with a POMDP solver to show over a order of magnitude improvement in performance.

  16. Conformal Doping of FINFETs: a Fabrication and Metrology Challenge

    SciTech Connect

    Vandervorst, W.; Mody, J.; Zschaetzsch, G.; Koelling, S.; Everaert, J. L.; Rosseel, E.; Jurczak, M.; Hoffman, T.; Eyben, P.; Gilbert, M.; Poon, T.; Del Agua Borniquel, J.; Foad, M.; Duffy, R.; Pawlak, B. J.

    2008-11-03

    Whereas the introduction of 3D-dimensional devices such as FINFETs may be a solution for next generation technologies, they do represent significant challenges with respect to the doping strategies and the junction characterization. Aiming at a conformal doping, classical beam implants fail due to the differences in impact angle, ion incorporation efficiency and the effect of wafer rotation. Moreover shadowing represents an additional limitation for larger tilt angles when considering closely spaced FINs. Plasma immersion doping is an alternative approach which holds the promise of conformality but is also quite challenging and relies on secondary processes such as resputtering, deposition and in diffusion etc. Its implementation is compromised by concurrent artifacts, sputter erosion being the most important one. In support of these developments the measurement of the 3D-dopant distribution and the identification of conformality is essential requiring adequate metrology such as Scanning Spreading Resistance Microscopy, SIMS through FINs, resistors and the Tomographic Atomprobe.

  17. Dynamic Methods for Investigating the Conformational Changes of Biological Macromolecules

    NASA Astrophysics Data System (ADS)

    Vidolova-Angelova, E.; Peshev, Z.; Shaquiri, Z.; Angelov, D.

    2010-01-01

    Fast conformational changes of biological macromolecules such as RNA folding and DNA—protein interactions play a crucial role in their biological functions. Conformational changes are supposed to take place in the sub milliseconds to few seconds time range. The development of appropriate dynamic methods possessing both high space (one nucleotide) and time resolution is of important interest. Here, we present two different approaches we developed for studying nucleic acid conformational changes such as salt-induced tRNA folding and interaction of the transcription factor NF-κB with its recognition DNA sequence. Importantly, only a single laser pulse is sufficient for the accurate measuring the whole decay curve. This peculiarity can be used in dynamical experiments.

  18. Hemodialysis access - self care

    MedlinePlus

    Kidney failure - chronic-hemodialysis access; Renal failure - chronic-hemodialysis access; Chronic renal insufficiency - hemodialysis access; Chronic kidney failure - hemodialysis access; Chronic renal failure - hemodialysis access; dialysis - hemodialysis ...

  19. Algebraic orbifold conformal field theories

    PubMed Central

    Xu, Feng

    2000-01-01

    The unitary rational orbifold conformal field theories in the algebraic quantum field theory and subfactor theory framework are formulated. Under general conditions, it is shown that the orbifold of a given unitary rational conformal field theory generates a unitary modular category. Many new unitary modular categories are obtained. It is also shown that the irreducible representations of orbifolds of rank one lattice vertex operator algebras give rise to unitary modular categories and determine the corresponding modular matrices, which has been conjectured for some time. PMID:11106383

  20. SUSY Unparticle and Conformal Sequestering

    SciTech Connect

    Nakayama, Yu; Nakayama, Yu

    2007-07-17

    We investigate unparticle physics with supersymmetry (SUSY). The SUSY breaking effects due to the gravity mediation induce soft masses for the SUSY unparticles and hence break the conformal invariance. The unparticle physics observable in near future experiments is only consistent if the SUSY breakingeffects from the hidden sector to the standard model sector are dominated by the gauge mediation, or if the SUSY breaking effects to the unparticle sector are sufficiently sequestered. We argue that the natural realization of the latter possibility is the conformal sequestering scenario.

  1. Nonlocal gravity: Conformally flat spacetimes

    NASA Astrophysics Data System (ADS)

    Bini, Donato; Mashhoon, Bahram

    2016-04-01

    The field equations of the recent nonlocal generalization of Einstein’s theory of gravitation are presented in a form that is reminiscent of general relativity. The implications of the nonlocal field equations are studied in the case of conformally flat spacetimes. Even in this simple case, the field equations are intractable. Therefore, to gain insight into the nature of these equations, we investigate the structure of nonlocal gravity (NLG) in 2D spacetimes. While any smooth 2D spacetime is conformally flat and satisfies Einstein’s field equations, only a subset containing either a Killing vector or a homothetic Killing vector can satisfy the field equations of NLG.

  2. Social influence: compliance and conformity.

    PubMed

    Cialdini, Robert B; Goldstein, Noah J

    2004-01-01

    This review covers recent developments in the social influence literature, focusing primarily on compliance and conformity research published between 1997 and 2002. The principles and processes underlying a target's susceptibility to outside influences are considered in light of three goals fundamental to rewarding human functioning. Specifically, targets are motivated to form accurate perceptions of reality and react accordingly, to develop and preserve meaningful social relationships, and to maintain a favorable self-concept. Consistent with the current movement in compliance and conformity research, this review emphasizes the ways in which these goals interact with external forces to engender social influence processes that are subtle, indirect, and outside of awareness.

  3. Epigenetic Dominance of Prion Conformers

    PubMed Central

    Saijo, Eri; Kang, Hae-Eun; Bian, Jifeng; Bowling, Kristi G.; Browning, Shawn; Kim, Sehun; Hunter, Nora; Telling, Glenn C.

    2013-01-01

    Although they share certain biological properties with nucleic acid based infectious agents, prions, the causative agents of invariably fatal, transmissible neurodegenerative disorders such as bovine spongiform encephalopathy, sheep scrapie, and human Creutzfeldt Jakob disease, propagate by conformational templating of host encoded proteins. Once thought to be unique to these diseases, this mechanism is now recognized as a ubiquitous means of information transfer in biological systems, including other protein misfolding disorders such as those causing Alzheimer's and Parkinson's diseases. To address the poorly understood mechanism by which host prion protein (PrP) primary structures interact with distinct prion conformations to influence pathogenesis, we produced transgenic (Tg) mice expressing different sheep scrapie susceptibility alleles, varying only at a single amino acid at PrP residue 136. Tg mice expressing ovine PrP with alanine (A) at (OvPrP-A136) infected with SSBP/1 scrapie prions propagated a relatively stable (S) prion conformation, which accumulated as punctate aggregates in the brain, and produced prolonged incubation times. In contrast, Tg mice expressing OvPrP with valine (V) at 136 (OvPrP-V136) infected with the same prions developed disease rapidly, and the converted prion was comprised of an unstable (U), diffusely distributed conformer. Infected Tg mice co-expressing both alleles manifested properties consistent with the U conformer, suggesting a dominant effect resulting from exclusive conversion of OvPrP-V136 but not OvPrP-A136. Surprisingly, however, studies with monoclonal antibody (mAb) PRC5, which discriminates OvPrP-A136 from OvPrP-V136, revealed substantial conversion of OvPrP-A136. Moreover, the resulting OvPrP-A136 prion acquired the characteristics of the U conformer. These results, substantiated by in vitro analyses, indicated that co-expression of OvPrP-V136 altered the conversion potential of OvPrP-A136 from the S to the

  4. Scale invariance, conformality, and generalized free fields

    SciTech Connect

    Dymarsky, Anatoly; Farnsworth, Kara; Komargodski, Zohar; Luty, Markus A.; Prilepina, Valentina

    2016-02-16

    This paper addresses the question of whether there are 4D Lorentz invariant unitary quantum fi eld theories with scale invariance but not conformal invariance. We present an important loophole in the arguments of Luty-Polchinski-Rattazzi and Dymarsky-Komargodski-Schwimmer-Theisen that is the trace of the energy-momentum tensor T could be a generalized free field. In this paper we rule out this possibility. The key ingredient is the observation that a unitary theory with scale but not conformal invariance necessarily has a non-vanishing anomaly for global scale transformations. We show that this anomaly cannot be reproduced if T is a generalized free field unless the theory also contains a dimension-2 scalar operator. In the special case where such an operator is present it can be used to redefine ("improve") the energy-momentum tensor, and we show that there is at least one energy-momentum tensor that is not a generalized free field. In addition, we emphasize that, in general, large momentum limits of correlation functions cannot be understood from the leading terms of the coordinate space OPE. This invalidates a recent argument by Farnsworth-Luty-Prilepina (FLP). Finally, despite the invalidity of the general argument of FLP, some of the techniques turn out to be useful in the present context.

  5. Scale invariance, conformality, and generalized free fields

    DOE PAGES

    Dymarsky, Anatoly; Farnsworth, Kara; Komargodski, Zohar; ...

    2016-02-16

    This paper addresses the question of whether there are 4D Lorentz invariant unitary quantum fi eld theories with scale invariance but not conformal invariance. We present an important loophole in the arguments of Luty-Polchinski-Rattazzi and Dymarsky-Komargodski-Schwimmer-Theisen that is the trace of the energy-momentum tensor T could be a generalized free field. In this paper we rule out this possibility. The key ingredient is the observation that a unitary theory with scale but not conformal invariance necessarily has a non-vanishing anomaly for global scale transformations. We show that this anomaly cannot be reproduced if T is a generalized free field unlessmore » the theory also contains a dimension-2 scalar operator. In the special case where such an operator is present it can be used to redefine ("improve") the energy-momentum tensor, and we show that there is at least one energy-momentum tensor that is not a generalized free field. In addition, we emphasize that, in general, large momentum limits of correlation functions cannot be understood from the leading terms of the coordinate space OPE. This invalidates a recent argument by Farnsworth-Luty-Prilepina (FLP). Finally, despite the invalidity of the general argument of FLP, some of the techniques turn out to be useful in the present context.« less

  6. Conformal coating value/risk assessment for Sandia satellite programs.

    SciTech Connect

    Russick, Edward Mark; Thayer, Gayle Echo

    2008-03-01

    Conformal coatings are used in space applications on printed circuit board (PCB) assemblies primarily as a protective barrier against environmental contaminants. Such coatings have been used at Sandia for decades in satellite applications including the GPS satellite program. Recently, the value of conformal coating has been questioned because it is time consuming (requiring a 5-6 week schedule allowance) and delays due to difficulty of repairs and rework performed afterward are troublesome. In an effort to find opportunities where assembly time can be reduced, a review of the literature as well as discussions with satellite engineers both within and external to Sandia regarding the value of conformal coating was performed. Several sources on the value of conformal coating, the functions it performs, and on whether coatings are necessary and should be used at all were found, though nearly all were based on anecdotal information. The first section of this report, titled 'Conformal Coating for Space Applications', summarizes the results of an initial risk-value assessment of the conformal coating process for Sandia satellite programs based on information gathered. In the process of collecting information to perform the assessment, it was necessary to obtain a comprehensive understanding of the entire satellite box assembly process. A production time-line was constructed and is presented in the second section of this report, titled 'Satellite Box Assembly', specifically to identify potential sources of time delays, manufacturing issues, and component failures related to the conformal coating process in relation to the box assembly. The time-line also allows for identification of production issues that were anecdotally attributed to the conformal coating but actually were associated with other production steps in the box assembly process. It was constructed largely in consultation with GPS program engineers with empirical knowledge of times required to complete the

  7. The Space Shuttle

    NASA Technical Reports Server (NTRS)

    Moffitt, William L.

    2003-01-01

    As missions have become increasingly more challenging over the years, the most adaptable and capable element of space shuttle operations has proven time and again to be human beings. Human space flight provides unique aspects of observation. interaction and intervention that can reduce risk and improve mission success. No other launch vehicle - in development or in operation today - can match the space shuttle's human space flight capabilities. Preserving U.S. leadership in human space flight requires a strategy to meet those challenges. The ongoing development of next generation vehicles, along with upgrades to the space shuttle, is the most effective means for assuring our access to space.

  8. Electroweak phase transition in nearly conformal technicolor

    SciTech Connect

    Cline, James M.; Jaervinen, Matti; Sannino, Francesco

    2008-10-01

    We examine the temperature-dependent electroweak phase transition in extensions of the standard model in which the electroweak symmetry is spontaneously broken via strongly coupled, nearly conformal dynamics. In particular, we focus on the low energy effective theory used to describe minimal walking technicolor at the phase transition. Using the one-loop effective potential with ring improvement, we identify significant regions of parameter space which yield a sufficiently strong first-order transition for electroweak baryogenesis. The composite particle spectrum corresponding to these regions can be produced and studied at the Large Hadron Collider experiment. We note the possible emergence of a second phase transition at lower temperatures. This occurs when the underlying technicolor theory possesses a nontrivial center symmetry.

  9. Conformal killing tensors and covariant Hamiltonian dynamics

    SciTech Connect

    Cariglia, M.; Gibbons, G. W.; Holten, J.-W. van; Horvathy, P. A.; Zhang, P.-M.

    2014-12-15

    A covariant algorithm for deriving the conserved quantities for natural Hamiltonian systems is combined with the non-relativistic framework of Eisenhart, and of Duval, in which the classical trajectories arise as geodesics in a higher dimensional space-time, realized by Brinkmann manifolds. Conserved quantities which are polynomial in the momenta can be built using time-dependent conformal Killing tensors with flux. The latter are associated with terms proportional to the Hamiltonian in the lower dimensional theory and with spectrum generating algebras for higher dimensional quantities of order 1 and 2 in the momenta. Illustrations of the general theory include the Runge-Lenz vector for planetary motion with a time-dependent gravitational constant G(t), motion in a time-dependent electromagnetic field of a certain form, quantum dots, the Hénon-Heiles and Holt systems, respectively, providing us with Killing tensors of rank that ranges from one to six.

  10. Facilitated diffusion framework for transcription factor search with conformational changes

    NASA Astrophysics Data System (ADS)

    Cartailler, Jérôme; Reingruber, Jürgen

    2015-07-01

    Cellular responses often require the fast activation or repression of specific genes, which depends on transcription factors (TFs) that have to quickly find the promoters of these genes within a large genome. TFs search for their DNA promoter target by alternating between bulk diffusion and sliding along the DNA, a mechanism known as facilitated diffusion. We study a facilitated diffusion framework with switching between three search modes: a bulk mode and two sliding modes triggered by conformational changes between two protein conformations. In one conformation (search mode) the TF interacts unspecifically with the DNA backbone resulting in fast sliding. In the other conformation (recognition mode) it interacts specifically and strongly with DNA base pairs leading to slow displacement. From the bulk, a TF associates with the DNA at a random position that is correlated with the previous dissociation point, which implicitly is a function of the DNA structure. The target affinity depends on the conformation. We derive exact expressions for the mean first passage time (MFPT) to bind to the promoter and the conditional probability to bind before detaching when arriving at the promoter site. We systematically explore the parameter space and compare various search scenarios. We compare our results with experimental data for the dimeric Lac repressor search in E. coli bacteria. We find that a coiled DNA conformation is absolutely necessary for a fast MFPT. With frequent spontaneous conformational changes, a fast search time is achieved even when a TF becomes immobilized in the recognition state due to the specific bindings. We find a MFPT compatible with experimental data in presence of a specific TF-DNA interaction energy that has a Gaussian distribution with a large variance.

  11. Keyless Access

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2009-01-01

    A fundamental truth of building security is that one misplaced key constitutes a crack in the armor that protects a space from unwelcome intruders. Imagine the headaches for administrators and security officials at a large university, where thousands of keys that are distributed to students and staff never find their way back to school officials.…

  12. Molecular mechanics conformational analysis of tylosin

    NASA Astrophysics Data System (ADS)

    Ivanov, Petko M.

    1998-01-01

    The conformations of the 16-membered macrolide antibiotic tylosin were studied with molecular mechanics (AMBER∗ force field) including modelling of the effect of the solvent on the conformational preferences (GB/SA). A Monte Carlo conformational search procedure was used for finding the most probable low-energy conformations. The present study provides complementary data to recently reported analysis of the conformations of tylosin based on NMR techniques. A search for the low-energy conformations of protynolide, a 16-membered lactone containing the same aglycone as tylosin, was also carried out, and the results were compared with the observed conformation in the crystal as well as with the most probable conformations of the macrocyclic ring of tylosin. The dependence of the results on force field was also studied by utilizing the MM3 force field. Some particular conformations were computed with the semiempirical molecular orbital methods AM1 and PM3.

  13. Correct Representation of Conformational Equilibria.

    ERIC Educational Resources Information Center

    Fulop, F.; And Others

    1983-01-01

    In representing conformational equilibria of compounds having only one chiral center, erroneous formulas showing different antipodes on the two sides of the equilibrium are rare. In contrast, with compounds having two or more chiral centers especially with saturated heterocycles, this erroneous representation occurs frequently in the chemical…

  14. Conformal mapping for multiple terminals

    NASA Astrophysics Data System (ADS)

    Wang, Weimin; Ma, Wenying; Wang, Qiang; Ren, Hao

    2016-11-01

    Conformal mapping is an important mathematical tool that can be used to solve various physical and engineering problems in many fields, including electrostatics, fluid mechanics, classical mechanics, and transformation optics. It is an accurate and convenient way to solve problems involving two terminals. However, when faced with problems involving three or more terminals, which are more common in practical applications, existing conformal mapping methods apply assumptions or approximations. A general exact method does not exist for a structure with an arbitrary number of terminals. This study presents a conformal mapping method for multiple terminals. Through an accurate analysis of boundary conditions, additional terminals or boundaries are folded into the inner part of a mapped region. The method is applied to several typical situations, and the calculation process is described for two examples of an electrostatic actuator with three electrodes and of a light beam splitter with three ports. Compared with previously reported results, the solutions for the two examples based on our method are more precise and general. The proposed method is helpful in promoting the application of conformal mapping in analysis of practical problems.

  15. Conformal mapping for multiple terminals.

    PubMed

    Wang, Weimin; Ma, Wenying; Wang, Qiang; Ren, Hao

    2016-11-10

    Conformal mapping is an important mathematical tool that can be used to solve various physical and engineering problems in many fields, including electrostatics, fluid mechanics, classical mechanics, and transformation optics. It is an accurate and convenient way to solve problems involving two terminals. However, when faced with problems involving three or more terminals, which are more common in practical applications, existing conformal mapping methods apply assumptions or approximations. A general exact method does not exist for a structure with an arbitrary number of terminals. This study presents a conformal mapping method for multiple terminals. Through an accurate analysis of boundary conditions, additional terminals or boundaries are folded into the inner part of a mapped region. The method is applied to several typical situations, and the calculation process is described for two examples of an electrostatic actuator with three electrodes and of a light beam splitter with three ports. Compared with previously reported results, the solutions for the two examples based on our method are more precise and general. The proposed method is helpful in promoting the application of conformal mapping in analysis of practical problems.

  16. Conformal mapping for multiple terminals

    PubMed Central

    Wang, Weimin; Ma, Wenying; Wang, Qiang; Ren, Hao

    2016-01-01

    Conformal mapping is an important mathematical tool that can be used to solve various physical and engineering problems in many fields, including electrostatics, fluid mechanics, classical mechanics, and transformation optics. It is an accurate and convenient way to solve problems involving two terminals. However, when faced with problems involving three or more terminals, which are more common in practical applications, existing conformal mapping methods apply assumptions or approximations. A general exact method does not exist for a structure with an arbitrary number of terminals. This study presents a conformal mapping method for multiple terminals. Through an accurate analysis of boundary conditions, additional terminals or boundaries are folded into the inner part of a mapped region. The method is applied to several typical situations, and the calculation process is described for two examples of an electrostatic actuator with three electrodes and of a light beam splitter with three ports. Compared with previously reported results, the solutions for the two examples based on our method are more precise and general. The proposed method is helpful in promoting the application of conformal mapping in analysis of practical problems. PMID:27830746

  17. Temperature: Human Regulating, Ants Conforming

    ERIC Educational Resources Information Center

    Clopton, Joe R.

    2007-01-01

    Biological processes speed up as temperature rises. Procedures for demonstrating this with ants traveling on trails, and data gathered by students on the Argentine ant ("Linepithema humile") are presented. The concepts of temperature regulation and conformity are detailed with a focus on the processes rather than on terms that label the organisms.

  18. Conformational activation of ADAMTS13.

    PubMed

    South, Kieron; Luken, Brenda M; Crawley, James T B; Phillips, Rebecca; Thomas, Mari; Collins, Richard F; Deforche, Louis; Vanhoorelbeke, Karen; Lane, David A

    2014-12-30

    A disintegrin and metalloprotease with thrombospondin motifs 13 (ADAMTS13) is a metalloprotease that regulates von Willebrand factor (VWF) function. ADAMTS13-mediated proteolysis is determined by conformational changes in VWF, but also may depend on its own conformational activation. Kinetic analysis of WT ADAMTS13 revealed ∼ 2.5-fold reduced activity compared with ADAMTS13 lacking its C-terminal tail (MDTCS) or its CUB1-2 domains (WTΔCUB1-2), suggesting that the CUB domains naturally limit ADAMTS13 function. Consistent with this suggestion, WT ADAMTS13 activity was enhanced ∼ 2.5-fold by preincubation with either an anti-CUB mAb (20E9) or VWF D4CK (the natural binding partner for the CUB domains). Furthermore, the isolated CUB1-2 domains not only bound MDTCS, but also inhibited activity by up to 2.5-fold. Interestingly, a gain-of-function (GoF) ADAMTS13 spacer domain variant (R568K/F592Y/R660K/Y661F/Y665F) was ∼ 2.5-fold more active than WT ADAMTS13, but could not be further activated by 20E9 mAb or VWF D4CK and was unable to bind or to be inhibited by the CUB1-2 domains, suggesting that the inhibitory effects of the CUB domains involve an interaction with the spacer domain that is disrupted in GoF ADAMTS13. Electron microscopy demonstrated a "closed" conformation of WT ADAMTS13 and suggested a more "open" conformation for GoF ADAMTS13. The cryptic spacer domain epitope revealed by conformational unfolding also represents the core antigenic target for autoantibodies in thrombotic thrombocytopenic purpura. We propose that ADAMTS13 circulates in a closed conformation, which is maintained by a CUB-spacer domain binding interaction. ADAMTS13 becomes conformationally activated on demand through interaction of its C-terminal CUB domains with VWF, making it susceptible to immune recognition.

  19. Compactification on phase space

    NASA Astrophysics Data System (ADS)

    Lovelady, Benjamin; Wheeler, James

    2016-03-01

    A major challenge for string theory is to understand the dimensional reduction required for comparison with the standard model. We propose reducing the dimension of the compactification by interpreting some of the extra dimensions as the energy-momentum portion of a phase-space. Such models naturally arise as generalized quotients of the conformal group called biconformal spaces. By combining the standard Kaluza-Klein approach with such a conformal gauge theory, we may start from the conformal group of an n-dimensional Euclidean space to form a 2n-dimensional quotient manifold with symplectic structure. A pair of involutions leads naturally to two n-dimensional Lorentzian manifolds. For n = 5, this leaves only two extra dimensions, with a countable family of possible compactifications and an SO(5) Yang-Mills field on the fibers. Starting with n=6 leads to 4-dimensional compactification of the phase space. In the latter case, if the two dimensions each from spacetime and momentum space are compactified onto spheres, then there is an SU(2)xSU(2) (left-right symmetric electroweak) field between phase and configuration space and an SO(6) field on the fibers. Such a theory, with minor additional symmetry breaking, could contain all parts of the standard model.

  20. Evaluating and learning from RNA pseudotorsional space: quantitative validation of a reduced representation for RNA structure.

    PubMed

    Wadley, Leven M; Keating, Kevin S; Duarte, Carlos M; Pyle, Anna Marie

    2007-09-28

    Quantitatively describing RNA structure and conformational elements remains a formidable problem. Seven standard torsion angles and the sugar pucker are necessary to characterize the conformation of an RNA nucleotide completely. Progress has been made toward understanding the discrete nature of RNA structure, but classifying simple and ubiquitous structural elements such as helices and motifs remains a difficult task. One approach for describing RNA structure in a simple, mathematically consistent, and computationally accessible manner involves the invocation of two pseudotorsions, eta (C4'(n-1), P(n), C4'(n), P(n+1)) and theta (P(n), C4'(n), P(n+1), C4'(n+1)), which can be used to describe RNA conformation in much the same way that varphi and psi are used to describe backbone configuration of proteins. Here, we conduct an exploration and statistical evaluation of pseudotorsional space and of the Ramachandran-like eta-theta plot. We show that, through the rigorous quantitative analysis of the eta-theta plot, the pseudotorsional descriptors eta and theta, together with sugar pucker, are sufficient to describe RNA backbone conformation fully in most cases. These descriptors are also shown to contain considerable information about nucleotide base conformation, revealing a previously uncharacterized interplay between backbone and base orientation. A window function analysis is used to discern statistically relevant regions of density in the eta-theta scatter plot and then nucleotides in colocalized clusters in the eta-theta plane are shown to have similar 3-D structures through RMSD analysis of the RNA structural constituents. We find that major clusters in the eta-theta plot are few, underscoring the discrete nature of RNA backbone conformation. Like the Ramachandran plot, the eta-theta plot is a valuable system for conceptualizing biomolecular conformation, it is a useful tool for analyzing RNA tertiary structures, and it is a vital component of new approaches for

  1. Conformity of pediatric/adolescent HIV clinics to the patient-centered medical home care model.

    PubMed

    Yehia, Baligh R; Agwu, Allison L; Schranz, Asher; Korthuis, P Todd; Gaur, Aditya H; Rutstein, Richard; Sharp, Victoria; Spector, Stephen A; Berry, Stephen A; Gebo, Kelly A

    2013-05-01

    The patient-centered medical home (PCMH) has been introduced as a model for providing high-quality, comprehensive, patient-centered care that is both accessible and coordinated, and may provide a framework for optimizing the care of youth living with HIV (YLH). We surveyed six pediatric/adolescent HIV clinics caring for 578 patients (median age 19 years, 51% male, and 82% black) in July 2011 to assess conformity to the PCMH. Clinics completed a 50-item survey covering the six domains of the PCMH: (1) comprehensive care, (2) patient-centered care, (3) coordinated care, (4) accessible services, (5) quality and safety, and (6) health information technology. To determine conformity to the PCMH, a novel point-based scoring system was devised. Points were tabulated across clinics by domain to obtain an aggregate assessment of PCMH conformity. All six clinics responded. Overall, clinics attained a mean 75.8% [95% CI, 63.3-88.3%] on PCMH measures-scoring highest on patient-centered care (94.7%), coordinated care (83.3%), and quality and safety measures (76.7%), and lowest on health information technology (70.0%), accessible services (69.1%), and comprehensive care (61.1%). Clinics moderately conformed to the PCMH model. Areas for improvement include access to care, comprehensive care, and health information technology. Future studies are warranted to determine whether greater clinic PCMH conformity improves clinical outcomes and cost savings for YLH.

  2. Fake conformal symmetry in unimodular gravity

    NASA Astrophysics Data System (ADS)

    Oda, Ichiro

    2016-08-01

    We study Weyl symmetry (local conformal symmetry) in unimodular gravity. It is shown that the Noether currents for both Weyl symmetry and global scale symmetry vanish exactly as in conformally invariant scalar-tensor gravity. We clearly explain why in the class of conformally invariant gravitational theories, the Noether currents vanish by starting with conformally invariant scalar-tensor gravity. Moreover, we comment on both classical and quantum-mechanical equivalences in Einstein's general relativity, conformally invariant scalar-tensor gravity, and the Weyl-transverse gravity. Finally, we discuss the Weyl current in the conformally invariant scalar action and see that it is also vanishing.

  3. Conformal Invariance in Driven Diffusive Systems at High Currents

    NASA Astrophysics Data System (ADS)

    Karevski, D.; Schütz, G. M.

    2017-01-01

    We consider space-time correlations in driven diffusive systems which undergo a fluctuation into a regime with an atypically large current or dynamical activity. For a single conserved mass we show that the spatiotemporal density correlations in one space dimension are fully determined by conformal field theory with central charge c =1 , corresponding to a ballistic universality class with dynamical exponent z =1 . The full phase diagram for general atypical behavior exhibits the conformally invariant regime and, for atypically low current or activity, a region of phase separation. The phase transition line between these two regimes corresponds to typical behavior and the dynamics belongs to the Kardar-Parisi-Zhang universality class with dynamical exponent z =3 /2 , except for a diffusive point with z =2 . The exact universal dynamical structure function is obtained in explicit form from the one-dimensional asymmetric simple exclusion process with periodic and open boundaries in the limit of maximal current.

  4. De novo protein conformational sampling using a probabilistic graphical model

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Debswapna; Cheng, Jianlin

    2015-11-01

    Efficient exploration of protein conformational space remains challenging especially for large proteins when assembling discretized structural fragments extracted from a protein structure data database. We propose a fragment-free probabilistic graphical model, FUSION, for conformational sampling in continuous space and assess its accuracy using ‘blind’ protein targets with a length up to 250 residues from the CASP11 structure prediction exercise. The method reduces sampling bottlenecks, exhibits strong convergence, and demonstrates better performance than the popular fragment assembly method, ROSETTA, on relatively larger proteins with a length of more than 150 residues in our benchmark set. FUSION is freely available through a web server at http://protein.rnet.missouri.edu/FUSION/.

  5. Conformational Preferences of α-Substituted Proline Analogues

    PubMed Central

    Flores-Ortega, Alejandra; Jiménez, Ana I.; Cativiela, Carlos; Nussinov, Ruth; Alemán, Carlos; Casanovas, Jordi

    2009-01-01

    DFT calculations at the B3LYP/6-31+G(d,p) level have been used to investigate how the replacement of the α hydrogen by a more sterically demanding group affects the conformational preferences of proline. Specifically, the N-acetyl-N’-methylamide derivatives of L-proline, L-α-methylproline and L-α-phenylproline have been calculated, with both the cis/trans isomerism of the peptide bonds and the puckering of the pyrrolidine ring being considered. The effects of solvation have been evaluated using a Self Consistent Reaction Field model. As expected, tetrasubstitution at the α carbon destabilizes the conformers with one or more peptide bonds arranged in cis. The lowest energy minimum has been found to be identical for the three compounds investigated, but important differences are observed regarding other energetically accessible backbone conformations. The results obtained provide evidence that the distinct steric requirements of the substituent at Cα may play a significant role in modulating the conformational preferences of proline. PMID:18351745

  6. 14 CFR 25.813 - Emergency exit access.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Emergency exit access. 25.813 Section 25... Emergency exit access. Each required emergency exit must be accessible to the passengers and located where... following must be provided for each Type III or Type IV exit—(1) There must be access from the nearest...

  7. Launch system design for access to space

    NASA Technical Reports Server (NTRS)

    Barnes, Corbin

    1994-01-01

    Here, a hybrid launch system is developed. The hybrid launch system combines the lower operating cost advantage of an non-man-rated SSTO (Single Stage to Orbit) MLV (Medium Launch Vehicle) with the crew survivability advantage of a ballistic escape pod. Ultimately, it was found that a non-man-made MLV is configured the same as a man-rated MLV and offers no significant savings in operational cost. However, addition of the proposed escape system would increase the crew survivability rate of the SSTO while incurring only a small cost per pound payload penalty.

  8. Access to Space: Beyond the Next Generation

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2001-01-01

    This viewgraph presentation provides information on the many considerations involved in the development of next generation launch vehicles. The pros and cons of single stage and two stage vehicles are presented, as are the pros and cons of jet engines (normal, ramjet, and scramjet) and rocket engines. There is a possibility of utilizing a Rocket-based Combined Cycle Engine (RBCC) which functions as both a jet and rocket engine at different points of ascent. Direct impulse launch systems, tether systems, laser-launch systems, launch assist systems, and a geosynchronous skyhook are also discussed.

  9. BCL::Conf: small molecule conformational sampling using a knowledge based rotamer library.

    PubMed

    Kothiwale, Sandeepkumar; Mendenhall, Jeffrey L; Meiler, Jens

    2015-01-01

    The interaction of a small molecule with a protein target depends on its ability to adopt a three-dimensional structure that is complementary. Therefore, complete and rapid prediction of the conformational space a small molecule can sample is critical for both structure- and ligand-based drug discovery algorithms such as small molecule docking or three-dimensional quantitative structure-activity relationships. Here we have derived a database of small molecule fragments frequently sampled in experimental structures within the Cambridge Structure Database and the Protein Data Bank. Likely conformations of these fragments are stored as 'rotamers' in analogy to amino acid side chain rotamer libraries used for rapid sampling of protein conformational space. Explicit fragments take into account correlations between multiple torsion bonds and effect of substituents on torsional profiles. A conformational ensemble for small molecules can then be generated by recombining fragment rotamers with a Monte Carlo search strategy. BCL::Conf was benchmarked against other conformer generator methods including Confgen, Moe, Omega and RDKit in its ability to recover experimentally determined protein bound conformations of small molecules, diversity of conformational ensembles, and sampling rate. BCL::Conf recovers at least one conformation with a root mean square deviation of 2 Å or better to the experimental structure for 99 % of the small molecules in the Vernalis benchmark dataset. The 'rotamer' approach will allow integration of BCL::Conf into respective computational biology programs such as Rosetta.Graphical abstract:Conformation sampling is carried out using explicit fragment conformations derived from crystallographic structure databases. Molecules from the database are decomposed into fragments and most likely conformations/rotamers are used to sample correspondng sub-structure of a molecule of interest.

  10. Meta-conformal invariance and the boundedness of two-point correlation functions

    NASA Astrophysics Data System (ADS)

    Henkel, Malte; Stoimenov, Stoimen

    2016-11-01

    The covariant two-point functions, derived from Ward identities in direct space, can be affected by consistency problems and can become unbounded for large time- or space-separations. This difficulty arises for several extensions of dynamical scaling, for example Schrödinger-invariance, conformal Galilei invariance or meta-conformal invariance, but not for standard ortho-conformal invariance. For meta-conformal invariance in (1+1) dimensions, which acts as a dynamical symmetry of a simple advection equation, these difficulties can be cured by going over to a dual space and an extension of these dynamical symmetries through the construction of a new generator in the Cartan sub-algebra. This provides a canonical interpretation of meta-conformally covariant two-point functions as correlators. Galilei-conformal correlators can be obtained from meta-conformal invariance through a simple contraction. In contrast, by an analogus construction, Schrödinger-covariant two-point functions are causal response functions. All these two-point functions are bounded at large separations, for sufficiently positive values of the scaling exponents.

  11. Conformal Window and Correlation Functions in Lattice Conformal QCD

    NASA Astrophysics Data System (ADS)

    Iwasaki, Y.

    We discuss various aspects of Conformal Field Theories on the Lattice. We mainly investigate the SU(3) gauge theory with Nf degenerate fermions in the fundamental representation, employing the one-plaquette gauge action and the Wilson fermion action. First we make a brief review of our previous works on the phase structure of lattice gauge theories in terms of the gauge coupling constant and the quark mass. We thereby clarify the reason why we conjecture that the conformal window is 7 ≤ Nf ≤ 16. Secondly, we introduce a new concept, "conformal theories with IR cutof" and point out that any numerical simulation on a lattice is bounded by an IR cutoff ∧IR. Then we make predictions that when Nf is within the conformal window, the propagator of a meson G(t) behaves at large t, as G(t) = c exp (-mHt)/tα, that is, a modified Yukawa-type decay form, instead of the usual exponential decay form exp (-mHt), in the small quark mass region. This holds on an any lattice for any coupling constant g, as far as g is between 0 and g*, where g* is the IR fixed point. We verify that numerical results really satisfy the predictions for the Nf = 7 case and the Nf = 16 case. Thirdly, we discuss small number of flavors (Nf = 2 ˜ 6) QCD at finite temperatures. We point out theoretically and verify numerically that the correlation functions at T/Tc > 1 exhibit the characteristics of the conformal function with IR cutoff, an exponential decay with power correction. Investigating our numerical data by a new method which we call the "local-analysis" of propagators, we observe that the Nf = 7 case and the Nf = 2 at T ˜ 2Tc case are similar to each other, while the Nf = 16 case and the Nf = 2 at T = 102 ˜ 105Tc cases are similar to each other. Further, we observe our data are consistent with the picture that the Nf = 7 case and the Nf = 2 at T ˜ 2Tc case are close to the meson unparticle model. On the other hand, the Nf = 16 case and the Nf = 2 at T = 102 ˜ 105Tc cases are close to

  12. Gauge natural formulation of conformal gravity

    SciTech Connect

    Campigotto, M.; Fatibene, L.

    2015-03-15

    We consider conformal gravity as a gauge natural theory. We study its conservation laws and superpotentials. We also consider the Mannheim and Kazanas spherically symmetric vacuum solution and discuss conserved quantities associated to conformal and diffeomorphism symmetries.

  13. Accessibility: Maximum Mobility and Function.

    ERIC Educational Resources Information Center

    Smyser, Michael

    2003-01-01

    Describes how to design school and university labs to comply with Americans with Disabilities Act (ADA) standards, focusing on counter height for students in wheelchairs; appropriate knee space and sink height in sink areas; ADA-compliant fume hoods; accessible laboratory doors and entryways; and safety concerns (e.g., emergency eyewash stations…

  14. 14 CFR 1203a.103 - Access to security areas.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Access to security areas. 1203a.103 Section 1203a.103 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA SECURITY AREAS § 1203a.103 Access to security areas. (a) Only those NASA employees, NASA contractor employees,...

  15. 14 CFR 1203a.103 - Access to security areas.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Access to security areas. 1203a.103 Section 1203a.103 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA SECURITY AREAS § 1203a.103 Access to security areas. (a) Only those NASA employees, NASA contractor employees,...

  16. 14 CFR § 1203a.103 - Access to security areas.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Access to security areas. § 1203a.103 Section § 1203a.103 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA SECURITY AREAS § 1203a.103 Access to security areas. (a) Only those NASA employees, NASA contractor...

  17. 14 CFR 1203a.103 - Access to security areas.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Access to security areas. 1203a.103 Section 1203a.103 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA SECURITY AREAS § 1203a.103 Access to security areas. (a) Only those NASA employees, NASA contractor employees,...

  18. 14 CFR 1203a.103 - Access to security areas.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Access to security areas. 1203a.103 Section 1203a.103 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA SECURITY AREAS § 1203a.103 Access to security areas. (a) Only those NASA employees, NASA contractor employees,...

  19. Generative models of conformational dynamics.

    PubMed

    Langmead, Christopher James

    2014-01-01

    Atomistic simulations of the conformational dynamics of proteins can be performed using either Molecular Dynamics or Monte Carlo procedures. The ensembles of three-dimensional structures produced during simulation can be analyzed in a number of ways to elucidate the thermodynamic and kinetic properties of the system. The goal of this chapter is to review both traditional and emerging methods for learning generative models from atomistic simulation data. Here, the term 'generative' refers to a model of the joint probability distribution over the behaviors of the constituent atoms. In the context of molecular modeling, generative models reveal the correlation structure between the atoms, and may be used to predict how the system will respond to structural perturbations. We begin by discussing traditional methods, which produce multivariate Gaussian models. We then discuss GAMELAN (GRAPHICAL MODELS OF ENERGY LANDSCAPES), which produces generative models of complex, non-Gaussian conformational dynamics (e.g., allostery, binding, folding, etc.) from long timescale simulation data.

  20. Physical studies of conformational plasticity in a recombinant prion protein.

    PubMed

    Zhang, H; Stockel, J; Mehlhorn, I; Groth, D; Baldwin, M A; Prusiner, S B; James, T L; Cohen, F E

    1997-03-25

    PrP(Sc) is known to be the major, if not the only, component of the infectious prion. Limited proteolysis of PrP(Sc) produces an N-terminally truncated polypeptide of about 142 residues, designated PrP 27-30. Recently, a recombinant protein (rPrP) of 142 residues corresponding to the Syrian hamster PrP 27-30 was expressed in Escherichia coli and purified (Mehlhorn et al., 1996). rPrP has been refolded into both alpha-helical and beta-sheet structures as well as various intermediates in aqueous buffers. The beta-sheet state and two pH-dependent alpha-helical states were characterized by CD and NMR. The alpha-helical conformation occurred only after the formation of an intramolecular disulfide bond, whereas the beta-sheet form was accessible either with or without the disulfide. Of the different alpha-helical forms studied, only those refolded in the pH range 5-8 were substantially soluble at physiological pH, exhibiting similar conformations and monomeric analytical sedimentation profiles throughout the above pH range. Furthermore, refolded alpha-rPrP showed NMR chemical shift dispersion typical of proteins with native conformations, although 2D NMR indicated large segments of conformational flexibility. It displayed a cooperative thermal denaturation transition; at elevated temperatures, it converted rapidly and irreversibly to the thermodynamically more stable beta-sheet form. Unfolding of alpha-rPrP by GdnHCl revealed a two-phase transition with a relatively stable folding intermediate at 2 M GdnHCl. The deltaG values were estimated to be 1.9 +/- 0.4 kcal/mol for the first phase and 6.5 +/- 1.2 kcal/mol for the second, consistent with a folding core surrounded by significant segments of flexible conformation. By NMR, alpha-rPrP(acid) isolated at pH 2 without refolding exhibited heterogeneous line widths, consistent with an acid-denatured molten globular state. We conclude that to the extent that rPrP constitutes a relevant folding domain of PrP(C), the various